• 作者： 林正雄; 余承聖
• 作者服務機構： 國立清華大學材料科學研究所
• 中文摘要： 本實驗使用鹽酸－溶媒除鐵法從低品位鐵礬士（簡稱三水鋁土）提煉氧化鋁，首先使三水鋁
  土?燒，氧化三水鋁土中之二價鐵離子，再用鹽酸浸漬此三水鋁土，抽出其中之氧化鋁，但
  水三鋁土中之氧化鐵也同時溶解出來，使得浸漬液內含有鐵及鋁離子。為除去浸漬液內之鐵離
  子，本實驗使用溶劑萃取法除去鐵離子，再使純化之浸漬液濃縮，加熱分解即得氧化鋁，另得副
  產品鹽酸同收循環使用。經過萃取鐵離子後之溶媒用純水清洗，鐵離子被水洗去，溶媒又被再生
  循環使用。
  本實驗發現為使三水鋁土中二價鐵氧化，充空氣?燒是必要的。為使二價鐵能充分氧化，最
  佳的?燒溫度為500～700℃之間，雖然在此溫度?燒氧化鋁抽出率稍微降低。當20％鹽酸之
  使用為恰足量時，氧化鋁之抽出率在95％以上，氧化鐵之抽出率為90％以上。當鹽酸之使用為
  50％足量，則氧化鋁、氧化鐵之抽出率皆降低，但氧化鐵之降低較快，結果用此方法可用來作為
  鐵和鋁之初步分離。
  三丁基磷酸酯溶媒之除鐵能力和浸漬液的酸度、鐵離子濃度及氯離子濃度有關。適當的酸度
  配合鐵離子濃度，在愈多的氯離子濃度下，鐵之分佈係數愈大，當酸度、鐵離子濃度及氯離子濃
  度配合時，可將浸漬液內之鐵離子全部去除，使所得氧化鋁純度合乎標準。
  本實驗另研究TBP溶媒的反萃取，亦即用水清洗除去鐵離子，以再生TBP溶媒循環使
  用，結果發現以6倍於TBP體積的水即可清洗除去TBP溶媒內的鐵離子。
  本實驗最後研究鹽酸浸清液反覆的使用，從三水鋁土提煉氧化鋁時，鹽酸內雜質的堆積，結
  果發現Ca, Mg, Mn, Zn等雜質一直在堆積。a
• 英文摘要： A method of hydrochloric acid and TBPsolvent extraction was used in this experimentto produce aluminum oxide from Yangminshanlow-grade bauxite. The TBP solvent contained90% Tributyl phosphate and 10% kerosene.The experiment included the oxidation of ferrousion in the bauxite by calcination, leaching ofthe calcined bauxite by hydrochloric acid, re-moval of the ferric ion from the leaching so-lution, condensation, and crystallization of alu-minum chloride from the purified leaching so-lution, and thermal decomposition of the crystalto obtain aluminum oxide. During thermaldecomposition of aluminum chloride a by-product hydrochloric acid was recovered forreuse. The TBP solvent after solvent extractionwas washed with clean water for reuse. During the calcination it was necessary tosupply enough air for oxidizing the bauxite. Inorder to oxidize the ferrous ion completely, thebest calcination temperature was 500℃-700℃.The extractability of aluminum oxide from thebauxite decreased only slightly when it wascalcined within this temperature range. Whenthe stoicheiometrical amount of 20% hydrochloricacid was used for leaching, 95% of aluminumoxide and 90% of ferric oxide were extractedfrom the bauxite. When 50% of the stoichei-ometric amount of hydrochloric acid was usedin leaching, both the extractability of aluminumoxide and ferric oxide decreased but the latterwas even much lower. The ferric chloride extraction capability ofTBP solvent depended on the acidity of theleaching solution, the concentration of ferric andaluminum ions. The higher the concentrationof ferric ion, aluminum ion, and chloride ionwas, the higher the distribution coefficient ofthe ferric ion was during solvent extraction.Under suitable operation condition, it was possi-ble to remove all the ferric ion from the le-aching solution so that the purity of aluminumoxide obtained subsequently could meet thespecification of aluminum industry. During theregeneration of the solvent for reuse, it wasfound that six times the volume of the solventof water was enough to clean the solvent.During repeated use of the hydrochloric acidit was found that the impurities such as Ca,Mg, Mn, and Zn were gradually built up inthe hydrochloric acid.
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