Usually mounted on a tyre or crawler frame and self-powered or moved using a tractor, mobile crushing plants are often used for on-site operations due to their great flexibility to be moved whenever required. The advantages of using a mobile crushing plant are the savings in transport and infrastructure costs, the ability to crush on site and move at any time; in addition, mobile crushing plants have good asset retention and are popular with project contractors and machinery rental companies.
In the construction and demolition waste disposal sector, mobile crushing plants are used to process concrete, asphalt and other demolition debris, not only to recover useful construction aggregates, but also to reduce transport and landfill costs.GEP Ecotech's mobile jaw crushers, mobile impact crushers, and mobile screening machines have been used in different projects in many places around the world for many years, and their excellent performance and reliability have been continuously proven in practice.
When the mobile crusher plant moves, it is powered by the power system and the crawler chassis is driven by the hydraulic electric control system; during installation, the power system automatically completes the installation of the equipment by driving the hydraulic cylinders and other movements through the hydraulic electric control system control; during operation, the power system drives and controls the mainframe and auxiliary equipment through a hydraulic electric control system. The material enters the mainframe mounted on the tracked chassis and frame and is discharged through an integrated belt conveyor after being crushed and sorted.
GEP Ecotech's mobile crushing plants are available on both tire and crawler chassis, with the tire chassis crushing plants using tractor-trailers for easy and cost-effective for long-distance transfers. Crawler chassis crushing plants are diesel or electrically powered with high passability. Allowing freedom of movement around the job site.
GEP Ecotech's mobile crushing plants are available on both tire and crawler chassis, with the tire chassis crushing plants using tractor-trailers for easy and cost-effective for long-distance transfers. Crawler chassis crushing plants are diesel or electrically powered with high passability. Allowing freedom of movement around the job site.
Masaba stocks all types of portable plants for crushing and are fabricated with quad-axle, stepped-frame, and road portable chassis, giving you the strength and versatility you need for your application.
We proudly partner with crusher brands like Metso, Cedarapids and Hazemag. We can standardize your portable crushing plant with components of the same company or we can work with you to build a fully customizable plant.
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A crushing plant delivered ore to a wet grinding mill for further size reduction. The size of crushed ore (F80) was. 4.0mm and the S.G. 2.8t/m3. The work index of the ore was determined as 12.2kWh/t. A wet ball mill 1m 1m was chosen to grind the ore down to 200 m. A 30% pulp was made and charged to the mill, which was then rotated at 60% of the critical speed. Estimate:1.the maximum diameter of the grinding balls required at the commencement of grinding,2.the diameter of the replacement ball.
A 1.0 1.5m ball mill was loaded with a charge that occupied 45% of the mill volume. The diameter of balls was 100mm. The mill was first rotated at 25rpm. After some time, the rotation was increased to 30rpm and finally to 40rpm. Determine and plot the toe and head angles with the change of speed of rotation.
A 2.7m 3.6m ball mill was filled to 35% of its inner volume. The charge contained 100mm diameter steel balls. The mill was rotated at 75% of critical speed. The ore size charged was 2.8mm and the product size (P80) of 75 m. The work index of the ore was 13.1kWh/t. Determine the production rate of the mill when operated under wet conditions.
Hematite ore of particle size 4000 m is to be ground dry to 200 m (P80). The work index of the ore was determined and found to be equal to15.1kWh/t. Balls of diameter 110mm were added as the grinding media. The mill was rotated at 68% of the critical speed and expected to produce at the rate of 12t/h. The combined correction factors for Wi equalled 0.9. Calculate:1.the volume of the mill occupied by the grinding media,2.the mill capacity when the mill load was increased by 10% of its original volume.
The feed size of an ore to a 1.7m 1.7m wet ball mill operating in closed circuit was 5000m. The work index of the ore was determined under dry open circuit conditions and found to be 13.5kWh/t. The mill bed was filled to 30% of its volume with balls of density 7.9t/m3. A 20:1 reduction ratio of ore was desired. The mill was operated at 80% of the critical speed. Assuming a bed porosity of 40%, estimate the mill capacity in tonnes per year.
A ball mill is to produce a grind of 34 m (P80) product from a feed size of 200 m at a rate of 1.5t/h. The grinding media used was 90% Al2O3 ceramic ball of S.G. 3.5. The balls occupied 28% of the mill volume. The mill was rotated at 65% of the critical speed. The work index of the ore was 11.3kWh/t. Estimate the size of the mill required.
A wet overflow ball mill of dimensions 3.05m 3.05m was charged with nickel ore (pentlandite) of density 4.2 having a F80 value of 2.2mm. The mass of balls charged for grinding was 32t, which constitutes a ball loading of 35% (by volume). The mill was rotated at 18rpm. Estimate:1.power required at the mill shaft per tonne of ball,2.power required at the mill shaft when the load (% Vol) was increased to 45%.
A grate discharge mill of dimensions 4.12m 3.96m was loaded to 40% of its volume with gold ore. The mill drew 10.95kW power per tonne of balls. To grind the ore to the liberation size the mill was run at 72% of the critical speed when charged with balls 64mm in size and 7.9t/m3 density. Determine:1.the fraction of the mill filled with balls,2.the mass of balls charged.
The feed size to a single stage wet ball mill was 9.5mm of which 80% passed through a 810 m sieve. The mill was expected to produce a product of 80% passing 150 m. The feed rate to the mill was 300t/h. The ball mill grindability test at 65 mesh showed 12kWh/t. The internal diameter of the ball mill was 5.03m and the length-to-diameter ratio was 0.77. The steel balls occupied 18% of the mill. The total load occupied 45% of the mill volume. If the mill operated at 72% of the critical speed, determine:1.the mill power at the shaft during wet grinding,2.the mill power at the shaft during dry grinding.
