Abstract: In this study, using dolomite as a representative carbonate mineral, the catalytic hydrogenation and thermal decomposition reduction process of carbonates under a hydrogen gas atmosphere were explored by mechanically mixing Ni/γ-Al₂O₃ catalyst with dolomite. The effects of n_Ni/n_Al, blending ratio, gas velocity, hydrogen concentration, reaction temperature, and stacking method of catalyst and magnesite on the reaction performance were investigated. The results showed that the Ni/γ-Al₂O₃ catalyst could significantly improve the conversion efficiency of carbonates, and \varphi_\mathrmCO/\varphi_\mathrmCO_2 in the gas products increased from 1.105 without the catalyst to 2.622 with the catalyst. However, excessive nickel content, high hydrogen concentration, and low reaction temperature all promoted the formation of CH₄ and reduced the selectivity of CO. The use of magnetism for the separation of catalyst and solid products was employed to enable multiple cycles of reactions, and the catalyst maintained its activity and selectivity after multiple cycles.