jaw crusher is a classification of

types of crushers

types of crushers

Impact Crushers: This division is represented chiefly by the various styles of hammermill; also by the cage type disintegrator. Combination Impact and Sledging Crushers. In this class we have the single or double sledging roll crushers. An example of the former is the Fairmount crusher, of the latter, the Edison roll crusher.

Some further subdividing and qualification might be applied to these general classifications, but these, for the most part, are not of particular importance. Pressure crushers, for example, may be divided into two subclasses: the reciprocating, and the continuous-pressure, types. The gyratory and jaw crushers come under the first category, the crushing rolls under the second. Strictly speaking, the gyratory motion is not a reciprocating one, but it is so with respect to any vertical radial plane through the crushing chamber; therefore it is convenient to view it in that light. Some roll crushers, notably the light coal crushing type, have more of a tearing action, as contrasted to the heavy sledging performance of such machines as the Fairmount crusher.

During the same years wherein the industry was concerned with development of larger and still larger primary crushers,another member of the family was born: the single, sledging- roll crusher. The Allis-Chalmers Co. entered this field in 1911, building two sets of 36 dia. x 60 face single-roll crushers, flux limestone plant. Taking the name of its proving ground, this machine was christened the Fairmount crusher. The machine quickly achieved a high degree of popularity, and although its field of application is relatively limited, quite a number of them were in-stalled for primary crushing service. The line was expanded to include smaller sizes, as well as the big 60- x 84-in. machine.

Development of concentration and cyanidation in the mining industry called for finer crushing than was feasible in the gyratory or jaw crushers then available. This requirement was met for a number of years by the double smooth-face crushing rolls, originally known as Cornish rolls. As the mining industry during the period we are discussing was a very active one, the development in this type of crusher had reached a fairly high stage before the end of the century, and some excellent heavy-duty roils were available at that time. That this machine was not used to any considerable extent in the commercial crushing plants of that period was due simply to the fact that there was no demand for the smaller sizes of crushed stone, at least not any more than could be taken care of by the crushing methods then in vogue in such plants. This brings us to the rather significant fact that, while all of the interesting and rather remarkable development we have outlined was going on, very little, if anything, was being done to develop special crushers for secondary and fine-reduction work, other than the work on crushing rolls just described.

a jaw, b cone, c mushroom, d hammer, e roller; 1 fixed cheek with the rotation axis; 2 a movable cheek; 3, 4 the eccentric shaft; 5 rod; 6 hinged rear bearing spacer cheeks; 7 spring; 8, 9 width adjustment mechanism of the discharge gap; 10 pull the lock device; 11 bed; 12 still cone; 13 cone moving; 14 traverse; 15 hinge suspension rolling cone; 16 cone of the shaft; 17 drive shaft; 18 eccentric; 19 amortization spring; 20 foot ring ;21 regulating ring; 22 thrust bearing cone; 23 rotor; 24 liner plates; 25 grate; 26 hammer; 27 main frame; 28 crushing rolls.

what is a jaw crusher | advantages, types, parts and specifications | quarrying & aggregates

what is a jaw crusher | advantages, types, parts and specifications | quarrying & aggregates

The series of jaw crushers produced by Rayco are widely used in mining and aggregate crushing industries. They are specially developed for crushing the hardest ores and rocks, and are mainly used as primary crushers.

When working, the motor drives the belt and pulley to move the movable jaw up and down through the eccentric shaft. When the movable jaw rises, the angle between the toggle plate and the movable jaw becomes larger, thereby pushing the movable jaw plate closer to the fixed jaw plate, and the material passes through the two jaws. The squeezing and rolling between the plates realize multiple crushing.

When the movable jaw descends, the angle between the toggle plate and the movable jaw becomes smaller. The movable jaw plate leaves the fixed jaw plate under the action of the pull rod and the spring, and the crushed material passes through the discharge port in the lower jaw cavity freely under the action of gravity Unload.

