Crystallization system apparatus for generating sodium fluoroaluminate crystals from hydrofluoric acid solution, and crystallization operating control method thereof

Abstract

The invention provides a crystallization system apparatus for generating sodium fluoroaluminate crystals from a hydrofluoric acid solution, and a crystallization operating control method thereof. The apparatus mainly comprises a crystallization reaction tank, a sodium aluminate drug tank, a high concentration hydrofluoric acid waste liquid tank, a pH value / fluorinion detection section, a dehydrator and a low concentration hydrofluoric acid waste liquid tank. The control method comprises the following steps: the liquid flow form and the flow amount of a contact reaction of a sodium aluminate drug and a hydrofluoric acid waste liquid are controlled through a dispersion plate and a control plate in the crystallization reaction tank, and factors influencing the crystallization purity in the control system operating process are determined by means of the pH value / fluorinion detection section connected with the crystallization reaction tank in a loop form and cooperating with monitoring of the pH value and the fluorinion concentration in a hydrofluoric acid waste liquid and sodium aluminate drug mixed water sample in order to make the system stably produce cryolite with high crystallization purity and high economic benefit.

Description

technical field [0001] The present invention relates to a crystallization system equipment, in particular to a method for generating sodium fluoroaluminate from hydrofluoric acid waste liquid by using flow control and pH value and fluoride ion concentration monitoring to achieve the formation of sodium fluoroaluminate crystals with high economic benefits Crystallization system equipment and crystallization operation control method thereof. Background technique [0002] Press, high-concentration hydrofluoric acid (HF, 49%) or hydrofluoric acid mixed acid is widely used in etching technology for semiconductor (IC), liquid crystal display panel (TFT-LCD), solar cells and other technology industries, so the output The bulky hydrofluoric acid waste acid with concentration as high as 49% or as low as 0.5% requires waste liquid treatment. [0003] At present, the hydrofluoric acid waste liquid treatment method is to add calcium-containing compounds such as CaO, Ca(OH)2, CaCl2, etc...

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Problems solved by technology

[0005] Although the technical solution proposed by the inventor of this case has been able to obtain cryolite crystals with a purity as high as 96%, the factors affecting the crystal purity include not only the liquid flow contact reaction method between hydrofluoric acid and sodium aluminate, but also impurities in the solvent. content, solution pH value and other influencing factors, so the inventor of this case believes that there is still room for further improvement in the aforementioned technical solutions

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