Chemisch-mineralogische Beschreibung von Gießpfannenschlacke der voestalpine Stahl Linz GmbH

Research output: ThesisMaster's Thesis


In the course of this work, 5 ladle slag samples from the process route of the blast furnace are chemical-mineralogical characterized. Since ladle slag is a decomposition slag due to the modification transformation from ß-dicalcium silicate to ¿-dicalcium silicate and the associated increase in volume, the effect of the cooling time of batch-pure dumped slag on the elution of environmentally relevant elements as well as the possibility of improved slag handling was also of great interest. In the course of these conditioning tests, the slag types "ultra-low carbon" (ULC) and "sour gas" (SG) were sampled, which were dumped in liquid form or covered and set aside for slow cooling. Furthermore, the material of the ladle slag was separated into three grain sizes using a mobile sieving aggregate to investigate the possibilities of chemical or even mineralogical sorting with simple industrial processing steps. Analysis by X-ray diffraction of the ladle slag samples identified the phases of dicalcium silicate, hydrogarnet, phases of the melilite group, mayenite, periclase, tricalcium aluminate and quartz. The mineral stock could be extended with the electron beam microprobe point analyses by spinel, wuestite, brucite, aluminum hydroxide, portlandite, perovskite, and metallic iron granules. The different chemical composition of the conditioning samples concerning CaO and FeO (+ MnO & Cr2O3) is also reflected in the phase composition. Thus, the FeO-rich and CaO-poor ULC slag consist mainly of spinel and wuestite embedded in a matrix of mayenite and sporadic dicalcium silicate grains. On the other hand, the CaO-rich and FeO-poor sour gas slag consists primarily of tricalcium aluminate, mayenite and discretely distributed dicalcium silicate. For environmental testing, all samples were prepared with ultrapure water at a liquid/solid ratio of 1/10 according to ÖNORM EN 12457-4:2003-01 and eluted for 24 h in an overhead shaker. To gain a better understanding of the elution controlling mechanisms, a pH-dependent eluate was prepared, and its results were subsequently hydrogeochemical modelled using LEACHXS software. Based on the modelling results, the analysis by electron beam microprobe and the detailed literature research, the phases spinel with up to 52 wt% and wuestite with up to 2.6 wt% Cr2O3 were identified as main carrier phases for Cr and thus also as important release determining phases. For V, dicalcium silicate with up to 0.62 wt% V2O5 could be named as an essential elution-determining factor.


Translated title of the contributionChemical and mineralogical characterization of ladle slag from voestalpine Linz GmbH
Original languageGerman
Awarding Institution
Award date31 Mar 2023
Publication statusPublished - 2023