Coal is a complex mixture of types of coal sulfide complex. According to the existence of different forms of coal, coal sulfur can be divided into two categories of organic sulfur and inorganic sulfur. Inorganic sulfur is the mineral in coal, and there are three main existing forms: pyrite sulfur (FeS2), sulphate sulfur (mainly CaSO4 and FeSO4) and elemental sulfur (S6, S7, S8, etc.) Content and its degree of deterioration of little relationship. Sulfur and organic molecules cross-linked to form organic sulfur present in the coal. Organic sulfur in coal accounts for about 1/2 or more of the total sulfur in the coal. According to the different structures, it can be divided into aliphatic sulfides, aromatic sulfides and heterocyclic sulfides. At present, the common coal pre-combustion desulfurization technology is based on the corresponding stage of coal development and utilization, using physical desulfurization, chemical desulfurization and biological desulfurization process, the implementation of coal combustion before the desulfurization, combustion of sulfur, post-combustion desulfurization. Pre-combustion sorting desulfurization more economical, but less efficient removal of inorganic sulfur in coal; sulfur in the combustion of sulfur is mainly added to the sulfur in the coal will be fixed in the cinder, less investment, low operating costs, does not produce However, the desulfurization efficiency is very low. The post-combustion desulfurization is mainly the flue gas desulfurization technology, which has high desulfurization efficiency. However, the process is complex, the investment and operation costs are high, and the occupation area is relatively large. Physical desulfurization is based on coal and sulfur compounds in the surface chemical properties, electrical, magnetic and density differences and other methods to remove inorganic sulfur in coal. Commonly used methods are re-election, flotation, electricity election, selective flocculation, magnetic separation dry election method, microwave treatment and radiation desulfurization method. Physical desulfurization has the advantages of simple process, relatively low cost, easy mass production and the like. However, it can only remove inorganic sulfur from coal and hardly remove organic sulfur and is not suitable for desulfurization before combustion. Chemical desulfurization is mainly the use of oxidant sulfur oxidation or displacement out of the purpose of desulfurization, is a coal-free ultra-low sulfur coal preparation methods. Chemical desulfurization efficiency is higher, can remove most of the inorganic sulfur and a considerable part of the organic sulfur. The method can be divided into hot pressing leaching method, atmospheric pressure wet method, solvent method, high temperature pyrolysis gas method and chemical crushing method. Some of the research results also use microwave radiation to strengthen the chemical desulfurization process. Hot pressing leaching method has the following three kinds: hot lye leaching method, Meyers method and oxidation desulfurization. Hot lye leaching method, also known as hydrothermal method, is the use of Na2CO3 34% ~ 10% and Ca (OH) 22% of the mixed aqueous solution as a leaching agent, coal pyrite can be converted into soluble sulfide, thiosulfate, Organic sulfur into hydrogen sulfide, so as to achieve the purpose of desulfurization. Meyers law is the use of ferric oxide Fe2 (SO4) 3 oxidation of pyrite into soluble FeSO4, organic sulfur does not work. Oxidation desulfurization is the use of air at higher temperatures and pressures oxidized pyrite and organic sulfur in the coal to produce soluble sulfate or sulfuric acid. Atmospheric pressure wet method mainly has the following two kinds: KVB method and chlorination method. KVB method is the use of NO2 under normal pressure selective oxidation of sulfur in coal components, and washed with water or hot lye and then washed to remove sulfur in coal. Chlorination also known as JPL method, under the action of chlorination, pyrite can be oxidized to ferric chloride and sulfuric acid, organic sulfur can be oxidized to sulfonic acid or sulfuric acid. There are three main solvent methods: melting alkali, organic solvent extraction and supercritical fluid extraction. Melting alkali method is used to carry out desulfurization of molten alkali, molten alkali with the coal in the minerals, organic sulfur react to form soluble substances, resulting in purified coal, and even can be ultra-clean coal. Organic solvent extraction is currently relatively mature perchlorethylene desulfurization process, which is the use of perchlorethylene extraction of organic sulfur in coal, and pyrite and other minerals are removed by gravity floating, the extract of other hydrocarbons The compound content is less than 0.5% of the organic matter of raw coal. The application of supercritical fluid extraction in desulfurization is a new method that has emerged in recent years. Methanol and ethanol are added into the coal, and the hydrogen bonding and dipole attraction in the alcohol are used to increase the dissolving ability of organic substances in the coal so as to achieve the purpose of desulfurization. The method is mainly used to remove organic sulfur, desulfurization rate of up to 57.8%. High-temperature pyrolysis gas method is the use of hydrogenation reaction, under high temperature and high pressure coal sulfur will be converted to hydrogen sulfide to produce clean semi-coke for the purpose. The method can greatly improve the tar, crude benzene recovery, easy chemical use. Chemical crushing is the use of a low molecular weight compound (usually liquid ammonia or concentrated ammonia) to rapidly penetrate into natural fractures in coal and destroy the bonds in the coal so that the coal surface along the bedding and mineral and coal Selective fragmentation of organic matter on the binding surface. Coal biological desulfurization technology mainly refers to the microbial desulfurization, that is, under the normal temperature and pressure using the microbial metabolic processes of the redox reaction to selectively remove organic sulfur and inorganic sulfur in coal to achieve the purpose of desulfurization. The utility model has the advantages of not only removing inorganic sulfur with complicated structure and fine grain size, but also removing part of organic sulfur, less investment, low operation cost and good desulfurization effect. Insufficient space is occupied, a long time, and microbial bacteria on the oxygen content of the environment, temperature, humidity, pressure adaptability restrictions. Currently, the more mature biological desulfurization technology mainly leaching desulfurization, surface modification, biological flotation, biological selective flocculation, but no one method in the industrial use of large area. Desulfurization compared to other processes such as sulfur fixation in the reaction and after-combustion post-combustion desulfurization, pre-combustion desulfurization or pre-reaction desulfurization have great advantages, but the current technology only physical desulfurization technology can be widely used, but also Has considerable coal selectivity. The way that chemical desulfurization is over-cost is the crux of its inability to be widely used. Biological desulfurization reaction time can take up to one year, which is the key factor restricting its development. If we can combine the advantages of each way and method of combination treatment, then the advantages of each one come into play.