Method for processing gaseous effluent streams recovered from the vapor phase oxidation of metal halides

Claim 1

A method for processing a hot gaseous effluent stream recovered from a vapor phase oxidation of a volatile metal halide to produce a particulate metal oxide thereof, said effluent stream containing a residual amount of said particulate metal oxide suspended therein, unreacted volatile metal halide vapors and by-product halogen gas comprising the steps of: contacting said hot, gaseous effluent stream with a first quantity of a recycle stream of cool, volatile metal halide, said contact causing evaporation of said first quantity of said recycle stream of cool, volatile metal halide to thereby effect a cooling of said hot gaseous effluent stream to provide a lower temperature gaseous effluent stream; subjecting said lower temperature gaseous effluent stream to separation to effect removal of at least a major portion of the residual amount of said particulate metal oxide suspended therein and provide an off-gas stream containing any remaining minor portion of the residual amount of PG,18 said particulate oxide, the unreacted volatile metal halide vapors and by-product halogen gas; contacting the off-gas stream with a second quantity of said recycle stream of cool, volatile metal halide to effect a further cooling of said off-gas stream and thereby form a mixture, said mixture comprising a liquid phase and a gas phase, wherein said liquid phase contains said second quantity of the recycle stream of cool, volatile metal halide, a major portion of condensed volatile mtal halide vapors and any remaining minor portion of the residual amount of particulate metal oxide and wherein said gaseous phase contains any remaining minor portion of the volatile metal halide vapors and by-product halogen gas; separating the liquid phase and gaseous phase from said mixture thereof, wherein said liquid phase is cooled and comprises the recycle stream of cool, volatile metal halide for contacting with said hot gaseous effluent stream and said off-gas stream; contacting said gaseous phase with a stream of cold liquid halogen to absorb the remaining minor portion of volatile metal halide vapors therein and to provide a gaseous phase of by-product halogen gas; and recovering from said stream of cold liquid halogen the remaining minor portion of the volatile metal halide vapors absorbed therein as a separate volatile metal halide liquid phase.

Claim 2

A method for processing a hot gaseous effluent stream recovered from a vapor phase oxidation of a volatile metal halide to produce a particulate metal oxide thereof, said effluent stream containing a residual amount of said particulate metal oxide suspended therein, unreacted volatile metal halide vapors and by-product halogen gas comprising the steps of: contacting said hot, gaseous effluent stream with a first quantity of a recycle stream of cool, volatile metal halide, said contact causing evaporation of said first quantity of said recycle stream of cool, volatile metal halide to thereby effect a cooling of said hot gaseous effluent stream to provide a lower temperature gaseous effluent stream; subjecting said lower temperature gaseous effluent stream to separation to effect removal of at least a major portion of the residual amount of said particulate metal oxide suspended therein and provide an off-gas stream containing any remaining minor portion of the residual amount of PG,18 said particulate oxide, the unreacted volatile metal halide vapors and by-product halogen gas; contacting the off-gas stream with a second quantity of said recycle stream of cool, volatile metal halide to effect a further cooling of said off-gas stream and thereby form a mixture, said mixture comprising a liquid phase and a gas phase, wherein said liquid phase contains said second quantity of the recycle stream of cool, volatile metal halide, a major portion of condensed volatile mtal halide vapors and any remaining minor portion of the residual amount of particulate metal oxide and wherein said gaseous phase contains any remaining minor portion of the volatile metal halide vapors and by-product halogen gas; separating the liquid phase and gaseous phase from said mixture thereof, wherein said liquid phase is cooled and comprises the recycle stream of cool, volatile metal halide for contacting with said hot gaseous effluent stream and said off-gas stream; contacting said gaseous phase with a stream of cold liquid halogen to absorb the remaining minor portion of volatile metal halide vapors therein and to provide a gaseous phase of by-product halogen gas; and recovering from said stream of cold liquid halogen the remaining minor portion of the volatile metal halide vapors absorbed therein as a separate volatile metal halide liquid phase.

