Effects of K2CO3 addition on the physicochemical properties of goethite composite pellets with different basicities (CaO/SiO2)

Abstract

In this study, the effects of K2CO3 addition (0, 1, 2 wt%) on the physicochemical properties (moisture content, liquid saturation, plastic deformation degree, drop number, compressive strength) of green and (crystalline phase, fraction of melt phase, morphology, compressive strength and reduction behavior) of sintered composite pellets with varying basicities (CaO/SiO2 = 0.04, 0.40, 0.83, 1.24) were examined. The moisture content of cured green pellet with higher K2CO3 addition was greater at the same basicity. The corresponding results had a positive effect on the development of capillary state, which enhance the drop number and compressive strength up to approximately 14, 28.40 N/Pellet respectively above moisture content of 12.41 wt%. However, it was also confirmed that excessive moisture content (above 13.22 wt%) induced over liquid saturation and has negative effects on physical properties. The magnetite phase predominantly observed with increasing K2CO3 addition at fixed basicity of 0.40–1.24. Intraparticle porosity (pore size = 6.4 nm to 5 μm) decreased with higher K2CO3 addition and showed below 5% at 0.40–1.24 basicity. Interparticle porosity (pore size = 5–1100 μm) showed various behavior with K2CO3 addition at a basicity 0.04–0.40 but increased up to approximately 30% at a basicity 0.83–1.24. Compressive strength of sintered pellet tends to have negative effect on porosity. However, reduction behaviors have positive effects on higher fluxed sintered pellet due to advantageous reduction condition by impurities (alkali and alkaline earth metal cations). Obtained results help elucidate the physicochemical properties of composite pellet-containing alkali metal oxides with varying basicities.