Advanced Treatment Of Low Concentrations Of Precious Metals Barren Solution By Electrochemical Method

During the energy shortage and environmental pollution problems, research the low concentration of precious metals barren solution processing have the significant effect to the precious metals industry. Electrochemical treatment of low concentration of precious metals barren solution was conducted using a new coal-based material as electrode. The influence factors of electrochemical procession and the technology parameters were studied for the reaction process, and discussed the reaction mechanism thoroughly. The pore size distribution measurement, electrochemical workstation and the scanning electron microscopy and energy spectrum were used to characterize the morphology, pore structure and the shape, load substances of plate after reaction with different time of the coal-based electrode material.The study shows that treated barren solution of 50 ml, when the voltage of 1.6v,reaction time of 6h, temperature of 50℃, plate spacing of 10 mm, the removal rate of Pd could reach 99.9%, and other precious metal ions had a certain remove effect too,the ions concentration were below 0.5mg/L after reaction. The orthogonal experiment shows that the influence degree of the treatment effect of the palladium ion from big to small in order were reaction time, temperature and voltage. Under the optimum condition from the orthogonal test, parallel experiments confirms that the removal rate of palladium ion reached 99.32%. Dynamics research result shows that the process conformed to the first order kinetics model, and the rate constant could reach 0.496s-1,means the reaction rate of whole electrochemical process was fast.The coal base electrode material has abundant pore structure and larger specific surface area but mainly composed of micropores, palladium ion in the barren solutionused in this experiment with a stability form of PbCl42-, it has strong adhesion ability on the surface but larger diffusion resistance in the internal channel of the electrode.In the electrochemical process, precious metal ions had been remove effectively under the electrolytic deposition and electric adsorption. The metal ions in the solution separated from the system interacted by electrolysis deposition in cathode and electric absorption in anode, the electrolysis deposition at cathode play dominant roles at beginning, with the cathode over-potential response to gradually reduce and adsorption reaction was not affected. Theoretical analysis shows that using electrochemical method processing of metal ions solution under a low voltage, due to the different metal ions in solution have the different properties, with the same device and condition, the running mechanism was different, pure electric adsorption technology only applies to separation recycling some simple metal ion in the solution,while the wastewater containing heavy metals, especially the complex ions with high relative molecular mass and a large quantity of electric charge, the ions in solution interacted by electric adsorption and electrolytic deposition process.