A 5.5m 5.5m ball mill is lined with single wave liners 65mm thick, which cover the entire inside surface. The centre line length was 4.2m and the trunnion diameters 1.5m in diameter. The mill was charged with an ore and 100mm diameter steel balls as the grinding media so the total filling of the cylindrical section was 40% and the ball fractional filling was 0.15 %. The slurry in the mill discharge contained 33% solids (by volume). The mill was expected to rotate at 12.8rpm. Estimate the total power required (including the power required for the no load situation).
There is now a new generation of mobile crushing and screening plant systems, which have been developed based on the motivation of reducing truck haulage. Newly designed mobile crushing and screening plant systems have the advantages of mobility, flexibility, economy, and reliable performance, making this system very appealing for small- to medium-sized projects or projects where a number of resources are separated by distance. Similarly, the advantages of mobile crushers are lower capital cost (up to 30% less), higher mobility, and higher salvage value at the end of the project life. Mobile crushing plants are not suited to large long-life projects, heavy rainfall climates, or arctic climates. The design considerations, operability, and maintainability require careful consideration. The equipment selection would also be based on different criteria to fixed plant (Connelly, 2013).
The iron ore lump obtained from ROM crushing and screening plants will continue to break down into 6.3mm particles during material handling from the product screen to stockpiles, port, and customer. Drop test conditioning of diamond drill core and crusher lump samples has been developed to simulate material handling and plant stockpiling (Clout et al., 2007). The outcomes of the lump simulations in Figure 2.9 indicate that most of the breakage of lump to 6.3mm fines occurs after the first significant drop height; thereafter, the lump consistently shows the same lower rate of breakage to the extent of testing. Breakage functions can be developed, like the curves in Figure 2.7, for specific iron ores and their hardness categories and then used in subsequent plant engineering design and lump degradation modeling. Different iron ores will show different breakdown characteristics, with very hard iron ores showing a slower rate of breakdown, whereas friable lump breaks down so rapidly that it is unlikely to be economically viable as a lump product (e.g., Figure 2.9, ROM 15 Friable).
Figure 2.9. Simulation of lump yield with cumulative mechanical breakdown in material handling from crusher to port. Lump yield for various hardness types derived from crushing and screening of run-of-mine (ROM) feed.
Large volumes of concrete derived from reliable consistent sources can be regarded as virtual quarries where a mobile crushing plant is used at the site. Examples include RCA derived from the decommissioning of concrete pavements from redundant military airfields or demolition of large concrete framed buildings/industrial facilities.22 In such cases, the availability of a material of consistent quality in large quantities makes their exploitation attractive.
In the UK, there are a growing number of processing centres which combine conventional aggregate processing equipment (such as crushers and screens), with a washing plant. Such facilities have the ability to handle mixed construction demolition and excavation waste (including soil). For commercial reasons, the main output is generally a range of RA products (such as unbound fills, capping, sub-base and pipe bedding) rather than a segregated RCA.15
Annually 1 million tons of mineral demolition wastes mainly consisting of concrete and bricks, is produced in Finland. The crushed materials have in field studies on test roads showed favourable geotechnical properties for use in road constructions. The test samples from two crushing plants were chemically characterised and the leaching behaviour was studied by using column, two-stage batch leaching and pH static tests. Only sulphate and chromium leaching from the crushed material was detected. There was a good agreement between column and batch leaching tests. The contents of harmful organic compounds were very low. Based on experience and the results of the experimental study, a practical sampling and testing strategy for an environmental quality assessment system was developed. A two-stage batch leaching test was chosen for the quality control of demolition waste. Preliminary target values for leaching of sulphate, Cr, Cd, Cu and Pb were set. Both geotechnical and environmental properties of the crushed material indicate that the use of demolition waste in road constructions is acceptable and can be recommended to replace landfilling of this material. However, a detailed demolition plan is most important in order to have an acceptable material for utilisation in earth constructions.
Building garbage recycling equipment in Western developed countries is generally mobile crushing station and mobile screen station, which can be divided into two categories, i.e., wheeled and tracked, shown in Figs 8.5 and 8.6. They can be used either alone or in combination with multiple devices. Characteristics of rubber-tired mobile crushing plant are as follows:
the installation form of integrated complete sets of equipment eliminates complex installation work caused by site and infrastructure of fission components, thus cutting down the consumption of the material and working hours.
The machine adopts all-wheel drive and it can realize spin insitu. Standard configuration and quick change device with perfect function of security protection is especially suitable for narrow space and complex area.
Compared with the traditional crushing screening equipment, the mobile crushing station has characteristics of mobility, reconfigurability, and automation. The crushing, screening, and debris sorting of construction waste can be realized if these features are applied to the recycling of construction waste, which can completely meet the requirements of comprehensive treatment of construction waste. In addition, the combination of different types of mobile crushing station screened by the mobile screen substation, which manage the primary and secondary crushing of construction waste, cannot only improve the performance of recycled aggregates, but also get the recycled aggregates piled up in accordance with the aggregate graded, facilitating the recycle of recycled aggregates.
In the process of construction waste treatment with mobile crushing station, the interaction of the waste concrete with itself contains a mix of collision and friction with each other using vibrating equipment, such as vibrating feeder and the original vibrating screen, which can reduce relatively loose waste mortar on its surface. Compared with the mechanical rub method, there is an effect gap between the two, but it plays the same role as well, which improves the performance of the recycled aggregates to some extent.
