Production of lead via ammoniacal ammonium sulfate leaching

Laboratory-scale investigations of a novel hydrometallurgical process for lead production are described. The process is based upon the solubility of certain oxidized lead compounds in aqueous ammoniacal ammonium sulfate (AAS) solutions. There are, essentially, five steps in the process, viz: pretreatment to convert lead in the raw material to a suitable oxidized form; dissolution of the lead compounds in an AAS solution at ambient temperatures and pressures; recovery of the lead from solution by electrolysis or precipitation; conversion of the products of the preceding stage to saleable products; treatment of solutions to make them suitable for recycling. This new process avoids many of the difficulties of existing hydrometallurgical processes for lead.