Suitability and Characterization of Secondary Raw Materials for Carbonation

Giv Noori Khadjavi

Research output: ThesisMaster's Thesis


The carbonation of mineral secondary raw materials offers an innovative approach for permanent storage of industrially generated CO2 in line with the principles of CCUS (Carbon Capture Utilization and Storage). Direct processes rely on the extraction of Ca and Mg ions and simultaneous reaction with CO2 in a single process step. The selection of suitable secondary raw materials as well as potential recycling routes of the generated solid output materials are the focus of this work. As part of the project "GreenRef", a variety of secondary raw materials which are generated in Austria were investigated regarding their availability and suitability for direct carbonation. Samples of potentially suitable waste incineration ashes, biomass ashes, paper residue incineration ashes, construction residue-fine fraction, cement bypass dusts, and spent refractory materials underwent detailed chemical and mineralogical characterization. Particularly alkaline spent refractory materials represent a waste group that has only hardly been investigated regarding its suitability for carbonation. Determination of the chemical composition was based on XRF, ICP-MS and TIC/TOC analyses, while characterization of crystalline and amorphous constituents was performed by means of XRD, SEM and investigations using polarization microscopy. The investigated spent refractory materials proved to be suitable for carbonation applications given their high amounts of MgO (up to 82.6 %), which is primarily bound in the form of periclase (MgO) and spinel (MgAl2O4). Likewise, the composition of selected paper residue incineration ashes, containing up to 60.4 % of CaO, present as free lime (CaO), portlandite (Ca(OH)2) and gehlenite (Ca2Al2SiO7), proved to be suitable for carbonation. The secondary raw materials were reacted with pure CO2 in an aqueous carbonation test in an autoclave for 6 hours at temperatures of 180 °C and a pressure of 20 bar. Subsequently, the solid reaction products underwent in-depth characterization in order to identify the generated materials and evaluate the carbonation success. Experimental CO2 uptake of the spent refractory materials was found to be within the range of 77.2 to 325.2 g CO2 per kg of input material. The CO2 uptake using paper residue incineration ashes reached a maximum of 174.3 g CO2 per kg of feedstock, corresponding to more than 46 % of the theoretical potential. Potential utilization routes for the generated solid output materials were identified as mineral lime and magnesium fertilizers as well as additives in cement production.
Translated title of the contributionEignung und Charakterisierung von Sekundärrohstoffen für die Karbonatisierung
Original languageEnglish
Awarding Institution
  • Montanuniversität
  • Sattler, Theresa, Co-Supervisor (internal)
  • Vollprecht, Daniel, Supervisor (external)
  • Pomberger, Roland, Supervisor (internal)
  • Melcher, Frank, Co-Supervisor (internal)
Award date30 Jun 2023
Publication statusPublished - 2023

Bibliographical note

embargoed until 20-06-2028


  • Mineral Carbonation
  • Mineral Waste
  • Carbon Capture Utilization and Storage
  • Municipal Solid Waste Incineration Ash
  • Fly Ash
  • Biomass Ash
  • Cement Bypass Dust
  • Paper Ash
  • Construction Waste

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