August 26, 2026 Dataset Open Access

Joseph, Praicy Ann; Debastiani, Rafaela; Ebert, Doreen; Möckel, Robert; Guy, Bradley Martin; Renno, Axel D.

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  <dc:creator>Joseph, Praicy Ann</dc:creator>
  <dc:creator>Debastiani, Rafaela</dc:creator>
  <dc:creator>Ebert, Doreen</dc:creator>
  <dc:creator>Möckel, Robert</dc:creator>
  <dc:creator>Guy, Bradley Martin</dc:creator>
  <dc:creator>Renno, Axel D.</dc:creator>
  <dc:date>2026-08-26</dc:date>
  <dc:description>Growing demand for sustainable metal production has increased interest in valorising metallurgical residues as secondary resources. The Waelz process commonly recovers Zinc from electric arc furnace dust, but it also produces significant amounts of Waelz slag containing valuable metals and minerals. Valorisation of Waelz slag via pyrometallurgical reduction smelting enables recovery of metals such as iron and manganese, providing a secondary resource and yielding a chemically stabilised secondary slag. The mechanisms controlling metal–slag separation and the development of internal microstructure during solidification remain under investigation. A comprehensive understanding of the chemical, mineralogical, and three-dimensional microstructural characteristics of this secondary slag is crucial for evaluating its properties and optimising its subsequent utilisation.

This study examines the three-dimensional structure and phase distribution of secondary Waelz slag produced by pyrometallurgical valorisation. X-ray computed tomography (XCT) served as the primary non-destructive characterisation method to reconstruct and quantify the slag's internal structure, focusing on the distribution, morphology, and size of gas-filled pores and metallic inclusions. XCT analysis was supplemented by X-ray diffraction (XRD) and elemental and mineralogical characterisation via SEM- based Automated minerology to correlate three-dimensional features with the material's chemical and phase composition.

XCT analysis identified a heterogeneous internal structure with pores and metallic inclusions exhibiting diverse sizes, morphologies, and spatial distributions. The results indicate systematic variations in porosity and metal fraction across the solidified slag.

The combined dataset shows that integrating XCT with XRD, XRF, and SEM-based Automated minerology links three-dimensional morphology, chemistry, and mineralogy in complex slag–metal systems. Correlation of XRD with SEM-based Automated minerology led to the proper identification of mineral phases present in the complex slag-metal system.

Although viscosity and surface tension can be simulated for experimental methods, the analytical workflow developed in this study provides a foundation for future research to quantify liquid slag viscosity and surface tension using XCT analysis. The technique-coupled correlative approach shows the necessity of a correlative workflow in an analysis.

 

X-ray computed tomography (XCT) datasets

Zip file with raw and reconstructed datasets from XCT for each of the subsamples from SWS_Bulk sample. For each scan, the folder is named as Sample_X, for example, Sample 1, and contains the raw data (“WS_S1_scan_00xxxx.tif), the “acquisition settings XRE.txt” file with the XCT scan information and a folder named “recon_WS_S1”, which refers to data reconstructed using Panthera software, a software based on filtered back projection algorithm. The reconstructed data corresponds to xy slices in .tif format.

 

Micro X-ray Fluorescence Spectroscopy (µXRF) datasets

“SWS XRF data” folder: excel file

Contains modal composition of the Secondary Waelz slag and the file is in the .xlsx format.

 

SEM-based Automated Mineralogy (MLA)

“SEM_Automated Mineralogy” folder contains BSE images and elemental maps of the MLA datasets for the sample SWS_S4 are .bmp or .png files. Bruker spectra are saved as .spx. and the .xlsx file contain the Measurement parameters, Modal minerology and Mineral reference.

MLA measurement parameters: 

Voltage: 25 kV

Spot size: 4.46

Specimen current: 10 nA

Working distance: 13 mm

Pixel Resolution: 1000

Horizontal field width: 1000 microns

BSE calibration (Cu): 244 BSE

X ray mapping BSE range: 30-255 BSE

 

MLA Measurement mode: GXMAP

Step size: 10 microns

Min feature size: ca.2 microns

Dwell time: 16 microsec

X ray acquisition time: 6 ms

 

MLA Measurement mode: XMOD

Step size: 25 microns

Dwell time: 8 microsec

X ray acquisition time: 8 ms

Avg Number X ray points: 533785

 

X ray Diffraction (XRD)

“SWS_XRD data” folder contains the XY file from the measurement, a figure of the XRD intensity plot, the weight percent quantification of the phases and the “SWS_Profex_BGMN_refined_XRD” folder, it contains the refined structural files of phases, BGMN refinement parameter file and XRD device measurement file.

XRD Measurement parameter

Tube. Cobalt X ray tube

Voltage. 35 kV

Current: 35 mA

Filter: Iron- beta filter

Theta – range: 5 to 80

Step size_ 0.0131 degrees

Sample area: 15 X 12 mm

Duration: 153 min

Reference database: ICDD PDF-5+ 2026</dc:description>
  <dc:identifier>https://rodare.hzdr.de/record/4980</dc:identifier>
  <dc:identifier>10.14278/rodare.4980</dc:identifier>
  <dc:identifier>oai:rodare.hzdr.de:4980</dc:identifier>
  <dc:language>eng</dc:language>
  <dc:relation>url:https://www.hzdr.de/publications/Publ-43837</dc:relation>
  <dc:relation>doi:10.14278/rodare.4979</dc:relation>
  <dc:relation>url:https://rodare.hzdr.de/communities/energy</dc:relation>
  <dc:relation>url:https://rodare.hzdr.de/communities/metallurgy_pilot_plant</dc:relation>
  <dc:relation>url:https://rodare.hzdr.de/communities/rodare</dc:relation>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>https://creativecommons.org/licenses/by/4.0/legalcode</dc:rights>
  <dc:subject>X-ray Computed Tomography</dc:subject>
  <dc:subject>Metallurgical Slag</dc:subject>
  <dc:subject>Secondary Waelz Slag</dc:subject>
  <dc:subject>X-ray Diffraction</dc:subject>
  <dc:subject>SEM-based Automated Minerology</dc:subject>
  <dc:subject>Correlative Characterisation.</dc:subject>
  <dc:title>"Data Publication Related to the Master's Thesis '3D Reconstruction of Gas-Filled Bubbles in Slag-Metal Systems: Characterization, Distribution, and Implications for Pyrometallurgical Processes," by Praicy Ann Joseph.</dc:title>
  <dc:type>info:eu-repo/semantics/other</dc:type>
  <dc:type>dataset</dc:type>
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