loading machine in coal mining

conveyor design for mining machines

conveyor design for mining machines

It does not appear likely that this conveyor-system function requirement can be avoided. The emphasis on the continuous miner performance is necessarily such that the conveyor system must be required to handle any material that is provided by the cutting head. Hence, a slowing down in the rate of advance of the miner to produce more finely cut coal and rock cannot be permitted. Similarly, stopping the miner operation to remove oversize material by other means would be unsafe as well as uneconomical.

This functional requirement has a significant influence on the design constraints of the conveyor system. Any potentially applicable concept must have the capability to perform this function if it is to be considered suitable for the continuous miner. However, the loading machine does not present this severe requirement, which means that an optimum system developed for the miner will probably be overdesigned for the loader application. Since there are potential alternatives to the chain conveyor loading machines, such as belt conveyor loaders, the continuous miner presents the more significant problem. The conveyor development discussed in this report is aimed toward this application.

Foster-Miller Associates was awarded a contract by the Bureau of Mines to develop a new conveyor system which can be adapted to existing machinery (continuous miners and loading machines) to reduce the noise from the conveyor to 90 dBA without reducing the performance of the machinery. The work leading to the demonstration of a prototype conveyor system was divided into three phases;

It was originally planned to conduct the Phase I component testing on a simple test stand constructed around standard conveyor components. However, the drastic change in availability of miner and loader parts prevented the required hardware from bring obtained. Fortunately, Peabody Coal Company offered to lend a Joy 14BU10-41CH loader for use during the entire program, including the Phase I component testing. The loader was subsequently brought to the Foster-Miller facilities in Waltham, Massachusetts and was subjected to testing and modification.

The scope of the Phase I study included initial design and component testing to ensure that the system designed would meet the conveyor operating requirements. The recommended design was presented in the Phase I Report, and incorporates the following main features:

This report presents the detailed conveyor system as installed on the loader, including modifications incorporated during the field test program. Furthermore, it discusses the surface and underground testing, presents and discusses the test results, and provides recommendations for further developments.

The new conveyor system was designed and installed on a Joy 14 BU10-41CH loading machine provided by Peabody Coal Company for the test program. The modified loader is shown in Figures 1 to 1. Figure 1 shows the loader operating at the Peabody Spur Mine. Figure 2 is a front view of the machine and shows the rubber belt mounted under and moving with the flight chain. Figure 3 is a side view of the swing conveyor. Figure 4 is a rear view of the machine and shows the conveyor system and transfer point. Figure 5 is a schematic of the machine showing all modifications that affect the noise level of the conveying system.

Following conveyor fabrication and installation on the Joy loader at FMA, the machine was shipped to M.A.T. Industries, West Frankfort, Illinois, for installation of a canopy, system debugging, and surface testing as requested by U.S. Bureau of Mines prior to underground testing in the Spur Mine, Boonville, Indiana. Repairs and modifications to the conveyor design resulted from these preliminary tests which involved operation of the loader in a surface coal pile at the M.A.T. facilities.

After approximately 20 hours of surface testing, the loader was taken underground at the Spur Mine for testing in an operating section. The underground testing was only partly successful. The Joy loader was too large to maneuver easily in the 16 foot wide by 50 to 53 inch high entries. The canopy restricted visibility of the gathering arms. Left side entries became inaccessible as a result of pinching of the coal seam. There was excessive coal spillage at the transfer point preventing shuttle cars from tramming up to the loader. This latter problem was eventually traced to slippage of the tail- conveyor-belt drive pulley on its shaft which reduced the belt speed, and caused the belt conveyor to be incapable of taking sufficient coal away from the transfer point. For these reasons the underground testing was curtailed.

(a) Noise levels measured at the operators ear were between 92 dBA and 99 dBA during surface tests and between 91 dBA and 102 dBA during underground tests depending on type of operation. Measurements of the loader running empty tended toward the higher noise levels. These measurements, after modifications, compare with empty running noise levels of 108 to 110 dBA at the operators position measured before loader modifications. (b) The rubber belt under the chain and flights on the main conveyor of the loader performed satisfactorily during the testing period. Some belt damage sustained during surface testing was caused by excessive chain tension. Proper tension eliminated this damage. However, mine personnel were not convinced that the belt would hold up under prolonged service. The moving rubber belt contributed 1-2 dBA of quieting. (c) The rubber-covered return guide idler, the rubber mounting pads for pillow blocks, and the rubber cover on the flight chain return bed contributed the remainder of quieting achieved, which was the greatest part. (d) Although system coal loading capability underground was not demonstrated equal to the capability of the unmodified loader, the deficiency is attributable to belt drive roll slippage, which was an equipment malfunction rather than a design limitation resulting from the modifications to the design. In addition, the loader was operated within a lower coal seam than that suited for the particular loader used. Quantitative measurement of loading rates was not performed. (e) Unexpectedly high noise from a hydraulic motor and pump were experienced. The apparent cause of this excess noise was an inadequate fluid reservoir.

(a) For application to loading machines, the flight chain may be eliminated and the main conveyor belt driven by the foot or tail pulley. Significant additional noise reduction is possible with this approach if attention is paid to noise generation by the gathering arms, motors, and hydraulic pumps. The height of the transfer section from the front to the mining conveyor may be significantly reduced in this way, making the loader potentially applicable to low coal machines. (b) For continuous miners, where the flight chain must be retained, significant quieting may be obtained by relatively simple modifications including the addition of a rubber-covered return guide idler, rubber mounting pads for pillow blocks, and a rubber cover on the flight chain return bed. These changes are possible without changing the overall height of a miner. (c) Future investigations into reduction of chain pitch are recommended. A major source of noise energy is the chordal action of the chain as it passes over a sprocket. Because the chain forms a polygon around the sprocket rather than a circle, there are fluctuations in effective sprocket radius resulting in chain speed and tension fluctuations and a tendency for the chain to slap surfaces adjacent to its path. Reduction of chain pitch permits more links to wrap on a given size sprocket, thereby reducing chordal action.

The conveyor main frame consists of a reworked Joy 14 BU10-41CH loader provided by Peabody Coal Company for use during the test program. This machine has a 38-inch wide conveyor belt and a 2 inch pitch x 3 inch flight chain.

(a) The swing conveyor portion of the loader was removed, and a new tail pulley combination was added (Figure 6). (b) The major structural modification to the loader is a cantilever bracket welded to the main frame. This bracket is the main support for the swing conveyor, as shown in Drawing No. 20133. (c) A rubber conveyor belt was mounted between the flight chain and the main frame conveyor bed. The flight chain rides on the belt while on the top bed plate of the conveyor. As the flight chain turns around at the tail roller (Figure 6), the conveyor belt rides on the flights through the main frame return bed to within 2 inches of the chain drive sprocket. There, an idler pulley, inserted in the conveyor bed, turns the belt back onto the conveyor bedplate as the flight chain is pulled around the drive sprocket and back on top of the rubber belting, as shown in Figure 7. To eliminate material buildup between the bed plate and the conveyor belt, holes were drilled in the top bed plate along the length of the main frame conveyor.

(d) In conventional conveyor configurations, the flight chain passes around the tail roller and onto the return bed, striking the leading edge of the bedplate as it returns toward the drive sprocket, in the foot section. To eliminate this impact, the new configuration includes an energy-absorbing pulley which is mounted in front of the return bed, as shown in Figure 8. This causes the flight chain to be carried upward past the leading edge of the return bedplate and onto the rubber cover which is bolted to the leading edges of the bedplates of the main frame and the foot section.

The Swing Conveyor consists of a roller bed, drive idler, pulleys, a rubber belt, a 24 HP hydraulic drive motor, a turntable bearing, and a double-acting swing cylinder. See Drawing No. 20133 and Figure 5.

(a) The 25 HP hydraulic motor drives a pulley at the tail end of the Swing Conveyor. (b) The conveyor belt rides on a roller bed in order to reduce belt drag, as shown in Figure 9. (c) The conveyor belt is protected underneath from shuttle car abuse by means of a deflector plate running from the drive roller to within 18 inches of the cantilever bracket (Figure 10). The portion of the conveyor which lies under the main conveyor tail pulley, the point at which the coal is dumped by the flight chain onto the swing conveyor, is fitted with a deflector plate to protect the conveyor rollers from loading impact (Figure 6). The deflector plate also allows easier swing conveyor start-ups (less torque requirement) when coal still remains on the unit. (d) The double-acting cylinder is used to pivot the swing conveyor to the right and left, as shown in Figures 11 and 12. The swing conveyor is mounted on the turntable bearing which, in

turn, is mounted on the cantilever bracket. The maximum angle of conveyor swing is 40 degrees, as compared to 45 degrees for the original loader. (e) The swing conveyor, being mounted on the cantilever bracket, is an integral part of the main frame. Hence, it is raised and lowered in the same manner as a conventional conveyor system.

