In the processing plant production, crushing ore preparation work is necessary in conventional grinding process of crushing, crushing 12% to 25% of the grinding energy consumption. Larger scale beneficiation plant, reduce grinding feed size of The economic benefits are also more significant. According to research, for the concentrating plant with a scale of 10 million tons, when the final product size of the crushed ore is reduced from 20mm to 12mm, although the crushing capacity is reduced by 1/3, the ball mill has Processing capacity can be increased by 16% [1]. It can be seen that in the crushing system, the particle size of the crushed ore products is minimized, and the crushing effect is fully exerted to improve the processing capacity of the grinding. The “multi-breaking and less grinding†is the energy saving and consumption reduction of the ore dressing plant, reducing the cost and improving the economic benefits of the enterprise. One of the effective measures. Therefore, in the design of the concentrator, the determination of the crushing process and the choice of equipment are reasonable, which directly affects the economic and technical indicators of the concentrator.
2. Development status of the crushing plant
The crushing process commonly used in the plant is divided into two stages of crushing process and three sections of crushing process. The two-stage crushing process is divided into two forms: open circuit and two segments and one closed circuit. The crushed product obtained by the two-stage open-circuit crushing process has a coarse particle size and is only used in a simple small-scale plant. The first stage may not be pre-screened. When the original ore size is not large, and the second section adopts a crusher with a relatively large crushing , a two-stage closed-circuit crushing process is adopted.
The basic types of the three-stage crushing process are: three-stage open circuit and three-stage one closed circuit. The three-stage and one-off crushing process has been widely used as a preparation for grinding. Whether it is underground or open-pit mining ore, as long as the raw ore is not high in mud, it can be effectively adapted. Therefore, concentrators of different scales can be used.
Compared with the three-stage and one-closed process, the three-stage open-circuit crushing process has a coarser particle size, but it can simplify the equipment configuration of the crushing plant and save capital investment. Therefore, this process can be used when the grinding ore particle size requirements are not strict and the grinding of the grinding section is carried out by rod grinding, as well as the treatment of muddy ore with high water content and terrain limitation. [2] .
At present, the most commonly used Crushing Equipment in the concentrator, the coarse crushing is generally a rotary crusher or a Jaw Crusher . The medium crushing is generally a standard cone crusher and a medium cone crusher . The fine crushing is generally a short head cone crusher and a double roll. For crushers, there are also counter-attack or hammer crushers . The latter three crushers are only suitable for crushing medium hard soft or brittle ore, and the disadvantages are obvious. The roller liner of the double roll crusher is easy to wear, requires frequent maintenance, and has low production capacity; the impact crusher hammer and The counterattack is easy to wear and needs to be replaced frequently.
3. The problem of designing the crushing process of the plant
At present, the main problems in the production practice of crushing equipment in the concentrator are as follows: First, the processing capacity of coarse, medium and fine crushing equipment is not matched; second, the mining ore mining granularity is large, which is incompatible with the maximum feeding size allowed by the coarse crushing equipment. Generally, the mining ore has a large grain size. In the design, it is difficult to inspect the processing volume, and the total crushing ratio and the coordination of the selection of the front and rear equipments increase the design difficulty [3]. In the design of the concentrator, it is difficult to coordinate the relationship between the treatment volume and the fracture ratio between the sections. It is often the case that the crushing ratio is better than the allocation, but the selected equipment handling capacity does not match. The only solution is to increase the equipment configuration, but this will not only increase the equipment investment in infrastructure investment, but also increase the mineral processing operation. cost. The development and application of large crushing ratio and ultra-fine crushing equipment have solved this problem better.
4. Introduction to new crushing equipment
4.1 Super wear-resistant external jaw crusher
The super wear-resistant external jaw crusher is a new generation of high-efficiency, energy-saving and low-wear crushing equipment developed by the North Mine Institute. This product has fundamentally changed the traditional design of the traditional compound pendulum jaw crusher with the connecting rod in the four-bar linkage mechanism for more than 100 years. The movement of the eccentric shaft is transmitted to the outer moving jaw through the side plate. The new design structure improves the kinematics and dynamics of the equipment, which improves equipment performance. The device has now formed two series of pa low and pd large crush ratio.
