Kiln stopped due to disruption in raw material feed, coal mill stopped. smoldering palverized coal made its way to the baghouse. Potential ignition source was tramp metal in coal mill, CO2 inerting was effective until CO2 level in storage tank became too low to start mill system. High O2 atmosphere in baghouse due to mill off-line & lack of CO2 led to need to stop smolder w/water.