Process for reducing gangue build-up in the reactor during the chloride process that uses recycled ore
View Patent ↗The disclosure provides a process for recycling ore in the chloride process, without the build-up of silica-containing gangue in the chlorination reactor.
1. A process for preparing titanium dioxide that comprises chlorination of titanium-containing ore in a fluidized bed chlorination reactor and includes discharging from the reactor a mixture comprising metal chlorides, an unreacted titanium dioxide, a silica-containing gangue, and other components, wherein the silica-containing gangue comprises particles having a particle size greater than the particle size of at least the untreated titanium dioxide, and wherein the ratio of the unreacted titanium dioxide to silica-containing gangue is about 6:1, comprising coke, the process comprising:
(a) cooling the mixture to form particles comprising condensed metal chlorides and a solid mixture comprising the unreacted titanium dioxide, the silica-containing gangue, and the other components comprising coke;
(b) preparing an aqueous suspension of the particles comprising condensed metal chlorides and the solid mixture comprising unreacted titanium dioxide, silica-containing gangue, and other components from step (a) whereby the condensed metal chlorides are dissolved;
(c) separating the unreacted titanium dioxide and the silica-containing gangue from the other components and the dissolved condensed metal chlorides;
(d) feeding the unreacted titanium dioxide and silica-containing gangue through a screen to separate the unreacted titanium dioxide from the silica-containing gangue having a particle size greater than the particle size of at least the untreated titanium dioxide;
(e) drying the unreacted titanium dioxide; and
(f) feeding the dried unreacted titanium dioxide back to the reactor without any mechanical size reducing of the recovered titanium dioxide.
2. The process of claim 1 wherein cooling of the mixture in step (a) is accomplished using a spray condenser.
3. The process of claim 1 wherein separating in step (c) is accomplished using at least one hydrocyclone.
4. The process of claim 1 wherein screening in step (d) is wet screening.
5. The process of claim 1 wherein screening in step (d) is dry screening.
6. The process of claim 1 wherein drying in step (e) comprises dewatering.
7. The process of claim 6 wherein dewatering is accomplished in at least one hydrocyclone, belt filter, filter press or centrifuge.
8. The process of claim 7 wherein drying further comprises treatment in a rotary kiln, a fluid bed dryer, or spray dryer.
9. The process of claim 8 wherein drying is accomplished after combining with virgin ore.
10. The process of claim 1 wherein in step (d) the screen has a pore size of from 600 to 75 μm.
11. The process of claim 1 wherein in step (d) the screen has a pore size of from 300 to 105 μm.
12. The process of claim 1 wherein in step (d) the screen has a pore size of from 212 to 150 μm.