本文關(guān)鍵詞：冶金級硅熔渣精煉深度除硼研究　出處：《昆明理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 冶金級硅 熔渣精煉 除硼 擴(kuò)散系數(shù) 傳質(zhì)系數(shù)

【摘要】：隨著全球能源消耗增加,太陽能光伏迅速發(fā)展,現(xiàn)已成為新能源行業(yè)中的重要部分。太陽能級多晶硅是生產(chǎn)制造太陽能電池的重要原料。冶金法由于成本低、能源消耗低、對環(huán)境污染小等優(yōu)點(diǎn),已成為制備太陽能級多晶硅的重要方法。冶金級硅中硼、磷以及其他雜質(zhì)的去除是冶金法面臨的重要課題。太陽能級多晶硅對于雜質(zhì)硼的要求是低于0.3ppmw,因為硼會降低少子壽命,從而影響太陽能電池的光電轉(zhuǎn)換效率。本論文以冶金級硅中雜質(zhì)硼的深度去除為研究目的,通過兩種新型三元熔渣CaO-SiO2-ZnCl2和CaO-SiO2-Zn0來探索熔渣精煉除硼的最優(yōu)實(shí)驗條件。還對B203在CaO-SiO2二元熔渣中的擴(kuò)散傳質(zhì)問題進(jìn)行實(shí)驗研究,明確了造渣除硼過程的限制性環(huán)節(jié)。利用CaO-SiO2-ZnCl2和CaO-SiO2-ZnO三元系作為造渣劑,分別在電阻爐和感應(yīng)爐中對冶金級硅進(jìn)行精煉除硼實(shí)驗。結(jié)果表明:(1)在電阻加熱條件下,對于CaO-Si02-ZnCl2渣系,20%ZnCl2添加量時除硼效果最好,可將硼含量降低到11.95ppmw;對于CaO-SiO2-Zn0渣系,10%ZnO添加量時除硼效果最好,可將硼含量降低到7.51ppmw。兩種渣系的除硼效果都隨渣硅比的增加而增強(qiáng),當(dāng)渣硅比為2:1時除硼效果最好,硼含量分別降低到7.92ppmw和12.09ppmw。精煉時間為3h時,兩種渣系可以分別將雜質(zhì)硼去除至8.91ppmw和8.02ppmw。精煉溫度為1823K時,硼含量分別降低到11.95ppmw和13.41ppmw。(2)在電磁感應(yīng)加熱條件下,46%CaO-46%SiO2-8%ZnO熔渣可以將硅中硼含量從12.94ppmw降低至2.18ppmw。通過酸洗可以使硅中硼含量進(jìn)一步降低至1.52ppmw,去除率提高到88.25%。(3)精煉硅中殘留鋅經(jīng)過酸洗以后可進(jìn)一步降低至4ppmw;通過真空蒸餾處理以后精煉硅中的鋅可以降低至0.05ppmw。利用毛細(xì)管-熔池擴(kuò)散裝置對B203在37%Ca0-63%Si02二元熔渣中的擴(kuò)散系數(shù)進(jìn)行了實(shí)驗測定。并根據(jù)37%Ca0-63%Si02二元熔渣精煉實(shí)驗結(jié)果計算了 B203在二元熔渣中的傳質(zhì)系數(shù),從而得到了反應(yīng)界面與熔渣間的邊界層厚度。結(jié)果表明:在1723K溫度下,在4mm孔徑石墨毛細(xì)管中擴(kuò)散30min后,B203在37%Ca0-63%SiO2渣中的擴(kuò)散系數(shù)為5.265×10-9m2/s。利用37%CaO-63%Si02熔渣在直徑為35mm的剛玉坩堝中對冶金級硅進(jìn)行造渣精煉,可以得到B203在37%Ca0-63%SiO2熔渣中的傳質(zhì)系數(shù)為6.2×10-6 m/s。渣硅反應(yīng)界面和熔渣一側(cè)的有效邊界層厚度為0.849mm。由此發(fā)現(xiàn)B203在熔渣中傳質(zhì)過程是熔渣精煉除硼的限制性環(huán)節(jié)。
[Abstract]:With the global increase in energy consumption, the rapid development of solar photovoltaic, has become an important part of the new energy industry. Solar grade polysilicon production is an important raw material for manufacturing a solar cell. The metallurgical method because of low cost, low energy consumption, little pollution, has become an important method for preparation of solar grade silicon from metallurgical grade silicon. In the removal of boron, phosphorus and other impurities is an important subject in metallurgy face. Solar grade polysilicon is lower than 0.3ppmw for the impurity boron requirements, because boron will reduce the lifetime, thus affecting the photoelectric conversion efficiency of solar cell. In this paper, boron impurities in metallurgical grade silicon removal depth for the purpose of the study by two new three yuan slag CaO-SiO2-ZnCl2 and CaO-SiO2-Zn0 to explore the optimal experimental conditions of boron slag in refining. The diffusion B203 in CaO-SiO2 two yuan in the slag. The experimental study, the slagging boron restricted link process. Using CaO-SiO2-ZnCl2 and CaO-SiO2-ZnO three series as slag, respectively of metallurgical grade silicon on resistance furnace and induction furnace refining experiment of boron removal. The results showed that: (1) under the condition of heating resistance, for CaO-Si02-ZnCl2 slag system, adding amount 20%ZnCl2 when the boron removal effect is the best, the boron content was reduced to 11.95ppmw; for CaO-SiO2-Zn0 slag system, 10%ZnO adding boron removal effect is best, can be reduced to the boron content of boron removal efficiency of 7.51ppmw. two kinds of slag are increased with the increase of the ratio of silicon slag increases, when the silicon slag ratio was 2:1 boron removal the best effect, the boron content were reduced to 7.92ppmw and 12.09ppmw. refining time of 3H, two kinds of slag can respectively be boron removal to 8.91ppmw and 8.02ppmw. refining temperature is 1823K, the boron content were reduced to 11.95ppmw and 13.41ppmw. (2) in electrical The magnetic induction heating conditions, 46%CaO-46%SiO2-8%ZnO slag can be boron content in silicon is reduced from 12.94ppmw to 2.18ppmw. by pickling can make silicon boron content further reduced to 1.52ppmw, the removal rate increased to 88.25%. (3) after pickling after zinc refining can be further reduced to 4ppmw residues in silicon; by vacuum distillation after processing in silicon zinc refining can be reduced to 0.05ppmw. by capillary - pool diffusion device was measured on the diffusion coefficient of B203 in 37%Ca0-63%Si02 of two yuan in the slag. The mass transfer coefficient and refining experimental results to calculate B203 in two yuan in two yuan according to the 37%Ca0-63%Si02 slag slag, thus obtained the thickness of boundary layer and the interface reaction between the slag. The results showed that: at the temperature of 1723K, 30min in 4mm graphite capillary pore diffusion after the diffusion coefficient of B203 in 37%Ca0-63%SiO2 slag is 5.265 * 10-9m2/s. by 37% CaO-63%Si02 slag in diameter of corundum crucible 35mm in metallurgical grade silicon slag refining, mass transfer coefficients can be obtained in B203 37%Ca0-63%SiO2 in the slag for the boundary layer thickness of 6.2 * 10-6 m/s. silicon slag and slag on the side of the interface reaction of 0.849mm. which found mass transfer in slag B203 slag removal is the limiting step of boron refining.

【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN304.12

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