Leaching of Copper Ores: Effects of Operating Variables

Abstract

Leaching of copper from a Jordanian copper ore has been studied using a stirred batch reactor with hydrochloric acid as the main lixiviant, under the following conditions: temperature 25 -45 o C, acid concentration 0.05 -0.2 N, particle size 462 -1850 m, stirring speed of 700 -1000 rpm, and solid/liquid ratio of 1 -4 g/L. It was found that the rate of leaching of copper ore with hydrochloric acid or sulfuric acid, increases with temperature and acid concentration, while it decreases with increasing particle size. At the same operating conditions, leaching with sulfuric acid gave slightly greater conversion than leaching with hydrochloric acid, particularly at operating conditions of high temperature, high acid concentration, and small ore particle sizes. A maximum copper dissolution of about 87 % can be recovered at a leaching temperature of 45 o C, 462 m particle size, 0.2 N hydrochloric acid, 1.0 g/L solid to liquid ratio, and 1000 rpm stirring speed. Keeping all these operating parameters constant while decreasing the hydrochloric acid concentration to 0.05 N will decrease the copper dissolution to 83 %. On the other hand, decreasing the leaching temperature to 25 o C while keeping the other parameters fixed at 0.2 N, 1.0 g/L solid to liquid ratio, 1000 rpm stirring speed, and a particle size of 462 m decreases the copper dissolution to 80 %.

Kinetics of Hydrochloric Acid Leaching of Copper from its Ore

“…As previously shown [6], copper dissolution increases as the leaching temperature increases. Table 3 shows the effect of Figure 17 represents these two relations graphically, multiplying the obtained slope with the gas constant (1.987´10 -3 kcal⋅K −1 ⋅mol −1 ) gives the activation energies.…”

“…The influence of stirring speed, solid-to-liquid ratio, leaching temperature, acid concentration, particle size, and acid consumption on the rate of leaching of copper from its ores were presented and discussed in detail in the first article of this series [6]. The kinetics and fitting of the leaching process will be presented and discussed below.…”

“…A one-liter nominal capacity Pyrex glass rounded bottom flask with three necks carrying a thermometer, a stirrer, and a sampling device was used to run the leaching experiments [6].…”

“…In previous studies [5,6], the effects of leaching temperature, acid concentration, particle size, stirring speed, and solid/liquid ratio on the leaching process of copper ore using hydrochloric acid as the main lixiviant were studied and presented. The present work quantitatively investigates the kinetic mechanism of the leaching process of copper in hydrochloric acid solution, hence a theoretical background for the available heterogeneous reaction models will be presented here for heterogeneous reactions between fluid A and solid B, which may be represented by (#$%&') + + (-.$&') →…”