When crushing high hardness and strong corrosive materials, C6X can accomplish the task very well. Its equipment structure, manufacturing technology and material selection determine the high strength of its body. Not only can it be used for coarse crushing of the hardest rocks and ore, but also can be continuously produced in the most demanding production environment on the ground and underground to ensure the maximum production efficiency of customers.

jaw crusher explained - savree

jaw crusher explained - savree

Comminutionis the process by which minedoreis reduced in size to make for easier processing. The strict definition is the action of taking a material, specifically mineral ore, and reducing it to minute fragments or particles. This is typically achieved in several stages of a detailed and professionalminingoperation.

Some of the earliest versions ofcrusherswere large stones used by humans to repeatedly hammer rocks placed upon an anvil (a hard stationary surface); the products made from this hammering action were transported by pack animals or humans in sacks. Historically, mining tasks were incredibly labour intensive, and the produced mined products were correspondingly expensive. The only tools available to breakdown ore were adrill bit,sledgehammer, or apickaxe(and the will power of a few tireless workers). The majority of ore sizing and crushing operations were completed by hand until halfway through the 19thcentury. At this time,water powered trip hammersstarted assisting miners; it was roughly the beginning of theindustrial revolution.

During the industrial revolution, commercial mining started seeing the use ofexplosivessuch asgunpowderat the heart of many mining operations; this mining method is known as blasting and it led to ever larger quantities ofrockandmineralsbeing liberated.Steam shovelswere the next tool to revolutionise the mining industry. Over time,larger machinesand moreadvanced mining techniquesstarted making it possible to liberate significantly larger pieces of ore.

The demand for mined minerals and other mined by-products has not reduced over the past 150 years. To ensure supply could meet demand, many differentcrushingandconveyingmachines were invented. Without simultaneous advances within the fields of comminution and conveying, it would not have been possible to mine and convey materials safely and efficiently (even modern conveyors cannot convey single blocks of material weighing many tonnes).

Almost all quarry and mining operations today make use of crushers to reduce the size of larger materials; loose (smaller) sized materials do not typically require a crushing stage. When mining harder rock,jaw crushers,cone crushers, and/orgyratory crushersare usually employed.

Acrusheris a machine designed to reduce the size of large rocks tosmaller rocks,gravel,sand,orrock dust; this is essential for efficient transport of the product via conveyors etc. Crushing is the first of many stages that lead to separation of themineral(s)from thewaste(gangue) material. Waste material can be discarded or recycled allowing the mineral rich product to be further processed at the main plant.

Various types ofcrusherandmineral separatormay be employed depending upon thethroughput,hardness, andpropertiesof the mineral being processed. In all cases, the crushing stage is essentially achieved by transferring a mechanically amplified force (viamechanical advantage)to a material, to breakdown the bonds which hold the material together.

Crushingis achieved by passing the feed between two solid surfaces, then by applying sufficient force to bring the surfaces together so that the molecules of the material being crushed areseparatedfrom (fracture), or,change alignmentin relation to (deform), each other.

Crushers are commonly classified by the degree to which they fragment the starting material, withprimaryandsecondarycrushers handlingcoarse materials, andtertiaryandquaternary crushersreducing particles tofinergradations. Each crusher is designed to work with a certain maximum size of raw material, and often delivers its output to ascreening machine(screener) which sorts and directs the product for further processing. In many cases, initial crushing stages are followed by further milling stages (if the materials need to be further reduced); see ourball millarticle for further details.

Typically, the initial crushing stage is completed using eithergyratory crushersorjaw crushers. It is often the case that there will be only one crusher installed, and this will be referred to as the primary crusher.

The Blake crusher was first patented byEli Whitney Blakein1858and it is the most common type of jaw crusher employed today. The Blake type jaw crusher has afixed feedarea and avariable dischargearea. Blake type crushers come invarious sizesand are commonly used forprimaryandsecondarycrushing roles.

