Method for preparing calcium fluoride from phosphorous ore-associated fluorine resources

Abstract

The invention discloses a method for preparing calcium fluoride from phosphorous ore-associated fluorine resources, and belongs to the technical field of phosphorus chemical engineering. The method comprises the steps: performing a reaction on a fluorine-containing compound and potassium hydroxide, performing solid-liquid separation after completion of the reaction so as to obtain a silicon-containing potassium fluoride solution, adding a fluorosilicic acid to the silicon-containing potassium fluoride solution so as to adjust the pH value, performing filter separation so as to obtain a potassium fluoride solution and silica-potassium fluorosilicate solid, returning the silica-potassium fluorosilicate solid to the first step, performing a reaction on the potassium fluoride solution an calcium hydroxide, performing solid-liquid separation after completion of the reaction so as to obtain calcium fluoride and a potassium hydroxide filtrate, recycling a part of the potassium hydroxide filtrate to the first step, and concentrating the remaining potassium hydroxide solution so as to obtain a potassium hydroxide product. The shortcoming that fluorine-containing compounds in by-products ofa wet preparation process of phosphoric acid cannot be utilized other than fluorosilicic acid in the prior art is overcome, full utilization of the fluorine-containing compounds is achieved, and meanwhile the waste fluorine-containing compounds can be processed into high-value calcium fluoride, potassium hydroxide and silicon dioxide.

Description

technical field [0001] The invention belongs to the technical field of phosphorus chemical industry, and in particular relates to a method for preparing calcium fluoride from phosphate rock associated fluorine resources. Background technique [0002] During the production process of wet-process phosphoric acid, a large amount of fluorine-containing compounds will be produced by-product, including fluosilicic acid obtained by absorbing tail gas, deposits in phosphoric acid storage tanks (hereinafter referred to as deposits), and scales in phosphoric acid delivery pipelines (hereinafter referred to as Scales), crystals in the return pipe of the phosphogypsum reservoir (hereinafter referred to as crystals), precipitates produced during the defluorination of dilute phosphoric acid (hereinafter referred to as defluorinated products), etc. In addition to industrial applications, such as processing into hydrogen fluoride, sodium fluorosilicate, ammonium fluoride and other products,...

AI Technical Summary

Problems solved by technology

These two patents can obtain calcium fluoride products, but they cannot be applied to deposits, scales, crystals and defluorinated substances, so the scope of application is limited, only limited to relatively pure fluosilicic acid

In addition, both patents require the use of difficult-to-recycle ammonia as the circulating medium, which poses greater safety and environmental risks, and requires higher safety and environmental protection devices; the by-product ammonia water needs to be heated and evaporated to achieve recycling and water balance , will inevitably increase energy consumption; expensive ammonia consumption will become another weakness of this type of method

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