有色金属冶炼废水处理二次污泥中银的硫氰酸铵浸出动力学

Kinetics of silver-leaching with NH_4SCN for secondary sludge from nonferrous metal smelting wastewater

以硫氰酸铵作为浸银剂,从除砷提铜后的有色金属冶炼废水处理的二次污泥中提取银,研究了银的浸出过程动力学.结果表明,硫氰酸铵浸出银的过程符合收缩核动力学模型,浸出活化能Ea为14.87kJ·mol-1,扩散系数D′为2.3×10-5exp(-1 487/RT)cm0.5·mol 0.5·s-1.根据该模型可知,硫氰酸铵浸出银的决定步骤是固体膜扩散.

Ammonium thiocyanate was used as a silver-leaching agent to extract silver from ar- senic-free anode sludge （secondary sludge） coming from nonferrous metal smelting wastewater. The kinetics of the silver-leaching process from the treated secondary sludge was studied. Results indicate that the leaching process of silver by ammonium thiocyanate can be described with the unreacted core contracting model, and corresponding leaching activation en- ergy is 14.87 kJ ~ mol-1 and diffusion coefficient D＇ is 2.3 × 10-5 exp（- 1 487/RT） cm^0. 5. molo. s · s-1. According to the model, it can be inferred that the leaching reaction rate is mainly deter- mined by the solid membrane diffusion rate.