The role pH plays in the precipitation of lead sulphate from an alkaline waste solution

Abstract

A local manufacturer of lead chemicals has expressed a definite interest in buying recovered lead sulphate from S.A Precious Metals, a minerals processing company. The recycling of lead provides a means of reducing the strain on resources that is caused by the use of virgin materials such as lead. In addition, recycling prevents any damage caused by improper treatment processes and disposal practices that would otherwise lead to groundwater contamination. Research into lead precipitation has so far focused mainly on acid waste, perhaps because of the size and influence of the lead acid battery industry. The work described in this dissertation was motivated by the efforts of S.A Precious Metals to process the company’s lead-­‐alkaline waste. Initially, the scientists carrying out laboratory-­‐scale tests encountered solids-­‐handling problems. The writer undertook the investigation reported in this document to find a viable means of recovering both lead sulphate and sodium sulphate from solution. During the batch trials, the researcher recovered lead sulphate via precipitation from the lead-­‐containing solution, while precipitating the sodium plumbate solution (normally considered hazardous waste) with sulphuric acid. This process offers a low-­‐cost answer to the problem that also offers a quick turn-­‐around, saleable by-­products and a benign waste stream.