Introduction
China is one of the world’s leading producers of coal, and it is a vital resource for the country’s economy. The Chinese coal industry has traditionally employed several coal classification systems, which are mainly used for the evaluation of coal quality, for the homogenization of the supply of coal for the industrial production of coal and for the identification of the hazards during mining operations. Two of the most popular methods in use in China today are the Coal Seam Classification System (CCS) and the National Coal Quality Grading System (NQGS).
Coal Seam Classification System (CCS)
The Coal Seam Classification System classifies coal according to its physical and chemical properties, as well as its energy content, ash content and volatile matter. The CCS is based on the analysis of a sample of coal from a specific coalfield and its general characteristics. The CCS is widely used in the coal evaluation process, as it is able to provide a general estimation of the quality of coal before its actual extraction.
The CCS system consists of five stages, based on the analysis of a sample of coal. The first stage is a general assessment of the sample, which includes the determination of its overall physical and chemical properties. The sample is then further examined in the second stage, which evaluates the coal’s energy content and ash content. Other parameters, such as volatile matter and sulphur content are also evaluated in the second stage. The third stage evaluates the coal’s volume and total moisture content, while the fourth stage evaluates the coal’s combustion characteristics and surface properties. The fifth and final stage of the CCS operation seeks to assess the relative abundance of the coal within the coalfield.
National Coal Quality Grading System (NQGS)
The National Coal Quality Grading System (NQGS) evaluates coal according to its energy content, combustion properties and ash content. The NQGS is designed to help with the supply of coal for industrial production and as such is used extensively in the coal production industry.
The NQGS assigns each coal sample an A,B,C or D grade that corresponds to its overall energy content and combustion properties. A-grade coal is the highest grade and contains the most energy, followed by B-grade, C-grade and D-grade, which contain decreasing amounts of energy. Additionally, each coal sample is also assigned an additional index which indicates the max ash content within the sample. This ash content index is used to ensure that coal of a certain grade is suitable for industrial use.
Conclusion
China is one of the world’s largest coal producers, and the classification of coal is a crucial process for the country’s industry. The two main coal classification systems used today are the Coal Seam Classification System (CCS) and the National Coal Quality Grading System (NQGS).The CCS classifies coal according to its physical and chemical properties, whereas the NQGS assigns each coal sample an energy content and ash content grade. Both systems are widely used in the Chinese coal industry, as they are able to provide a general assessment of the coal quality before it is extracted.
