Integration for sulfur dioxide removal from smelting flue gas with copper tailings utilization and copper recovery via absorption-synchronous leaching and reduction

SO2 removal and copper tailings disposal became a challenge for the cleaner production of copper smelter. In this study, a novel SO2 removal process using copper tailings coupled with copper recovery was proposed, a pilot-scale device was set up, and an economic evaluation was conducted. Effects of factors including temperature, ratio of solid to liquid (S/L ratio), and flow rate on SO2 removal along with copper recovery were investigated. Results showed that influencing factors for SO2 removal were ranked flow rate > O2 concentration > temperature > S/L ratio. The entry of dust from flue gas slightly reduced the SO2 removal capacity from 193.74 to 171.56 mg/g, while the Cu2+ content in the slurry increased from 265.98 mg/L to 1172.45 mg/L with the introduction of 2.5 wt % dust. A 24 h pilot-scale test from a real copper smelter flue gas verified that the process simultaneously achieves SO2 removal and Cu2+ leaching. Additionally, Cu was recycled from slurry using iron powder as a reductant. X-ray fluorescence (XRF), X-ray diffractometer (XRD), and waste solid property characterizations revealed that the main mineral structures of copper tailings remained unchanged, while copper and arsenic were enriched in the precipitate from the slurry. Economic evaluation proved that the method significantly increased economic benefit. This approach achieves SO2 removal and realizes copper recovery, providing a scientific and engineering basis for the low concentrations of SO2 removal and copper tailings disposal in the copper smelter.