Abstract: Paleo-terrestrial sedimentary rare earth ore is a new type of rare earth ore, the process produces a large amount of rare earth residue after acid leaching separation of rare earth elements. Al, Fe, and Ti present in the rare earth residue are important metals, and the separation and extraction of metal elements from the rare earth residue can improve the utilization value of rare earth ores and solve the solid waste disposal problems. Sulfuric acid solution was used to leach the residue from rare earth ore processing to investigate the effect and reaction mechanism of sulfuric acid solution on the leaching behavior of Al, Fe, and Ti. The results showed that the sulfuric acid solution could effectively dissolve silica-aluminate and hematite in the rare earth ores, selectively leach Al and Fe. In contrast, anatase did not easily react with the sulfuric acid solution, and the leaching rate of Ti was low, which stayed in the leaching residue together with Si. The optimal reaction conditions were optimized using one-way and orthogonal experiments, and the leaching rates of Al, Fe and Ti reached 86.44%, 94.00%, and 7.14%, respectively, under the optimal reaction conditions of reaction temperature of 115℃, reaction time of 6 h, acid residue mass ratio of 2.1 g/g and liquid-solid ratio of 4 g/g. It was found that the reaction temperature significantly affected the leaching rates of Al and Fe. Then (NH4)2SO4 was added to the leaching solution, and Al could be converted to NH4Al(SO4)2 crystals and precipitated, and Al2O3 was produced by roasting to realize the separation of Al and Fe. This study realized the selective recovery of Al and Fe elements in rare earth residue, and enriched Si and Ti elements in the leaching residue, which was conducive to the recovery of Ti elements in the next step.

Key words: paleo-terrestrial sedimentary rare earth ores, leaching residue, valuable metals, selective leaching

摘要： 古陆相沉积型稀土矿是一种新型稀土矿，对稀土矿浸出渣进行金属元素分离提取，可提高稀土矿的利用价值和解决固废处置难题。本工作采用硫酸溶液浸出稀土矿浸出渣，探究硫酸溶液对Al, Fe和Ti浸出行为的影响和反应机理。研究结果表明，硫酸溶液可以有效溶解稀土矿中的硅铝酸盐和赤铁矿，选择性地浸出Al和Fe，锐钛矿不易与硫酸反应，因此Ti的浸出率较低。通过单因素和正交实验优化反应条件，在反应温度115℃、反应时间6 h、酸渣质量比2.1 g/g和液固比4 g/g的最佳反应条件下，Al, Fe和Ti浸出率分别达到86.44%, 94.00%和7.14%。浸出液通过硫酸铝铵法可将Al和Fe有效分离，并制得Al2O3。

关键词: 古陆相沉积型稀土矿, 浸出渣, 有价金属, 选择性浸出