| Abstract Scope |
Harris process for lead softening uses sodium hydroxide and sodium nitrate to remove arsenic, tin, and antimony from molten lead by oxidation. It is known to be better than oxygen softening however the process has a higher cost in terms of reagents used. Sodium hydroxide is corrosive and expensive. In the research, calcium carbonate, calcium hydroxide, and magnesium hydroxide were used as alternative for sodium hydroxide in the softening process. Based on initial results, the research focused on using calcium carbonate for subsequent softening process. In this research, activity coefficients of the impurities: arsenic, tin and antimony were calculated and compared with that obtained with sodium hydroxide in the melt. Softening experiments were conducted on lead bullion by design of experiment method by varying temperature, time, and reagent quantity. Dross obtained was quenched and analyzed chemically and with XRD to identify the phases formed. Experimental and theoretical results are presented. |