The cast steel spider cap has been designed to serve as a feed distribution plate for coarse materials. It is recessed on the 22, 30, 36 and 48-in. crushers. For fine materials, the wobble plate feeder a more effective means of distributing the feed is recommended.
The annealed cast steel top shell and spider are made in one piece. The spider is of the three arm type, equipped with a self-aligning, Scor-Proof plastic ball and socket bearing in crusher sizes 22 to 48-in., and with an hourglass type bearing in sizes above 48-in. The lubricant is sealed in with a garter type oil seal. Bearings can be lubricated from outside the topshell on the 51, 60 and 84-in. crushers through oil holes in spider caps of the four smaller sizes.
The mainshaft is of high grade forged steel, annealed for stress relief. It is tapered to gauge for head center fit. The bottom of the shaft is fitted with a polished bronze step bearing. The journal for the spider bearing is formed by a sleeve shrunk on the shaft on the 51, 60 and 84-in. crushers. Short, heavy mainshaft design results in long life.
The step bearing consists of a bronze mainshaft step, a bronze piston wearing plate, and an alloy steel washer between the two. The washer is drilled for oil cooling and lubrication. Both the mainshaft step and the piston wearing plate are made of high lead bronze, selected to give the best bearing surface. The washer and plate are pinned in place, and the bearing surfaces are grooved to permit distribution of the lubricating oil.
The Mantalloy head mantle of this cone crusher is a replaceable wearing surface. It is made of alloyed manganese steel, and is held in place with a self-tightening head nut. On the 51-in. Hydrocone crushers and larger, the bottom portion of the mantle is ground to gauge to fit the head center, and the top portion is zinced. For crushers smaller than 51-in., the entire inner surface of the mantle is ground to gauge and no zincing is required.
The Mantalloy concave ring, or the stationary crushing surface, is available in three standard types, coarse, intermediate and fine. Helices, cast into the bottom of the concave ring, engage similar helices on the top of a cast steel concave support ring. The support ring is held by a key to the top shell to facilitate assembly, after which it is supported on the bottom shell. The helical surfaces make the concave ring self-tightening; no zincing is required.
The dust seal is a plastic ring suspended in a housing from the head center and encircling the dust collar. It is designed to accommodate the vertical adjustment and the gyrating and rotating motion of the head. All wearing parts are replaceable. The crusher is fitted with a connection for introducing low pressure air inside the seal for additional dust protection.
The eccentric is made of high carbon cast steel and fitted with a bronze inner wearing sleeve. The eccentric turns in a bronze bottom shell bushing. Both sleeve and bushing are replaceable. The eccentric throw can be changed in the field by installing a different sleeve.
The alloy steel pinion is mounted on a turned shaft. The cast steel pinionshaft housing is bolted to the machined opening in the bottom shell. It is equipped with anti-friction bearings sealed inside and out, and has separate pool lubrication in all sizes except the 36 and 48-inch machines. The 36 and 48-inch Hydrocone crushers have sleeve type counter-shaft bearings which are lubricated by the external oiling system.
The annealed cast steel bottom shell is of the three arm, open discharge type, bored to gauge for the top shell and eccentric bushing. It is bored and faced for the bottom plate, pinionshaft bearing and dust collar.
The external oil conditioning system furnished with Hydrocone crushers consists of a large oil storage tank on which are mounted a condenser type cooler, pressure type filter, motor, and a pump which pumps the lubricant to the crusher automatically. These units both cool and filter the oil. The accumulator and tank for the Automatic Reset are mounted separately from the oil storage tank.
All oil conditioning systems are equipped with oil flow and temperature safety switches which are adjusted to open the motor circuit and stop the crusher if the temperature becomes too high or if there is not a sufficient flow of oil. Flexible hose connects the lubricating unit to the crushers, greatly reducing the number of pipe fittings required and simplifying the installation.
Oil for the tank is pumped through the filter and cooler to the step bearing and up the inner eccentric bearing. It flows down the outer eccentric bearing, lubricates the gear and pinion, then returns to the tank. Tank capacities vary from 30 gallons for the 22-in. Hydrocone crusher to 240 gallons for the 84-in. machine.
