London-based platinum producer Lonmin is closing two of its high-cost, loss-making shafts and cutting 6000 jobs - a fifth of its workforce - as it struggles to protect its balance sheet at the bottom of the platinum price cycle. Giving the company's third-quarter production update on Friday, CEO Ben Magara said that by month-end 1355 workers would leave Lonmin, with another 4500 expected to take voluntary severance packages.The company, experiencing negative earnings with platinum prices under the $1000-an-ounce mark, is maintaining production and unit costs in line with guidance for the year, but has seen the price of platinum drop 20% this year, albeit with a small benefit from the rand's depreciation against the dollar.story_article_left1With its balance sheet under threat, investor fears of a third rights offer in six years have been demonstrated by a further 57% fall in the value of Lonmin's shares through the course of this year, leaving the company trading at a fraction of its price to book value.Last month, Glencore handed over its 24% stake in Lonmin to shareholders, which precipitated a 9% fall in the Lonmin share price in one day.With Lonmin facing a series of maturing revolving credit facilities, Magara said he was unable to say more than that the board was "reviewing the company's capital structure and looking at all the long-range options" to see the company through the cycle.Investors will have to wait until Lonmin's annual results in November to learn of the company's plans to remain sustainable through the metal's downturn. Magara said he expected the low-price environment to persist for two years."The supply base must take action." Taking out 10% of ore production and 8% of metal output would go some way to alleviating its struggles, as would the Rowland shaft's good performance and production ramp-up at the Saffy shaft, but he said job losses would be inevitable to maximise liquidity.story_article_right2The company's trading statement said mining operations in the third quarter of the financial year were held back by an increase in the frequency and duration of Section 54 safety stoppages, in particular at K3, the biggest shaft."Saleable platinum metal in-concentrate at 172672 ounces was 149054 ounces higher than the prior year", during which there was a strike.The Hossy and Newman shafts will be shut, cutting production by 100000 ounces a year, with other shafts placed under care and maintenance.The National Union of Mineworkers (NUM) said it was "shocked and saddened" to hear of the job cuts and shaft closures. The NUM said it believed mine owners made such decisions "easy" [sic] and it would "engage the company to save jobs".Magara said Lonmin had put in three years of "hard work" rebuilding relationships with its workforce and community after 44 people were killed at or near its Marikana operation. PeacockB@sundaytimes.co.za..