The bonding mechanism and effects of sodium ligninsulfonate (SL) in iron ore pelletization

Abstract

Bentonite is the most commonly used binder for iron ore pellets. However, due to its high alumina and silica content, the slag volume and energy consumption are increased. The aim of the present work is to identify the CSL (sodium ligninsulfonate added CaCO3) as an alternative binder in iron ore pelletization. FTIR and zeta potential tests verified that sodium ligninsulfonate (SL) reacted with magnetite mainly through ligand exchange, hydrogen bond and electrostatic interaction. Compared with SL, CSL has more active sites and stronger adsorbability. The strength of CSL preheated and roasted pellets was determined by TG and SEM. CaCO3 as a fluxing agent develops oxide bridging and bonding between the magnetite grains, forming more slag, reducing porosity and improving the compressive strength of roasted pellets. The experimental results show that it is feasible to add CaCO3 in SL as binder in pellet production.