23. Feed Plate 24. Screw 25. Torch Ring 26. Locking Bolt 27. Dust Shell 28. Clamp Ring 29. Adjustment Ring 30. Mainshaft Pin 31. Pin 32. Socket Liner 33. Socket 34. Eccentric 35. Eccentric Bushing 36. Counterweight 37. Counterweight Guard 38. Gear 39. Thrust Bearing 40. Countershaft Box 41. Countershaft Box Guard 42. Oil Finger Cover 43. Oil Finger 44. Countershaft Bushing 45. Countershaft 46. Pinion
CRUSHING CHAMBER may be any one of three standard types (Fine, Intermediate and Coarse) designed to assure a cubical, well-graded product. Shape of mantle and concave ring, and the range of adjustment available, results in maximum life and minimum scrap when replacing parts. Special crushing chambers also available.
BEVEL PINION AND GEAR are of the spiral design in the larger sizes provide greater tooth contact and smooth, trouble-free operation under most severe conditions. Bevel spur and pinion gears are used on smaller size Hydrocone crushers.
INNER CRUSHING CONE or mantle is one-piece Mantalloy casting held in place by a self-locking head nut. Complete contact of the ground inner surface with steel head center eliminates need for zincing in all but the larger sizes.
OUTER CRUSHING RING or concave ring is one-piece Mantalloy casting. Necessity of zincing or clamping concave ring in place is eliminated by ground-to-fit finish on outer surface and the use of an effective self-locking device.
3-PIECE STEP BEARING accommodates gyrating motion of main shaft and transmits crushing pressure to hydraulic piston. Designed to withstand bearing pressures much greater than those encountered in actual service.
While it is one of the major parts in the machine, there are few essential differences between the adjustment ring in the 10 ft. crusher and in the smaller machines, except as to size. Material of the ring which weighs 70,000 pounds is cast steel. Rigidity of the adjustment ring cross-section is essential. In this case, increased section thickness, with ordinary carbon steels, results in a reduction in deflection.
This part, which is screwed into the adjustment ring, is the means of setting of the machine. Adjustment is performed by rotating the bowl relative to the adjustment ring. In the 10 ft. machine provision has been made to adjust the setting during crushing. This increases the availability of the crusher substantially. Past practice had been to stop feed to the crusher during adjustment.
During crushing the position of the bowl and adjustment ring is maintained on the slant flank of the threads by means of the crushing force. The slant flank helps in centering the two elements. The clamp ring acts somewhat like a locking device to take up clearances. Ideally, the clamping cylinders do not have to have any greater capacity than is necessary to overcome the weight of the bowl. Practically, the clamp ring capacity is many times higher to withstand tramp passage.
To adjust the setting of the machine, hydraulic rams are used to rotate or counter-rotate the bowl in the adjustment ring. The seal between the adjustment cap and hopper is a simple, continuous, tightly fitting flap which allows free, relative rotation but prevents intrusion of dust into the thread area. The lower end of the thread connection between bowl and adjustment ring is also sealed. The hopper assembly, which is actually a part of the bowl assembly, including the hopper, hopper liner and cap closure, comprises the section in which the feed is introduced. It includes a dead bed, reducing wear and shock from the fall of the feed from the feeder above.
The adjustment rams are pressurized hydraulically and provide a setting adjustment. For normal adjustment of setting due to wear, installation and removal of the bowl is made through a swivel sheave and a cable turn applied around the adjustment cap. The bowl is then rotated by use of the maintenance crane.
The crushing head, similar in section to that of the 7 ft. machine, had three-dimensional photoelastic studies made using the technique of freezing stresses into a loaded plastic model, sectioning the model and examining the slices under polarized light. As a result of these techniques, stresses have been reduced. The core of the head consists of six massive ribs to support the crushing forces on the surface of the head. The head is cast steel.
The main shaft is of turbine rotor steel of high quality and refinement, the chemistry of which is low carbon to reduce the possibility of heat checking. It includes chrome nickel additions for deep hardening, notch toughness and resistance to fatigue. The shaft extension is provided to reduce the relative strain between the head and shaft and thereby reduce fretting in the fit, which has a heavy press. The shaft diameter is 50 percent greater than the 7 ft. crusher shaft. As a result, the shaft operates at lower values of bending stress and deflection. Reduced deflection produces distinct benefits in bearing behavior because of uniformity of oil film under load. Reduced stresses assure longer life and resistance to overloads.
The head-shaft assembly is supported by the socket and socket liner which is, in essence, a spherical thrust bearing. The function is to carry the vertical component of the crushing force while allowing the head to oscillate around the theoretical center of rotation.
The socket of carbon steel is of dowelled design. The forces between the head and the socket are normal to the spherical surface of the head and pass through the theoretical center. The line of action of these forces is such that practically pure compression is applied to the socket and liner, reducing deflection and stress to a minimum and promoting good bearing performance.