The Joy loader hydraulic power supply consists of a 10 HP electric motor, a gear pump, and a 24 gallon reservoir. This system is used to raise the foot section and main frame (tail section) hydraulic jacks. It also supplies power to the swing cylinder, which moves the tail section right or left. The pressure requirements of the conventional system are less than 1000 psi.

The swing conveyor belt drive hydraulic motor requires 3000 psi pressure so the 10 HP electric motor and pump were replaced by a 40 HP electric motor and a 3000 psi dual hydraulic pump, as shown schematically in Figure 13. One pump supplies the belt drive motor at 3000 psi pressure, and the other supplies the cylinders described above.

The fabrication and installation of the new conveyor design on the Joy loader were performed at the Foster-Miller Associates facilities in Waltham, Massachusetts, and by local subcontractors. The loader was then shipped to M.A.T. Industries in West Frankfort, Illinois, for installation of a canopy and methane monitor, and preliminary performance testing prior to the underground test program in the Peahody Spur Mine. However, at the recommendation of the Bureau of Mines and Peabody Coal Company, this was extended into a rather comprehensive surface testing program, in which the loader operated in a surface coal pile. The surface and underground test programs are both described in the following sections.

The surface testing program was conducted in a coal pile outside the M.A.T. Industries facilities, as shown in Figure 15. The total operating time of the conveyor system at this site, including the initial conveyor and loader debugging, was approximately 20 hours.

The machine debugging became a considerably greater undertaking than was originally projected. This was partly due to the condition of the loader. Four hydraulic cylinders, were replaced. The drive motor for the hydraulic system was rewired. The loader tracks, and miscellaneous other components were repaired.

A separate, major problem was the inadequate power of the tail conveyor hydraulic motor to drive the tail conveyor belt under conditions of maximum loading. Figure-16 illustrates the amount of coal on the conveyor system that lead to this failure. This problem was solved by increasing the pressure in the hydraulic line driving the motor, and mounting a series of small diameter rollers underneath the conveyor belt to reduce friction between the belt and the bedplate

An apparently minor, but persistent problem, was the buildup of coal on top of the main conveyor bed plate, between the bed plate and the conveyor belt. At the beginning of the surface testing program, this buildup was sufficient to cause excessive tension in the conveyor chain, which in turn stalled the conveyor. Two methods for eliminating this problem were tried. First, a snowplow scraper was installed on top of the belt, within the return bed, and immediately following the rubber covered return idler. Next, an array of holes was drilled in the bod plate along the length of the main frame conveyor. The snowplow scraper was not effective, but the holes in the bed plate reduced the buildup significantly, by providing scraping edges against the belt and permitting any captured coal dust to pass through.

The underground test program was conducted in the Peabody Spur Mine, near Boonville, Indiana. This is a new mine which enters the coal seam at the base of a 60-foot high wall of the old Squaw Creek strip mine. The coal seam is the Illinois No. 5 seam, and ranges in thickness from approximately 50 inches to more than 65 inches.

Seven main entries have been driven past an area where six submains have been turned and are now being driven. The entries are generally 20 feet wide on 50 foot centers, both inby-outby and left to right. However, during the time the underground test program was conducted, bad roof conditions had been encountered, requiring a limitation on entry width to 16 feet. Furthermore, the coal seam had pinched down to approximately 50-53 inches in the working section.

The limited entry height and width resulted in rather adverse operating conditions for the modified Joy 14 BU10-41CH loader, which is approximately 11 feet wide, 28 feet long, and 45 inches high. The top of the canopy was lowered to 48 inches to avoid jamming it against the roof, and consequently, the loader operator was unable to see the gathering arms and the conveyor foot section. This lack of operator visibility presented problems in clean-up work and in loading the shuttle cars.

Following approximately 23 hours of loader operation in the mine, the coal seam at the left side of the working section pinched down even more, preventing the loader from moving up to that working face. The decision was then made, in consultation with the Bureau of Mines, to terminate the underground testing program and the loader was taken outside.

Following the modification of the tail conveyor during the surface testing program, the conveyor system performed very well, and was able to discharge coal satisfactorily even at the highest rates of loading attempted in the surface coal piles.

Towards the end of the underground testing program, during the visit by the Bureau of Mines representative, a problem with spillage became apparent at the transfer point from the main conveyor to the tail conveyor, caused by the inability of the tail conveyor to move as much coal as the main conveyor.

The rubber belt under the conveyor chain on the main conveyor had been the subject of some concern. This belt, which is not independently powered, but is driven by the friction between it and the conveyor chain, typically travels at approximately one half the speed of the flight chain. On examining the belt following the surface testing at M.A.T. Industries, it was found that no significant wear had been caused by coal and rocks, but some damage had occurred to the strip of belt riding under the conveyor chain. This was probably caused at the tail roller, where the chain moves relative to the belt while turning around a small radius.

To minimize the damage to the new belt installed for the underground testing, the flight chain takeup tension was reduced. The flight chain may have been excessively tensioned during the surface testing. Final examination of the belt indicated that this was successful, as shown in Figure 17. The belt is scuffed and scraped from contact with the flights, coal, and the conveyor chain but the damage is contained within 1/32 inches of the surface, and in no place has the fabric ply been damaged by shearing or impact.

We believe, however, that belt wear would be even further reduced if the belt traveled at the same speed as the flight chain. Hence, we recommend that a belt drive be incorporated into future versions of this system.

An additional modification that should be considered would consist of replacing the steel tail roller on the main conveyor with a roller covered by an approximately one-inch layer of hard rubber (70-80 durometer). This would reduce possible belt damage by the flight chain.

The return idler and the rubber belt placed over the main conveyor return bed also performed satisfactorily. Some belt damage at the leading edge of the return bed occurred during the surface testing, when the return idler was mounted sufficiently low that the conveyor chain hit against this edge. This problem was eliminated by raising the return idler approximately inch.

The holes drilled in the top bed plate to eliminate coal buildup under the conveyor belt were quite effective in reducing this problem to a manageable level. However, it is believed that the coal buildup can be further reduced by installing the snowplow scraper immediately adjacent to the foot section idler pulley rather than back by the rubber-covered return idler. By this means, the conveyor belt would be scraped clean of coal dust just before it turns around the idler pulley and onto the top of the bed plate.

The swing conveyor belt showed a tendency to ride over to one side while turned and loading, particularly when the conveyor was raised, causing the conveyor belt to ride on a transverse slope. This problem was minimized by maintaining proper belt adjustment and belt tension which, however, did not fully eliminate occasional scraping of the belt against the side of the conveyor. No measurable belt damage was apparent or is expected by this failure to track properly, but the problem can probably be alleviated by installing tracking idlers along the sides of the conveyor belt.

The noise levels at several positions around the loader were measured during the surface and underground test programs. Measurements were made at the operators ear, at approximately one foot from the side of the loader by the gathering arms, at the transfer point from the main to the stub conveyor, and at the end of the stub conveyor. Measurements were made with the conveyors running empty and fully loaded with coal. Table I presents a summary of the noise levels obtained during the test programs. Under the most advantageous operating conditions, the noise levels at the operators ear were approximately 93 dBA and 95 dBA, respectively, on the surface and during underground testing.

noise levels (when running empty) which varied from 93 to 98 dBA. The cause of this variation was eventually diagnosed as an inadequate hydraulic fluid supply tank. With the conveyor frame or the foot section in a raised position, the extended hydraulic lift cylinders drained the supply tank to the extent that hydraulic fluid passing through the pump contained an excessive amount of air. This caused an uneven loading on the hydraulic pump vanes and dynamic imbalance of the pump and motor shafts, resulting in higher noise levels. During the final surface testing, a lead foam blanket was wrapped around the motor and pump, as shown in Figure 18. The corresponding noise level readings at the operators ear were 89/90 dBA due to the hydraulic pump only, 92/93 dBA with the conveyor running empty, and 93 dBA with the conveyor loading. The increased noise level while loading was presumably caused by coal scraping against the conveyor side plates, and by coal discharging from the main to the stub conveyor at the transfer point and from the end of the stub conveyor.

Table IIA shows that significant quieting of the loader, by about 15 dBA, was achieved by the modifications made. Table IIB is shown to illustrate the wide variations in noise measurements resulting from both changes in operating condition and changes in sensor location. The conventional Joy 14 BU10 (low machine) is a smaller loader and inherently less noisy than the 14 BU10-41CH modified under this contract, but the data indicate a similarly broad range of noise measurements with similar correlation to operating condition and sensor location.

The objective of this program was to develop a new conveyor system that could be adapted to existing continuous miners and loading machines and would exhibit a noise level of 90 dBA from the conveyor without reducing the performance of the machinery.