Claim 9

A method for processing a hot gaseous effluent stream recovered from a vapor phase oxidation of titanium tetrachloride to produce pigmentary titanium dioxide, said effluent stream containing a residual amount of solid, pigmentary titanium dioxide suspended therein, titanium tetrachloride vapors and chloride gas comprising the steps of: contacting said hot, gaseous effluent stream with a first quantity of a recycle stream of cool, previously recovered, unreacted titanium tetrachloride, said contact causing evaporation of said first quantity of said recycle stream of cool titanium tetrachloride to thereby effect a cooling of said hot gaseous effluent stream to provide a lower temperature gaseous effluent stream; subjecting said lower temperature gaseous effluent stream to separation to effect removal of at least a major portion of the residual amount of solid, pigmentary titanium dioxide suspended therein and provide an off-gas stream containing any remaining minor portion of the residual amount of solid, pigmentary titanium dioxide, the titanium tetrachloride vapors and chlorine gas; contacting the off-gas stream with a second quantity of said recycle stream of cool titanium tetrachloride to form a mixture, said mixture comprising a liquid phase and a gas phase, wherein said liquid phase contains said second quantity of the recycle stream of cool titanium tetrachloride, a major portion of condensed titanium tetrachloride, a major portion of condensed titanium tetrachloride vapors and any remaining portion of the residual amount of solid, pigmentary titanium dioxide and wherein said gaseous phase contains any remaining minor portion of the titanium tetrachloride vapors and chlorine gas; separating the liquid phase and gaseous phase from said mixture thereof, wherein said liquid phase is cooled and comprises the recycle stream of cool titanium tetrachloride for contacting with said hot gaseous effluent stream and said off-gas stream; contacting said gaseous phase with a stream of cold, liquid chlorine to absorb the remaining minor portion of volatile titanium tetrachloride vapors therein and to provide a gaseous phase of by-product chlorine gas; and recovering from said stream of cold, liquid chlorine the remaining minor portion of the titanium tetrachloride vapors absorbed therein as a separate titanium tetrachloride liquid phase.

Claim 10

A method for processing a hot gaseous effluent stream recovered from a vapor phase oxidation of titanium tetrachloride to produce pigmentary titanium dioxide, said effluent stream containing a residual amount of solid, pigmentary titanium dioxide suspended therein, titanium tetrachloride vapors and chloride gas comprising the steps of: contacting said hot, gaseous effluent stream with a first quantity of a recycle stream of cool, previously recovered, unreacted titanium tetrachloride, said contact causing evaporation of said first quantity of said recycle stream of cool titanium tetrachloride to thereby effect a cooling of said hot gaseous effluent stream to provide a lower temperature gaseous effluent stream; subjecting said lower temperature gaseous effluent stream to separation to effect removal of at least a major portion of the residual amount of solid, pigmentary titanium dioxide suspended therein and provide an off-gas stream containing any remaining minor portion of the residual amount of solid, pigmentary titanium dioxide, the titanium tetrachloride vapors and chlorine gas; contacting the off-gas stream with a second quantity of said recycle stream of cool titanium tetrachloride to form a mixture, said mixture comprising a liquid phase and a gas phase, wherein said liquid phase contains said second quantity of the recycle stream of cool titanium tetrachloride, a major portion of condensed titanium tetrachloride, a major portion of condensed titanium tetrachloride vapors and any remaining portion of the residual amount of solid, pigmentary titanium dioxide and wherein said gaseous phase contains any remaining minor portion of the titanium tetrachloride vapors and chlorine gas; separating the liquid phase and gaseous phase from said mixture thereof, wherein said liquid phase is cooled and comprises the recycle stream of cool titanium tetrachloride for contacting with said hot gaseous effluent stream and said off-gas stream; contacting said gaseous phase with a stream of cold, liquid chlorine to absorb the remaining minor portion of volatile titanium tetrachloride vapors therein and to provide a gaseous phase of by-product chlorine gas; and recovering from said stream of cold, liquid chlorine the remaining minor portion of the titanium tetrachloride vapors absorbed therein as a separate titanium tetrachloride liquid phase.