A study of factors influencing the kinetics of copper cementation during atmospheric leaching of converter matte
The kinetics of copper cementation during atmosphere leaching of a Ni-Cu matte in CuSO4-H2SO4 solution was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate, particle size distribution and pulp density. It was found that all these process variables influenced the rate of cementation. A two-stage rate of reaction was observed in most of the experiments, with the rate of cementation in the initial stage being slower than that of the subsequent second stage. The increased rate of cementation in the second stage was attributed to the enhancing effect of the surface deposit. The cementation process was found to take place by two different rate-controlling mechanisms. At a temperature range of 50i?½70i?½C, an activation energy of 74.6 kJ/mol was obtained, indicating a surface reaction controlled process. At higher temperatures (70i?½80i?½C) a lower value of activation energy was observed (18.2 kJ/mol), indicative of a process controlled by diffusion through surface layers. The structural characteristics of the cemented deposit could not be determined in the investigated system where the deposit was mixed with the leach solid residue.
INVESTIGATION OF COPPER CEMENTATION KINETICS BY ROTATING ALUMINUM DISC FROM THE LEACH SOLUTIONS CONTAINING COPPER IONS
Recovery of metallic copper from the leach solution containing copper (II) ions by cementation process using aluminum disc has been examined. Solutions obtained from the leaching of malachite in aqueous acetic acid solutions were used in the study. It was determined that the cementation rate increased with increasing solution concentration, temperature and rotating speed, and decreasing solution pH. The reaction rate fits to the first order pseudo homogeneous reaction model and is controlled by diffusion. The activation energy of this process was calculated to be 32.6 kJ/mol.
The effects of kinetic variables on the structure of copper deposits cemented on pure aluminum discs: A scanning electron microscopic study
Abstract The structural characteristics of copper deposits resulting from copper cementation on pure aluminum are presented. The effect of chloride ion concentration, rotational speed of the aluminum disc, hydrogen ion concentration, copper ion concentration, and temperature on the nature and morphology of the deposits was investigated. Different copper deposit structures, viz. bulbous, massive crystalline, thick dendrites with leaf-like secondary arms, and dendrites of different degrees of fineness and texture were observed in the present study utilizing the scanning electron microscope. Deposit morphology was greatly modified for variations of chloride ion up to 25 mg l−1 and for increases in temperature up to 40° C. The maximum rate of copper cementation on pure aluminum was usually associated with a fine, dendritic structure.