1 classification of coal With the development of society and the advancement of science, the use of coal has become more and more extensive. People have become more and more aware of the nature, composition and application of coal, and gradually found that all kinds of coal have the same place and different characteristics. Different types of coal are summarized and divided into several categories of similar nature according to various needs. In this way, the concept of coal classification is formed. For different priorities, coal classification methods are: (1) Classification of coal genesis: classification of raw materials and accumulation environment of coal, called the genetic classification of coal; (2) Scientific classification of coal: classification of basic properties such as elemental composition of coal, called scientific classification; (3) Practical classification of coal: The practical classification of coal is also called the industrial classification of coal. Classified according to the process properties and uses of coal, called the practical classification. The coal classification in China and the coal classification in all major industrial countries are all practical classifications. The following is a detailed description of the practical classification of coal in China. According to the coalification degree of coal, all coals in China are divided into three major coal types: lignite, bituminous coal and anthracite. According to the degree of coalification and the characteristics of industrial utilization, the lignite is divided into two sub-categories, and the anthracite is divided into three sub-categories. Bituminous coal is more complicated, divided into 4 grades according to volatile matter, namely Vdaf>10%～20%, Vdaf>20%～28%, Vdaf>28%～37% and Vdaf>37%, which are divided into low, medium and medium high. And high four volatile bituminous coal. According to the adhesion, it can be divided into 5 or 6 grades, that is, the bond index GR.I. is 0-5, which is called unbonded or weakly bonded coal; GR.I.>5-20, called weak bond Coal; GR.I.>20～50, called medium-weak cohesive coal; GR.I.>50-65, called medium-strong cohesive coal; GR.I.>65, called strong cohesive coal. In strongly cohesive coal, if y>25mm or b>150% (for Vdaf>28%, fat coal, b>220%), it is called extra strong cohesive coal. See GB5751-1986. The basic characteristics of various types of coal are as follows: (1) Anthracite (WY). Anthracite has a high fixed carbon content, low volatile yield, high density, high hardness, high ignition point, and no smoke when burning. No. 01 anthracite is aged anthracite; No. 02 anthracite is typical anthracite; No. 03 anthracite is young anthracite. For example, Beijing, Jincheng and Yangquan are anthracite 01, 02 and 03 respectively. (2) Lean coal (PM). Lean coal is the kind of bituminous coal with the highest degree of coalification, and it is not bonded or slightly cohesive. No coking in the layered coke oven. The flame is short when burning and is resistant to burning. (3) Lean coal (PS). Lean coal is a kind of bituminous coal with high metamorphism, low volatile content and weak cohesiveness. Coking is worse than typical lean coal. When coking alone, more coke powder is produced. (4) Thin coal (SM). Thin coal is a medium-cohesive coking coal with low volatility. A certain amount of colloidal bodies can be produced during coking. When coke alone, can be obtained of the block, less cracking, crushing is better coke, coke but poor abrasion resistance. (5) Coking coal (JM). Coking coal is a medium- and low-volatility medium-bonding and strong-adhesive bituminous coal. When heated, it produces a colloid with high thermal stability. When coking alone, coke with large blockiness, less cracks and high crushing strength can be obtained, and the wear resistance is also good. However, when coking alone, the expansion pressure generated is large, making it difficult to push the coke. (6) Fat coal (FM). Fat coal is a strong, cohesive bituminous coal with low, medium and high volatiles. It produces a large amount of colloidal bodies when heated. When coking alone, it can produce coke with good meltability and high strength, and its wear resistance is better than coking coal coke. The disadvantage is that the coke is separately produced, the transverse crack is more, and the char root part often has bee coke. (7) 1/3 coking coal (1/3 JM). 1/3 coking coal is a new type of coal. It is a kind of bituminous coal with medium and high volatile content and strong cohesiveness. It is also a transitional coal between coking coal, fat coal and gas coal. Separate coking can produce coke with better meltability and higher strength. (8) Gas and fat coal (QF). Gas-fertilizer coal is a kind of strong-bonded fat coal with high volatile matter and colloidal layer, and some are called liquid fat coal. Coking performance is between fat coal and gas coal, which produces a large amount of gas and liquid chemicals when coking alone. (9) Gas coal (QM). Gas coal is a coking coal with a shallow degree of coalification. It produces higher volatiles and more tar when heated. The colloidal body has lower thermal stability than the fat coal and can be coked separately. However, coke is mostly slender and brittle, and there are many longitudinal cracks. Therefore, the crushing strength and wear resistance of coke are worse than other coking coals. (10) 1/2 medium coal (1/2ZN). 1/2 medium coal is a medium-adhesive medium and high volatile bituminous coal. Some of them can form a certain strength of coke when coking alone, and can be used as a raw material for coking coal blending. When a part of coal with poor cohesiveness is separately coked, the coke formed is inferior in strength and the coke rate is high. (11) Wet sticky coal (RN). Weak coal is a kind of bituminous coal with weak cohesiveness from low metamorphism to moderate metamorphism. When heated, less colloid is produced. When coking alone, some can form small cokes with poor strength, while others only have a small amount of coagulation, and the coke rate is high. (12) Non-stick coal (BN). Non-stick coal is a bituminous coal with a low metamorphic level to a moderate metamorphism level that has been subjected to considerable oxidation at the beginning of coal formation. When heated, substantially no colloid is produced. Coal has a large amount of water, and some also contain certain secondary humic acid, which contains more oxygen, and some of them are as high as 10% or more. (13) Long flame coal (CY). Long-flame coal is the lowest level of bituminous coal, from non-adhesive to weakly cohesive. The youngest of them also contains a certain amount of humic acid. It is easy to weather and crack when stored. Old coal with a high degree of coalification can produce a certain amount of colloidal body when heated. Small coke can also be formed when coking alone, but the strength is extremely poor and the coke rate is high. (14) Brown coal (HM). Lignite is divided into two types: young lignite with a transmittance of Pm < 30% and old brown coal with a Pm > 30 to 50%. Lignite is characterized by large water content, low density, no cohesiveness, and contains different amounts of humic acid, which has high oxygen content. It is often around 15 to 30%. It has strong chemical reactivity and poor thermal stability. The lump coal is severely broken when heated. It is easy to weather and deteriorate in the storage air, and it is broken and even powdery. The calorific value is low, the coal ash has a low melting point, and the ash contains more CaO and less Al2O3. 