This paper discusses the factors influencing the selection of surfactant in coal flotation, verifies the promoting effect of surfactant on flotation through experiments, and probes into its optimal dosage. It is found that adding a small amount of surfactant can significantly improve economic benefits. Keywords: surfactant; As a clean coal technology, flotation of clean coal can significantly reduce ash and sulfur. After coal washing, the quality of coal is improved, which can greatly reduce invalid transportation and improve the utilization rate of railways and highways. Among the coal washing processes currently used in China, flotation is still the most effective method to separate fine coal. The problems of low flotation efficiency and high reagent consumption generally exist in China's coal preparation plants. The fine granularity of coal slime is the main reason, and with the development of coal mining mechanization and the change of coal seam, the amount of coal powder in China is relatively increasing, and the floatability is getting worse and worse. Traditional reagents are difficult to float fine particles, and the coal preparation effect is mostly poor, and the variety of composite flotation reagents is far from enough. Surfactant is a chemical reagent, and the interfacial tension of substances can be greatly reduced by adding a small amount. It has the ability to change the properties of gas-liquid interface, liquid-liquid interface and liquid-solid interface, so that it has many properties such as foaming, defoaming, emulsification, dispersion, wetting and solubilization. Therefore, surfactants exist in various fields of human activities and are used in cosmetics preparation, food processing, fiber processing, textile printing and dyeing finishing, pesticide and pharmaceutical processing, mineral flotation, oil exploitation, oil treatment, washing and other industries. Adding surfactants, foaming agents and collectors to coal flotation reagents can improve flotation indexes, fluidity and stability, flotation speed and clean coal yield, reduce reagent consumption and improve clean coal quality, which is non-toxic and harmless and easy to operate. Developing compound flotation reagents is the main trend at present. 1 Influencing factors of surfactant selection1.1influence of HLB value on flotation effect HLB value is hydrophilic and lipophilic balance value. The value used to judge the balance between hydrophilicity and lipophilicity in emulsifier is very valuable in flotation. If the HLB value is 0. 1.2, it plays a defoaming role and does not disperse in water. When the HLB value is 4 ~ 6, its dispersibility in water is very small, so it is used as W/ O emulsifier. 8 ~ 10 emulsion dispersion, stable emulsion dispersion, 12 ~ 14 transparent dispersion; 16 ~ 20 is a soluble agent, a transparent colloidal solution and an O/ W emulsifier. HLB value is closely related to the application performance of surfactants. It has been found that the HLB value of nonionic surfactant in flotation should be between 12 and 16. See table 1 for HLB values of several surfactants in this experiment. Effect of EO addition number 1.2EO addition number, that is, the number of ethylene oxide in nonionic surfactant. At present, it is generally believed that the role of surfactants in coal flotation is mainly hydrogen bond adsorption with coal surface, which is between physical adsorption and chemical adsorption and has a strong effect. Specifically, hydroxyl is the main functional group that forms hydrogen bonds in coal molecules, and it can form different types of hydrogen bonds with different hydrogen bond receptors. When the surfactant contains multiple ether groups, the coal surface and surfactant molecules can form OH? O-type intermolecular hydrogen bond, at this time, the other end of the surfactant is associated with the collector, which makes the polar region of the coal surface become non-polar region, eliminates the influence of oxygen-containing functional groups, and makes the coal more hydrophobic, thus improving the flotation effect. The influence of 1.3 concentration A large number of flotation experiments have found that with the increase of surfactant dosage, its promoting effect on coal flotation is not simply proportional to the dosage. The later experiments will be discussed in detail, and will not be mentioned for the time being. 2 test part 2. 1 materials and instruments 1 test materials are taken from collectors, foaming agents and slime samples provided by the laboratory.