1 research outputs found
An Emission-Free Vacuum Chlorinating Process for Simultaneous Sulfur Fixation and Lead Recovery from Spent Lead-Acid Batteries
Spent lead-acid battery recycling
by using conventional technologies
is usually accompanied by releases of lead-containing wastewater as
well as emissions of sulfur oxides and lead particulates that may
potentially cause secondary pollution. This study developed a vacuum
chlorinating process for simultaneous sulfur fixation and high-purity
lead chloride (PbCl<sub>2</sub>) recovery from spent lead paste by
using calcium chloride (CaCl<sub>2</sub>) and silicon dioxide (SiO<sub>2</sub>) as reagents. The process train includes pretreatment, simultaneous
PbCl<sub>2</sub> production and sulfur fixation, and PbCl<sub>2</sub> volatilization. The pretreatment eliminated chlorine emission from
direct chlorinating reaction of PbO<sub>2</sub> in the initial S-paste
(PbSO<sub>4</sub>/PbO<sub>2</sub>/PbO/Pb). During the subsequent PbCl<sub>2</sub> production and sulfur fixation step, lead compounds in the
P-paste (PbSO<sub>4</sub>/PbO) was converted to volatile PbCl<sub>2</sub>, and sulfur was simultaneously fixed to the solid residues
in the form of CaSO<sub>4</sub> to eliminate the emission of sulfur
oxides. The final step, PbCl<sub>2</sub> volatilization under vacuum,
is a physical phase-transformation process of ionic crystals, following
a zeroth-order kinetic model. A cost estimate indicates a profit of
USD $ 8.50/kg PbCl<sub>2</sub>. This process offers a novel green
lead recovery alternative for spent lead-acid batteries with environmental
and economic benefits