Method for preparing polycrystalline silicon by reducing sodium fluosilicate with sodium
A technology of sodium fluorosilicate and polysilicon, which is applied in the field of preparing polysilicon by reducing sodium fluorosilicate with sodium, can solve the problems of polysilicon increasing equipment investment and energy consumption, and achieve the effects of saving equipment investment, reducing energy consumption, and low energy consumption
Inactive Publication Date: 2014-12-31
GUIZHOU PROVINCIAL PRODUCT QUALITY SUPERVISION AND INSPECTION INSTITUTE
View PDF15 Cites 0 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
However, sodium fluorosilicate is first decomposed and then reduced to obtain polysilicon, which undoubtedly increases equipment investment and energy consumption.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreExamples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0032] Take industrial sodium fluorosilicate with a mass fraction of 99.0%, dissolve it in hot water, filter to remove slag, cool the filtrate to room temperature, filter to obtain purified crystalline sodium fluorosilicate, and then use the purified crystalline sodium fluorosilicate to Purification by means of crystallization, repeated twice, to obtain sodium fluorosilicate with a purity greater than 99.99% in terms of mass fraction, and set aside;
[0033] The industrial sodium metal with a mass fraction of 99.5% is purified by vacuum vacuum distillation under the process conditions of pressure < 200Pa and temperature at 400°C to 800°C to obtain sodium metal with a purity greater than 99.999% in mass fraction for subsequent use;
[0034] Put the purified metal sodium and sodium fluorosilicate into the reaction kettle, and heat the reduction reaction at ≥600°C for 8 hours in a closed manner. After the reaction is completed, cool to room temperature; then mix the reaction produ...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
| Property | Measurement | Unit |
|---|---|---|
| quality score | aaaaa | aaaaa |
Login to View More
Abstract
The invention discloses a method for preparing polycrystalline silicon by reducing sodium fluosilicate with sodium. The method comprises the following steps of: (1) purifying sodium fluosilicate; (2) purifying metal sodium; (3) performing a reduction reaction; (4) performing first acid pickling; (5) performing second acid pickling; (6) performing third acid pickling; (7) washing with pure water; (8) drying filter cake. In the method, the reducing agent metal sodium is directly mixed with the sodium fluosilicate in the same reaction kettle, during the heating process, silicon tetrafluoride gas generated by decomposition of the sodium fluosilicate immediately reacts with the metal sodium to generate monatomic silicon and sodium fluoride, the process is finished in the same reaction kettle, thus, equipment investment is saved, energy consumption is lowered, and the energy consumption is lower than that of the existing technology of preparing polycrystalline by reducing sodium fluosilicate; the raw materials, metal sodium and sodium fluosilicate are purified firstly, and the possibility of bringing impurities into the final product silicon is reduced as much as possible, so that the polycrystalline silicon product can meet the high purity requirement. The method is suitable for the enterprises which produce polycrystalline silicon by using the phosphatic fertilizer by-product, namely the sodium fluosilicate, as the raw material.
Description
technical field [0001] The invention relates to a process for producing polysilicon, in particular to a method for preparing polysilicon by reducing sodium fluorosilicate with sodium. Background technique [0002] Polysilicon is the main raw material for the manufacture of silicon polished wafers, solar cells and high-purity silicon products, and is the most important and basic functional material for the semiconductor industry, electronic information industry, and solar photovoltaic cell industry. At present, the methods for preparing polysilicon mainly include improved Siemens method, silane thermal decomposition method, fluidized bed method, sodium reduction method and metallurgical method. The improved Siemens method is currently the most mature process for producing polysilicon, and the polysilicon produced accounts for 70% to 80% of the total production in the world today. The high cost of polysilicon products limits the popularization and application of polysilicon s...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/021
Inventor 张建刚黄春银刘少印高文龙程华鹏麻晖冯永渝
Owner GUIZHOU PROVINCIAL PRODUCT QUALITY SUPERVISION AND INSPECTION INSTITUTE