Various semi-finished products, containing PbSO4, can be processed in lead production. PbSO4 dissociation is investigated in order to estimate the effect of temperature, time and presence of various solid fuels as reducing agents on the degree and mechanism of dissociation. It is shown that the presence of coal considerably decreases the dissociation temperature and increases the degree of PbSO4 dissociation. A mechanism of the studied process is proposed. The results obtained, and their industrial applicability, are confirmed by thermal-treatment study of lead cake and coal mixtures and a modeling of the agglomeration process.