Method for preparing high-purity silicon by high temperature gas-solid reaction

Abstract

The invention discloses a method for preparing high-purity silicon by using high temperature gas-solid reaction, which comprises the following steps: (1) taking low-purity silicon to be crushed, and then screening the low-purity silicon; (2) putting crushed silicon material into a high temperature solid phase reaction furnace, vacuumizing to be between 1.0*10 and 1.0*10Pa so as to remove most part of air inside the furnace, using inert gases to permute so as to remove air inside the furnace, increasing the temperature of the silicon material to be between 800 and 1412 DEG C, and charging active gases to perform the gas-solid reaction; and (3) cleaning the silicon material treated through the step (2) and obtaining the high-purity silicon product. The invention prepares the high-purity silicon by the gas-solid reaction, has high production efficiency, small investment on equipment, low energy consumption is low, great productivity, little influence on the environment, low cost, and high product purity, and can be further used for prepare the high-purity silicon used in the solar energy battery industry.

Description

technical field [0001] The invention belongs to the technical field of metal silicon purification, and in particular relates to a method for preparing high-purity silicon by utilizing high-temperature gas-solid reaction. Background technique [0002] In today's situation of increasingly tense energy and increasing environmental pressure, renewable energy has been paid more and more attention by governments of various countries. As an important renewable energy, solar energy, its development and utilization has become an important part of the sustainable development strategy of various countries. . At present, my country's renewable energy scale is only 8%, and the future development space is very broad. As the energy source with the most potential in the 21st century, the solar energy industry has made considerable progress in research and development, industrialization, and market development. The solar cell industry has also become one of the fastest and steadily developi...

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Problems solved by technology

[0003] There are many existing methods for directly purifying industrial silicon into higher-purity silicon, which can be summarized as acid leaching (also known as pickling) and oxidation refining. For example, the invention patent with application number 200710066017. , Crushing, ball milling, screening, preliminary impurity removal and other processes, put it into ultrasonic and microwave fields for metallurgical acid leaching treatment, and the metallurgical grade silicon powder after intensive treatment is combined with atmospheric pressure wet leaching and high temperature and high pressure leaching, The metal impurities in metallurgical grade silicon powder can enter the leaching solution as soon as possible. This method effectively improves the purity of silicon, but the method is long in process, high in energy consumption, and involves a large amount of acid solution; the invention patent with application number 200610124525.1 adopts vacuum induction In the smelting furnace, when the temperature reaches the melting point, a strong oxidizing gas (chlorine gas) is injected into the bottom of the crucible. The strong oxidizing gas reacts with impurity elements such as Fe-Al-Ca-P-V while stirring the silicon melt and vaporizes it. Then directional crystallization will be refined. This method has a certain effect on purification, but this method cannot allow the impurities in the silicon material to fully contact with the oxidizing gas, and cannot avoid the pollution of the crucible.

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