湿法炼锌溶液中硫酸亚铁的高温氧化水解沉淀行为及机理研究

Separation of zinc and iron is a key technology in hydrometallurgical zinc process. The hematite precipitation process for removing iron is an effective way to realize high efficient separation of zinc and iron, has a broad application prospect. This project for crystallization of ferrous sulphate and back dissolve of produced hematite in hematite precipitation separation of zinc and iron process, with the oxydrolysis and hydrolysis process of ferrous sulphate as the breakthrough point. Study the ferrous sulfate crystal phase structure, dissolve features and transformation rules, and the ferrous sulfate gas-solid-liquid phase oxidation-hydrolysis reaction mechanism. Establishment the kinetics model and coupling principle during the process of the crystallization, dissolve, oxidation and precipitation of ferrous sulfate. And obtain the fine grain growth of hematite and the precipitation behavior. Make sure the thermodynamic stability of hematite area, through the calculation and drawing of iron - sulfur - water ternary system thermodynamic state diagram. By using modern detection methods, studies the influence rules of solution composition and precipitation conditions on the hematite chemical composition, phase composition, crystal form, particle size and size distribution of ferric oxide, and diffusion rules of gas - solid - liquid phase. Reveal the rule of fine grain nucleation, growth, reunion and grew up and characteristics of ore phase transition in hematite precipitation process, and the mechanism of back dissolve of hematite. The purpose is to suppress the back dissolve of hematite and improve the effect of zinc and iron separation. The implementation of the project is performed to break through the difficult problems in industrial applications，master the basic theoretical problems and kernel technology of the hematite process and provide an academic supports to realize industry application at a large scale.

锌铁分离是湿法炼锌过程的关键技术，赤铁矿法沉铁技术是实现锌铁清洁高效分离的有效途径。本项目针对赤铁矿法分离锌铁过程中硫酸亚铁的结晶和新生赤铁矿的返溶等关键问题，以硫酸亚铁高温氧化沉淀行为为突破口，重点研究硫酸亚铁晶相结构、溶解特性和转化规律以及硫酸亚铁气-固-液相氧化-水解反应机理，建立硫酸亚铁的结晶-溶解-氧化-沉淀行为耦合原理与动力学模型，明确赤铁矿微细晶粒长大及沉淀行为。计算和绘制铁-硫-水三元系热力学状态图，明确赤铁矿法沉铁的热力学优势区；研究溶液成分和沉铁条件对赤铁矿渣化学成分、物相组成、结晶形态、氧化铁颗粒大小、颗粒分布的影响规律及其气-固-液相的扩散规律，揭示赤铁矿法沉铁过程微细晶粒成核、发育、团聚和长大规律、矿相转变特征及返溶机理，从而抑制新生矿相返溶，提高锌铁分离效果，解决和掌握赤铁矿法沉铁过程的核心技术，突破工业应用中的难题，丰富其基础理论，为其推广应用提供理论支撑。

针对湿法炼锌工艺过程赤铁矿法分离锌铁的技术，研究了硫酸亚铁的高温结晶-溶解-氧化沉淀行为。绘制了铁-硫-水三元系热力学状态图，明确了赤铁矿法沉铁的热力学优势区，研究了硫酸亚铁结晶、溶解特性和氧化水解反应机理，建立了硫酸亚铁的结晶-溶解-氧化-沉淀行为耦合原理与动力学模型，明确了赤铁矿微细晶粒长大及沉淀行为。研究了溶液成分和沉铁条件对赤铁矿渣化学成分、物相组成、结晶形态、氧化铁颗粒大小、颗粒分布的影响规律，揭示了赤铁矿法沉铁过程微细晶粒成核、发育、团聚和长大规律、矿相转变特征及返溶机理。. 通过研究获得的主要结论如下：.（1）硫酸亚铁在高温溶液中的溶解度明显降低，赤铁矿的析出首先要经历了硫酸亚铁的结晶、再溶解。硫酸亚铁的溶解是决定整个反应速率的限速步骤。但反应速率较慢，有利于维持较低的过饱和环境，有利于生产优质赤铁矿。.（2）硫酸亚铁高温氧化水解沉淀赤铁矿的过程包括两个步骤：亚铁离子氧化为三价铁离子和三价铁离子的水解。亚铁离子的氧化反应近似符合二级反应速率，硫酸锌能促进亚铁离子的氧化。.（3）赤铁矿法除铁工艺为可控操作，溶液中钾与钠离子的存在会导致铁矾生成，降低赤铁矿渣含铁量，过高硫酸锌浓度不利于赤铁矿法沉铁，较低温度下添加返渣作为晶种可析出高品质的赤铁矿。.（4）随着反应进行，体系中酸浓度增加，不同杂质的热力学稳定性不同。亚稳相向赤铁矿的转化由易到难的顺序为：FeOOH > NaFe3(SO4)2(OH)6) > KFe3(SO4)2(OH)6,生成的铁矾类物相需要较长的反应时间或较高的温度来溶解和转化，以保证析出较纯的赤铁矿。.（5）赤铁矿沉淀产物中不同大小的球形颗粒高度聚集，并检测纺锤形，相对较小的颗粒表明了反应过程的主要特征是均匀的成核和微晶的聚集增长。. 本项目发表论文11篇，授权专利2项，获得科技奖励1项，毕业硕士2名，在读博士生2名、硕士生3名。