褐铁型红土镍矿硫酸高压浸出矿物结构变化

Change of Mineral Structure before and after High-pressure Sulfuric Acid Leaching of Low-grade Laterite Nickel Ores

菲律宾某矿区典型褐铁型红土镍矿的工艺矿物学分析表明,矿样中主要的矿物为针铁矿、铬尖晶石、石英及其他黏土质矿物,镍、钴主要赋存在铁矿物中。基于矿物特性,选择采用硫酸高压浸出工艺对该矿物进行处理,在100 g矿酸用量29 g、温度250℃、液固比3 mL/g、反应时间30 min的条件下,镍、钴浸出率均超过95%,铁浸出率低于1%,实现了镍、钴的选择性浸出。浸出渣的工艺矿物学分析表明,浸出过程中,原矿中的针铁矿矿相被破坏,赋存在其中的镍、钴被浸出进入溶液,未被浸出的镍、钴赋存于铬尖晶石中,这是镍、钴浸出不完全的主要原因。浸出渣中主要的含硫物相是铝水解生成的明矾石和铁水解夹带的部分硫酸镁等硫酸盐,二者均与铁矿物结合较紧密。

The nickel laterite ore from a mine in Philippines was analyzed for systematic process mineralogy.The results show that the ore sample contains 44.83%iron,1.96%silicon,1.18%magnesium,1.02%nickel and 0.12%cobalt.It is a typical limonitic lateritic nickel ore.The main minerals in the samples are goethite,chrome spinel,quartz and other clay minerals,nickel and cobalt are mainly in iron minerals,and also in other minerals,and no nickel and cobalt minerals exist independently.Based on the characteristics of the minerals,the high-pressure sulfuric acid leaching process was chosen to treat the minerals.The leaching rate of nickel and cobalt is both 95%above,and the leaching rate of iron is less than 1%under the conditions including acid dosage of 29 g for 100 g mineral,temperature of 250℃,liquid-solid ratio of 3 mL g,and reaction time of 30 min,which realizes the selective leaching of nickel and cobalt.The process mineralogical analysis of the leaching residue was carried out to analyze the causes of incomplete leaching of nickel and cobalt.During the leaching process,the acicular ferrite mineral phase in the raw ore is destroyed,and the nickel and cobalt endowed in it are leached into the solution,while the nickel and cobalt that are not leached are deposited in the chrome spinel,which is the main reason for the incomplete leaching of nickel and cobalt.The main sulfur-containing phase in the leaching residue is alunite produced by aluminum hydrolysis.In addition,the leaching slag may also contain part of the sulfate such as magnesium sulfate,both of which are closely combined with iron minerals.The sulfur-containing minerals in the leaching residue are tightly bound to iron minerals,so chemical desulfurization is required to remove the sulfur and realize its comprehensive utilization.