understanding and use of the secondary crusher

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.

secondary & tertiary crushing circuits

In this sectoron Secondary and Tertiary crushing, we will continue the practice of talkingabout different equipment, the work it does, and the effects of what I call operating variables. These variables are anything that affect the performance of the equipment.

Lets begin with an over view of these two crushing stages. Then describe various flow sheets, and discuss the variables that influenced their design. After the whys have been given we will discuss the equipment and the operating techniques required to operate a modern crushing plant. The two major variables that determine the size of the crusher and the design of the flow-sheet are the tonnage through put required and the hardness of the ore. The tonnage will be determined by economic factors, namely what tonnage is required to make the mine profitable? The hardness of the ore is determined by what is known as the WORK INDEX. This measurement is determined by the resistance of the ore to breakage. It is discovered by the energy output required to reduce the ore to a specific predetermined size. It is measured by the KILOWATT PER HOUR usage of electricity required. Lets start with a very simple flow sheet. This one is designed for very soft rock, or where the product size isnt important.

The feed comes from the primary crusher and will have a certain amount of rock that doesnt need further crushing. To run this ore through the crusher will be a waste of energy and crushing space. Ideally it should be removed.

To remove it requires a procedure called SCALPING. This is when the ore is allowed to flow over a set of SCREENS or GRIZZLIES. The large ore wont be able to pass through the mesh, but the fine material will, this effectively separates the two sizes.

The ore is a little harder and the sizing more critical however, this means the positioning of the equipment has to change a little. The ore is still discharged from the primary crusher to the scalping equipment. For this type of application this is usually a screen. Again the fine material is removed from the circuit while the course gets crushed. But now, instead of continuing, the crushed product is directed back to the screen for further sizing. Any rock that isnt small enough will have to go through the crusher once more. Designing the circuit this way insures that the crushed rock has a uniform size.

Just for interest sake, the first circuit we looked at is called an OPEN CIRCUIT. This is because of the constant forward movement of ore. The second one is referred to as a closed circuit. That is because the ore must meet the circuits objective, in this case the correct size, before it is allowed to escape the closed loop of the crushing circuit.

Our last schematic represents a CLOSED CIRCUIT. This one involves both SECONDARY and TERTIARY crushing. This circuit is employed where either the tonnage or the work index of the ore is high enough to require that the crushing be done in stages.

Again the ore will come from a Primary crusher and be scalped. The coarse material will be crushed by the secondary crusher. The fines will be taken out of the circuit. Once the secondary has finished with the ore it will be reclassified by a second set of screens with the oversize going to the tertiary crusher. The discharge of the tertiary is reintroduced to the screen deck to ensure that the ore size is uniform. These three schematics are samples of crushing circuits. There are many other varieties, each one dictated by the requirements of the ore, and the economics involved. Although each mine has its own individual problems, and the resulting unique design, they do usually have one thing in common. Almost all secondary and tertiary crushing circuits use the same type of crusher, the cone crusher.

young adults understanding and use of data: insights for fostering secondary school students data literacy | springerlink

Data literacy has become an important part of STEM literacy and informed citizenship in our society. However, data literacy initiatives in secondary schools predominantly focus on narrow issues of developing students ability to work with quantitative data and fail to address students broader understanding both as producers and consumers of data. This study examined how secondary school students (N=27) understand data and its relevance in everyday life. Students responded to a short pre-project survey and worked on a biology inquiry project producing poster-based science news. We inductively coded text responses and created themes that represent students descriptions of data. We also analysed the nature of data students used while working on their project and producing posters. Results showed that students understanding of data were limited to contexts of (a) experiment and survey, (b) utility and usage information, and (c) numerical charts and graphs. However, students used broad range of data in their authentic projects compared to their written description. Results provide insight about designing data literacy interventions and the importance of developing students broader awareness related to the nature of data in everyday life.

