Abstract: An ammonium nitrate particle removal apparatus is joined with an exhaust gas flow of a nitrogen oxides abatement system as utilized in a nitric acid producing plant for removing ammonium nitrate particles carried in the gas flow. The apparatus includes a filter element for receiving the gas flow and substantially trapping the ammonium nitrate particles. Injection nozzles inhabit a conduit which delivers the exhaust gas flow to an inlet of the filter and inject a water mist into the gas flow which mist acts to irrigate the filter. As a result of this irrigation, the trapped ammonium nitrate particles go into solution and drop by the action of gravity to a tank or reservoir below the filter element, where the solution may be recovered for other uses as desired.