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What is gangue and how is it removed from lead ore?
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lead processing
A zinc-lead blast furnace and lead-splash condenser. This technology is utilized mainly for producing zinc while managing both lead and zinc from raw materials, a technique that was highly influential in 20th-century smelting.
Gangue refers to the unwanted or valueless rocks and minerals that are naturally mixed with valuable ore deposits. Because ore and gangue are typically mined together, they must be separated through mineral processing to isolate the desired metallic elements.1
In the context of lead processing, the removal of gangue occurs at concentrating mills after the ore has been finely crushed. The most common method for lead sulfide ores is flotation separation. In this process:23
- The crushed ore is mixed with water and specific chemicals (such as pine oil) in a tank.2
- Air is bubbled through the mixture, causing the metallic particles to attach to air bubbles and float to the surface as an oily froth.23
- The mostly valueless gangue, which does not attach to the bubbles, sinks to the bottom of the tank and is removed.23
Other methods, such as gravity separation, may also be used depending on the density differences between the minerals. Once the gangue is removed, the resulting lead concentrate is sent for further smelting and refining.452