镍黄铁矿与蛇纹石的磁罩盖分离强化机制研究

A novel method, selective magnetic coating technology, is proposed to separate the pentlandite mineral from serpentine, which is difficult for flotation to separate them. The magnetic seeding of magnetite can selectively coat on the surfaces of pentlandite to enhance its magnetism. Then, the pentlandite is separated from serpentine by magnetic separation. The dispersion and magnetic coating behaviors are studied with adding different dispersants and coagulants to determine the optimal reagents, which realize the dispersion between magnetic seeding and serpentine particles and strengthen the selective magnetic coating of magnetic seeding coating on the pentlandite surfaces. Then, the adsorption behaviors between reagents and minerals are investigated by directly using Zeta potential analyzer, spectrophotometer, ICP and FTIR and so on. Agglomeration behaviors of magnetic seeding coating on the mineral of interest are performed with a laser particle analyzer, SEM, XRD, and VSM and so on. Finally, dispersion and agglomeration mechanisms of the magnetic seeding are constructed by means of crystal chemistry, solution chemistry and surface chemistry. Therefore, processes of minerals dispersion, selective magnetic coating of magnetite and magnetic separation of minerals are clearly understood. Based on the above research results, the pentlandite mineral is sufficiently separated from serpentine through the magnetic coating tests.

针对镍黄铁矿和蛇纹石浮选难分离的问题，率先提出采用磁罩盖技术对上述矿物进行分离，使磁种磁铁矿选择性罩盖在镍黄铁矿表面，增强其磁性，之后通过磁选实现两种矿物的分离，不同于传统的浮选分离。首先通过研究添加不同分散剂和团聚剂时磁种与上述两种矿物在溶液中的分散和磁罩盖行为，甄选出有效的分散剂和团聚剂，从而实现磁种与蛇纹石间的分散以及强化磁种在镍黄铁矿上的选择性罩盖；然后利用Zeta电位、分光光度计、ICP、红外光谱检测等技术研究药剂与矿物的吸附行为；借助扫描电镜、激光粒度仪、X射线衍射分析、振动样品磁强计等技术研究磁种与矿物的罩盖行为的变化；最后结合晶体化学、溶液化学、表面化学等相关理论阐明磁种与非目的矿物的分散和磁种在目的矿物上罩盖的强化机制，从而更清晰的认识上述矿物磁罩盖分离时矿物分散、磁种选择性罩盖和矿物磁分离等过程。基于上述研究成果，最终通过磁罩盖分离试验，实现镍黄铁矿和蛇纹石的磁分离。

本项目针对中镍黄铁矿和蛇纹石难以分离的问题，提出采用“磁罩盖法”对其进行磁分离。以蛇纹石和镍黄铁矿为研究对象，以微细粒磁铁矿作为磁种，研究了不同分散剂和团聚剂对蛇纹石、镍黄铁矿单矿物及人工混合矿的磁罩盖磁选行为影响。结果表明，添加分散剂六偏磷酸钠之后，磁铁矿对蛇纹石的罩盖作用大大减弱，提高了磁铁矿对镍黄铁矿罩盖的选择性。添加团聚剂油酸钠后，进一步强化了磁铁矿在镍黄铁矿表面上的罩盖作用。.运用分子动力学模拟（MS）研究了药剂与矿物表面的吸附作用及吸附形态。结果表明，六偏磷酸钠垂直吸附在蛇纹石表面，增加了六偏磷酸钠吸附层的厚度，从而显著地增强了蛇纹石颗粒间的空间位阻作用，使颗粒处于更好的分散状态；油酸钠以平铺的形式吸附在镍黄铁矿和磁铁矿表面，在它们表面形成疏水吸附层，产生了强烈的疏水吸引作用，增强了磁铁矿与镍黄铁矿颗粒间的团聚。.通过MS、XPS分析了表面活性剂在矿物表面的吸附位点。结果表明，六偏磷酸钠与蛇纹石作用方式有两种：1）与从蛇纹石表面溶出的Mg2+发生络合，形成可溶的稳定络合物，从而造成蛇纹石表面电位急剧下降，颗粒间静电斥力增强而分散；2）与蛇纹石表面裸露的Mg-O活性基团中Mg作用而在其表面形成吸附物，导致蛇纹石的亲水性增强而被分散。油酸钠通过与镍黄铁矿表面的Fe、Ni原子作用而吸附在其表面，增强镍黄铁矿表面的疏水性；同时，油酸钠通过与磁铁矿表面的Fe原子作用而吸附在其表面，进而增强磁铁矿表面的疏水性，最终促进磁铁矿与镍黄铁矿的疏水团聚。AFM测试结果显示，在磁罩盖分选过程中，添加六偏磷酸钠后，磁铁矿与蛇纹石颗粒间的作用距离大幅缩短，颗粒间引力也大幅减小，减弱了磁铁矿与蛇纹石颗粒间的罩盖效果；在磁罩盖分选过程中添加油酸钠后，磁铁矿与镍黄铁矿颗粒间的作用距离大幅增加，颗粒间引力有所增加，增强了磁铁矿与镍黄铁矿颗粒间的罩盖效果。