A Little Bit of History

Solvent extraction has been long practiced for analytical chemistry applications. Purification of uranium leach solutions was the first major application of solvent extraction in hydrometallurgy. Prior to the late 1960’s hydrometallurgical
copper was very limited in scope. Leach solutions were passed over scrap iron to precipitate copper metal:

\[\ce{Cu^2+_{(aq)} + Fe_{(s)} = Cu_{(s)} + Fe^2+_{(aq)}} \tag{1}\]

This worked because Cu⁺² can easily oxidize iron. But, scarp iron is fairly costly, copper metal recovery was somewhat awkward and the copper was quite impure, requiring further refining. In 1968 Ranchers Exploration and Development Corp. started the first copper SX plant in Miami, Arizona^[1]. This soon supplanted the old cementation technology (as represented by the reaction above). Copper SX-EW became the modern standard by which hydrometallurgical copper was produced, and greatly expanded the potential for the business.