EXTRACTION OF METALS FROM SULPHIDE ORES BY WET METHODS

Abstract

Not until the middle of the nineteenth century, when a substantial body of inorganic chemistry had begun to accumulate, were metals produced in any volume by methods involving dissolution of ores and precipitation of metals from the solutions. Copper sulphate and ferrous sulphate had been produced by atmospheric oxidation or “weathering” about the fifteenth or sixteenth century, but except for occasional “cementation” of copper from the sulphate solution by the addition of metallic iron, it is doubtful whether this procedure was seriously considered as a method of extracting copper metal from ore. By mid-century the rapidly expanding concepts of the atom, of electrical energy, and of the reactions of metal salts in aqueous solution began to point the way to entirely new methods of producing metals by leaching metal compounds in suitable solvents, separating impurities by chemical treatment of the solution, and finally precipitating metals from solution by electrolysis or “cementation” with a more reactive metal. Within a very few years the knowledge of inorganic chemistry had advanced to the extent that procedures employing aqueous solutions were technically available for producing a large number of the then-known metals, even though commercial application was not feasible by reason of high cost or limited engineering technology.