Effect of Elemental Sulfur on the Reduction Process of Laterite Nickel Ore under the Action of Methane

Abstract

The contradiction between the supply and demand of nickel resources is intensifying, and it is urgent to develop new processing and smelting processes for laterite nickel ore. Gas based smelting with H₂ and CH₄ as reductants is of great significance to solve the “double carbon” problem faced by the traditional metallurgical industry. Taking low-grade laterite nickel ore as the research object, CH₄ as the reductant and elemental sulfur as the additive, under the conditions of different reduction temperature, reduction time, gas concentration and additive dosage, this paper discusses the reduction behavior of CH₄ and iron nickel oxide in laterite nickel ore. Combined with XRD, SEM-EDS, gas analysis and other characterization methods, the phase and morphology of laterite nickel ore and its reduction products were deeply analyzed. Results surface: under the conditions of reduction temperature 800°C, reduction time 60 min, CH₄ concentration 20%, elemental sulfur dosage 4%, the metallization rate of nickel and iron in the reduction product can reach 98.01% and 8.44%, respectively. Nickel oxide is almost completely reduced to nickel, and most of iron is reduced to low-price iron oxide. In the reduction process, the amorphous silicate recrystallizes into magnesium olivine phase in the reduction process. It hinders further reduction of nickel. According to SEM-EDS analysis, some metal iron and elemental sulfur generate FeS around the iron oxide region, which hinders the contact between reducing gas and FeO. Therefore, the reduction of iron is inhibited and the iron oxide content increases. It promoted the selective reduction of nickel.

Fig. 13 Mechanism diagram of the reaction between CH₄ and laterite nickel ore.