Method for preparing silicon tetrafluoride co-production with calcium fluoride by using fluosilicic acid and calcium carbide dust

A technology of silicon tetrafluoride and calcium fluorosilicate, applied in the direction of silicon halide compound, calcium/strontium/barium fluoride, halogenated silane, etc., can solve the problems of difficult removal of impurities, many by-products, low conversion rate, etc. Achieve the effect of low cost of raw materials, saving raw materials and solving environmental problems

Inactive Publication Date: 2012-10-03
DO FLUORIDE CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although there are several domestic companies producing SiF 4 , but most of the process methods used are traditional sulfuric acid method and Si-HF direct synthesis method. The common c...

Method used

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  • Method for preparing silicon tetrafluoride co-production with calcium fluoride by using fluosilicic acid and calcium carbide dust
  • Method for preparing silicon tetrafluoride co-production with calcium fluoride by using fluosilicic acid and calcium carbide dust
  • Method for preparing silicon tetrafluoride co-production with calcium fluoride by using fluosilicic acid and calcium carbide dust

Examples

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Embodiment 1

[0023] The method for preparing silicon tetrafluoride and co-producing calcium fluoride by using fluosilicic acid and calcium carbide, the specific steps are:

[0024] (1) 100g of calcium carbide and 815g of hydrochloric acid with a mass fraction of 10% were reacted at room temperature (25°C) for 6h, filtered and washed, and 35g of the wet filter residue was unreacted calcium chloride solution; After concentrating, the obtained mass fraction is 300g of calcium chloride solution of 40%;

[0025] (2) 300 g of calcium chloride solution with a mass fraction of 40% and 830 g of a fluorosilicic acid solution with a mass fraction of 15% were reacted for 5 hours at room temperature according to the molar ratio of calcium chloride to fluorosilicate acid 1.25:1.0, filtered and washed, filtered After the cake is dried, 150g of calcium fluosilicate is obtained, and the filtrate hydrochloric acid is recycled;

[0026] (3) pyrolyze 150g of calcium fluorosilicate at 300°C for 6 hours to obt...

Embodiment 2

[0030] The method for preparing silicon tetrafluoride and co-producing calcium fluoride by using fluosilicic acid and calcium carbide, the specific steps are:

[0031] (1) React 100 g of calcium carbide with 550 g of filtrate hydrochloric acid with a mass fraction of 15% at 50 ° C for 4 hours, filter and wash, and 32 g of wet filter residue is unreacted calcium chloride solution; the filtrate and washing liquid are calcium chloride solution, after concentration The obtained mass fraction is 280g of calcium chloride solution of 45%;

[0032] (2) 280g of calcium chloride solution with a mass fraction of 45% and 420g of a fluorosilicic acid solution with a mass fraction of 30% were reacted for 3 hours at room temperature according to the molar ratio of calcium chloride to fluorosilicate acid 1.3:1.0, filtered and washed, filtered After the cake is dried, 155g of calcium fluosilicate is obtained, and the filtrate hydrochloric acid is recycled;

[0033] (3) 155g of calcium fluoros...

Embodiment 3

[0037] The method for preparing silicon tetrafluoride and co-producing calcium fluoride by using fluosilicic acid and calcium carbide, the specific steps are:

[0038] (1) React 100 g of calcium carbide with 550 g of filtrate hydrochloric acid with a mass fraction of 15% at 100 ° C for 2 hours, filter and wash, and 30 g of wet filter residue is unreacted calcium chloride solution; the filtrate and washing liquid are calcium chloride solution, after concentration The obtained mass fraction is 250g of calcium chloride solution of 50%;

[0039] (2) 250 g of calcium chloride solution with a mass fraction of 50% and 315 g of a fluorosilicic acid solution with a mass fraction of 40% were reacted for 1 hour at room temperature according to the molar ratio of calcium chloride to fluorosilicate acid of 1.5:1.0, filtered and washed, filtered After the cake is dried, 157g of calcium fluosilicate is obtained, and the filtrate hydrochloric acid is recycled;

[0040] (3) 157g of calcium fl...

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Abstract

The invention discloses a method for preparing silicon tetrafluoride co-production with calcium fluoride by using fluosilicic acid and calcium carbide dust. The method disclosed by the invention comprises the following steps of: reacting the calcium carbide dust with hydrochloric acid at 5-100 DEG C to obtain a calcium chloride solution, and concentrating to obtain the calcium chloride solution with the mass percentage of 40-60%; then reacting the calcium chloride solution with the mass percentage of 40-60% with the fluosilicic acid to obtain calcium fluosilicate, wherein the filtrate hydrochloric acid is recyclable; thermally decomposing the dried calcium fluosilicate to obtain crude silicon tetrafluoride and calcium fluoride; condensing the crude silicon tetrafluoride, removing the dust and purifying to obtain highly pure crude silicon tetrafluoride. The method disclosed by the invention makes use of the by-product fluosilicic acid of phosphorous fertilizer and the calcium carbide dust with low added value to prepare the silicon tetrafluoride with high added value; the prepared calcium fluoride meets the standard of preparing acid-grade fluorite and can completely replace the strategic resource fluorite; the conversion rate of the raw material is high, the application field of the product is wide, and the efficient utilization of fluorine and silicon resources is realized completely. The method disclosed by the invention is remarkable in economical, environmental and social benefits.

Description

technical field [0001] The invention relates to the technical field of comprehensive utilization of industrial waste resources, in particular to a method for preparing silicon tetrafluoride and co-producing calcium fluoride by utilizing fluosilicic acid and calcium carbide. Background technique [0002] Fluorine chemical industry occupies an important position in the national economy. Fluorine chemical products are widely used in military industry, aerospace, chemical industry, machinery, ceramics, medicine and other fields. Fluorine chemical industry has become the fastest growing, most high-tech and most promising industry in the chemical industry. One of the industry, known as the 21st century "golden" industry. [0003] The main sources of fluorine in fluoride are fluorspar and phosphate rock. Fluorspar is a non-renewable resource. In order to protect fluorspar resources, the state implements a licensing system for the export of fluorspar. Making good use of fluorite r...

Claims

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Application Information

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IPC IPC(8): C01B33/107C01F11/22
Inventor 李世江侯红军杨华春李云峰李凌云于贺华薛旭金刘海霞王建萍刘陈红
Owner DO FLUORIDE CHEM CO LTD
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