Perpustakaan Digital ITB

In the present study, the separation and recovery of nickel and cobalt from simulated pregnant leach solution by solvent extraction (SX) using PC-88A, LIX-84I and D2EHPA is investigated. The ore sample used in this study was limonite ore received from a mine area in Pomalaa, South East Province of Indonesia. Major dissolved metals in the leach solution considered were Fe, Mn, Co, Ni, and Mg. Preliminary leaching tests were conducted to obtain a typical leach composition from both ore types. Based on the preliminary experimental results, the sulfuric acid concentration required to obtain sufficient nickel and cobalt extraction percentages for limonite ore at 90oC and 6 hours are 3M. In order to have typical composition of leaching solution that have already been subjected to iron precipitation, series of precipitations experiments were also conducted by using ammonia solution as neutralizing agent. By pH adjustment, dissolved iron was selectively precipitated at pH 4, under which Ni, Co, Mn, and Mg were not co-precipitated. Series of SX experiments for separation and recovery of Co and Ni from simulated leach solution containing Ni, Co Mn and Mg were conducted by using PC-88A, LIX-84I, D2EHPA 10%v/v as extractant diluted in kerosene. The extraction experiments revealed that D2EHPA is suitable for manganese separation in which approximately 70% manganese is extracted and co-extraction of Co and Ni are only approximately 0.7-3% at pH 2.3-2.5. LIX-84I selectively extracts Ni, Co, and Mn and only slightly extracting Mg at equilibrium pH of 7 in which the co-extraction of magnesium was only approximately 4%. Nickel and cobalt extraction levels of higher than 99% can be obtained in single stage extraction by LIX-84I 10% v/v diluted in kerosene at equilibrium pH of 7, O/A = 1 and room temperature. The addition of TBP into PC-88A, LIX-84I, and D2EHPA resulted only a simultaneous shift of Mn, Ni, Co, and Mg extraction isotherm curves to higher pH. Nickel extracted by LIX-84I can be perfectly stripped from organic phase in two stages at pH 1 and O/A ratio of 2. Co-extraction of Mg can be removed easily from loaded LIX-84I, while manganese can be removed partially by scrubbing at equilibrium pH of 5-6. Cobalt extracted by LIX-84I cannot be stripped by sulfuric acid solution. A mixture of acetic-sulfuric acid solution with ratio of 1:2 to 1:6 can effectively strip cobalt from loaded LIX-84I with 95.42% stripping percentage at room temperature and A/O ratio of 1.