Johannesburg - A joint venture between ferrochrome producer Merafe Resources and London-listed Xstrata will shut five of its furnaces until the end of May to help power utility Eskom manage a tight electricity supply. The companies said 100 000 tonnes of production would be lost as a result of the agreement, but there would be no impact on supplies to customers in the second quarter. Eskom would buy back the energy that would have been used by the furnaces, they added. The companies said the furnaces will undergo maintenance during the shutdown and there would be no job losses. They said the Rustenburg smelter’s energy efficiency is expected to improve when a new sintering and pelletising plant, currently under construction, becomes operational in the second half of this year. South Africa has been struggling to meet demand for power as new power plants meant to plug the shortfall have been delayed. Supply will remain vulnerable until the first units of Eskom’s new stations become operational next year. The national grid nearly collapsed four years ago, forcing mines and smelters to shut for days and costing the economy billions of rands in lost output.