Plasma-induced melting and microfiber formation from zeolite-containing mineral waste

The zeolite-containing waste generated during the petroleum fluid catalytic cracking (FCC) process is a high-volume aluminosilicate by-product and a potentially valuable secondary raw material. When these residues lose their catalytic performance, they become environmentally problematic, rendering them unusable and unreusable. This problem creates a clear need for advanced high-temperature mineral processing methods, with plasma technologies offering a particularly promising option. This work investigates the transformation behaviour of zeolite waste under atmospheric-pressure plasma conditions, focusing on melt formation, structural changes, and the development of continuous aluminosilicate microfibers. Dried and sieved zeolite waste particles (60 µm size) were injected into an atmospheric-pressure direct current (DC) air plasma jet. The temperature of the plasma jet exceeded 3500 K and facilitated the rapid melting of zeolite particles. The molten droplets were aerodynamically stretched within the plasma jet to form microfibres with diameters in the 0.1–5 µm range. Scanning electron microscopy (SEM) revealed a smooth fiber morphology without unmelted inclusions, while X-ray diffraction (XRD) confirmed complete vitrification and the absence of characteristic zeolite-Y diffraction peaks. Analysis of the plasma jet parameters showed that plasma enthalpy, gas flow regime, and reactor geometry strongly influence melt homogeneity and fiber formation efficiency. These findings show that atmospheric-pressure plasma processing can effectively convert zeolite waste into high-quality aluminosilicate microfibers, providing an effective way to convert mineral waste into useful products.