Abstract: The main extraction factors of chromite ore were studied by decomposing the chromium in NaOH sub-molten salt system，and the optimum process parameters were deterimined.Results showed that reaction temperature and oxygen partial pressure were the most significant factors on chromium extraction efficiency.Under the conditions of particle size among 0.038~0.048 mm，mass ratio of ore to NaOH of 1∶7，and agitation speed of 650 r/min，the optimal conditions of decomposing the chromium in NaOH sub-molten salt system were obtained as follows：the reaction temperature was 245 ℃，the NaOH so- lution content was 65%（mass fraction），the oxygen partial pressure was 0.8 MPa，and the reaction time was 480 min.Under the optimal conditions，the chromium extraction rate was above 99%.The macro-kinetic investigation revealed that the leach- ing process was controlled by reactant diffusion in the solid product layer and described by 1-2/3x-（1-x）2/3=2 124.73× P■0.85×e-51 490/RT×t with apparent activation energy of 51.49 kJ/mol.

Key words: chromite ore, NaOH, sub-molten salt, kinetics