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Up to 10% of all metallic aluminum (Al) produced is lost due to dross generation during production. It also causes an environmental problem due to hazardous waste generation following treatment, as well as toxic gas generation when in contact with water/humidity. As a result, it is desirable to identify the parameters contributing to the generation of the Al white dross mixture. In view of this, a sampling procedure for collecting representative dross samples directly from the casthouse holding furnace has been developed together with a methodology for analyzing and evaluating the results. XRD was used for phase/chemical composition analyses of sieved dross samples, and both ring milling and cryomilling were used during sample preparation. Cryomilling proved to be the superior method allowing dross fractions < 1.25 and 1.25–4.5 mm to be pulverized. The fractions were analyzed and revealed that the sampling location inside the furnace plays a vital role as the injection of primary-produced Al into the furnace influences the dross characteristics. From Location 1 (closest to the injection point) to Location 4 (furthest away from the injection point), the metallic Al content in the dross decreased simultaneously as the oxide content increased. The results also confirmed that the larger size fraction had a higher metallic Al concentration, which correlates well with literature findings. By adopting a methodical sampling procedure followed by consistent routines for sample preparation, characterization, and analyses, process operations can be studied and thereby potentially used to minimize the loss of Al due to dross formation. Graphical Abstract

TEM EDS–EELS and XPS have been performed on disc samples of Al alloys 5182 (AlMg4.5Mn0.4) and 6016 (AlSi1.2Mg0.4) heat treated in an oxidizing atmosphere of 76 pct synthetic air, 20 pct Ar, and 4 pct CO2. For both alloys, an amorphous C–C bonded layer on top of a nanocrystalline MgO layer was observed, which is believed to inhibit further oxidation of Mg for the 5182 alloy and breakaway oxidation for the 6016 alloy.

+ 47) 404 76 828 Filtration of liquid aluminium is widely used in the industry for the removal of inclusions, and Ceramic Foam Filters (CFFs) are often the filtration media of choice. It is known that PH3 (phosphine) can be released from used phosphate bonded CFFs when in contact with water. Additionally, there is a need of an improved understanding of the thermal stability and the chemical reactivity of these types of filters, as there is limited information available in the public domain.In the present preliminary study, three CFFs, i.e. Substrate 1-3, with varying AlPO4 (aluminium phosphate) content were studied under controlled conditions. Samples of the substrates, as produced and in contact with 5N pure aluminium, were heat-treated in a vacuum induction furnace at 850 °C and 1300 °C, as well as thermally studied at 850 °C using a Differential Scanning Colorimeter connected to a Thermogravimetric Analyser (DSC-TG). All tests were performed under an inert atmosphere of argon (Ar). Mass changes of ~0.001 % were registered for the pure substrates, and 0.003-0.10 % when in contact with aluminium. In the latter case, diffusion of P (phosphorous) from the bulk of the substrate to the interface was established to have taken place. A colour change, from white to orange/brown, was also observed at the interface, which is a clear sign that a chemical reaction has taken place. As a result, the thermal stability of the substrates can be questioned under present conditions.

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