ALUMINUM PRODUCTION USING HIGH-TEMPERATURE SOLAR PROCESS HEAT

Abstract

The primary metals industry is one of the most energy intensive in the manufacturing sector, and is consequently also a major source of climate-altering gases. The replacement of electrolysis or electrothermal processes with direct reduction processes using high-temperature solar process heat may well be economical, especially when the costs of CO 2 emission are included in the analysis. In particular, aluminum production by carbothermal reduction is a very high-temperature, energy-intensive process. The temperature required, in the range 2300–2500 K, is too high for practical process heat addition from combustion sources alone. Only electric-arc furnaces or highly concentrated solar are capable of supplying process heat at these high temperatures. 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 intermediate AlN compound are proposed for study and demonstration projects for alternative solar-thermal processes to replace the Hall–Héroult process.