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Raw Lead Extraction
Workers use heavy machinery to dig rocks or detonate them with dynamite, and then load them to trucks.
Removing Waste Rock
After raw lead is extracted from the mine, it is sent to a processing mill, where the waste rock is removed. First, the raw lead is crushed into very small pieces, then grounded in a mill.
Also read: Properties and Uses of Lead
Flotation
The crushed ore is diluted with water and poured into a tank called the flotation tank. The flotation process collects the sulfur-containing parts of the ore, where the sulfide particles form a kind of oily butter on top. At the end of this process, the lead is separated from the rock, and other metals such as zinc and copper.
Filtering
After the flotation process, raw lead is sent to a filter, which in turn removes up to 90% of the water. Raw lead at this stage contains between 40% and 80% of lead, with large amounts of other impurities, mostly sulfur and zinc. At the end of this stage, lead will be ready to be shipped to the smelter.
Also read: Properties and Uses of Cobalt
Heating
Heated air (2550° F) flows into the ore and coke is added as fuel. After heating the ore in this way, it is combined with a fragile substance called sinter. Sinter contains mostly lead oxide, but it may also contain zinc oxides, iron, silicon, lime and sulfur.
Melting
Air flows through the bottom of the oven where coke is burned. Burning coke generates a temperature of about 2,200° F and produces carbon monoxide. Carbon monoxide interacts with lead and other metal oxides and produces molten lead.
Also read: Learn More About Palladium
Purification
The purity of the molten lead ranges between 95% to 99%, and it needs to be further purified to remove unwanted impurities, because the percentage of commercial lead purity should be between 99% to 99.99%.
Casting
When lead is refined enough, it is cooled and poured into blocks that may weigh about a ton, and this is the final product.
