Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Method for removing boron and phosphorus impurity in industrial silicon by slagging refining

An industrial silicon and slag-making technology, which is applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problem of high dosage of slag aids (as little as a few ppm, as many as tens of ppm) and limit large-scale Production and other issues, to achieve the effect of simple process and high industrial feasibility

Inactive Publication Date: 2013-03-06
XIAMEN UNIV
View PDF11 Cites 13 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Many attempts have been made on the selection of slagging agents, and the common slag systems are CaO-SiO 2 , Na 2 O-SiO 2 , CaO-SiO 2 -CaF 2 , CaO-MgO-SiO 2 , CaO-BaO-SiO 2 etc. These slag systems have certain effects in the removal of B, but there are some unavoidable problems in industrial production: first, the removal effect of B is still difficult to meet the requirements of solar grade polysilicon
Secondly, the amount of slag aid used in the slagging process is relatively high, which limits large-scale production and will also cause some pollution to silicon
However, when using the CaO slagging system, the phosphorus content in the slagging agent is generally high (a few ppm at most, tens of ppm at most). After refining, phosphorus impurities are often more or less increased, which increases the difficulty of subsequent processes. Or increase the cost of impurity removal and purification

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 more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for removing boron and phosphorus impurity in industrial silicon by slagging refining

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] 1. Coat a dense SiC coating on the surface of the graphite crucible as an inner layer with a thickness of about 1.5mm, and then coat the SiC coating with Y 2 o 3 The thickness of the coating as the outer layer is about 1 mm to increase the service life of the graphite crucible.

[0038] 2. Weigh Fe 2 o 3 (10%wt)-SiO 2 (60%wt)-MnO(20%wt)-CaF 2 (10%wt) total 130kg of slagging agent, put into the coated graphite. Close the furnace cover, turn on the intermediate frequency, the power rises to 120kW within 1 hour, and keep the power at 120kW to completely melt the slag.

[0039] 3. After the slag is melted, add 25kg of industrial silicon (the B content is 8.6ppmw, and the P content is 15ppmw). After the slag and silicon materials are completely melted, reduce the power to 90kW within 25 minutes, and the reaction temperature at this time is 1550°C as measured by an infrared thermometer.

[0040] 4. Introduce the mixed gas Ar+H into the system 2 O, the ventilation rod ...

Embodiment 2

[0045] Technological process is with embodiment 1. Graphite crucible SiC inner coating thickness is 3mm, Y 2 o 3 The thickness of the outer coating is 1.5mm, and the slagging agent FeO(10%wt)-SiO is added to it 2 (60%wt)-MnO(15%wt)-CaF 2 (15%wt) 100kg in total. Turn on the intermediate frequency, increase the power to 150kW within 1.5h, and keep the power at 150kW to completely melt the slag. Then add 45kg industrial silicon. Reduce the power to 120kW within 15 minutes after complete melting, and the reaction temperature is 1650°C at this time. Pass 90%Ar+10%H 2 O Stir the melt, the distance between the aeration rod and the bottom of the crucible is about 12mm, and the aeration rate is 1L / min. After 15 minutes of slagging, pour the upper layer of silicon liquid into a graphite mold with an outer radius of 22cm, an inner radius of 20cm, and a height of 50cm for cooling. The cooling rate is controlled at 200°C / min. Add 45kg of industrial silicon again, adding 15 times in...

Embodiment 3

[0047] Technological process is with embodiment 1. Graphite crucible SiC inner coating thickness is 1mm, Y 2 o 3 The thickness of the outer coating is 2mm and the slagging agent Fe is added 3 o 4 (15%wt)-SiO 2 (60%wt)-MnO(10%wt)-CaF 2(15%wt) 100kg in total. Turn on the intermediate frequency, increase the power to 130kW within 1.2h, and keep the power at 130kW to completely melt the slag. Then add 35kg industrial silicon. Reduce the power to 110kW within 15 minutes after complete melting, and the reaction temperature at this time is 1750°C. The distance between the ventilation rod and the bottom of the crucible is 14mm, and the ventilation rate is 1.5L / min. After 20 minutes of slagging, pour the upper layer of silicon liquid into a graphite mold with an outer radius of 20cm, an inner radius of 18cm, and a height of 45cm for cooling. The cooling rate is controlled at 300°C / min. Add 35kg of industrial silicon again, adding 10 times in total. A total of 212kg of refined...

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

PropertyMeasurementUnit
thicknessaaaaaaaaaa
thicknessaaaaaaaaaa
radiusaaaaaaaaaa
Login to View More

Abstract

The invention discloses a method for removing the boron and phosphorus impurity in industrial silicon by slagging refining, and relates to the industrial silicon impurity removal technology. The method comprises the following steps of: 1) coating a compact SiC coating as an inner layer on the surface of a graphite crucible, and coating a Y2O3 coating on the SiC coating as an outer layer; 2) after slagging constituent is mixed, putting into a pre-processed graphite crucible; 3) opening a medium-frequency induction furnace for heating until slag charges are molten; 4) after the slag charges are molten, adding the industrial silicon into the molten slag charges, carrying out slagging refining, and reacting if power is lowered after the slag charges and silicon materials are totally molten; 5) inserting a venting pin into the molten liquid, and introducing Ar+H2O into the system to guarantee that the silicon and the slags are contacted; 6) pulling out the venting pin, and pouring the upper layer of silicon liquid of the molten liquid into a standing graphite module for cooling; 7) continuously adding silicon materials, and repeating steps 4) to 6); and 8) cutting impurity enrichment parts on the tail part and the head part of refined polysilicon, and measuring the content of residual parts of boron and phosphorus by ICP-MS (inductively coupled plasma-mass spectrum). The method has the advantages of simple technology and high industrial feasibility.

Description

technical field [0001] The invention relates to an impurity removal process for industrial silicon, in particular to a method for removing boron and phosphorus impurities in industrial silicon by slagging and refining. Background technique [0002] In today's world, the energy crisis and the pressure of environmental pollution coexist, and people urgently need clean, safe and sustainable new energy. As an energy source that meets such requirements, solar energy has always been the goal pursued by people. The earliest use of solar energy is the utilization of its thermal effect, but it is difficult to fully meet the needs of modern society. Until the discovery of the semiconductor photoelectric effect and the manufacture of solar cells, people found new ways to use solar energy. Silicon is the most ideal raw material for solar cells. The impurities in it mainly include metal impurities such as Fe, Al, and Ca and non-metallic impurities such as B and P. These impurity elemen...

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
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 罗学涛吴浩李锦堂余德钦林彦旭卢成浩
Owner XIAMEN UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com