Production of Copper Ingots from Industrial Waste: An Innovative Solid-State Sintering Process with Microstructural and Crystallographic Analysis

Abstract: This study investigates the recycling of industrial waste copper chips generated during the processing of copper chips containing approximately 5% magnesium. An innovative patented modification was integrated with the classical solid-state sintering method to directly produce copper ingots from these wastes. Unlike conventional powder metallurgy techniques, the process employs a low-pressure (7 bar) and short-term (5 minute) sintering step without prior surface cleaning. Initially, the chips undergo pre-compression at 200°C, followed by heat treatment at 1035°C, and subsequently a secondary pressing to yield copper ingots. X-ray diffraction analysis predominantly identified the face-centered cubic copper phase, while energy dispersive spectroscopy indicated only trace amounts of oxygen and iron. The abbreviated sintering duration successfully preserved over 97% of the metallic copper phase and minimized oxide formation. Scanning electron microscopy confirmed a homogeneous microstructure, with crystallite sizes and morphology optimized based on the sintering conditions. This approach offers substantial advantages in terms of energy savings, production efficiency, and environmental sustainability.