Jaw crushers aresizedbased upon the dimensions of the top feed inlet (gape) or the dimensions of the jaws. For example, a 32 x 54 sized jaw crusher will measure 32 inches from the movable to stationary jaw (when measured at the top i.e. the opening), and each jaw will have a 54-inch width. If a jaw crusher is rated by jaw plate size, a suitable rating maybe 600 x 400, which indicates a 600 mm by 400 mm jaw plate dimension. Sizes may be given inimperial(inches etc.) ormetric(millimetre etc.).

Material is fed into the top feed opening (gape) and gradually moves downwards towards the lower discharge outlet. As the materials passes towards the outlet, it is crushed between the stationary and moving jaws. Thev-shaped areabetween the two jaws is referred to as the crushing chamber. Because the space between the two jaws becomes narrower towards the discharge outlet, the material size is progressively reduced.

Thegapbetween the jaws at the discharge outlet dictates the material output size. A typical jaw crusher will have a crushing ratio of between6:1to8:1i.e. the feed material size is reduced by a factor of 6 or 8.

crushers - an overview | sciencedirect topics

crushers - an overview | sciencedirect topics

This crusher developed by Jaques (now Terex Mineral Processing Solutions) has several internal chamber configurations available depending on the abrasiveness of the ore. Examples include the Rock on Rock, Rock on Anvil and Shoe and Anvil configurations (Figure 6.26). These units typically operate with 5 to 6 steel impellers or hammers, with a ring of thin anvils. Rock is hit or accelerated to impact on the anvils, after which the broken fragments freefall into the discharge chute and onto a product conveyor belt. This impact size reduction process was modeled by Kojovic (1996) and Djordjevic et al. (2003) using rotor dimensions and speed, and rock breakage characteristics measured in the laboratory. The model was also extended to the Barmac crushers (Napier-Munn et al., 1996).

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 [5]. 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.

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 [5]. 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.

Secondary coal crusher: Used when the coal coming from the supplier is large enough to be handled by a single crusher. The primary crusher converts the feed size to one that is acceptable to the secondary crusher.

The main sources of RA are either from construction and ready mixed concrete sites, demolition sites or from roads. The demolition sites produce a heterogeneous material, whereas ready mixed concrete or prefabricated concrete plants produce a more homogeneous material. RAs are mainly produced in fixed crushing plant around big cities where CDWs are available. However, for roads and to reduce transportation cost, mobile crushing installations are used.

The materiel for RA manufacturing does not differ from that of producing NA in quarries. However, it should be more robust to resist wear, and it handles large blocks of up to 1m. The main difference is that RAs need the elimination of contaminants such as wood, joint sealants, plastics, and steel which should be removed with blast of air for light materials and electro-magnets for steel. The materials are first separated from other undesired materials then treated by washing and air to take out contamination. The quality and grading of aggregates depend on the choice of the crusher type.

Jaw crusher: The material is crushed between a fixed jaw and a mobile jaw. The feed is subjected to repeated pressure as it passes downwards and is progressively reduced in size until it is small enough to pass out of the crushing chamber. This crusher produces less fines but the aggregates have a more elongated form.

Hammer (impact) crusher: The feed is fragmented by kinetic energy introduced by a rotating mass (the rotor) which projects the material against a fixed surface causing it to shatter causing further particle size reduction. This crusher produces more rounded shape.

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.

Roll crushers are arbitrarily divided into light and heavy duty crushers. The diameters of the light duty crushers vary between 228 and 760mm with face lengths between 250 and 460mm. The spring pressure for light duty rolls varies between 1.1 and 5.6kg/m. The heavy duty crusher diameters range between 900 and 1000mm with face length between 300 and 610mm. In general, the spring pressures of the heavy duty rolls range between 7 and 60kg/m. The light duty rolls are designed to operate at faster speeds compared to heavy duty rolls that are designed to operate at lower speeds.

