高铁铝土矿同步转化与异步分离回收工艺基础研究

High grade bauxite become more and more scarce these days. The development of refractory buaxite as alternative resource is becoming a great concern for both engineers and researchers. In ferric bauxite ore, minerals that bear iron and aluminum can reach 80% of its total. Considering this, ferric bauxite is a kind of rich ore with remarkable potential value to some extent. Some utilization scheme has been presented to treat such resources at home and abroad. However, due to its poor natural endowments, ferric bauxite hasn't been commercialized yet. Soda-lime method is a common processing technology of bauxite, and direct- reduction technology has also been reported to be used in treating oolitic hematite sussfully. If we could combine the two techniques, which would make the reduction process of hematite to iron and the sintering process of bauxite to Sodium aluminate occur simultaneously in reducing atmosphere, the comprehensive utilization of ferric bauxite might be solved satisfactorily. Our echelon presented a heat insulation scheme in reduction-atmosphere to treat ferric bauxite. But some disadvantages of the scheme appeared, such as high dosage of soda-lime and high consumption of alkali. Preliminary analysis shows that they caused by the high content of iron in ore and the reducing atmosphere in insulation process. This task mainly focuses on the effect of reducing atmosphere on bauxite sintering reactions, and interactions between soda-lime and target minerals. The objective is to explore the affecting factors and mechanism of mass transfer and alkali consumption in sintering process, and provide a theoretical support for the commercialized utilization of ferric bauxite.

近年来，优质资源日趋短缺，开发难选冶铝土矿作为替代资源已成广大学者的共识。高铁铝土矿中铝、铁矿物的含量和可达80%以上，从可利用矿物的总量上来说是一种富矿，潜在的利用价值显著。国内外先后提出了多种处理方案，但因矿石禀赋差，至今未能实现高铁铝土矿的规模化应用。碱石灰烧结法是常见的铝土矿处理工艺，直接还原法也在处理鲕状赤铁矿等难选冶矿物中有成功报道。若将二者结合，在还原气氛中同步实现含铝矿物的烧结和含铁矿物的还原，则可能解决高铁铝土矿的综合利用难题。本课题组提出了在还原气氛中保温处理高铁铝土矿的方法，但前期研究发现该法存在碱石灰用量大、碱耗高的问题。初步分析诱因是原矿中较高的含铁量和保温过程中的强还原气氛。本课题拟以还原性气氛对含铝矿物烧结反应的影响，和碱石灰与目标矿物之间的相互作用为研究重点，探索烧结过程中传质和碱耗的影响因素和机理，为高铁铝土矿的商业化应用提供理论支撑。

近年来，优质资源日趋短缺，开发难选冶铝土矿作为替代资源已成广大学者的共识。高铁铝土矿中铝、铁矿物的含量和可达80%以上，从可利用矿物的总量上来说是一种富矿，潜在的利用价值显著。国内外先后提出了多种处理方案，但因矿石禀赋差，至今未能实现高铁铝土矿的规模化应用。. 本课题组提出了一种在还原气氛中同步实现含铝矿物的烧结和含铁矿物的还原的方法。课题从还原性气氛对含铝矿物烧结反应的影响，和碱石灰与目标矿物之间的相互作用为研究重点，探索烧结过程中传质和碱耗的影响因素和机理。研究发现，含铁矿物的还原反应和含铝矿物的烧结过程可以同步进行，但反应体系中大量溢出的还原性气体会加快碱石灰消耗。且含铁矿物还原和含铝矿物烧结之间存在约300℃的温度差，在这期间有部分含铁矿物发生烧结反应。即，纯碱在与含铝矿物作用之前，首先与赤铁矿发生作用生成铁酸钠。后者在温度升高后容易在还原气氛中被还原，游离的Na2O扩散到气相，随还原性气流溢出反应系统，从而增加工艺的碱耗。.课题还系统研究了通过构造人工矿物集合体的方式提高原料利用效率的方法和机理。发现人工集合体的构造方式对氧化铝、硅、钠的浸出效果有影响。混合后磨矿可以促使反应物之间形成某种程度的“定向包覆”，能够获得较高氧化铝、钠溶出率和较低的硅溶出率。. 研究中还发现高铁铝土矿直接还原熟料（下称：熟料）中的铁含量高、铝含量低。若将熟料磨细后直接溶出就需要在溶出系统中大量输送无效铁颗粒。且前期研究发现，这些铁颗粒在循环过程中还会以离子形式污染氧化铝溶出液。先磁选后溶出虽然能预先分离出铁颗粒，但磁选冲洗水又会稀释氧化铝溶出液。研究还发现熟料含铁量是影响溶出液中铁离子浓度的主要因素，根据重力分选原理利用脉动浓缩管分离出料浆中的铁颗粒可以降低后者对溶出液铁离子含量的影响。溶出液硅量指数随料浆液固比的升高而降低，但降低幅度逐渐较小，对氧化铝溶出液质量的影响可逐渐降低。