Size, distributing, morphology and number of the MA island influencing yield ratio, yield strength and DWTT of the pipeline steel are introduced in the paper by analyzing influence of the MA island on mechanical properties in X70 and X65 pipeline steel.

The developed Research on accelerant for difficult floated coal of floatation MA accelerant is suitable for the floatation of the non difficult floated coal and difficult floated coal,especially for the difficult floated coal with obvious results.