铝酸钠溶液中铁的行为及其抑制

【作者】 高君丽；

【导师】 李小斌；

【作者基本信息】 中南大学 ， 有色金属冶金， 2007， 硕士

【摘要】 随着我国氧化铝工业的发展，我国的优质铝土矿资源已显严重不足。因此，使用难处理的非优质铝土矿进行氧化铝生产，就成为我国氧化铝工业发展所迫切需要研究的课题。高硫型一水硬铝石矿是一种大量存在的难处理矿石。生产中运用此矿石，由于硫的存在促进了矿石中的铁进入到铝酸钠溶液中。进入到溶液中的铁随着降温和氢氧化铝一起析出，进入到产品中，严重污染产品。因此对铝土矿溶出过程中铁的行为进行研究，并提出降低铝酸钠溶液中铁浓度的方法，具有十分重要的现实意义。实验研究表明：溶出液中铁浓度随溶出时间的延长而增大：S^2-的存在能显著提高溶出液中铁浓度；苛性碱浓度对高压溶出液中铁浓度有比较显著的影响；Na₂CO₃的加入能明显地提高高压溶出液中铁浓度；而Na₂SO₄浓度则对高压溶出液中铁浓度没有明显的影响。对利用添加剂来降低铝酸钠溶液中铁浓度的方法进行了研究，得出如下结论：高压溶出时，沉淀剂NP和弱还原剂NS_x的加入，能大大降低溶液中的铁浓度，当其单独加入量为5g／L时，溶液中的铁浓度分别下降了71.5％和76.3％；常压处理时，加入固体吸附剂RM，可显著降低溶液中的铁浓度，当处理时间为120分钟时，溶液中的铁浓度减少了60.9％；在沉降分离过程中加入无机物MSO能显著降低溶液中的铁浓度；当其加入量为2g／L时，溶液中的铁浓度降幅达77.3％。更多还原

【Abstract】 Presently in china, bauxite resources are consumedly insufficient with thedevelopment of alumina industry. So research on alumina production using non-highquality bauxite is extraordinarily urgent. Generally mineral containing iron does notaffect the alumina production. But when the diaspore with high content of sulfur wasadopted, iron would be dissolved into the sodium-aluminate solution and precipitatealong with aluminum tri-hydroxide with the temperature decreasing, which badlycontaminates the aluminum tri-hydroxide product. Therefore, studying the behavior ofiron during the digestion process and finding the method to restrain the iron content insodium-aluminate solution are great of practical significance.Results demonstrate that the iron concentration in sodium-aluminate solutionincreases with prolongation of the digestion time and S^2- can markedly improve theiron concentration in sodium-aluminate solution. During the high pressure digestionprocess using different bauxite containing iron, caustic soda concentration has greatinfluence on the iron concentration in sodium-aluminate solution, and Na₂CO₃ canevidently improve the iron concentration in sodium-aluminate solution while Na₂SO₄has no effect.Simultaneously, the effects of different additives on the iron content in sodium-aluminate solution are investigated. The results are as follows:Precipitant NP and weak reductant NS_x can greatly reduce the iron content of liquorin the high-pressure digestion process. The iron content was reduced by 71.5% and76.3% respectively after adding the two precipitant （5g/L） individually. Solidabsorbent RM can remarkably reduce the iron content of liquor in the normal-pressuretreatment process. The iron content was decreased by 60.9% when treatment time is120 min. In the sedimentation process, inorganic substance MSO can distinctly reducethe iron content of liquor. The decreased value of iron content is 77.3% with MSOaddition content of 2 g/L.更多还原