Development and Standardization of Coal Block Rough Dimensions and Allowable Deviation
In todays coal mining industry, the quality of coal mining and mining conditions are greatly improved, and norms, standards and specification of various mining products are being revised to meet the challenges proposed by the rapid development of society. As a basic technical specification for coal processing, the rough dimensions and allowable deviation of coal blocks is of great significance to the consistent performance of equipment, equipment processing and other aspects. This article mainly summarizes the development of Coal block rough dimensions allowance deviation, such as the existing international and national standards ，and their status in the whole industry, so that we can gain a deeper understanding of the importance of the standard in our industry.
In general, the permissible deviation of coal block rough dimensions focuses on the definition and regulation of the size range, regardless of the coal type, geological or process condition, or other geological conditions that may influence the block size. To ensure the commonality and uniformity of coal block rough size data, technical specifications can be used, such as ASTM International (formerly American Society for Testing and Materials), and International Committee for Weights and Measures.
The ASTM D6388-15 Standard Specification for Coal Sampling and Preparation requires that the coal block be cut and screened to 40 by 40 millimeters (1.57 by 1.57 inches) so that the weight of the sample is not less than 0.45 kilograms (1.0 pounds). The allowable deviation shall be in line with 6%. According to the standard, the sample size and screening size of the coal block should be stable through thick, thin and even, which will assure accuracy and result in fewer errors.
International Organization for Standardization (ISO) has published several standards relevant to coal quality, ISO 15853:2011 Coal Mining and Preparation—Sampling and Analytical Procedures for Coal and Coke. The standard stipulates that the approximate dimensions of the coal sample shall be 0.35 to 0.70 kg, measuring at a maximum of 8 cm by 8 cm by 8cm, with no more than 6% acceptance deviation.The International Committee for Weights and Measures (CIM) stipulates in its S1-2004 standard for operating specifications for the determination of coal properties that the block size does not exceed 8cm by 8cm by 8cm, and the sampling error is within 10%.
In China, GB/T 4701-2018 Coal quality sampling and preparation methods describes the technical requirements of sampling and preparation methods of coal samples, and stipulates the requirements of block size standard. The coal block rough dimensions shall not exceed 20 cm×20cm×25cm in general coal, 40 cm×40cm×50cm in low-temperature coal, and 40 cm×25cm×50cm in high-temperature solid coal. The sample size of coal blocks should not be less than 1 kg, and the allowable deviation rate should not exceed 6%.
In summary, the development of coal block rough dimensions and allowable deviation norms and regulations must be kept pace with the technological advancement so that they can be applicable to various processes and international situations. Such developments and standardization require rigorous testing of samples, comprehensive analyses and comparative studies to fulfill their ultimate objective of reaching internationally accepted standards. For the benefit of both users and manufacturers, coal block rough dimension and allowable deviation specifications should be listed in the manuals of each major European training institution, and in the China State Quality Supervision and Inspection Center for Coal Mining Machinery. The recommended standard should not exceed 6%, and should be easily understood in a way that helps industry users monitor these devices.
