What is the purpose of coal washing?

Coal washing is an essential process in the deep processing of coal. Coal extracted directly from mines is known as raw coal, and this raw coal contains many impurities during extraction. Moreover, the quality of coal varies, with coal having low ash content mixed together with coal having high ash content. Coal washing is an industrial process used to remove impurities from raw coal, or to separate high-quality coal from low-quality coal. The products obtained after the coal washing process are generally classified into gangue, medium-grade coal, grade B refined coal, and grade A refined coal. The coal that results from this process is usually referred to as refined coal. Coal washing helps to reduce transportation costs and improve the efficiency of coal utilization. Refined coal can be used as a fuel source, while refined bituminous coal is primarily used for coking; it undergoes processes such as sulfur removal and impurity elimination to meet the standards required for coking. The quality of coal washing can be tested for various parameters using the following equipment: microcomputer-based ash fusion point tester, automatic hydrogen analyzer, industrial analyzer, Oya swelling degree tester, coal ignition point tester, microcomputer-based calorimeter, activated carbon analyzer, coal caking index tester, microcomputer-based binder index tester, and rapid ashing furnace. Coal washing makes use of the different physical and physico-chemical properties of coal compared to other substances; it involves using 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-based 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 system composed of many operating systems.

The medium used in jig coal washing is water or air; in some cases, suspensions are also used. Currently, hydraulic jigging is the most widely used method in coal washing. 　　 A jig is a device that uses 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.

Simply put, the purpose of coal washing is to reduce the ash content of coal in order to meet the requirements for coking. Currently, the main methods for coal washing are jigging and cyclones; both processes rely on water. Heavy media cyclones for coal sorting require iron media powder, and the pipes used in coal washing need to be wear-resistant.

The purpose of coal washing is to remove substances such as ash, coal gangue, and slime from the raw coal, thereby transforming it into refined coal with varying calorific values. It involves separating various components present in the raw coal, including refined coal, thermal coal, coal gangue, ash, and slime.