Analysis of the technology of electrochemical production of zirconium

Abstract

To date, reactor-grade zircon is produced on an industrial scale using metallothermic and electrochemical methods. Electrolytic production of reactor-purity zirconium in a sealed electrolyzer is more cost-effective than metallothermic production, as it does not require iodide refining and the use of reducing metals (Na, Mg, and Ca). Despite the importance of this production, its features are not fully described in the literature. This study presents the results of industrial tests of the electrolysis process in a sealed electrolyzer with a current load of 10 kA from the molten electrolyte KCl–KF–K2ZrF6. Based on the achieved technological indicators, the current efficiencies of the main cathode and anode reactions were determined and the factors influencing them were evaluated. We analyzed the composition of nutrient salts and the mechanism of accumulation of potassium fluoride in the electrolyte, an increase in which concentration leads to an anode-destroying effect. We considered possible mechanisms of the electrochemical formation of freons and compiled material balances for all starting substances and reaction products. The change in the electrolyte density during electrolysis was calculated, which allowed justifying the volume of its daily drainage. Fine carbon and zirconium powder formed in the electrolyte due to the interaction with potassium metal are not separated and are removed for chemical redistribution, which reduces the productivity of the electrolysis process.