La matrise du numrique occupe dsormais une place importante dans lalphabtisation scientifique en STEM et la citoyennet active et consciente dans notre socit. Cependant, les initiatives dans le domaine de la matrise numrique dans les coles secondaires sont centres principalement sur des questions troites telles que le dveloppement dhabilets permettant aux tudiants de manier des donnes quantitatives, sans se proccuper de leur comprhension, au sens large, de leur rle aussi bien comme producteurs que comme consommateurs de donnes. Cette tude analyse la faon dont des tudiants du secondaire (N=27) comprennent les donnes et leur pertinence dans la vie quotidienne. Les tudiants ont rpondu un bref questionnaire prliminaire, et ont travaill un projet denqute biologique dont le rsultat a servi produire des nouvelles scientifiques sur affiche. De manire inductive, nous avons codifi leurs rponses textuelles et nous avons labor des thmes qui reprsentaient les descriptions des donnes proposes par les tudiants. Nous avons galement analys la nature des donnes utilises par les tudiants dans le cadre de leur projet et dans la ralisation de leurs affiches. Les rsultats montrent que la comprhension des donnes chez les tudiants tait limite aux contextes: a) dexprience et denqute, b) dutilit et dutilisation de linformation, et c) de tableaux et de graphiques numriques. Toutefois, les tudiants se servent dun vaste ventail de donnes dans leurs projets rels comparativement la description crite quils en font. Les rsultats fournissent des informations importantes pour la cration dinterventions visant amliorer la matrise du numrique, et soulignent limportance dencourager une meilleure conscience de la nature des donnes dans la vie quotidienne.

Athanases, S. Z., Bennett, L. H., & Wahleithner, J. M. (2013). Fostering data literacy through pre-service teacher inquiry in English language arts. The Teacher Educator, 48, 828. Authors concealed for blind review

Azevedo, F. & Mann, M (2018). The mathematics content of high school social sciences textbook. Paper presented at the Annual Conference of the American Educational Research Association (AERA). New York, NY.

Data Pop Alliance (2015). Beyond data literacy: Reinventing community engagement and empowerment in the age of data. White paper series. Retrieved from http://datapopalliance.org/item/beyond-data-literacy-reinventing-community-engagement-and-empowerment-in-the-age-of-data/. Accessed 12 July 2016

Gebre, E., Saroyan, A. & Bracewell, R. (2014). Students engagement in technology rich classrooms and its relationship to professors conceptions of effective teaching. British Journal of Educational Technology, 45 (1), pp. 8396

Hossain, M. A., Dwivedi, Y. K., & Rana, N. P. (2016). State of the art in open data research: insights from existing literature and a research agenda. Journal of Organizational Computing and Electronic Commerce, 26(12), 1440.

Kippers, W. B., Poortman, C. L., Schildkamp, K. & Visscher, A. J. (2018). Data literacy: What do educators learn and struggle with during a data use intervention? Studies in Educational Evaluation, 56, 2131

Matuk, C., Zhang, J., & Linn, M. C. (2017). How middle school students construct and critique Graphs to explain cancer treatment. In B. K. Smith, M. Borge, E. Mercier, E., and K. Y. Lim (Eds.). Making a difference: Prioritizing equity and access in CSCL, 12th International Conference on Computer Supported Collaborative Learning (CSCL) (pp. 375382). Philadelphia, PA: International Society of the Learning Sciences.

Philip, T. M., Olivares-Pasillas, M. C. & Rocha, J. (2016). Becoming racially literate about data and data-literate about race: Data visualizations in the classroom as a site of racial-ideological micro-contestations. Cognition and Instruction, 34(4), 361388.

Ridsdale, C., Rothwell, J., Smit, M., Ali-Hassan, H., Bliemel, M., Irvine, D. Wuetherick, B. (2015). Strategies and best practices of data literacy education: Knowledge synthesis report. Dalhousie University

Schneider, R. (2013). Research data literacy. In S. Kurbanoglu, E. Grassian, D. Mizrachi, R. Catts and S. piranec (Ed.), Worldwide commonalities and challenges in information literacy research and practice (pp. 134140). Cham: Springer International.

diSessa, A. A. (2002). Students criteria for representational adequacy. In K. Gravemiejer, R. Lehrer, B. van Oers, & L. Verschaffel (Eds.), Symbolizing, modelling and tool use in mathematics education (pp. 105129). Dordrecht: Kluwer.

