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Coal processing, gangue treatment, and the transportation of materials and equipment constitute the surface system of a mine. The surface coal processing system consists of main stages such as coal reception, screening, crushing, sorting, storage, and loading. It is the main entity for production at the mine surface. Coal reception involves installing coal bins of a certain capacity near the shaft entrance to receive the coal lifted from underground to the surface, thereby ensuring balanced and continuous production both above and below the shaft entrance. Screening is the process of separating mixtures with particles of different sizes into various size categories using a sieve with holes. The machine used for sorting is called a screener or sieve. In coal preparation plants, screening operations are widely used in the preparation and processing of raw coal. Based on the screening method, it is divided into dry screening and wet screening. Crushing is the process of breaking large pieces of material into smaller particles. A machine used for crushing is called a crusher. The main requirements for crushing operations in coal preparation plants are as follows: 1) Meeting the requirements of the particles to be processed ； The size range of coal particles that can be processed by selected machinery is limited; larger pieces exceeding this range must be crushed before they can be washed and processed. 2) Some coal lumps are actually mixed coal containing gangue; in order to separate the high-quality coal from this mixture, it is necessary to crush them into smaller particles. 3) To meet the customer’s requirements regarding particle size, the selected product or coal lumps are ground to a specific particle size. Mechanical methods are primarily used for material grinding, including compression, splitting, breaking, crushing, and grinding. Coal washing involves using the different physical and physico-chemical properties of coal compared to other substances, and employing mechanical methods in coal washing plants to remove impurities mixed in with the raw coal, thereby separating it into products of varying quality and specifications to meet the needs of different customers. Based on the location relative to the coal mine, coal preparation plants can be classified into: mine-based coal preparation plants, group-mine coal preparation plants, central coal preparation plants, and user-specific coal preparation plants ； Most of the coal washing plants in our country are mine-based coal washing plants. A modern coal washing plant is a continuous mechanical processing process consisting of many operations. Jig coal sorting is a process of separating coal particles based on differences in their density, carried out in a vertically pulsating medium. The medium used in jig coal washing is water or air; in some cases, suspensions are also used. Hydraulic jigging is the most commonly used method in coal washing. A jig is a device that utilizes the principle of jig sorting to separate the feed material into products such as clean coal, medium coal, and gangue coal, based on their density. Heavy medium coal separation is a method of coal separation that utilizes a medium with a density greater than 1 g/cm3, and it relies on the differences in particle density for separation; this process is known as heavy medium coal separation. The heavy media used in coal washing fall into two categories: heavy liquids and heavy flotation slurries. The main advantage of heavy medium coal separation is its high separation efficiency compared to other coal separation methods ； The range of sizes that can be processed is wide; the feed particles for the separator range from 1000 to 6 mm, while those for the cyclone range from 80 to 0.15 mm. Production control can be easily automated. The disadvantages of heavy medium coal washing are complex production processes, high production costs, rapid equipment wear, and substantial maintenance requirements. Heavy medium coal separation generally involves feeding the coal in stages. Bituminous coal sorting is generally carried out using a heavy medium separator under the action of gravity ； The separation of slime coal is carried out using a heavy media cyclone under the action of centrifugal force. Coal storage silo: A silo with a certain capacity that is designed to address any imbalances between production, transportation, and sales, thereby ensuring normal and balanced operations in the mine and transportation sectors. It receives the coal that has been produced, ensuring that it can be exported smoothly and reach the final loading stage. Loading: includes loading (onto ships), cranes, and measurement. http://hljbest.com/img/gongyitu1.jpg Flow chart of coal washing plant 1 http://hljbest.com/img/gongyitu.jpg Flow chart of coal washing plant 2