Work at the Gupta-owned Optimum Coal Mine in Mpumalanga came to a standstill on Wednesday as workers marched to hand over a memorandum of grievances to CEO George van der Merwe.The mine supplies coal to power utility Eskom for its power generation.National Union of Mineworkers (NUM) spokesman Livhuwani Mammburu said its members wanted answers on the future of the mine because of reports that the mine’s owners‚ the Gupta family‚ could not be found.Mammburu said the workers wanted to be reassured about the future of the mine and whether it would be sold."They also want to know whether they will be … paid this upcoming Friday as the Bank of Baroda‚ which handled their payments‚ is about to close its operations in SA‚" Mammburu said.He said the workers could not hand over the memorandum because Van der Merwe was said to be in Johannesburg."There is no work here. The workers will come back tomorrow to hand over the memorandum. There is a total shutdown of the operation‚" he said.