本文關(guān)鍵詞： 冶金硅 合金精煉 造渣法 硼雜質(zhì)　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：能源危機(jī)帶來的諸多問題導(dǎo)致依賴傳統(tǒng)能源的能源結(jié)構(gòu)必須進(jìn)行改革,應(yīng)運(yùn)而生的新能源因?yàn)榫哂锌裳h(huán)無污染綠色環(huán)保等優(yōu)點(diǎn)有望取代傳統(tǒng)能源。太陽能因?yàn)閮α看蟆㈤_采方便、無地域限制、清潔無污染等優(yōu)點(diǎn)使其能超越風(fēng)能、水能、地?zé)崮艿瘸蔀闃O具潛質(zhì)且未來可廣泛高效應(yīng)用的清潔能源。太陽能電池是實(shí)現(xiàn)光電轉(zhuǎn)化的主要裝置,硅料因?yàn)閮α看蟆⒐怆娹D(zhuǎn)化效率高、性能穩(wěn)定等優(yōu)點(diǎn)占據(jù)太陽電池原材料的絕大部分市場,硅太陽能電池的原料以多晶硅為主。初期硅的提純主要依賴以西門子法為代表的化學(xué)法,其能耗高,設(shè)備復(fù)雜,且產(chǎn)品純度不適用于太陽能電池,冶金法可以解決這些問題,此方法能耗低,提純溫度低,設(shè)備構(gòu)造簡單且成本低,有利于工業(yè)化生產(chǎn)。本文研究利用合金精煉-造渣法提純冶金硅,通過結(jié)合合金精煉提純法和造渣提純法來研究低溫條件下硼的去除,以改變傳統(tǒng)造渣法在高溫條件下的高能耗問題,從而真正實(shí)現(xiàn)低能耗、低成本去除冶金硅中硼雜質(zhì)。本文通過對M-Si合金體系結(jié)合造渣法進(jìn)行實(shí)驗(yàn),通過改變合金組成、渣劑種類、熔煉時間、渣金比以及堿度,研究不同實(shí)驗(yàn)條件對除硼效果的影響,主要得到以下結(jié)論：(1)采用Si-Sn合金以及Na2SiO3-CaO-SiO2渣劑進(jìn)行精煉提純,隨著Sn添加量的增大,渣金比的增大,熔煉時間的增加,硅中硼雜質(zhì)含量逐漸降低,硼的去除率逐漸增大,Sn添加量為50at%時,經(jīng)過一次造渣,硅中的硼含量由初始值12.92ppmw降至0.786ppmw,去除率為93.92%；在渣金比達(dá)到1.75：1之后硅中的硼含量基本達(dá)到穩(wěn)定狀態(tài)；(2)采用Si-Sn合金以及Na2CO3-SiO2渣劑進(jìn)行精煉提純,隨著熔煉時間的增加,Sn添加量的增大,渣金比的增大,硅中硼含量表現(xiàn)出逐漸降低的趨勢；當(dāng)Sn添加量為50at%時,經(jīng)過一次造渣,硅中的硼含量降至0.9ppmw,去除率為93.03%；在渣金比達(dá)到1.25：1之后硅中的硼含量基本達(dá)到穩(wěn)定狀態(tài)；隨著堿度的增加,硅中的硼含量先降低后增加,這主要是因?yàn)榕鸬娜コ茉鼊〾A度以及氧分壓的雙重影響,當(dāng)渣劑堿度較小時,堿度是制約反應(yīng)的主要因素,當(dāng)堿度較大時,氧分壓成為制約反應(yīng)的主要因素。(3)采用Al-Si合金以及Na3AlF6-Al2O3渣進(jìn)行精煉提純,渣劑的引入對Al-Si合金精煉除硼的效果有一定的強(qiáng)化作用,與同時間的合金精煉效果相比,引入造渣過程后,除硼效率能夠提高15.7%。雜質(zhì)硼含量降低至2.85ppmw。同時,熔煉時間對除硼效果也有較大影響,隨著熔煉時間的增加,初晶硅中雜質(zhì)硼含量逐漸降低,去除率逐漸增加。分析合金精煉-造渣法對Al-Si合金除B過程的影響,硼原子在渣劑及金屬中的溶解度不同所引起的分配系數(shù)及渣劑揮發(fā)過程可能是強(qiáng)化雜質(zhì)硼去除的主要原因。
[Abstract]:Many problems brought about by the energy crisis have led to the reform of the energy structure that depends on traditional energy sources. The new energy, which has the advantages of recycling, pollution-free, green and environmental protection, is expected to replace traditional energy sources. The advantages of easy exploitation, no geographical restriction, clean and pollution-free make it possible to surpass wind, water and geothermal energy to become a potential clean energy source which can be widely and efficiently used in the future. Solar cells are the main devices to realize photovoltaic conversion. Because of its large reserves, high photoelectric conversion efficiency and stable performance, silicon occupies the vast majority of the market of raw materials for solar cells. Polysilicon is the main raw material for silicon solar cells. In the initial stage, the purification of silicon mainly depends on the chemical method represented by Siemens method. Its energy consumption is high, the equipment is complex, and the product purity is not suitable for solar cells. Metallurgical method can solve these problems. This method has the advantages of low energy consumption, low purification temperature, simple structure and low cost. Boron removal under low temperature is