Morten Sørlie

Formation of gas complexes between europium chloride and aluminium chloride above liquid chloroaluminate mixtures

Abstract Gas complexes above liquid mixtures of EuCl2 and AlCl3 were studied spectrophotometrically making use of the 5d ← 4f transition in Eu2+. The pressure of Eu2+-complexes above the molten mixtures can be described by the relation P Eu-Al-Cl = (P Al 2 Cl 6 ) exp 10 4.048− 4810 T +P Al 2 Cl 6 exp 10 1.314− 3023 T in the range 0.05

Ramming Paste Related Failures in Cathode Linings

Some common failures that may be introduced into the rammed parts of cathodes during installation, preheating or early operation are discussed. Most emphasis has been put upon the shrinkage behaviour of ramming pastes during baking and upon crushing of aggregate particles during ramming. Incomplete knowledge of such materials properties may lead to early failure of electrolysis cells.

Solubility of antimony metal in molten antimony(III) chloride-aluminum chloride and antimony(III) chloride-cesium chloride mixtures☆

Abstract The solubility of antimony metal in molten SbCl3AlCl3 and SbCl3CsCl is reported. Measurements were made at many compositions and temperatures within the following ranges: SbCl3AlCl3 system, 1–90 mol% AlCl3 at 235–430°C; SbCl3CsCl system, 0.5–25 mol % CsCl at 405°C, 45–80 mol % CsCl at 628°C and 60 mol % CsCl at 562–642°C. The solubility is attributed to the reversible reaction of antimony metal with antimony(III) in the melts to form two types of species with oxidation states below 3+. One type is stabilized in SbCl3AlCl3 melts at high pCl (pCl = − log[Cl−]) and the other is stabilized in SbCl3CsCl melts with low pCl. Both types are present in melts with a high concentration of SbCl3, but it is in such melts that antimony metal has its lowest solubility.

Property Changes of Cathode Lining Materials during Cell Operation

Carbon cathode materials are catalytically graphitized during the aluminium electrolysis. The graphitization has been characterized by X-ray diffraction. The graphitization and salt penetration cause profound changes in electrical and thermal conductivities. These properties have been determined for different commercial cathode materials as function of operational time and temperature. The assumed correlation between electrical and thermal conductivity is found to be poor. The changes in thermal conductivities of refractory and insulation materials have also been determined and actual examples of cell deterioration are given. Heat balance calculations based on the changing values of electrical and thermal conductivities demonstrate drastic changes as the cell get older. Calculations based only on virgin materials properties will give quite erroneous results.

Densification of Ramming Paste in Cathodes

Cold type carbonaceous ramming mixes are now used for refractory purposes in several metallurgical and electro-metallurgical industries. Green density measurements of these pastes are easily performed on the spot during and after installation, by using a simple impact penetrometer. Used in the cathode repair shop, it serves as a quality assurance tool with respect to improved density, compaction uniformity and installation procedure of the rammed parts. Four commercial room temperature ramming pastes, differing widely in quality and compaction characteristics, have been used in this work. Penetrometer measurements during relining of cathodes have established optimal installation practices for the various pastes.

Penetration of Sodium and Bath Constituents into Cathode Carbon Materials Used in Industrial Cells

To elucidate further upon possible mechanisms of reaction leading to a shortened life-time of the carbon lining in aluminium reduction cells, two commercially available cold type seam mixes have been tested with respect to penetration of sodium and bath constituents into the material. Testing conditions were kept close to what may be expected in the cathodic part of industrial cells in operation. The Type I seam mix consisted of anthracite with a substantial amount of graphitic material and a binder which during baking gave a soft, porous coke. The Type II was an amorphous anthracite mix with an aromatic binder giving a high crushing strength coke during baking.