** Shares of Australian coal miners help prop up the domestic mining sub-index .AXMM

** China, top consumer of coal, hit back at the U.S. with retaliatory tariffs, which includes a 15% levy on U.S. coal

** Coal duty is expected to increase the commodity's price

** Shares of Whitehaven Coal WHC.AX, Australia's largest independent coal miner, rise 2.9% to A$6.275, jumping the most since Jan. 14

** Stanmore Resources SMR.AX jumps 2.4% to A$2.765, most since Jan. 14, while Coronado Global Resources CRN.AX is up 3.4%

** Aussie mining index .AXMM is up 1.8%

(Reporting by Nichiket Sunil in Bengaluru)

((Nichiket.Sunil@thomsonreuters.com;))