The selective extraction of chromium (Cr) from Chromium-bearing electroplating sludge (CES) has positive significance for harmless disposal and reducing dependence on native resources. Herein, the process of pressure oxidation alkaline leaching of CES is reported. The leaching ratio of Cr was reached 89.9 % under the optimal conditions, i.e., temperature of 125℃, NaOH concentration of 1.5 mol/L, liquid-solid ratio of 10, oxygen partial pressure of 2Mpa and reaction time of 2 h, while other elements such as Cu, Ni, Fe and Zn were virtually not leached out. In addition, the concentration of NaOH required for the maximum of the leaching ratio of Cr decreased with the increase of temperature, which attributed to the synergistic effect of temperature and NaOH concentration on the solubility and diffusion coefficient of the oxidant. As the oxygen partial pressure was increased to 2 MPa, the liquid-solid ratio was raised to 10, and the reaction time was extended to 2 h, respectively, the leaching ratio of Cr reached maximum and then remained as a constant. Kinetic studies showed the leaching process of chromium was controlled by chemical reaction, and the apparent activation energy was 112.1 kJ/mol. The efficient selective recovery of Cr is of great significance to reduce the difficulty of comprehensive recovery of valuable metal elements in the CES.

中文翻译：

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加压氧化碱浸法选择性萃取含铬电镀污泥中的铬


从含铬电镀污泥 （CES） 中选择性提取铬 （Cr） 对于无害化处置和减少对原生资源的依赖具有积极意义。本文报道了 CES 的压力氧化碱性浸出过程。在温度 125°C、NaOH 浓度 1.5 mol/L、液固比 10、氧分压 2Mpa、反应时间 2 h 的最佳条件下，Cr 的浸出率达到 89.9 %，而 Cu、Ni、Fe 和 Zn 等其他元素几乎没有浸出。此外，Cr 浸出比最大所需的 NaOH 浓度随着温度的升高而降低，这归因于温度和 NaOH 浓度对氧化剂溶解度和扩散系数的协同作用。当氧分压增加到 2 MPa，液固比提高到 10，反应时间延长到 2 h 时，Cr 的浸出比达到最大值，然后保持恒定。动力学研究表明，铬的浸出过程受化学反应控制，表观活化能为 112.1 kJ/mol。Cr 的高效选择性回收对于降低 CES 中有价金属元素的综合回收难度具有重要意义。