الفهرس 
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Abstract
The main objective of the present study is twofold, first is to investigate the leaching kinetics of copper from a spent catalyst in a batch agitated vessel under the effect of different variables. The second is to examine copper recovery from synthetic leach liquor by electro deposition at a rotating square cylinder cathode. To this end, the following parameters were investigated in leaching step: i. Nature of acid. ii. Acid concentration. iii. Stirring speed. iv. Liquid/solid ratio v. Particle size of spent catalyst. vi. Solution temperature. Whereas the following variables were studies in the electrodeposition step: i. Rotating square cathode speed. ii. Initial CuSO4 concentration. The present study revealed the following conclusions: H2SO4 was found to be the best leaching agent. The rate of leaching was found to increase with increasing acid concentration, stirring speed, l/s ratio and temperature. Grinding of spent catalyst before leaching was found to enhance the rate of leaching considerably. Activation energy calculations exhibited a value of 8.79 kj/mol. This value indicated the diffusion controlled nature of the leaching step Mathematical treatment of the present leaching data using shrinking core model (SCM) revealed that the present kinetic data is well described by the diffusion controlled through ash layer rather than chemically controlled reaction and liquid diffusion. The rate of copper recovery by electrodeposition was expressed in terms of the mass transfer coefficient. It was found that the mass transfer coefficient increases with increasing rpm of the square rotating cylinder cathode, while it decreases with increasing initial copper sulphate concentration. The cylinder rotation not only increases the rate of copper deposition but also but also decreases the electrical energy consumption (kWh/kg) energy consumption under the present conditions ranged from 1.181 to 1.659 kWh/kg. The present mass transfer data for copper deposition under constant current electrolysis at square rotating cylinder was correlated using the method of dimensional analysis according to the following equation: for the conditions 657 < Re< 2373 , 2165.21< Sc <2819.2