Leaching behavior of cadmium from hazardous waste

作者：Gharabaghi Mandi^*; Irannajad Mehdi; Azadmehr Amir Reza

来源：Separation and Purification Technology, 2012, 86: 9-18.

DOI：10.1016/j.seppur.2011.10.014

• Hazardous waste
• Leaching kinetics
• Shrinking core model
• Diffusion

Solid residues from hydrometallurgical zinc plants contain high concentrations of heavy metals such as zinc, cadmium and nickel, and these residues are considered as hazardous waste. Recovery of cadmium from this waste using sulfuric acid leaching has been studied. It was found that the cadmium extraction rate increased by increasing acid concentration, stirring speed and temperature and decreasing solid-to-liquid ratio and particle size. The dissolution kinetics at 25-75 degrees C was found to follow shrinking core model, with activation energy of 7.21 kJ/mol, which was characteristic of a diffusion controlled process. The orders of reaction with respect to important parameters were obtained, and the rate of reaction was proposed as follows:
1 - 3(1 - alpha)(2/3) + 2(1 - alpha) = 0.63[H2SO4](1.35) (d)(-0.238) (S/L)(-0.76) (SS)(0.58) exp (-7.23/RT)t
The XRD and SEM analysis confirmed the leaching mechanism, and the results showed that the final residue can be used in other industries, and recycling is a sustainable approach for this waste management.

• 出版日期2012-2-15