A leaching agent based on high-concentration brine in coal chemical industry

Abstract

The invention discloses a leaching agent based on high-concentration saline water in the coal chemical industry. The leaching agent comprises the high-concentration saline water, fresh water or brackish water and old brine which are mixed in a mass ratio of a:(1-a):(2-6), wherein a is larger than zero and smaller or equal to 0.1; the leaching agent comprises, by mass, 20-26% of MgCl2, 0.8-1.4% of NaCl and no more than 0.8% of KCl. Combined with a salt lake solution mining technology and a potassium fertilizer production technology, the waste water, namely the high-concentration saline water, generated in the coal chemical industry is directly used for preparing the leaching agent for salt lake resource development, so that salt lake solid carnallite potassium deposit is mined in a leaching mode, carnallite saturated bittern is obtained, and then industrial grade KCl products are produced. By means of the leaching agent, the solid waste landfill investment cost in existing high-concentration saline water treatment is reduced, the freshwater consumption in an original salt lake solution mining technology is also reduced, and a feasible recycling process route is provided for the comprehensive utilization of the high-concentration saline water in the coal chemical industry and the coal chemical industry development.

Description

Technical field [0001] The invention belongs to the technical field of coal chemical industry. Specifically, it relates to a leaching agent based on high-concentration brine in coal chemical industry. Background technique [0002] Modern coal chemical industry refers to the process of using coal as raw material and adopting new and advanced chemical processing technology to transform coal into gas, liquid, solid fuel or intermediate products, mainly including coal gasification, liquefaction, and low-temperature pyrolysis as the leading production synthesis Energy and chemical industries such as natural gas, synthetic oil, and chemical products. As the world's oil and gas resources become increasingly tight, combined with my country's resource endowment characteristics of "oil shortage, gas shortage, and relatively abundant coal resources", coal chemical industry has broad development prospects in China. [0003] A major feature of the coal chemical industry is its large water cons...

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Problems solved by technology

However, the above-mentioned existing treatment methods have the following disadvantages: (1) The evaporation pond technology is suitable for the northwest region with vast territory, dry climate, small precipitation, large evaporation, and abundant solar energy. During the evaporation process, some pollutants will enter the atmosphere , causing pollution; the operation mode of the evaporation pond is not appropriate, the high-concentration brine cannot be evaporated, the area and volume of the evaporation pond are small, the evaporation pond is continuously expanded, and the evaporation pond eventually becomes a sewage reservoir. The construction mode of the evaporation pond currently in operation is generally not It is constructed according to the model of sewage reservoir, without grading. Too little grading is not conducive to making full use of the advantages of fast evaporation speed of low-concentration brine, thus reducing the overall evaporation rate of the evaporation pond; too much grading will not only increase the amount of dam construction, but also cannot Significantly increase the evaporation rate; at the same time, there are multiple environmental hazards in the operation of the evaporation pond, including heavy metals and organic pollutants contained in the high-concentration brine received by the evaporation pond, which has potential pollution to groundwater

In addition, it is necessary to build a large-volume temporary wastewater storage tank, and the capacity of the wastewater temporary storage tank generally requires hundreds of thousands or even nearly one million cubic meters, with an investment of hundreds of millions of yuan

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