Building gravel & sand is the most widely used building material in road and bridge construction. It can be directly used in the construction application, and can also be processed into aggregates of various size apply in the asphalt and cement making. According to the technical standards, the natural stone materials for road construction are divided into four grades to meet the different requirements of the construction site.
Squeezing. The rock is subjected to pressure between the two planes, the force which exceeds the compressive strength of the stone makes the stone break into smaller pieces. Split. Under the action of the wedge, the tensile stress is generated in the stone. When the tensile stress exceeds the tensile strength of the stone, then be broken. Fracture. Under the action of multi fulcrum staggered force, the stone is subjected to shear and bending stress. When these stresses exceed a certain limit, the stone will be sheer or bending broken.
The crusher can be divided into three types according to the particle size of the feed and the final product. Primary crusher( from 1500-500mm to 350-100mm); secondary crusher( from 350-100mm to 100-40mm); tertiary crusher( from 100-40mm to 30-10mm).
Crusher also can be classified according to the working principle and mechanical structure. Jaw Crusher. When the movable jaw plate close to the fixed jaw plate, creates a squeezing force act on the stone. in addition, there is jagged steel on the rock material contacting surface of the fixed plate and Fracture. When the movable plate apart from the fixed plate, the crushed material is discharged under the gravity force. The process of crushing is that the process of breaking large particle material into smaller size under the action of external force. In industry applications, the size reduction task mainly depends on the mechanical force. Because of the jaw crusher working principle that crushes the material by reduced space between two plates, the aggregate product often has a high content of needle shape, which is not suitable for asphalt processing road construction. Therefore, the jaw crusher is widely used as primary crusher rather than secondary crusher in the mineral processing, aggregate processing industry.
Crushers are divided into three categories according to their crushing stage. They are (i) primary crusher, (ii) secondary crusher and (iii) tertiary crusher. The primary crusher receives materials directly from the mine (ROM) after sandblasting and reduces the size for the first time. The output of the main crusher is sent to the auxiliary crusher, which further reduces the size of the material. Similarly, the output of the secondary crusher is fed to the tertiary crusher, which further reduces the material size. Before reducing to the required size, some materials may go through four or more crushing stages. As a means of tightly controlling product size and limiting waste, the degree of crushing is distributed in multiple stages.
Crushers are also classified by mechanically transferring crushing energy to the material. Jaw, rotary and roller crushers work by applying pressure, while impact crushers such as hammer crushers achieve crushing by applying high-speed impact forces.
Jaw crusher is used as primary crusher. It uses compressive force to destroy the material. The mechanical pressure is obtained through the two jaw plates of the crusher. The reduction ratio is usually 6: 1. The jaw crusher consists of two vertical jaws installed in a V shape, the top of the jaw is farther than the bottom.
One jaw remains stationary and is called a fixed jaw, while the other jaw is called a swing jaw and moves back and forth relative to this jaw through a cam or link mechanism. The volume or cavity between the two jaws is called the crushing cavity. The movement of the swinging claw may be very small, because it will not be completely squeezed in one stroke. The inertia required to crush the material is provided by a counterweight flywheel that can move the shaft, causing an eccentric motion, which causes the gap to close.
The feed enters the crusher from the top, and the blocks between the blocks are broken. Jaw crushers are heavy machines, so they need to be durable. The outer frame is usually made of cast iron or steel. The jaws themselves are usually made of cast steel. They are equipped with replaceable lining made of manganese steel or Ni-hard (Ni-Cr alloy cast iron). Usually both jaws are covered with a replaceable lining. Also in some types, the bushing can be turned upside down after a period of time, thereby extending the replacement time.
The basic concept of a gyratory crusher is similar to a jaw crusher. It consists of a concave surface and a conical head. Both surfaces are usually lined with manganese steel. The inner cone has a slight circular motion, but does not rotate. This movement is generated by the eccentric device. The crushing effect is caused by the narrow gap between the bushing line (movable) installed on the central vertical main shaft and the recessed bushing (fixed) installed on the main frame of the crusher. The gap is opened and closed by an eccentric wheel at the bottom of the main shaft, which causes the center to rotate perpendicular to the main shaft. The vertical spindle can rotate freely about its own axis.
The material moves downward between the two surfaces that are gradually crushed until it is small enough to fall out through the gap between the two surfaces. Rotary crusher can be used for primary or secondary crushing.
Cone crusher consists of crushing cavity, crushing cone and operating mechanism. The cone is built into the vertical shaft, which is supported from the top by a bowl-shaped bearing and from the other end to the eccentric operating mechanism.
