Management Mines and Metallurgy Mines and Metallurgy Engineering Engineering Aviation Food Industry Community Services Energy
Home > Activities > Metallurgy & Mines > STL

Société pour le Traitement du Terril de Lubumbashi (STL)

Image 01


SOCIÉTÉ POUR LE TRAITEMENT DU TERRIL DE LUBUMBASHI (STL) is an S.P.R.L. (private limited liability company) under Congolese law. STL treats part of the Lubumbashi slag hill using pyrometallurgical processes.

STL obtains the scoria from the Lubumbashi Slag from the trading company GTL, which in turn acquired it from Gécamines SARL, the owner of the slag.
STL manages and runs the daily metallurgical processes, as well as all of the technical questions related with it.

When it was inaugurated by STL in November 2000, the electric furnace with a diameter of 17 metres and a maximum capacity of 36 megawatts was the largest in the world. To this day, it remains the second largest furnace in the world for its type of metallurgy.

The metallurgical process employed by STL is a pyrometallurgical process that consists in the carbothermic reduction of metallic oxides contained in the scoria.

The annual production capacity of STL is around 5,500 tonnes of cobalt and 3,500 tonnes of copper. Apart from its production of white alloys in the form of granules, through the complete treatment of the gas from its electric furnace, STL also produces over 22,000 tonnes of zinc oxide per year in the form of granules and/or powder.

In line with the treatment of these gases, the sparing use of water, the majority in closed circuit, makes STL a clean company, adhering to rigorous environmental standards, comparable to those in force in Europe.

© Jean-Dominique Burton
Using state-of-the-art technology, STL uses pyrometallurgy to exploit the Lubumbashi’s slag hill,originating from a previous pyrometallurgy activity by the Union Minière and the Gécamines.

© Jean-Dominique Burton
Lubumbashi’s slag hill


As a whole, the industrial activity of STL combines audacity and state-of-the-art technology in the surveillance and monitoring of the operations. This has since been exported and adopted by other companies throughout the world.

Apart from its industrial activities, STL engages in activities to benefit the urban community of Lubumbashi. Notably, the company supports associations and sporting events, as well as initiatives in the field of education and training. Besides, STL supports the FONDATION RACHEL FORREST.

  STL'S economic impact 
The Lubumbashi Slag Hill

Route de Kipushi 4
B.P. 1531, Lubumbashi
République Démocratique du Congo
Tél. +243.970.32.815 | Fax. +
Sites web: |

Fondation Rachel Forrest

Image 01

Organization chart

Image 01


Image 01


Image 01