Aluminum production using high-temperature solar process heat

The primary metals industry is one of the most energy intensive in the manu facturing sector, and is consequently also a major source of climate-alteri ng gases. The replacement of electrolysis or electrothermal processes with direct reduction processes using high-temperature solar process heat may we ll be economical, especially when the costs of CO, emission are included in the analysis. Ln particular. aluminum production by carbothermal reduction is a very high-temperature, energy-intensive process. The temperature requ ired, in the range 2300-2500 K, is too high for practical process heat addi tion from combustion sources alone. Only electric-are furnaces or highly co ncentrated solar are capable of supplying process heat at these high temper atures. The aluminum industry presents unique opportunities for industrial implementation of solar process heat. Use of high-temperature solar process heat can drastically reduce the emission of climate-altering gases, reduce the reliance on electricity, and make possible a direct thermal route from the ore to metal. Two industrially-researched direct aluminum or aluminum- silicon alloy producing processes, and one process that forms an intermedia te AlN compound are proposed for study and demonstration projects for alter native solar-thermal processes to replace the Hall-Heroult process. (C) 199 9 Elsevier Science Ltd. All rights reserved.