The Compagnie minière de l'Ogooué, or COMILOG, is a manganese mining and processing company based in Moanda, Gabon.

The company is the world's second largest producer of manganese ore. At first the ore was carried by a cableway to the border with the Republic of the Congo, then by rail to the sea at Pointe-Noire.

[1] In 1951 a joint mission of the Bureau Minier de la France d'Outre-Mer and U.S. Steel found a large deposit estimated at over 100 million tonnes of marketable ore.[2] The ore is high quality with a manganese content of 45–50%.

Above this is the main ore zone, a 3 to 9 metres (9.8 to 29.5 ft) layer of plates of similar minerals between bands of clay, silica and iron bearing material.

Above the main ore zone is a 5 to 6 metres (16 to 20 ft) layer rich in alumina and iron-rich manganiferous pisolites, with a manganese content of 15%.

[4] COMILOG was established on 24 April 1953 to mine a deposit estimated at 50 million tons of manganese ore in Gabon, with US Steel owning almost half the company.

The solution was to carry the ore by cableway from Moanda to Mbinda in the Republic of the Congo, and then by a new railway line via Makabana to Monto Bello.

[2] Henri Lafond, the first president of COMILOG, was responsible for equipping the mine and for building the cableway, railway and facilities for ore handling at Pointe-Noire.

It connected the new port being built at Owendo to Franceville on the upper Ogooué River and opened up the forests and mines of the interior.

[9] In 1985 six MaK G 1203 BB locomotives with Cummins engines were built by Maschinenbau Kiel for the OCTRA (Office du chemin de fer transgabonais) railway company.

[16] At Owendo COMILOG operates a private ore shipment terminal and storage facilities with capacity for three months' production.

[18] After ore shipments stopped the Republic of the Congo expropriated the track and equipment in their country, worth about 60 billion CFA francs.

[11] The COMILOG railway in the DRC was taken over by the CFCO (Chemin de fer Congo-Océan) and is the main means of transport for people and goods north of Niari.

[20] The Complex Industriel de Moanda (CIM) was inaugurated on 30 December 2000 by Omar Bongo, President of Gabon.

[21] In 2009 work began on building the Complexe Métallurgique de Moanda (CMM), which would produce silico-manganese[a] and manganese metal.

[9] On 12 June 2015 Ali Bongo Ondimba, President of Gabon, officially inaugurated the CMM, the first manganese processing factory in the country.

As of 2005 most of the sinter produced by COMILOG was shipped to a smelter in France operated by the Eramet subsidiary, SFPO (Société du Ferromanganèse de Paris-Outreau).

[26] Production fell to 3 million tonnes in 2012 due to weak demand in China and Europe, the main markets.

[10] The NickelSLN Metallurgical Company was formed in 1974, with equal shares held by Elf Aquitaine and Imétal (formerly Société Le Nickel).

[32] As of 2012 COMILOG employed 3,200 people in Gabon, including 1,700 at the Société d’exploitation du Transgabonais (SETRAG), the subsidiary that operates the railway.