Recovery of indium from acidic leach solutions of spent LCD panels using ion exchange

Abstract

The recovery of indium (In) from spent LCD screens represents an avenue of interest to meet the growing market demand for this strategic metal. The main purpose of the present study was to evaluate the efficiencies of nine ion-exchange resins to selectively recover indium from synthetic and real leachates produced from the recycling of spent LCD screens. Under optimal leaching conditions ([H2SO4] = 0.2 M, pulp density = 50% w/v, T = 70 °C, t = 30 min), a leachate of indium concentration 102 ± 7 mg/L as well as other impurities such as Fe, Al, Ca was obtained. Among the resins tested, Lewatit VP OC 1026, a D2EHPA impregnated resin, was chosen for its selectivity towards other metals present in high concentrations in the leachate (Al, Ca, Fe). This resin was able to retain up to 34.6 and 27.2 indium (mg/g of resin) from the real leachate, during tests carried out at 25 and 70 °C, respectively. The elution of indium can be achieved: i) partially (78%) with a 1 M HCl solution and ii) completely with a 5 M HCl solution. A final indium solution of 242 ± 29 mg/L and less than 2 mg/L of other impurities (Fe, Al, Ca) was obtained at the end of the fixation/elution tests.