预脱硅及石灰配比对铝土矿溶出性能的影响

Effect of Pre-desilication and Lime Ratio on Dissolution Performance of Bauxites

针对在氧化铝溶出生产过程经常出现溶出效果和脱钠效果突然恶化的情况,对遵义地区几个主要矿点的铝土矿开展溶出试验。在参照生产上常规石灰配入量,溶出温度265℃、溶出时间60 min、分子配比1.4的条件下,铝土矿1和2未经预脱硅处理得到的溶出效果和脱钠效果都非常差,大幅增加石灰配入量或通过14 h预脱硅处理后情况可以得到明显改善,原因是长时间预脱硅提高了碱液对铝土矿细小缝隙的浸润以及铝土矿与石灰的接触程度,还消除了部分石灰活性不足的问题,起到了与增加石灰添加量一样的作用,消除了铝土矿中钛杂质对溶出性能的严重影响。建议工厂在设计、生产中增加或强化预脱硅生产工序,可以有效解决混入的难溶铝土矿问题,减少生产中苛性碱、铝土矿和石灰的消耗损失。

To address sudden deterioration of dissolution effect and sodium removal effect during alumina dissolution,experimental study on dissolution verification of bauxite from several main ore sites in Zunyi area was carried out.Under the conditions of conventional lime dosage of production,dissolution temperature of 265℃,dissolution time of 60 min and molecular ratio of 1.4,it is found that dissolution effect and sodium removal effect of predesilication bauxite No.1 and No.2 are very poor,but the situation can be significantly improved by greatly increasing lime dosage or by predesilication treatment for 14 h.The reason is that long time predesilication improves infiltration of alkali liquor into fine cracks of bauxite and contact extent between bauxite and lime,and also eliminates insufficient lime activity,which plays the same role as increasing lime dosage,and eliminates big influence of titanium impurities in bauxite on dissolution performance.It is suggested that predesilication process be added or strengthened during design and production of plant,which can effectively solve problem of mixed indissolvable bauxite and reduce consumption loss of caustic soda,bauxite and lime in production.