Reduction of Carbon Footprint Through Hybrid Sintering of Low-Grade Limonitic Nickel Laterite and Chromite Ore

摘要

In this paper, low-grade limonitic nickel laterite and chromite were synergistically utilized via the hybrid sintering process (i.e., pellet-sintering process) for high-quality Ni-Cr sinter preparation and great carbon emission reduction. Under the optimum process conditions, Ni-Cr sinter indices were substantially improved in the pellet-sintering process. Tumble index and productivity were improved by 33.57% and 27.84%, respectively, and solid fuel rate was reduced by 16.02% compared with the base case. CO2 emissions can be annually reduced by 112.62 thousand tons in sinter production for a major Chinese stainless steel enterprise. This was due to that the better heat and mass transfer conditions during pellet-sintering was beneficial to the reduction of sinter porosity and the formation of silico-ferrite of calcium and alumina, which consequently contributed to the generation of Ni-Cr sinter with more compact microstructure at lower solid fuel consumption. Its reduction characteristics were similar to the base case whereas the softening-melting properties were even better. In addition, Fe-Cr-Ni crude alloy formed in the determination process of softening-melting properties possessed the appropriate melting point, which was suitable for blast furnace production. The high-quality Ni-Cr sinter obtained from the low-carbon pellet-sintering process can be used as the qualified burden for Fe-Cr-Ni alloy smelting at lower cost.