Analytical Modeling of Current and Potential Distribution over Carbon and Low-Consumable Anodes during Aluminum Reduction Process

Abstract

Based on the theory of current and potential distribution for aqueous solution systems and existing analytical models, tertiary current and potential distributions over carbon and non-consumable anodes in cryolite-alumina melt are calculated. The influence of resulting distribution pattern and the values of local current density and local anode potential on anode process stability together with related probable causes of the increased consumption of carbon and non-consumable anodes are discussed. The main factors influencing current and potential distribution are anode overpotential and diffusion layer thickness, which represents the electrolyte properties related to electrolyte mixing conditions. Local current density on the edges of a rectangular anode is 2 times higher than in the central part. Current distribution over rough anode surface is uneven – local current density at peaks of surface defects is higher by 40 to 60 %. The theoretically established relationship between the anode surface structure and current and potential distribution could be the primary cause for increased anode consumption and passivation with subsequent destabilization of electrolysis in standard and low-melting electrolytes. The possible ways to equalize the current and potential distribution across the anode surface are presented.

The Physicochemical Basis for the Production of Rapeseed Oil Fatty Acid Esters in a Plug Flow Reactor

“…It is generally known that under the current conditions, the production and promotion of fatty acid esters depends largely on subsidies and the policies of the states [32][33][34][35]. Subsidization can be explained by high competition with the petroleum fuel market and the complexity of the process of obtaining pure fatty acid esters [36][37][38], which affects their production cost [39][40][41].…”

Effects of alumina on the stability of ferrite–calcium sinter with dicalcium silicate

“…In this case sinter should have sufficient strength and stability to scattering, what is provided by sinter stability after its complete assimilation of calcium oxide. Forming of new phases, having the strengthening effect of the system in general, is possible during structure forming [16][17][18]. Thereby examination of Al 2 O 3 influence on stability of ferrite-calcium sinter, which contains Ca 2 SiO 4 , is considered as a priority task of this research.…”