用煅燒-瀝濾工藝從粉煤灰中提取高純超細氧化鋁
發布時間: 2012-09-15 10:18 查看: 2905次
粉煤灰 氧化鋁 提取 煅燒-瀝濾工藝
摘要：介紹了1種采用煅燒-瀝濾工藝從粉煤灰中提取氧化鋁(Al2O3)的新方法.以碳酸鈉(NaCO3)為活化劑,在900 ℃下煅燒,使粉煤灰中惰性的Al2O3轉變成活性的可以溶出的鋁鹽.選用硫酸(H2SO4)為活性鋁鹽的溶出劑,在一定溫度下溶出鋁鹽,使活化后粉煤灰中的Al2O3以液相形式溶出.用乙二胺四乙酸為絡合劑有效除去鋁鹽[Al2(SO4)3]中的雜質鐵(Fe3+)等,用蒸餾水洗滌除去鈉(Na+)和其它可溶性雜質,有效提高Al2O3粉體的純度.通過添加合適的分散劑、控制氫氧化鋁[Al(OH)3]的結晶、干燥及煅燒的工藝條件,大大提高了Al2O3粉體的細度.通過X射線衍射、透射電子顯微鏡和N2吸附等技術分析獲得的Al2O3粉體的組成與微觀結構.通過以上工藝,獲得Al2O3的提取率超過98%.將干燥后的Al(OH)3粉體在800 ℃下煅燒得到分散性好的纖維狀γ-Al2O3,其純度(質量分數)達99.6%.
Abstract： A new calcining-leaching process was used to extract high purity alumina (Al2O3) powders from fly ash in this study. The fly ash was mixed with soda (Na2CO3) and calcined at 900 ℃ to yield soluble aluminates. Subsequently the calcined ash was leached with sulfuric acid (H2SO4) to produce a solution containing aluminum. The unwanted metal ions including Fe3+ and Na+ were removed by ethylene diamine tetraacetic acid (EDTA) and water washing. Then added the proper dispersant, controlling the crystallization of aluminum trihydroxide precipitation, and the drying and calcining process was carried out, resulting in ultra fine Al2O3 powders with high purity. The characteristics of the Al2O3 powders were examined by means of X-ray diffraction, transmission electron microscope and the Brunauer, Emmet and Teller (BET) surface analysis method. The extraction efficiency of Al2O3 can surpass 98%by optimization of the calcination and lixiviation processes. Well-dispersed fibriform γ-Al2O3 powders were obtained by calcining at 800 ℃ and the purity of the ultra fine Al2O3 powders was more than 99.6%.
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