Study on SART process for treating carbon-in-leach barren solution from flotation tailings of a sulfide mine

The carbon-in-leach (CIL) barren solution generated by cyanidation is difficult to treat, and its direct discharge or reuse intensifies environmental and operational pressures. In this study, process optimization of the SART (Sulfidation-Acidification-Regeneration-Precipitation) method and reuse tests of the treated effluent were carried out on the CIL barren solution from the flotation tailings of a sulfide ore, and the effects of key parameters, acid source substitution, and water recycling on treatment performance were systematically analyzed. The results showed that the optimal conditions were sulfidation followed by acidification, with a mass ratio of Na₂S to total copper of 0.80-1.00, an acidification pH of 4.50-6.50, a PAM dosage (mass concentration) of 5 mg/L, and a sedimentation time of 20-120 min. Under the optimized conditions, the SART process achieved a total copper removal rate of 93.96%; the average mass concentration of total copper in the treated effluent was 9.47 mg/L, and the mass concentration ratio of complex cyanide to total cyanide decreased to 4.50%, indicating sound cyanide recovery. The sulfide precipitate had a copper grade as high as 65.66% and an arsenic mass fraction of 0.09%, while the gold entrainment rate was merely 0.31%. When the treated effluent was reused in cyanide leaching, the average leaching rates of gold and copper remained stable, and the sodium cyanide consumption per ton of ore decreased by 63.00%. This technology achieved valuable metal recovery, wastewater recycling, and reagent consumption reduction, reduced the environmental risk of the tailings storage facility, and provided a reference for the comprehensive treatment of similar CIL barren solutions.