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Through process optimization, we have achieved high-precision indexing and measurement using the existing general-purpose equipment in our factory. The quality of parts processed is on par with that of components manufactured in Germany using CNC machines, which has not only yielded good economic benefits but also resolved the issue of local production of components for users. In particular, by applying new manufacturing methods such as rotating fixtures and corner compensation measurement, we have developed a complete set of techniques for producing high-quality products on conventional machine tools. (Dated 2006-3-27; Editor: Miao Longjun) Author’s profile: Sun Jianguo, male, graduated in 1982 from Tianjin Metallurgical Workers’ University with a degree in metallurgical machinery; currently serves as the deputy chief engineer at Tianjin No. 2 Metallurgical Machinery Factory. With over 20 years of experience in the design, manufacturing, process development, and technical management of metallurgical machinery, I have independently completed the design of various custom-made equipment, including 250 rolling mills, 300 combined reducers, straightening machines, and drawing machines. The design of the 650 mm strip roughing mill was awarded the Group Company’s 2005 Technological Innovation Achievement Award. ———!Research and Applications” —— www.tjyj.com, tjyj@tjyj.com, ww.tjyjqk.com, tjyjzz@tjyj.com. A Brief Overview of Coal Blending for Coking by Jian Shuyan (Tianjin Tietie Coking Chemical Co., Ltd., Tiantie Group, 056404). It discusses the significance of coal blending for coking as well as the coking properties of individual coal types in this technology. A detailed discussion is provided on the quality assessment of coking coal, coal blending methods, and quality control. Keywords: coal blending, coking, cohesion, caking property, additivity, coal blending methods, quality control. 1 Introduction: Tianjin Tiantie Coking Chemical Co., Ltd. owns two of the most advanced JN60-89 coke ovens in China, with an annual production capacity of 1 million tons of coke. The scientific formulation and implementation of coal blending for coking are both key challenges in the company’s production processes as well as drivers for improving the efficiency of its business operations. Faced with the increasingly severe situation of strained coking coal resources and a highly competitive coke sales market, it is all the more important to formulate and implement economically sound coal blending strategies for coking. The Technical Quality Department of my company actively introduces advanced coal and coke analysis equipment. By utilizing techniques such as coal rock analysis, tests using 40 kg coke ovens, analysis of the cold and hot strength of coke, as well as the processing of large amounts of data from routine tests on coal and coke, the department effectively organizes the company’s coal blending and coking processes, providing strong support to frontline production and generating significant economic benefits. 2. The meaning and practical significance of coal blending for coking. Coal blending refers to the process of mixing several different types of coal in certain proportions, based on the requirements for coal quality in coking, so as to enable their properties to complement each other and achieve an overall optimization. Coking refers to the process of high-temperature dry distillation (high-temperature pyrolysis) of coal; that is, a single type of coal with certain caking properties or a mixture of coals is heated to temperatures between 950°C and 1,050°C in an oxygen-free environment, resulting in solid products such as high-temperature coke, gas, and chemical products. The coke produced by our company is manufactured in chamber-type coking ovens, using the coal blending method for coking. Coal is a poor conductor of heat; when charge is loaded into the carbonization chamber, the red-hot furnace walls cause the coal located near them to be heated first. However, it takes a longer time for heat to reach the center of the carbonization chamber; the coal near the furnace walls, once heated, gradually goes through the various stages of thermal decomposition: initial decomposition → formation of gum → semi-coke → coke. As the temperature of the coal in the edge layer increases, heat is gradually transferred toward the center of the carbonization chamber. The gum layer and the semi-coke layer also move continuously toward the center of the carbonization chamber. In the later stages of coking, the gum layers on both sides converge at the center and further solidify into semi-coke. The coking process is completed when the temperature at the center of the carbonization chamber reaches 950°C to 1,000°C. Coke is required to have low ash content, low sulfur content, high strength, and a high degree of anisotropy. To the best of our knowledge, under chamber coking conditions, it is difficult for a single coal type to fully meet the aforementioned requirements when used for coking. Although coking coal can be used alone to produce coke with high strength and good wear resistance, the reserves of coking coal around the world are generally limited and unevenly distributed; relying solely on coking coal for coke production is far from sufficient to meet the needs of industrial development. To conserve high-quality coking coal, it is necessary to combine some of the high-quality coking coals with good caking properties with other coals of moderate or weak caking properties in the coking process, in order to make better use of coals of different grades. Only in this way can…