The operation of the cone crusher is similar to the rotary crusher, the steepness of the crushing cavity is smaller, and the parallel areas between the crushing areas are more. The cone crusher crushes the material by squeezing the material between an eccentrically rotating main shaft (the main shaft is covered by a wear sleeve) and a closed recessed hopper (the recessed hopper is covered by a manganese recess or a bowl lining). When the material enters the top of the cone crusher, the material will be wedged and pressed between the shell and the bowl-shaped lining or recess. Large pieces of material are shattered once, then descend to a lower position (because they are now smaller), where they are shattered again. Continue this process until the pieces are small enough to fall through the narrow opening at the bottom of the crusher.
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 . 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 . 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 . 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 . 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) . 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 . This phenomenon is detrimental when it comes to some applications, such as rock crushing . Work-hardening behavior of Hadfield steel has been attributed to dynamic strain aging . 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 , 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 . 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 .
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 . 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 .
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 , which appears when the phosphorus content exceeds 0.04% . 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 . However, in solution-treated conditions austenitic manganese steel structure is essentially austenitic because carbon is in austenite solution . The practical limit of carbon in solution is about 1.2%. Thereafter, excess carbon precipitation to the grain boundaries results, especially in heavier sections .
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 . 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 220.127.116.11.2.1.4).
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.
Crushers are mainly used for crushing stones or mineral ores, recycling construction waste, and producing aggregate. This equipment aims to reduce large solid raw material masses into smaller sizes. They also help to change waste material form so that they can be simply disposed of or recycled. They can also be used for secondary and tertiary crushing to produce the finished product and crushing materials between two parallel solid surfaces.
In an ever-changing industry, waste is one of the major issues for companies when it comes to maximising profits and winning tenders. With the proper application of crushing materials can be reused in other areas of industrial applications.
The primary crusher is only for the breaking of large stones into pieces (this means primary crusher is not for the aggregate size material.). Examples of primary crushers are jaw crusher; hammer mill crusher and gyratory crusher. After receiving the primary crusher crush the material and produce a new fresh reduced size of the source material. The primary crusher has only functioned up to that point. A secondary crusher comes into action and further reduces the size. In secondary crushers some sizes of stones may pass directly from sieve number At the end tertiary crusher reduces the size of crushed pieces very much to the required size and it also brings the fineness to the crushed material. Tertiary crushers are at the job site and these are small in size.
A Jaw Crusher is one of the main types of primary crushers in a mine or ore processing plant. The size of a jaw crusher is designated by the rectangular or square opening at the top of the jaws. Primary jaw crushers are typical of the square opening design, and secondary jaw crushers are of the rectangular opening design. A Jaw Crusher reduces large size rocks or ore by placing the rock into compression. A fixed jaw, mounted in a V alignment is the stationary breaking surface, while the movable jaw exerts a force on the rock by forcing it against the stationary plate. Due to their smaller physical size, jaw crushers are also ideal for tight spaces, such as underground mining and mobile crushing applications.
Newer jaw crusher models are more focused on safety and easy maintenance. Hydraulic separation and individual lifting of shells are in a trend that creates a better environment for any workers on-site working with the equipment
An impact crusher is a machine that uses striking as opposed to pressure to reduce the size of a material. Impact crushers are designated as a primary, secondary, tertiary or quaternary rotor crusher depending on which processing stage the equipment is being utilized. Impact Crushers may be used as primary, secondary, or tertiary crushers depending on the Producers final-product-size needs. Impact Crushers are available in stationary, track, and portable configurations meeting any demand for any of these industries. Although Impact Crushers generally have a higher operating cost than other crushers, they tend to produce a more uniform particle shape (cubical) which is desirable and produces more fines for hot asphalt producers. Common types of Impact Crushers are Horizontal Shaft Impactor (HSI) and Vertical Shaft Impactor (VSI).
The new hybrid models of impact crusher are engineered for maximum feed size, target output size, and total capacity. The newer models are capable of producing construction-grade aggregate, artificial sand and stone materials, run of mine material, especially for the secondary and tertiary crushing stages.
Gyratory crushers are principally used in surface-crushing plants. The gyratory crusher consists essentially of a long spindle, carrying a hard steel conical grinding element, the head, seated in an eccentric sleeve. The spindle is suspended from a spider and, as it rotates, normally between 85 and 150 rpm, it sweeps out a conical path within the fixed crushing chamber, or shell, due to the gyratory action of the eccentric. Gyratory crushers provide high throughput and less downtime to bring maximum efficiency to your operation.
