Lead recovery from PbZrO_3 using wet ball-mill technique and hydrothermal synthesis of α-zirconium phosphate from wastewater for resource recovery

摘要

Lead recovery from lead zirconate (PbZrO_3) ceramics was investigated using a wet ball-mill treatment in H_2SO_4 aqueous solution. Subsequently crystalline α-zirconium phosphate (α-Zr(HPO_4)_2·H_2O) was synthesized using a hydrothermal technique in order for the resource recovery of zirconium in the wastewater after the wet ball-mill treatment. A wet ball-mill treatment in 4.5 M H_2SO_4 aqueous solution for 24 h was capable of converting more than 99.9% of the Pb initially included in the PbZrO_3 to solid state PbSO_4 with a purity of 98%. On the other hand, the Zr in the PbZrO_3 was dissolved into the acidic solution during the treatment. The Pb and Zr metal elements coexisting in PbZrO_3 were successfully separated by the wet ball-mill technique. Then, resource recovery of zirconium in the wastewater was examined. Crystalline α-Zr(HPO_4)_2·H_2O was synthesized by hydrothermal treatments in 3.1-12.5 M H_3PO_4 aqueous solutions at temperatures of 120-240 ℃ for a duration of 70h. The hydrothermally prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and then they were also evaluated in terms of cation exchange capacity (CEC) measurement and thermogravimetric (TG) analysis.