New renewable equipment can not only break, but also sieve. Mobile crushing screening equipment produced by Atlas Copco, take PC1375 type I crusher, for example, its high efficiency and flexibility, simplicity of operation, product design for easier transportation make it very suitable for field use in harsh environment, and most important of all, products broken by this device is of high capacity and good quality. PC1375 type I crusher is equipped with a special design of 19-mm-thick conveyor belt with high-strength steel wire, which effectively prolongs its service life. Its standard configuration is high-intensity magnetic belt, which can separate all the metal materials out before conveying crushing material to the dump, producing clean broken end products and the separated metal materials can earn extra income. The discharging mouth of the crusher is equipped with rollers, the impact absorption plate with special design is composed of replaceable rubber and steel, and the conveyor belt is removable, which makes obstruction cleaning and equipment maintenance very convenient.
There are, however, an increasing number of urban buildings built using contemporary earth walling, particularly in Western Australia where the revival of rammed earth as a modern building medium has been particularly prolific.
Alan Brooks, an SRE contractor based in Perth says almost 90% of his current work is urban. He sources limestone rubble and recycled concrete from crushing plants often within the city itself so they can rely on quick deliveries of materials eliminating the need for stockpiling on small sites. Urban SRE is now their main business and they have developed tricks to streamline their production and keep costs down. In other parts of Australia this trend toward more urban earth wall construction is also growing.
Scott Kinsmore is a rammed earth contractor in Melbourne. He says he is building higher walls on smaller urban sites. The engineering for higher walls with more point-specific loads on small-site buildings is challenging and often requires more steel to be built within the wall structures. This can be frustrating and costly for the wall builder. Increasingly, Australian urban architects are meeting the challenges of sensible passive solar design and low embodied energy materials. While much of the current computer modelling that drives our 5 Star Energy Rating programmes is insulation-centric, some designers are using earth walling as a way to limit the embodied energy of their buildings as well as increasing their passive solar capacity.
Particles of sizes in the range of 1400m can be defined as dusts, with particles larger than 100m in size settling down near the source of formation. The total size range can be divided into three classes larger than 20m, 201m, and less than 1m these can be termed as large particles, fines and ultrafines, respectively (Leonard, 1979). The size distribution of dust generated in a crushing plant is indicated in Fig. 12.1. It should be noted that it is more difficult to separate smaller particles from the air stream as they have a greater tendency to remain in suspension (Kumar, 1987).
The amount of dust generated depends upon the type of handling and transportation equipment used. A sensitive location of dust control is generally at the conveyor transfer points, screens, crushers, bins, silos and loading and unloading points (Leonard, 1979). The dust control problem is usually restricted to dry handling of coal preparation plants.
Respirable dust is generally defined as particulate matter less than 10m in diameter according to the US Environmental Protection Agency (EPA). Respirable dust can get into the lungs of human beings and cause pneumoconiosis on prolonged exposure. The quality of air must be maintained so that the concentration of respirable dust does not exceed 2mg/m3. If the quartz content of an air sample exceeds 5%, the average concentration of respirable dust should be less than 2mg/m3 (Meyers, 1981).
The necessity for storage arises from the fact that different parts of the operation of mining and milling are performed at different rates, some being intermittent and others continuous, some being subject to frequent interruption for repair and others being essentially batch processes. Thus, unless reservoirs for material are provided between the different steps, the whole operation is rendered spasmodic and, consequently, uneconomical. Ore storage is a continuous operation that runs 24h a day and 7 days a week. The type and location of the material storage depends primarily on the feeding system. The ore storage facility is also used for blending different ore grades from various sources.
For various reasons, at most mines, ore is hoisted for only a part of each day. On the other hand, grinding and concentration circuits are most efficient when running continuously. Mine operations are more subject to unexpected interruption than mill operations, and coarse-crushing machines are more subject to clogging and breakage than fine crushers, grinding mills, and concentration equipment. Consequently, both the mine and the coarse-ore plant should have a greater hourly capacity than the fine crushing and grinding plants, and storage reservoirs should be provided between them. Ordinary mine shutdowns, expected or unexpected, will not generally exceed a 24h duration, and ordinary coarse-crushing plant repairs can be made within an equal period if a good supply of spare parts is kept on hand. Therefore, if a 24h supply of ore that has passed the coarse-crushing plant is kept in reserve ahead of the mill proper, the mill can be kept running independent of shutdowns of less than a 24h duration in the mine and coarse-crushing plant. It is wise to provide for a similar mill shutdown and, in order to do this, the reservoir between coarse-crushing plant and mill must contain at all times unfilled space capable of holding a days tonnage from the mine. This is not economically possible, however, with many of the modern very large mills; there is a trend now to design such mills with smaller storage reservoirs, often supplying less than a two-shift supply of ore, the philosophy being that storage does not do anything to the ore, and can, in some cases, has an adverse effect by allowing the ore to oxidize. Unstable sulfides must be treated with minimum delay, the worst case scenario being self-heating with its attendant production and environmental problems (Section 2.6). Wet ore cannot be exposed to extreme cold as it will freeze and become difficult to move.
Storage has the advantage of allowing blending of different ores so as to provide a consistent feed to the mill. Both tripper and shuttle conveyors can be used to blend the material into the storage reservoir. If the units shuttle back and forth along the pile, the materials are layered and mix when reclaimed. If the units form separate piles for each quality of ore, a blend can be achieved by combining the flow from selected feeders onto a reclaim conveyor.
