Investigation of the leaching conditions of sulfide copper concentrate in acidic medium under the effect of oxidizing agent and solvent extraction

The chalcopyrite concentrate used in this thesis was taken from ETI Bakir flotation plant (Siirt, Turkey). In the first system, the addition of 2-propanol as an organic compound and NaCl as an inorganic substance in hydrochloric acid with hydrogen peroxide as a strong leaching agent was investigated. The influence of the leaching parameters on copper extraction, such as stirring speed, temperature, H2O2 concentration, HCl concentration and solid/liquid ratio were studied. The maximum final copper extraction of 54.55% was gained with 600 rpm stirring speed, 0.5 M HCl, 2 M H2O2, 50°C, 240 min of the reaction and -106 +75 µm particle size fraction. Further experimental tests were carried out when the solid/liquid ratio (S/L), temperature, stirring speed, HCl concentration, H2O2 concentration and leaching time were kept constant to examine the effect of 2-Propanol and NaCl concentration in the range of 0-3 M and 0 – 0.5 M, respectively. The results showed that the copper extraction was increased up to 58.11% with addition of NaCl. While copper extraction recovery reached 94.25% in case of addition of 2-propanol. The chalcopyrite leaching in hydrochloric acid–hydrogen peroxide system was found to be described by the interface transfer and diffusion across the product layer with activation energy of 77.14 kJ/mol. Addition of 2-propanol suggested that the reaction was diffusion control by product layer and decreased the activation energy of chalcopyrite leaching to 67.98 kJ/mol. In the second system, the effect of acetic acid and ethanol as polar aqueous solvents on sulfuric acid with hydrogen peroxide as an oxidant was studied. A small amount of this polar aqueous solvents significantly improved the copper leaching recovery. The leaching parameters such as temperature, stirring speed, H2O2 concentration, solid/liquid ratio, H2SO4 concentration and particle size were examined. 76.33% as highest Cu extraction was gained with 2 M H2O2, 600 rpm stirring speed, 50°C, 1 M H2SO4, 240 h of the reaction and -75+53 µm particle size fraction. Further experimental tests were carried out when the stirring speed, solid-to-liquid ratio (S/L), particle size, H2O2 concentration, temperature and H2SO4 concentration were kept constant to investigate the effect of ethanol and acetic acid concentration in the range of 0–2 M. The experimental results proved that the copper extraction recovery reached to 99.03% in 180 min of the reaction with 2 M acetic acid. While 2 M of ethanol increased copper extraction recovery up to 100% in 90 min of the reaction. The dissolution reaction found to be described by mixed kinetic model and activation energy of 54.37 kJ/mol. Addition of acetic acid and ethanol suggested that reaction was controlled by diffusion across product layer. In solvent extraction studies, a sulfate solution obtained from leaching experiments conducted with 1 M sulfuric acid at 50 °C was used. The purpose is to separate the copper from this solution by solvent extraction using LIX-984N. In the experimental studies, the effect of pH value, O/A ratio, diluent type and the extractant concentration on Cu extraction was investigated. While the effect of each parameter was examined, the other parameters were kept constant. The results obtained from the experimental studies showed that as the equilibrium pH increased, the amount of Cu in the organic phase increased. As the O/A ratio increases, the amount of Cu++ in the organic structure increases. As the volumetric percentages of the extractants increase from 3% to 9%, the amount of Cu in the organic phase also increases. As the H2SO4 concentration increases, the stripping efficiency increases.