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Modified Pyro-metallurgical Technology for Recovery of Impurities from Crude Lead Using Chalk Powder

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Author(s): Fakhri Hamdullah Ibraheem Al-nidai

Journal: International Journal of Engineering Trends and Technology
ISSN 2231-5381

Volume: 4;
Issue: 7;
Start page: 2957;
Date: 2013;
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Keywords: Lead | antimony | chalk powder | Harris process | sodium nitrate

ABSTRACT
Harris process is a well-known technology for purification of lead from alloying elements antimony, tin and arsenic (impurities). The process used sodium nitrate as oxidizing agent with sodium hydroxide for agglomeration of the floated skim over molten lead followed by bubbling of air which is done under controlled temperature and efficient mixing. Sodium nitrate composition contains easy liberated oxygen for continuously oxidizing (burning) of impurities; it is limited available material for its secure situation. The scope of the research is to find a material which can substitute sodium nitrate and be feasible, safe and has no environmental impact. It is found from the research that fine powder of Calcium Carbonate grain (chalk powder) take a role as oxidizing agent without air bubbling. It is shown that the oxidations reactions occurs on the surface of calcium carbonate granules, a yellow–brown skims floating over molten surface from impurities and lead oxidant, whenever a fine grain used, a higher efficiency get. The new technology has many advantages but it has also a disadvantages represented by increasing process technology time by 15% and increasing the amount of solid skimmed waste by 10% which can be later recycled again to the rotary furnace for reduction and get high antimony lead which is preferable for production of electrode grid for lead acid battery.

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