Lanthanum-Light Metal Alloys Production Using Secondary Resources—Thermodynamic Analysis

Abstract

Rare-earth-elements (REE) can be used as alloying agents to improve the properties of aluminum alloys. REE are often added in the metallic form to produce the alloys, but the high cost of REE metals makes the alloys expensive thus limiting their application. An alternative way to make REE-Al alloys is by reacting REE oxides with light metals. For this route, secondary light-metal resources, such as aluminum dross, have the potential to be used to reduce the cost of alloy production and at the same time limit waste generation. In this study, a systematic thermodynamic evaluation of aluminum-lanthanum (Al-La) alloy production using lanthanum oxide (La2O3) and different light-metal secondary resources was carried out. Three different Al dross compositions were evaluated, each with different metal/metal oxide ratios. Based on the analysis, Al dross can successfully be used as the starting material for this process. The La2O3 (10 wt% of total charge) was completely reduced in all simulated compositions. Additional calculations were carried out to simulate a process in a Rotary Salt Furnace (RSF). From this analysis, the use of chloride salts is predicted to only slightly reduce the yield, but the use of fluoride salts should be avoided.