Patent ID: 7740775

Claim:
A process for preparing particles of a substance, said process comprising providing a mixer having a first inlet connected to a first solvent source comprising a first solvent being a C 1-4 hydrofluorocarbon with a boiling point less than 20° C. and more than −90° C., having a second inlet connected to a second solvent source comprising a second solvent being a C 1-4 hydrofluorocarbon with a boiling point less than 20° C. and more than −90° C., having a third inlet connected to a source of a first formulation being a solution of the substance in a carrier solvent, and having an outlet connectable to a separation means for separating particles of the first substance from the first and second solvents, and extracting the carrier solvent from the formulation and precipitating the substance as particles by introducing said first formulation in the form of a stream into said mixer via said third inlet, introducing said first solvent in the form of a stream into said mixer via said first inlet at a rate such as to contact 1 volume of said formulation with greater than or equal to 1 volume of said first solvent to thereby form a mixture of the first formulation and the first solvent, and subsequently introducing said second solvent in the form of a stream into said mixer via said second inlet at a rate such as to contact 1 volume of the so-formed mixture of the first formulation and the first solvent with 8-25 volumes of said second solvent, the pressure of the first and second streams of C 1-4 hydrofluorocarbon solvent being 1 to 5 bar G above the vapour pressure of the C 1-4 hydrofluorocarbon solvent at the operating temperature, the substance being insoluble or only sparingly soluble in the first and second solvent streams, thereby causing formation of solid particles of the first substance by extraction of the carrier solvent and precipitation, wherein both the first and second solvent streams are in a non-supercritical state, and subjecting the resultant mixture to a separation process which causes separation of the first substance from the mixture of carrier solvent and first and second solvent streams; and wherein contact between the first formulation and the first solvent stream is achieved by means of a mixer comprising three concentric tubes, a first of said concentric tubes being connected to the said first inlet for said first solvent, a second of said concentric tubes being connected to the said second inlet for said second solvent, a third of said concentric tubes being connected to the said third inlet for said first formulation, each of said three concentric tubes having an outlet, wherein the first solvent stream is fed through said first of said three concentric tubes, the second solvent stream is fed through said second of said three concentric tubes, and the first formulation is fed through the third of said three concentric tubes, and the outlets of the three concentric tubes are designed to effect contact between the first formulation, the first solvent stream and the second solvent stream.