冶金硅炉外精炼除磷的研究
发布时间：2018-09-11 15:38
【摘要】：随着全球经济的发展,传统能源日益枯竭和环境问题逐年加重,这使得世界各国开始大力发展新能源,其中太阳能因其分布广泛、资源丰富、清洁无污染等优点,被认为是21世纪最重要的新能源。在世界各国的政策积极扶持下,太阳能光伏产业迅速发展,使得对太阳能级多晶硅(SG-Si)的需求大增,但居高不下的生产成本制约了光伏产业的发展,因此研究高效率、低成本的太阳能级多晶硅的制备方法有着重大的现实意义。冶金法制备太阳能多晶硅具有能耗低、成本低、污染小等优点。研究冶金法制备多晶硅对我国打破国际垄断、拥有自主知识产权及发展我国光伏产业有着重要的战略意义。本文主要以冶金级硅(MG-Si)为原料,从多方面入手研究硅中杂质元素磷的去除。(1)研究发现,P-Si合金中P是以SiP的形式存在。杂质在固态的冶金级硅中呈深色、白色夹杂物的形式分布。夹杂物的化学组成表明,深色杂质为熔渣型夹杂,而白色夹杂主要为金属或金属间化合物。P与硅中其他元素间的优先结合顺序为Ca3P2Mg3P2 MnP3Co2PAlPSiP。(2)加Ca还原精炼除磷实验研究。从热力学上分析了加Ca还原精炼杂质元素磷的去除形式：与加入硅中的Ca发生反应生成Ca3P2,导致磷的固液分配系数减小,与CaSi2构成第二相沉淀析出,再结合酸洗可以去除。以最佳精炼条件：精炼温度为1813K,钙硅质量比为9.5%,对冶金硅进行了除磷探究。精炼后,冶金硅中磷含量由94ppmw降到了15ppmw。(3)吹气精炼除磷的研究。在精炼过程中,喷嘴类型能影响磷的去除率,在高纯石墨管底部和侧边共有15个小孔的C型喷嘴为最优。精炼温度是冶金硅吹气精炼主要的影响因素。高温不利于熔硅中磷的去除,在精炼温度为1793K,磷的去除率达到了88.30%,为最优精炼温度。精炼气温度的增加有利于熔硅中磷的去除。选择精炼气温度为373K为最佳的工艺条件。气流流速为2L/min,为最佳精炼气流速。在最佳吹气精炼条件下,冶金硅熔体中的磷元素由94ppmw降低到11ppmw。
[Abstract]:With the development of the global economy, the traditional energy sources are increasingly exhausted and the environmental problems become more and more serious year by year, which makes the countries in the world develop new energy sources vigorously. Among them, solar energy is widely distributed, rich in resources, clean and pollution-free and so on. It is regarded as the most important new energy in the 21 st century. With the active support of the policies of various countries in the world, the solar photovoltaic industry is developing rapidly, which makes the demand for solar grade polysilicon (SG-Si) increase greatly, but the high production cost restricts the development of the photovoltaic industry, so the research is highly efficient. The preparation method of low-cost solar-grade polysilicon has great practical significance. The preparation of solar polysilicon by metallurgical method has the advantages of low energy consumption, low cost and low pollution. It is of great strategic significance to study the preparation of polysilicon by metallurgical process for China to break the international monopoly, possess its own intellectual property rights and develop the photovoltaic industry in China. In this paper, the removal of impurity phosphorus in silicon is studied from many aspects using metallurgical grade silicon (MG-Si) as raw material. (1) it is found that P in P Si alloy is in the form of SiP. Impurities are distributed in dark and white inclusions in solid metallurgical silicon. The chemical composition of the inclusions shows that the dark impurities are slag inclusions, while the white inclusions are mainly metal or intermetallic compounds. P preferentially binds to other elements in silicon. The experimental study on phosphorus removal by Ca3P2Mg3P2 MnP3Co2PAlPSiP. (2) plus Ca reduction refining is carried out. The removal form of phosphorus in reduction refining by adding Ca was thermodynamically analyzed. The reaction with Ca in silicon resulted in the reduction of solid-liquid partition coefficient of phosphorus, the precipitation of the second phase with CaSi2, and the removal of phosphorus by acid pickling. With the optimum refining conditions: refining temperature 1813 K, mass ratio of calcium to silicon 9.5, phosphorus removal of metallurgical silicon was studied. After refining, the phosphorus content in metallurgical silicon was reduced from 94ppmw to 15ppmw. (3) study on phosphorus removal by blowing refining. In the refining process, the type of nozzle can affect the removal rate of phosphorus, and the C-shaped nozzle with 15 holes at the bottom and side of the high-purity graphite tube is the best. Refining temperature is the main influencing factor of metallurgical silicon blowing refining. The high temperature is not conducive to phosphorus removal in molten silicon. At refining temperature of 1793 K, the removal rate of phosphorus reaches 88.30, which is the optimum refining temperature. The increase of refining gas temperature is beneficial to the removal of phosphorus in molten silicon. The optimum process condition is to select 373K as refining gas temperature. The gas flow rate is 2 L / min, which is the best refining velocity. Under the optimum condition of blowing gas refining, the phosphorus element in metallurgical silicon melt was reduced from 94ppmw to 11ppmw.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TQ127.2