Depending on the nature of the material treated, storage is accomplished in stockpiles, bins, or tanks. Stockpiles are often used to store coarse ore of low value outdoors. In designing stockpiles, it is merely necessary to know the angle of repose of the ore, the volume occupied by the broken ore, and the tonnage. The stockpile must be safe and stable with respect to thermal conductivity, geomechanics, drainage, dust, and any radiation emission. The shape of a stockpile can be conical or elongated. The conical shape provides the greatest capacity per unit area, thus reduces the plant footprint. Material blending from a stockpile can be achieved with any shape but the most effective blending can be achieved with elongated shape.
Although material can be reclaimed from stockpiles by front-end loaders or by bucket-wheel reclaimers, the most economical method is by the reclaim tunnel system, since it requires a minimum of manpower to operate (Dietiker, 1980). It is especially suited for blending by feeding from any combination of openings. Conical stockpiles can be reclaimed by a tunnel running through the center, with one or more feed openings discharging via gates, or feeders, onto the reclaim belt. Chain scraper reclaimers are the alternate device used, especially for the conical stock pile. The amount of reclaimable material, or the live storage, is about 2025% of the total (Figure 2.11). Elongated stockpiles are reclaimed in a similar manner, the live storage being 3035% of the total (Figure 2.12).
For continuous feeding of crushed ore to the grinding section, feed bins are used for transfer of the coarse material from belts and rail and road trucks. They are made of wood, concrete, or steel. They must be easy to fill and must allow a steady fall of the ore through to the discharge gates with no hanging up of material or opportunity for it to segregate into coarse and fine fractions. The discharge must be adequate and drawn from several alternative points if the bin is large. Flat-bottom bins cannot be emptied completely and retain a substantial tonnage of dead rock. This, however, provides a cushion to protect the bottom from wear, and such bins are easy to construct. This type of bin, however, should not be used with easily oxidized ore, which might age dangerously and mix with the fresh ore supply. Bins with sloping bottoms are better in such cases.
Pulp storage on a large scale is not as easy as dry ore storage. Conditioning tanks are used for storing suspensions of fine particles to provide time for chemical reactions to proceed. These tanks must be agitated continuously, not only to provide mixing but also to prevent settlement and choking up. Surge tanks are placed in the pulp flow-line when it is necessary to smooth out small operating variations of feed rate. Their content can be agitated by stirring, by blowing in air, or by circulation through a pump.
Recycled concrete aggregate (RCA) comes from demolition of Portland cement concrete. Given that the original concrete might have been strong or weak, dense or open graded, fresh or weathered, then the aggregates pieces can be expected to vary similarly. If the RCA comes from a central recycling plant the consistency will have been addressed, to some extent, by blending of materials from different sources. If the material is coming from an on-site crushing plant then it will reflect more directly, and more immediately, the type of concrete being crushed.
The crushing process produces agglomerations of the original concretes aggregates with adhered mortar. These agglomerations are, typically, more angular than conventional aggregates. Also the crushed concrete will produce fines from the mortar element, the amount being controlled to a large extent by the strength of the original concrete. Thus high-strength concrete will typically crush to produce very sharp, even lance-like, blade aggregates with low proportions of fines, whereas the weakest concrete may crush to produce almost the original coarse aggregates plus a large proportion of fines made of the old mortar. In the crushed mortar component, be newly exposed. The effect of this will be a slow strength gain as this cement starts hydrating either with water that has been deliberately added, or with water attracted hygroscopically from the surrounding environment. Thus RCA is, to some degree, a self-cementing material with RCA from strong concretes (those with high cement contents in the original mix) often exhibiting a higher self-cementing ability.
Crusher Plant Types: stationary crushing plant; mobile crushing plant Crusher Machine Types: jaw crusher cone crusher Impact crusher Raw Materials Applied: 1. Non-metallic mineral: limestone, river stone, marble, quartz, granite, basalt, etc., 2. Metal ore: iron ore, gold ore, copper ore, aluminum ore, manganese ore, lead and zinc ore, etc. 3. Construction waste Get A Free Quote
Crushing plant is also called crushing and screening plant, it includes sand and gravel production line, stone production line, silicon sand production line, construction aggregate production line. Our stone crusher plant are engineered to deliver unrivaled productivity in mines, quarries and civil engineering projects. We offer advanced, proven crushing and screening equipment for any size-reduction challenge. Whether youre producing several sized aggregates or crushing tons of hard rock ore, our solutions deliver the robustness and versatility you need.
Furthermore, it has been proven by many practices that the crusher plant is also particularly suitable for processing construction waste, and will lead the process of recycling construction waste in the future.
The crushing is generally divided into three steps: 1. The first step of crushing: the input size 1500 500mm, the output size 400 125mm 2. The second step of crushing: the input size 400 125mm, the output size 100 50mm 3. The third step of crushing: the input size 100 50mm, the output size 25 5mm.
We have the concept of ecological environmental protection, we promote the use of new technologies for noise reduction, dust reduction and wastewater treatment. We research and develop technologies and products for the comprehensive use of waste, and we develop a circular economy.
Aimix crushing plant mainly include statioanry crushing plant and mobile crushing plant. stationary crushing plant includes Jaw Crusher, Cone Crusher, Impact Crusher, Sand Production Line or VSI Crusher, Feeders, Screening machine and Washers, etc.
Features of Aimix Jaw Crusher: High crushing ratio, large production capacity, good shape of end products, with simple structure, reliable operation, convenient maintenance and low operating cost; Advantages of Aimix Jaw Crusher: 1. The discharge mode adjusting device with joint mode, is reliable and convenient. The adjustment range is large, which increases the flexibility of the equipment and can meet the needs of different customers. 2. The lubrication system is safe and reliable, the parts are easy to replace and the maintenance work is convenient.
