Application of byproducts in preparation of silane through magnesium silicide process

A by-product, magnesium silicide technology, applied in the preparation/separation of ammonia, silicon hydride, chlorine/hydrogen chloride, etc., can solve the problems of large pollution, high energy consumption, and large recovery consumption, and achieve the effect of reducing costs

Inactive Publication Date: 2011-04-27
鲍坚仁 +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The two methods have their own advantages and disadvantages: the silicothermal method requires less investment in equipment, but has high energy consumption and high pollution; while the electrolysis method has low energy consumption and low pollution but requires more equipment investment
In addition, the electrolytic method usually encounters two problems: 1. MgCl 2 Dehydration is required before electrolysis, but dehydration is very difficult; 2. How to recycle the by-products obtained by electrolysis: chlorine gas
This requires both increased investment and high energy consumption for dehydration and chlorine recovery

Method used

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  • Application of byproducts in preparation of silane through magnesium silicide process
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  • Application of byproducts in preparation of silane through magnesium silicide process

Examples

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Effect test

Embodiment 1

[0045] After weighing, 10mol Mg 2 Put Si into anhydrous liquid ammonia, keep the temperature of liquid ammonia at minus 30°C under one atmospheric pressure, and gradually and slowly introduce 40mol of anhydrous HCl, and after one hour of full reaction, gaseous SiH can be obtained 4 , and MgCl will be precipitated at the same time 2 6NH 3 By-products, the above reaction is carried out in an anhydrous closed environment. After taking out the by-products, after two hours of heating at 500°C, it decomposes to obtain anhydrous MgCl 2 and NH 3 gas, for MgCl 2 After weighing, it can be confirmed that it is 20mol of anhydrous MgCl 2 .

[0046] Anhydrous MgCl 2 Through molten electrolysis, the melting temperature is 950-1000°C, metal Mg can be obtained at the cathode, and 20mol of anhydrous Cl can be produced at the anode 2 .

[0047] The obtained 20mol of Cl 2 and 20mol of H 2 40 mol of anhydrous HCl that can be obtained through combustion reaction, after cooling to room te...

Embodiment 2

[0049] The metal magnesium powder obtained by electrolysis in Example 1 reacts with industrial silicon powder at high temperature to generate magnesium silicide Mg 2 Si, the reaction needs to be carried out in an atmosphere of hydrogen or argon, and the reaction temperature ranges from 600 to 1100°C. The amounts of metallic magnesium and industrial silicon are 20mol and 10mol respectively. There may be a small amount of loss or insufficient reaction in this reaction, and it may be necessary to increase the reactants as appropriate. get Mg 2 After Si, proceed according to the steps in Example 1. In this reaction, metal magnesium is recycled, and the product generated in the whole process is silane, and the raw materials that need to be supplemented are industrial silicon and hydrogen.

Embodiment 3

[0051] In the electrolytic magnesium industry, since the raw material MgCl is usually obtained 2 Both contain a large amount of crystal water, and dehydration must be carried out before the electrolysis of magnesium. One of the processes is to use ammonia for dehydration, which was first used by Nalco Chemical Company of the United States. The main idea is to use anhydrous ammonia, first by MgCl 2 ·6H 2 O to obtain MgCl 2 6NH 3 , and then deamination to obtain anhydrous and ammonia-free MgCl 2 , and then used in electrolysis, the specific process can be found on page 201 of "Magnesium Electrolysis Production Technology" edited by Zhang Yongjian. This process illustrates that MgCl 2 Ammonia removal is much easier than dehydration.

[0052] In obtaining anhydrous and ammonia-free MgCl 2 Afterwards, the steps described in Example 1 can be incorporated into the process cycle step. First electrolysis to obtain metal magnesium and Cl 2 , Cl 2 and H 2 Combustion to get HCl...

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Abstract

The invention provides an application of byproducts in the preparation of silane through magnesium silicide process, i.e. the process for joint production of the silane and metal magnesium is further provided by using the byproducts in the preparation of the metal magnesium through the electrolysis process and the preparation of the magnesium through the electrolysis process in the magnesium silicide process in a circulating manner. In the application of the byproducts in the preparation of the silane through the magnesium silicide process, the byproduct which is magnesium chloride in the preparation of the silane through the magnesium silicide process is used in the electrolysis process for preparing the metal magnesium. The byproduct which is chlorine gas and got during the process of preparing the metal magnesium through the electrolysis process is further burned with hydrogen, then anhydrous hydrogen chloride is got, and the anhydrous hydrogen chloride further becomes raw material for preparing the silane through the magnesium silicide process. The byproducts in the two processes of preparing the silane through the magnesium silicide process and preparing the magnesium through the electrolysis process in the joint production are the raw materials for each other, thereby reducing the cost and simultaneously reducing the pollution.

Description

technical field [0001] The invention relates to a use of by-products prepared by magnesium silicide method for preparing silane: metal magnesium is prepared by electrolysis, and the by-products of electrolytic magnesium production are recycled for magnesium silicide method, and a joint production process of silane and metal magnesium is proposed. Background technique [0002] In recent years, with the development of the solar cell industry, the demand for polysilicon has been driven up. The manufacturing technology of polysilicon mainly includes two processes: Siemens method and silane method. Internationally, polysilicon technology is monopolized by several large companies in the United States, Japan, Germany and other countries, and the technology blockade is very severe. In recent years, China's polysilicon technology has made great progress, but the import volume of polysilicon is still very large. [0003] The main by-product of the Siemens process is silicon tetrachlo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/04C25C3/04C01C1/02C01B7/01
Inventor 鲍坚仁鲍坚斌朱泽华
Owner 鲍坚仁
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