(a) The measured noise levels at the operators ear were 92/93 dBA at the surface and 95/96 dBA underground. The modification to the particular loader of this program reduced noise levels by approximately 15 dBA. (b) During surface testing, the conveyor system performed without apparent reduction in loading capacity. Capacity reductions observed in underground tests are attributable to mechanical failure (belt drive pulley slippage on its shaft) and to mine dimensions not well suited to the design of the particular machine used. The conveyor design modifications developed in this program can be applied to moderate or high coal. The vertical dimension of the transfer point presents a limit to applications in low coal. (c) The durability of a rubber belt under chains and flights was not adequately tested because of the short duration of operating tests. Some belt damage was caused by the chain during the surface tests due to excessive chain tension. With lower chain tension, underground tests showed no additional wear. (d) The rubber-covered return guide idler, the rubber cover on the flight chain return bed, and the rubber mounting pads for the sprocket and roller pillow blocks were successful in terms of reduced noise levels and showed no wear in the limited testing time available. These features are worthy of note because, besides providing effective quieting, they may be incorporated into a conventional swing conveyor machine with only minor alteration. The quieting achieved by the main belt, although measurable, was significantly less.

(a) The design criteria for loaders and continuous miners are sufficiently diverse that future attempts at quieting conveyors should consider these applications individually. (b) A conveyor system for loading machines might eliminate the flight chain from the front conveyor, using belts only. The major noise contributor then would be the gathering arms which could be the target of another effort. By eliminating chains and flights, the height of the transfer point may be reduced by about 6 inches, thus making a machine suited for lower coal seams. There are indications from this program that a belt can adequately resist wear in this application. (c) A conveyor system for continuous miners, which requires the use of chains and flights, may best be quieted by incorporating the rubber-covered return guide idler, the rubber cover on the flight chain return bed, and the rubber mounting pads for the sprocket end roller blocks. The incorporation of a moving belt under the chain and flights is not recommended. The quieting achieved by this method, though measurable, is not justified by the complexity of the modification. (d) Future effort to mechanically quiet conveyors should emphasize redesign of chains and flights to permit the shortest possible chain pitch to be used. The shorter the pitch the greater will be the number of sprocket teeth at a given pitch diameter. The fluctuations in chain pitch line velocity (chordal effect) are inversely proportional to the number of sprocket teeth. These velocity fluctuations are the major source of vibration input at a sprocket and resultant chain slap.

The approximate cost for a conveyor modification as tested would be, including materials and direct labor costs, approximately $18,000. Following is a breakdown of these costs based on the test unit fabricated for this program. This compares with a cost of approximately $500 to provide rubber pads for pillow blocks, a rubber-covered steel shaft and mounting at the return end of the main conveyor and belting applied to the return bed plate. Drawings 11484 and 20733, Sheets 1 and 2, illustrate the configuration built and tested.

Noise measurement studies conducted in underground coal mines have shown that several mine occupations expose individuals to noise levels that result in shift noise exposures in excess of the safe standards established by the Walsh Healey criteria. In particular, operators of continuous miners and loading machines are subjected, during loading, to noise levels ranging from 89 to 108 dBA. The principal sources of noise on these machines are in the chain conveyor system. Efforts to date to eliminate or reduce the conveyor noise have been conducted along modifications of the existing mechanical system. An alternate approach is to use a new conveyor design to reduce noise levels without reducing the performance of the machine.

Foster-Miller Associates has been awarded a contract by the Bureau of Mines to develop a new conveyor system which can be adapted to existing machinery (continuous miners and loading machines) to reduce the noise from the conveyor to 90 dBA without reducing the performance of the machinery. The work leading to the demonstration of a prototype conveyor system has been divided into three phases;

The basic objective of this program is to develop a new conveyor system which can be adapted to continuous miners and loaders to reduce the noise from the conveyor to 90 dBA without reducing the performance of the machinery.

The scope of the Phase I study included initial design and component testing to ensure that the system designed meets ail the operating requirements. This report presents the results of the component testing and the conveyor design, significant aspects of which arc listed below:

The purpose of the conveyor system on a continuous miner or loading machine is to transport the coal from the base region to the material handling system behind the machine. In the case of a loading machine the capability of the conveyor system to transport the design load is a necessary and sufficient design consideration, i. e., any conveyor concept which can satisfy the transport requirement is a potential candidate for the conveyor system.

For the continuous miner, however, there are additional performance requirements that must be taken into consideration. Since the currently used chain conveyor system is such a sturdy device, which can suffer a great deal of abuse and still remain operational, the practice has developed to use the conveyor as a rock and coal breaker as well as a transport system. For example, if the cutting head breaks off a large piece of rock or coal from the mining face, the gathering arms will push it onto the conveyor chute, and the flights will move it along the chute until, if it exceeds the critical size, it will become wedged between the chute and the cutting head boom. According to current miner operation practice, the flights will continue to move, breaking off and grinding down the material until it has been reduced sufficiently in size to pass through the restriction. If the material is wedged in sufficiently well to stall the chain drive, the conveyor is engaged in reverse long enough to free the flights, after which another attempt is made to crush the rock.

It does not appear likely that this conveyor system functional requirement can be avoided. The emphasis on the continuous miner performance is necessarily such that the conveyor system must be required to handle any material that is provided by the cutting head. Hence, a slowing down in the rate of advance of the miner to produce more finely cut coal and rock cannot be permitted. Similarly, stopping the miner operation to remove oversize material by other means would be unsafe as well as uneconomical.

This functional requirement has a significant influence on the design constraints of the conveyor system. Any potentially applicable concept must have the capability to perform this function if it is to be considered suitable for the continuous miner. However, the loading machine does not present this severe requirement, which means that an optimum system developed for the miner will probably be overdesigned for the loader application. Since there are alternatives to the chain conveyor loading machines, we believe that the continuous miner presents the more significant problem and have aimed our concept development toward this application.

(a) Dual Semi-Elastic Belt Concept. This concept was presented in the Technical Proposal, and considers two semi-elastic belts, capable of 45 degree horizontal turns, running between the conveyor bed plate and the chains and flights.

Although similar types of belts are currently being used in face haulage conveyor systems, we concluded that the technical risk of this approach, particularly with respect to belt durability, was too high to warrant further consideration.

(b) Dual Belt Support Concept. This concept, also presented in the Technical Proposal, differs from the previous one mainly in that the belts do not permit horizontal turns. Instead, a separate belt conveyor mounted aft of the fixed belt/chain conveyor provides the 45 degree turning capability.

This concept was considered and tested quite thoroughly during the program, but as it permitted the conveyor chain to impact on the bed plate between the two belts, it did not achieve the noise reduction objectives.

(c) Single Full-Width Belt Concept. This concept is very similar to that presented above, except that a single, full-width belt runs between the chains and flights and the bed plate. At the foot end, the belt runs on an idler roller mounted immediately behind the drive sprocket roller on which the chain and flights run. At the tail end, the belt and chain/flights turn around a common idler roller.

This concept has been shown to be quite successful. It achieved the noise reduction objectives and appears promising in terms of durability and resistance to operational abuse. A more detailed description of this concept follows in Section 4.

We had originally planned to conduct the Phase I component testing on a simple test stand constructed around standard conveyor components. However, the recent drastic change in availability of miner and loader parts prevented us from obtaining the required hardware. Fortunately, Peabody Coal Company offered to lend us a Joy 14BU10-41CH loader for use during the entire program, including the Phase I component testing. The loader was subsequently brought to the Foster-Miller facilities in Waltham, Massachusetts and has been subjected to testing and modification.

The Joy loader is stationed outdoors adjacent to the Foster-Miller workshop, as shown schematically in Figure 1. During baseline and subsequent acoustic tests, measurements have been taken at the following positions, as indicated in Figure 1.

Due to the proximity of the loader to the wall, the measured acoustic data will not correspond to hemispherical face field measurements. In particular, the measured values at the operators position will be from 3 to 6 decibels higher than the corresponding free field values. The three dB uncertainty arises because of the distributed noise source with varying spectrum characteristics.

The conversion from free field values to the mine environment also embodies some uncertainty, as it depends on the mine passage reverberation characteristics. Generally, however, we consider that the direct field and the reverberant field are of equal intensity at a distance of 5 to 10 ft from a machine placed in a mine entry. Hence, a conservative estimate is obtained by assuming that the noise level at the operators position is 3 dB higher than the corresponding free field value.

Table- I presents a summary of the noise levels measured during the program, at the measurement positions identified in Figure 1. The baseline measurements served to identify the dominant sources of noise. A series of modifications were implemented on this configuration to determine the noise reduction potential, as identified in Table I. It is apparent that the rubber belt approach gave promising results.

