生物质高压水热还原法分离高铁铝土矿中铁的应用基础研究

When the high iron bauxites are treated with Bayer process, the oxide irons are transformed to hematite and it is hard to separate the hematite from red mud by magnetic separation. The utilization of iron mineral and the enrichment of rare metal are difficult. The current ways to separation of Al and Fe possesses many problems, such as high energy consumption, process complexity and serious environmental pollution etc. This project proposes a novel research method that is to complete the processes of alumina digestion and oxide iron reduction synchronously. The biomass is utilized as reducing agent to produce high-pressure hydrothermal system with high reduction property and the iron oxides are reduced into magnetite with high degree of liberation in the system. The iron particles easily to be magnetically separated can be obtained and the rare metals elements can be enriched. The new method breaks through the traditional methods to complete the process of alumina digestion and oxide iron reduction in the hydrothermal environment, and that can separate the Al and Fe with high-efficiency, low consumption and no pollution. This project research on the scientific problems of the hydrothermal reduction of high iron bauxite by using biomass as reducing agent, which mainly includes The formation rules of hydrothermal system with high reduction property ,the reduction behaviors of iron minerals and the grain growth and cleavage characteristics of metallic phase in supercritical hydrothermal reduction process. The controlling principle and method are provided，and the technological prototype of oxide iron reduction by using biomass as reducing agent is modeled. The successful implementation of this project can realized the comprehensive utilization on high iron bauxite resources.

拜耳法处理高铁铝土矿，铁氧化物转化为赤铁矿进入到赤泥中，难以磁选分离，不利于铁的综合利用及稀有金属元素的有效富集。现有高铁铝土矿铝铁分离方法存在着能耗高、流程复杂及环境污染等问题。本项目提出同步完成铝矿物溶出和铁矿物磁化还原的新方法。即在拜耳法高压溶出过程中加入生物质，生物质可分解并形成强还原性高压水热介质将铁氧化物转化为解离度高的磁铁矿颗粒，为后续磁选分离铁矿物创造有利条件。该方法突破了铝矿物溶出、铁矿物还原分步进行的传统思路，并将铁氧化物的生物质还原局限于水热体系中。本课题围绕新方法，探索生物质水热还原铁氧化物过程的若干科学问题，包括生物质在高压水热介质中的转化规律、铁氧化物在还原性高压水热介质中物相转化机制及磁铁矿颗粒形核、生长、解离规律，通过过程调控与优化，建立生物质高压水热还原法分离高铁铝土矿中铁的技术原型，为低成本、低能耗和高效率实现高铁铝土矿的综合利用提供全新的思路。

拜耳法处理高铁铝土矿，铁氧化物转化为赤铁矿进入到赤泥中，难以磁选分离，不利于铁的综合利用及稀有金属元素的有效富集。现有高铁铝土矿铝铁分离方法存在着能耗高、流程复杂及环境污染等问题。本项目提出同步完成铝矿物溶出和铁矿物磁化还原的新方法。即在拜耳法高压溶出过程中加入生物质，生物质可分解并形成强还原性高压水热介质将铁氧化物转化为解离度高的磁铁矿颗粒，为后续磁选分离铁矿物创造有利条件。该方法突破了铝矿物溶出、铁矿物还原分步进行的传统思路，并将铁氧化物的生物质还原局限于水热体系中。本课题围绕新方法，探索生物质水热还原铁氧化物过程的若干科学问题，包括生物质在高压水热介质中的转.化规律、铁氧化物在还原性高压水热介质中物相转化机制及磁铁矿颗粒形核、生长、解离规律，通过过程调控与优化，建立生物质高压水热还原法分离高铁铝土矿中铁的技术原型，为低成本、低能耗和高效率实现高铁铝土矿的综合利用提供全新的思路。研究发现以循环母液 （αk为 3.12，Nk为 210.27 g/L）为溶出体系 ，当温度为 240 °C，还原时间为 40 min，淀粉用量与干矿比值为 1:10，赤铁矿最高还原率为 97.5%,一水硬铝石最高溶出率约为 98.0%。在碱性还原体系下， Fe2O3向 Fe3O4的定向转化分三步进行 Fe2O3首 先溶于碱性水液中形成 FeO2-，淀粉在碱性水热条件下通过降解，形成强还原体系，将 FeO2-还原成 Fe2+，Fe2+在碱液中进一步反应生成 在碱液中进一步反应生成 Fe(FeO2)2。