Desilication and recycling of alkali-silicate solution seeded with red mud for low-grade bauxite utilization
Desilication and recycling of alkali-silicate solution seeded with red mud for low-grade bauxite utilization
复制标题
低品位铝土矿利用赤泥碱硅酸盐溶液的脱硅与回收
DOI：
10.1016/j.jmrt.2020.04.095
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Li Junqi
中科院分区：
文献类型：
--
作者：
Xu Yingpeng;Chen Chaoyi;Lan Yuanpei;Wang Linzhu;Li Junqi
低品位高硅铝土矿碱浸脱硅时，会产生大量的碱硅酸盐溶液。为了实现碱硅酸盐溶液的循环利用，需要对碱硅酸盐溶液进行脱硅处理。比较了赤泥和赤泥与CaO的混合物作为碱硅酸盐溶液脱硅剂的效果，并分析了其脱硅机理。结果表明，当赤泥加入量为30-50 g/L时，脱硅率仅为36-38%，而加入量为30 g/L、钙硅比为1的CaO混合物时，脱硅率可达89%以上。通过SEM-EDS等手段分析表明，这主要是由于方钠石晶种在赤泥中的生长及其与CaO的协同脱硅作用。铝土矿经历循环脱硅，氧化铝/二氧化硅比从1.44.1增加到>7.5。有效利用了赤泥和碱硅酸盐溶液，大大降低了脱硅工艺的成本，从而使其适用于拜耳法中的低品位铝土矿。
When low-grade high-silica bauxite undergoes desilication by alkaline leaching, a large amount of alkali-silicate solution will be produced. To realize its recycling, the alkali-silicate solution needs to be desiliconized. In this study, the effectiveness of red mud and a mixture of red mud and CaO as desilication reagents of the alkali-silicate solution are compared and the desilication mechanisms were analyzed. Results show that when adding 30–50 g/L of red mud, the desilication rate is only 36–38% while adding 30 g/L of red mud and CaO mixture with a calcium-silicon ratio of 1 reaches a desilication rate of ∼89%. Analyses by SEM-EDS and other mean show that this is mainly due to the growth of sodalite seed crystals in red mud and its synergistic desilication with CaO. Bauxite underwent cyclic desilication and the alumina/silica ratio was increased from ∼4.1 to >7.5. Effective utilization of red mud and alkali-silicate solution greatly reduces the cost of the desilication process, thereby making it applicable to low-grade bauxite in the Bayer process.