On this basis a new conveyor configuration was fabricated, consisting of a non-turning, shortened chain conveyor with rubber belts between the chain/flights and the bed plate. This configuration initially incorporated twin rubber belts and a spring-loaded tail shaft, but acoustic measurements showed that noise generation due to the belt slapping on the bed plate was excessive. This problem was removed by going to a single, full-width rubber belt which turned around a separate idler roller mounted immediately behind the foot sprocket roller. A substantial noise reduction resulted. Finally, the excessive noise generation by the chain/flights slapping against the return bed plate was eliminated by running the flights on guide strips mounted on a rubber belt within the return bed duct. Significant additional noise reduction resulted.

The final recommended configuration has a measured noise level at the operators position of 93.5 dBA. This corresponds to a free field noise level of 87.5 to 90.5 dBA, and a noise level in the mine environment, at the operators position, of 90.5 to 93.5 dBA.

Our final recommended design, the development and component testing of which has been discussed in the preceding sections, is shown schematically in Figure 2. Detailed design information is given in three separate drawings which are attached to this report;

The main conveyor incorporates a full width rubber belt which runs, between the chain/flights and the conveyor bed plate. In addition, it includes a separate idler roller for the belt, mounted immediately behind the foot sprocket roller, a fixed tail shaft takeup arrangement, an idler roller guiding the chain/flights into the return bed, and guide strips /isolators mounted in the return bed.

We have considered the question of belt durability in the mine environment. Prolonged running of the conveyor during the component testing produced no signs of wear. Furthermore, we have recently been made aware that Joy Manufacturing Co. used to build a loader for use in hard rock mining that incorporated a straight rubber belt conveyor.

The tail conveyor is a simple rubber belt conveyor design, driven by a hydraulic motor. The conveyor is mounted on a turntable bearing that is attached to the main conveyor frame by a cantilever bracket. We have paid particular attention to specifying standard, off-the-shelf components in the conveyor design in order to avoid delivery problems during the fabrication phase.

coal mining - an overview | sciencedirect topics

coal mining - an overview | sciencedirect topics

Coal mining traditionally took place underground, with men and equipment following seams of coal deep within mountains. Since the 1960s, surface mining methods have become more common, and today they account for more than half of the coal produced in the United States. In this approach, also known as strip mining, oversized bulldozers remove the land surface until coal is exposed, producing large amounts of waste rockand dustin the process.

Historically, destruction of forests often accompanied underground coal mining in the United States. The usual practice in the 1800s was to cut down all trees with commercial value on the overlying land before beginning to mine. Much of the timber was used for props in the coal mine shafts and for railroad ties as track was laid to carry away the coal.

Both underground mining and surface mining of coal cause acid mine drainage. This problem occurs when the mineral iron disulfide is exposed to water and air, leading to the formation of sulfuric acid. Large volumes of acidic liquid drain into local streams, killing fish as well as aquatic plants.

An extreme form of strip mining now being practiced in the Appalachian region of the United States is known as mountaintop removal. As the name suggests, several hundred feet are sheared off the tops of mountains that are close to one another, exposing the coal, which is removed. The waste rock is dumped into valleys so that a set of neighboring mountains in effect become a single plateau. The resulting valley fill buries streams and may become unstable as it becomes saturated with water; its impacts on local groundwater transport are unknown.

Coal mining is usually subject to a royalty and the national corporation tax on income, net of allowable costs. The former is sometimes in the form of an excise tax of a fixed value per ton mined. Other cases are in the form of a revenue tax, which relates the tax payable to the value of sales (often approximately 10%). Both can have strong disincentive effects if the rates are set too high because, with falls in the price of coal or increases in the costs of production, the return to the producing firm can even become negative. Countries with federal systems, such as Canada, impose federal and provincial company income taxes as well as provincial royalty payments.

Coal production in some countries, notably within the European Union, has been subsidized by a number of fiscal devices in order to protect employment. This reduces the effective tax rate and the net money collected from the sector.

In the light of the world's focus on climate change and greenhouse gas emissions, any country building a new coal-fired power station faces condemnation and hostility from environmentalists. Investors and banks no longer finance coal-fired power plants. Historical US coal mining giants such as Peabody and Arch Coal have fallen to bankruptcy in the past decade. As just one example, US coal production fell by nearly 40% in just 1year as of April 2016.

The single largest coal miner globally is Coal India, a state-owned organization with some 80+ mining areas, which mined over half-a-billion tonnes in 2016. Driven by India's political desire to achieve improved energy security for its burgeoning population, Coal India is seeking to acquire foreign assets, with coking coal sources in Australia and other South African targets for its acquisition policies.

BHP Billiton can trace its ancestry back to Indonesia in the 19th Century. Billiton was a tin miner, but when merged with BHPa minerals mining company from Australiait has become one of the global conglomerates. As well as coal, BHP has interests in copper and iron ore, as well as petroleum. More recently, cost reductions, and greater productivity initiatives have resulted in all its operations becoming positive cash generators, thus anticipating improved future market conditions.

By contrast, a much more modern creation, China's Shenhua Group, is a directly state-owned and controlled Chinese company that was started in 1995. It is the most prestigious coal miner in China, with high levels of modernity and the greatest global distribution reach. A recent merger of Shenhua with power-generator Guodian Corporation has created a $271 billion behemoth to become the world's second-largest company by revenue.

After a debilitating filing for bankruptcy protection, the US-based Arch Coal has become one of America's leading coal producers, selling 96 million tonnes of coal in 2016. Active coal mining operations in Wyoming, West Virginia, Colorado, and Illinois represent a 13% share of America's coal demand.

Anglo American plc can trace their roots back over a 100years to the gold and diamond fields of South Africa. Anglo American has evolved into a large diversified miner, with a geographically diverse coal mining portfolio of assets. They are the world's third-largest supplier of metallurgical coal and are diversifying by selling off non-core assets to sharpen its focus to meet the future challenges facing all the companies involved in coal mining with the transition to a low-carbon world.

Coal mining was one of the last major industries in America to mechanize production. From the beginning of the 19th century through the first two decades of the 20th century, the manner in which coal was extracted from underground mines and brought to the surface changed very little. Before the advent of the mechanical loading machine in the 1920s, miners typically broke coal from the mine face using picks and wedges and shoveled it by hand into coal cars. Loaded cars were then pushed to the surface by miners or pulled by horses or other animals. By the end of the 19th century, miners were undercutting the seam and using drills and explosives to increase productivity. Considering that a miner's pay was directly linked to the amount of coal he mined and the number of cars he filled, new methods of mining that saved labor and increased productivity were quickly adopted.

As demand for coal increased over time, companies sought to overcome bottlenecks in the production process. When overexpansion and competition began to cut into profits, and unionization forced the cost of coal production to go up, the drive to mechanize underground mining gained momentum. The logical starting point was to replace the hand-loading system with one that emphasized the use of mechanical loading machines. From the 1930s to the 1970s, the introduction of mechanical loaders, cutting machines, continuous miners, and longwall mining changed forever the way coal would be mined.

Another aspect of mining transformed by mechanization was in the area of haulage. During the pick and hand-loading era, miners shoveled coal into wagons and pushed them to the surface. Drift mines were generally constructed so that they pierced the hillside at a slight upward angle to allow for drainage and to facilitate the transport of loaded cars to the tipple. As mines grew in size and the distance to the tipple increased, companies turned to animal power as the principal means of haulage. When larger coal cars came on the scene, mechanical and electrical haulage, including conveyors, became increasingly necessary.

From the vantage point of the coal operator, mechanization offered several advantages. It allowed for more easily loaded coal, reduced the need for explosives, and lowered timbering costs. Most important, mechanization permitted greater amounts of coal to be mined. Mechanization had its drawbacks, however, at least from the perspective of the miner, for the introduction of laborsaving equipment greatly reduced the need for a large workforce. The introduction of the mechanical coal-loading machine, for instance, reduced the need for coal miners by approximately 30% industrywide between 1930 and 1950. According to Ronald Lewis, black miners bore the brunt of layoffs during this period because they were disproportionately employed as hand loaders. The continuous miner, which combined cutting, drilling, blasting, and loading functions in one machine, had a similar impact. After the introduction of the continuous miner, the number of miners working in West Virginia was cut by more than half between 1950 and 1960. The impact of mechanization also shows up clearly in production and employment figures for Ohio. Between 1950 and 1970, coal production in this state climbed steadily despite a 90% decrease in the number of underground mines and an 83% decline in the size of the labor force. Starting in the 1970s, longwall mining cut even further into employee rolls.

