JOHANNESBURG (miningweekly.com) – Platinum producer Lonmin’s No 1 furnace would remain closed for about a month, following a matte run-out on Sunday.

A full repair of the vessel of the furnace would be needed and would likely take about 30 days, the company announced on Monday.

Lonmin's share price dropped sharply on the news, falling by more than 11% to R170,80 a share in Johannesburg. The stock closed at R173,91 a share at 17:00.

The company said that a full inspection of the No 1 furnace would be conducted once temperature conditions allowed for this. The company would investigate the potential cause of the matte run-out during the inspection.

Lonmin’s three Pyromet furnaces have already been started up to mitigate the impact of the shutdown on production. The furnaces were expected to tap matte in seven days.

Lonmin said that its guidance regarding the impact of the incident on production and sales for the 2009 financial year would be given once it had completed an inspection.

In February, the company said that platinum sales for the 2009 financial year were expected to be 700 000 oz.

The No 1 is the largest of four at Lonmin’s Marikana operations and had given the company problems in the past.

In 2007, the miner announced that it would completely rebuild the furnace at a cost of R45-million – an exercise which would take 135 days, and 80 days longer than its initial expectations.

Lonmin also repaired the furnace during South Africa’s power crisis in the early part of 2008, followed by a one-week shutdown in June, after it detected a water leak.

The company rebuilt the furnace during the first quarter of the 2009 financial year.

Lonmin is the world’s third-largest platinum producer with operations in the Bushveld Complex of South Africa.

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