The force distribution throughout the crusher is based on a vector diagram of the cavity forces during crushing and the reactions at various associated loading points in the crusher. The vector diagram establishes their relative magnitude, direction and points of application. The actual magnitude of these forces is established by the crushing force necessary to lift the adjustment ring off the frame seat. This condition represents the maximum allowable force for normal crushing.
A baffle ring attached to the head is sub-merged around its entire periphery in a water trough resting on the socket. Dust tends to settle into the trough and must be continuously removed to prevent caking. For this reason, water is continuously fed through specially designed nozzles which scour the trough. Overflow water is carried off by internal piping and passages. The seal chamber is vented to atmosphere to prevent siphoning which may cause oil contamination of the water or vice versa.
The gears are straight tooth bevel gears and are designed to AGMA standards using a computerized program which, upon input of the basic information, such as DP, diameters, gear ratio, material properties, tooth type, provides a complete printout of the rated power on the basis of tooth strength and surface durability of the gear. The factor of safety on the gear is in excess of three on the strength basis and in excess of two on the durability basis.
A Cone Crusher is a compression type of machine that reduces material by squeezing or compressing the feed material between a moving piece of steel and a stationary piece of steel. Final sizing and reduction is determined by the closed side setting or the gap between the two crushing members at the lowest point. As the wedge or eccentric rotates to cause the compression within the chamber, the material gets smaller as it moves down through the wear liner as the opening in the cavity gets tighter. The crushed material is discharged at the bottom of the machine after they pass through the cavity.
A Cone Crusher will deliver a 4:1 to 6:1 reduction ratio. As we set the closed side setting tighter to create a finer output, we also reduce the volume or throughput capacity of the machine. Generally speaking, multiplying the closed side setting by two is a good guide to the top size of the gradation exiting the machine.
The technology that makes a MSP Cone Crusher outperform competitive cones on the market is the combination of all of the factors of performance i.e. balanced eccentric, higher speeds, fulcrum point position, and stroke. By using sound engineering with years of field testing a truly tried and tested new Cone Crusher has emerged.
A balanced eccentric coupled with a fulcrum point ideally placed over the crushing chamber yields highly effective compression crushing. This allows higher eccentric speeds to maximize performance without disruptive forces. The eccentric stroke is designed to work with the eccentric speed and fulcrum position to produce higher yields and minimize recirculating loads. The torque and resultant crushing forces are as effective as virtually any Cone Crusher on the market.
Spiral bevel gears provide the turning force to the eccentric. The spiral gear is mounted on a sturdy countershaft of the Cone Crusher, which rides in bronze bushings. The gears are precision cut for quiet operation. Misalignment problems are eliminated.
The MSP Cone Crusher features one of the largest volume displacements by a crusher head. When there is a large volume of material displaced this way, it means that more material is crushed in each cycle, more material can be fed to fill the larger void left when the crushing head recedes, and more material flows through the crusher due to the larger throughput and gyrating cycles allowing material to drop further. The benefits of high efficiency, greater crushing force and high capacity coupled with the durability the market expects are the reasons why this design is the best way to increase your productivity and profitability.
Sleeve bearings make removal and installation of the MSP Cone Crusher head and main shaft simple. The tapered main shaft fits into a large opening at the upper end of the tapered eccentric bushing. The shaft does not require precise alignment. It can be inserted from a vertical position and will self-align.
With the MSP Cone Crushers automatic hydraulic overload relief system, the crusher immediately opens in the event of an overload. This action reduces the crushing pressure, allowing the obstruction to pass through the chamber. After the chamber has been cleared, the hydraulic control system automatically returns the crusher to its original setting. Shock loads on the crusher are reduced for longer component life.
MSP Cone Crushers are built to make your operations run more smoothly and easily. Its simple and easy to read control panel provides you with the necessary information to properly run your crusher. For example, the MSP Cone Crusher shows you the exact cone setting to allow the operator to stay on top of a critical set point.
To enhance your Cone Crusher's life and maintain optimal crushing capacities, an automatic liner change reminder is included for your convenience. When the new mantle and liners are installed, the automated reminder is reset. As the crusher operates, the system will track production capacities and calculate the liner wear rate. When the cone liners reach the maximum wear point, it sends a flashing reminder to 'change cone' on the cone setting meter. After the wear parts are changed, simply reset the automated reminder system and continue efficient, reliable crushing.
