Cleaner Engineering and Technology (Feb 2022)
Criticality assessment of metal resources for light-emitting diode (LED) production – A case study in China
Abstract
Understanding the importance of raw materials is crucial for ensuring high material efficiency in industrial production processes. A common criticality assessment of resources is usually a top view on their supply risk and economic importance. This cannot directly be integrated in a specific process for material manufacturing, which is in high demand to identify the importance of a resource for the process and implement process optimization. In this study, a parameter named resource recirculation factor is introduced, and the criticality assessment model is reformed to facilitate the evaluation of the LED production process from substrate preparation to lamp manufacture. 22 types of materials were selected for evaluation with material flow analysis. The criticalities of gallium and indium, with values of 159.33 and 24.18, were found to be the largest owning to their high supply risk and environmental risk values, which were significantly higher than those of the other materials, such as copper (0.01) and iron (0.27). The high criticality of gallium resulting in trimethyl gallium being the most important material, while trimethyl indium and indium tin oxide (ITO) etchant ranked second and third, respectively. Based on the comparison of the production sections, the epitaxial growth and chip fabrication compressed the two most important sections, which were closely related to the critical metals. Under comprehensive environmental evaluation, the environmental impact of LED production sections was in the order of chip fabrication > substrate preparation > lamp manufacture. The proposed criticality assessment method can provide a basis for the material evaluation and cleaner production of industrial production processes, where comprehensive environmental evaluation can also contribute to the criticality evaluation.
