Over the course of Dr. Robertson’s career, the ferrous and non-ferrous industries have seen enormous changes, essentially amounting to a “technological revolution”. In iron and steel, the “mega” blast furnace of some 6,000 m3 working volume is now standard. Similar huge changes in process technology and plant size have occurred in the non-ferrous industry. As an example, the large fuel-fired reverberatory furnace, once the mainstay of the copper industry, has disappeared - replaced by new flash and bath smelting technologies. The energy consumption per unit mass of metal produced has also been reduced considerably. Our understanding of the thermodynamics and mechanisms of metallurgical reactions, a field to which Dr. Robertson has significantly contributed, has made great strides. This paper reviews all these changes with particular reference to the copper smelting industry. The paper also provides some comments on future trends.