Process for mixing liquid additives with solid materials under sonic velocity conditions

A process for the continuous and uniform mixing of relatively small amounts of liquid or liquefied additive with relatively large amounts of solid granular material comprising:

• forming, in a conduit, a continuous pneumatic- or gravity-borne stream of said solid granular material;
• passing an inert gas stream through a constricting orifice to maintain sonic velocity flow conditions therein;
• concurrently introducing a stream of said liquid or liquified additive into said inert gas stream in said constricting orifice under conditions such that combined stream sonic velocity flow conditions are maintained;
• introducing the resulting combined liquid or liquified additive and inert gas streams into said conduit to effect addition of said liquid or liquified additive to said solid granular material as a coating thereon, providing a gas-tight reservoir for said liquid of liquified additive, and supplying said additive to said constricting orifice by forcing said additive from said reservoir by pressurizing said reservoir at pressure substantially equal to the pressure of said inert gas stream.