Abstract: Vaporized silicon halide is mixed with a vaporized alkali metala in a reactor chamber in an exothermic reaction producing liquid silicon droplets and gaseous alkali metal halide, and then passed out of the reactor chamber through a nozzle in a supersonic jet. The supersonic jet is produced by utilizing vacuum means to maintain the exit chamber at a lower pressure than the reactor chamber. Separation of the silicon from the salt by-products is performed by shock wave impaction separation technique wherein the products of the complete reaction between the alkali metal and silicon halide are made to impinge upon an unrestricted, flat surface so that the direction of flow of the gas changes abruptly and a shock zone is created above the flat surface. The silicon droplets are carried by their large forward momentum through the shock zone onto the separating surface where they are deposited. The gaseous alkali metal halide flows across the surface and is thus separated from the silicon product.