成果報告書詳細
管理番号20110000000840
タイトル*平成22年度中間年報 太陽エネルギー技術研究開発 太陽光発電システム次世代高性能技術の開発 太陽電池用シリコンの革新的プロセス研究開発(高純度原料の開発)
公開日2011/7/30
報告書年度2010 - 2010
委託先名太平洋セメント株式会社
プロジェクト番号P07015
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等
高純度結晶シリコン製造の要素技術として、平成22 年度は、国産天然シリカ原料から要求純度を満たすシリカの高純度化技術を確立することを目標とした。また、シリコン製造に必要となる高純度カーボン原料の調査も併せて実施した。
(1)シリカ原料の調合技術の開発
国産天然シリカ原料から効率的なシリカの回収方法を検討した。はじめに、国産天然シリカ原料の各種キャラクタリゼーションを行い、主要構成鉱物がアモルファスシリカ(Opal-CT)、トリジマイト、石英、スメクタイト、長石であること(図1)、アモルファスシリカの含有量が約40~70%であることを確認した。
国産天然シリカからアモルファスシリカを回収するには,アルカリ性溶液で処理する必要がある。そこで、上述の知見を基に、国産天然シリカ原料のアルカリ溶解条件等を適正化した後、アモルファスシリカの回収(シリカゾルとして回収)を実施した(図2)。その結果、アルカリ溶解条件は常圧下で溶解温度70℃以下となり,従来のガラスカレットからシリカゾルを製造する工程に比べて,省エネ化できることを見出した。また、同条件下でアモルファスシリカを90%以上回収できることを確認した。
英文要約Title: R&D of solar energy technology/Development of next-generation high-performance technology for photovoltaic power generation system/R&D of innovative silicon processing for solar cells/Development of high-purity materials (FY2010 - FY2012) FY2010 Annual Report
1. R&D description and outcome: The goal for FY2010 is to establish a technology for turning natural silica minerals of domestic production into high-purity silica that meets purity requirements as a component technology for manufacturing high purity crystalline silicon. Research on high purity carbon materials, required for silicon manufacturing, has also been conducted. (1)Developing a technology for preparing silica minerals: The method for efficiently collecting silica from domestic natural silica minerals has been explored. Firstly, domestic natural silica minerals was characterized to find that they mainly consist of amorphous silica (Opal-CT), tridymite, quartz, smectite and feldspar, and that their amorphous silica content was approx. 40 - 70%. Collecting amorphous silica from domestic natural silica minerals requires treatment with alkali solution. Based on the aforementioned knowledge, domestic natural silica minerals had their alkali dissolving condition optimized before amorphous silica was collected (as silica sol). The alkali dissolving temperature was 70 degrees Celsius or below at normal pressure, which provides energy saving compared to the conventional approach of manufacturing silica sol from glass cullet. It was also confirmed that, under this condition, over 90% of amorphous silica was recovered. (2)Developing a technology for obtaining high purity silica: The method for recovering silica from the silica sol obtained in the aforementioned process and refining it to high purity has been explored, with a view to improve silica's recovery rate and reduce the presence of impurities. For even greater reduction of impurities, the approach to clean recovered silica with acid or water was considered to optimize treatment conditions for obtaining high purity silica. As a result, the rate of silica recovery in the newly-developed method was 80%, far exceeding the existing approach's performance (20%). This would also eliminate the need for expensive organic materials. Soaking extracted silica in sulfuric acid at 70 degrees Celsius for one day, and washing it with water repeatedly, have successfully produced high purity silica (B, P=1ppm or below) without having to use expensive hydrochloric acid. (3)Consideration for obtaining high purity carbon materials (re-commissioned to Tokai Carbon Co., Ltd.): The approach to obtain various carbon materials was explored. Existing carbon materials were screened to identify the effect of refining treatment. This consequently found carbon with the B and P content of 1ppm or below. It has been confirmed that treating this to achieve high purity can also reduce the content of main elements other than B and P to 1ppm or below.
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