冶金硅爐外精煉除磷的研究
發(fā)布時(shí)間：2018-09-11 15:38
【摘要】：隨著全球經(jīng)濟(jì)的發(fā)展,傳統(tǒng)能源日益枯竭和環(huán)境問題逐年加重,這使得世界各國開始大力發(fā)展新能源,其中太陽能因其分布廣泛、資源豐富、清潔無污染等優(yōu)點(diǎn),被認(rèn)為是21世紀(jì)最重要的新能源。在世界各國的政策積極扶持下,太陽能光伏產(chǎn)業(yè)迅速發(fā)展,使得對(duì)太陽能級(jí)多晶硅(SG-Si)的需求大增,但居高不下的生產(chǎn)成本制約了光伏產(chǎn)業(yè)的發(fā)展,因此研究高效率、低成本的太陽能級(jí)多晶硅的制備方法有著重大的現(xiàn)實(shí)意義。冶金法制備太陽能多晶硅具有能耗低、成本低、污染小等優(yōu)點(diǎn)。研究冶金法制備多晶硅對(duì)我國打破國際壟斷、擁有自主知識(shí)產(chǎn)權(quán)及發(fā)展我國光伏產(chǎn)業(yè)有著重要的戰(zhàn)略意義。本文主要以冶金級(jí)硅(MG-Si)為原料,從多方面入手研究硅中雜質(zhì)元素磷的去除。(1)研究發(fā)現(xiàn),P-Si合金中P是以SiP的形式存在。雜質(zhì)在固態(tài)的冶金級(jí)硅中呈深色、白色夾雜物的形式分布。夾雜物的化學(xué)組成表明,深色雜質(zhì)為熔渣型夾雜,而白色夾雜主要為金屬或金屬間化合物。P與硅中其他元素間的優(yōu)先結(jié)合順序?yàn)镃a3P2Mg3P2 MnP3Co2PAlPSiP。(2)加Ca還原精煉除磷實(shí)驗(yàn)研究。從熱力學(xué)上分析了加Ca還原精煉雜質(zhì)元素磷的去除形式：與加入硅中的Ca發(fā)生反應(yīng)生成Ca3P2,導(dǎo)致磷的固液分配系數(shù)減小,與CaSi2構(gòu)成第二相沉淀析出,再結(jié)合酸洗可以去除。以最佳精煉條件：精煉溫度為1813K,鈣硅質(zhì)量比為9.5%,對(duì)冶金硅進(jìn)行了除磷探究。精煉后,冶金硅中磷含量由94ppmw降到了15ppmw。(3)吹氣精煉除磷的研究。在精煉過程中,噴嘴類型能影響磷的去除率,在高純石墨管底部和側(cè)邊共有15個(gè)小孔的C型噴嘴為最優(yōu)。精煉溫度是冶金硅吹氣精煉主要的影響因素。高溫不利于熔硅中磷的去除,在精煉溫度為1793K,磷的去除率達(dá)到了88.30%,為最優(yōu)精煉溫度。精煉氣溫度的增加有利于熔硅中磷的去除。選擇精煉氣溫度為373K為最佳的工藝條件。氣流流速為2L/min,為最佳精煉氣流速。在最佳吹氣精煉條件下,冶金硅熔體中的磷元素由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.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TQ127.2
本文編號(hào)：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.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TQ127.2
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