... product can be adjust. Stone mill, rock mill, ore mill:HGM Three-Rings & Medium-Speed MicroPowder MillHGM series Three-ring & Medium ... product of micro-powder mill that leads the world tide.HGM series three-ring medium speed micro-powder mill is designed ... , black lead, fluorite, phosphate rock, potassium ore, floatstone etc. When HGM mills are used to process materials with Mohs hardness between ...