ADVANCED MATERIALS & PROCESSES | NOVEMBER/DECEMBER 2024 28 circular economy principles. By reusing spilled-out metal powders, companies can significantly cut down on the amount of waste that would otherwise end up in landfills[12]. This not only conserves resources but also reduces the environmental footprint of manufacturing processes. Resource Efficiency. Maximizing the use of all available material enhances overall resource efficiency in production processes. This approach aligns with the principles of a circular economy, where the focus is on minimizing waste and making the most of available resources. In the case of metal powders, this means ensuring that every particle is utilized to its fullest potential. CHALLENGES IN REUSING METAL POWDERS Recycling metal powder, particularly for critical applications such as hybrid mining tools, requires a meticulous process to ensure the quality and performance of the final product. Despite the clear benefits, the reuse of metal powders is not without challenges[7,10,11]: Contamination. Ensuring that the reclaimed powder is free from contaminants is crucial. Contaminants can significantly affect the quality and performance of the final product. Consistency. Achieving a uniform particle size distribution and consistent chemical composition in reclaimed powders can be challenging but is necessary for maintaining product quality. Processing Costs. While reusing powders can save on raw material costs, the processes involved in cleaning, screening, and analyzing the powder can add to the overall cost. FUTURE DIRECTIONS IN SUSTAINABLE POWDER REUSE The development of advanced recycling technologies will further enhance the feasibility of reusing metal powders[9]. Techniques such as laser sintering and advanced sieving methods can improve the quality and consistency of reclaimed powders, making them suitable for even more demanding applications. were conducted and compared against unused powders. Here are some key findings: Chemical Composition. The chemical analysis revealed that the reclaimed NiCrBSi-WC mixture, with an additional 10% NiCr powder, maintained its original composition of 60% WC and 40% NiCr[1] with negligible deviations as shown in Table 1. This consistency is crucial for ensuring the material’s performance in harsh mining environments. The chemical analysis was conducted using atomic absorption spectroscopy. Microstructure Evaluation. Micro- structural analysis revealed distinct differences between the reclaimed and unused powders. The unused powders exhibited a more uniform grain structure with well-defined boundaries, indicative of their pristine condition[3,8] (Fig. 2a). In contrast, the reclaimed powders[3] displayed a mixed grain structure with some evidence of particle agglomeration and minor inclusions and porosity as shown in Fig. 2b. Mechanical Properties. Hardness tests revealed that, in comparison to samples made from unused powder, the samples only showed a 30 to 40 HV drop in hardness on base mixture NiCrSi and 300 to 500 HV decrease on WC particles[7,10] shown in Table 2. Wear resistance testing verified that the hybrid tools showed outstanding endurance under simulated mining settings, even with this small reduction. BENEFITS OF REUSING METAL POWDER The reuse of spilled-out NiCrBSi powder not only aligns with sustainable manufacturing practices but also offers several tangible benefits[4-6,12]: Cost Savings. By reclaiming and reusing spilled powder, manufacturers can significantly reduce raw material costs. This is particularly beneficial in industries like mining, where tools and components need to be replaced frequently due to wear and tear. Environmental Impact. Reducing waste contributes to lower environmental pollution and supports TABLE 1 — CHEMICAL ANALYSIS OF THE POWDERS Unused powders Used powders WC 50-60% 40-60% Fe 3-4% 3% Cr 10-18% 9-15% Si 1-3% 2-3% B 0.8-1.2% 0.7-0.9% Ni 60-90% 70-80% Fig. 2 — Micrographs of (a) unused powder and (b) reused powder. (a) (b) TABLE 2 — HARDNESS VALUES FROM TWO SAMPLES TAKEN IN MULTIPLE LOCATIONS Unused powder, HV Reused powder, HV 889 823 926 865 910 905 870 873 890 865
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