本文编号：2237109
[Abstract]:With the development of the global economy, the traditional energy sources are increasingly exhausted and the environmental problems become more and more serious year by year, which makes the countries in the world develop new energy sources vigorously. Among them, solar energy is widely distributed, rich in resources, clean and pollution-free and so on. It is regarded as the most important new energy in the 21 st century. With the active support of the policies of various countries in the world, the solar photovoltaic industry is developing rapidly, which makes the demand for solar grade polysilicon (SG-Si) increase greatly, but the high production cost restricts the development of the photovoltaic industry, so the research is highly efficient. The preparation method of low-cost solar-grade polysilicon has great practical significance. The preparation of solar polysilicon by metallurgical method has the advantages of low energy consumption, low cost and low pollution. It is of great strategic significance to study the preparation of polysilicon by metallurgical process for China to break the international monopoly, possess its own intellectual property rights and develop the photovoltaic industry in China. In this paper, the removal of impurity phosphorus in silicon is studied from many aspects using metallurgical grade silicon (MG-Si) as raw material. (1) it is found that P in P Si alloy is in the form of SiP. Impurities are distributed in dark and white inclusions in solid metallurgical silicon. The chemical composition of the inclusions shows that the dark impurities are slag inclusions, while the white inclusions are mainly metal or intermetallic compounds. P preferentially binds to other elements in silicon. The experimental study on phosphorus removal by Ca3P2Mg3P2 MnP3Co2PAlPSiP. (2) plus Ca reduction refining is carried out. The removal form of phosphorus in reduction refining by adding Ca was thermodynamically analyzed. The reaction with Ca in silicon resulted in the reduction of solid-liquid partition coefficient of phosphorus, the precipitation of the second phase with CaSi2, and the removal of phosphorus by acid pickling. With the optimum refining conditions: refining temperature 1813 K, mass ratio of calcium to silicon 9.5, phosphorus removal of metallurgical silicon was studied. After refining, the phosphorus content in metallurgical silicon was reduced from 94ppmw to 15ppmw. (3) study on phosphorus removal by blowing refining. In the refining process, the type of nozzle can affect the removal rate of phosphorus, and the C-shaped nozzle with 15 holes at the bottom and side of the high-purity graphite tube is the best. Refining temperature is the main influencing factor of metallurgical silicon blowing refining. The high temperature is not conducive to phosphorus removal in molten silicon. At refining temperature of 1793 K, the removal rate of phosphorus reaches 88.30, which is the optimum refining temperature. The increase of refining gas temperature is beneficial to the removal of phosphorus in molten silicon. The optimum process condition is to select 373K as refining gas temperature. The gas flow rate is 2 L / min, which is the best refining velocity. Under the optimum condition of blowing gas refining, the phosphorus element in metallurgical silicon melt was reduced from 94ppmw to 11ppmw.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TQ127.2
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