The new primary gyratory crushers have new advancements that bring increased speeds, higher installed power and mechanical improvements. All of these combine to bring additional throughput for your primary gyratory crusher.
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. The crushed material is discharged at the bottom of the machine after they pass through the cavity. Cone crushers are popular rock crushing machines in aggregate production, mining operations, and recycling applications. They are normally used in secondary, tertiary, and quaternary crushing stages.
The new hybrid models of cone crusher come with multi-cylinder hydraulic cone systems suited for the secondary or tertiary stages of crushing plants by changing body liners and adaptors. It comes with the automatic control and fingertip manipulation system and two hydraulic cylinders that have a protective effect that if one overloads, then another one can fast react to clear choke merely by remote control.
Stationary hybrid crushers combine the advantages of different roll crusher systems and are an ideal solution for primary, secondary and tertiary crushing applications. They have specially designed teeth, hydraulic gap adjustment, overload protection, and a scraper system perfect for dealing with sticky materials. These machines can work at capacities of up to 12,000 metric tons per hour, enabling you to keep productivity high whilst producing high-quality output.
The newer models have a compact design and take up minimal space. The crushing rolls are equipped either with crushing rings, segments, or crushing picks, depending on the application and feed material. The drive system for the rolls consists of individual electric motors for each roll, as well as couplings and gears. Standard components are used for cost-effectiveness and simpler maintenance.
The overall range of capacity for mobile impact crushers is roughly about 100 to 500 tons per hour. Todays mobile impact crushers are especially ideal for smaller-scale recycling operations, for on-site recycling, and tight-space urban and roadside applications. These units are transportable by trailer, simply driven off at the location of the material that needs to be processed, and go to work very quickly. With their capability to produce accurately-sized, cubical-shaped end-product, mobile impact crushers work well as stand-alone plants, or they can add significant productivity to any operation, working in tandem with a jaw crusher or screen plant.
The newer models use a direct drive system for optimum fuel efficiency and low operating costs and include several user-friendly features. This ensures that theyre both simple to operate, and easy to maintain.
This is a type of secondary or reduction crusher consisting of a heavy frame on which two rolls are mounted. These are driven so that they rotate toward one another. Rock fed in from above is nipped between the moving rolls, crushed, and discharged at the bottom.
The newer models offer belt-driven Roll Crushers in four designs: Single Roll, Double Roll, Triple Roll and Quad Roll Crushers, which provide a substantial return on investment by operating at low cost and maximizing yield by generating minimal fines. The rugged design, which incorporates a fabricated steel base frame lined with replaceable abrasion-resistant steel liners, stands up to the toughest mineral processing applications while providing safe and simple operation, including an automatic tramp relief system to allow uncrushable objects to pass while the crusher remains in operation.
The newer models of this machine generate high-quality aggregates, cubical in shape, with superior soundness. Available in three sizes, the HammerMaster is known for making excellent asphalt chip material, concrete stone, and general base material and road rock. This mill is also capable of making agricultural lime for pH control in farm fields.
Rod mills run along with the outside gear. Materials spirally and evenly enter the crushing chamber along the input hollow axis by input devices. Steel rods of different specifications are installed in the crushing chamber. When the frame rotates, centrifugal force is produced. At the same time, the steel rods are carried to some height and then fall to grind and strike the material. After grinded in the crushing chamber, the powder is discharged by an output material board.
The newer models of this machine are driven by motor with speed reducer and peripheral large gear, or low-speed synchronous motor with peripheral large gear. The grinding medium steel rod is put into the cylinder which is lifted, and then falls under the action of the centrifugal force and friction force. The materials entering into the cylinder from the feeding inlet are grinded by movable grinding medium and discharged out by overflow and continuously feeding.
A ball mill is a type of grinder used to grind, blend and sometimes for mixing of materials for use in mineral dressing processes, paints, pyrotechnics, ceramics and selective laser sintering. It works on the principle of impact and attrition: size reduction is done by impact as the balls drop from near the top of the shell. The newer models of this machine are widely used in cement, silicate products, new building materials, refractory materials, fertilizer, black and non-ferrous metals and glass ceramics and other production industries of all kinds of ores and other grind-able materials can be dry or wet grinding.
Manufacturers offering crushing equipment have expanded their respective ranges, offering additional capabilities for these segments. Mobility and versatility have been key factors in the development of new models, with many firms also offering new options in the shape of electric and hybrid drive systems.
