Electrochemical Behavior of Nickel Laterite Ores Dissolution in Sulphuric Acid Solutions

Hydrometallurgical process of laterite nickel ore is carried out by leaching techniques at high temperatures. At atmospheric temperatures, the acquisition of nickel is low. Therefore, this study aims to characterize the electrochemical laterite nickel ore using a solution of sulfuric acid and hydrochloric acid at atmospheric temperature. Sulfuric and chloride acid solutions were used with solution concentrations of 1 M, 2 M, 4 M and 6 M. The study was carried out by sample and solution preparation, characterization by SEM-EDAX and Petrography method, and electrochemical characterization using the OCP, EIS method and LSV. The characterization results showed that the highest dissolution rate in both solutions was obtained at a concentration of 6 M solution. Increased concentrations of sulfuric acid reduced the value of OCP testing, while an increase in the concentration of hydrochloric acid increased the value of OCP. The EIS test results showed that the lowest R2 or Rct value in sulfuric acid solution was obtained at 2M concentration of 269.59 Omega while in hydrochloric acid solution it was obtained at a concentration of 6M of 523.07 Omega. The results of the second LP acid solution showed the formation of a passive layer at each concentration. The highest dissolution rate occurred at a concentration of 6M in each solution where the corrosion rate of sulfuric acid was 1.00 mm / year, while in hydrochloric acid it was 9.55 mm / year. Increasing the concentration of the two solutions led to the breakdown of the passive layer on the surface which can be seen from the Nyquist curve, the value of R2 is lower, the value of Q1 is higher and the value of N is lower, but in the sulfuric acid solution the formation of passive layers returns to increasing concentration starting from 4M. The three electrochemical tests show an increase in concentration to the optimum concentration increasing the dissolution rate and breaking the passive layer on the surface.