(中南大學 資源加工與生物工程學院，長沙 410083)
摘 要: 提出熱活化脫硅技術處理某煤系硫鐵礦浮選尾礦制備鋁精礦，對制備氧化鋁精礦的工藝制度及脫硅機理進行研究。結果表明：該尾礦適宜的熱化學活化脫硅制度為活化焙燒溫度1 150 ℃、焙燒時間15~20 min、堿浸溶硅溫度125~140 ℃、溶出時間30 min、NaOH濃度140 g/L。在此條件下，對Al2O3和SiO2含量分別為46.22%和28.33%(質(zhì)量分數(shù))的硫鐵礦浮選尾礦，焙砂SiO2溶出率達到71.91%，所得鋁精礦中Al2O3含量達69.29%，鋁硅比5.59。XRD結果表明：硫鐵礦尾礦中伊利-蒙脫石、高嶺石和葉臘石等鋁硅酸礦物在焙燒過程中活化分解生成無定形SiO2和少量莫來石，與此同時，一水硬鋁石轉變成α-Al2O3。在焙砂的堿浸過程中，無定形SiO2溶解于NaOH溶液被脫除，而α-Al2O3和莫來石不能溶解，同時生成的水合鋁硅酸鈉(Na8Al6Si6O24(OH)2(H2O)2)將導致SiO2溶出率降低。焙燒過程中尾礦中的黃鐵礦轉化為赤鐵礦、銳鈦礦部分轉化成金紅石，在堿浸過程中它們均不會溶解而進入鋁精礦中。
關鍵字: 硫鐵礦；鋁精礦；尾礦；熱化學活化；脫硅
（School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract:Aiming at preparing alumina concentrate from coal-derived pyrite flotation tailing, a desilication technique using thermochemical activation process followed by alkali leaching was proposed, and the suitable processing parameters and desilication mechanism were investigated. The results show that the optimal thermochemical activation processing parameters are as follows: roasting temperature 1 150 ℃, roasting time 15-20 min, alkali leaching temperature 125-140 ℃, leaching time 30 min and NaOH concentration 140 g/L. In this case, an alumina concentrate with 69.29%Al2O3 and mass ratio of alumina to silica (A/S) of 5.59 is obtained from a pyrite flotation tailing bearing 46.22%Al2O3 and 28.33%SiO2 (mass fraction), and the corresponding desilication ratio is 71.91%. XRD results show that aluminosilicates of the pyrite flotation tailing, including illite-montmorillonite, kaolinite and pyrophyllite, are decomposed into amorphous SiO2 and small amount of mullite after thermochemical activation. Meanwhile, diaspore is transformed into α-Al2O3. During the alkali leaching of activated materials, amorphous SiO2 dissolves in the caustic soda, while mullite and α-Al2O3 do not dissolve, and the formation of sodium aluminosilicate hydrate (Na8Al6Si6O24(OH)2(H2O)2) during leaching leads to a decrease of desilication. Otherwise, rutile from thermal transformation of portion anatase, as well as hematite from oxidation, is not capable of being dissolved in alkali solution and shifted to alumina concentrate.
Key words: pyrite; alumina concentrate; tailing; thermochemical activation; desilication
