The interaction between molten Na2CO3-Na Cl salt and Sb and the solubility of Sb in molten salt were investigated in the temperature range of 700-1000 °C.The results show that the dissolution equilibrium of Sb in molten salt can be achieved in 3 h,and the amount of Sb dissolved in the melt decreases as the viscosity decreases.The solubility limits in an eutectic mixture were determined as 5.42%,2.42%,0.75% and 0.68% at 700,800,900 and 1000 °C,respectively.A high temperature and appropriate content of Na Cl will decrease the dissolution of Sb.The insoluble Sb was collected at the bottom of molten salt.The Sb dissolved on the surface of the molten salt is easily oxidized,whereas the Sb dissolved inside the molten salt is randomly distributed in terms of the form of metal Sb.
Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.
