Mining firm Impala Platinum recorded a 52 percent drop in profit in the last 12 months, hit by higher labour costs and weak demand, results released Thursday showed. Chief executive Terence Goodlace described the year as \"challenging\" in terms of \"a changing work workforce dynamic and weak market prices\". The world\'s second platinum producer booked earnings of $194 million as higher wages decimated slightly higher revenues. The company\'s Impala mine, in the platinum belt of Rustenburg, has for a large part of 2012 and this year suffered a wave of strikes for higher salaries, resulting in work stoppages. \"Above inflation wage and power cost increases combined with lower production affected unit costs.\" Early this year this year, the troubled mine briefly fired more than 17,000 workers who took part in an illegal strike. Some 8,500 were rehired after negotiations with unions. Despite the challenges, production of platinum was up nine percent to 1.58 million ounces. The company said lower dollar metal prices and demand for platinum metals impacted performance, with the market expected to remain constrained. The Johannesburg based firm also has operation in Zimbabwe, where it has entered into an agreement with the government to transfer its majority shares to the public, under the controversial equity laws.