A crusher is a machine that is designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size of materials, or change the form of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials so that pieces of different composition can be easy for next step separation.
As an old Chinese saying goes One must have good tools in order to do a good job. selecting an appropriate crusher, or indeed any parts of processing equipment, is very important in every quarry operation. And understanding what each crusher type is used for and knowing some general efficiency tips and the proper way to feed these machines will lead to the best results in your mining processing. Of course, each type of crusher is different and each of them is used to achieve a particular result. Likewise, to obtain a specific output, each type of crusher requires different maintenance tasks to keep it running efficiently. Operators who can achieve this, along with a consistent feed to the crusher, will be the most efficient and, more importantly, the most profitable.
Jaw crusher is used as primary crusher, its reduction ratio is usually 6:1. It uses compressive force to break the material, this mechanical pressure is achieved by the two jaws of the crusher. It is called a jaw crusher because it works the same was a human jaw does-food goes into your mouth and your bottom jaw pushes the food up against your fixed-top jaw. Inside the jaw crusher, is consisting of two vertical jaws installed to a V form, one jaw is kept stationary and is called a fixed jaw while the other jaw, called a swing jaw, moves back and forth relative to it, by a cam or pitman mechanism. where the top of the jaws are further away from each other than the bottom, so it can use a constantly moving metal piece that crushes the stones on a situated metal piece in small movements. Jaw crushers are classified on the basis of the position of the pivoting of the swing jaw
The type of jaw varies, which makes the different jaw crushers preferred for certain projects. For example, the Dodge crusher is used for laboratory purposes and not as heavy duty machinery because it can get clogged too easily, making it useless for large-scale projects.
In the Dodge type jaw crushers, the jaws are farther apart at the top than at the bottom, forming a tapered chute so that the material is crushed progressively smaller and smaller as it travels downward until it is small enough to escape from the bottom opening. The Dodge jaw crusher has a variable feed area and a fixed discharge area which leads to choking of the crusher and hence is used only for laboratory purposes and not for heavy-duty operations.
The jaw crusher is usually made of cast steel because it is such a heavy-duty machine. Its outer frame is generally made of cast iron or steel. While the jaws themselves are usually constructed from cast steel. They are fitted with replaceable liners which are made of manganese steel, or Ni-hard (a Ni-Cr alloyed cast iron). Usually, both jaws are covered with replaceable liners. Also in some types, the liners can be turned upside down after a while, extending the replacement time.
Similar to a jaw crusher, the gyratory crusher pulverizers the stones by placing them between two manganese steel plates and going straight down. It does not rotate, rather it is powered by electricity. Gyratory crushers are used in mine or ore processing plants and they can be used for primary or secondary crushing. It crushes rocks by rotating the vertical shaft and crushing the rocks in a circular motion where they fall out the narrow bottom when they are small enough.A gyratory crusher is used both for primary or secondary crushing.
Cone crusher is similar in operation to a gyratory crusher, but with less steepness in the crushing chamber and more of a parallel zone between crushing zones. A cone crusher breaks material by squeezing the material between an eccentrically gyrating spindle, which is covered by a wear resistant mantle, and the enclosing concave hopper, covered by a manganese concave or a bowl liner. As the material enters the top of the cone crusher, it becomes wedged and squeezed between the mantle and the bowl liner or concave. Large pieces of the material are broken once, and then fall to a lower position (because they are now smaller) where they are broken again. This process continues until the pieces are small enough to fall through the narrow opening at the bottom of the crusher.
A cone crusher is suitable for crushing a variety of mid-hard and above mid-hard materials. The feed is dropped to the crusher from the top and it is crushed between the crushing chamber and the slowly rotating cone.
Cone crushers are mostly used for the large scale crushing in the mining industry. It has the advantage of reliable construction, high productivity, easy adjustment and lower operational costs. The spring release system of a cone crusher acts as an overload protection that allows tramp to pass through the crushing chamber without damage to the crusher.
Impact crushers involve the use of impact rather than pressure to crush material. The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape. There are two types of impact crushers: horizontal shaft impactor and vertical shaft impactor. Impact crushers are suitable for materials that are soft or easily cleaving from the surface. The crusher consists of a fast spinning rotor and beaters attached to the rotor. The feed is entering to the crusher from the top and crushing starts immediately when the feed is impacted with beaters towards the crushers inner surface. Impact crusher can also be equipped with a bottom screen, which prevents material leaving the crusher until it is fine enough to pass through the screen. This type of crusher is usually used for soft and non abrasive materials.