2 Raw coal and fine coal washing performance indicators 3 Clean coal technology Clean coal technology is a general term for new technologies such as processing, combustion, conversion and pollution control aimed at reducing pollution emissions and improving utilization efficiency from the development to the utilization of coal. 3.1 Overview of foreign development of clean coal technology In March 1986, the United States took the lead in launching the Clean Coal Technology Demonstration Project (CCTP), which consists of four main areas: (1) advanced coal-fired power generation technology (integrated coal gasification combined cycle power generation - IGCC, fluidized bed combustion - CFBC, improved combustion and direct coal-fired heat engine); (2) Environmental equipment (NOX and SOX control); (3) the coal is processed into clean energy technology (washing, mild gasification, liquefaction); (4) industrial Applicability (ironmaking , cement and other industries control sulfur, nitrogen, dust emissions and flue gas recovery and washing, etc.). 13 preliminary commercialization results have been achieved. Projects under development in the European Community are coal gasification combined cycle power generation (IGCC), coal and biomass and waste combined gasification (or combustion), circulating fluidized bed combustion, solid fuel gasification and fuel cell combined cycle technology. Wait. In recent years, Japan has begun to increase the consumption of coal by a large margin, and the development of clean coal technology has become a hot spot. Projects under development include (1) technologies to improve coal utilization efficiency, such as IGCC, CFBC and PFBC; (2) desulfurization and denitrification technologies, such as advanced coal washing technology, oxy-combustion technology, advanced waste smoke treatment technology, Advanced coke production technology; (3) Coal conversion technology, such as coal direct liquefaction, hydrogenation, coal gasification combined fuel cell and coal pyrolysis; (4) effective utilization of fly ash. 3.2 Overview of domestic development of clean coal technology China has carried out a large number of research and development and promotion work to improve the efficiency of coal development and utilization and reduce environmental pollution. With the transformation of the country's macro-development strategy, clean coal technology has received strong support from the government as one of the strategic measures for sustainable development and the realization of two fundamental changes. In 1995, the State Council established the "National Clean Coal Technology Promotion Planning Leading Group", organized and formulated the "China Clean Coal Technology" Ninth Five-Year Plan and the 2010 Development Outline, and was approved by the State Council in June 1997. The China Clean Coal Technology Program framework covers four areas (coal processing, efficient coal combustion, coal conversion, pollution emission control and waste disposal), including 14 technologies, namely: coal washing, briquette, coal water slurry; Circulating fluidized bed power generation technology, pressurized fluidized bed power generation technology, integrated gasification combined cycle power generation technology; coal gasification, coal liquefaction, fuel cells; flue gas purification, comprehensive utilization of power plant fly ash, development and utilization of coalbed methane, Comprehensive utilization of coal gangue and slime water, industrial boilers and kilns. 4 heavy medium coal preparation Heavy medium coal preparation is a gravity coal preparation method that uses a heavy liquid or a heavy suspension having a density greater than water and between coal and vermiculite as a medium for sorting. Depending on the medium used, it can be divided into two categories: heavy liquid coal preparation and heavy suspension coal preparation. Heavy liquid refers to an aqueous solution of certain inorganic salts and a high density organic solution. The resuspension is a two-phase fluid having a certain density and suspension by weighting (high-density solid particles) and water. When the raw coal is fed into the suspension sorting machine, the coal having a density smaller than the suspension floats, and the vermiculite (or medium coal) which is larger than the density of the suspension sinks, and is sorted according to the labor density. Heavy liquid coal is highly corrosive due to medium, difficult to recover, high in cost, and not applicable in industry. At present, the widely used in production is the re-suspension coal preparation, and the weighing medium is used for coal preparation. According to different sorting conditions, heavy medium selection can be divided into two categories in the gravity field sorting and in the centrifugal force field. The former is mainly used to select lump coal (greater than 13mm), and it is sorted and sorted in the heavy mass sorting machine. The latter is mostly used for sorting and sorting with heavy medium cyclone. Heavy medium coal preparation is the most efficient coal preparation method at present, and its special occupation is: 1 high precision of sorting; 2 wide range of density adjustment; easy to achieve automatic control; 3 adaptation of quantity and quality fluctuation of selected raw coal Strong; 4 sorting particle size range is wide, the particle size of the lump coal separator is generally 300~13mm, the swirler feed size is usually 13~0.15mm; 5 important quality must be added in the production process, there must be in the process flow Medium preparation and purification and recovery system; 6 equipment wear is serious, and the chute and pipeline should be made of wear-resistant materials to reduce maintenance. Hulled Hemp Seed, which is the whole seed with the crunchy outer shell removed, comes by quite a few names like Hemp Hearts, shelled Hemp Seed and hemp nut. 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