Comprehensive recovery of arsenic and antimony from arsenic-rich copper smelter dust.

In view of reducing contaminant and recovery arsenic and antimony, a novel technology was proposed to recover arsenic and antimony from arsenic-rich copper smelter dust comprehensively. The technique route includes three stages: arsenic and antimony trioxides were leached from the copper smelter dust with hydrochloric acid; trivalent arsenic ions (As3+) were then reduced to less toxic simple arsenic (As) by sodium hypophosphate (NaH2PO2) and recovered; and stepwise recovery of antimony by SbCl3 was achieved by the continuous distillation technique. The results indicates that the leaching efficiency of As and Sb was over 97.5% and 96.8% under conditions of initial 4.0 mol/L HCl, liquid-solid ratio (L/S) of 6:1, leaching temperature of 363 K and time of 2 h. Over 92.5% arsenic was recovered by NaH2PO2 reduction under the suitable conditions: 363 K, 1.5 h and 2.0 times addition of NaH2PO2. The recovery rate of Sb is more than 97.53% at 393 K. The distillation temperature of SbCl3 was optimized between 463 K and 473 K. The corresponding mechanisms of the leaching and recovering of arsenic and antimony were systematically investigated and confirmed by E-pH diagram, thermodynamic calculation, arsenic speciation, composition analysis and XRD characterization.