A rock dusting apparatus comprising: a housing; a tank mounted within the housing which comprises a removable top wall member, a sidewall member and a bottom wall member configured to form an internal tank compartment for holding and mixing a rock dust composition; a mixer positioned on the bottom wall member for mixing the rock dust composition; a tank discharge port positioned on the bottom wall member or a lower portion of the sidewall member through which the rock dust composition can be discharged from the tank; a conduit extending from the tank discharge port to a housing discharge port; the conduit comprising a pump for transporting the rock dust composition through the conduit and through a discharge line operatively connected to the housing discharge port; and one or more motors mounted within the housing for powering the mixer and the pump. The apparatus is useful for spraying rock dust compositions for suppressing propagation of a flame and/or fire caused by ignition of coal dust and/or gas within a coal mine.