Electrolytic Refining of Aluminum

Abstract—An electrolyte of the composition 220 g NaCl, 280 g KCl, and 60 g AlCl₃ is studied to check a possibility of using it for the refining of crude aluminum and aluminum scraps in a chloride electrolyte and achieving a melting point of the melt in a range of 700–750°C during electrolytic metal refining. The electrolyte is tested on a laboratory setup consisted of a Nabertherm furnace, an M381 voltmeter for measuring voltage, a TRM500 thermoregulator for measuring temperature, a V-24 rectifier for dc supply, and a laboratory cell. The main units of the laboratory cell are two corundum beakers of different sizes, an anodic current lead (Mo in a corundum case), and a cathodic steel rod with a graphite tip, the initial anodic alloy, and an electrolyte. The experiment is carried out at 707–726°C for 180 min using a current of 6–6.5 A and a voltage of 2.5–3.5 V. The weight of refined aluminum is 5.825 g, and the current efficiency is 92.5%. The electric energy consumption is 10.86 W h g^–1. The obtained results confirm that the method can be used for the refining of crude aluminum and aluminum scraps to produce high-purity aluminum.