Recovery and Enrichment of Platinum from Spent Al2O3 Carrier Catalysts by Matte Smelting-Acid Leaching Process

Abstract

Recovery of platinum from spent catalysts can meet the comprehensive recycling of secondary resources. Recovery and enrichment of platinum from the spent Al2O3 carrier catalyst using matte smelting for the pyrite-acid leaching process were studied. In melting process, the effects of pyrite, CaO, quartz sand, and Na2B4O7 dosage on the recovery rate of Pt were investigated. In leaching process, the effect of H2SO4 concentration, temperature, time, and liquid/solid (L/S) ratio on Pt enriching efficiency was also investigated. The slag, iron matte, and leaching residue were analyzed using XRD. The molten platinum content in the slag was measured using an atomic absorption spectrometer. The experimental results showed that 98% recovery of platinum was obtained under the following optimum conditions: 1400°C temperature, 50 min smelting time, 1 : 2 mass ratio of pyrite to spent catalysts, 0.5 : 1 ratio of CaO to spent catalysts, and 2 : 1 ratio of quartz sand to the raw material with optimum conditions, which include 15% dosage of Na2B4O7. Moreover, the acid leaching was more efficient under the following optimum conditions: H2SO4 concentration of 1.8 mol/L, time of 70 min, temperature of 60°C, and L/S ratio of 10 : 1. The enrichment and recovery of Pt were achieved at the disappearance of FeS during the acid-leaching process.