Coal preparation and processing technology and comprehensive development and utilization of coal
Coal processing and utilization Through a series of processing techniques, the quality of products is improved, and coal varieties that meet the different needs of the use departments are produced, creating conditions for the efficient and clean coal resources. The following is a detailed introduction:
◆ Coal preparation: including screening and coal preparation. The raw coal is first sieved, classified according to the particle size, and the large pieces of vermiculite and debris are excluded. Then, coal is used to screen coal with different properties such as density, sedimentation speed and surface tension of coal, and low-ash clean coal and other products of various specifications are sorted. According to the different sorting medium, the coal is divided into wet coal preparation and dry coal preparation. The former is the main one. The operations included in the operation include crushing, screening, jigging, heavy selection, flotation, special selection, slime water treatment, dewatering, dust removal and drying. These process links work together to form a variety of different processes.
◆ Coal preparation products: According to different uses, there are different requirements for coal preparation products.
(1) The raw coal grades used in clean coal for metallurgical coking are gas coal, fat coal, coking coal, lean coal, 1/3 coking coal, 1/2 medium coal, gas fat coal, lean coal and so on. The main indicators of the product are ash content less than 5.5% to 12.5%, sulfur content less than 0.5% to 2.5%, and moisture less than 12%. Synthetic ammonia coal, using anthracite lump coal as raw material, the main index is less than 10% volatile matter, fixed carbon 56%-75% and more than 75%, sulfur content less than 0.5%-2.0%, ash melting point greater than 1 250～1 350 °C. Generally, the medium-sized fertilizer plant supplies anthracite lump coal of more than 25mm grade, and the small fertilizer plant supplies 13-25mm of smokeless lump coal.
(2) Coal for power generation requires a final coal with a particle size of less than 13 mm. The coal type is not limited, and bituminous coal, anthracite, and lignite may be used. The main indicators are volatiles greater than 6.5, calorific value greater than 11.7 ~ 20.9MJ / kg, sulfur less than 1% ~ 3%, ash melting point greater than 1 350 ° C and so on.
(3) The coal used for steam locomotives is long-burn coal, weak-viscous coal and non-coking coal. The middle block with a particle size of 25 to 50 mm, the mixed medium block of 13 to 50 mm, and the 6 to 50 mm mixed block including the granular coal have a calorific value of more than 21 MJ/kg, and the ash melting point is greater than 1 200 °C.
(4) Civil coal should not burn loose coal and popularize burning coal.
◆ Briquette: The pulverized coal is the main body, with binder and pressure-formed block fuel, which has the dual functions of environmental protection and energy saving. According to the preparation process, it is divided into cold pressing and hot pressing. The former is mainly used, and only the wear resistance of mechanical equipment is required. In terms of binders, organic and inorganic types, organic binders, hydrophobic binders, such as tar pitch, petroleum asphalt, etc., and hydrophilic binders, such as starch, sulfite pulp waste, brewing waste Liquid and the like; inorganic binders include water-soluble water glass and water-insoluble lime, cement and clay. Industrial briquette requires a certain amount of heat, less ash and sulfur, higher ash melting point, less environmental pollution when burning. In addition, the coal is required to be smoothed, crack-free, and has high mechanical strength. The compressive strength of the briquette should be greater than 600-800N. The ratio of the amount of the block that is more than 13mm from the height of 1.85m free fall is called the drop strength of the coal. Up to 95%. At present, China's civil coal accounts for 80% of civilian coal in 1995 and 100% in 2000. Industrial briquette developed late, reaching only about 40% in 2000.
◆Coal slurry: A coal-water mixture prepared by grinding low-ash clean coal (grinding equipment) into fine coal powder, 70% coal, 30% water, and a small amount of chemical additives. Easy to store and transport, can be atomized and burned, high in combustion efficiency, and clean fuel for low pollution. The quality of coal water slurry depends on three factors: coal type, grinding grade combination and additives. The preparation process is to achieve the optimal particle size distribution by grinding the fine-grained coal material, so that the coal can have the highest packing efficiency between the large and small particles. The commonly used methods are wet grinding, high concentration grinding and medium The concentration is ground. The chemical additives used are anionic surfactants, nonionic surfactants, and polymer compounds and inorganic salts. At present, two additive factories in Anhui Huainan and Beijing Yanqing have been built, with an annual production capacity of 3,000 tons. The application benefit of coal water slurry is significant. The first is oil generation benefit. 1.8~2.1t coal water slurry can replace 1t fuel oil. Secondly, it is energy-saving, its combustion efficiency is 5% to 10% higher than that of pulverized coal, and SO2 and NOX emissions are reduced by 20% to 30%, which has environmental benefits. In addition, the coal slurry and flotation tail coal can be used to produce medium-high ash, medium-low concentration coal slurry water coal slurry for heating and burning in the waste rock power boiler, turning waste into treasure.
In the process of coal preparation, a large amount of waste is inevitably generated, and the most common one is coal gangue. In the past, people often abandoned coal gangue, which wastes a lot of resources and seriously pollutes the environment. Under the vigorous appeal and encouragement of national policies, various enterprises and individuals began to develop the available space of coal gangue. Correspondingly, gangue crusher and coal gangue sand making machine came into being. Zhaoyuan Ludong Mining Machinery Co., Ltd. Main mineral processing equipment Flotation machine Gold mining equipment Graphite mining equipment Copper ore equipment Gold-plating equipment Fluorite mining equipment Belt feeding machine company website: http://ludongkj.com/