Pa low series super wear-resistant external jaw crusher is a widely used medium crushing and coarse crushing equipment, especially suitable for underground and mobile crushing units and other space-constrained occasions. Its characteristics are as follows: low profile The feeding height is 25% to 30% lower than that of the conventional model, which saves installation space and reduces the construction amount of the diverticulum; the liner has a long service life, the moving trajectory is ideal, the component of the wear direction is small, and the lining wears. Significantly reduced, the life expectancy is increased by at least 3 to 5 times. Compared with the traditional compound pendulum jaw crusher of the same specification, a larger crushing stroke can be obtained with a smaller eccentricity, the spindle speed is high, the equipment is energy-saving, and the single machine energy saving 15 %~30%, the system energy saving is more than double; the adjustment range of the discharge port is large, and the crushing ratio varies greatly, which can meet the needs of different users.
Pd large crushing ratio series super-pole wear-resistant external moving jaw crusher is a widely used coarse, medium and fine crushing equipment, especially suitable for crushing hard materials and requiring large crushing ratio. The characteristics are as follows: large crushing ratio Up to 15, in some cases, the two ends can be broken instead of the traditional three-stage crushing or one-stage crushing instead of the traditional two-stage crushing. Other features are the same as the pa-type jaw crusher.
4.2 double action jaw crusher
Shenyang Gold Institute developed a double-acting jaw crusher, which uses a double-acting jaw, negative rake angle, deep crushing chamber, variable nip angle, hanging low, high speed, adjustable integrated overload protection and a variety of new lining Advanced technical measures such as board, after continuous development and improvement, have now formed a series of products, including sep250×400, sx 300×500, sxa300 × 400, sxi 50×500. Sx400×700. The gold mines in Liaoning, Shandong, Gansu and other places first adopted the sxa 300×400 double-action jaw crusher [4]. The production practice proves that the machine is 25% more energy efficient than the similar single-action jaw crusher. The life expectancy is increased by 2-3 times, the crushing ratio can reach 1 o-25, and the capacity is increased by 6 o % to 130% compared with the single-action jaw crusher. And a section of crushing can be used instead of two sections of closed circuit crushing to simplify the crushing process.
4.3 Roller Screen Crusher
ThyssenKrupp Mining Material Handling Technologies is a world leader in stand-alone and complete equipment for the mineral processing industry. The company's roll-type screening crusher has a production capacity of 50t/hour up to 5000t/hour, and the maximum feed size of the crushed material is about 1700mm. Screening can roll crusher crushing rocks and the viscous medium hard and soft materials such as brown coal, minerals, clays, marl, limestone and similar materials.
The crushing ratio of the roller screening crusher can reach 4:1 or even 6:1. The size of the product after crushing by the roller screening crusher is clear, the rate of exceeding the standard is low, suitable for primary or secondary crushing, and the final product size can be Less than 50mm. The crusher's power consumption rate, wear rate and fine particle content of the finished product are relatively low compared with other crushers. It can handle large feed sizes, generate less dust, and has low operating cost and high efficiency.
4.4 psh type double cavity gyratory crusher
The characteristic of the psh double-cavity gyratory crusher produced by Beijing Haiying Mine Engineering Equipment Co., Ltd. is that the middle crushing wheel is an eccentric rotating structure, and the materials in the two crushing chambers on both sides can be suspended by the eccentric rotating roller. The movement is segmented, and in turn, it is broken under the combined action of compression, grinding and splitting. The crushing work alternates between the two chambers, and the product is continuously discharged from the two discharge ports. The two high-efficiency crushing chambers are designed with the new dynamic meshing concept. The bottom of the cavity has a large-angle non-blocking discharge opening, which results in high crushing efficiency and improves the production capacity of the whole machine. This type of equipment is advanced, the crushing ratio is 12-50, which can achieve the goal of multiple crushing and less grinding; the production efficiency is 2-3 times of the equivalent capacity cone crusher; the energy consumption is reduced by more than 50% compared with the traditional model, and the crushing efficiency is improved. 10%-20%, at the same time strong and durable, easy to operate and maintain.
