Lead processing and smelting plants work with both primary and secondary lead. Primary lead is mined, separated from ore, and refined into various products, whereas secondary lead is recovered from used objects, such as used lead-acid batteries, for reuse in other products. Smelting is a key process in lead product production, and involves heating lead ore or recovered lead with chemical reducing agents.
Both primary and secondary smelting processes can be responsible for releasing large amounts of lead contamination into the surrounding environment.
The primary smelting process involves separating lead from ore using heat and reducing or purifying agents such as coke and charcoal. When lead ore is mined, it must undergo several different processes in order to be turned into usable or metallurgical lead material. Lead dust and smoke can be released during all of these processes, and slag contaminated with lead particles may be left over after smelting.
Secondary smelting of lead is similar to primary smelting, but does not require the initial sintering process. Once lead is recovered from used materials, it is placed into a furnace where it is heated with coke or charcoal in order to isolate the lead from other compounds.
Like primary lead smelting, the processing of secondary lead can also produce lead dust and toxic slag. If smelting plants and equipment are not properly constructed to minimize the release of pollutants, lead toxins can often enter the surrounding environment and contaminate soil, water, and food.