The MSP Cone Crushers are built heavier than most competitive Cone Crushers. The extra weight means lower stress on the machine, which results in longer operational life. There is no question that the proper use of mass makes for more durable crushers. Additionally, a broad array of manganese liners is offered for each size MSP Cone. A unique and patented feature allows the Liners to fit without the use of any backing material. Improved Chamber matching with crusher feeds virtually eliminates any trial and error.
All these factors combine to give producers more effective compression crushing. This reduces liner wear, which reduces wear cost and allows higher yields, resulting in decreased overall cost per ton of finished product.
In the Symons principle, which is utilized by the MSP Cone Crusher, each cycle is timed so that the feed material and the upward thrust of the crushing head meet at the moment of maximum impact. The optimum speed of gyration and the large eccentric throw produce two important results: 1) the rapidly closing head catches the falling feed material and delivers the extremely high crushing force and 2) on the other side of the chamber the rapidly receding head allows material to fall freely to the next point of impact or exit the chamber. The combination of superior crushing force and free flow of material in the MSP Cone Crusher results in production levels that are unsurpassed and means lower power consumption per ton.
Ten years of testing went into the final combination of speed, stroke, and head angle to deliver the most efficient use of power. Greater efficiency delivers lower power consumption, reduced cost per ton, less maintenance and higher profits.
The power input imparted by the driven eccentric results in a bearing force in opposition to the crushing force at a point on the lower portion of the main shaft. The bearing force as it is transmitted to the main shaft provides the required moment to crush the rock. The distance between the bearing force and the fulcrum point is called the force arm. The longer the force arm, the greater the momentum, which produces a greater crushing force.
Crushing loads are distributed over a large spherical bearing. The socket liner keeps full contact with the crushing head ball and carries all of the vertical component and part of the horizontal. The long force arm, represented by the main shaft, reduces the load transmitted through the eccentric bushing.
Capacities and product gradations produced by Cone Crushers are affected by the method of feeding, characteristics of the material fed, speed of the machine, power applied, and other factors. Hardness, compressive strength, mineral content, grain structure, plasticity, size and shape of feed particles, moisture content, and other characteristics of the material also affect production capacities and gradations. Gradations and capacities are most often based on a typical, well-graded choke feed to the crusher. Well-graded feed is considered to be 90% to 100% passing the closed side feed opening, 40% to 60% passing the midpoint of the crushing chamber on the closed side (average of the closed side feed opening and closed side setting), and 0 to 10% passing the closed side setting. Choke feed is considered to be material located 360 degrees around the crushing head and approximately 6 above the mantle nut. Maximum feed size is the average of the open side feed opening and closed side feed opening.
Minimum closed side setting may vary depending on crushing conditions, the compressive strength of the material being crushed, and stage of reduction. The actual minimum closed side setting is that setting just before the bowl assembly lifts minutely against the factory recommended pressurized hydraulicrelief system.
Overall, industry acceptance of the Symons principle and performance, the McLanahan Cone Crusher works to deliver lower recirculating loads at higher tonnage rates with lower maintenance costs by combining:
A general rule of thumb for applying Cone Crushers is the reduction ratio. A crusher with coarse style liners would typically have a 6:1 reduction ratio. Thus, with a 34 closed side setting, the maximum feed would be 6 x 34 or 4.5 inches. Reduction ratios of 8:1 may be possible in certain coarse crushing applications. Fine liner configurations typically have reduction ratios of 4:1 to 6:1.
The difference between the volume displaced by the crushing head when it is fully closed and fully open is called the displacement volume. A large displacement volume results in greater capacity because:
In order to maintain the maximum levels of capacity, gradation, and cubical product, a Cone Crusher must be choke-fed at all times. The best way to keep a choke-feed to the ConeCrusher is with a surge bin (or hopper) and feeder that are located prior to the crusher. Choke-feeding is almost impossible to achieve without a hopper and feeder.
There are a number of different criteria to consider when selecting the right chambers for your crushing needs. However, the one that must always be considered isthat you have a well-graded feed to the chamber. A well-graded feed is generally thought to be 90 to 100% passing the closed-side feed opening, 40 to 60% passing the midpoint, and 0 to 10% passing the closed-side setting.
One thing you should never do is place a new concave liner in a crusher with a worn mantleor place a new mantle in a crusher with a concave liner. Why? If you have properly selected the replacement component, you will change the complete profile of the Cone Crusher by mating new and worn components. The receiving opening will tend to close down, restricting the feed from entering the chamber and causing a reduction in tons per hour.
