高铁三水铝石矿拜耳法溶出过程中铝针铁矿的行为

李小斌^{1, 2}，孔莲莲^{1, 2}，齐天贵^{1, 2}，周秋生^{1, 2}，彭志宏^{1, 2}，刘桂华^{1, 2}

(1. 中南大学 冶金科学与工程学院，长沙410083；
2. 中南大学 难冶有色金属资源高效利用国家工程实验室，长沙 410083)

摘 要：为了查明铝针铁矿含量高的红土型铝土矿拜耳法溶出过程中氧化铝溶出率低的原因，研究针铁矿在溶出过程中的转化规律及其对氧化铝溶出率的影响。结果表明：在溶出温度为110~240 ℃时，该类型铝土矿中的铝针铁矿基本不发生转化，其中的氧化铝难以溶出；提高溶出温度到260 ℃或在240 ℃左右溶出时，添加干矿石量3%的石灰可促使铝针铁矿转化为赤铁矿，且氧化铝的溶出率随着针铁矿转化程度的增加而提高。加入非钙质添加剂也可以促使铝针铁矿在溶出过程发生结构转变，且氧化铝几乎完全参与反应，从而说明此类铝土矿中铝针铁矿在溶出过程中难以转变是红土型铝土矿中氧化铝溶出率低的重要原因。

关键词：三水铝石矿；高铁；溶出；铝针铁矿

Effect of alumogoethite in Bayer digestion process of high-iron gibbsitic bauxite

LI Xiao-bin^{1, 2}, KONG Lian-lian^{1, 2}, QI Tian-gui^{1, 2}, ZHOU Qiu-sheng^{1, 2}, PENG Zhi-hong^{1, 2}, LIU Gui-hua^{1, 2}

(1. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;
2. National Engineering Laboratory for Efficient Utilization of Refractory Non-ferrous Metals)

Abstract:The transformation law of goethite and its effect on the alumina recovery were investigated in order to determine the reason of low alumina recovery in Bayer digestion process of gibbsitic bauxite with high alumogoethite content. The results show that the goethite present in this kind of bauxite has no obvious change in the digestion temperature range of 110 ℃ to 240 ℃ with low alumina recovery. And alumogoethite can be transformed to hematite by increasing digestion temperature to 260 ℃ or adding lime of 3% of dry ores added at about 240 ℃, and the alumina digestion rate increases with the increase of the goethite conversion degree. Adding non-calcareous additives in the re-digestion process of red mud containing goethite can promote the structure transformation of alumogoethite and thus alumina almost reacts completely. The transition of alumogoethite into other forms in Bayer digestion process is important for alumina recovery for lateritic bauxite.

Key words:gibbsitic bauxite; high-iron; digestion; alumogoethite