Lead Materials – Ore Extraction
Extracting Lead Materials from Ore
Lead is a dense, soft, low-melting metal. Lead is the densest common metal except for gold, and this quality makes it effective in sound barriers and as a shield against X-rays. Lead resists corrosion by water, so it makes a long-lasting roofing material.
Only about half of the lead materials used today are produced from mining, the rest is obtained from recycling, mostly from car batteries. The largest producer of lead materials in the world is Australia followed by the USA, China and Canada.
Lead is extracted from ores dug from under-ground mines. Of the more than 60 minerals that contain lead, only 3 galena, cerussite and anglesite are commercially viable. Usually, lead is found in conjuction with other metals such as silver and zinc. Lead materials are mined as a by product of these other more valuable metals.
Extracting the lead materials from the ore is a multi-step process. First the lead ore is ground into small particles that are less than 0.1mm, giving the ore a texture similar to table salt. Next the lead powder is put through a flotation process, that involves mixing the lead ore with water, the addition of pine oil and the introduction of air bubbles and agitation which forms an oil froth, containing the lead ore, on the surface.
The froth is skimmed and then filtered to remove the water. The powder is then sintered at over 2500oF to oxidize impuritites such as sulphur. The resulting powder is further heated in a blast furnace, with carbon producing molten lead which is drawn off into lead molds.
At this stage the lead is about 95% pure and is further refined to reach greater than 99% purity by melting and skimming impurities. Gold and silver can be removed from the bullion by adding to it a small quantity of zinc. The gold and silver dissolves more easily in zinc than in lead, and when the bullion is cooled slightly, a zinc dross rises to the top, bringing the other metals with it.
Once the lead materials reaches a sufficient level of purity it is cast into lead blocks as the finished product. In some cases small quantities of impurities, such as Copper, Antimony, Tin & Zinc, may be added to form lead alloys with various properties.
Nuclead can cast lead alloy pours or lead products for all your needs. Nuclead also has available an extensive in-stock inventory of lead, please click for more details.
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