Extractive Metallurgy by Brano Fecko-Cegin

6. Calcination in which solid material is heated to drive off either carbon dioxide or chemically combined water. Old type of high furnace used in 1700's. Smelting is a process, which releases the metallic element from its compound as an impure molten metal and separates it from the waste rock part.Smelting is carried out by electrolytic dissociation.

This is where in high temperatures, a liquid metallic chloride compound (as is done with magnesium) or a metallic oxide powder is dissolved in molten electrolyte (as is done with aluminum). Ammonium hydroxide is used for native ores, carbonates, and sulfides, and sodium hydroxide is used for oxides. In each case, electric current is passed through the bath to dissociate the metallic compound; the metal released collects at the cathode, while a gas is given off at the anode. Hydrometallurgy Hydrometallurgy is concerned with the selective leaching of metallic compounds to form a solution from which the metals can be precipitated and recovered. Leaching processes are used when it is the simplest method or when the ore is of too low a grade for more expensive extractive procedures.Because not all ores and concentrates are found naturally in a form that is satisfactory for leaching (removing the soluble constituents from a substance by the action of a percolating liquid), they must often be subjected to preliminary operations. Steel furnace. Back - Home - Next