| 摘要 |
<p>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 degree C.</p> |
