CN1131124A

CN1131124A - Producing sodium fluorosilicate by using fluorite as raw material

Info

Publication number: CN1131124A
Application number: CN 95100688
Authority: CN
Inventors: 余世柏
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-03-16
Filing date: 1995-03-16
Publication date: 1996-09-18

Abstract

The present invention relates to a method for producing sodium fluorosilicate by using fluorite. Said invention is different from original production process in that it has no need of HF and SiF4 gas state process, and can directly obtain soluble fluorosilicate solution in the presence of catalyst, and then can convert it into sodium fluorosilicate. Its production process is simple, free from consumption of energy source, and its by-product gypsum is directly salable, and the sulfuric acid produced finally in the solution also can be directly repeatedly used.

Description

Production of sodium fluosilicate from fluorite

Sodium fluosilicate is a chemical product with wide application, and the industrial waste gas SIF of calcium superphosphate produced by phosphate fertilizer plants is almost used in the past₄The yield is restricted by the production of phosphate fertilizer, and the demand of the market can not be met.

China has abundant fluorite reserves, and although mining exists in various places, the mining amount is not large because of few purposes (mainly used as a fluxing agent in metal smelting).

The invention aims to develop and use fluorite, and produce sodium fluosilicate by using the fluorite as a main raw material, and open up a new way for producing sodium fluosilicate.

The main chemical component of fluorite is CaF₂The chemical property of the substance is very stable, and the substance can be decomposed by concentrated sulfuric acid at normal temperature and normal pressure, is almost insoluble in various solvents, and does not have chemical reaction with other substances. The invention uses NH⁺ ₄As a catalyst, can make CaF₂And SiO₂Reacting with dilute sulfuric acid to generate H₂SiF₄Dissolving to obtain Na₂SiF₄(sodium fluorosilicate).

The chemical reaction formula is as follows:

the biggest difference between the production process of the invention and the prior production process is that HF and SiF are not passed through₄In the gaseous state of NH⁺ ₄In the presence of (A), F is converted into stable [ SiF]₄]"Complex ions exist in the reverse directionIn solution so that the content of F ions in the solution is lower than that of CaF₂The ion product concentration of (a) to complete the chemical reaction. The solution after reaction contains other soluble sulfate, phosphate, borate and the like. But the sodium salts of the acid radicals are soluble in water, the sodium fluosilicate is easy to separate from the acid radicals, and the purification procedure is simple.

The invention has simple process, changeable production scale, no energy consumption, no HF and SiF₄And the like. The byproduct is gypsum which can be directly sold as commodity or processed into other finished products, and H is finally generated by reaction₂SO₄Can be repeatedly and directly used in the production process to save the using amount of the sulfuric acid. Basically has no three-waste discharge, less investment, quick effect and better economic benefit.

The specific operation process is as follows:

at 10M⁺About 3.0 tons of water was added to the reaction tank (9) and (NH) was added thereto₄)₂SO₄0.7 ton, 1.56 ton of 49N industrial sulfuric acid, adding water to 6.0 ton, stirring, adding 1.25 ton of fluorite mineral powder and proper quantity of quartz powder (CaF in fluorite)₂Adding quartz when the content is below 80%, adding quartz powder with fluorite content of 5-20% when the content is above 80%), stirring, reacting for 6-8 hr until the precipitate turns white and easily adheres to the wall of the vessel, filtering to obtain filtrate, washing the filtrate with 100Kg of water twice, mixing the washing solution with the filtrate, and collecting 10m (containing Na) in 6 ton₂SiF₄1.0 g) of the solution was added with 3.0ml of saturated NaCl solution, placed in a refrigerator for half an hour, titrated with 1.0N standard NaOH solution at 0 ℃ with bromothymol blue as indicator to a stable blue colour, the free acid content was calculated and about 20ml of 1.0NHaOH standard solution was added to the solution, warmed to boil and the blue colour disappeared, titrated rapidly with 1.0NNaOH standard solution to a stable cyperus malaccensis colour again, equivalent to Na per milliequivalent of standard NaOH solution₂Sif₄47.02mg, calculated as Na₂Sif₄The yield is that anhydrous Na is added into the filtrate according to the proportion of 1: 0.75₂SO₄Stirring for half an hour, and standing to separate out precipitate. After filtration, the precipitate was washed twice with waterAnd drying for four hours at 105 ℃ after centrifugal dehydration to obtain the finished product. The filtrate contains H₂SO⁺ ₄H capable of being consumed₂SO₄And the other soluble sulfate contained in the waste water is not harmful to the reaction.

Claims

1. The invention uses fluorite and quartz which are difficult to decompose as raw materials to produce sodium fluosilicate at normal temperature and normal pressure, and the prior case of producing sodium fluosilicate by the method is not available at present.

2. In the presence of a catalyst, the chemical reaction does not pass through HF and SiF₄Gaseous process, with formation of H directly in solution₂SiF₄. Then reacting with inorganic acid sodium salt to generate Na₂SiF₄。

3. In solution [ SiF₄]"Complex ion formation effectively reduces the F ion content of the solution below that of CaF₂The ion product concentration is the theoretical basis of the present invention.