Numerical simulation of copper recovery from converter slags by the utilisation of spent potlining (SPL) from aluminium electrolytic cells

Abstract

An innovative method was devised to improve copper recovery and operational efficiency of the Cu converter slag-cleaning furnace, by utilising both carbon and fluoride values of an otherwise environmental hazardous material (i.e. spent potlining (SPL)) produced from the aluminium industry. Results based on numerical modelling show that 90% Cu recovery could be achieved by adding as little as 3-4 wt-% of SPL to the molten converter slag. The fluorides and sodiumcontaining compounds in the SPL reduced the slag viscosity, resulting in a much faster settling rate of matte droplets. In this process, the SPL could be detoxified by destroying the cyanides to form harmless N 2 gas, and inertising the fluorides in a much diluted form in the ferro-silicate slag, ensuring a safe disposal to the environment.On a conçu une méthode innovatrice pour améliorer la récupération du cuivre et le rendement opérationnel du four de nettoyage de la scorie du convertisseur de Cu, en utilisant tant la teneur en carbone que la teneur en fluorure d'un matériau autrement dangereux sur le plan environnemental (c'est-à-dire le SPL) produit par l'industrie de l'aluminium. Les résultats basés sur la modélisation numérique montrent qu'on pourrait obtenir une récupération de 90% du Cu en ajoutant aussi peu que 3 à 4% en poids de SPL à la scorie fondue du convertisseur. Les fluorures et les composés contenant du sodium dans le SPL réduisent la viscosité de la scorie, ayant pour résultat une vitesse de déposition plus rapide des gouttelettes de matte. Avec ce procédé, on peut désintoxiquer le SPL en détruisant les cyanures pour former du gaz inoffensif de N 2 et en rendant les fluorures inertes dans une forme bien diluée dans la scorie de ferrosilicate, assurant ainsi une élimination sécuritaire pour l'environnement.

Deactivation Influence of HF on the V2O5–WO3–TiO2 SCR Catalyst

“…3 The watersoluble F − in the waste discharged from the electrolytic aluminum industry is about 2000 mg L −1 , which is obtained through the standard leaching procedure. 4,5 It greatly exceeds the limitation (F − < 100 mg L −1 ) of the Chinese national standard (Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity, GB 5085. . 5 Therefore, it is important to achieve the harmless treatment of electrolytic aluminum waste.…”

“…4,5 It greatly exceeds the limitation (F − < 100 mg L −1 ) of the Chinese national standard (Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity, GB 5085. . 5 Therefore, it is important to achieve the harmless treatment of electrolytic aluminum waste.…”

“…Many schemes have been applied for the treatment of electrolytic aluminum waste. The waste can be used as an additive in the Cu converter slag-cleaning furnace for copper recovery or as the secondary raw material and fuel at the cement plant for economic benefits . To destroy cyanides, the waste can be treated by oxidation at medium (500–850 °C) or high (1100–1300 °C) temperatures .…”

“…Because the waste has a high carbon content (as high as 58.56%), co-firing it with coal in boilers could recover the carbon heat and save the coal consumption. Attributed to the high furnace temperature, cyanides in the waste would be destroyed to form harmless N 2 gas . Some fluorides would vaporize and transform into HF with the presence of water vapor in the flue gas, while the others would stay with the coal ash in a more diluted form .…”

“…Attributed to the high furnace temperature, cyanides in the waste would be destroyed to form harmless N 2 gas . Some fluorides would vaporize and transform into HF with the presence of water vapor in the flue gas, while the others would stay with the coal ash in a more diluted form . The released HF could be easily removed by Ca­(OH) 2 solution in the wet flue gas desulfurization (WFGD) tower.…”