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Method for preparing silicon tetrafluoride from phosphorus ore accompanied with fluorine

A technology of silicon tetrafluoride and water-containing silicon tetrafluoride, applied in the field of phosphorus chemical industry, can solve problems such as by-product fluorosilicate, and achieve the effects of reducing output, reducing manufacturing cost and reducing consumption

Active Publication Date: 2021-01-01
HUBEI XIANGYUN GROUP CHEM +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The purpose of the present invention is to overcome the technical defect of by-product fluorosilicate in the existing wet-process phosphoric acid production process, and provide a method that is more economical and effective, has wider application range, higher resource utilization rate and more energy saving

Method used

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  • Method for preparing silicon tetrafluoride from phosphorus ore accompanied with fluorine

Examples

Experimental program
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Effect test

Embodiment 1

[0043] Mix 410kg 90wt% sodium fluorosilicate (water content 10%), 540kg water, 60kg quartz sand into a slurry, slowly add 1360kg washing sulfuric acid (95wt%), react for 90min, the system exothermic violently to obtain hydrous silicon tetrafluoride Crude gas; washed and dehydrated by 1360kg of hot concentrated sulfuric acid (98wt%, 160°C) to obtain anhydrous silicon tetrafluoride gas, cooled to -18°C, and then pressurized to 0.2MPa, into the refined Distillation tower 1 extracts uncondensed silicon tetrafluoride gas from the top of the tower, then further cools to -70°C, pressurizes to 0.5 MPa, enters rectification tower 2, and extracts silicon tetrafluoride gas from the bottom of the tower. The recovery rate of fluorine was 94.3%.

Embodiment 2

[0045] Mix 210kg 90wt% sodium fluosilicate (water content 10%), 1000kg 12wt% fluosilicic acid and 70kg phosphoric acid production tail wash silica gel into a slurry, slowly add 2213kg washing sulfuric acid (95wt%), react for 60min, the system is violent Release heat to obtain crude silicon tetrafluoride gas containing water; wash and dehydrate with 2210kg hot concentrated sulfuric acid (98wt%, 90°C) to obtain anhydrous silicon tetrafluoride gas, cool the anhydrous silicon tetrafluoride gas to -5°C, and then Pressurize to 0.3MPa, enter rectification tower 1, extract uncondensed silicon tetrafluoride gas from the top of the tower, then further cool to -80°C, pressurize to 0.45MPa, enter rectification tower 2, and extract from the bottom of the tower silicon tetrafluoride. The recovery rate of fluorine was 92.8%.

Embodiment 3

[0047] Mix 288 kg 90wt% potassium fluosilicate (water content 10%), 1160kg 8wt% fluosilicic acid and 80kg diatomaceous earth into a slurry, slowly add 2692kg washing sulfuric acid (95wt%), react for 30min, and the system decomposes violently heat to obtain crude silicon tetrafluoride gas containing water; wash and dehydrate with 2700kg hot concentrated sulfuric acid (98%, 120°C) to obtain anhydrous silicon tetrafluoride gas, cool the anhydrous silicon tetrafluoride gas to -20°C, and add Pressure to 0.1MPa, enter rectification tower 1, extract uncondensed silicon tetrafluoride gas from the top of the tower, then further cool to -40°C, pressurize to 0.6MPa, enter rectification tower 2, and extract from the bottom of the tower Silicon tetrafluoride. The recovery rate of fluorine was 91.4%.

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Abstract

The invention discloses a method for preparing silicon tetrafluoride from phosphorus ore accompanied with fluorine, and belongs to the technical field of phosphorus chemical industry. The method comprises the following steps: (1) uniformly stirring silica gel generated by preparing phosphoric acid, a byproduct fluosilicic acid of silica gel phosphoric acid and fluosilicate obtained by reaction, and then adding washing sulfuric acid for reaction to obtain water-containing silicon tetrafluoride crude gas and sulfuric acid with the concentration of 70-80wt%, and using the sulfuric acid with the concentration of 70-80wt% for preparing phosphoric acid; (2) washing the water-containing silicon tetrafluoride crude gas obtained in the step (1) with hot concentrated sulfuric acid to obtain anhydrous silicon tetrafluoride crude gas, and sending the washed sulfuric acid to the step (1), wherein the concentration of the hot concentrated sulfuric acid is 90-105 wt%, and the temperature is 80-160 DEG C; (3) purifying the anhydrous silicon tetrafluoride crude gas obtained in the step (2) to obtain silicon tetrafluoride. The method has the advantages of being more economical and effective, wider in application range, higher in resource utilization rate and more energy-saving.

Description

technical field [0001] The invention relates to the technical field of phosphorus chemical industry, in particular to a method for preparing silicon tetrafluoride from fluorine associated with phosphate rock. Background technique [0002] Silicon tetrafluoride (SiF 4 ) Si atoms form σ bonds with sp3 hybrid orbitals, and the molecular shape is a regular tetrahedron. The fluorine-silicon bond has a relatively large bond energy, which reflects relatively special physical and chemical properties. It is one of the important chemical raw materials in the field of fluorine chemical industry. It is mainly used in the electronics and semiconductor industries as an etchant for silicon nitride, as a P-type dopant, as a source of epitaxially deposited diffused silicon, etc. It can also be used to prepare orthosilicate, electronic-grade silane or silicon. SiF 4 It can also be used as a raw material for high-purity quartz glass for optical fibers, and its hydrolysis in a high-temperatur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/107C01B25/222
CPCC01B33/10705C01B25/222Y02P20/10
Inventor 黄忠何俊余双强张险峰徐超陈喜珍查炎华
Owner HUBEI XIANGYUN GROUP CHEM