MOSCOW, June 28 (Reuters) - Russian billionaire Vladimir Potanin, majority shareholder in mining giant Nornickel , said on Monday that the impact of new duties on the company is expected at around $0.5 billion, the RIA news agency reported. Russia has introduced temporary new export taxes for steel products, nickel, aluminium and copper which will cost their producers $2.3 billion between Aug. 1 and Dec. 31. (Reporting by Anastasia Lyrchikova; Writing by Polina Ivanova; Editing by Jan Harvey) Our Standards: The Thomson Reuters Trust Principles.