短流程低耗高效综合利用高铁铝土矿中铁的基础研究

High iron diasporic bauxite resource is rich in China,however, till date ,there is no economic method for efficient and comprehensive utilization of iron present in this kind of bauxite at home and abroad,resulting in large amounts of red mud and difficulties in ultimately comprehensive utilization of red mud and exploitation of high iron diasporic bauxite with low mass alumina to silica ratio.Being very different from previous studies of recovering iron either from the raw bauxite directly or from the red mud passively, and based on our recent discovery that hematite could be reduced to magnetite by adding organic reductant in the high pressure digestion process of diasporic bauxite,we propose creatively that hydrothermal reduction of iron-bearing minerals and mineralogical reconstruction of red mud are both achieved simultaneously together with the satisfying digestion effect of aluminium bearing minerals in the same process of bauxite high-pressure digestion,so that relatively separate magnetite with even and appropriate particle size is obtained to realize the efficient iron recovery from red mud by magnetic separation.Focused on the key scientific problem of particle crystallization behavior and its control during the phase formation and conversion process under the high pressure digestion conditions, the interaction characteristics among the aluminate solution,interface,reductant and reduction product and the behavior of mineral dissociation,aggregation and growth are to be investigated thoroughly,in order to reveal the mechanisms of hydrothermal reduction of iron-containing minerals and the mineralogical reconstruction of red mud, and thus to provide the controlling principle and methods.And finally the technological prototype for low-consumption high-efficient comprehensive utilization of iron present in high iron diasporic bauxite is proposed with iron recovery of greater than 90% and iron grade of magnetic concentrate of more than 62%.

我国高铁一水硬铝石矿储量丰富，但迄今国内外尚无法经济综合利用其中的铁，导致赤泥量大、综合利用难，且大量高铁低铝硅比矿石不能利用。区别于已有从原矿或被动地从赤泥中回收铁的研究，本项目基于拜耳法高压溶出条件下添加有机物可使赤铁矿还原成磁铁矿的新发现，创造性提出在一水硬铝石矿高压溶出过程中，同步完成矿石中铁矿物水热还原和赤泥矿相定向重构，获得与赤泥其他组成矿物解离、单体粒度均匀适中的磁铁矿，从而通过赤泥磁选经济实现铝土矿中铁的综合利用。项目拟围绕高压溶出条件下物相形成与转化过程的颗粒结晶行为与调控这一关键科学问题，从宏观和微观层面深入研究溶液、界面、还原剂、产物间的相互作用规律和还原固相产物解离、聚集与长大行为，揭示铝土矿高压溶出过程中铁矿物水热还原机理和赤泥矿相重构机制，并提出其调控原理和方法，开发短流程低耗高效综合利用高铁一水硬铝石矿中铁的技术原型，达到铁回收率>90%，铁精矿品位>62%。

我国高铁一水硬铝石矿储量丰富，由于无法经济高效利用其中的铁，导致赤泥产出量大、综合利用难，且大量高铁低铝硅比矿石不能利用。本项目提出了拜耳法还原溶出工艺，在溶出条件下添加有机物，在溶出氧化铝的同时，同步完成矿石中铁矿物水热还原和赤泥矿相定向重构，获得与赤泥其他组成矿物解离、单体粒度均匀适中的磁铁矿，从而通过赤泥磁选经济实现铝土矿中铁的综合利用。项目围绕高压溶出条件下物相形成与转化过程的颗粒结晶行为与调控这一关键科学问题，从宏观和微观层面深入研究了溶液、界面、还原剂、产物间的相互作用规律和还原固相产物解离、聚集与长大行为，以及铝土矿高压溶出过程中铁矿物水热还原机理和赤泥矿相重构机制，项目研究取得的主要成果有： .1）研究了铁矿物与铝酸钠溶液反应的热力学和动力学，并阐明了铝酸钠溶液组成及其结构、杂质离子以及有机物对铁矿物反应行为的影响规律。.2）明确了还原剂在铝酸钠溶液中的反应行为，并对固液界面层溶液离子结构及其演变进行了分析，发现了中间产物α-Fe(1-x)AlxOOH和转化产物Fe3O4的形成规律，揭示了表面磁化调控矿物粒度的机理；研究了铁硅矿物的表面特性，改变了现行赤泥的赋存状态，提出了赤泥矿相定向重构调控方法；明确了钛/铁矿物的反应行为与平衡固相分配机制，提出了消除钛酸钠阻滞作用机理。.3）开发了短流程低耗高效综合利用高铁一水硬铝石矿中铁的技术原型。通过在还原溶出过程加入矿石质量1%的还原剂铁粉，可使氧化铝相对溶出率达99%；通过调控还原剂表面特性、颗粒级配以及溶出液结构，同步实现赤铁矿的转化和解离，还原溶出赤泥采用弱磁性分选后所得铁精矿全铁（TFe）品位>58%，铁回收率>90%，外排赤泥减排>75%。.研究成果将为我国高铁一水硬铝石矿中铁的短流程、低耗高效综合利用提供坚实的理论和技术支撑，预期产业化应用前景广阔，经济社会效益显著。目前正与多家氧化铝企业洽谈合作，共同推进项目的产业化。