Spring system for overload protection, no damage to the machine. Adopted grease seal to isolate dust and lubricants, ensure reliable operation. Standard type, medium type and short head type to choose.
Features of Aimix Cone Crushers: high quality material, reasonable structure design and regular crushed product sizes. It has features of reliable structure, high productivity, convenient fit and economical use.
Advantages of Aimix Cone Crushers: 1. reliable structure and low cost operation 2. laminated crushing shape, excellent shape of end products; 3. Its spring safety device acts as an overload protection, when iron or other strange tidal flow passes the crushing chamber, no damage will be caused to the crusher; 4. The glycerin seal is used, which isolate the dust from the lubricating oil, which guarantees reliable operation.
Attention: Hard materials can not be crushed, such as basalt, granite, river stone, etc. Normally impact crusher is used for crushing of materials that are not very hard say soft material and materials that are non-abrasive. For example limestone, coal, gypsum, seeds etc. Production capacity: 30-800 t/h; Maximum input size: 800mm; Applied in secondary or tertiary stage of crushing
Features of Aimix Impact Crusher: 1. The hammer, the impact plate and the protective plate are made of new wear-resistant materials, which are resistant to impact and wear. 2. The shape of the final products are good. With easy adjustment between the impact plate and the hammer, an effective control of the output size. 3. With reasonable hammer structure, it has the characteristics of fast dismantling and multiple transposition, which can considerably shorten the time to replace the hammer.
VSI crusher is a machine that produces high efficiency sands, which is developed after several technical improvements, based on the introduction of advanced German technology. It is the Preferred option in the field of the manufacture of artificial sands and the modeling of aggregates.
Advantages of Aimix Impact Crusher: 1. The hammer, the impact plate and the protective plate are made of new wear-resistant materials, which are resistant to impact and wear. 2. The shape of the final products are good. With easy adjustment between the impact plate and the hammer, an effective control of the output size. 3. With reasonable hammer structure, it has the characteristics of fast dismantling and multiple transposition, which can considerably shorten the time to replace the hammer.
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The term primary crusher, by definition, might embrace any type and size of crushing machine. The term implies that at least two stages of crushing are involved, but in many cases the machine which performs the function of initial crusher is the only crusher in the plant. The factors influencing the selection of a crusher for this service are much the same, regardless of how many crushing stages there are in the flowsheet; therefore, the term primary crusher, by common usage, is applied to the crusher which takes up the job of reduction where the blasting operations leave off. Selecting the right type and size of primary crusher is a problem of prime importance in the designing of a crushing plant of any nature and size. Usually this machine is the largest and most expensive single item of equipment in the plant; a mistake in the choice can only be remedied fully by replacement; and, because the entire primary crusher-house arrangement is generally tailored.to fit the crusher, such .replacement is almost always a costly procedure. While personal favouritism toward some particular type of crusher may safely be allowed to swing a close decision, it should never blind the engineer or operator to the merits of other types, nor to the limitations of his favorite. The following factors all have a more or less important bearing upon the choice of the primary crusher.
The first three of these factors will almost always be ascertainable at least to a close approximation before the matter of crusher choice is taken up. Sometimes, as when a new crushing plant, or a new primary crusher set-up, is to be installed at an existing operation the last three factors will be pre-established. Otherwise, it is sound practice to consider them as a part of the problem of crusher selection. The primary crushing setup is closely linked to the quarrying or mining operation, and it is only by careful adjustment of all equipment selections to the general plan of operation that optimum operating results may be realized.
While it is convenient to discuss the influence of these several factors separately, it is well to keep in mind that they are more or less closely interlocked, and that a change in one of them may necessitate altering one or more of the others.In addition to the factors listed there are usually a few which are peculiar to each individual problem such as labor costs and so on. Any plant design problem is an economic as well as an engineering one. We are concerned here ,chiefly with the engineering phases.
Characteristics of the material to be crushed include the geological classification of the rock, its physical structure, its chemical analysis (at least so far as abrasive constituents are concerned), and at least a qualitative evaluation of its resistance to crushing that is, whether soft, medium, hard, or very hard and tough. Frequently such information may be obtained from contiguous deposits which are being operated; sometimes the values must be arrived at by laboratory tests. It is never safe to make blanket assumptions, even on such a material as limestone, which can sometimes prove to be quite tough, as well as to contain significant amounts of abrasive silica.
Physical, or geological, structure of the deposit often has an important bearing upon selection of size or type, or both. If the deposit is thinly stratified, as, for example, many deposits of limestone are, it is safe to assume that the rock can be blasted economically into a condition for feeding a gyratory crusher of medium proportions, or, if other characteristics are suitable, a sledging roll crusher, such as the Fairmount machine. If, on the other hand, the formation is of massive character, again, some limestones are, the gyratory crusher might be ruled out in favour of the jaw crusher, unless the operation is of sufficient magnitude to warrant installation of a large size of gyratory. The proposed quarrying or mining procedure will of course have some bearing upon the size of rock to go to the crusher, regardless of its physical structure, as will be pointed out in further detail later on. If the chemical analysis of the rock discloses that substantial amounts of free silica or any other abrasive are present, crushers of the sledging roll or hammermill types are usually ruled out unless the material is extremely soft and friable. There are occasional speciality applications where such machines may be indicated for crushing abrasive materials, but from the standpoint of, economical operation their use for such service is rarely justifiable. The same restriction holds true for hard and tough materials. For such rock or ore our choice of a primary crusher is restricted to the gyratory and jaw types except, again, for the occasional specialty application where economy in maintenance may be sacrificed for other considerations such as lower first cost, or space restrictions.
