Effect of manganese ore and basicity on the enhanced reduction and consolidation characteristics of nickel–chromium bearing reduced pellets.

[Display omitted] • Enhanced reduction and compressive strength of nickel–chromium-manganese reduced pellets was realized. • Thermodynamics analysis of the main metallic oxides was studied. • Phase transformation and microstructure evolution of reduced pellets were clarified. • The mechanism of reduction and consolidation strengthening for the reduced pellets was disclosed. For increasing the reduction degree and compressive strength of nickel–chromium-manganese bearing reduced pellets, the manganese ore and calcium oxide were applied as additives to improve the reduction and consolidation characteristic. The thermodynamics analysis and systematic process mineralogy were also conducted to further determine the related strengthening mechanism. The results showed that compared with no manganese ore and natural basicity, the compressive strength, reduction degree of pellets, iron and nickel for the reduced pellets can reach from 58 N per pellet, 56.21 %, 71.29 % and 91.45 % to 489 N per pellet, 69.58 %, 88.21 % and 98.55 % respectively with 5 % manganese ore and 0.30 binary basicity. MnO and CaO can improve the reduction of iron oxides. Meanwhile, during the reduction process, the low-melting-point phases can generate in the prereduced pellets, which can act as binding phases to wet and tighten the solid particles around through surface tension. The enhanced ways can accelerate the reduction of multi-metal bearing phases, growth of α (Fe, Ni) and solid phase reaction of adjacent particles, resulting in an improvement of reduction degree and compressive strength for the nickel–chromium-manganese bearing reduced pellets. [ABSTRACT FROM AUTHOR]