Suppression of the formation of noxious substances during chloride processes
View Patent ↗The present invention is directed to the suppression of the formation noxious compounds such as furans. According to the present invention, a venturi device is used to rapidly quench a chlorinator reaction gas. The rapid quench minimizes the resonance time that furan precursors are at conditions conducive to furan formation.
1. A process for suppressing the formation of noxious compounds produced during TiO 2 production, said process comprising: (a) permitting a chlorinator reaction gas to enter a nozzle, wherein said nozzle is comprised of a converging section and a diverging section; (b) permitting said chlorinator reaction gas to pass from said converging section of said nozzle to said diverging section of said nozzle; (c) introducing a temperature reducing substance into said nozzle thereby cooling said gas to form a mixture comprised of solids and a gas; and (d) separating said solids from said gas.
2. The process of claim 1 , wherein said chlorinator reactor gas is comprised of reaction products generated during the chlorination of titania ore.
3. The process of claim 2 , wherein said chlorinator reaction gas is further comprised of at least one substance selected from the group consisting of nitrogen, carbon dioxide, carbon monoxide, hydrogen chloride, ferrous chloride and manganous chloride.
4. The process of claim 3 , wherein said chlorinator reaction gas is further comprised of at least one substance selected from the group consisting of coke fines, unreacted ore and silica.
5. The process of claim 1 , wherein said temperature reducing substance is comprised of titanium tetrachloride.
6. The process of claim 1 , wherein said chlorinator reaction gas enters said converging section of said nozzle at a temperature between 800° C. and 1000° C.
7. The process of claim 1 , wherein said chlorinator reaction gas is cooled to a temperature between 240° C. and 280° C.
8. The process of claim 1 , wherein said separating occurs at a cyclone.
9. The process of claim 1 , wherein said nozzle is a venturi device.
10. A process for suppressing the formation of furans during titanium dioxide production, said method comprising: (a) permitting a chlorinator reaction gas to enter a converging section of a venturi device, wherein said chlorinator reaction gas is at a temperature between 700° C. and 1100° C. when entering said converging section and is comprised of titanium tetrachloride; (b) permitting said gas to pass to a diverging section of said venturi device; (c) introducing liquid titanium tetrachloride into said venturi device thereby cooling said chlorinator reaction gas to a temperature between 240° C. and 280° C. to form a mixture comprised of solids and a gas; and (d) cycloning said mixture.
11. The process according to claim 10 , wherein said solids of (c) are filtered to form a filter product that has a total equivalent concentration of furans of less than 100 nanograms per kilogram.
12. The process according to claim 11 , wherein said total equivalent concentration of furans is less than 40 nanograms per kilogram.
13. The process according to claim 12 , wherein said total equivalent concentration of furans is less than 20 nanograms per kilogram.