难处理含锡铁尾矿热化学活化焙烧分离锡铁的基础研究

Tin resources supply shortage has become the bottleneck of restricting the sustainable and healthy development of tin industry in China. Meanwhile, the existing tin, iron-bearing tailings deposited in tailing ponds are more than 500 million tons. The tailings have high potential economic value because the total metallic tin and metallic iron in the tailings exceeds 800,000 and 100 million tons, respectively. The traditional beneficiation and smelting processes, however, cannot meet the requirement of utilizing the tin, iron-bearing tailings economically and efficiently. Hence, it’s significant to develop a new technology for effectively using tin, iron-bearing tailings so as to relief the contradiction between the supply and demand of domestic tin resources. This project will use the tin, iron-bearing tailings, taken from a mining area in Gejiu, Yunnan province, as research object, targeting at the recycling of tin and iron, and put forward a new technical idea to directional control component mineral properties based on solid state reduction-roasting and synergistic activation by chemical additives. The project aims at creating mineralogical conditions for the directional separation of tin and iron components. Integrated using multidisciplinary of principles and methods, including mineral processing, extractive metallurgy and high-temperature phase transformation, etc., this project would focus on investigating the thermodynamics, phase transformation, regulation mechanism and separation methods for tin and iron components during the solid reduction roasting in the presence of additives. Based on which, the theoretical basis and technology prototype of efficient separation and recovery of tin and iron from the tin, iron-bearing tailings is established by the thermodynamic activation method. After completion of the project, a new theory and method for the efficient utilization of tin, iron-bearing tailings can be provided, which is beneficial to upgrade the utilization level for the refractory tin, iron-bearing tailings.

锡矿资源供应短缺问题现已成为制约我国锡工业持续健康发展的瓶颈。与此同时，国内现有超过5亿吨的含锡铁尾矿堆存于尾矿库，其中金属锡超过80万吨，金属铁超过1亿吨，潜在极高经济价值，但传统选矿、冶炼技术都无法达到经济、高效利用此类资源的要求。研究开发高效利用含锡铁尾矿的新技术对缓解国内锡矿供需矛盾意义重大。本项目以云南个旧某矿区含锡铁尾矿为对象，以回收利用锡、铁元素为目标，提出了基于固态还原焙烧与添加剂协同活化定向调控组分矿物性能的技术思想，为锡、铁组分由不可分离到可分离的定向转化创造矿物学条件。综合运用矿物加工、提取冶金、高温相变等学科的原理和方法，重点研究固态还原焙烧和添加剂作用下，尾矿中锡、铁等组分转化的热力学、相变规律、调控机制和分离回收方法，建立含锡铁尾矿热化学活化高效分离和回收锡铁的理论基础和技术原型，为含锡铁尾矿的高效利用提供新理论和新方法，提升难处理含锡铁尾矿的利用水平。

国内含锡铁尾矿资源储量达5亿吨以上，其中金属锡超过80万吨、金属铁超过1亿吨，潜在极高经济价值，但传统选矿、冶炼技术都无法高效、经济利用此类资源。本项目以云南典型含锡铁尾矿为对象，以高效分离回收锡、铁组分为目标，通过研究控制气氛焙烧和添加剂作用下，尾矿中锡、铁等组分转化热力学、相变规律、调控机制和分离回收方法，构建含锡铁尾矿热化学活化焙烧-磁选分离回收锡铁的理论基础和技术原型。主要结论有：.①探明了尾矿中锡铁组分难以高效分离的矿物学原因：部分锡石以小于20μm的粒级包裹或夹杂于铁矿物中，少量锡还以晶格取代形式赋存于磁铁矿中，均不具备物理分离条件；②查明了尾矿中主要组分转化热力学：CO-CO2气氛下，SnO2可与铁、钙、硅氧化物反应分别生成Fe3-xSnxO4、CaSnO4、SnSiO3等，中间物相SnO可促进各反应进行；为实现锡铁组分有效分离，必须严格控制热力学条件抑制锡铁组分反应生成Fe3-xSnxO4，同时铁氧化物稳定在Fe3O4阶段，而锡则转化为有利于铁锡分离的含锡物相；③揭示了CO-CO2气氛下主要含锡组分（锡石和锡铁尖晶石）与钙、硅等氧化物的反应机制：通过控制焙烧气氛、温度、添加剂等，可以调控含锡组分与Ca、Si等氧化物间的化学反应，在CO浓度5-20%、800-850oC条件下，锡石表面易吸附CO产生晶格缺陷促进SnO2与CaO反应生成锡酸钙，而锡铁尖晶石则与CaO反应生成磁铁矿和锡酸钙（该反应受Sn4+扩散控制），同时抑制了铁橄榄石、硅酸亚锡等的生成，为后续锡铁组分高效分离提供了物质基础；④开发出含锡铁尾矿高效分离回收锡铁新技术：当CO浓度5-15%、焙烧温度800-850oC、CaO含量10-15%时，CaO与尾矿中的含锡组分反应生成了非磁性的锡酸钙，而铁氧化物转化为磁铁矿，且焙烧产物中未发现铁酸钙、橄榄石等物质；磁选铁精矿铁的回收率和铁品位分别高于85%和65%，铁精矿中锡含量降至0.1%以下，可作为优质炼铁原料，85%以上的锡富集于非磁性尾矿中。.本项目开发的新技术对原料适应性强，为我国储量丰富的锡铁尾矿资源综合利用提供新途径。