A South African State development bank is considering taking a majority stake in the local unit of ArcelorMittal South Africa (AMSA) as it tries to halt the planned closure of two steel mills crucial to the nation's manufacturing sector. The Industrial Development Corporation (IDC), which already holds 8.2% of AMSA, is willing to inject more capital into the struggling company in exchange for boosting its holding, according to people familiar with the matter who asked not to be identified because the plans are at an early stage and not yet public.