Method for producing industrial calcium fluosilicate

Abstract

The invention discloses a method for producing industrial calcium fluosilicate, wherein calcium carbonate and fluosilicic acid of a phosphatic fertilizer byproduct or fluosilicic acid generated as a byproduct in a wet-process phosphoric acid production process are used as raw materials. The method comprises the steps of: firstly, introducing fluosilicic acid out of a system, and adding the calcium carbonate to prepare a fluosilicic acid saturated solution, wherein the molecular proportion of the added calcium carbonate to the fluosilicic acid is 0.95-100; introducing a saturated solution or an upper-layer calcium fluosilicate solution generated through settlement separation, and a centrifugally separated mother solution and a centrifugally separated crystallizing washing solution into a phosphatic fertilizer or wet-process phosphoric acid production system to replace the conventional supplementary water to be used as a washing and absorbing solution for fluorine-containing tail gas; then, taking out a circulatory washing solution, adding the calcium carbonate to prepare a solution with the proportion of Ca<2+> to SiF6<2-> of (0.9-1.05):1, and carrying out centrifugal separation orspraying drying on lower-layer calcium fluosilicate thick liquid generated through separation of cooled crystallized slurry to obtain a calcium fluosilicate product of an industrial grade. The methodhas the obvious advantages of no emission of three wastes, good environmental adaptability, low production cost, high product purity and good quality.

Description

A kind of production method of industrial calcium fluorosilicate technical field The invention relates to a production method of calcium fluorosilicate, in particular to a method for absorbing silicon tetrafluoride and hydrogen fluoride by-products in the production of phosphate fertilizer or wet-process phosphoric acid with calcium fluorosilicate solution, and then using calcium carbonate to neutralize the fluorine-containing silicon The invention discloses a fluorosilicate solution of calcium hydrogenate and a method for producing calcium fluorosilicate, belonging to the technical field of chemical production. Background technique Industrial calcium fluorosilicate is white crystalline powder. Partially decomposes in hot water. Soluble in fluosilicic acid and hydrofluoric acid, insoluble in ethanol, almost insoluble in cold water and acetone. Mainly used in wood, rubber and fabric industries. Also used as a floating detergent and insecticide. The traditional producti...

AI Technical Summary

Problems solved by technology

The traditional production method of calcium fluorosilicate is to use calcium oxide and industrial fluorosilicic acid as raw materials. Due to the strong alkali of calcium oxide, the calcium fluorosilicate formed in the production process is easily decomposed into calcium fluoride, thereby reducing the amount of fluorosilicic acid. The yield of calcium, the product purity is low, the use is greatly limited, and the consumption of raw materials is high

Calcium carbonate is used as raw material to directly react with fluosilicic acid. Due to the large amount of foam generated in the production process, the production is difficult to control and has not been used.

At the same time, due to the low concentration and high impurity content of fluosilicic acid, a by-product of phosphate fertilizer or wet-process phosphoric acid production, conventional methods are used to produce low-value sodium fluorosilicate, resulting in the recovery of by-product fluorine silicon It is difficult for acid resources to give full play to their economic advantages for a long time. Moreover, sodium fluorosilicate is produced with low-concentration by-product fluorosilicate. During the production process, a large amount of dilute acid and a large amount of sodium ions are produced, which cannot be returned to the system for digestion. The environmental pollution pressure is huge. A small number of production plants have been shut down, and the by-product fluosilicic acid in the phosphate fertilizer industry and wet-process phosphoric acid production is looking for a new outlet