Microwave assisted atmospheric acid leaching of nickel from laterite ore

The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied. The experimental results indicated that the extraction rate of nickel was influenced by reaction time, sulphuric acid concentration, and temperature, especially by microwave power. The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration, reaction time, microwave power, and temperature were 25 vol.%, 1.5 h, 600 W, and 90 degrees C, respectively. Under the optimal conditions, the nickel recovery could reach approximately 90.8%, which was higher than that obtained by conventional water bath heating. Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore. The apparent activation energy was 38.9 kJ/mol. Microwave heating technology is efficient, clean, and easy to control and facilitate continuous processing of materials.