Method for preparing calcium sulfate from fluorite mine calcium-containing waste liquid

Abstract

The invention provides a method for preparing a calcium sulfate product by using fluorite mine calcium-containing waste liquid. The method comprises the following steps: S1, sequentially adding the fluorite mine calcium-containing waste liquid and a solution containing SO4<2-> ions into a reaction container, and carrying out a crystallization precipitation reaction; S2, controlling the crystallization rate of calcium sulfate generated in the crystallization precipitation reaction to obtain calcium sulfate crystal slurry; and S3, subjecting the calcium sulfate crystal slurry obtained in the step S2 to filtering, and conducting leaching and drying to obtain a solid-phase product which is a calcium sulfate needle-shaped or whisker-shaped sponge body and a filtrate which is diluted hydrochloric acid. The average particle size of calcium sulfate is larger than or equal to 150 micrometers, the dry basis purity is larger than or equal to 95%, the whiteness is larger than or equal to 90, the calcium sulfate crystal is a high-quality crystallized calcium sulfate product, the whole process is simple and easy to implement, and the method is a method for effectively utilizing resources and reducing pollution.

Description

technical field [0001] The invention relates to a harmless treatment method for calcium-containing waste liquid, in particular to a method for preparing a high-quality calcium sulfate product from the calcium-containing waste liquid produced by acid leaching and purification of fluorite concentrate. Background technique [0002] Fluorspar, also known as fluorspar, is the main source of fluorine in industry and one of the more than 20 important non-metallic mineral raw materials in the world. Fluorite has a wide range of uses, and with the advancement of science and technology, its application prospects are becoming wider and wider. At present, it is mainly used in metallurgy, aluminum smelting, glass, ceramics, cement, and chemical industries. Pure, colorless and transparent fluorite can be used as an optical material, and brightly colored fluorite can also be used as a raw material for gemstones, jade, and arts and crafts carvings. Fluorite is also the basic raw material ...

AI Technical Summary

Problems solved by technology

Although the harmless treatment of the calcium-containing waste liquid has a novel process, the average particle size of the finally obtained calcium sulfate dihydrate is 0.1-0.3mm, and the calcium sulfate content after drying can reach more than 98%, which is in line with GB1852-2007 food additive calcium sulfate requirements, but it needs to refine sulfate-containing brine and calcium-containing brine in advance, and needs to use special control crystallization reactors and circulation lifting devices and other reaction equipment. The maintenance costs are high, and the process conditions are harsh. SO 4 2- and Ca 2+ The molar ratio is strictly controlled at 1:1, which is difficult to control so accurately in actual production. SO in brine containing sulfate 4 2- The mass concentration is low. In actual production, crystallization reactors and supporting settlers, transfer pumps, and pipelines are relatively large, and the investment is relatively high.

In addition, the invention does not apply mathematical algorithms to realize automatic control, which is not conducive to the process control of large-scale production, so the invention cannot be simply used for environmental protection wastewater treatment projects with strict investment and operating costs

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