Hazard evaluation, explosion risk, and thermal behaviour of magnesium- aluminium alloys during the polishing process by using a 20-L apparatus, MIEA, and TGA

Abstract Magnesium-aluminium alloy powders, although widely used in the polishing process on variable scales, also have a potential to be explosive. Having a thorough understanding of the thermal aspects of magnesium-aluminium alloy powder ensures process safety and is essential for developing an adequate emergency system. This study analysed the influence of the particle size, ranging between 105 and 420 μm on the thermal characteristics of magnesium-aluminium. The results revealed that at a dust concentration of 1750 g/m3, 105, 210, and 420 μm magnesium-aluminium alloy powders exhibited a maximum explosion pressure of 0.97, 0.86, and 0.78 MPa, respectively. The limiting oxygen concentration values of 105, 210, and 420 μm samples were 4, 13, and 15 vol.%, respectively. The apparent activation energies Ea of 105, 210, and 420 μm samples were 286.5–70.6, 165.2–39.9, and 224.8–168.8 kJ/mol, respectively. Furthermore, the flammability parameters exhibited greater reactivity for smaller particle sizes, i.e., the minimum ignition temperature sharply decreased from 700 to 550 °C. Thus, this study provides valuable insights into the combustion characteristics and the severity of the dust explosion hazards of magnesium-aluminium alloy powders in order to ensure better safety standards in the metal processing industry.