Roll crushers crush the material use two opposite rotation of the rollers. The crushing is made up of electromotor, holder, fixed roller, movable roller and safety spring. The surface of the roller is mostly smooth. According to the number of rolls, there are single-roll, double-roll or multi-roll crushers. The double roll crusher is the most common rock stone crushing machine. Its crushing ratio is usually lower than in other crushers, so its suitable for fine crushing. The roll crusher uses compression to crush materials, and the reduction ratio is 2 to 2.5 so roller crushers are not recommended for abrasive materials.
Hammer crusher consists of a high-speed, usually horizontally shaft rotor turning inside a cylindrical casing. The crusher contains a certain amount of hammers that are pinned to the rotor disk and the hammers are swinging to the edges because of centrifugal force. The feed is dropped to the crusher from the top of the casing and it is crushed between the casing and the hammers. After crushing the material falls through from the opening at the bottom.
when selecting the correct crusher to best suit a particular operation, it is important to understand the requirements for each stage of crushing and how to properly feed each crusher. During the primary crushing stage, the aim is to get the material to a size that conveyors and other aggregate processing machines can handle. Generally, jaw crushers are installed at this crushing stage. Some operations will need further crushing in secondary and tertiary crushing stages. These stages are used to better control and size the output. Impact crushers and cone crushers tend to be used during these stages to better control particle size and shape. Understanding how to best match the type of crusher to the right crushing stage, as well as working with a manufacturer to properly size the crusher, will ensure crushing and feeding efficiency throughout an operation and, ultimately, overall profitability.
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Reducing the size of material for transport, building, and recycling is critical. Crushers were invented to make the task of breaking down rocks and other materials much easier. Although crusher technology is not particularly sophisticated, selecting the right crusher can take some time. In this article we discuss the different types of crushers and what you need to consider before you buy.
The first viable crusher (known as a mechanical rock breaker) was invented by Eli Whitney Blake in 1858. Another inventor, Philetus W. Gates, patented the first gyratory crusher in 1881. There were crushers patented before Whitneys, but they never made it into production. Since the late 1800s, the size of crushers has greatly increased, but the engineering principles that make them work have remained the same. Both jaw crushers and gyratory crushers are still used today.
The selection of any major piece of equipment entails having a detailed understanding of your job requirements. In choosing the right crusher you must know these key aspects of the material youll be handling:
Dimensions. What is the thickness, length, and width of the material you will feed into the crusher. A large crusher can process rocks up to three feet in diameter. A hydraulic hammer is used to break up larger pieces before they are fed into the crusher.
Obviously, dimension is in essence just measuring the maximum size of the material that will be fed into the crusher. The granulometric requirement is based on how the final product will be used. However, abrasiveness and hardness factor are known through testing and calculation.
The Rock Abrasiveness Index (RAI), introduced in 2002, is often used to categorize abrasiveness. This informs a rocks resistance to crushing as well as its wear and tear on the crusher. Highly abrasive rocks include granite, quartzite, and basalt.
As discussed in our article Get to Know the Common Types of Mining Equipment there are three classifications of crushers: primary, secondary, and tertiary. Crushers are further categorized by how they crush the material.
To understand the difference between the crushing phases, typical examples include reducing topsize from 900 to 300 mm for primary, 300 to 100 mm for secondary, and under 5mm for fine crushing, such as manufactured sand.
A jaw crusher is the most commonly used primary crusher. It uses simple technology to break down large blocks into smaller pieces. Their simplicity requires little engineering expertise to operate. A jaw crusher is reliable and needs less maintenance than other types of crushers.
A jaw crusher has one fixed and one moving surface in a V-shaped configuration. The moving jaw is mounted on an eccentric shaft. The reciprocal motion of this jaw presses the material against the fixed jaw. Rotational movement is achieved via a motor and a belt. The space between the jaws narrows as the material moves downward. Once crushed to the desired size, the material falls through the bottom of the jaw crusher.
An impact crusher (also called a hammer crusher) is quite versatile. It can be used as a primary, secondary, or tertiary crusher. Impact plates and beaters or hammers are used to break down the material. The material is fed through the upper part of the crusher then hit by hammers. Next, the pieces are thrown toward the plates. This further breaks the material. The pieces bounce back to the hammers. The material is thrown back and forth between the plates and hammers until it is reduced to the target size.
