降低拜耳法溶出液苛性比值的研究

【作者】 何英；

【导师】 任凤莲；

【作者基本信息】 中南大学 ， 应用化学， 2007， 硕士

【摘要】 本文的研究目的:一是以高品位铝土矿为原料,在现行生产条件和控制铝土矿相对溶出率不低于93%的前提下,通过改变原矿浆配比和优化溶出条件,使溶出液苛性比值ak降低到1.42～1.44,揭示原矿浆配料等生产工艺指标对拜耳溶出过程的影响规律,为生产减少能耗提高产量提供依据;二是对中低品位铝土矿拜耳溶出工艺进行研究,探寻适宜的工艺条件,为提高中低品位铝土矿的溶出率提供理论依据;三是对常用絮凝剂进行对比实验,确定各絮凝剂的沉降效果,为生产优选出经济、好用的絮凝剂。研究方法:为了使实验具有较好的模拟性,用高压釜模拟生产现场,预脱硅实验用2000毫升的锥形瓶在100℃的恒温水浴中进行。赤泥沉降性能实验用高300毫升、体积250毫升的沉降管在100℃的恒温水浴中进行。整个过程与生产现场具有很好的一致性。结论:对A/S在10左右的中高品位铝土矿,采用石灰添加量8%～14%(干矿石量),母液浓度N_K230～250g/L,母液ak＞3,磨矿粒度98μm～300μm,配料分子比1.42的配矿条件,在溶出温度不低于255℃,溶出时间不低于45分钟的溶出条件下,可得到相对溶出率不低于93%,溶出液ak降低到1.40～1.43的最佳溶出效果。原矿浆经6小时的预脱硅有利于溶出指标的进一步优化。对中低品位铝土矿,宜采用石灰添加量20%～25%、较高的溶出温度和尽可能长的溶出时间以提高溶出率和降低碱耗、预脱硅有利于溶出。对于几种常用絮凝剂的使用情况作了对比研究。结果表明:英国产Alcar663优于国产A-1000絮凝剂,其用量为干赤泥量的0.05%～0.06%时,沉降效果达到最好。应用:本课题从生产实际出发,根据导致拜耳法种分原液苛性比值偏高的原因,对降低苛性比值的途径进行探讨,采取改进措施优化高压溶出的溶出条件,降低分解原液苛性比值,提高了溶出率。通过增加石灰添加量降低了中低品位铝土矿的碱耗,有效地降低了氧化铝的生产成本,可以生产出符合现代铝电解工业要求的砂状氧化铝。更多还原

【Abstract】 There are three purpose of the investigation.The first,in the existing produce condition of SHANⅪcompany using high grade aluminium mine controlling the comparatively dissolve ratio not under 93% (premises precondition)via changing original mine slurry ratio and optimizing dissolve condition the ak of dissolved liquid will be falled to 1.42～1.44,which will open out the effecting rule of arts and crafts of original mine slurry’s ratio to Baier’s smelting course in order to providing qualification of SHANⅪcompany to rebuild craftwork.The second,to study the arts and crafts of Baier’s smelting course of SHANⅪcompany’s low grade aluminium mine in order to fitting technics condition,which will provide theoretics gist to evening manufacture design.The third,making sure the effect of sedimentation by parallel experimentation on SHANⅪcompany’s flocculants in order to selecting excellent flocculants for producing.Method:in order to making the experimentation have preferable simulation we use high pressure kettle to simulate production scene.The beforehand doffing silicon is done by 2000mL taper flask in the constant temperature water bath.The slag sedimentation capability experiment is done with a pipe which is 300mm high and volume is 250mL in 100℃constant temperature water bath.The course is of good simulation.Some conclusions are educed.If the accession of lime be within 8%～14%,the concentration of originally liquid be 230～250g/l,the ak of originally liquid be exceed 3,the granularity of mine be 98μm～300μm, the ratio of mixing material be 1.42,the temperature of dissolving be exceed 255℃,the time of dissolving exceed 45minute,the comparatively dissolve rate will be exceeded 93%and the ak will be reduced 1.40～1.43 to the high grade aluminium mine.If the original mine slurry be doffed silicon in advance,the dissolve condition will be more optimized.For low grade aluminium mine in order to heighten dissolve rate and debase alkali cost the upper temperature and long time are appropriate in the course of melting mine.更多还原