Stanford History Education Group (2016). Evaluating information: The cornerstone of civic online reasoning. Retrieved from: https://stacks.stanford.edu/file/druid:fv751yt5934/SHEG%20Evaluating%20Information%20Online.pdf Accessed 13 February 2017.

Stephenson, E. & Caravello, P. S. (2007). Incorporating data literacy into undergraduate information literacy programs in the social sciences: A pilot project. Reference Services Review, 35(4): 52540.

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appropriate use of information at the secondary school level: understanding and avoiding plagiarism - sciencedirect

This study explores students' understanding of plagiarism and their information use practices. Based on earlier findings regarding students' orientation toward processes and the degree of plagiarism exhibited, it analyses four cases in a new Australian study of Year 11 students. The two students who plagiarized least are compared with the two who plagiarized most in an ancient history assignment. Those who plagiarized most were less engaged with their topics; remembered less about them a month later; demonstrated less interest in processes such as learning, seeking meaning, or understanding; and were less able to recognize plagiarism than did those who plagiarized least. Those who plagiarized least incorporated direct quotations more effectively, used fewer quotations, and synthesized information and ideas better than did the others. Learning experiences that emphasize student engagement and construction of knowledge through appropriate and effective information use should take precedence over attempts to detect plagiarism without providing alternatives.

primary crusher - an overview | sciencedirect topics

The primary crusher is located in the quarry and consists of a McLanahan 48x72 Shale King Crusher rated at 1,000 TPH (Tons Per Hour). The driving flywheel has a diameter of 2.5 meters and is motor driven through six v-belts. The capacity of the primary crusher had to be increased to 1,250 TPH to produce enough material to serve the wet and both dry lines in the plant. To enable the crusher to operate at the higher capacity, the manufacturer recommended grooving the flywheel for two additional v-belts. To avoid the costs of disassembling, shipping and reassembling, Nesher performed the machining in-place. The operation was performed using portable tools and an auxiliary motor that turned the flywheel for machining the new grooves.

Roll crushers are generally not used as primary crushers for hard ores. Even for softer ores, such as chalcocite and chalcopyrite, they have been used as secondary crushers. Choke feeding is not advisable as it tends to produce particles of irregular size. Both open and closed circuit crushing is employed. For close circuit the product is screened with a mesh size much less than the set.

Figure6.4 is a typical set-up where ores crushed in primary and secondary crushers are further reduced in size by a rough roll crusher in an open circuit followed by finer size reduction in a closed circuit by a roll crusher. Such circuits are chosen as the feed size to standard roll crushers normally does not exceed 50mm.

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.

Detail descriptions of designs are given of large gyratory crushers that are used as primary crushers to reduce the size of large run-of-mine ore pieces to acceptable sizes. Descriptions of secondary and tertiary cone crushers that usually follow gyratory crushers are also given in detail. The practical method of operation of each type of gyratory crusher is indicated and the various methods of computing operating variables such as speed of gyration, capacities and power consumption given are prescribed by different authors. The methods of calculations are illustrated to obtain optimum operating conditions of different variables of each type using practical examples.

Shale, a low-moisture content soft rock, is quarried, transferred to blending stockpiles before it is reduced by primary crushers and dry-milled to a powder of less than 250m. This powder is homogenized and stored ready for pelletization in manner similar to that used for making aggregate from PFA except that no fuel is added. However, after the pellets have been produced to the appropriate size, which depends on the expansion required, they are compacted and coated with finely powdered limestone. The resulting pellets are spherical with a green strength sufficient for conveying to a three-stage kiln consisting of a pre-heater, expander and cooler. Unlike other aggregates produced from argillaceous materials, the feedstock is reduced to a powder and then reconstituted to form a pellet of predetermined size. The expansion (bloating) is controlled during kilning to produce an aggregate of the required particle density. Different particle densities are produced by controlling the firing temperature and the rotational speed of the kiln. The coating of limestone applied to the green pellet increases the degree of surface vitrification which results in a particle of low permeability. This product gives versatility to the designer for pre-selecting an appropriate concrete density. As Figure7.6 shows, while the particle shape and surface texture of the aggregate remain essentially the same, the internal porosity can be varied according to the bloating required for the specified density.

