A rotary
kiln-electric furnace is the predominant process for producing
ferronickel from nickel laterite ore. Fuel combustion in the rotary
kiln generates sulfur dioxide, which subsequently leads to the transfer
of sulfur from the kiln atmosphere to the solid calcine. The presence
of sulfur in ferronickel causes the formation of inclusions, which
negatively impact the mechanical properties of the final alloy. Depletion
of high-quality coals results in using low-quality ones, which typically
contain high levels of sulfur. This study examines the application
of calcium carbonate as an absorbent of sulfur, resulting from burning
coal in the nickel laterite calcination kiln. Calcium sulfide is found
to be the main product of the sulfurization reactions. The addition
of calcium carbonate significantly decreases %S in calcine with sulfur
removal in the range of 70.8–91.0%. By increasing the processing
time from 30 to 120 min, sulfur reduction decreases from 91.0 to 78.3%.
Increasing the temperature from 700 to 800 °C enhances sulfur
reduction from 77.3 to 88.8%. However, sulfur reduction decreases
to 70.8% as the temperature reaches 900 °C.