LEACHING STUDY OF NICKEL PIG IRON (NPI) POWDER IN SULFURIC ACID MEDIUM AT ATMOSPHERIC PRESSURE USING HYDROGEN PEROXIDE AS OXIDIZING AGENT

• Main Author: Sucipto, Nurfauziah
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69373
• Institution: Institut Teknologi Bandung

Nickel pig iron (NPI) is ferronickel with a lower nickel content, and most of it is further processed into stainless steel. In an effort to meet the nickel demand for the battery industry, NPI can be utilized by extracting nickel and cobalt, as well as iron which can be processed into iron phosphate for the cathode of LiFePO4 type lithium-ion batteries. Meanwhile, nickel and cobalt can also be further processed into pure nickel sulfate and cobalt sulfate as raw materials for NMC type battery cathodes. In this research, metal extraction from NPI powder was studied by leaching method in acid solution using H2O2 as oxidizing agent A series of agitated leaching experiments at atmospheric pressure were carried out to study the effect of acid type, acid concentration, leaching temperature, solid/liquid ratio (S/L ratio), leaching kinetics, and length of time for adding hydrogen peroxide on the extraction percentages of Fe, Ni, and Co metals. The leaching kinetics were studied at a concentration of 3 molars sulfuric acid, 12 ml H2O2, and agitation speed of 250 rpm at 70, 80, 90, and 100 .oC.. Each leaching process was carried out for 3 hours based on the experimental results in the previous study. The percentage of the dissolved metal as a function of time under various leaching conditions was periodically determined by atomic absorption spectrophotometry (AAS) analysis. The dissolution kinetics of NPI powder is approximated by the shrinking core and shrinking particle models. From the data of reaction rate constants or diffusion coefficients at various temperatures, the activation energy of NPI powder leachate was determined. The metal extraction percentage increased at 2 M to 3 M sulfuric acid concentrations, then decreased at 3.5 M increments. As the leaching temperature increased, the metal extraction percentage also increased and decreased as the S/L ratio increased. The highest metal extraction percentage was obtained at 3 M sulfuric acid concentration, operating temperature 100 , particle size fraction - 65+100#, S/L ratio 25 g/L, stirring speed 250 rpm, after 3 hours which resulted in Fe extraction percent of 95.77%, Ni is 96.13%, and Co is 100%. The leaching rate of NPI powder in sulfuric acid solution with hydrogen peroxide as an oxidizing agent with shrinking core model analysis was controlled by the diffusion of the fluid film with an activation energy value of 19.11 kJ/mol, while in the shrinking particle model analysis, the NPI leaching rate was controlled by a chemical reaction with a value of activation energy 25.04 kJ/mol. The addition of hydrogen peroxide as an oxidizing agent increased the extraction percent of Fe and Ni metals, but in Co metal there was a decrease in the extraction percent at a higher hydrogen peroxide concentration which was thought to occur due to the oxidation of Co to Co3+ which had lower solubility.