Mined crushed stone is loaded into trucks or onto conveyors and transported to the processing facility. The broken stone is dumped into a primary crusher where the large rock fragments are broken into smaller sizes. Crushing to the proper size usually occurs in stages because rapid size reduction, accomplished by applying large forces, commonly results in the production of excessive fines (Rollings and Rollings 1996). After primary crushing, the material is run through one or more secondary crushers. These crushers use compression, impact, or shear to break the rock into smaller pieces. The material is screened after each crushing cycle to separate properly sized particles (throughs) from those needing additional crushing (overs). Additional washing, screening, or other processing may be required to remove undesirable material. The material is then stockpiled awaiting shipment.

After mining, sand and gravel may be used as is, which is called bank-run or pit-run gravel, or it may be further processed. The procedures for processing sand and gravel are similar to those for processing crushed stone. The amount of processing depends on the characteristics of the sand and gravel deposit and the intended use. If the gravel deposits contain very large cobbles or boulders, that material may be run through a primary crusher. The material may be run through one or more secondary crushers, then washed, screened, or further processed to remove undesirable material. The material is then stockpiled awaiting shipment.

The design of belt and apron feeders is fairly standardized, and most of the producing companies use pre-defined models and calculation methods to get short delivery times with a low-cost approach. The main features of the apron and belt feeders are:

Although the conveying devices are reasonably well defined and standardized, there is still room for improvement of the overall plant layout and construction, e.g. crushing plant, silo discharge system, train unloading system, etc. One of the most obvious ways to improve the overall design of such systems is to develop a better understanding of the equipment itself. Today, most OEMs want to be involved in the process of seeking the solution rather than only the supply of the equipment. This will enable the market to make use of the expertise of the equipment supplier and, at the same time, use their knowledge base for developing a wider scope, including other aspects such as silo design, hopper design, electrical and hydraulic issues, etc.

Highland Valley copper mine experienced a decline in mill throughput after implementing larger holes for blasting, which resulted in coarser fragmentation and a coarser product from the primary crushers [24]. In the quarry at Vrsi, as drilling geometry decreased from 3.0m4.5m to 2.9m3.0m while other parameters such as borehole sizes were constant, a significant savings of 14% was achieved for the quarry [25]. Due to a mine-to-mill implementation at the Red Dog Mine, the mine achieved savings exceeding $30 million per year [26]. This indicates that, at least in some ores, improved internal fragmentation carries through the crushing and grinding circuits. The mine-to-mill project in the same mine identified further benefit, specifically the marked reduction in SAG feed size and throughput variability [5]. A second but important benefit was the reduced wear in the gyratory crusher, resulting in a significantly longer period between relines. When electronic detonators with very short delay time were applied in the Chuquicamata open pit copper mine, the fragmentation was markedly improved [27]. In the Aitik copper mine a raised specific charge from 0.9 to 1.3kg/m3 gave rise to an increase in the throughput by nearly 7% due to more fines produced and shorter grinding time achieved [28].

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.

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.

types of rock crushers | quarry crushing equipment | kemper

Do you need to process sand, gravel, minerals, rock, or other aggregate products and have not yet purchased or leased crushing equipment? Theres no questionyou need to work with a capable and professional material handling equipment design and engineering company dedicated to selling, renting, and installing the best new crushers for your needs.

However, if youre new to the aggregate processing industry, you probably have a lot of questions about rock crushers. As foundational material handling equipment in all plants, crushers need to coordinate seamlessly with screens, conveyor systems, and washing equipment.

It is common to use multiple crusher types within a project and set them up as stations in a circuit format to perform the necessary material reduction work. In many cases, primary, secondary, and tertiary, and quaternary stations are installed to reduce the rock to the desired size, shape, and consistency.

For instance, if the final size of your product only needs to be between 4 inches and 6 inches, a primary jaw or impact crusher can accomplish your goals. However, you will likely require a much finer product, and that means incorporating up to threeor even fourstations with a variety of crusher types.

As the first stage in a crushing circuit following extraction from a mine site, (or in the case of recycled asphalt production, delivery to the RAP processing plant via truck transport), primary crushing reduces material to a size and shape that can be handled by the secondary crusher.

