The effect of sulfur content of rotary kiln fuel on the composition of nickel laterite calcine

Abstract Rotary kiln-electric furnace (RK-EF) process is the main pyrometallurgical route for ferronickel production from nickel laterite ores. Coal is used as a common fuel for calcination of nickel laterites in rotary kiln. Due to the depletion of high-quality coal with low impurity content, high-sulfur coal has been used as fuel in nickel laterite rotary kilns. This investigation examines the behavior of sulfur present in the rotary kiln fuel in the calcination stage. Using coal with higher sulfur content, improving the reducing atmosphere in the furnace, and increasing the fuel consumption result in an increase in sulfur content of the nickel laterite calcine. Higher sulfur deportation from the gas phase to the calcine was observed by raising the temperature from 600 to 800 °C; however, increasing the temperature to 900 °C decreases the sulfur deportation percentage due to the recrystallization of the silicate compounds. Iron sulfide was identified as the main sulfur-containing compound in the calcine.