An Innovative Approach to Separate Iron Oxide Concentrate from High-sulfur and Low-grade Pyrite Cinders

摘要

High-sulfur and low-grade pyrite cinders are the waste products of sulfuric acid manufacturing plants. Many valuable components,such as iron oxide,are contained in pyrite cinders and difficult to be separated and puri-fied j ust via the high temperature roasting process.Considering this,an innovative method including water-washing, aqua regia leaching,hydrothermal alkali activation and acid-washing was developed.And the effects of different pa-rameters on recovery efficiency of iron oxide were systematically investigated.The optimum parameters were pro-posed as follows:water rinse-leaching at room temperature for 5-20 min,and melting at 160 ℃ for 2.0 h with NaOH (concentration of 30 mass%),followed by leaching with aqua regia solution (3.0 vol.%)for 1.0 h.After the treatment,the content of iron oxides increased from 54.3 to 96.0 mass% with the recovery rate exceeding 85%. Meanwhile,calcium sulphate was recovered as the high value-added products by alkali extraction liquid.Further-more,the phase transformation and microstructure of the samples in the process were studied by physicochemical methods to reveal the separation mechanisms of different components in the pyrite cinders.