Typically, the minimum setting on most primary crushers will be about 4 to 6 inches, as noted above. Compression-style jaw, cone, impact crushers, and gyratory crushers are most often appropriate as primary crushing equipment types, though there can be overlap between primary and secondary crushers as far as suitable types.

In secondary crushing, reduction ratios become an essential consideration. Knowing just how fine you need your final output to be, along with the feed requirements of your tertiary or final reduction crushing station, will help you determine how much reduction needs to take place within this stage.

Cone crushers are often placed within the secondary crushing station because they are versatile in terms of feed, closed side setting, speed, and throw. With cone crushers, though, it is essential to operate them at consistent choked settings to keep productivity up.

The goal of the tertiary (third), quaternary (fourth) or final reduction stage of the crushing process is to size and shape rock or other material into a marketable product. Again, there may be overlap between stages in terms of which crusher styles work best.

Sandstone, limestone, gravel, and granite are arguably the most common aggregates used in the construction industry today, but these rocks have very different hardness and abrasiveness characteristics.

The answer might be three to four if youre talking about setting up stations in a complete rock crushing plant. Those are the primary, secondary, and tertiary/quaternary/final reduction rock crushers, which we covered above.

Of course, there are also different styles of rock crushers. Compression-style jaw and cone crushers, for example, fit into the various stations in a crushing circuit (depending on factors like the sizes, varieties, and hardness of the rock you need to crush, as well as the necessary output).

The number of crusher types in terms of style and configuration can be more challenging to quantify, as there are lots of ways to customize rock crushers. However, youll find four basic designscone, jaw, gyratory, and impact crushersoperating within many crushing plants.

Jaw crushers are also known as rock breakers and are used to break up larger, harder materials into more manageable pieces. They tend to do well with many different types of materials and dont display as much wear and tear as impact-style rock crushers. They also produce minimal fine materials and dust, though the finished product with this type of rock crusher almost always requires secondary crushing.

To learn more about jaw crushers, youll want to catch our previous blog post all about these tough pieces of material handling equipment and the most common questions operators have about jaw crushers.

Cone crushers can accept medium-hard to very hard and abrasive feeds that might be dry or wet, though not sticky (whereas gyratory crushers are better at handling softer, dryer feeds). Their output will be a relatively cubical product, with a reduction ratio of about 6-to-1 through 4-to-1.

Impact-style crushers include VSIs, as well as horizontal shaft impactors (HSIs), and are best used with less abrasive rock types, like limestone. These types of machines break apart material by the impacting forces of certain wear parts known as blow bars and impact plates or toggles.

Some operations also use impact-style crushers after they have already used a different type of rock crusher that produces a more elongated stone. This helps further shape the crushed material into a finer consistency with a more cubical nature.

Impact crushers tend to be less expensive than compression crushers (aka cone and jaw crushers, which we already covered) and have a higher reduction ratio. They can also break sedimentary deposit-type rockslimestone and similaralong natural lines, which rounds off sharp angles and weak edges. This can produce a result that is more sand-like in nature.

Drawbacks of impact crushers include their tendency to produce an excess of fine materials if used with softer rocks. Impact rock crushers can also require frequent part changes and can create a large amount of dust that can be an issue on some worksites.

Stationary plants have long been preferred because they feature a higher capacity and efficiency and lower production costs with easier maintenance. They also have historically featured a lower energy cost if you have on-site electricity, and no additional equipment is needed to move them from place to place.

Its true that portable material handling equipment already offers unmatched production flexibility. For instance, if you need to move your crushing plant more than once a year to multiple job sites, you are likely better off investing in portable equipment.

These self-contained plants are better suited to smaller projects and can be moved from project to project as necessary. They are often still not quite as efficient and have less capacity than stationary plants, but they can be more cost-effective in the long run if you have multiple projects in different areas.

Here at Kemper Equipment, we offer the best performing crushing equipment that will work hard to make any finished products you plan to produceincluding sand, gravel, fertilizer, specialty mineral products, recycled asphalt, salt, coal, and slagefficiently and affordably. Contact us today to discover how we can provide a custom-designed crushing circuit or retrofit a new rock crusher into your existing operation.

rock crusher - eastman rock crusher

Granite is not easy to crush to sand, main equipment has PE-7501060 jaw crusher (coarse crusher), HP300 cone crusher (fine crusher), bin, 490110 vibrating feeder, B1000x22 conveyor belt, B1000x30m conveyor belt, B800x31 conveyor belt, 4YK2460 vibrating screen, etc. contact us!

