PURIFICATION OF PREGNANT LEACH SOLUTION FROM MIXED HYDROXIDE PRECIPITATE (MHP) LEACHING BY SOLVENT EXTRACTION USING A MIXTURE OF CYANEX® 272 AND IONQUEST® 290

• Main Author: S.H Sitanggang, Alfonso
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85271
• Institution: Institut Teknologi Bandung

In Indonesia, nickel production from low-grade laterite ore of limonite type is carried out through a high-pressure acid leaching (HPAL) process that produces an intermediate product in the form of MHP. To obtain nickel with higher purity, MHP requires further purification, which generally involves a solvent extraction (SX) process. One of the extractants commonly used in commercial MHP purification is Cyanex® 272 (C272). One alternative to C272 is Ionquest® 290 (I290), which has a higher purity of active components than C272. In this study, the purification process of MHP leaching solution with SX using a mixture of C272 and I290 extractants was studied. The purpose of this study was to determine the performance of SX with a mixture of C272 and I290 extractants, in terms of metals (Ni, Co, Mg, Mn, and Cu) extraction and separation of Ni from Co. A series of laboratory-scale experiments were conducted with an initial feed in the form of an artificial solution that simulates the MHP leach solution after the impurity removal stage using di(2-ethylhexyl) phosphoric acid (D2EHPA). The organic extractant used consisted of C272 and I290, both of which have the active component bis(2,4,4-trimethylpentyl) phosphinic acid, kerosene as a diluent, and tri-n-butyl phosphate (TBP) as a phase modifier. At the extraction stage, the influence of SX variables including equilibrium pH, extractant composition ratio, total extractant concentration (v/v), and organic/aqueous solution volume ratio (O/A) on metal extraction and separation of Co from Ni was studied. Following the extraction stage, the research proceeded to the scrubbing stage by varying the initial pH of the scrubbing agent and the O/A phase ratio. Subsequently, stripping experiments were carried out by varying the concentration of the stripping agent. The experimental results of the extraction stage revealed that the percentage of Ni, Co, Mg, Mn, and Cu extractions increased in line with the increase in equilibrium pH, total extractant concentration, and O/A phase ratio. The synergistic effect was found to affect Ni, Co, Mg, and Mn extractions, while the antagonistic effect was found in the extraction of Cu. The optimum conditions for the extraction stage were found at equilibrium pH = 5.5, extractant composition ratio I290:C272 = 20%:80%, total extractant concentration = 30%, and O/A = 1/3, with the extracted Ni, Co, Mg, Mn, and Cu of 12.05%, 97.56%, 57.26%, 99.18%, and 99.92%, respectively. In the scrubbing stage, the optimum conditions were obtained at the initial pH = 2 and O/A = 4, with the number of scrubbing stages = 4. The optimum stripping condition was obtained at the concentration of H2SO4 solution = 1 M and O/A = 1. The investigation results showed that extractants C272 and I290 can be used together in the SX circuit for the separation of Ni from Co.