Refining of lead

The crude lead bullion produced by primary and secondary smelting of lead 

Property Roasting Reverberatory furnace Copper convertor 

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Trade association of manufacturers of lead products and lead components mining companies, smelters and refiners of lead. Provides lead information to consumer s and is a clearinghouse for lead recycling information. 

In contrast to the fire refining of copper, where the oxidation stage needs to be followed by a deoxidation step, no deoxidation step is necessary in the fire refining of lead. This is because the solubility of oxygen in liquid lead at typical refining temperatures is quite low (2 10 2 to ltT1 at-% at 600 to 700 °C). 

The problem of the separation of zinc and lead from each other is encountered not only in the refining of zinc but also in the refining of lead. When lead is subjected to refining by the Parkes process, a certain amount of zinc, which is not insignificant, is introduced into the refined lead bullion. This zinc impurity may be removed by distillation. 

Cadmium, as cadmium oxide, is obtained mainly as a by-product during the processing of zinc-bearing ores and also from the refining of lead and copper from sulfide ores (USPHS 1993). In 1989, the United States produced 1.4 million kg of cadmium (usually 0.6 to 1.8 million kg) and imported an additional 2.7 million kg (usually 1.8 to 3.2 million kg). Cadmium is used mainly for the production of nickel-cadmium batteries (35%), in metal plating (30%), and for the manufacture of pigments (15%), plastics and synthetics (10%), and alloys and miscellaneous uses (10%) (USPHS 1993). 

Electrolytic refining of lead bullion is commonly employed in many modern plants to obtain high purity grade metal. Various separation processes for removal of individual metals are not required. In such refining (Betts process), a solution of lead fluosilicate is used as an electrolyte, while the anode consists of impure lead bullion and the cathode constitutes a thin sheet of pure lead. Lead deposits on to the cathode during electrolysis. Impurity metals remain undissolved and attached to the anode, forming a slime which may be removed after electrolysis and treated for recovery of these metals. 

Thallium Smelting and refining of lead and zinc, pesticides... 

Fig. 3 Process flow diagram for the concentration, extraction, and refining of lead...

R.P. Knight and R.J. Reader, The Refining of Lead Bullion and Precious Metals Recovery at Britannia Refined Metals Ltd. , Lead into the Future. IMM, London, England, 1996,53-73. 

Mining, smelting and refining of lead, as well as the production and use of lead-based products give rise to release of lead into the environment. This takes the form primarily of either lead-rich aqueous effluent streams, or emission of fume and dust into the air. A large part of the lead discharged into surface waters is rapidly incorporated into suspended and bottom sediments, and most of this lead wiU ultimately be found in marine sediments. Of greater concern, however, is the emission of lead into the atmosphere. The finer aerosol particles... 

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