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Rotary kiln

Nickel lateritic ores have high moisture contents as well as chemically bonded water in the hydroxide form. Dehydration is a minimum and some pre-reduction of the ore in a rotary kiln is used to optimize the utilization of electric power for smelting operations in the electric arc furnace. Ferronickel production therefore typically uses a rotary kiln and electric furnace process. After the saprolitic ore has been sized for treatment and partially dried, it is fed together with a solid reductant to a rotary kiln. The kilns used in lateritic processing are fired counter-currently, allowing the ore temperature to progressively increase as the ore moves towards the length of the kiln. In the lowest temperature area, the feed section, the remaining free moisture is driven off. Crystalline water is then gradually eliminated as the solid temperature increases while moving through the kiln. The remaining function of the kiln is to initiate the reduction process to minimize the energy consumption in the following process steps.