4.5 pp rotary disc crusher
The machine is modeled after the rexord machine of the United States by the Shenyang Heavy Machinery Factory. It is based on the pyd600, pyd900 spring cone crusher: φ6oo, φ900 ultra-fine broken disc crusher, from Shenyang Heavy Machinery Factory, Zhaoyuan Gold Manufactured by the main machinery factory, the parallel crushing zone is formed between the crusher wall and the rolling mill, which realizes the intergranular crushing, thereby greatly reducing the grain size of the ore and increasing the crushing ratio [5]. Since the feeding part sets up a separate driving rotary hopper, it ensures uniform feeding, prevents instantaneous load shock and reduces power consumption. The equipment has been widely used in small and medium-sized concentrators represented by silkworms, and the energy consumption is reduced by about 25%.
5, crushing process optimization practice
Due to the development and application of new equipment, the traditional thinking mode has been gradually changed in the determination of the crushing process and the selection of crushing equipment. Some new designs and the transformation of old processes have become a reality. These reforms often have less investment. It has a quick effect and brings social and economic benefits to the company.
5.1 Practice of crushing technology transformation in a small plant in Baotou, Inner Mongolia
The primary processing capacity of the first concentrator was 100 t/d. The plant has transformed the original traditional crushing process, applying a new type of fine crusher jaw crusher and ultra-fine crushing disc crusher, using two-stage open circuit, pre-crushing and screening process, as shown in Figure 1. One section uses pex250×750 jaw crusher, when the discharge port is 12-14mm, the second section uses φ600 ultra-fine rotary disc crusher, in which the process uses szz: 900×1800 self-centering Vibrating Screen for pre-screening, Prevent the blockage of the discharge port of the f 600 ultra-fine rotary disc crusher. Production practice proves that this crushing process has small particle size, uniform equipment load and processing capacity of 150-200 t/d.
The original processing capacity of the second concentrator was 100 t/d. In order to further reduce the particle size of the crushed product, the plant has modified the crushing process, as shown in Figure 2. One section uses ordinary pef400×600 jaw crusher, the product size is one 68mm, the coarsely crushed product is pre-inspected and screened. The 2ya1200×3600 double-layer vibrating screen is selected as the pre-inspection screening, the first sieve diameter It is 38 mm, the second layer is 10 mm, and it produces three products of coarse, medium and fine. The coarse grain is given to the kue-ken (12 × 24 ) 深 deep cavity crusher, which will break the oversized particles and the middle granules. The product is merged into the φ900 ultra-fine broken disc crusher, which is broken and returned to the vibrating screen to form a closed circuit. Production practice proves that this crushing process product has fine grain size, can reduce over-grinding, save energy consumption, and has large processing capacity, up to 400 t/d.
5.2 Other typical crushing processes
A section of open-circuit crushing process generally adopts double-action jaw crusher. The biggest advantage of this machine is that the crushing ratio is large, and the crushing ratio can reach 1o~25. Therefore, one section can be used instead of two sections to closed-circuit crushing. The crushing process is simplified, and the capital investment is greatly saved. The crushing process is adopted by the concentrating plants such as the Zhangping Graphite Mine and the Qingyuan Gold Mine in Liaoning.
6, the conclusion
The determination of the crushing process and the selection of the crushing equipment should fully handle the following three aspects: First, the coordination problem between the processing capacity and the crushing ratio between the crushing equipments should be solved to meet the process requirements to the greatest extent; Try to simplify the process structure and save capital investment; the third is to embody the principle of “breaking more and less grindingâ€, creating good external conditions for grinding, reducing energy consumption and improving economic efficiency. The development and application of large crushing ratio and ultra-fine crushing equipment, as well as the introduction of foreign advanced equipment, make the structure of the crushing process more reasonable and diversified. Significant results have been achieved in the practice of plant selection process reform.
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