The significance of this factor is so obvious that it sometimes does not receive quite as much thought as it should. From the standpoint of minimum requirement, it is of course closely tied up with product size, or crusher setting. But the primary crusher can seldom be chosen solely on the basis of capacity; it should never be selected with a view to just meeting the average capacity required to feed the rest of the crushing plant. Just how much the rated capacity of the primary crusher (at the required discharge setting) should exceed the average capacity of the plant depends upon how uniformly the crusher will be fed; or to put it more definitely, what percentage of the total operating period the crusher will operate at full rated capacity. The answer to this is not always an easy one to predetermine, as it may depend upon several details of plant design and quarry operation.
In the average quarry operation, the only surge capacity between the quarry and the primary crusher consists of whatever quantity of rock may be, at the moment, loaded in cars or trucks, and usually this is not large. For that reason, any operating delays occurring in loading, transportation or primary crushing quickly affect all three of them, with the result that the feed to the balance of the crushing plant is cut-off until the trouble is rectified. If the plant as a whole is to maintain its rated average output, these departments must be capable of making up for such interruptions, and they can only do this if they have reserve capacity over and above the average requirement.
Such interruptions to continuous production are not uncommon in the primary crusher house; they may assume serious proportions if the crusher receiving opening is not large enough for the material it is expected to handle, and the largest crushers of any type will occasionally bridge or block. Crusher capacity tables are predicated upon a continuous feed of rock of a size that will readily enter the crushing chamber; it is obvious therefore that a crusher whose rating just equals the average plant requirement would have no reserve to compensate for the conditions we have outlined. For the average quarry operation this reserve should be not less than 25 percent, and preferably about 50 percent.
Since the minimum dimension of the feed opening of a crusher determines the maximum size of lump that it can take, the choice of a primary breaker is dependent as much on the size of the feed as on the hourly tonnage. Thus a 15 in. by 24 in. jaw crusher would be suitable for a small mine hoisting 300 tons in eight hours from underground workings from which lumps larger than 14 in. are not likely to be received. A crusher of these dimensions will break 40 tons per hour to 2-in. size with a power consumption of 30 h.p. On the other hand, a 14-in. gyratory crusher, working as it should at full capacity, will crush 100 tons per hour to the same size with a power consumption of 70 h.p. ; at 40 tons per hour, it would still require about 50 h.p. The jaw crusher is evidently the more economical machine in this case, and its first cost is only about half that of the gyratory crusher.
If the capacity of the primary breaker is required to be 100 tons per hour or over, a gyratory crusher is likely to be more economical than the other type, since it costs no more than a jaw crusher of similar capacity and consumes less power. Moreover, the difference in power consumption between the two types of machine is greater in practice than in theory; this is due to the fact that, since the gyratory crusher can be choke-fed, it is easier to keep it running at maximum efficiency.
The position is different when mining is done by power-shovel. The maximum size of lump delivered to the crushing plant is much larger than from underground workings, and it is not advisable to use a bin for the storage of the ore on account of the difficulty of handling very large lumps through a bin gate. Consequently the ore is generally sent direct to a preliminary breaker which reduces it to a size suitable for feeding the normal primary breaker. The first machine is often of the jaw type, although this depends on the circumstances. Suppose, to take an instance, that the shovels were equipped with 3-yd. dippers and that 2,000 tons were being mined per day. A 48 in. by 60 in. jaw crusher is more than large enough to take the maximum size of lump that could get through the jaws of the dipper, and it would break the whole days output to 6-in. size in eight hours with a power consumption of under 200 h.p. On the other hand, a 42-in. gyratory crusher, which is the smallest that could be installed with safety, has a maximum capacity of over 5,000 tons in eight hours with a power consumption of about 275 h.p. The jaw breaker would therefore be the more economical machine. It could, if necessary, be installed near the scene of mining operations, and would be set to deliver a 6- or 8-in. product, which could be conveniently transported to the crushing section of the flotation plant where it would be fed through the coarse ore bin to the primary breaker in the ordinary way.
The choice of a primary breaker is an individual problem for every installation. The type of mining and the regularity, size, and rate atwhich the ore is delivered, are the main determining factors, but all local conditions should be taken into consideration before a decision is made.
All rock crushers can be classified as falling into two main groups. Compressive crushers that press the material until it breaks, and impact crushers using the principle of quick impacts to crush the material. Jaw crushers, gyratory crushers, and cone operate according to the compression principle. Impact crushers, in turn, utilize the impact principle.
As the name suggest, jaw crushers reduce rock and other materials between a fixed and a moving jaw. The moving jaw is mounted on a pitman that has a reciprocating motion, and the fixed jaw stays put. When the material runs between the two jaws, the jaws compress larger boulders into smaller pieces.
There are two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action.
The chewing movement, which causes compression at both material intake and discharge, gives the single toggle jaw better capacity, compared to a double toggle jaw of similar size. Metsos jaw crushers are all single toggle.
Gyratory crushers have an oscillating shaft. The material is reduced in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.
The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners.
Cone crushers resemble gyratory crushers from technological standpoint, but unlike gyratory crushers, cone crushers are popular in secondary, tertiary, and quaternary crushing stages. Sometimes, however, the grain size of the processed material is small enough by nature and the traditional primary crushing stage is not needed. In these cases, also cone crushers can carry out the first stage of the crushing process.
Cone crushers have an oscillating shaft, and 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 open side setting and closed side setting discharge opening.
The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is called interparticular crushing also.