If the liner is wearing evenly throughout the chamber, you should consider changing out the manganese when it has worn down to about 1" (2.5 cm) thick at the bottom. At about 3/4" to 5/8" (1.9 to 1.6 cm) thick, the manganese will crack, causing the backing material to begin to disintegrate. This, in turn, will cause the liners to break loose. If this should happen, continued operation could destroy the seat on the support bowl or the head of the Cone Crusher.
McLanahan Symons Principle (MSP) Cone Crushers utilize a combination of improved factors of performance, which are enhanced by the Symons Principle of crushing, as well as the latest hydraulic features and electrical features that create a modern, efficient, reliable and durable Cone Crusher that ultimately leads to a faster ROI. MSP Cone Crushers are designed to make your operation run more smoothly and easily, as well as ensuring lower operating costs and minimal downtime so that MSP Cone Crushers are more frequently fully operational and processing optimal amounts of material.
Efficiency can be defined by the ratio of the work done by a machine to the energy supplied to it. To apply what this means to your crusher, in your reduction process you are producing exactly the sizes your market is demanding. In the past, quarries produced a range of single-size aggregate products up to 40 mm in size. However, the trend for highly specified aggregate has meant that products have become increasingly finer. Currently, many quarries do not produce significant quantities of aggregate coarser than 20 mm; it is not unusual for material coarser than 10 mm to be stockpiled for further crushing.
Cone crushers were originally designed and developed by Symons around 1920 and therefore are often described as Symons cone crushers. As the mechanisms of crushing in these crushers are similar to gyratory crushers their designs are similar, but in this case the spindle is supported at the bottom of the gyrating cone instead of being suspended as in larger gyratory crushers. Figure5.3 is a schematic diagram of a cone crusher.
The breaking head gyrates inside an inverted truncated cone. These crushers are designed so that the head-to-depth ratio is larger than the standard gyratory crusher and the cone angles are much flatter and the slope of the mantle and the concaves are parallel to each other. The flatter cone angles help to retain the particles longer between the crushing surfaces and therefore produce much finer particles. To prevent damage to the crushing surfaces, the concave or shell of the crushers is held in place by strong springs or hydraulics which yield to permit uncrushable tramp material to pass through.
The secondary crushers are designated as Standard cone crushers having stepped liners and tertiary Short Head cone crushers, which have smoother crushing faces and steeper cone angles of the breaking head. The approximate distance of the annular space at the discharge end designates the size of the cone crushers. A brief summary of the design characteristics is given in Table5.4 for crusher operation in open-circuit and closed-circuit situations.
The Standard cone crushers are for normal use. The Short Head cone crushers are designed for tertiary or quaternary crushing where finer product is required. These crushers are invariably operated in closed circuit. The final product sizes are fine, medium or coarse depending on the closed set spacing, the configuration of the crushing chamber and classifier performance, which is always installed in parallel.
For finer product sizes, i.e., less than 6mm, special cone crushers known as Gyradisc crushers are available. The operation is similar to the standard cone crushers, except that the size reduction is caused more by attrition than by impact . The reduction ratio is around 8:1 and as the product size is relatively small the feed size is limited to less than 50mm with a nip angle between 25 and 30. The Gyradisc crushers have head diameters from around 900 to 2100mm. These crushers are always operated under choke feed conditions. The feed size is less than 50mm and therefore the product size is usually less than 69mm.
Maintenance of the wear components in both gyratory and cone crushers is one of the major operating costs. Wear monitoring is possible using a Faro Arm (Figure 6.10), which is a portable coordinate measurement machine. Ultrasonic profiling is also used. A more advanced system using a laser scanner tool to profile the mantle and concave produces a 3D image of the crushing chamber (Erikson, 2014). Some of the benefits of the liner profiling systems include: improved prediction of mantle and concave liner replacement; identifying asymmetric and high wear areas; measurement of open and closed side settings; and quantifying wear life with competing liner alloys.
Various types of rock fracture occur at different loading rates. For example, rock destruction by a boring machine, a jaw or cone crusher, and a grinding roll machine are within the extent of low loading rates, often called quasistatic loading condition. On the contrary, rock fracture in percussive drilling and blasting happens under high loading rates, usually named dynamic loading condition. This chapter presents loading rate effects on rock strengths, rock fracture toughness, rock fragmentation, energy partitioning, and energy efficiency. Finally, some of engineering applications of loading rate effects are discussed.