Mechanization presented miners with other problems as well. In mining's early days, miners walked to and from the mine face and relied on natural ventilation to prevent the buildup of mine gas. As mines expanded in size, miners had to walk greater distances to get to work, and problems with ventilation and illumination arose. To facilitate the movement of men, electric trolleys were introduced to the mines. Dust and gas problems were alleviated somewhat by the installation of mechanical fans. Meanwhile, illumination was improved when safety lamps and electric lights were substituted for candles. While solving some problems, these and other solutions contributed to others. In the words of one authority on the matter, now workers could be crushed, run over, squeezed between cars, or electrocuted on contact with bare trolley wires. In addition, some of the new machinery generated sparks and produced tremendous amounts of ignitable coal dust.

Underground coal mining, as in any producing enterprise, requires an infusion of industrial engineering to maximize safety and productivity. Coal mine design practice has shown that safety and productivity are mutually inclusive goals.

Underground mining methods are a mix of continuous and batch processes. For example, while the continuous miner is extracting the coal from the face of the entry, the process is in continuous mode. The continuous miner has to stop mining frequently to allow loaded shuttle cars to switch out with empty shuttle cars, to advance the face ventilation system, and to allow roof bolts to be installed. These stoppages cause the face operations to be an overall batch process. Once the shuttle cars dump the coal onto a conveyor belt, the material is continuously transported outside to a stockpile. The coal is then fed through a processing facility that crushes the coal and removes impurities to customer specifications in continuous processing. Underground coal mine design is optimized when the batch processes that occur in underground mining are engineered to become continuous processes. An example of an effort in this area has been the introduction of continuous haulage equipment, which in certain conditions replace the shuttle car: a batch process.

Mine surveying plays a key role in both surface and underground coal mining. Surveying is used to direct the mining advancement as planned, to monitor performance giving feedback on issues of underground extraction ratio and surface pit recovery, to define overburden rehandle, and to perform checks against weighed coal production for inventory control.

The coal mining organization we visited is an Australian publicly listed organization. While our discussions with managers were based on Australian operations, this company has an offshore majority shareholder and is in the global top 10 pure-play coal companies (based on reserves) in the world. The company operates mines both independently and as joint ventures. In the Australian operations, the coal is mined using either open cut or underground methods. The underground methods comprise either bord and pillar operations, or more commonly the longwall mining method. Each method requires extensive government approvals with detailed background reports on the proposed infrastructure developments. The coal price is market driven and revenue estimations are also aligned with government mining approvals. The company also participates in some upstream and downstream components of the value chain of the mining industry, such as railway and port developments. Their profitability is determined by pricing, cost management initiatives (such as lean manufacturing initiatives), global supply and demand for coal, the quality of the coal, foreign exchange fluctuations as well as the maturity of their mines and prospect of new mine developments. The latter is sometimes difficult to achieve and stranded assets arise where land purchased (for mining purposes with approvals) has subsequently been rezoned and permits reneged by governments.

We visited the head office on several occasions, having arranged individual meetings and joint discussions with three key managers: The CFO, Strategic Asset Manager, and the Public Relations Manager, who also managed the sustainability strategy for the organization. The head office was relatively small and functional, as the key activity was at the coalface, literally, with several coalmines situated throughout Australia. The following discussion is based on our written notes (rather than recorded interviews, as above). These were largely, informal meetings based on an earlier introduction from one of the Directors.

The first meeting was with the CFO, who explained the accounting function as relatively traditional, with accountants in the field largely involved in the market-based accounting numbers, derived for financial reporting. Any calculations that would be required for investment appraisal would be initial estimates of numbers that would need to be included as initial outlays, terminal values, and cash flows. Thus any biodiversity impacts that were recognized would eventually come to the accountant to be formalized as a financial number (asset, liability, expense, or revenue) to be included in cash flows. The CFO gave us an example of unacceptable noise, as the empty coal trucks were being loaded with the initial batch of coal. To prevent the noise disturbing the local communities, including the local fauna, they designed special rubberized buffer mats to go in the bottom of the coal trucks. The cost of the buffer mats (or other similar treatment for a biodiversity-related problem) would enter the accounts in a dynamic reiterative process, beginning first with the recognition of the biodiversity problem, then evaluating the solution and associated mitigation or restoration cost. Thus, all accounting numbers were market-based values. However, underpinning the analysis for all projects is the analysis of risk. Some of this risk assessment might include the use of more qualitative information, on potential biodiversity impacts and actions to mitigate. This type of assessment is conducted in the very early stages of project development and is necessary part of FCA. The risk information influences strategic decisions and thus, the completeness of FCA.

On one of our subsequent visits, we met with the CFO and the Strategic Asset Manager and discussed some of the strategies around biodiversity impacts. As indicated, the coal mining company is in a position that requires them to confront biodiversity issues right at the beginning of the project. Even the purchase of land is tenuous, as this does not necessarily mean mining approvals in the future and leaves them with stranded assets to account for. We discussed the accounting techniques taken from the early feasibility stage of the proposition through to inclusion of biodiversity impact costs as cash flows when they were recognized. The Strategic Asset Manager further highlighted the need to be an active participant in the local community and how it helped them to specify the ways in which they would manage their social license to operate. He provided an example of managing the restoration of discontinued mine site. He explained how they actually flooded it to create a large inland lake. The lake was developed into a thriving recreational park, used by the community to host water sporting competitions. This development has helped support the community through tourism, sport, and recreation. There were numerous other examples of projects to support indigenous communities and annual payments to local municipalities as part of their social license to operate.

However, the process was never straightforward, and a politically motivated process. This was particularly noticeable for the coal mining industry as a central contributor to the climate change debate. The mining industry is one of the more highly regulated industries, particularly when it comes to sustainability and biodiversity issues. We witnessed associated angst when the Public Relations Manager arrived late for our joint meeting, having been held up in an earlier meeting with the local government minister. He showed us diagrams of the newly rezoned areas where the majority of previously suitable land for mining had been canceled supposedly by the whim of the minister, complained the Manager. The diagrams now were covered in red no go mining zones after the meeting. The outcome of the regulatory environment, as well as market supply and demand forces, highlights the highly dynamic market that the coal mining organization is operating in.

By way of illustrating how government regulation plays a major role in new mine approvals, an extract is provided in Table22.1 taken from a government approvals document. This extract specifically relates to the biodiversity impacts when establishing a new mine development. In the coal mining company's jurisdiction, the environmental assessment must detail the impact on air quality, noise, transport, flora and fauna, surface and groundwater management, methods of mining, landscape management, and rehabilitation. The mining companies are also required to undertake extensive public consultation, which results in specific investments in community infrastructure, to meet local preferences.

Water surplus in initial years (i.e., years 15) of 174ML/annum is predicted under average climatic conditions. Surpluses will be controlled by reducing pump from the northern borefield and by designing the mater management system to contain runoff during high rainfall events;

Water deficits of 599ML/annum in the remainder of the operating years are predicted under average climatic conditions. Deficits are intended to be met by accessing additional water under a modified Water Sharing Agreement.

A key issue highlighted in Table22.1 is the notion of the biodiversity market through the biodiversity-offset strategy. An important part of this assessment process requires mining companies to buy offsets relating to biodiversity issues. As indicated in Appendix 22.1, abiobanking scheme exists to facilitate this.

A key aspect of this scheme is a biodiversity assessment methodology which provides values for threatened species, populations, ecological communities, and their habitats. The biodiversity assessment methodology assesses the biodiversity values in terms of the loss of biodiversity or gain in biodiversity values from management actions. Actions might include retention of native vegetation, dead timber, rocks, and natural water flows; replanting or supplementary planting where regeneration is insufficient; management ofsoil erosion as well as others such as weed control and management of fire, pests, and human disturbance.

In addition to valuing biodiversity losses/gains, the methodology also establishes the circumstances in which biodiversity values can be offset or not by the retirement of biodiversity credits. There are two classes of biodiversity credits calculated: ecosystem credits and species credits. The methodology includes calculations on the number and type of ecosystem credits and species credits that are created when offsetting losses by the improvement of biodiversity values at a designated biobank site.

The valuation model includes the valuation of both direct and indirect biodiversity impacts. Indirect impacts involve the valuing of impacts on water quality and subsequently downstream biodiversity values; increased light or noise that may affect threatened species habitat; or development that may restrict movement of threatened species or populations in surrounding areas. Included in the impact assessment is the demonstration of corporate measures taken to minimize these negative impacts (i.e., controls to prevent erosion; noise and light barriers or structures to allow movement of threatened species or populations). The need for mining companies, such as coal mining company to value, price, and pay for such biodiversity impacts, illustrates the important use of FCA techniques and potential demand for FCA as offsetting grows.

