Atmospheric acid leaching is widely used to extract nickel from secondary resources due to its mild effect, but the extraction efficiency of nickel still remains limited. In this work, a sulfuric acid curing process was developed to improve the extraction of nickel by treating the leaching residues after acid leaching. The factors influencing the extraction of nickel from sintered alloy have been systematically studied based on thermodynamic calculations. The results show that the extraction of nickel reached 80.34 % after acid leaching under the optimized conditions. Reaction kinetic studies indicate that the leaching process was governed by a combination of the mixed control model (0–60 min) and the surface chemical reaction control model (60–100 min), with the apparent activation energies of these two stages determined as 33.32 and 67.07 kJ/mol, respectively. The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses indicate that the NiO coated by Ni₂O₃ in the sintered alloy and NiO passivation films generated during the acid leaching process hindered further dissolution of metallic nickel. The nickel oxides and passivation films could be transformed into water-soluble NiSO₄ after sulfuric acid curing with 60 % H₂SO₄ solution at 140 ℃. The overall extraction efficiency of nickel can reach as high as 99.13 % by using the two-stage leaching developed. This work provides a feasible and highly efficient approach to extract nickel from sintered alloy.

常压酸浸由于其作用温和，被广泛用于二次资源中提取镍，但镍的提取效率仍然有限。在这项工作中，开发了一种硫酸固化工艺，通过处理酸浸后的浸出残渣来改进镍的提取。基于热力学计算，系统地研究了影响烧结合金中镍提取的因素。结果表明，在优化条件下酸浸后镍的提取率达到80.34%。反应动力学研究表明，浸出过程受混合控制模型（0-60 min）和表面化学反应控制模型（60-100 min）的组合控制，这两个阶段的表观活化能确定为33.32和 67.07 kJ/mol，分别。X 射线光电子能谱 (XPS)、X 射线衍射 (XRD) 和扫描电子显微镜结合能量色散 X 射线光谱 (SEM-EDS) 分析表明，Ni 包覆的 NiO_{烧结合金中的2} O ₃和酸浸过程中产生的NiO钝化膜阻碍了金属镍的进一步溶解。经140 ℃ 60 % H ₂ SO ₄硫酸固化后，氧化镍和钝化膜可转变为水溶性NiSO _{4 。}采用所开发的两级浸出，镍的整体提取效率可高达99.13%。这项工作为从烧结合金中提取镍提供了一种可行且高效的方法。