In Chapter4, we have already seen the mechanism of crushing in a jaw crusher. Considering it further we can see that when a single particle, marked 1 in Figure11.5a, is nipped between the jaws of a jaw crusher the particle breaks producing fragments, marked 2 and 3 in Figure11.5b. Particles marked 2 are larger than the open set on the crusher and are retained for crushing on the next cycle. Particles of size 3, smaller than the open set of the crusher, can travel down faster and occupy or pass through the lower portion of the crusher while the jaw swings away. In the next cycle the probability of the larger particles (size 2) breaking is greater than the smaller sized particle 3. In the following cycle, therefore, particle size 2 is likely to disappear preferentially and the progeny joins the rest of thesmaller size particles indicated as 3 in Figure11.5c. In the figures, the position of the crushed particles that do not exist after comminution is shaded white (merely to indicate the positions they had occupied before comminution). Particles that have been crushed and travelled down are shown in grey. The figure clearly illustrates the mechanism of crushing and the classification that takes place within the breaking zone during the process, as also illustrated in Figure11.4. This type of breakage process occurs within a jaw crusher, gyratory crusher, roll crusher and rod mills. Equation (11.19) then is a description of the crusher model.
In practice however, instead of a single particle, the feed consists of a combination of particles present in several size fractions. The probability of breakage of some relatively larger sized particles in preference to smaller particles has already been mentioned. For completeness, the curve for the probability of breakage of different particle sizes is again shown in Figure11.6. It can be seen that for particle sizes ranging between 0 K1, the probability of breakage is zero as the particles are too small. Sizes between K1 and K2 are assumed to break according a parabolic curve. Particle sizes greater than K2 would always be broken. According to Whiten , this classification function Ci, representing the probability of a particle of size di entering the breakage stage of the crusher, may be expressed as
The classification function can be readily expressed as a lower triangular matrix [1,16] where the elements represent the proportion of particles in each size interval that would break. To construct a mathematical model to relate product and feed sizes where the crusher feed contains a proportion of particles which are smaller than the closed set and hence will pass through the crusher with little or no breakage, Whiten  advocated a crusher model as shown in Figure11.7.
The considerations in Figure11.7 are similar to the general model for size reduction illustrated in Figure11.4 except in this case the feed is initially directed to a classifier, which eliminates particle sizes less than K1. The coarse classifier product then enters the crushing zone. Thus, only the crushable larger size material enters the crusher zone. The crusher product iscombined with the main feed and the process repeated. The undersize from the classifier is the product.
While considering the above aspects of a model of crushers, it is important to remember that the size reduction process in commercial operations is continuous over long periods of time. In actual practice, therefore, the same operation is repeated over long periods, so the general expression for product size must take this factor into account. Hence, a parameter v is introduced to represent the number of cycles of operation. As all cycles are assumed identical the general model given in Equation (11.31) should, therefore, be modified as
Multiple vectors B C written in matrix form:BC=0.580000.200.60000.120.180.6100.040.090.20.571.000000.700000.4500000=0581+00+00+000.580+00.7+00+000580+00+00.45+000.580+00+00+000.21+0.60+00+000.20+0.60.7+00+000.20+0.60+00.45+000.20+0.60+00+000.121+0.180+0.610+000.120+0.180.7+0.610+000.120+0.180+0.610.45+000.120+0.180+0.610+000.041+0.090+0.20+0.5700.040+0.090.7+0.20+0.5700.040+0.090+0.20.45+0.5700.040+0.090+0.20+0.570=0.580000.20.42000.120.1260.274500.040.0630.090
Now determine (I B C) and (I C)(IBC)=10.5800000000.210.42000000.1200.12610.27450000.0400.06300.0910=0.420000.20.58000.120.1260.725500.040.0630.091and(IC)=000000.300000.5500001
Now find the values of x1, x2, x3 and x4 as(0.42x1)+(0x2)+(0x3)+(0x4)=10,thereforex1=23.8(0.2x1)+(0.58x2)+(0x3)+(0x4)=33,thereforex2=65.1(0.12x1)+(0.126x2)+(0.7255x3)+(0x4)=32,thereforex3=59.4(0.04x1)+(0.063x2)+(0.09x3)+(1x4)=20,thereforex4=30.4
In this process, mined quartz is crushed into pieces using crushing/smashing equipment. Generally, the quartz smashing plant comprises a jaw smasher, a cone crusher, an impact smasher, a vibrating feeder, a vibrating screen, and a belt conveyor. The vibrating feeder feeds materials to the jaw crusher for essential crushing. At that point, the yielding material from the jaw crusher is moved to a cone crusher for optional crushing, and afterward to effect for the third time crushing. As part of next process, the squashed quartz is moved to a vibrating screen for sieving to various sizes.
