草酸-硫酸体系协同浸出硫铁矿渣中铁的机理及工艺优化

To address the low recovery ef f iciency of iron resources f rom pyrite cinder and the inef f iciency of conventional acid leaching methods, a synergistic leaching system of H2 C2 O4-H2 SO4 is proposed. The optimization of process parameters, such as leaching time, temperature, liquid-solid ratio, and sulf uric acid concentration, is perf ormed using response surf ace method. The synergistic leaching mechanism is analyzed through leaching kinetics and thermodynamics, and the morphology and phase compositions of samples before and af ter leaching are characterized. Results show that oxalic acid signif icantly enhances the iron leaching rate due to its strong complexation ability. The optimized H2 C2 O4 -H2 SO4 model, developed using response surf ace method, accurately predicts the leaching ef f iciency. Under the optimized conditions of 6 hours of leaching time, 90 ℃ temperature, a liquid-solid ratio of 6 mg/L, and 50% sulf uric acid concentration, the iron leaching rate f rom pyrite cinder reaches 98. 62%, with a deviation of only 0. 37% f rom the predicted value. Oxalic acid pref erentially complexes with iron oxides to form soluble [Fe（C2 O4)]+, while sulf uric acid accelerates its conversion to Fe2 （SO4) 3 through protonation. The leaching process is jointly controlled by interfacial chemical reactions and internal dif f usion. Furthermore, ferrous oxalate dihydrate is successf ully recovered f rom the leachate using a photo-induced reduction method, yielding crystals with high purity and intact structure. It provides an economical and environmentally f riendly solution for the resource recovery of metallurgical waste.