By Pratima Desai LONDON (Reuters) – The London Metal Exchange has told some of its committee members it will not ban Nornickel’s metal from its system as the company is not under UK sanctions even though Chief Executive Vladimir Potanin is, three sources familiar with the matter said. Metal industry sources are worried a ban on Nornickel’s metals would again destabilise the LME nickel market. Disorderly trade on March 8 led to the suspension of nickel trading for over a week and the cancellation of all trades on that day. If sanctions were imposed on Nornickel the exchange would have to suspen…