Reduction of titanomagnetite(TTM)powders by H2-Ar gas mixtures was investigated under a non-isothermal condition by using a thermogravimetric analysis system.It was found that non-isothermal reduction of TTM proceeded via a dual-reaction mechanism.The first reaction was reduction of TTM to wu¨stite and ilmenite,whereas the second one was reduction of wu¨stite and ilmenite to iron and titanium dioxide.By using a new model for the dual reactions,which was in an analytical form and incorporated different variables,such as time,temperature,particle size,and hydrogen partial pressure,rate-controlling steps for the dual reactions were obtained with the apparent activation energies calculated to be 90-98 and 115-132 kJ/mol for the first and second reactions,respectively. Reduction of titanomagnetite (TTM) powders by investigated under a non-isothermal condition by using a thermogravimetric analysis system. Tit was found that non-isothermal reduction of TTM proceeded via a dual-reaction mechanism. The first reaction was reduction of TTM to w ¨ stite and ilmenite, the second one was reduction of wu ¨ stite and ilmenite to iron and titanium dioxide. By using a new model for the dual reactions, which was in an analytical form and incorporating different variables, such as time, temperature, particle size, and hydrogen partial pressure, rate-controlling steps for the dual reactions were obtained with the apparent activation energies calculated to be 90-98 and 115-132 kJ / mol for the first and second reactions, respectively.