It has been stressed that the coal supplier should initially crush the materials to a maximum size such as 300 mm, but they may be something else depending on the agreement or coal tie up. To circumvent the situation, the CHP keeps a crushing provision so that coal bunkers receive the materials at a maximum size of about 2025 mm.

The unloaded coal in the hoppers is transferred to the crusher house through belt conveyors with different stopovers in between such as the penthouse, transfer points, etc., depending on the CHP layout.

Suspended magnets for the removal of tramp iron pieces and metal detectors for identifying nonferrous materials are provided at strategic points to intercept unacceptable materials before they reach the crushers. There may be arrangements for manual stone picking from the conveyors, as suitable. Crushed coal is then sent directly to the stockyard.

A coal-sampling unit is provided for uncrushed coal. Online coal analyzers are also available, but they are a costly item. Screens (vibrating grizzly or rollers) are provided at the upstream of the crushers to sort out the smaller sizes as stipulated, and larger pieces are guided to the crushers.

Appropriate types of isolation gates, for example, rod or rack and pinion gates, are provided before screens to isolate one set of crushers/screens to carry on maintenance work without affecting the operation of other streams.

Vibrating grizzly or roller screens are provided upstream of the crushers for less than 25 (typical) mm coal particles bypass the crusher and coal size more than 25 mm then fed to the crushers. The crushed coal is either fed to the coal bunkers of the boilers or discharged to the coal stockyard through conveyors and transfer points, if any.

This is used for crushing and breaking large coal in the first step of coal crushing plant applied most widely in coal crushing industry. Jaw crushers are designed for primary crushing of hard rocks without rubbing and with minimum dust. Jaw crushers may be utilized for materials such as coal, granite, basalt, river gravel, bauxite, marble, slag, hard rock, limestone, iron ore, magazine ore, etc., within a pressure resistance strength of 200 MPa. Jaw crushers are characterized for different features such as a simple structure, easy maintenance, low cost, high crushing ratio, and high resistance to friction/abrasion/compression with a longer operating lifespan.

Fixed and movable jaw plates are the two main components. A motor-driven eccentric shaft through suitable hardware makes the movable jaw plate travel in a regulated track and hit the materials in the crushing chamber comprising a fixed-jaw plate to assert compression force for crushing.

A coal hammer crusher is developed for materials having pressure-resistance strength over 100 Mpa and humidity not more than 15%. A hammer crusher is suitable for mid-hard and light erosive materials such as coal, salt, chalk, gypsum, limestone, etc.

Hammer mills are primarily steel drums that contain a vertical or horizontal cross-shaped rotor mounted with pivoting hammers that can freely swing on either end of the cross. While the material is fed into the feed hopper, the rotor placed inside the drum is spun at a high speed. Thereafter, the hammers on the ends of the rotating cross thrust the material, thereby shredding and expelling it through the screens fitted in the drum.

Ring granulators are used for crushing coal to a size acceptable to the mills for conversion to powdered coal. A ring granulator prevents both the oversizing and undersizing of coal, helping the quality of the finished product and improving the workability. Due to its strong construction, a ring granulator is capable of crushing coal, limestone, lignite, or gypsum as well as other medium-to-hard friable items. Ring granulators are rugged, dependable, and specially designed for continuous high capacity crushing of materials. Ring granulators are available with operating capacities from 40 to 1800 tons/h or even more with a feed size up to 500 mm. Adjustment of clearance between the cage and the path of the rings takes care of the product gradation as well as compensates for wear and tear of the machine parts for maintaining product size. The unique combination of impact and rolling compression makes the crushing action yield a higher output with a lower noise level and power consumption. Here, the product is almost of uniform granular size with n adjustable range of less than 2025 mm. As the crushing action involves minimum attrition, thereby minimum fines are produced with improving efficiency.

