The growing trend in electric vehiclesElectric Vehicles (EVs) has led to an increasing demandDemand for Class 1 nickelNickel, particularly nickelNickel sulfateSulfate, one of the critical raw materials for batteryBattery precursors. Existing pyrometallurgical technologyTechnology enables ferronickelFerronickel conversion to nickel matteNickel matte with elemental sulfur addition. Elemental sulfur, however, could potentially be replaced by alternative source of sulfur, such as gypsum (CaSO₄·2H₂O), which is more cost-effective. This study investigates the effects of process temperatures, gypsum content, and coal content in the feed on the conversion of ferronickelFerronickel to low-grade nickel matteNickel matte. Thermodynamic simulations of ferronickelFerronickel conversion to low-grade nickel matteNickel matte using gypsum and coal were conducted using FactSageFactSage 8.0 software. Furthermore, laboratory-scale experiments were conducted by melting mixtures composed of 1.5 g of ferronickelFerronickel, gypsum (ranging from 10 to 90% of the ferronickelFerronickel’s weight), and coal (at 1–2 times the stoichiometric requirement for gypsum decomposition). The mixture was placed in a magnesia (MgO) crucible and melted for 180 min under an inert argon atmosphere. The temperatures were varied between 900 °C and 1500 °C. The melting products were quenched and were analyzed using scanning electron microscopy-energy dispersive spectroscopy, and electron probe X-ray microanalysis. The findings provide insights into the effects of process temperature, gypsum content, and coal content in the feed on the phase formation and quality of the resulting low-grade nickel matteNickel matte.