低品位红土镍矿矿相定向调控及软磁铁氧体转化机理研究

Comprehensive utilization of laterite ores for preparation of soft ferrite materials is one of the most important ways of synergetic and high-value utilization of metals. However, how to deeply remove impurity for the oriented adjustment and control of mineral phases in low-grade nickel laterite and transformation into soft spinel ferrites is the key problem and challenge. In addition, the influence mechanism of metal doping and impurity on the phase, structure and morphology of spinel ferrites is not clear, and it is difficult to improve electrical and magnetic properties of as-prepared ferrites. In this project, synthesis of multi-metal co-doped magnetic spinel ferrites using limonite and saprolite laterite ores as raw materials by the solid state reaction method is proposed. Based on the experimental in combination with phase diagram and thermodynamic calculation, the reaction mechanisms during the impurity removal process and ferrite transformation process will be systematically investigated. And the mechanisms of oriented adjustment and control of mineral phases of nickel laterite and transformation from treated laterite ores into magnetic spinel ferrites will be revealed. Then the effect of metal doping and impurity on the mineral phases, morphology, cation distribution between the tetrahedral (A) sites and octahedral (B) sites, and impurity SiO2 distribution during the transformation process will be also studied in detail. Finally, the relationship between chemical compositions, mineral phases, process conditions and the structure, electrical, magnetic properties of as-prepared spinel ferrites will be illustrated. The project would provide theory and technology support for mineral phase reconstruction of multi-metal associated resource to transform into spinel ferrite materials with excellent electrical and magnetic performance.

红土镍矿综合利用制备尖晶石型软磁铁氧体是其多金属协同高值化利用的重要途径之一。然而，如何深度去除红土镍矿中杂质元素，实现矿相定向调控及软磁铁氧体转化是关键难题。同时，由于缺乏红土镍矿中多金属掺杂和杂质对铁氧体物相、结构、微观形貌影响等方面的认识，使合成的铁氧体材料电磁性能难以提高。为此，本项目拟以褐铁矿型和腐泥土型红土镍矿为原料，采用固相烧结法合成多元金属共掺杂软磁铁氧体，在实验结合相图和热力学计算基础上，系统研究红土镍矿提质除杂矿相调控和磁铁氧体转化过程反应机理。探究金属掺杂和杂质对磁铁氧体转化过程成分、物相、微观形貌、金属离子在四面体A位和八面体B位占位及杂质赋存形态的影响规律，揭示其影响机理机制，建立红土镍矿成分、矿相、工艺条件和软磁铁氧体结构、电磁性能之间的内在联系，为多金属共伴生资源矿相重构制备性能优良的软磁铁氧体提供理论和技术支撑。

共伴生红土镍矿综合利用制备尖晶石型软磁铁氧体是其多金属协同高值化利用的重要途径之一。本项目以具有高铁低镁的褐铁矿型和低铁高镁的腐泥土型红土镍矿为研究对象，在系统研究乐矿中元素分布赋存规律的基础上，提出了杂质去除预处理和有价金属元素靶向浸出的元素定向富集调控方法，通过调控不同类型红土镍矿的质量比直接进行矿相转化合成了尖晶石型软磁铁氧体，进一步系统研究了矿中金属元素Al/Cr、Co/Mn、Zn以及杂质SiO2等对红土镍矿基软磁铁氧体微观结构和电磁性能的影响规律，阐明了低品位红土镍矿成分、矿相调控机制以及软磁铁氧体转化机理。主要结论有：预处理矿比和煅烧温度是影响软磁铁氧体转化的重要因素，采用碱熔-水浸预处理红土镍矿，当两种矿质量比为6:4时，合成了单一的尖晶石型软磁铁氧体相；采用酸浸预处理红土镍矿，当两种矿质量比为7:3时，合成了单一的尖晶石型软磁铁氧体相。随着非磁性离子Al和Cr离子的掺杂，在铁氧体结构中占据了八面体B位，导致铁氧体的饱和磁化强度在减小；而随着磁性Ni、Co、Mn掺杂量的增加，在铁氧体结构中占据八面体B位，导致饱和磁化强度在增大。非磁性Zn离子掺杂到铁氧体，会占据四面体A位，当掺杂量＜0.4时，导致饱和磁化强度在增大，当掺杂量继续增加，由于四面体A位磁性离子大幅减少， A-B作用减弱， B-B作用增强，八面体B位磁矩会减小，最终导致饱和磁化强度在减小。杂质SiO2对合成纯铁氧体样品的结构和磁性能也有一定的影响。由于在磁性粒子表面形成非磁性SiO2壳状结构，致使在退磁的过程中所需能量减小，导致磁性铁氧体材料矫顽力的减小。本项目的研究结果有望为多金属共伴生矿产资源高效清洁高值化利用及矿相重构制备软磁铁氧体材料提供理论基础和技术支撑。通过本项目的研究共发表学术论文6篇，其中SCI论文4篇，参加学术会议5次，培养硕士研究生2名，晋升副教授1名，入选三晋英才1人，获得山西省科学技术合作奖一等奖1项。