Patent ID: 7404828

Claim:
A method of preparing particles of a substance, comprising: contacting said substance with a first solvent which is a C 1−4 hydrofluorocarbon in the liquid state, said hydrofluorocarbon including no chlorine atoms and having a boiling point of greater than −50° C. to form a solution of said substance in said first solvent at a pressure P 1 and subjecting said solution of said substance to a separation process which causes separation of at least some of said substance from the first solvent, said separation process comprising spraying the solution of said substance through a nozzle from said first region at a pressure P 1 into a second region at a pressure P 2 , wherein P 1 is greater than P 2 to produce a mist of small droplets of said solution of said substance in said second region at the pressure P 2 so that said first solvent evaporates from said solution of said substance in said second region so that solid particles of said substance form as a result of said evaporation; and collecting said solid particles.