Crushers are widely used as a primary stage to produce the particulate product finer than about 50100mm. They are classified as jaw, gyratory, and cone crushers based on compression, cutter mill based on shear, and hammer crusher based on impact.
A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake. A Fritsch jaw crusher with maximal feed size 95mm, final fineness (depends on gap setting) 0.315mm, and maximal continuous throughput 250Kg/h is shown in Fig. 2.8.
A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.
Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing hard metal scrap for different hard metal recycling processes. Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor. Crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough to pass through the openings of the grating or screen. The size of the product can be regulated by changing the spacing of the grate bars or the opening of the screen.
The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure, forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions. A design for a hammer crusher (Fig. 2.9) essentially allows a decrease of the elevated pressure of air in the crusher discharging unit . The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, the circulation of suspended matter in the gas between A and B zones is established and the high pressure of air in the discharging unit of crusher is reduced.
Crushers are widely used as a primary stage to produce the particulate product finer than about 50100 mm in size. They are classified as jaw, gyratory and cone crushers based on compression, cutter mill based on shear and hammer crusher based on impact.
A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake.
A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.
Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing of hard metal scrap for different hard metal recycling processes.
Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor and crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough pass through the openings of the grating or screen. The size of product can be regulated by changing the spacing of the grate bars or the opening of the screen.
The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around of the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions.
A design for a hammer crusher (Figure 2.6) allows essentially a decrease of the elevated pressure of air in the crusher discharging unit . The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, circulation of suspended matter in the gas between A- and B-zones is established and high pressure of air in the discharging unit of crusher is reduced.
For a particular operation where the ore size is known, it is necessary to estimate the diameter of rolls required for a specific degree of size reduction. To estimate the roll diameter, it is convenient to assume that the particle to be crushed is spherical and roll surfaces are smooth. Figure6.2 shows a spherical particle about to enter the crushing zone of a roll crusher and is about to be nipped. For rolls that have equal radius and length, tangents drawn at the point of contact of the particle and the two rolls meet to form the nip angle (2). From simple geometry it can be seen that for a particle of size d, nipped between two rolls of radius R:
Equation (6.2) indicates that to estimate the radius R of the roll, the nip angle is required. The nip angle on its part will depend on the coefficient of friction, , between the roll surface and the particle surface. To estimate the coefficient of friction, consider a compressive force, F, exerted by the rolls on the particle just prior to crushing, operating normal to the roll surface, at the point of contact, and the frictional force between the roll and particle acting along a tangent to the roll surface at the point of contact. The frictional force is a function of the compressive force F and is given by the expression, F. If we consider the vertical components of these forces, and neglect the force due to gravity, then it can be seen that at the point of contact (Figure6.2) for the particle to be just nipped by the rolls, the equilibrium conditions apply where
As the friction coefficient is roughly between 0.20 and 0.30, the nip angle has a value of about 1117. However, when the rolls are in motion the friction characteristics between the ore particle will depend on the speed of the rolls. According to Wills , the speed is related to the kinetic coefficient of friction of the revolving rolls, K, by the relation
Equation (6.4) shows that the K values decrease slightly with increasing speed. For speed changes between 150 and 200rpm and ranging from 0.2 to 0.3, the value of K changes between 0.037 and 0.056. Equation (6.2) can be used to select the size of roll crushers for specific requirements. For nip angles between 11 and 17, Figure6.3 indicates the roll sizes calculated for different maximum feed sizes for a set of 12.5mm.
The maximum particle size of a limestone sample received from a cone crusher was 2.5cm. It was required to further crush it down to 0.5cm in a roll crusher with smooth rolls. The friction coefficient between steel and particles was 0.25, if the rolls were set at 6.3mm and both revolved to crush, estimate the diameter of the rolls.
It is generally observed that rolls can accept particles sizes larger than the calculated diameters and larger nip angles when the rate of entry of feed in crushing zone is comparable with the speed of rotation of the rolls.
