Roasting characteristics of specularite pellets with modified humic acid based (MHA) binder under different oxygen atmospheres

MHA (modified humic acid based) binder has been found as an effective substitution for bentonite in the pelletization of specularite concentrates. This study aimed to clarify the roasting behavior of specularite pellets with MHA binder under different oxygen atmospheres. The thermal behavior of the MHA binder was initially determined by TG-DSC, TG-FTIR and MRU gas analysis. The reducing gaseous products, such as CO and H2, affected the oxidation and consolidation of the specularite pellets with MHA binder due to the pyrolysis of organic matter in the MHA binder heated in air. The primary phase compositions of the specularite pellets with MHA binder roasted in N2 and 10% oxygen atmospheres were composed of hematite and magnetite, whereas there was only hematite in the pellet roasted in a 20% oxygen atmosphere. The images by optical microscopy and SEM further indicated that the oxygen content of the roasting atmosphere markedly influenced the microstructure feature of the specularite pellets with MHA binder.