Lonmin is sharply lower, down more than 8%, after the platinum miner shut down its Number One furnace following a matte run-out yesterday.The group's initial estimate is that a full repair of the vessel is likely to take around 30 days. In order to mitigate the impact on production of this shut down and repair, the three Pyromet furnaces have already been started up and are expected to tap matte in 7 days. "A full inspection of the Number One furnace will be conducted, once temperature conditions allow, during which time we will investigate the potential cause of this incident," said the group."Once this inspection has been completed and a repair programme confirmed, a further announcement will be made."Guidance regarding the impact of this incident on production and sales for the 2009 financial year will also be given at that time, Lonmin added.Other miners are also under pressure led by Rio Tinto, Vedanta, Antofagasta and ENRC.