Depending on cone crusher, setting can be adjusted in two ways. The first way is for setting adjustment to be done 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 liners wear more evenly.
To optimize operating costs and improve the product shape it is recommended that cone crushers are 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 detect the maximum and minimum levels of the material, starting and stopping the feed of material to the crusher, as needed.
Impact crushers are traditionally classified to two main types: horizontal shaft impact (HSI) crushers and vertical shaft impact (VSI) crushers. These different types of impact crushers share the crushing principle, impact, to reduce the material to smaller sizes, but features, capacities and optimal applications are far from each other.
Horizontal shaft impact (HSI) crushers are used in primary, secondary or tertiary crushing stage. HSI crushers reduce the feed material by highly intensive impacts originating in the quick rotational movement of hammers or bars fixed to the rotor. The particles produced are then further fragmentated inside the crusher as they collide against crusher chamber and each other, producing a finer, better-shaped product.
VSI crusher can be considered a stone pump that operates like a centrifugal pump. The material is fed through the center of the rotor, where it is accelerated to high speed before being discharged through openings in the rotor periphery. The material is crushed as it hits of the outer body at high speed and due to rocks colliding against each other.
Selecting optimal crushing equipment can be difficult. Luckily there are tools and software available that simplify weighting different options and help in making decisions. The backbone of all these analyzes are careful calculations that take into account the capabilities and constraints of different crushers and operational requirements.
Every crushing site and operation is different, and theoptimal results are normally obtained by combining theoretical conclusions with practical experience of different materials, operational conditions, maintenance needs, and economic aspects of various alternatives.
Below are some key issues listed according to crushing stages in brief. While defining the best technical solution for your requirements, its good to remember that many crushers are available not only as stationary but also asmobileorportableversions in case you prefer to move or transport your crusher at the production site or between sites regularly.
If you are interested in more detailed analyzes tailored just for your crushing operations, please contact Metso experts. We have practical experience of thousands of different crushing applications around the world, and we are happy to help in finding the equipment that best fits your needs.
The main purpose of a primary crusher is to reduce the material to a size that allows its transportation on a conveyor belt. In most crushing installations a jaw crusher takes care of primary crushing. Plants with very high capacities that are common in mining and less popular in aggregates production, normally use a primary gyratory crusher. When the processed material is easy to crush and not very abrasive, an impact crusher may be the best choice for primary crushing.
One of the most important characteristics of a primary crusher is its capacity for accepting feed material without bridging. A large primary crusher is, naturally, more expensive than a smaller one. Therefore, the investment cost calculations for primary crushers are compared together against the total costs of primary stages, including quarry face clearing, blasting, and drilling costs. In many cases, dump trucks transport the rock to a stationary primary crusher. This may be an expensive solution. Amortization, fuel, tires, and maintenance costs can be included when the vehicles are in high demand. In modern aggregates operations, the use of mobile primary crushers that can move alongside the rock face is, in many cases, the most economical solution.
In terms of the size of the feed opening, the client gets a better return on investment when the primary crusher is a jaw crusher. That means less drilling and blasting because the crusher accepts larger boulders. The disadvantage of this type of crusher, when high capacity is required, is the relatively small discharge width, limiting the capacity as compared with the discharge circuit of a gyratory crusher. Jaw crushers are mainly used in plants producing up to approximately 1600 t/h.
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 no rival in large plants with capacities starting from 1200 t/h and above. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Also, primary gyratories require quite a massive foundation.
The primary impact crusher offers high capacity and is designed to accept large feed sizes. The primary impact crushers are used to process from 200 t/h up to 1900 t/h and feed sizes of up to 1830 mm (71") in the largest model. Primary impact crushers are generally used in nonabrasive applications and where the production of fines is not a problem. Of all primary crushers, the impactor is the crusher that gives the best cubical product.
If the intermediate crushing is done with the purpose of producing railway ballast, the quality of the product is important. In other cases, there normally are no quality requirements, except that the product be suitable for fine crushing.
Due to their design, cone crushers are generally a more expensive investment than impactors are. However, when correctly used, a cone crusher offers lower operating costs than a conventional impact crusher. Therefore, clients crushing hard or abrasive materials are advised to install cone crushers for the final crushing and cubicising stage.
Cone crushers can in most cases also give a good cubic shape to fine grades. They can be adapted to different applications. This is an important factor, as client-specific needs often change during a crushers lifetime.
The conventional type has horizontal shaft configuration, known as HSI. The other type consists of a centrifugal crusher with vertical shaft, generally known as VSI. Impactor operation is based on the principle of rapid transfer of impact energy to the rock material. Impactors produce cubic products, and they can offer high reduction ratios as long as the feed material is not too fine. This means that in certain cases it is possible to use a single impact crusher to carry out a task normally done in several crushing stages using compressing crushers (i.e., jaw, gyratory, and/or cone crushers). Impactors are mostly used for nonabrasive materials.
Conventional horizontal-shaft impact crushers are available in various sizes and models, from high-capacity primary crushers for large limestone quarries to specially designed machines for the crushing of materials such as slag.
There are two main categories of VSI crushers machines with impact wear parts around the body and machines that use a layer of accumulated material. The first type is in many respects similar to the conventional impactor with horizontal shaft and rotor. The second type became quite popular in the past decade and is known as the Barmac crusher. The difference between a conventional impactor and a VSI of the Barmac type is that the latter offers lower operating costs, but its reduction ratio is lower also. In a Barmac VSI, the material undergoes an intense rock-on-rock crushing process. In the other crushers, most of the reduction is done by the impact of stone against metal.