A ring granulator works on n operating principle similar to a hammer mill, but the hammers are replaced with rolling rings. The ring granulator compresses material by impact in association with shear and compression force. It comprises a screen plate/cage bar steel box with an opening in the top cover for feeding. The power-driven horizontal main shaft passes from frame side to frame side, supporting a number of circular discs fixed at regular intervals across its length within the frame. There are quite a few bars running parallel to the main shaft and around the periphery that pass through these discs near their outer edges. The bars are uniformly located about the center of the main rotating shaft. There are a series of rings in between the two consecutive disc spaces, mounted on each bar. They are free to rotate on the bars irrespective of the main shaft rotation. The entire cage assembly, located below the rotor assembly, can be set at a desired close proximity to the rings by screw jack mechanism adjustable from outside the crusher frame. The rotor assembly consisting of the shaft, discs, rings, etc., is fixed as far as the main shaft center line is concerned. This main shaft carries in roller bearings from the box sides. The movable cage frame arrangement is provided so as to set its inner radius marginally larger than that of the ring running periphery. When coal is fed from the top, the rings also rotate along with the shaft and around their own center line along the bars, which drags coal lumps and crushes them to the desired size. After the coal has been crushed by the coal crusher, a vibrating screen grades the coal by size and the coal is then transported via belt conveyor. In this process, a dewatering screen is optional to remove water from the product.

Crusher machines are used for crushing of a wide variety of materials in the mining, iron and steel, and quarry industries. In quarry industry, they are used for crushing of rocks into granites for road-building and civil works. Crusher machines are equipped with a pair of crusher jaws namely; fixed jaws and swing jaws. Both jaws are fixed in a vertical position at the front end of a hollow rectangular frame of crushing machine as shown in Fig.10.1. The swing jaw is moved against the fixed jaws through knuckle action by the rising and falling of a second lever (pitman) carried by eccentric shaft. The vertical movement is then horizontally fixed to the jaw by double toggle plates. Because the jaw is pivoted at the top, the throw is greatest at the discharge, preventing chocking.

The crushing force is produced by an eccentric shaft. Then it is transferred to the crushing zone via a toggle plate system and supported by the back wall of the housing of the machine. Spring-pulling rods keep the whole system in a condition of no positive connection. Centrifugal masses on the eccentric shaft serve as compensation for heavy loads. A flywheel is provided in the form of a pulley. Due to the favorable angle of dip between the crushing jaws, the feeding material can be reduced directly after entering the machine. The final grain size distribution is influenced by both the adjustable crusher setting and the suitability of the tooth form selected for the crushing plates.

Thus, the crusher jaws must be hard and tough enough to crush rock and meet the impact action generated by the action of swing jaws respectively. If the jaws are hard, it will be efficient in crushing rock but it will be susceptible to fracture failure. On the other hand, if the jaws are tough, the teeth will worn out very fast, but it will be able to withstand fracture failure. Thus, crusher jaws are made of highly wear-resistant austenitic manganese steel casting, which combines both high toughness and good resistance to wear.

Austenitic manganese steel was invented by Sir Robert Hadfield in 1882 and was first granted patented in Britain in 1883 with patent number 200. The first United States patents, numbers 303150 and 303151, were granted in 1884. In accordance with ASTM A128 specification, the basic chemical composition of Hadfield steel is 1%1.4% carbon and 11%14% manganese. However, the manganese to carbon ratio is optimum at 10:1 to ensure an austenitic microstructure after quenching [2]. Austenitic manganese steels possess unique resistance to impact and abrasion wears. They exhibit high levels of ductility and toughness, slow crack propagation rates, and a high rate of work-hardening resulting in superior wear resistance in comparison with other potentially competitive materials [310]. These unique properties have made Hadfield's austenitic manganese steel an engineering material of choice for use in heavy industries, such as earth moving, mining, quarrying, oil and gas drilling, and in processing of various materials for components of crushers, mills, and construction machinery (lining plates, hammers, jaws, cones).

