Recycling magnesite tailings for the sustainable production of Mg2B2O5 whiskers and their application in epoxy resin

The valorization of magnesite tailings has become increasingly crucial in the context of sustainable resource management. This study investigates the synthesis of Mg 2 B 2 O 5 whiskers derived from magnesite tailings and their subsequent influence on epoxy resin (EP). It evaluates the effects of tailing characteristics, the boron-to-magnesium (B/Mg) ratio, and reaction temperature on the phase composition and microstructure of the resulting whiskers. Following the synthesis, two distinct sizes of Mg 2 B 2 O 5 whiskers were incorporated into EP to assess how whisker content, size, and surface modification techniques impact the mechanical properties, hardness, and wear resistance of the EP composites. The results reveal a complex interplay between these variables, demonstrating that an increase in the B/Mg ratio initially enhances the growth of Mg 2 B 2 O 5 whiskers, with optimal dimensions reached at a ratio of 3, beyond which a decline in aspect ratio is observed. Additionally, a reaction temperature of 800 °C is identified as critical for the formation of high aspect ratio Mg 2 B 2 O 5 whiskers, while temperatures above this threshold lead to coarsening and reduced morphological quality. Importantly, the implementation of ball milling and light calcination techniques on magnesite tailings significantly improves the quality of the magnesium source by mitigating the effects of mother salt pseudomorphs. This process results in Mg 2 B 2 O 5 whiskers with enhanced dispersibility , uniform size, and elevated aspect ratios. Although untreated Mg 2 B 2 O 5 whiskers show limited effectiveness in enhancing the tensile strength of EP, they significantly improve its hardness and tribological performance . The incorporation of 20 wt% untreated whiskers results in a 35.1 % enhancement in hardness and a remarkable 90.6 % reduction in wear rate for the EP composite. Notably, surface modification of Mg 2 B 2 O 5 whiskers with KH550 yields superior reinforcement effects. When 10 wt% modified whiskers are added, the composite demonstrates a 15.0 % increase in tensile strength coupled with a 19.3 % improvement in hardness, while maintaining a substantial 79.7 % decrease in wear rate compared to pure EP.