Customers operating old, rebuilt, or expanded plants often have problems with the shape of the product. In these cases, the addition of a Barmac VSI in the final crushing stage offers a solution to product shape problems.
The same applies to many mobile crushing units. As the number of crushing stages is normally small with this type of plant, it is almost impossible to obtain a good product shape unless the rock is relatively soft and thus more suited for the production of cubic product. A centrifugal crusher in the final stage can help to solve the problem.
Get the maximum potential out of your size reduction process to achieve improved crushing performance and lower cost per ton. By using our unique simulation software, our Chamber Optimization experts can design an optimized crushing chamber that matches the exact conditions under which you operate.
K-series portable crushing and screening plants, which includes 7 modules and a total of 72 types, cover various mining production requirements. Compared with similar equipments of the world, the K series have more complete types and wider applications.
Coarse crushing plant, whose capacity reaches 650 t/h and the max feed size is up to 11001200 mm, includes12 types and fills the gaps of large capacity portable plant. Meanwhile, the plant not only meets quarry and coal-mining crushing, but also can be used in processing concrete and construction waste.
K-series portable crushing and screening plant, which includes 18 types, is mainly used for secondary crushing and pure screening works. With adjustable vibrating screen, it has better adaptability to different production requirements.
To solve the problem that mixed scraps lead to more handling capacity, we developed the independent joint operation portable plant. The plant can complete preliminary screening, reduce the handling capacity and increase processing capacity.
K-series portable crushing and screening plant that includes 4 types is equipped with advanced VSI vertical shaft impact crusher. The mineral products have better grain shapes, it is especially suitable for use in concrete.
The fine crushing and sand washing portable plant is specially designed for building and road-building. It integrates sand making and washing as a whole, being ideal portable plant for fine grained and coarse grained materials washing work.
Considering that cost of general portable plant is too high to small and medium-scale production line, we develop three-in-one portable plant specially. The plant meets customers' requirements for production as well as for mobility, improving equipment utilization and store value.
As a result of the great development of the basic construction and the reconstruction of the towns and the rapid rise of the high-rise buildings, the old-style buildings die out, and the waste of the construction wastes is directly buried without treatment, Then it will cause long-lasting harm to our living environment. Crusher plant can deal with construction wastes well.
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Compared with the mobile crushing plant, the stationary crushing screen plant has no tires. In view of the present situation of construction waste treatment in our country, crushing plant has strong advantages, but with the increasing maturity of construction waste disposal market, it will slowly be transformed into fixed crushing plant, that is to say, mobile crushing station is transitional equipment, and slowly will be converted into fixed type.
It is mainly used for fields like metallurgical, chemical, building material, hydro-power that needs material processing, especially for highway, railway, hydro-power with the operation of mobile stone. Customers can choose multiple configuration according to types of raw material, size and finished material requirements.
Mobile crusher plant can not only reduce the cost of transportation, but also cooperate with brick making machine to make the raw material into finished products at one time. With the increasing market demand, various types of crushing plant are needed, such as jaw mobile crushing plant, tire mobile crushing plant and other types. These plants can produce product with high quality, high crushing ratio, reliable performance.
Vibration feeder takes eccentric shaft as excitation source, gear transmission, low noise, stable operation, long life, and it can screen fine material in advance to make crusher more efficient. Adjust the gap grid design to prevent material blockage. Customers can selectively install speed-regulating motor, easy to control the feed quantity, no need for frequent start-up of the motor.
Circular vibrating screen is a kind of screening machine, which mainly produces centrifugal inertia force (excitation force) with radial variation because of the unbalanced rotation of the vibrating wheel of the exciter. Itdrives the screen box and makes the screen vibrate. The trajectory of the screen frame is elliptical. The material on the screen is thrown up by the upward movement of the screen surface, and then falls back to the screen surface after a distance. In this way, the screening is completed in the process of moving from the feed end to the discharge end. The amplitude of the vibrating screen can be adjusted by changing the weight and position of the counterweight.
As far as the counterattack crusher is concerned, the rotor rotates at high speed under the drive of the motor while working, and the material entered from the feed port is hit by the plate hammer on the rotor, which is broken by the high speed impact of the plate hammer; the broken material is hit back on the liner and broken again; later, it is discharged from the outlet. Adjusting the gap between counterattack frame and rotor frame can change the particle size and shape of material.
The material is uniformly transported into the crusher through the feeder, and after the crusher is initially broken, the closed circuit system is formed by the circular vibrating screen to realize the cyclic crushing of the material, and the material in accordance with the grain size requirements is output by the conveyor, so as to achieve the production purpose.
Before the operation, check whether the supporting equipment can run normally, such as crusher, feeder, and so on, whether the connection of these supporting equipment is loose or falling off, and whether the transmission device is abnormal. Especially the crusher, ensure that there is no residual materials in the crusher. In addition, because the working environment of the stone crushing plant is complex, the tire of the mobile crushing station is a vulnerable part, the user should also check whether the tires can work normally before carrying out the operation, so as to ensure the overall performance and normal operation.
The circuit problem of the whole machine in the operation process is a problem that the user needs to pay attention to. If there are special noises, odors or sparks in the working process, stop the operation immediately, maintain in time and never work by force. Otherwise, the whole equipment and motor may be damaged, and it is easy to cause inestimable losses to the user.
Before the stop of the crushing plant, the user must ensure that all the equipment can stop after all the materials are discharged. After the mobile crusher stops, the user should also check the circuit of the equipment, the supporting equipment and lubrication in time. For any abnormal condition, repair and maintain in time. In addition, due to the complexity of the working environment of the aggregate crushing plant, users need to clean and maintain the equipment in time after operation.