Abstract: A method of calcining in a fluidized reactor wherein fluid petroleum coke is utilized as the reactor fuel. The method of the present invention utilizes fluid coke as the fuel for a calcining reactor. The fluid coke is introduced into the pneumatic stream with the lime feed material, ahead of the reactor feed header, to achieve an intimate mixing of the fuel and the feed material. This facilitates calcination of the calcium carbonate and results in more efficient utilization of fuel than in methods of the prior art. Advantages of using fluid coke as the fuel include that it is of a size fine enough to provide efficient utilization as a fuel but not so large that inefficient utilization, unstable temperatures, and carry-over into the final product result. Another advantage is that the fluid coke typically contains 5-7% by weight sulphur, a necessary ingredient in proper calcination of calcium carbonate in a fluidized reactor and one that has been required to be added in methods of the prior art.