Study of the Kinetics of Copper Leaching from Solid Electroplating Sludge

In the process of wastewater treatment from electroplating industries, solid residues containing compounds of Fe, Cu, Ni, Zn, and other metals are generated. To determine the optimal leaching conditions for metals and identify the limiting stage of the process, an experimental study of the leaching kinetics was conducted, focusing on key technological parameters—temperature and the concentration of reacting substances. The kinetic parameters of the reaction were investigated using electroplating sludge containing up to 50% Fe compounds, 9.6% Cu compounds, ~1% Zn compounds, 0.5% Ni compounds, and less than 0.1% Cr, Pb, Cd, Mg, and Ca compounds. Sulfuric acid (H2SO4) with concentrations ranging from 0.15 to 0.75 M was used as the leaching reagent, in significant excess relative to the metal content. The process was carried out at a pH of the equilibrium solution that limits the dissolution of iron compounds and allows only the dissolution of nonferrous metal compounds. The concentration of copper in the leaching solution reached 17.8–18.1 g/dm3.