Bullion, lead

Betterton-KroIIProcess. MetaHic calcium and magnesium are added to the lead bullion in a melt and form ternary compounds that melt higher than lead and are lower in density. By cooling the lead bath to a temperature close to the melting point of lead, the intermetalHc compounds high in bismuth content soHdify and float to the top where they are removed by skimming. 

Betts Electrolytic Process. The Betts process starts with lead bullion, which may carry tin, silver, gold, bismuth, copper, antimony, arsenic, selenium, teUurium, and other impurities, but should contain at least 90% lead (6,7). If more than 0.01% tin is present, it is usually removed from the bullion first by means of a tin-drossing operation (see Tin AND TIN ALLOYS, detinning). The lead bullion is cast as plates or anodes, and numerous anodes are set in parallel in each electrolytic ceU. Between the anodes, thin sheets of pure lead are hung from conductor bars to form the cathodes. Several ceUs are connected in series. 

The lead bullion is refined using pyrometallurgical methods to remove any... 

Prior to smelting, batteries are usually broken up and sorted into their constituent products. Fractions of cleaned plastic (such as polypropylene) case are recycled into battery cases or other products. The dilute sulfuric acid is either neutralized for disposal or recycled to the local acid market. One of the three main smelting processes is then used to reduce the lead fractions and produce lead bullion. 

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. 

The dross is removed and fed into a dross furnace for recovery of the nonlead mineral values. To enhance copper recovery, dressed lead bullion is treated by adding sulfur-bearing materials, zinc, and/or aluminum, lowering the copper content to approximately 0.01%. 

Lead dressing Lead bullion, soda ash, Slag containing such... 

Lead arsenates, 74 797 Lead azide, 70 727-729 74 792 Lead babbitt, 3 52, 52t arsenic addition to, 3 271 Lead-base babbitts, 24 797 Lead-based paint, 74 765 Lead-based paint remediation, 18 75 Lead-based pigments, 79 386. See also Lead chromate pigments Lead benzoate, 74 794 Lead bisilicate, 74 796 Lead blast furnace, 74 737 Lead borate, 74 797 Lead bromide, 74 785 Lead bullion, 74 742, 745... 

Lead oxide, silicate, and the gangue material consisting of silica, lime, iron oxide, zinc oxide and alumina, react in a blast furnace at 1,000°C, producing lead (lead bullion) along with matte and speiss that result from reactions of residual sulfur with copper and arsenic. Slag, dust, and gases (CO and CO2) are the other products generated in the blast furnace. The principal reactions in the furnace are ... 

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. 

These and undoubtedly several other reactions occur during the smelting of the very complex charge placed in the furnace. As indicated by the preceding reactions, elemental lead may be liberated as a product of five (or more) separate reactions. The lead so produced is drained from the furnace and is then ready for purification. The chief impurities present in the crude product (known as lead bullion) are Cu, Ag, Au, As, Sb, and Bi. 

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