拜耳法高压溶出液中铁浓度变化规律的研究

模拟拜耳法溶出一水硬铝石过程, 基于铝酸钠溶液中铁浓度的变化规律, 研究了S^2-、Na₂O_k、Na₂CO₃、Na₂SO₄浓度变化对Fe(OH)₃、FeS、FeS₂反应行为的影响规律。实验结果表明: 在260 ℃、反应时间60 min、Na₂O_k 160～300 g/L时, 随着体系中硫化钠浓度的升高, 加入氢氧化铁时铁浓度明显升高, 而加入FeS和黄铁矿时溶液中铁浓度略有降低, 这可能与多硫化铁和羟基硫代铁酸钠的生成条件有关; 随着苛性碱浓度的升高, 加入氢氧化铁时, 溶液中铁浓度变化不明显, 而加FeS时溶液铁浓度降低, 加黄铁矿溶液铁浓度却升高; Na₂CO₃对溶出液中铁浓度有明显的促进作用; 而Na2SO4对溶出液中的铁浓度的影响不明显。

Study on Variation Rule of Iron in the Aluminate Solution after Digestion Process at High Temperature by Bayer Process

The influence of concentration  variations of  S^2-、Na₂O_k、Na₂CO₃、Na₂SO₄ on the reaction behavior of  Fe(OH)₃, FeS and FeS₂ was studied on the basis of the variation rule of iron concentration in aluminate solution. The results showed that under the conditions of  260 ℃ temperature, reaction time of  60 min and  Na2Ok 160～300 g/L, the increase of S^2- ion concentration could favor iron into aluminate solution with  addition of  Fe(OH)₃, while the iron concentration decreased with  addition of FeS or pyrite. The possible explanation was the formation of FeS_x and Na₂[FeS₂(OH)₂] during digestion process. The increase of Na₂O_k concentration could promote iron concentration in aluminate solution with  addition of pyrite, but had little  effect on  iron concentration with addition of  Fe(OH)₃ and favor the precipitation of iron with  addition of FeS. The results also showed that addition of Na₂CO₃ can obviously promote iron concentration in aluminate solution, and Na₂SO₄ had little effects on iron concentration in the aluminate solution.