Austenitic manganese steel has a yield strength between 50,000psi (345MPa) and 60,000psi (414MPa) [3]. Although stronger than low carbon steel, it is not as strong as medium carbon steel. It is, however, much tougher than medium carbon steel. Yielding in austenitic manganese steel signifies the onset of work-hardening and accompanying plastic deformation. The modulus of elasticity for austenitic manganese steel is 27106psi (186103MPa) and is somewhat below that of carbon steel, which is generally taken as 29106psi (200103MPa). The ultimate tensile strength of austenitic manganese steel varies but is generally taken as 140,000psi (965MPa). At this tensile strength, austenitic manganese steel displays elongation in the 35%40% range. The fatigue limit for manganese steel is about 39,000psi (269MPa). The ability of austenitic manganese to work-harden up to its ultimate tensile strength is its main feature. In this regard austenitic manganese has no equal. The range of work-hardening of austenitic manganese from yield to ultimate tensile is approximately 200%.

When subjected to impact loads Hadfield steel work-hardens considerably while exhibiting superior toughness. However, due to its low yield strength, large deformation may occur and lead to failure before the work-hardening sets in [11]. This phenomenon is detrimental when it comes to some applications, such as rock crushing [12]. Work-hardening behavior of Hadfield steel has been attributed to dynamic strain aging [13]. The hardening or strengthening mechanism has its origin in the interactions between dislocations and the high concentration of interstitial atoms also known as the CottrellBilby interaction. Thus, the wear properties of Hadfield steel are related to its microstructure, which in turn is dependent on the heat-treatment process and chemical composition of the alloy. According to Haakonsen [14], work-hardening is influenced by such parameters as alloy chemistry, temperature, and strain rate.

Carbon content affects the yield strength of AMS. Carbon levels below 1% cause yield strengths to decrease. The optimum carbon content has been found to be between 1% and 1.2%. Above 1.2% carbides precipitate and segregate to grain boundaries, resulting in compromised strength and ductility particularly in heavy sections [15]. Other alloying elements, such as chromium, will increase the yield strength, but decrease ductility. Silicon is generally added as a deoxidizer. Carbon contents above 1.4% are not generally used as the carbon segregates to the grain boundaries as carbides and is detrimental to both strength and ductility [15].

Manganese has very little effect on the yield strength of austenitic manganese steel, but does affect both the ultimate tensile strength and ductility. Maximum tensile strengths are attained with 12%13% manganese contents [16]. Although acceptable mechanical properties can be achieved up to 20% manganese content, there is no economic advantage in using manganese contents greater than 13%. Manganese acts as an austenitic stabilizer and delays isothermal transformation. For example, carbon steel containing 1% manganese begins isothermal transformation about 15s after quenching to 371C, whereas steel containing 12% manganese begins isothermal transformation about 48h after quenching to 371C [15].

Austenitic manganese steel in as-cast condition is characterized by an austenitic microstructure with precipitates of alloyed cementite and the triple phosphorus eutectic of an Fe-(Fe,Mn)3C-(Fe,Mn)3P type [17], which appears when the phosphorus content exceeds 0.04% [18]. It also contains nonmetallic inclusions, such as oxides, sulfides, and nitrides. This type of microstructure is unfavorable due to the presence of the (Fe, Mn)xCy carbides spread along the grain boundaries [19]. However, in solution-treated conditions austenitic manganese steel structure is essentially austenitic because carbon is in austenite solution [19]. The practical limit of carbon in solution is about 1.2%. Thereafter, excess carbon precipitation to the grain boundaries results, especially in heavier sections [20].

Austenitic manganese steel in the as-cast condition is too brittle for normal use. As section thickness increases, the cooling rate within the molds decreases. This decreased cooling rate results in increased embrittlement due to carbon precipitation. In as-cast castings, the tensile strength ranges from approximately 50,000psi. (345MPa) to 70,000psi (483MPa) and displays elongation values below 1%. Heat treatment is used to strengthen and increase the mechanical properties of austenitic manganese steel. The normal heat-treatment method consists of solution annealing and rapid quenching in a water bath.

