Process and device for cooling inorganic pigments
The present invention provides articles of manufacture and methods for making inorganic pigments. In one embodiment, the present invention provides a method for making titanium dioxide, said method comprising: (a) reacting titanium tetrachloride with oxygen in the presence of heat to produce titanium dioxide; and (b) cooling the titanium dioxide in a conduit having a helix, wherein said helix comprises at least one helical bend. Preferably the conduit comprises at least three helical bends, wherein the helix comprises at least three 360 degree spiral turns, and wherein the helix comprises an angle of from one to ten degrees. In a second embodiment, the present invention also provides a helical pipe for manufacturing pigment, comprising a conduit for receiving an inorganic pigment, wherein said conduit comprises a helix and wherein said conduit is capable of withstanding temperatures greater than about 650° C.
1 . A method for making titanium dioxide, said method comprising:
(a) reacting titanium tetrachloride with oxygen in the presence of heat to produce titanium dioxide; and
(b) cooling the titanium dioxide in a conduit comprising at least one helix, wherein said at least one helix comprises at least one helical bend.
2 . The method according to claim 1 , wherein at least one helix has a helix angle from one degree to twenty-five degrees.
3 . The method according to claim 2 , wherein the helix angle is from two to ten degrees.
4 . The method according to claim 3 , wherein the helix angle is from three to five degrees.
5 . The method according to claim 2 , wherein the helix has a constant helix angle.
6 . The method according of claim 2 , wherein the helix has a variable helix angle.
7 . The method according to claim 1 , wherein at least 10% of the conduit is helical.
8 . The method according to claim 1 , wherein at least 90% of the conduit is helical.
9 . The method according to claim 1 , wherein the conduit has at least two helical bends.
10 . The method according to claim 9 , wherein the conduit has at least three helical bends.
11 . The method according to claim 10 , wherein the conduit has at least three 360 degree spiral turns.
12 . The method according to claim 1 , wherein the conduit further comprises at least one abrupt bend.
13 . The method according to claim 1 , wherein the conduit further comprises one or more fins, vanes, rifles, depressions, spirals, or combinations thereof, and said one or more fins, vanes, rifles, depressions, spirals, or combinations thereof is located on the inside of said conduit.
14 . The method of claim 1 , further comprising using a scouring medium in the conduit.
15 . The method of claim 14 , wherein the scouring medium comprises sand, a metal halide, CsCI, compacted TiO 2 particles, calcined TiO 2 particles, or combinations thereof.
16 . The method of claim 15 , wherein the scouring medium is a metal halide and said metal halide is NaCI, KCI, or a combination thereof.
17 . A method for making titanium dioxide, said method comprising:
(a) reacting titanium tetrachloride with oxygen in the presence of heat to product titanium dioxide; and
(b) cooling the titanium dioxide in a conduit having a helix, wherein said helix comprises at least three helical bends, wherein each of said at least three helical bends comprises a 360 degree spiral turn, and wherein the helix has an angle of from one to ten degrees.
18 . A helical pipe for manufacturing pigment, said helical pipe comprising a conduit for receiving an inorganic pigment, wherein said conduit comprises a helix and wherein said conduit is capable of withstanding temperatures greater than 650° C.
19 . The helical pipe according to claim 18 , wherein the helical pipe comprises a lumen, and wherein said lumen contains titanium dioxide.
20 . The conduit of claim 18 , further comprising at least one non-helical region.