After recovering rare earth from neodymium–iron–boron (Nd–Fe–B) magnet waste via oxidation roasting–hydrochloric acid leaching, extracting rare earths and cobalt from remaining leach residue, containing about 0.67% (w/w) RE and 0.36% Co, is environmentally and economically important. However, extracting valuable elements from low–grade minerals remains challenging. The purpose of this study is to accelerate the dissolution of rare earths and cobalt from leach residue of Nd–Fe–B waste (MWLR) under low acidity by adding iron as a reductant, which is conducive to destroying the main phase iron oxide. To optimize the leaching process of MWLR in a sulfuric acid system, the effects of reaction temperature, reaction time, sulfuric acid dosage, solid/liquid (S/L) ratio, reductant addition time and reductant dosage were investigated. Circa 87.9% Fe, 99.7% Co, 99.4% Nd, 73.2% Pr and 87.9% Ce were leached. Furthermore, kinetic results indicated that the leaching process, controlled by a combination of internal diffusion and surface chemical reaction, changed to a surface chemical reaction control in the presence of Fe added as the reductant. This research proposed and verified a way to extract low–grade rare earths and cobalt from MWLR, and investigated the mechanism of reductive leaching process.

钕铁硼（Nd-Fe-B）磁铁废料经氧化焙烧-盐酸浸出回收稀土后，从剩余浸出渣中提取稀土和钴，含稀土约0.67%（w /w）和0.36% Co 对环境和经济都很重要。然而，从低品位矿物中提取有价值的元素仍然具有挑战性。本研究的目的是通过添加铁作为还原剂，加速稀土和钴在低酸度下从钕铁硼废料（MWLR）浸出渣中溶解，有利于破坏主相氧化铁。为优化 MWLR 在硫酸体系中的浸出工艺，反应温度、反应时间、硫酸用量、固/液 ( S / L)的影响考察了还原剂添加时间和还原剂用量。大约 87.9% Fe、99.7% Co、99.4% Nd、73.2% Pr 和 87.9% Ce 被浸出。此外，动力学结果表明，在作为还原剂添加的 Fe 存在下，由内部扩散和表面化学反应控制的浸出过程变为表面化学反应控制。本研究提出并验证了一种从MWLR中提取低品位稀土和钴的方法，并研究了还原浸出过程的机理。