However useful the Appendix 22.1 model might appear, in practice, it was not used by the coal mining company either. While it was required to identify, value, and price its biodiversity effects, the current model for doing this through the biobanking scheme was considered relatively unworkable at the organizational and project level (a point also noted by Madsen etal., 2010, 2011). The Public Relations Manager explained how they had used the model and conducted all the calculations, as suggested. However, he claimed no one had used the model as the price of purchasing and equivalent offset site was three times less costly than the upfront payment required by this scheme. This resulted in coal mining company acquiring offset properties, like those offered by the municipal council, with market-based calculations made outside the model. Although the model was used for comparative purposes, like the municipal council, it was not part of the accountant's repertoire and was largely used by managers to highlight variances for improved resource allocation decisions. Nevertheless, given growing demand for ecosystem credits, this model might end up being the last option for buyers, if there has been a saturation of all equivalent sites for purchase outside the scheme,inperpetuity. Thus, if the model's calculations are accurate, prices have the capacity to increase, at least threefold. Increasing competition and decreasing profits (for buyers and sellers when biodiversity credits are exhausted) is indicative of a developing marketfor biodiversity.

Problems from coal mining include injuries and chronic lung disease in miners, acid mine drainage, unrestored mining sites, dumping hilltops into neighboring valleys, air pollution, erosion, mining waste, subsidence, and disruption in underground water flows and storage. The environmental aspects of mining have received little analysis.

U.S. coals vary in moisture content (2 to 40%), sulfur content (0.2 to 8%) and ash content (5 to 40%). The energy content varies from lignite to sub-bituminous to bituminous coal. The ORNL-RFF study looks at two levels of sulfur content (0.7% and 2.1%). The NREL and ANL studies focused on high-sulfur coal (Illinois #6), providing no information about the range of coals currently used in the United States.

The ORNL-RFF study assumed that the coal came from surface mining. The NREL study examined the impacts of underground (longwall) and surface (strip) mining but concluded that the results were not significantly different. The ANL study assumed underground mining but did not conduct a full analysis of the impacts of mining.

Research by geographers on the mixed effects of coal mining dates back to at least the early 1950s. Initially, this work focused on the eastern United States, but by the late 1970s and 1980s it had shifted to the arid West (along with an increasing share of the coal production). This research analyzed the potential socioeconomic impacts of boomtown development of coal or synthetic fuels. The declining economic fortunes of some of the eastern coal mining areas such as anthracite towns of Pennsylvania continued to receive attention in the 1980s. Regional inputoutput (IO) analysis was demonstrated to be an especially useful tool for analyzing economic effects of spatial shifts in the coal industry. Similarly, most coal research in Britain during this period focused on the uneven economic development or shift between declining and developing regions and a short-lived effort to revive the industry. When U.S. western energy resource development plans were scaled back, research emphasis shifted to the economic and ecological effects and control of acid rain emissions of SO2 and NOx. This subject continued to receive the attention of a few geographers through the 1990s as the Acid Rain Program of the Clean Air Act Amendments was implemented, including (interstate) SO2 allowance trading.

Many energy geographers have examined the socioeconomic and environmental effects and planning issues surrounding petroleum development in disparate regions such as the Middle East, Scotland, Norway, and the U.S. Gulf Coast. The U.S. studies have also considered impact mitigation in the context of the National Environmental Policy Act and the macroeconomic effects of a future large supply disruption by OPEC. Econometric analyses by geographers for the United States have shown since 1989 that policies to expand domestic oil production would have adverse economic and ecological effects. Although less sweeping in its findings, a regional economic analysis in Canada of potential oil resource development in the nearby Beauford Sea found that little or none of the net economic benefits would accrue to Canada's Northwest Territories. This research used a multiregional IO model.

Coal and iron ore formed the basis of the steel industry in Lige in present Belgium. Coal mining rights were granted in Lige in 1195 (or 1198?) by the Prince Bishop. At about the same time, the Holyrood Abbey in Scotland was granted coal mining rights. A typical medieval situation involved abbeys or cloisters driving technology. In France, a 13th-century real estate document established property limits defined by a coal quarry. The earliest reliable written documentation in Germany appears to be a 1302 real estate transaction that included rights to mine coal. The transaction covered land near Dortmund in the heart of the Ruhr.

Coal use started before it was documented in writing. Religious orders tended to keep and preserve written materials more reliably than others. It seems reasonable to postulate that coal use began no later than the 12th century in several West European countries. Documented evidence remains anecdotal for several more centuries but indicates that coal use increased steadily from the 12th century on. England led in coal production until late in the 19th century. Contributing to this sustained leadership were that wood (and hence charcoal) shortages developed earlier and more acutely there than in other countries, there was ready access to shipping by water (sea and navigable rivers), and large coal deposits were present close to the surface.

By the 13th century, London imported significant amounts of coal, primarily sea-coal, shipped from Newcastle-upon-Tyne. The use of coal grew steadily, even though it was controversial, for what now would be called environmental impact reasons. Smoke, soot, sulfurous odors, and health concerns made it undesirable. From the 13th century on, ordinances were passed to control, reduce, or prevent its use. None of these succeeded, presumably because the only alternatives, wood and charcoal, had become too expensive, if available at all. Critical for the acceptance of coal was the development of chimneys and improved fire places. By the early 1600s, sea-coal was the general fuel in the city. The population of the city grew from 50,000 in 1500 to more than 500,000 by 1700, the coal imported from less than 10,000tons per year to more than 500,000tons.

Early coal use was stimulated by industrial applications: salt production (by brine evaporation), lime burning (for cement for building construction), metal working, brewing, and lesser uses. By the late Middle Ages, Newcastle exported coal to Flanders, Holland, France, and Scotland.

By the early 16th century, coal was mined in several regions in France. In Saint tienne, long the dominant coal producer, coal was the common household fuel, and the city was surrounded by metals and weapons manufacturing based on its coal. Legal and transportation constraints were major factors in the slower development of coal on the European continent compared to England. In the latter, surface ownership also gave subsurface coal ownership. In the former, the state owned subsurface minerals. Notwithstanding royal incentives, France found it difficult to promulgate coal development on typically small real estate properties under complex and frequently changing government regulations. Only late in the 17th century did domestic coal become competitive with English coal in Paris, as a result both of the digging of new canals and of the imposition of stiff tariffs on imported coal. Coal mining remained artisanal, with primitive exploitation technology of shallow outcrops, notably in comparison with the by this time highly developed underground metal mining.

The earliest coal mining proceeded by simple strip mining: the overburden was stripped off the coal and the coal dug out. As the thickness of the overburden increased, underground mines were dug into the sides of hills, the development of drift mines. Mining uphill, strongly preferred, allowed free water drainage and facilitated coal haulage. Some workings in down-dipping seams were drained by driving excavations below the mined seams.

Shafts were sunk to deeper coal formations. When coal was reached, it was mined out around the shaft, resulting in typical bell pits. Coal was carried out in baskets, on ladders, or pulled out on a rope. Where necessary, shafts were lined with timber.

In larger mines, once the coal was intersected by the shaft, headings were driven in several directions. From these, small coal faces were developed, typically about 10ft wide, usually at right angles from the heading, and pillars, blocks of coal, were left in between these so-called bords, the mined-out sections. Pillar widths were selected to prevent roof, pillar, and overburden failure, which could endanger people and could lead to loss or abandonment of coal. Each working face was assigned to a hewer, who mined the coal, primarily with a pick. The hewer first undercut the coal face: he cut a groove along the floor as deep as possible. He then broke out the overhanging coal with picks, wedges, and hammers. Lump coal was hand loaded into baskets, usually by the hewer's helper. The baskets were pushed, dragged, or carried to and sometimes up the shaft. This haulage commonly was performed by women and children, usually the family of the hewer. The hewer operated as an independent contractor. He was paid according to the amount of coal he and his family delivered to the surface. Once established as a hewer, after multiple years of apprenticeship, the hewer was among the elite of workers in his community.

In deeper or better equipped mines, the coal baskets or corves were hoisted up the shaft using a windlass, later horse-driven gins. These also were used for hoisting water filled baskets or buckets, to dewater wet mines. By the end of the 17th century, shaft depths reached 90 ft, occasionally deeper. Encountering water to the extent of having to abandon pits became frequent. Improving methods to cope with water was a major preoccupation for mine operators.

Ventilation also posed major challenges. Larger mines sank at least two shafts, primarily to facilitate operations. It was recognized that this greatly improved air flow. On occasion shafts were sunk specifically to improve ventilation. During the 17th century, the use of fires, and sometimes chimneys, was introduced to enhance air updraft by heating the air at the bottom of one shaft. In fiery mines, firemen, crawling along the floor, heavily dressed in wetted down cloths, ignited and exploded gas accumulations with a lighted pole. This practice was well established in the Lige basin by the middle of the 16th century. As mines grew deeper, and production increased, explosions became more frequent, on occasion killing tens of people.