In this case, we recommend the use of a PCZ1308 heavy hammer crusher with a feed size of 930x650mm, the feed particle size is less than 600mm, the motor power is 4P 132Kw, and the processing capacity of the equipment is 100-180t/h.

Eastman is a typical direct selling enterprise with green and standardized production plants. All the delivery of the equipment will be completed within the delivery period signed by the contract to ensure the smooth commissioning of the equipment.

Rock crushers have a wide range of suitable material to choose from, whether its soft or hard, or even very hard, rock crushers can reduce those large rocks into smaller rocks, gravel, or even rock dust.Here are some typical materials that break or compress by industry crushers, such as Granite, quartz stone, river pebble, limestone, calcite, concrete, dolomite, iron ore, silicon ore, basalt and other mines, rocks and slag.

Understanding the stages of crushing process and the types of crushers that best fit each stage can simplifies your equipment selection. Each type of crusher is different and used to achieve a certain end result.

Similarly, a certain output is expected at the end of each crushing stage for the next phase of the process. Aggregate producers who pair the correct crusher to the correct stage will be the most efficient and, in turn, the most profitable.

A jaw crusher is a compression type of crusher. Material is reduced by squeezing the feed material between a moving piece of steel and a stationary piece. The discharge size is controlled by the setting or the space between those two pieces of steel. The tighter the setting, the smaller the output size and the lower the throughput capacity.

As a compression crusher, jaw crushers generally produce the coarsest material because they break the rock by the natural inherent lines of weakness. Jaw crushers are an excellent primary crusher when used to prepare rock for subsequent processing stages.

Although the chamber is round in shape, the moving piece of steel is not meant to rotate. Instead, a wedge is driven around to create compression on one side of the chamber and discharge opening on the opposite side. Cone crushers are used in secondary and tertiary roles as an alternative to impact crushers when shape is an important requirement, but the proportion of fines produced needs to be minimized.

An impact crusher uses mass and velocity to break down feed material. First, the feed material is reduced as it enters the crusher with the rotating blow bars or hammers in the rotor. The secondary breakage occurs as the material is accelerated into the stationary aprons or breaker plates.

Impact crushers tend to be used where shape is a critical requirement and the feed material is not very abrasive. The crushing action of an impact crusher breaks a rock along natural cleavage planes, giving rise to better product quality in terms of shape.

Most aggregate producers are well acquainted with the selection of crushing equipment and know it is possible to select a piece of equipment based solely on spec sheets and gradation calculations. Still, theoretical conclusions must always be weighed against practical experience regarding the material at hand and of the operational, maintenance and economical aspects of different solutions.

The duty of the primary crusher is, above all, to make it possible to transport material on a conveyor belt. In most aggregate crushing plants, primary crushing is carried out in a jaw crusher, although a gyratory primary crusher may be used. If material is easily crushed and not excessively abrasive, an impact breaker could also be the best choice.

The most important characteristics of a primary crusher are the capacity and the ability to accept raw material without blockages. A large primary crusher is more expensive to purchase than a smaller machine. For this reason, investment cost calculations for primary crushers are weighed against the costs of blasting raw material to a smaller size.

A pit-portable primary crusher can be an economically sound solution in cases where the producer is crushing at the quarry face. In modern plants, it is often advantageous to use a moveable primary crusher so it can follow the movement of the face where raw material is extracted.

The purpose of intermediate crushing is to produce various coarser fractions or to prepare material for final crushing. If the intermediate crusher is used to make railway ballast, product quality is important.

In other cases, there are normally no quality requirements, although the product must be suitable for fine crushing. In most cases, the objective is to obtain the greatest possible reduction at the lowest possible cost.

In most cases, the fine crushing and cubicization functions are combined in a single crushing stage. The selection of a crusher for tertiary crushing calls for both practical experience and theoretical know-how. This is where producers should be sure to call in an experienced applications specialist to make sure a system is properly engineered.