Abstract
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.
Highlights
Published: 28 December 2021As a result of its widespread use in metallurgy and the chemical industry, as well as in radiation protection, lead is an important non-ferrous metal with broad applications in batteries, machinery manufacturing, and medicine
Lead was recovered through a direct smelting reduction route from a lead concentrate by using mixtures of Na2 CO3 and SiC to 1000 ◦ C
A high recovery of crude lead (86 wt.%) with a purity up to 97% was obtained in a single-step process by using a mixture of 40 wt.% Na2 CO3 and 0.4 g SiC to 1000 ◦ C; The C consumption to produce 1g bullion lead was between 0.20 and 0.24 g
Summary
As a result of its widespread use in metallurgy and the chemical industry, as well as in radiation protection, lead is an important non-ferrous metal with broad applications in batteries, machinery manufacturing, and medicine. Both primary lead ores galenarich (PbS) and secondary resources—mainly waste lead-acid batteries—are used as raw materials for lead production [1]. The smelting process includes the sinter plant–blast furnace route and direct smelting reduction, including oxidation, reduction, and refining. In the sinter plant–blast furnace route, PbS is oxidized in the solid state to remove sulfur, and PbO is produced at the same time. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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