In North America, coal was reported on Cape Breton in 1672. Some coal was mined for the French garrison on the island, some was shipped to New England before 1700. Coal was found by Joliet, Marquette, and Father Hennepin, in 1673, along the Illinois river. It is possible that some was used at that time by the Algonquins in this area.

The size and complexity of the electricity supply industry meant that there could never have been any doubt that it would be the most difficult privatisation attempted. The asset value of the UK electricity supply industry was estimated to be approximately 'four times as large as the total asset base of all the industries which were privatised in the first two Thatcher terms' (Holmes et al., 1987). Instead of dealing with just one company, as was the case with telecommunications and gas, the electricity supply industry for England and Wales was made up of 14 companies, 12 regionally based distribution companies, the CEGB and the Electricity Council. In addition, with electricity demand-growth limited (see Table III.1), the new companies would only be able to grow by diversifying or competing successfully with each other.

While the government was clear about what it did not wanta simple transfer of assets from public to private ownership with no new competitive mechanismsit was far from clear about what it did want. Despite contemplating momentous changes to one of the most fundamental sectors of the economy, there was no vision of how the final structure would look, nor has there been a constant guiding hand providing continuity. The Conservative Party manifesto of 1987 contained a commitment to privatise the electricity supply industry, but few details on how it would be done. It also contained a commitment to promote nuclear power development, a commitment which many predicted would be difficult to reconcile with privatisation (Chesshire, 1989).

A clear additional goal behind privatisation was to break once and for all the power of the coal-mining unions. Whilst this was not admitted at the time, subsequent memoirs from the Cabinet Ministers involved have confirmed this motive.6 The protected market for British coal could not be expected to be sustained in a private competitive system, and private companies would not be so vulnerable to the political pressures which weakened the electricity supply industry's negotiating position against the British coal industry.

The election manifesto commitment effectively meant that the electricity supply industry had to be sold. The option that, after careful consideration, retaining the industry in public ownership was the best choice was not one that was available to the Secretaries of State for Energy charged by Mrs Thatcher with carrying through the process. Decisions which could be represented as policy 'U-turns' had become anathema to the Conservative Government, and the Treasury could not be denied its pound of flesh. In addition, the process of privatisation would have to be completed within the time span of one Parliament. Any possibility that the process would have remained uncompleted when a General Election was held would have been far too risky, both politically and commercially. The revenues accruing could also be used to party-political advantage by cutting taxes just prior to a General Election. While a British Parliament can run for up to five years, in general the period between elections (which is largely at the discretion of the Government) is usually expected to be no more than four years. Allowing for the period leading up to an election when little of substance can be accomplished, and that the structure had not been chosen in 1987, this meant that the whole process, from design of the new structure to sale of the companies, had to be crammed into a period of less than four years.

The government's February 1988 White Paper on privatisation finally gave some details of the structure proposed (Department of Energy, 1988; Scottish Office, 1988). The distribution companies, renamed Regional Electricity Companies (RECs), would be sold intact. However, they would be required formally to separate the distribution business, that is the operation of the local physical infrastructure (the 'wires business') from the supply business, that is the purchase of electricity, marketing, meter-reading and consumer billing. The wires business was seen as a natural monopoly, while the supply business could be opened to competition.

The CEGB would be divided into three parts. The generation side would be split into two competing companies, one containing 70% of capacity, including the nuclear plant, and the other containing 30% of capacity. The transmission business, seen as a natural monopoly, was to be operated as a third separate company.

As with previous privatisation of utility industries, regulation, where necessary, would be under the aegis of a Director General, in this case, of Electricity Supply (the DGES), with the assistance of a specific new regulatory body, the Office of Electricity Regulation (OFFER). It was assumed that much of the industry, including generation and ultimately supply, would be sufficiently competitive not to require formal regulatory procedures, but where formal price regulation was required, in the distribution and transmission sectors and initially in supply, it would be based on incentive regulation using the simple 'RPI x' formula. 'RPI', or retail price index, is a measure of consumer price inflation, and 'x' is an incentive term. Put simply, this means that the price of the elements under the control of the utility are allowed to rise by the general rate of inflation minus a small term which the utility must cover by improving its efficiency. Any changes in the cost of the elements of the total price which are seen to be outside the control of the utility can be passed on in full to consumers.

The basic philosophy underlying the new structure was that all areas of electricity supply which are not natural monopolies would be opened to full and vigorous competition as soon as was practical. The remaining area, which amounts to the physical infrastructure of the network, the high-voltage transmission system and the local distribution system, would be regulated by the DGES, using incentive regulation.

The most obvious area which could be opened to competitive forces was generation. The Power Pool was to be the main price-setting arena contracts of limited term outside the Pool were anticipated for power purchasers who needed greater predictability in their costs, but pricing of these contracts would tend to use Pool Prices as their bench mark. These mechanisms were expected to be competitive enough that no need for routine regulation of the generation sector was anticipated. Market forces were also expected to remove the need for planning generation capacity.

It was also anticipated that elements of the supply of power to final consumers could be made fully competitive. Clearly there was no question of duplicating the physical distribution infrastructure, but if the network was a resource open to all, on non-discriminatory terms, competition could be introduced. For example, if a supply company could purchase power more economically, or it could supply customers incurring lower overheads, it would be able to offer cheaper terms to consumers. From Vesting Day, April 1,1990, (the day the new structure came into being), consumers with demand greater than 1MW were able to negotiate their supply from any licensed supplier. This limit was reduced to 100kW in April 1994, and is scheduled to be removed altogether in April 1998. Customers negotiating the supply of power on individual contracts are assumed to have open to them a sufficiently competitive market that regulation is not required. However, as a backup for those not wishing to exercise choice, the local REC is obliged to offer supply to all consumers with demand less than 10MW under the terms of a published and regulated tariff.

Details of how the system would run in practice were still sketchy at this point, but a number of factors conditioned the structure and how it was ultimately made operational. Some of these have been discussed earlier, including the need for the new structure to be competitive and the necessity to complete privatisation within one Parliamentary term. Other factors are detailed below.

The Conservative Party's manifesto commitment to nuclear power was noted earlier. This stems in part from the fact that, as with many right- of-centre parties worldwide, the Conservative Party has always tended to be well disposed towards nuclear power. In addition, the defeat of the coal-miners' strike in 1985 was in no small part due to the contribution of nuclear power,8 and the Conservative Party was seen to owe nuclear power a debt. Privatisation was not expected to help the nuclear industry by itselfthe CEGB was already fully committed to nuclear powerbut protection for the nuclear industry had to be built into the new structure. Indeed, thinking on the generation side was based almost entirely on finding a structure which would allow nuclear power to flourish.

By contrast, there was a long history of animosity between the Conservative Party and the main coal-miners' union, the National Union of Mineworkers (NUM), particularly following two strikes in the early 1970s and other disputes which inflicted serious political damage on the Conservative Party. The Conservative Party was unhappy about the high dependency of the electricity supply industry on coal (about 80% of power was generated using British coal) which seemed to give miners scope to thwart Government wishes by the use of industrial action. While the wish to break the power of the NUM could not be stated in those terms, the Government used code-words such as 'diversification' which few failed to decode (Lawson, 1992, p. 168).

The Department of Energy in the UK was not regarded as one of the more effective government departments, and it is significant that since it was abolished following the General Election in 1992, there has scarcely been a voice raised lamenting the loss. The most crushing indictment of its lack of understanding of the sector was its failure to alert the government to the total impracticality of the plans to privatise nuclear power. The private sector, with little experience of dealing with nuclear power, was no more impressive, and investment analysts did little to alert the government to the problems in its approach.

In part, this was a reaction against the US system of economic regulation, which was perceived to be cumbersome, bureaucratic and expensive and was too dominant a force in utility decision-making. There was also perhaps a genuine belief that a market could be created which was competitive enough not to require heavy regulation. More practically, from the point of view of public presentation, it would have been difficult to argue that the private sector had major advantages over public ownership if a heavy regulatory structure was required to ensure that the private sector did not abuse its market power.

coal mining | mcr safety

coal mining | mcr safety

Marco Polo was one of the first Europeans to see and describe coal being used in China during his Asian travels. Since Polos travels in the 13th century, this burning coal log has kept countless people warm during cold, frigid months. However, when it pertains to actual coal mines, there is a dark side and it goes beyond the actual darkness found inside underground mines. According to the BLS, a coal miner is twice as likely to be injured when compared to the private industry. When you look specifically at underground mining, a worker is four times as likely to be hurt.

In addition, there is always the possibility of being trapped, like the 33 Chile miners who were trapped for 69 days back in 2010. The good news is that safety injuries have drastically come down over the past 40 years. Since 2007 alone, the rate of injuries has dropped from 4.3 to 2.6 for every 100 employees.

