Utilization of industrial waste metal alloy powder as fuel

Metal powders including aluminum, iron and metal alloys have been considered as a fuel for energy generation without releasing carbon dioxide and being recyclable. While additive manufacturing processes desire feedstock microparticles with a specific size range, a significant amount of metallic powders is left in its waste stream. In this work to investigate the potential applications of these alloy powders, they are mixed with solid metal oxide particles for combustion tests in ambient and low-pressure environments. The thermochemical properties and exothermic characteristics are measured on the mixtures of micro-sized AlSi10Mg particles with a median diameter of 13 µm and CuO nanoparticles of 500 nm. Experimental results indicate, compared to Al micron particles with a similar average diameter, the reaction between AlSi10Mg powder and oxygen shows a comparable onset temperature (around 1000⁰C), a similar activation energy (316.9 kJ/mol), but a much higher energy release (11.5 kJ/g vs. 4.2 kJ/g). When mixed with CuO nanoparticles, AlSi10Mg/CuO and Al/CuO mixtures exhibit a similar reaction kinetics which is characterized by the diffusion of gaseous oxygen produced from the thermal decomposition of CuO. In the ambient combustion tests, the AlSi10Mg/CuO powder shows a 20 % shorter ignition delay, 3 times faster burning rate, and up to 2 times higher impulse than these of the Al/CuO powder. When a low air pressure (about 100 Pa) is applied, the AlSi10Mg/CuO powder is successfully ignited and combusted, while the micron-Al/CuO powder cannot be ignited. We conclude the micro-sized Al-Si-Mg alloy particles recycled from the advanced manufacturing processes can be a good candidate for metal fuel.