sentences:  Katanga Mining Limited, a Swiss-owned company, owns the Luilu Metallurgical Plant, which has a capacity of 175,000 tonnes of copper and 8,000 tonnes of cobalt per year, making it the largest cobalt refinery in the world.After a major rehabilitation program, the company resumed copper production operations in December 2007 and cobalt production in May 2008.In April 2013, anti-corruption NGOs revealed that Congolese tax authorities had failed to account for $88 million from the mining sector, despite booming production and positive industrial performance.