Sampling Procedure, Characterization, and Quantitative Analyses of Industrial Aluminum White Dross

Abstract

AbstractUp 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