HYDROMETALLURGICAL PROCESS INNOVATION

Hydrometallurgy consists of a series of separations that begins with leaching of ores or concentrates and ends with fairly pure, marketable cathodes, powders, or compounds recovered from solution. Intermediate separations are conducted to recover by-products, isolate impurities, or enhance the productivity of subsequent unit operations. There is a constant search for new technologies that will: (1) increase the productivity of parts of the process; (2) reduce operating costs; (3) reduce adverse environmental impact of effluents from the process; and (4) (in the case of the need for new plant capacity) develop new, simpler, cleaner, more economic processes. Innovations in hydrometallurgy have historically taken the form of: (1) testing new reagents for leaching; (2) accelerating the rates of leaching and improving the final extractions; (3) offering new options in solvent extraction or ion exchange; (4) incremental improvements in electrowinning and refining; (5) improved methods of making liquid-solid separations that involve better washing and lower water usage; and (6) developing entirely new processes for specific industries (i.e., lead, copper, or refractory gold) that substitute hydrometallurgy for either mineral processing or for pyrometallurgy. Process innovations in hydrometallurgy, both successful and unsuccessful, are reviewed, and the possibility of developing a strategy for evaluating innovations for their chance of success is discussed. From such a review, it becomes evident that true, novel, successful inventions are the product of a serendipitous, unpredictable, creative process. However, some strategies are revisited that have failed previously, on the basis that their reason for failure may now be obsolete.