studied by combining alloy refining and slag purification to change the problem of high energy consumption in the traditional slag making process at high temperature so as to realize the real low energy consumption. Removal of boron impurities from metallurgical silicon at low cost. In this paper, the effects of different experimental conditions on the effect of boron removal were studied by changing the composition of the alloy, the type of slag, the melting time, the ratio of slag to gold and the alkalinity through the experiments on M-Si alloy system combined with slagging method. The main conclusions are as follows: (1) Si-Sn alloy and Na2SiO3-CaO-SiO2 slag are used for refining and purification. With the increase of Sn content, the ratio of slag to gold, the melting time, the boron impurity content in silicon decreases gradually. When the removal rate of boron is increasing gradually, the content of tin is 50 at%, and after primary slagging, The boron content in silicon decreases from 12.92 ppmw to 0.786ppmw, the removal rate is 93.92pmw, and the boron content in silicon reaches stable state after the ratio of slag to gold reaches 1.75: 1. The boron content in silicon is refined and purified by Si-Sn alloy and Na2CO3-SiO2 slag agent. With the increase of smelting time, the content of Sn is increased. With the increase of slag / gold ratio, the content of boron in silicon decreases gradually, when the content of Sn is 50 at%, the content of boron in silicon decreases to 0.9ppmwand the removal rate is 93.030.When the ratio of slag to gold reaches 1.25: 1, the content of boron in silicon basically reaches a stable state. With the increase of alkalinity, the content of boron in silicon decreases first and then increases. This is mainly because the removal of boron is affected by the alkalinity of slag agent and the partial pressure of oxygen. When the alkalinity of slag agent is small, alkalinity is the main factor restricting the reaction, and when the alkalinity is large, Oxygen partial pressure is the main factor restricting the reaction. (3) Al-Si alloy and Na3AlF6-Al2O3 slag are used to refine and purify. The introduction of slag agent can strengthen the refining effect of Al-Si alloy, compared with the refining effect of the alloy at the same time. The boron removal efficiency can be increased by 15.7ppmw. the boron content of impurity decreases to 2.85ppmw. at the same time, the boron content in primary silicon decreases with the increase of smelting time. The effect of alloy refining and slag making on the process of removing B from Al-Si alloy was analyzed. The distribution coefficient and volatilization process of boron atoms in slag and metal due to the different solubility of boron atoms may be the main reasons for enhancing the removal of impurity boron.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN304.12

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本文編號：1506293