Crushing is a process in which minerals are transformed into a product with desired dimensions in various stages, including crushing and grinding, so that not only its transportation to the next stages is easier, but also achieve the degree of freedom which is the most important goal of its reduction. allocates itself Therefore, design, selection of the appropriate circuit, optimization and control are among the parameters related to the crushing circuit, which by considering them can not only increase the mechanical efficiency, but also prepare a more favorable product for the refining stages.
Crushing operations in industries It is widely used in various industries such as mining, construction, chemical, material engineering, agriculture, food industry, etc. Although the purpose of shrinking in these industries is similar in many aspects, it is also different in many aspects. This difference also exists in the laboratory and industry.
segmentation of rational equipment
There is a wide range of crushing equipment in the world. The main reason for the lack of standardization of the use of this equipment is the variety of materials under grinding, the quality of the product required, the limitation of the theory of grinding and the economic information necessary for investment and operational costs in different industries. But for the ease of choosing and using these equipments, it is necessary to classify them. Shredding equipment can be classified from different aspects such as input load size, product size, how to apply force and failure mechanism, shredding environment, use in the circuit, etc.
Crushed Equipment
Crushing equipment on an industrial scale
Stone crushers and mills that are used on an industrial scale are presented below
🔰Primary stone crushers< br>The first step is crushing large and hard pieces of stone coming out of the mine, crushing and reducing the dimensions. Ores such as tin and gold placers and sand ores usually do not need primary crusher. Stone crushing operations on an industrial scale are performed by jaw crushers, gyratory, impact, self-loading, toothed roller, low-speed toothed and coal crushers. A- jaw crusher< br>Jaw crushers have two jaws, one fixed and the other movable, which are located at certain angles relative to each other. The material input to the crusher is pressed and crushed alternately between phases. These crushers are divided into three groups, Blake 1, Dodge 2, and Universal 3, based on how the movable jaw is hinged. In Blake, Dodge, and Universal, the hinge is located at the top, bottom, and middle of the jaw, respectively. Among the different jaw crusher models, the Blake type is the most widely used. Dodge type is used only in the laboratory to prepare a product with uniform grain size. The jaws are made of wear-resistant steel. Both jaws may be flat, or the fixed jaw may be flat and the movable jaw may be convex. The surface of both jaws may be smooth or wavy. Blake crusher is made in two types of simple and double arm. The double arm type is used for hard stones and the simple arm type is used for low hardness stones. These types of stone crushers are used as primary stone crushers in factories whose capacity is less than 1000 tons per hour.
B- Gyratory crusher
The gyratory crusher consists of a fixed cone-shaped body (cup) and an intermediate crushing core that has a gyratory movement. The desired materials are crushed in the distance between the fixed body and the moving core. During the time that in one part of the space inside the crusher, the moving core is approaching the body, the materials are crushed in that part, and in the same period of time, in the opposite part, the distance between the fixed body and the moving core is increasing. And the materials in that part gradually move to the lower parts and fill the available space. In this way, the rock crushing operation is done continuously and the force required for it is uniform.
This rock crusher, unlike the jaw, does not need a feeder and it can be directly fertilized by large mining trucks from several directions. This stone crusher is made in three models, dependent, suspended and fixed axis. Technical problems have limited the construction of the fixed axis model, especially in large dimensions, for this reason, the first two models are more common.
T-Feeder breaker
Feeder breaker consists of three main components: feeder, crusher and rail for moving the crusher. The material is continuously fed from the mine to the loader by means of a funnel and transferred to the crusher. After crushing, the materials are directed to the material transfer system. In this stone crusher, due to the special structure of the crusher, only coarse-grained materials and fine-grained materials pass through it. In this way, in addition to reducing energy consumption, the production of soft drinks is also prevented. The most common use of this crusher is in underground coal mines.
3- Low speed sizers
This crusher consists of two cylinders with very large teeth that rotate in opposite directions at low speed. The material moves down due to its own weight and is crushed between the teeth. In this crusher, coarse grain materials are always crushed and fine grain materials pass through it, which reduces energy consumption and reduces the production of soft materials. Due to the need for space and low height, this type of stone crusher is very suitable for underground applications, especially for coal. Stone moisture has no effect on the performance of this type of crusher, so it can be used for clay materials as well. This stone crusher has the ability to crush large pieces of stone, and its only limitation is to crush stones with a compressive strength of less than 200 MPa
C- Geared roller stone crusher
This stone crusher is made in single and double roller models and is used as a primary stone crusher for crushing the output of coal mines. In the single-roll crusher type, two series of teeth are installed on the roller. A series of long teeth that are responsible for crushing large parts and transferring the incoming load into the crushing chamber, and smaller teeth are installed in between them, whose job is to reduce the size of the incoming load to the dimensions of the product. The largest acceptable dimension for these breakers is relatively one meter and its output reaches 40 mm. The double-roller crusher has two toothed rollers and is more flexible than the single-roller samples due to its adjustable distance and produces less smoothness. The distance between the rollers can be adjusted during work and reaches 127 mm.
C- Coal rotary crusher
This crusher is similar to a rotary crusher and includes a mesh cylinder and a It is the outer shell. The cylinder has a lifting mesh and the material is carried upwards by it, and from there it falls due to its own weight and is crushed. The crushed material passes through the nets and comes out of the crusher. The diameter of the cylinder of these crushers varies from 1.8 to 3.6 and its length is 1.5 to 2.5 times its diameter. Its rotation speed is 12 to 18 revolutions per minute. The diameter of the nets is chosen based on the dimensions of the product. The capacity of these crushers for coal is about 1500 tons per hour and they are used for selective crushing of coal. Coal is a loose material and crumbles easily when it falls, while impurity materials such as sandstone, silt and shale are resistant and crumble more slowly. These coarse grain impurities are transferred to the outside of the crusher, so it is also considered a pre-concentration stage.