ORALS

Aluminum dross consists of a heterogeneous mixture of large lumps, fine oxides and metal pieces. Consequently, sampling requires considerable experience and effort. Additionally, the skimming procedure of the melt, the alloy composition, the type of fluxing agent, and the cooling method of the scum all control the amount of free-metal present in the dross [1]. In industrial practice, the formed dross in the Al-smelter is regularly removed and a part of the liquid metal can be squeezed out. Subsequently, the tilting drum furnace recovers most of the aluminum from the scum with the assistance of a crumbly salt slag [2]. Of significant interest is the recovery of the largest possible amount of metallic Al from the dross during the production process by using a dross press. The aim of this work is to compare the press system currently available at an Austrian Al-smelter with a rented dross press. First, an optimized time-distance diagram for the hired press is determined. Thereafter, the masses of recovered metallic Al are recorded for a period of one week. A part of the resulting hot scum of every charge is processed with the existing press, the other part is processed with the rented. As a result, the proportion of recovered Al based on the total amount of dross is determined for both press systems. Furthermore, a comparison in terms of geometry of the press head, economy and appearance of the dross compacts is carried out. The results are of great importance to the Al-processing company as the optimization of the recycling process depends on a higher aluminum output [3, 4].

References:
[1] Manfredi O., Wuth W. and I. Bohlinger: Characterizing the Physical and Chemical Properties of Aluminum Dross. JOM (1997), 48-51.
[2] Krone K.: Aluminiumrecycling: Vom Vorstoff bis zur fertigen Legierung, Aluminium-Verlag, Duesseldorf (2000).
[3] Roth D. J.: History and future of dross processing. Light Metals (2015), 1005-1009.
[4] Perry O. H.: The development of the modern dross press. Light Metals (2000), 675-678.