Lead recovery from a lead concentrate throughout direct smelting reduction process with mixtures of na₂co₃ and sic to 1000^◦c

Lead was recovered through a direct smelting reduction route from a lead concentrate by using mixtures of Na₂CO₃ and SiC to 1000^◦C. The lead concentrate was obtained from the mining State of Zacatecas, México by traditional mineral processing and froth flotation. The experimental trials showed that 86 wt.% of lead with a purity up to 97% can be recovered from the lead concentrate by a single step reduction process when 40 wt.% Na₂CO₃ and 0.4 g SiC were used in the initial charge. The process was modeled in the thermodynamic software FactSage 7.3 to evaluate the effect of adding different amounts of Na₂CO₃ on the lead recovery rates while holding constant the SiC amount and temperature. The stability phase diagram obtained showed that an addition of 34 wt.% Na₂CO₃ was enough to reach the highest lead recovery. It was observed that the interaction of Na₂CO₃ and SiC at a high temperature promotes the formation of C and Na₂O, and SiO₂, respectively, where the Na₂O partially bonds with silica and sulfur forming Na₂S and sodium silicates which may decrease the SO₂ emissions and increase the weather degradation of the slag. The PbS was mainly reduced by the produced C and CO formed by the interaction between Na₂CO₃ and SiC at 1000^◦C. The predicted results reasonably match with those obtained experimentally in the lead recovery rates and compounds formation.