弱磁选-硫化磁化复合焙烧-强磁选处理锡铁矿矿相转化与锡、铁回收机理研究

Tin-bearing iron ores reserve large in China,and the iron grade is generally about 30-55%, tin grade about 0.2-1.2%, which are being well worth reclaimed.But they disseminated complicated with other gangue minerals, causing them difficult to be utilized. Aiming at the recovery of tin and iron form tin-bearing iron ores, a new method of low intensity magnetic separation-sulfuration magnetization recombination roasting-high intensity magnetic separation is proposed in this study.Based on the research of mechchanism of tin mineral phase transformation and dissociation, micromechanism of the magnetite fine mineral phase aggregation growth,the oxygen potential collaborative mechanism in the process of sulphuration-magnetization roasting, and the reaction mechanism of high-sulphur coal sulphuration-magnetization, the technology and theory system of high-sulfur coal sulphuration-magnetization roasting of the tin-bearing iron ores to reclaim tin and iron was constructed, and the research contents mainly included the directional reduction of tin and iron, the optimal coupling of the sulfuration and magnetization roasting process,and the behavior law of sulfur and carbon contented in the high-sulfur coal. Implementation of this project is meaningful for the innovation and development of new technology for the tin-bearing iron ores resource utilization, recombinant of mineral processing and metallurgical technology, and the short process clean use of high-sulfur coal.

我国锡铁矿储量丰富，一般铁品位30%-55%，锡品位0.2%-1.2%，但矿中锡、铁物相嵌布关系复杂，资源化利用难度较大。本项目提出弱磁选-高硫煤硫化磁化复合焙烧-强磁选处理锡铁矿实现其中锡、铁综合回收新思路。研究锡物相矿相转化与离解机理、Fe3O4微细矿相团聚结晶长大微观机制、硫化-磁化焙烧过程中氧势协同机制以及高硫煤的硫化磁化反应机理，构建高硫煤硫化-磁化复合焙烧锡铁矿回收锡、铁资源的工艺及理论体系，内容主要包括锡、铁的定向性还原、硫化磁化两焙烧工艺间的优化耦合以及高硫煤中硫、碳元素的行为规律等。本项目的研究对锡铁矿资源化利用、复杂矿选冶工艺重组和高硫煤短流程清洁利用等技术的创新与发展具有重要的学术价值和实际意义。

锡铁矿中锡、铁资源赋存丰富，进行弱磁选-高硫煤硫化磁化复合焙烧-强磁选处理回收其中锡和铁，对锡铁矿资源化利用和高硫煤短流程清洁利用技术创新与发展具有重要学术价值和实际意义。项目以黄铁矿硫化焙烧和高硫煤硫化磁化复合焙烧富集锡铁矿中锡和铁为研究主线，系统研究了锡铁矿中锡物相矿相转化与离解机理、Fe3O4聚集长大动力学机制和硫化-磁化复合焙烧过程中氧势协同机制，并重点讨论了硫化磁化两焙烧工艺间的优化耦合、高硫煤中硫、碳元素的行为规律和高硫煤硫化脱锡机理等，构建了高硫煤硫化-磁化复合焙烧锡铁矿回收锡、铁资源的工艺及理论体系。主要研究结论有：（1）以黄铁矿（FeS2）为硫化剂无烟煤为还原剂，探明了硫化焙烧过程中锡的硫化挥发机理。焙烧温度高于1173 K 时，锡物相硫化反应程度按SnO、Sn、SnO2递减，促进锡的硫化挥发，焙烧过程中锡硫化反应应以 S2 硫化 SnO 生成SnS为主，硫化焙烧脱锡反应反应速率受扩散环节控制；（3）探明了黄铁矿硫化性和还原性的双重作用特征，单独添加黄铁矿时，结合实验研究建立了锡铁矿硫化-磁化复合焙烧工艺及理论体系。焙烧温度1473.0 K，焙烧时间60 min，黄铁矿添加量5.00 %，锡铁矿粒度0.075mm条件下，锡铁矿中赤铁矿全部转化为磁铁矿，锡含量降至0.07%，达到了高炉冶炼入炉矿石原料Sn含量低于0.08%的要求，黄铁矿添加量超过5.00%，锡铁矿中部分被还原的赤铁矿会被进一步硫化为液相FeS，对锡的挥发起阻碍作用；（4）以N2气氛下高硫煤硫化焙烧锡铁精矿脱锡的热力学反应机理和实验研究为基础，探明了高硫煤中的S、C元素与矿中锡、铁元素之间的耦合行为关系，获得了高硫煤硫化脱锡机理。高硫煤的硫化作用主要由其中黄铁矿硫、有机硫和硫酸盐硫转变生成的SO2实现，硫化效率较高；动力学研究表明随着反应进行，限速环节由化学反应控制向扩散控制转变；氮气气氛下，焙烧温度1473K、保温时间60min、高硫煤添加量0.7和粒度100目条件下，焙烧后铁物相大部分转变为Fe，锡含量可降至0.076%。