Salt flux treatment of molten aluminium is common practice in aluminium production and recycling used to decrease oxidation and metal losses and to clean the metal. The most common class of fluxes contain a mixture of sodium chloride and potassium chloride, and minor amounts of fluoride compounds. Fluxes are specified to certain chemical compositions to produce defined process petameters, such as melting point, surface activity and refining efficiency. Thus, salt flux composition directly affects both the efficiency of the treatment operation and the final product quality.

As metal quality standards grow more demanding, it is necessary to measure the composition of delivered flux and verify that the blend matches the desired specifications. X-ray diffraction (XRD) and X-ray fluorescence (XRF) are the most suitable methods to do this in laboratory. However, in most cases the analysis is made using semiquantitative pre-calibrated programs, which does not assure the accuracy required by the industrial production. This is because neither certified reference materials nor suitable measurement techniques had been available. This paper describes a comprehensive XRD-XRF system for measuring the entire phase and elemental flux composition from major compounds to minor impurities. First, we developed and certified 14 reference materials as National or Branch Measurement Standards. Then certified measurement techniques were developed to measure main flux compounds including NaCl, KCl, AlF3, Na2SiF6, K2SiF6 and Na3AlF6. Finally, we complimented the certified measurement techniques with reference-free options and formulated the methodology of how to apply them in combination to fully characterize the flux composition. In addition, the paper gives examples of industrial fluxes analyses.

Aluminium smelter casthouse (CH), operates at approximately 800 °C, generates heat (furnace burners and incoming hot aluminum molten metal from reduction) that have a lot of opportunities to conserve and reuse it to support sustainability and carbon footprint. It helps the reduction and consumption of gas/fuels and other consumable materials.

This paper focuses on advanced technology and approaches to overcome challenges to conserve, reduce and reuse energy and materials in casthouses. In normal process this heat energy is exhausted through stacks. Normally, 0.6 tonne (t) per annum capacity smelter casthouse wastes around 35 MJ/s of energy (reaches to 135 MJ/s at peak operation) considering 30% maximum thermal efficiency of the casthouse. This energy could be reused for launder preheating and could also be extended further to other preheating opportunity e.g., scrap, casting molds, tools preheating, etc. Moreover, preventing loss of heat of molten metal flowing through launders not only conserve energy but help in quality of casting value added and other products.

Lean technology concepts of conserving and reusing energy should replace the conventional complex system during operation within facilities. It helps optimizing quantity and design of equipment and systems in casthouses. Energy potential in aluminium casthouse is well known and efforts are underway worldwide to optimize it. This paper put further emphasis to use technology and continual effort in the direction to commercialise concepts to conserve energy to support sustainability and reduce carbon footprint.

Energy supplies have always been a premium commodity that greatly affect the operating viability of our plants, now more than ever our processes must reduce exposure to the ever-increasing costs associated with energy usage. This is a complicated scenario as we also have a need to use energy more cleanly to comply with the latest environmental legislation. The cast house is no exception to optimised efficiency demands, the big question is, how do we maintain high-performance cast houses while reducing the energy we use and can this be done while respecting a need to reduce the emissions from cast house equipment. In this paper Mechatherm will share its experiences in addressing these issues, including our recent experience in replacing a traditional natural gas combustion system with a hydrogen fuelled burner system. What are the challenges faced in implementing such projects? do the results meet the efficiency and environmental challenge?

The Treatment of Aluminium in Crucible (TAC) process, integrated to sodium reduction skimming stations in Emirates Global Aluminium (EGA) Al Taweelah smelter, consists essentially in the addition of aluminium fluoride (AlF3) to the molten metal during the first seconds of agitation and resulting in removal of alkali metal components through the formation of stable fluoride compound. This entire operation is to reduce aluminium oxidation and avoiding factors that could impact the performance of the final aluminium products. Despite its effectiveness, this process incurs substantial costs, due to the consumption of AlF3 and TAC rotors. The continuous recirculation of AlF3 particles in the molten metal induces erosion and abrasion on the TAC rotor, that necessitates frequent replacement and escalating maintenance and spare costs. In 2021, 861 t of high bulk density AlF3 costing 4.9 MUSD were consumed. The use of high density AlF3 with sharp and abrasive crystal faced particles for metal treatment leads to micro-cutting and more severe erosion and abrasion resulting in higher consumption of rotors. Comparing to low bulk density AlF3 with rounded shape particles, micro-ploughing and built-up wedges were mainly observed. This leads to lower erosion and abrasion of the rotor surface. This paper proposes the optimization of TAC operation to achieve the required metal quality and process efficiency, while reducing the cost associated with AlF3 and TAC rotors consumption. Consequently, it is proposed substituting high bulk density AlF3 with low bulk density AlF3 for molten metal treatment. This change aimed to reduce erosion and abrasion on the TAC rotor, thereby prolonging its lifespan and reducing operational costs. Indeed, the implementation of low bulk density AlF3 yielded to promising results by achieving a remarkable 39 % reduction in AlF3 consumption, as compared to the initial target of 20 %, with operating life greater than 600 cycles per rotor. This represents a substantial reduction of 54 % in rotor consumption. These improvements not only enhanced process efficiency but also generated significant and validated savings of approximately 0.6 MUSD.