Investigation of pre-oxidation vacuum decarburization process of high carbon ferromanganese

•Pre-oxidation vacuum decarburization process was employed to treat ferromanganese.•Low carbon ferromanganese with 0.47% C was obtained.•The volatilized manganese could be collected to decrease volatilization loss.

Pre-oxidation vacuum decarburization process was employed to decarburize high carbon ferromanganese. In pre-oxidation stage, the degree of oxidation was controlled by changing roasting time and 13.17% carbon was removed. In the vacuum decarburization stage, C in ferromanganese and O captured in pre-oxidation stage further reacted to decarburize ferromanganese by increasing reaction temperature and prolonging time. The ferromanganese with 0.47% carbon was obtained after the ferromanganese with 6% carbon was roasted for 3 h at 600 °C and decarburized at 1100 °C, 25 Pa for 4 h. At the same time, 19.28% manganese volatilized and was collected as condensate that would compensate the loss of Mn in the low carbon ferromanganese product. Preparing ferromanganese products with different carbon content will be realized by adjusting the technical parameters, such as holding time and temperature, in pre-oxidation and vacuum decarburization procedures respectively.