Abstract: Hydrogen-based mineral phase transformation technology is an effective method of processing refractory iron ore resources and is of great significance to the development of refractory iron ores in China. During the heating stage of the mineral phase transformation process,limonite dehydroxylates and the physical phase transforms from limonite to hematite, which has a greater impact on the subsequent reduction and milling processes,but its corresponding mechanism is less studied. In this paper,the effect of heating temperature and time on the dehydration of a typical Baozipu limonite ore during its hydrogen-based mineral phase transformation is investigated,the heat loss analysis and non-isothermal kinetic calculations were also performed using TG-DSC. The test results show that the weight loss of limonite dehydration is 5. 22% under the condition of heating temperature of 700 ℃ and heating in the air gas flow for 5 min. Non-isothermal kinetic calculations show that the apparent activation energy of the dehydration reaction of limonite is 197. 62 kJ/ mol,the most probable mechanism function is the D5 diffusion model,and the integral form is [(1 - α) -1/ 3 - 1] 2 . The main limiting link is the gas diffusion link. The key parameters and mechanism of dehydration behavior of Baozipu limonite ore in the heating stage of hydrogen-based mineral phase transformation were clarified,which provided an important basis for further understanding the process of hydrogen-based mineral phase transformation of limonite. 

Key words: limonite,dehydration reaction,thermogravimetric analysis,non-isothermal kinetics,function of mechanism