Abstract: In accordance with the invention an apparatus and method are provided for curing resin-coated particles on a heated rotating surface. A single layer coating of uncured resin-coated particles is fed to the heated rotating surface. As the surface continues to rotate the uncured resin-coated particles become tacky and adhere to the rotating surface. The tack adhesion prevents the pull of gravity from separating the particles from the surface as rotation continues. Proper curing of the particles occurs on the heated rotating surface before one complete revolution is made by the surface. Cured particles are removed by a stationary scraper blade edge which rides the rotating surface and wedges between the adhering particles and the surface as the surface rotates past the edge.

Abstract: A method of manufacturing shaped rigid articles comprises preparing a mixture of thermally stable particulate material and a liquid resin having a viscosity of less than about 10 Stokes to form a thin coating of resin on the particles, at least a major portion of the particulate material comprising fly ash spheres, and forming the resulting mixture into a preselected shape with the resin bonding the particles together to form a rigid article having the preselected shape and containing less about 15% by weight resin. A rigid article also preferably has a cold tensile strength of at least about 125 psi.

Abstract: A process of coating sand with a phenolformaldehyde resin to produce a shell sand for use in shell molds and cores. The process comprises the steps of reacting phenol and formaldehyde at an elevated temperature to produce hot liquid phenolformaldehyde resin as a reaction product, transferring the hot liquid phenolformaldehyde resin to a mixing station while maintaining the resin at an elevated temperature to prevent solidification of the hot reaction product, mixing the hot liquid phenolformaldehyde resin with preheated sand at the mixing station to coat the sand with the resin, and cooling the coated sand to solidify the resin. When the phenol and formaldehyde are reacted at a location remote from the mixing station, the hot liquid phenolformaldehyde resin is transferred from the reaction station to the mixing station in insulated containers. The liquid resin is preferably maintained at a temperature of at least 250.degree. F. until it is mixed with the preheated sand.

Abstract: A process for preparing a resin-coated sand for use in shell molds and cores comprises the steps of mixing the sand with phenolformaldehyde resin and an amount of salicylic acid comprising at least about 3% of the weight of the resin, the mixing being carried out at a temperature above the melting point of the resin so as to form a coating of the resin on the sand and cooling and setting the resin on the sand to solidify the resin coating. The hot mixture of sand and resin is quenched with a mixture of water and hexamethylenetetramine, and it is preferred that at least a portion of the salicylic acid, in an amount equal to at least about 1% of the weight of the resin, be added to the hot mixture of sand and resin in the quench liquid. The sand is heated to a temperature in the range of from about 270.degree. F. to about 320.degree. F. before the sand is mixed with the resin.