SHANGHAI, May 15 (SMM) - On May 15, premiums of Jinchuan nickel were 11,000-11,500 yuan/mt. The average premium stood at 11,250 yuan/mt, flat from the previous trading day. NORNICKEL nickel was quoted at premiums of 6,000-6,500 yuan/mt, with an average of 6,250 yuan/mt, down 50 yuan/mt from a day ago. Jinchuan nickel surged on low supply, and the prices may fall somewhat with the ease of supply tightness in the middle of the week. Spot trades improved today on low futures prices.  Nickel briquette prices were 173,900-174,500 yuan/mt, an increase of 1,700 yuan/mt from the previous trading day. The nickel briquette transactions were slack as it was still traded at premiums over nickel sulphate.