چكيده به لاتين
Among the various industrial wastes, the spent catalysts used in the petrochemical industry contain heavy metal compounds, and the disposed of these metals is hurmful for environment spent, furthermore petrochemical catalysts can be considered significant secondary resources because of its rare metal content. Therefore many of researchers has been attracted to development processes to recovery of this valuable metals, Hydrometallurgy recovery has been considered as an environmentally friendly method for some reason, including low energy consumption and reduction of environmental pollution. In the present work spent catalyst Mo, V, Ni /Al2O3 has been studied. then in order to recovery valuable metal leaching test was performed in oxalic acid and hydrogen peroxide agent. This process was studied using a 3 level design with 4 repetitions to describe the effect of variables, leaching temperature and leachant concentration. The concentrate from each test were analyzed to determine Ni, V, Mo, Al content as well as Ni, Mo, V and Al recovery as response variables. From statistical analysis of data, a polynomial model was fitted to each response and by numerical optimization, (H2C2O4 concentration of 1. 5mol/L, leaching temperature of 80 °C, solid -to- liquid (S/ L) ratio of 2 g/L, speed of stirrer 800 rpm and leaching time of 3 h) 72% of Mo, 93% of V,43% Ni and 79% Al was dissolved into the liquid phase and Under the optimal leaching conditions (H2O2 concentration of 1/5 mol/L, leaching temperature of 70 °C, solid -to- liquid (S/ L) ratio of 2 g/L, speed of stirrer 800 rpm and leaching time of 3 h) 92% of Mo, 64% of V,83% Ni and 6% Al was dissolved into the liquid phase. Finally according to selective leaching with H2O2 solvent and insolubilization of alumina into the second solution with the goal of maximizing the dissolution of molybdenum and vanadium a two stage leaching was performed, first stage under optimal conditions in the oxalic acid solution and then the residual residue in the second solution, under optimum conditions in the hydrogen peroxide solution was leachate which resulted to dissolution of 99% vanadium and 96% molybdenum.
