Enhanced Chromium Recovery in the Smelting of Ferronickel Along with Energy-Saving: An Industrial Case Study

The rotary kiln-electric furnace process accounts for two-thirds of the global nickel output. The raw laterite nickel ore contains approximately 1–5 wt.% Cr 2 O 3 , but its recovery is limited during smelting. Due to the inefficient utilization, the accumulated Cr-containing slags are potential environmental risks. This work provides positive results regarding enhanced chromium recovery in the ferronickel-making process by controlling the slag formation. The coordination of the quaternary basicity [= R 4 = m(CaO + MgO)/m(SiO 2 + Al 2 O 3 )] and FeO content of slag was performed in pilot-scale and industrial tests. The results confirmed that the chromium grade in the ferronickel increased from 0.5 ± 0.1 wt.% to 2.8 ± 0.2 wt.% after regulating the quaternary basicity from 0.58 ± 0.01 to 0.69 ± 0.01 and the FeO content from 5.0 ± 0.5 wt.% to 7.0 ± 0.5 wt.% in the smelting slag. Meanwhile, the temperature for smelting could be decreased by nearly 35°C, and the corresponding energy consumption decreased by approximately 660 Kw·h/t-ferronickel.