Recovery of Lead in Lead Zirconate Titanate Ceramics by Wet Ball Mill with Acidic Solution

Abstract

The possibility of preferential recovery of lead from lead zirconate titanate (PZT) ceramics by wet ball milling with aqueous H₂SO₄ solution was investigated. The wet ball milling was performed using a pot mill apparatus in air for 0-96h at room temperature with the rotational speed fixed at 300rpm. Untreated PZT was dipped in aqueous H₂SO₄ solution for comparison with the wet-ball-milled specimen. The diffraction lines of the PZT crystallites disappeared completely from the XRD results, and only the diffraction lines of PbSO₄ were confirmed by the wet ball milling for more than 48h. For all the dipped specimens, the diffraction lines of PZT were identified even when the specimens were treated in 4.5mol/dm³ H₂SO₄ solution for 96h. According to ICP analysis of the dissolved components into the H₂SO₄ filtrate, the amounts of zirconium and titanium dissolved in the solution were found to increase with increasing treatment time, and the leaching behavior of both ions conformed closely to the collapsing behavior of the PZT crystal structure. As for lead ion in the solution, the dissolution amount was below 0.1% compared with the initial lead content in PZT ceramics under all the ball milling conditions. These results indicated that more than 99.9mass% of lead in PZT can be recovered as PbSO₄ by wet ball milling for more than 48h. The purity of the recovered PbSO₄ calculated from the ICP results was approximately 98mass%.