UMHK was part of a powerful group of global copper producers. Its primary product was copper, but it also produced tin, cobalt, radium, uranium, zinc, cadmium, germanium, manganese, silver, and gold. By the start of World War II, the Société Générale controlled 70% of the Congolese economy. Exercising preponderant influence over the "Comité spécial", the Société Générale effectively controlled the Union Minière from its inception to 1960. Some of the remains of the UMHK form part of the present day company Umicore.