MCR Safety is doing our part by constantly innovating safety gear that matches the needs of coal miners. Max 6 Anti-Fog technologyis a new innovation the coal industry has embraced, due to its 6X greater AF dissipation properties. With flying particles all around, there is great risk for miners taking eyewear off due to fogging. With the Max 6 PD1210PFD4 dust rated goggle, coal miners no longer need to remove their safety gear! Check out our Max 6 pagefor more on this technology.

Greek philosopher Aristotle once referred to coal as a charcoal like rock. Well, he was not far from the truth. Coal is the fuel powering our modern day electrical power plants. It produces the needed steam to drive the massive turbines responsible for creating electricity. Ever since the creation of the steam engine and the Industrial Revolution, coal has served as the fundamental building block for our modern world.

The two mining methods used in coal extraction are surface Open Pit mining and Underground mining. Simply put, surface mining is peeling back the earth and collecting coal near the surface. Whereas, underground mining requires tunneling and building shafts. The mining method chosen by companies depends on the coal deposit being extracted. The deeper the mine goes, the more hazards workers face.

The continuous mining method, an innovation from the late 19th and 20th century, eliminates the drilling and blasting operations found in conventional mining. This method uses a machine called a continuous miner. It continually extracts the coal, while loading onto a conveyor system.

Tend conveyors or conveyor systems that move materials or products to and from stockpiles, processing stations, departments, or vehicles. There are roughly around 600 of these workers found in Coal Mining. You will find these workers loading materials, clearing jams, and removing damaged materials. Common Job titles for this position are Chipper Operator, Flumer, Process Operator and Strapper Operator.

Perform tasks involving physical labor at construction sites. Mining examples include earth drillers, blasters and explosives workers, derrick operators, and mining machine operators. There are roughly around 22,000 of these workers found in Coal Mining. You will find these workers using hand tools, repairing drilling equipment, and transporting materials. Common Job titles for this position are Coal Miner, Mining Technician, Underground Miner, Helper, Laborer, Post Framer, and Construction Worker.

Operate mining machines that rip coal, metal and nonmetal ores, rock, stone, or sand from the mine face and load it onto conveyors or into shuttle cars. There are roughly around 3,500 of these workers found in Coal Mining. You will find these workers assisting in construction activities, checking the roof stability and cleaning equipment. Common Job titles for this position are Bore Mine Operator, Miner Operator, and Continuous Miners.

Operate dredge to remove sand, gravel, or other materials in order to excavate and maintain navigable channels in waterways. There are roughly 4,000 of the workers found in Coal Mining. You will find this worker operating equipment, tools and gauges. Common Job titles for this position are Dredge Operator and Dredger.

Install, maintain, and repair electrical wiring, equipment, and fixtures. Around 2,200 of this occupation found in Coal Mining. You will find these workers connecting wires to breakers and transformers, making dielectric and FR safety gear important. Common Job titles for this position are Industrial Electrician, Journeyman Electrician and Wireman, and Maintenance Electrician.

Operate machinery equipped with scoops, shovels, or buckets, to excavate and load loose materials. There are around 3,000 of these workers in the Coal Mining industry. You will find these workers breaking rock and operating power shovels. Common job titles for this occupation are Pit Operator, Loader Operator, and Dragline Oiler.

Help craft workers by supplying equipment, cleaning areas, and repair drilling equipment. Extraction craft workers are earth drillers, blasters and explosives workers, derrick operators, and mining machine operators. There are around 10,000 of these workers. Common Job titles for this position are Blasting Helper, Miner Helper, and Driller Helper.

Repair overhaul mobile mechanical, hydraulic, and pneumatic equipment. Examples of this equipment includes cranes, bulldozers, graders, and conveyors. There are around 2,800 of these workers found in Coal Mining. You will find these working replacing worn parts and reassembling heaving equipment with tools. Common Job titles for this position are Heavy Equipment Technician, Field Mechanic, and Mobile Heavy Equipment Mechanic.

Worker activities include repairing, installing, and adjusting industrial machinery. Around 1,000 of this occupation works in Coal Mining. You will find these workers cuttingand welding metal to repair broken metal parts. Job titles for this position are Fixer, Industrial and Master Mechanic.

Operate underground loading machine to load coal, ore, or rock into shuttle / mine car or onto conveyors. There are around 1,000 of these workers are found in Coal Mining. You will find these prying off loose material from roofs, cleaning hoppers, and cleaning spillage. Common Job titles for this position are Miner, Production Miner, Shuttle Car Operator, and Under Ground Miner.

Operate machines designed to cut, shape and form metal. There are roughly 600 employees found for this occupation. You will find this worker fabricating metal products, lifting heavy material and working with their hands. Common job titles for this position are sheet metal worker and welder. Be sure to check out our Metal Fabrication industry educational page.

Keep machines, mechanical equipment, or the structure of an establishment in repair. There are around 8,500 of this occupation working in Coal Mining. You will find these workers pipe fitting, repairing equipment, and repairing buildings. Job titles for this position are Maintenance Worker, Maintenance Mechanic, and Facilities Manager.

Help move steel and other materials. Around 10,000 of these workers help move steel and other material across in Mining. That is a large number of hands needing protected. You will find these workers operating conveyors, transporting material, and operating machines. Common job titles are laborer and operator.

Operate machinery such as longwall shears, plows, and cutting machines to cut or channel along the face or seams of coal mines, stone quarries, or other mining surfaces to facilitate blasting, separating, or removing minerals or materials from mines. There are roughly around 1,700 of these workers found in Coal Mining. You will find these workers positioning roof supports, preventing cave-ins and cutting entries between rooms. Common Job titles for this position are Bore Miner Operator, Underground Miner and Shear Operator.

Operate diesel or electric-powered shuttle cars in underground mines to transport materials from working face to mine cars or conveyors. There are roughly around 1,300 of these workers found in Coal Mining. You will find these workers attaching drill bits and drill rods.. Common Job titles for this position are Coal Haul Operator and Shuttle Car Operator.

Repair, or overhaul mobile equipment, such as cranes, bulldozers, graders, and conveyors, used in construction, logging, and surface mining. There are roughly around 2,800 of these workers found in Coal Mining. You will find these workers replacing worn parts and reassembling equipment using hand tools. Common Job titles for this position are Heavy Equipment Technician, Field Mechanic, and Equipment Mechanic.

Operate machinery to install roof support bolts in underground mine. There are around 2,700 of this occupation working in coalmines, essentially the majority of this entire occupation. You will find these workers pulling down loose rock, drilling holes and positioning machines. Job titles for this position are Bolt Man, Bolter, and Underground Miner.

Operate welding, soldering or brazing machines that weld, braze, or heat treat metal products. The mining industry employs around 620 of these workers in coal mining. You will find these workers adding material to work pieces, joining metal components, and annealing finished work pieces. Common Job titles for this position are Fabricator, Mig Welder, Spot Welder, Fitter-Welder, and Braze Operators.

Use hand-welding, flame-cutting, hand soldering, and brazing equipment to weld/join metal components, fill holes, indentations, or seams of fabricated metal products. There are around 600 of these workers employed in coal mining. You will find these workers welding components in flat, vertical or overhead positions. Common Job titles for this position are Maintenance Welder, Mig Welder, and Welder/Fabricator.

As mentioned above, the hazards coal miners face are endless. A safe working environment ensures workers return home unharmed, while also creating a productive and profitable mining operation. Weve got you covered with gloves, glasses, and garments needed in todays coal mine. After all, keeping people protected is what we do. Let MCR Safety help protect you the next time you enter a mine!

Numerous mining injuries occur from working around low roofs, confined spaces, shoveling, lifting, and climbing. We have highly abrasive gloves for this very reason.

Impact in confined spaces, impact from crush and other mining equipment, heavy tool handling, falling rocks, tire changing, using grinding equipment and loading materials can all be hard on the back of a workers hands.

Mining underground and tearing into the earth is just a little dirty at times. Mining coveralls for underground mines and raingear for outdoor surface mining are absolute necessities.

Many workers drive equipment in mining operations. Many mining fatalities occur due to Haul-Truck accidents. Drivers should not even second-guess wearing premier leather driver gloves.

Dirt and dust are virtually in all mining environments. Drilling, blasting, and dust generated from hauling trucks are dust creators. Dust is known as one of the top on-the-job health risks of mining.

Mine sites use a lot of heavy trucks, hydraulics, conveyors, bulldozers and equipment. Mechanics need excellent abrasive grip and many times require back-of-hand protection.

Breaking up rock, drilling, and mining the earth creates flying particles. Grinding residues are present too. Check out eyewear designed for this exact scenario.

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