Jaw crushers are mainly used as primary crushers to produce material that can be transported by belt conveyors to the next crushing stages. The crushing process takes place between a fixed jaw and a moving jaw. The moving jaw dies are mounted on a pitman that has a reciprocating motion. The jaw dies must be replaced regularly due to wear. Figure 8.1 shows two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is installed on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action of the moving jaw. A double toggle crusher has, basically, two shafts and two toggle plates. The first shaft is a pivoting shaft on the top of the crusher, while the other is an eccentric shaft that drives both toggle plates. The moving jaw has a pure reciprocating motion toward the fixed jaw. The crushing force is doubled compared to single toggle crushers and it can crush very hard ores. The jaw crusher is reliable and robust and therefore quite popular in primary crushing plants. The capacity of jaw crushers is limited, so they are typically used for small or medium projects up to approximately 1600t/h. Vibrating screens are often placed ahead of the jaw crushers to remove undersize material, or scalp the feed, and thereby increase the capacity of the primary crushing operation.
Both cone and gyratory crushers, as shown in Figure 8.2, have an oscillating shaft. The material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly. An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between the open side setting (o.s.s.) and closed side setting (c.s.s.). In addition to c.s.s., eccentricity is one of the major factors that determine the capacity of gyratory and cone crushers. The fragmentation of the material results from the continuous compression that takes place between the mantle and bowl liners. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is also called interparticle crushing. The gyratory crushers are equipped with a hydraulic setting adjustment system, which adjusts c.s.s. and thus affects product size distribution. Depending on cone type, the c.s.s. setting can be adjusted in two ways. The first way is by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that the liners wear more evenly. Another principle of setting adjustment is by lifting/lowering the main shaft. An advantage of this is that adjustment can be done continuously under load. To optimize operating costs and improve the product shape, as a rule of thumb, it is recommended that cones always be choke-fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices that detect the maximum and minimum levels of the material are used to start and stop the feed of material to the crusher as needed.
Primary gyratory crushers are used in the primary crushing stage. Compared to the cone type crusher, a gyratory crusher has a crushing chamber designed to accept feed material of a relatively large size in relation to the mantle diameter. The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has capacities starting from 1200 to above 5000t/h. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Therefore, primary gyratories require quite a massive foundation.
The cone crusher is a modified gyratory crusher. The essential difference is that the shorter spindle of the cone crusher is not suspended, as in the gyratory, but is supported in a curved, universal bearing below the gyratory head or cone (Figure 8.2). Power is transmitted from the source to the countershaft to a V-belt or direct drive. The countershaft has a bevel pinion pressed and keyed to it and drives the gear on the eccentric assembly. The eccentric assembly has a tapered, offset bore and provides the means whereby the head and main shaft follow an eccentric path during each cycle of rotation. Cone crushers are used for intermediate and fine crushing after primary crushing. The key factor for the performance of a cone type secondary crusher is the profile of the crushing chamber or cavity. Therefore, there is normally a range of standard cavities available for each crusher, to allow selection of the appropriate cavity for the feed material in question.
The main task of renovation construction waste handling is the separation of lightweight impurities and construction waste. The rolling crusher with opposite rollers is capable of crushing the brittle debris and compressing the lightweight materials by the low-speed and high-pressure extrusion of the two opposite rollers. As the gap between the opposite rollers, rotation speed, and pressure are all adjustable, materials of different scales in renovation construction waste can be handled.
The concrete C&D waste recycling process of impact crusher+cone crusher+hoop-roller grinder is also capable of handling brick waste. In general, the secondary crushing using the cone crusher in this process with an enclosed crusher is a process of multicrushing, and the water content of waste will become an important affecting factor. The wet waste will be adhered on the wall of the grinding chamber, and the crushing efficiency and waste discharging will be affected. When the climate is humid, only coarse impact crushing is performed and in this case the crushed materials are used for roadbase materials. Otherwise, three consecutive crushings are performed and the recycled coarse aggregate, fine aggregate, and powder materials are collected, respectively.
The brick and concrete C&D waste recycling process of impact crusher+rolling crusher+hoop-roller grinder is also capable of handling the concrete waste. In this case, the water content of waste will not be an important affecting factor. This process is suitable in the regions with wet climates.
The renovation C&D waste recycling process of rolling crusher (coarse/primary crushing)+rolling crusher (intermediate/secondary crushing)+rolling crusher (fine/tertiary crushing) is also capable of handling the two kinds of waste discussed earlier. The particle size of debris is crushed less than 20mm and the lightweight materials are compressed, and they are separated using the drum sieve. The energy consumption is low in this process; however, the shape of products is not good (usually flat and with cracks). There is no problem in roadbase material and raw materials of prefabricated product production. But molders (the rotation of rotors in crusher is used to polish the edge and corner) should be used for premixed concrete and mortar production.