Recycling Welding Fluxes: A Case Study into Manganese-Silicate System

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2024-12, Vol.55 (6), p.4398-4407
• Main Authors: Tian, Huiyu, Zhang, Yanyun, Shi, Shuai, Wang, Guanyi, Wang, Cong
• Format: Article
• Language: English
• Subjects: Alloying elements; Amorphous structure; Characterization and Evaluation of Materials; Chemistry and Materials Science; Depolymerization; Heat treating; Materials Science; Metallic Materials; Nanotechnology; Original Research Article; Recycling; Silicon dioxide; Slag; Structural Materials; Submerged arc welding; Surfaces and Interfaces; Thin Films; Weld metal; Welding fluxes
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-024-03252-6

Recycling presents a waste-free solution to substantial disposal of welding slags which retain most components originated from the original fluxes. However, uncertainties in weld appearance and element contents render it unjustified to reuse welding slags as fluxes. In the present study, a manganese-silicate flux has been demonstrated to be fully recyclable subject to submerged arc welding (SAW) for three times. The weld appearance is assessed against the initial weld metal (WM), while alloying element contents are evaluated according to AWS (American Welding Society) requirements. Flux composition and structure, two decisive factors affecting welding performance, are quantified. It is manifested that compositional changes mainly occur in the contents of MnO (39.50 to 34.66 wt pct), SiO 2 (38.46 to 34.25 wt pct), and Fe t O (1.55 to 6.78 wt pct). Moreover, crystalline structures of MgMnSiO 4 , and Mg 0.6 Mn 1.4 SiO 4 appear in the initially amorphous flux. The crystallinity is enhanced to 32.7 wt pct through flux recycling. Slight depolymerization is found in the amorphous structure, as the NBO/Si (non-bridging oxygens per silicon atom) is elevated by 0.2. Overall, this study demonstrates the capability of recycling welding fluxes and is poised to offer insight into further sustainable applications.