Method and apparatus for cryogenic removal of solid materials

Abstract

A method and apparatus for cryogenic removal of solid materials includes a wand connected in fluid communication with a cryogen fluid source. The wand directs the cryogen against a selected portion of solid material. The wand has a spray nozzle to direct the spray against an inner exposed surface of energetic material typically contained within a munition casing. The wand is connected to a mounting element to allow movement of the wand within the munition body. The munition is mounted on a rotatable base for rotating the munition and to expose the material to the cryogenic fluid spray. The cyrogenic fluid spray, such as liquid nitrogen, is utilized in a dry washout process to freeze and embrittle the surface layer either by precooling and fluid spray, or by spray alone. The embrittle layer is then eroded away by the spray into small particles for removal by pneumatic transport, vacuum, or other collection and removal system. A mechanism may be provided for vibrating the material to loosen the particles. In addition, adjustable abrading elements may engage and remove additional amounts of embrittled material. To conserve the amount of liquid nitrogen, compressed air or gas simultaneously or in alternating succession with jets of liquid nitrogen may be utilized further to fracture and remove the embrittled particles. The probe may be made of a material to establish electrical contact between the solid material and the wand to remove static electricity from the material.