Research Article
Vasant Kumar R, Jiakuan Yang a
Abstract
Lead in spent batteries is in the form of lead sulphate (PbSO4) along with lead oxides and a small proportion of metallic lead. It is recovered as lead by using energy intensive decomposition and reduction process. Dried powder from the spent lead paste and lead-alloy grid from used battery is charged in smelters either in stand alone reactors or more often with lead concentrates derived from lead sulphide ores. Decomposition of PbSO4 requires the use of relatively high temperature (typically >1000°C) using fossil fuel as the source of energy. The smelting route is associated with CO2 greenhouse gas emission, pollutants emission of lead fumes and SO2 and energy consumption of several KWh per Kg of lead thus treated. A new process of recovering lead directly from spent battery paste as PbO precursor for making new paste has been developed. In this new environmentally sound, paste to paste process, the net-carbon, SO2 and lead dust emissions are very low towards making new batteries without the use of high temperature pyrometallurgy or the energy-intensive electrowinning processes. By reacting spent lead battery paste with organic reagents and then combusting the organic crystallites, high surface area PbO is directly available for making pastes for new batteries. In this paper the importance of the chemical reactions between the lead compounds and the organic carboxylic acids are discussed.