The ferronickel production process closely resembles that of cement and steel. Published studies typically take the developments of the latter and adapt them to ferronickel. However, few open publications allow for a proper understanding of the calcination and reduction of lateritic nickel minerals. This research analyzes the operation of a rotary kiln calciner of 135 m length, a diameter of 6 m, and a mass flow rate between 170 and 180 t/h of partially dry mineral. The calciner uses coal as a reducing agent and natural gas as a thermal energy source. Principal component analysis (PCA) was used in a large industrial dataset to determine the variables with a greater influence on the process performance. Also, k-means clustering is used to locate operation points favorable to calcined mineral production. Results show that the most relevant variables are mineral and gas temperatures and the mass flow rates of air, mineral, natural gas, and coal.