Alumina Solubility and Electrical Conductivity in Potassium Cryolites with Low Cryolite Ratio

The kinetics of the cathode process on tungsten in KF-AlF 3-Al 2 O 3 melts and suspensions was studied by means of voltammetry and galvanostatic polarization. The effects of the temperature, [KF]/[AlF 3 ] ratio, Al 2 O 3 content on the kinetic parameters of electrowinning of aluminum from the KF-AlF 3-Al 2 O 3 melts and suspensions were determined. Introducing Al 2 O 3 slurry into the suspension and increasing its proportion make the diffusion of the electroactive ions to the cathode more difficult. The parameters for the suspension electrolysis were chosen on the basis of electrochemical measurements. The possibility of aluminum production during the electrolysis of KF-AlF 3-Al 2 O 3 suspension with 45 wt% Al 2 O 3 in the solid phase was demonstrated.

supporting

confidence: 63%

Section: °Cmentioning

confidence: 99%

Cathode Process at the Electrolysis of KF-AlF₃-Al₂O₃Melts and Suspensions

Nikolaev

Suzdaltsev

Polyakov

et al. 2017

“…Apisarov et al 16 described the temperature dependence of the electrical conductivity in the electrolytes with additions of Al 2 O 3 and LiF published in his previous paper 15 by the linear equation. The subsequent paper 17 summarized the above mentioned results, only.…”

mentioning

confidence: 98%

Electrical Conductivity of Low-Temperature Potassium Cryolite Electrolytes Suitable for Innovation of Aluminum Preparation

Kubiňáková

Danielik

Hı́veš

2018

Innovations of aluminum electrolysis process are focused on the inert electrodes and the new types of electrolytes with lower temperature of primary crystallization. The main component in new types of molten systems can be a potassium cryolite. Advantages of these electrolytes are low possible working temperature (above 660 • C) and sufficient solubility of an electrochemical active compound (alumina) at these temperatures. The electrical conductivity is one of the most important properties of the electrolytes. Electrochemical impedance spectroscopy was used as a suitable measurement method for determination of the electrical conductivity. Potassium cryolite-based mixtures with the different molar ratios (molar ratio of KF and AlF 3 ) and with various additives were studied as a function of the temperature. The molar ratio of binary melt KF-AlF 3 varied from 1.2 to 1.5 with the step of 0.1. The temperature dependence (from 655 • C to 850 • C) and the influence of the addition of Al 2 O 3 , CaF 2 , MgF 2 and LiF on the electrical conductivity were obtained. The electrical conductivity was measured by tube-type cell with stationary electrodes; AC-techniques with a sine wave signal in the high frequency range were applied. Temperature and concentration dependencies of conductivity in the studied systems were described by non-linear regression equation.

“…It can be seen that the solubility increases with temperature and CR values. 95,96 KF-NaF-AlF 3 −based melts have advantages such as good alumina solubility of potassium cryolite and better electrical conductivity of sodium cryolite. The solubility of alumina decreases when the Na + cations replace K + in the KF-NaF-AlF 3 system.…”

Section: Low-temperature Electrolytesmentioning

confidence: 99%

Review—Primary Production of Aluminium with Oxygen Evolving Anodes

Padamata

Singh

Haarberg

et al. 2023

Due to environmental and economic concerns, carbon-free aluminium production has been an ultimate goal for aluminium industries. For the past few decades, a considerable amount of research has been conducted to find an inert anode material that could replace the consumable carbon anodes for aluminium electrolysis. Anodic materials such as metals, ceramics, and cermets have been studied extensively. All these anode materials have their advantages and disadvantages. However, metal alloys have proven effective because of their resistance to high-temperature corrosion and their ability to produce a protective oxide layer. For a successful adaptation of metallic anodes into the aluminium electrolysis cell, an electrolyte with a low operating temperature and high alumina solubility with good electrical conductivity is required. A wettable cathode with a shorter anode-to-cathode distance is preferred to compete with the Hall-Héroult process in terms of energy requirements. This review discusses the research progress on inert anodes, wettable cathodes, and electrolytes.