Method for preparing calcium fluoride from fluorine-containing wastewater

Abstract

The invention relates to a method for preparing calcium fluoride from fluorine-containing wastewater. The preparation method comprises the following steps: carrying out decomposition reaction on a calcium-containing raw material and a dissolution medium, carrying out carbonization conversion reaction on a calcium-containing solution obtained by the decomposition reaction and carbon dioxide, and mixing and reacting a calcium carbonate solid obtained by the carbonization conversion reaction with the fluorine-containing wastewater and an additive to obtain a calcium fluoride solid. According to the preparation method, a high-quality artificial fluorite product with controllable morphology, controllable granularity and controllable purity can be prepared, and the fluorine resource recovery rate can be increased to 90% or above; and in addition, the preparation method realizes efficient circulation of the medium and carbon dioxide, avoids the generation of fluorine-containing sludge, and has the advantages of mild process conditions, no special requirements on equipment materials and types, strong industrial operability and wide application range.

Description

technical field [0001] The invention relates to the field of fluorine-containing wastewater treatment, in particular to a method for preparing calcium fluoride from fluorine-containing wastewater. Background technique [0002] Fluorspar, also known as fluorspar, is mainly composed of calcium fluoride (CaF 2 ), is my country's strategic mineral resources, has the scarcity and strategic significance of "rare earth", and its application fields cover chemical industry, metallurgy, cement, glass, ceramics, optics, electronics, new energy, national defense, medicine and other traditional and emerging industries . Because of its irreplaceable use, it is known as the "second rare earth". [0003] According to the "Mineral Commodity Summaries 2019" released by the US Geological Survey, the world's fluorite resource reserves are 310 million tons, and my country's fluorite resource reserves are 42 million tons, accounting for 13.5% of the world. However, my country's annual fluorspar...

AI Technical Summary

Problems solved by technology

Although the method improves the purity of calcium fluoride in the fluorine-containing sludge and solves the problem that small particles of calcium fluoride are difficult to settle and separate, the resulting fluorine-containing sludge still needs to be further separated into high-quality calcium fluoride solids. There is still the problem of secondary pollution, and the process of the method is cumbersome, the operation is complicated, the residence time is long, and the investment in equipment is high

[0012] In summary, although the prior art discloses some treatment methods for fluorine-containing wastewater, and some treatment methods can even separate high-purity calcium fluoride solids from fluoride-containing wastewater, there are still cumbersome technological processes and high equipment investment. , long residence time, secondary pollution of fluorine-containing sludge, etc., and the separated calcium fluoride solid cannot achieve controllable shape, controllable particle size, and controllable purity

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