Crushing and screening machinery is the necessary construction machinery for industrial and mining enterprises.
Their main function is to crush and classify large pieces of raw materials into small pieces suitable for production or use, and to exclude materials that do not meet the specification requirements, thus improving the utilization rate of materials and product quality and reducing production costs. Different kinds of crushers differ in their discharge size, while the screening work is to classify the materials after crushing and extract the materials that meet the requirements.
For example, the mechanism sand industry, it is the processing and production of various specifications of gravel and sand machinery and equipment, its role is to crush large pieces of rock, screening and grading, forming different sizes of gravel, gravel, etc., widely used in the construction of highways, construction, water conservancy and mining industry.
The following will discuss the importance of crusher and screening work in terms of discharge size and the need for screening work.
A. Introduction to the role and types of crushers
1. crushing machines, according to the crushing mode and structural characteristics, crushers are jaw, cone, roller, hammer;
screening machinery, screening machinery according to the work mechanism movement or not can be divided into two categories of immobile and movable;
2. Each type of crusher has its unique working principle and scope of application, and different crusher discharge size is also different. In the production process, the correct choice of crusher type and setting a reasonable discharge size can greatly improve the production efficiency and product quality. For example, for jaw crushers, the discharge size can be set to about 10-300mm in general, while for hammer crushers, the discharge size range is generally larger and can be adjusted according to actual needs.
3. Different size of crushing products are divided into: coarse crushing, medium crushing, fine crushing and Grinding;
Crushing operations by product size(Table 1-1)
Crusher inlet and outlet comparison table
B. Importance of discharge size
The discharge size of a crusher is related to the category to which it belongs. As shown in Table 1-1, primary crushers are usually used for coarse crushing, and their discharge size is usually above 50 mm; intermediate crushers are usually used for medium crushing, and their discharge size is from 6 to 25 mm; while advanced crushers are used for fine crushing, and their discharge size can reach a few millimeters or less.
Different crusher categories correspond to different discharge sizes, which can meet the material requirements of different industries, such as the construction industry, which requires aggregates that meet certain specifications.
C. Aggregate size and usage
Coarse sand: grain size greater than 2.0 mm, generally 5-20 mm, mainly used in the preparation of concrete and mortar Preparation.
Medium sand: particle size of 0.5-2.0 mm, mainly used for concrete, mortar, road and sidewalk paving.
Fine sand: grain size less than 0.5 mm, generally 0-5 mm, mainly used for mortar preparation, laying floor tiles, plastering walls, etc.
Stone powder: particle size less than 0.5 mm, generally 0-2 mm, mainly used in the preparation of concrete and mortar Preparation, can also be used for paving the ground.
Gravel: particle size of 2-5 mm, mainly used for pavement, sidewalk, square, etc.
Flake stone: the particle size is 10-30mm, mainly used for pavement, sidewalk, square, etc.
Coarse gravel: particle size of 20-40 mm or 40-80 mm, mainly used for concrete preparation, pavement paving of base and subgrade, masonry wall, etc.
Medium gravel: the grain size is 5-20mm, mainly used for concrete middle layer, road middle layer, sidewalk, Fitness walkway, etc.
It should be noted that different construction projects require different sizes and uses of aggregates, and the specific selection needs to be considered in conjunction with the specific project requirements. At the same time, when using sand and gravel aggregates, it is also necessary to pay attention to whether their quality and specifications meet the relevant standard requirements to ensure project quality and safety.
D. A brief analysis of the actual situation of the crusher crushing materials
In actual production, the discharge size of the material crushed by the crusher often does not fully meet the production requirements. Therefore, the crushed material needs to be screened in order to achieve the required discharge size. Screening work can be done by screening equipment, such as vibrating screen, airflow screen, etc.
Why the size of the material crushed by the crusher is often not fully compliant with the production requirements?
The following is an example of a jaw crusher;
The reason why the jaw crusher discharges mixed material is mainly due to the structure and operation of the crushing chamber.
The crushing chamber of the jaw crusher consists of two moving steel plates, the stone is crushed by being sandwiched between the plates, one of which is fixed and immobile, while the other is moved by a movable mechanism.
During the crushing process, the stone will be sandwiched between two steel plates and crushed back and forth, which will lead to some of the stone being repeatedly ground and rotated between the steel plates, eventually forming a mixture. At the same time, the structure and operation of the crushing chamber of the jaw crusher also determines the location and shape of the discharge opening, which makes some mixed materials not easy to be discharged from the discharge opening, thus further increasing the probability of the discharge being mixed materials.
In order to reduce the proportion of mixed material in the discharge of the jaw crusher as much as possible, the crushing effect can be improved by adjusting the structure of the crushing chamber, optimizing the crushing process and replacing the suitable crushing tooth plate to reduce the generation of mixed material. At the same time, screening equipment such as vibrating screen can be added to screen the discharge material, which can also effectively reduce the proportion of mixed material and improve the quality of the crusher’s discharge material.
E. The need for screening work
Definition and role of screening work
1. Screening work is carried out after the material has been crushed. It can divide the material into different levels, exclude the material that does not meet the specification requirements, improve the utilization rate of the material, and thus reduce the cost. Screening work can also prevent materials of different sizes from being mixed together to cause production failures. In addition, screening work can also improve the quality of products and enhance the market competitiveness of products.
2. Screening work is widely used in mining, construction, manufacturing and other industries. In the mining industry, the screening work is mainly used for the classification and removal of impurities of ores; in the construction industry, the screening work is mainly used for the classification and removal of impurities of aggregates and the preparation of concrete; in the manufacturing industry, the screening work is mainly used for the classification and removal of impurities of parts.
3. The types and characteristics of screening equipment also vary with the industry. Commonly used screening equipment includes circular vibrating screen, linear vibrating screen, high frequency vibrating screen and so on. Circular vibrating screen has the advantages of small inclination angle of screen surface and good screening effect; linear vibrating screen is suitable for grading finer materials with high screening efficiency; while high frequency vibrating screen is mainly suitable for materials with high grading precision requirements.
4. In the actual production, the necessity of screening work cannot be ignored. Screening work can exclude materials that do not meet the specifications, improve the utilization rate of materials and product quality, reduce production costs, thus creating greater economic benefits for enterprises. At the same time, the reasonable selection and use of crushing and screening equipment also helps to protect the environment and reduce the production of waste, in line with the modern industrial development of sustainable development requirements.
In conclusion, crushers and screening work are indispensable machinery and process links for modern industrial production. They play an important role in different industries to meet the requirements of different industries for materials, improve production efficiency and product quality, and reduce production costs. With the continuous development of science and technology, screening equipment and technology is also constantly updated, tending to automation and intelligence, which will bring greater benefits and contributions to the production of different industries.