Chromium ore processing residue (COPR) is a hazardous waste generated during the production of chromate. Currently, approximately 10% of Cr₂O₃ cannot be extracted after chromite sodium roasting and remains in COPR, wasting valuable Cr resources. In this study, Mg was selectively removed by using (NH₄)₂SO₄ roasting in combination with H₂SO₄ leaching. The results showed that the selective removal of 79.55% Mg from COPR could be achieved under the optimum (NH₄)₂SO₄ roasting conditions (80 mmol (NH₄)₂SO₄, 800 °C, 2 h). During the subsequent sodium roasting and acid leaching stages, the Cr extraction rate was 84.63% for the COPR direct roasting and 95.39% for the Mg removal residue roasting. The increased Cr extraction efficiency is attributed to the transformation of Mg-rich spinel and diopside (the Mg & Cr coexisting phases) in COPR converted into easily extractable (Fe,Cr)₂O₃ and Cr₂O₃ after the Mg treatment. This study investigated that the phase transformation of the Cr host phases is crucial for the sufficient extraction of Cr and provides inspiration for the development of efficient and practical Cr extraction techniques. Moreover, the method can be extended to the effective extraction of Cr from other Cr-containing wastes.

铬矿加工残渣（COPR）是铬酸盐生产过程中产生的危险废物。目前，铬酸钠焙烧后约10%的Cr ₂ O ₃无法提取，残留在COPR中，浪费了宝贵的Cr资源。_{在本研究中，通过使用 (NH 4} ) ₂ SO ₄焙烧结合 H ₂ SO ₄浸出选择性去除镁。结果表明，在最佳(NH ₄ ) ₂ SO ₄焙烧条件(80 mmol (NH ₄ ) ₂ SO ₄, 800 °C, 2 小时)。在随后的钠焙烧和酸浸阶段，COPR直接焙烧Cr提取率为84.63%，除镁渣焙烧为95.39%。铬提取效率的提高归因于在 Mg 处理后 COPR 中的富镁尖晶石和透辉石（Mg 和 Cr 共存相）转化为易于提取的 (Fe,Cr) ₂ O ₃和 Cr ₂ O ₃。本研究调查了 Cr 主体相的相变对于 Cr 的充分萃取至关重要，并为开发高效实用的 Cr 萃取技术提供了灵感。此外，该方法可以扩展到从其他含铬废物中有效提取铬。