Secondary Smelting Methods

Secondary lead smelting is predominantly based on the treatment of scrap lead-acid batteries, as detailed in Chapter 10. A wide range of smelting methods are used for the treatment of secondary lead, originally based on traditional smelting methods such as the hearth and blast furnace, feeding whole batteries, but are changing under stricter environmental controls to the use of prior separation and specialised reduction in rotary furnaces or newer electrochemical techniques. 

Processes are essentially classified by the type of equipment used, as follows  

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The flotation process was developed in Australia at the turn of the century to treat the primary sulfidic silver/lead/zinc ore at Broken Hill, New South Wales, following the mining of the overlying secondary ore. Oxidation to form the secondary zone had resulted in a concentration of silver and lead, and this section of the ore body could be smelted directly. The underlying sulfide zone, which comprised the bulk of the resource, was less amenable to treatment in the smelters of that era, and a method was required to recover the zinc values if the potentiality of the primary ore was to be realized. Many approaches were pursued to solve the sulfide problem before selective flotation was developed. The flotation process was then rapidly adopted by mining companies throughout the world. 

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