LUNSAR - London Mining will spend $300 million over four years to develop its Marampa iron ore project in Sierra Leone, and expects first tailings output within 12 months, its CEO said.

The Marampa iron ore deposit is among Africa's biggest, but had been left largely unexploited for decades in a country still healing from a 1991-2002 civil war.

London Mining received Sierra Leone's parliamentary approval for the project, located about 75 km east (45 miles) of the capital Freetown, last month and pledged an initial investment of $80 million during 2010 to start development of a 1.5 million tonnes per year tailings starter operation.

Primary ore development of 5-8 million tonnes per year is expected by the end of 2013, the company said.

Sierra Leone President Ernest Bai Koroma said at the news conference the project marked an important step in rebuilding the West African nation's shattered economy.

London Mining's Hossie said the project will employ local workers and will have a life span of at least 30 years.

Iron ore was discovered in the Marampa area in 1926, and the deposit contains an estimated 92 million tonnes of primary ore, according to Sierra Leone's Ministry of Mines.