Method of regenerating old casting sand

Abstract

A method of regenerating old casting sand consists of the steps of introducing essentially dry, used casting sand into a single container, then simultaneously subjecting the sand to rapid heating and extreme turbulence by directing a gas flame against the sand having a temperature of at least 1400.degree. C. (2550.degree. F.) along a first axis, rotating a crushing tool about a second axis parallel to the first axis and positioned such that the crushing tool does not pass through the gas flame and rotating the container about a third axis, parallel to the first and second axes. In a preferred embodiment, the container is cylindrical in shape and the third axis is inclined from the vertical at an angle of between 10.degree. and 60.degree., thereby creating upper and lower zones. The burner flame preferably is directed to the sand in the lower zone and the crushing tool is positioned to operate in the upper zone. By simultaneously contacting the oil sand with a source of intense heat and subjecting the sand to violent agitation, the binder encasing the grains of sand is rapidly embrittled and the old sand particles are subjected to thermal shock in which the boundary faces between the binder and the sand grains are subjected to stress, thereby accelerating the disintegration of the binder and its removal from the individual sand grains.