Abstract: A defoamer composition including a primary antifoam agent which includes a particulate-type material having a high surface area such as silica, a secondary antifoam agent for acting synergistically with the primary antifoam agent such as polydimethylsiloxane, a water carrier, and a quaternary ammonium salt silane compound which functions as an antimicrobial agent, fixed and adhered to the surface of the particulate material, in order that the defoamer composition be resistant to biological degradation due to the presence in the system of microorganisms. Methods of defoaming cationic, anionic, and nonionic surfactant produced foams are disclosed, as is a method of rendering silica hydrophobic.

Abstract: Described are a method and apparatus for freezing molten metals and metalloids in particulate or flake form at very rapid cooling rates. A volatile coolant liquid is fed to the center of a rapidly rotating disc-like member to create an outwardly flowing film of coolant across the surface of the member. The material to be processed is fed to the coolant film at a location spaced from the center and is thrown outwardly by centrifugal forces while being cooled by vaporization of the liquid. The rotating member may include upwardly projecting vanes for collision with the outwardly flowing material to produce a higher surface area product.