Calcined petroleum coke (CPC) is created from green petroleum coke (GPC), a by-product of refining crude oil. CPC may be created using rotary kiln, hearth, or vertical shaft technology.

Calcined petroleum coke (CPC) is created from green petroleum coke (GPC), a by-product of refining crude oil. While CPC can be created using a number of processes -- including rotary kiln, hearth and vertical shaft technologies -- the high-temperature conversion from green coke to calcined coke alters the material in key three ways:

• Drying
• Release of residual hydrocarbons
• Densification

This is accomplished as the coke is heated from ambient temperature to a finishing temperature of about 1,350°C. Although initial start-up of the process uses an external fuel such as natural gas or fuel oil, the vast majority of heat required to sustain the process after start-up comes from the in-situ combustion of the residual hydrocarbons inherent in the coke, and only oxygen is needed to maintain that combustion.

CPC is an essential ingredient in the production of aluminum. In fact, every ton of aluminum needs approximately 0.4 tons of CPC, making Rain Carbon a critical "carbon link" between the refineries and the aluminum industry. CPC also is in great demand for the production of titanium dioxide (TiO₂).

Today, Rain Carbon is one of the world’s largest producers of calcined petroleum coke, with seven plants in the United States and India producing a combined 2.4 million tons per year.