Óhreinindi og straumnýtni við rafgreiningu áls

„Óhreinindi og straumnýtni við rafgreiningu áls,“ er yfirskrift doktorsvarnar Rauan Meirbekova í Háskólanum í Reykjavík, sem fram fer 3. september kl. 14:00 í stofu V102.

Hér má lesa samantekt á ensku:

A typical aluminum smelter consists of multiple Hall-Heroult cells, requiring high investment costs for construction and operation. Furthermore, aluminum smelters are known to be heavy users of electrical energy. Therefore, it is important that the process is managed efficiently both for the aluminum industry and environmental issues. The cell parameter which describes how efficiently energy is used to produce aluminum is current efficiency. One of the factors which contributes to current efficiency loss is the presence of impurities.

The primary objective of this work is to contribute to the understanding of behavior of detrimental impurities such as phosphorus and sulfur in aluminum electrolysis and particularly their effect on current efficiency. Phosphorus is the most well-known example of an impurity which has negative effect on current efficiency. In the last few decades aluminum smelters have increased operating current density due to their focus on increasing productivity by increasing potline amperage. In this work, the effect of phosphorus on current efficiency was studied at higher current densities and at concentration levels which are present in electrolytes commonly used in the aluminum industry.

The second part of the study concentrates on behavior of the sulfur and its effect on the current efficiency. The decrease of the availability of low sulfur anodes has raised marked interest on whether there are any negative effects of increasing sulfur levels in anodes. The results conclude that both phosphorus and sulfur present detrimental effect on current efficiency in aluminum electrolysis and their effect is even more pronounced at lower concentrations of particular interest for the industry.