Initially, the UMHK concentrated on mining the state's extensive copper deposits, before diversifying into cobalt, tin, uranium (in which it at one point held a near-monopoly in global supply) and other precious metals.

[11] The firm suddenly found itself without the vast majority of its business (despite later receiving financial compensation for the physical assets seized by Mobutu's regime)[12] but managed to survive: full ownership passed to conglomerate Société Générale de Belgique, where it was grouped with its other metals and mining interests.

[13] The much enlarged company was initially renamed Acec-Union Minière[13] (although the prefix was dropped in 1992)[14] and subsequently set about streamlining its organisational structure, but the global economic downturn of the early-to-mid-1990s hit profits[9] and forced management to implement a major restructuring programme in 1995.

[15] The three-year plan, implemented under the guidance of recently appointed CEO Karel Vinck,[16] involved the loss of around 25% of Union Minière's workforce[17] and the sale of a number of non-core assets, including a zinc wire operation,[17] French roofing material retailer Asturienne[17] and much of the company's exposure to the diamond products sector (including Diamant Boart [nl]).

[29] Other sources of materials used for recycling include slag, spent fuel cells, automotive and industrial catalysts and scrap electronic equipment.

[31] The Recycling segment, based in Hanau, Germany, also encompasses a management unit, which sells precious metals in ingot form to industrial clients and offers access to related financial instruments for hedging purposes.

Umicore increased its presence in the sector with the June 2007 purchase of the catalyst division of troubled American auto parts manufacturer Delphi for $55.6 million.

[35] Furthermore, Umicore went on to acquire Haldor Topsøe’s heavy-duty diesel and stationary catalyst businesses in 2017 [36] Performance Materials concentrates on the production of specialised items, chiefly from precious metals and zinc.