Considering the mechanical properties, it is difficult to imagine that a casting made from Hadfield steel could suffer failure in service. However, cases like this do happen, especially in heavy-section elements and result in enormous losses of material and long downtimes. The reason for such failures is usually attributed to insufficient ductility, resulting from sensitivity of austenitic manganese steel to section size, heat treatment, and the rapidity and effectiveness of quenching [21]. Poor quench compounded by large section size results in an unstable, in-homogenous structure, subject to transformation to martensite under increased loading and strain rate. This article investigates the cause of incessant failure of locally produced crusher jaws from Hadfield steel.

According to the recent marketing research data conducted by the foundry an estimate of 15,000metrictons of this component is being consumed annually in the local market. This is valued at about $30million. From this market demand, the foundry plant can only supply about 5% valued at $1.5million. This is because the crusher jaws produced locally failed prematurely. Hence, this study aimed at investigating the causes of failure.

Annual wine exports in the European Union is around 21.9 billion (Eurostat) with France being the main wine exporting country followed by Italy and Spain. The wine production process (Fig. 9.1) can be divided into the following stages (Sections 9.2.1.19.2.1.4).

Grape crushers or crusher destemmers are initially used via light processing to avoid seed fracture. Sulfur dioxide is added to the mass to prevent oxidation. At this stage, grape stems are produced as one of the waste streams of the winery process. The mash is pressed in continuous, pneumatic, or vertical basket presses leading to the separation of the pomace (marc) from the must. Microbial growth is suppressed via sulfur dioxide addition.

The solids present in the must are removed before or after fermentation for white wine production. Fining is achieved by combined processes including filtration, centrifugation, flocculation, physicochemical treatment (e.g., activated carbon, gelatin, etc.,), and stabilization to prevent turbidity formation (e.g., the use of bentonite, cold stabilization techniques, etc.). Clarification leads to the separation of sediments via racking.

Wine production is carried out at temperatures lower than 20C for 610 weeks in stainless steel bioreactors or vats with or without yeast inoculation (most frequently Saccharomyces cerevisiae). At the end of fermentation, the wine is cooled (4C5C) and subsequently aged in barrels or wooden vats. The sediment that is produced during fermentation and aging is called wine lees and constitutes one of the waste streams produced by wineries. Current uses of wine lees include tartrate production and ethanol distillation. Lees could also be processed via rotary vacuum filtration for recycling of the liquid fraction and composting of the solid fraction.

Wine is cooled rapidly to facilitate the precipitation of tartrate crystals. Fining is applied for the separation of suspended particles using bentonite and gelatin. Filtration is subsequently applied to remove any insoluble compounds. The wine is finally transferred into bottles.

The main differences in the red wine production process are skin maceration duration, fermentation temperature, and unit operation sequence. Whole crushed grapes are most frequently used in red wine fermentation, which is carried out at 22C28C to facilitate the extraction of color and flavors. The remaining skins, seeds, and grape solids after fermentation are pressed to recover wine with the correct proportions of tannins and other compounds necessary for the final wine product.

jaw crushers | mclanahan

jaw crushers | mclanahan

Jaw Crushers are used to reduce the sizeof many different types of materials in many applications. The Jaw Crusher was first introduced by Eli Whitney Blake in 1858 as a double-toggle Jaw Crusher. Introduced in 1906, McLanahans Universal Jaw Crusher was one of the first modern era overhead eccentric Jaw Crushers. On the overhead eccentric style Jaw Crusher, the moving swing jaw is suspended on the eccentric shaft with heavy-duty double roll spherical roller bearings.

The swing jaw undergoes two types of motion: one is a swing motion toward the opposite chamber side (called a stationary jaw die due to theaction of a toggle plate), and the second is a vertical movement due to the rotation of the eccentric. These combined motions compress and push the material through the crushing chamber at a predetermined size.

