Effect of lime addition on the mineral structure and compressive strength of magnesium containing pellets

Addition of MgO in pellets was proved to have an unfavorable effect on the compressive strength of roasted pellets. For increasing the strength of magnesium containing pellets, lime was further added to prepare pellets with different basicity. SEM-EDS, XRD and Rietveld refining were applied to study the phase composition and microstructure of pellets. Results showed that the compressive strength of roasted lime added pellets was higher than magnesium containing pellets, which increases firstly and then decreases with the increase of basicity. The pellets with a basicity of 0.4 had a maximum strength and a minimum porosity, which were 3318 N/pellet and 18.92% respectively. Under a similar strength level, lime added pellets with a basicity of 0.6 had a higher porosity than magnesium containing pellets, which were 22.11% and 28.32% respectively. Compressive strength of roasted pellets is affected by the incompletely mineralized magnesium olivine, pores, liquid phase, as well as (Mg,Fe)O center dot Fe2O3 phase. (C) 2020 Elsevier B.V. All rights reserved.