Chemical characterization and local dispersion of slag generated by a lead recovery plant in Central Mexico

Abstract

A toxic waste “slag” generated in a lead (Pb) recovery plant was characterized and its local “slag” dispersion was monitored. The major constituents of the “slag”, in increasing weight percent, were CaO (1.5), PbO (3.4), SiO₂ (5.2), Na₂O (17.8), SO₃ (27.5) and Fe₂O₃ (40.7). The “slag” was alkaline with a pH of 10 and an electrical conductivity of 606 dS m^-1. Tests for Pb leaching indicated that, in a moderately acid environment, as much as 8 mg Pb L^-1 may be washed out of the “slag”; there are amounts that are well above the limits set by Mexican legislation. The highest concentration of Pb in soil surrounding the recycling plant (447 mg Pb kg^-1) was found 50 m southwest of the recovery plant. Due to its high Pb level and easy dispersion into the environment, the health of human settlements in the area could be at risk.

Keywords: Toxic waste, alkaline material, Pb leaching

African Journal of Biotechnology, Vol 13(19), 1973-1978