چكيده به لاتين
In this research, the experimental study and modeling of process parameters effective on simultaneous recovery of nickel, copper, zinc and cadmium metals from low-grade cold filter cake with leaching, solvent extraction and adsorption processes have been done. The cold filter cake obtained from zinc factory and its properties were evaluated by X-ray diffraction and X-ray fluorescence. In the leaching process and based on the response surface central composite design method, the effect of six effective parameters of temperature, time, solid-liquid ratio, particle size, air/ozone injection, and pH were investigated. The correlation coefficient for nickel, copper, zinc and cadmium are 0.9497, 0.9164, 0.9368 and 0.9837, respectively. 84.663% of nickel, 85.872% of copper, 74.862% of cadmium and 86.130% of zinc are recovered with sulfuric acid leaching at pH 2.5, during 2.5 h at 50 0C with 88 mic, solid to liquid ratio of 0.08 g/ml and without air/ozone injection. Solvent extraction and surface adsorption processes have been investigated in parallel in order to purify and separate the mentioned metals from the leaching solution. In the first step of the solvent extraction, 93.67% of zinc was extracted from the leaching solution with pH 4 by 20% D2EHPA in kerosene, for 20 min and the organic to aqueous ratio, 1:1. In the second step, 100% of copper was extracted from the raffinate of the first step with pH 2.3 by 10% Lix 5640 in kerosene, for 10 min and organic to aqueous ratio, 1:1. In the third stage, 88.61% of nickel was extracted from the raffinate of the second stage with pH 7 by 20% D2EHPA in kerosene, for 10 min and organic to aqueous ratio, 1:1. The stirring speed was 200 rpm and the ambient temperature was considered constant for all experiments. The simultaneous surface adsorption of nickel, copper, zinc and cadmium from the leaching solution with weak acid resin was studied by the response surface central composite design method, kinetic and thermodynamic modeling. The parameters of pH, time, temperature and the concentration of resin were investigated at five levels. The correlation coefficient (R2) for nickel, copper, zinc and cadmium is 0.9418, 0.9753, 0.9657 and 0.9189, respectively. The adsorption of all four metals is according to the pseudo-second-order kinetic model. The adsorption rate is 13.408, 7.087, 4.357 and 15.040 mg/g of nickel, copper, cadmium and zinc in 20 min, 30 0C, pH 5 and 4 g/l of resin.
