Rain Carbon's calcined petroleum coke is a key raw material in the production of titanium dioxide (TiO2), a white powder with a high brightness and opacity that is widely used as a pigment in many every-day consumer applications.
The primary application is in paint, where TiO2 powder is used as the base pigment for construction and automotive applications paints. TiO2 also is used as a filler in plastics, coatings, cosmetics, toothpaste and sunscreen.
Rain Carbon supplies high-carbon Calcined Petroleum Coke (CPC) produced at our Rain CII plants, which is essential as a reducing agent in the manufacture of titanium dioxide via the chloride process.
Titanium containing ore such as rutile and ilmenite is mixed with CPC and fed to a high temperature fluid-bed reaction vessel known as a chlorinator, which heats the materials to 1,000˚C (18,320˚F). Chlorine gas is added, and the high-purity carbon present in CPC reduces the TiO2, which then reacts with the chlorine gas to produce TiCl4 via the reaction below:
TiO2 + C + 2Cl2 → TiCl4 + CO2
The TiCl4 is recovered and then distilled to generate purified TiCl4. This is then reoxidized to pure TiO2 using oxygen gas. The chlorine gas generated in the reoxidation step is recovered and re-used in the process. The fine-particle size TiO2 product typically undergoes milling, and small amounts of proprietary, surface modifying chemicals are added to produce a variety of product grades for use in a wide range of coating and filler applications.
The quality requirements for the CPC used in TiO2 applications are not as demanding as those for anode production. Significantly higher vanadium and nickel levels can be tolerated, and CPC with a shot structure is preferred over a sponge structure, since shot CPC is harder and contains a lower percentage of fines (-100 mesh or -150µm). Fines are undesirable in TiO2 production as they pass straight through the chlorinator and create a carbon loss. Shot CPC typically has a much tighter particle-size distribution than sponge CPC, suffers less attrition and generates fewer fines due to handling when compared to sponge CPC.