Impact crushers can handle an array of materials, including clay, dirt, and metal that may be mixed in with the feed material. An impact crusher can have a horizontal shaft or a vertical axis. This type of crusher may not be as effective for producing smaller pieces. The force needed to break down the material depends, in part, on the energy generated by the broken pieces. The smaller the piece the less energy its impact against the hammer produces. Impact crushers have a high production capacity, low energy consumption, and produce a uniform grain size. However, their operating costs are often higher than jaw crushers.
A cone (or conical) crusher breaks down material with the use of an eccentric rotating head and a bowl. It is often used as a secondary or tertiary crusher. It is best for crushing material 200 mm and less. Advantages of a cone crusher include high productivity and low operating costs. However, a cone crusher does not generate evenly sized pieces that are often required.
A gyratory crusher has a mantle that rotates within a concave bowl. Gyratory crushers and cone crushers are quite similar. A gyratory crusher has a higher angle at the apex of the cone. Its name refers to the constant back and forth motion that compresses the material against the chamber walls. They are often used as primary crushers.
There are mobile crushers that can maneuver around a job site. On some projects it is more cost-effective to not have to transport material to a centralized crusher for processing. Or a site is just too small for a large piece of equipment and requires a crusher with a smaller footprint.
The eccentric throw range is related to how much the crushers mantle veers away from its axis. This determines the rate the material will fall through the chamber. Crushers with a high eccentric thrown will allow particles to fall farther in a single revolution. This results in a coarser product.
Crusher technology keeps evolving in terms of automation and safety. Some of todays crushers are equipped with systems that will adjust the CSS (Closed Side Setting) without your having to shut the machine down. The crusher can ensure the bearings are not exceeding normal operating temperature. There are also safety features that will automatically shut down the machine when it encounters out-of-spec material, such as rubber or steel. This protects the shaft or bearing against damage. If youre working on a tight budget, we recommend machine power and brand name over bells and whistles. Larger organizations can usually justify high-cost automation features.
Eagle Crusher claims they sell the number one portable crusher worldwide. Their UltraMax Impactor line offers Horizontal Shaft Impactors (HSIs) that handle primary and secondary crushing in one unit. These units come in stationary, skid-mounted, or portable configurations. Eagle Crusher offers financing and 24/7 service. Made in the USA.
Powerscreen began as Ulster Plant in 1966 in Ireland. Its changed hands through the years but became Powerscreen in 2009. Its parent company is Terex. They manufacturer in several countries, including the US (in Louisville, Kentucky). They offer a wide variety of jaw, cone, and impact crushers. Their Metrotrak model is a compact, mobile unit offering an output of about 200 tph. It weighs around 60 thousand pounds. The Metrotrak is only 12.5 feet wide and a just under 41 feet long. Its low height of 10 foot, 6 inches gives you the ability to handle crushing in tight spaces.
They sell many types of crushers including several stationary cone crushers. Their CS420 is a high-production, compact stationary cone crusher. Sandvik offers their proprietary Automatic Setting Regulation control system (ASRi) This real-time performance management system will automatically adjust based on feed conditions. They also offer crushers that offer safety features and a system to streamline settings adjustment.
You can buy new or used directly from the manufacturer or a local equipment dealer. Financing options may be available. We recommend putting together a requirements document and letting the dealer tell you which crusher (or crushers) will meet your needs. Then you can shop it around for estimates.
Leasing is a great idea to try before you buy. However, depending on the size of your organization, it may make sense to take advantage of contract services that a company like Metso:Outotec offers. Compare it to the total cost of ownership. Its not just the cost of the machine its maintenance and repairs, hiring operators, and storing the equipment.
Buying used is only risky if you dont work with a reputable dealer. Youll want an experienced and knowledgeable operator to perform the inspection. Warranty and service agreements must be in writing. Be sure to understand what the resale value might be. Some brands and models hold their value more than others.
When youre inspecting a used crusher, take a close look at the wear parts. These are parts of the machine that are expected to be replaced periodically. For example, manganese liners protect the mantle and concaves of a cone crusher. The fixed jaw of a jaw crusher is subject to the most wear and tear. (In fact, Hardox offers cheek plates made of a material that they claim can greatly increase the life of your jaw crusher.) Take an inventory of worn parts and get quotes for replacements. There are companies that specialize in spare crusher parts such as Norther Crusher Spares.
Selecting the right crusher is highly dependent on your job requirements. Crushing rock and other hard materials is not a complicated process but selecting the wrong machine for the job can be dangerous. Low production or results of the wrong size grain can have a negative impact on your bottom line. Work with your local equipment dealer to select a machine that will meet your documented requirements. Explore safety and other automation features that will protect your workers and reduce production costs.
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