The Source of Ash in Coal and Its Determination Significance

Sources of ash in coal and significance of determination

(1) Sources of ash in coal Ash in coal is not an inherent component of coal, but the residue left after all combustible materials in coal are completely burned and minerals in coal undergo a series of complex reactions such as decomposition and combination at a certain temperature. Ash is often called ash yield.

There are three sources of minerals in coal:

① Primary minerals. Inorganic elements contained in coal-forming plants, generally in low content.

② Secondary minerals. Minerals mixed in from the outside or associated with coal during the coal-forming process, generally in low content.

③ Extrinsic minerals. Minerals mixed in during coal mining and processing.
Primary minerals and secondary minerals are collectively referred to as intrinsic minerals, both of which are usually difficult to remove by coal preparation methods. Extrinsic minerals can be removed by coal preparation methods.

(2) Significance of determination Ash is a substance that reduces the quality of coal and has a harmful effect in various occasions of coal processing and utilization. Therefore, the determination of coal ash is of great significance for the correct evaluation of coal quality and processing and utilization.

① Ash is the main indicator for coal trade pricing.
② In the coal washing process, ash content is an indicator for evaluating the quality of clean coal and washing efficiency.
③ In the coking process, ash content is an important indicator for evaluating the quality of coke.
④ In boiler combustion, the thermal efficiency of the boiler is calculated based on the ash content, taking into account the slag removal workload, etc.
⑤ In coal quality research, the calorific value and mineral content of coal can be roughly calculated based on the ash content.

China's national standard (GB/T212) stipulates that the determination of ash content in coal includes two methods - slow ash method and fast ash method (including method A and method B). Among them, the slow ash method is the arbitration method. (end)