More than 110 years of engineering and customer service experience keep customers running to McLanahan tomeet their production goals. McLanahan Jaw Crushers are proudly made in the USA and have imperial designs. With our grass roots design coupled with listening to customer needs for product enhancement over the years, McLanahan offers traditional hydraulic-shim adjustment Jaw Crushers as well asH-Series Jaw Crushers that featurehydraulic discharge setting adjustment, adjust-on-the-fly chamber clearing in the event the site loses power (once power is restored) and hydraulic relief for overload events with auto-reset.

Whether the traditional hydraulic-shim adjustment or the H-Series Jaw Crushers, both machines have an aggressive nip angle that providesconsistent crushing throughout the entire crushing chamber, which leads to increased production and less downtime on maintenance.

A Jaw Crusher uses compressive force for breaking material. This mechanical pressure is achieved by the crusher'stwo jaws dies, one of which is stationary and the other is movable. These two vertical manganese jaw dies create a V-shaped cavity called the crushing chamber, where the top of the crushing chamber is larger than the bottom. Jaw Crushers are sized by the top opening of the crushing chamber. For example, a 32 x 54 Jaw Crusher measures 32" from jaw die to jaw dieat the top opening or gape opening and54 across the width of the two jaw dies.

The narrower bottom opening of the crushing chamber is used to size the discharge material. A toggle plate and tension rods hold the pitman tight near the bottom of the moving swing jaw. The toggle plate is designed to perform like a fuse and protect the crusher in the event that an uncrushable materialenters the crushing chamber. As a rule, Jaw Crushers have a 6:1 or 8:1 ratio for crushing material. Still using the 32 x 54 Jaw Crusher example, the top size of thefeed entering the crushing chamber has to follow the F80 rule that 80% of the top size feed material is smaller than the gape opening. Using the F80 rule with the 32 x 54 Jaw Crusher, the32 gape opening equals a26 top sized feed, and with the 6:1 ratio of reduction, the discharge setting would be around 4.

Since the crushing of the material is not performed in one stroke of the eccentric shaft, massive weighted flywheels are attached to the eccentric shaft andpowered by a motor. The flywheels transfer the inertia required to crush thematerial until it passes the discharge opening.

While Jaw Crushers are mostly used as the first stage of material reduction in systems that may use several crushers to complete the circuit, the Jaw Crusher has also been used as a second-stage crushing unit. Depending on the application requirements, Jaw Crushers can be used in stationary, wheeled portable and track-mounted locations. The Jaw Crusher is well suited for a variety of applications, including rock quarries, sand and gravel, mining, construction and demolitionrecycling, construction aggregates, road and railway construction, metallurgy, water conservancy and chemical industry.

F100 is the maximum gape opening on a Jaw Crusher. F80 is the feed size to the Jaw Crusher, calculated by taking 80 times the gape opening divided by 100. P80 is the percent passing the closed side setting in tph.

A best practice, if possible, is to blend the material arriving from the source. This will ensure a constant and well-graded feed to the crushing chamber. In turn, this will produce a steady rate of tph andpromote inter-particle crushing that helps break any flat or elongated material. It also aids in equal work hardening the manganese jaw dies and prolonging the life of the jaw dies.

Usually a Jaw Crusher is in an open circuit, but it can be used in a close circuit if the return load is not greater than 20% of the total feed and the raw feed is free of fines smaller than the closed side setting.

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.

jaw crushers - meka crushing & screening plants

jaw crushers - meka crushing & screening plants

Precision-machined, drop-forged, heat-treated Cr-Si-Mn-Mo SAE 4140 (42Cr, Mo4) steel eccentric shaft. The larger eccentricity of pitman shaft provides a motion that forces the material to the bottom of the jaw plate.

Spherical, self-aligning roller bearings, straight-bore pitman bearings and tapered-bore body bearings provide maximum strength to the pitman shaft and bearings for a long extended maintenance life.

The jaw crusher is one of the most indispensable and preferred machines because of its performance and durability. Depending on plant layout, jaw Crusher can be produced on wheels, skid-mounted or fixed to the concrete foundations.

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