Experiment on strengthening sintering performance of laterite nickel ore by separated granulating and separate fuel adding

In the sintering production of laterite nickel ore, in order to realize the comprehensive utilization of resources, sintering dust, blast furnace gravity ash, fine particle return mine and other materials are often added in the batching process. However, these materials are easy to have adverse effects on the permeability and sintering performance of the layer due to poor granulating. In order to improve the permeability of the layer and sintering performance, the sintering dust, gravity ash of blast furnace and fine particle return mine were separated granulated. In addition, in order to prevent the pellets from underburning, the fuel was added separately to the separated granulating materials. The effects of separated granulating and separate fuel adding on the permeability of layer and sintering performance were studied by sinter pot experiment. The process mineralogy of sinter was analyzed by X-ray diffraction and metallographic microscope, and the related mechanism for strengthening sintering of laterite nickel ore was revealed. The results show that, compared with the reference, when 30% of anthracite is added into separated granulating, the average particle size of mixture increases from 4.18 mm to 5.99 mm, and the layer permeability index increases from 0.233 to 0.482. At the same time, the sintering performance is greatly improved, the sintering yield increases from 68.69% to 79.37%, the tumbler index increases from 51.73% to 60.82%, the vertical sintering speed increases from 24.44 mm/min to 33.48 mm/min, the productivity increases from 0.77 t/(m²·h) to 0.99 t/(m²·h), and the solid fuel consumption decreases from 147.10 kg/t to 130.29 kg/t. The process mineralogy shows that compared with the reference, the pores and cracks of the separated granulating sinter are greatly reduced and the microstructure is more dense. Meanwhile, the wetting degree between the main solid phase iron spinel and the liquid phase is improved, and the acicular and interleaved SFCA are increased, therefore the consolidation conditions of sinter are greatly improved.