Eignung von Sekundärrohstoffen für die Karbonatisierung

Research output: ThesisMaster's ThesisResearch

Abstract

Mineral Carbonation is a field of research with focus on the reduction of CO2-emissions. Its principle is based on the fixation of CO2 in Ca- and Mg- rich raw materials forming stable carbonates. If unwanted elements are removed during so called indirect process routes, the produced carbonates are rather pure and can be sold as products to generate added value. This aim is pursued by an FFG-funded research project called "CarboResources", conducted by the Montanuniversität Leoben. Within this project the present master thesis deals with detailed characterisation of potential secondary raw materials, which can represent an alternative to primary raw materials providing a contribution to resource conservation. Literature research revealed that in Austria Ca-rich iron- and steel slags as well as MSWI bottom ashes and wood ashes seem to be the most applicable secondary raw materials. These groups of materials amount to a total of 2.8 Mt per year. Based on the maximum theoretical CO2 uptake of 1.1 Mt approximately 1,5% of annual CO2-emissions in Austria could be fixed in these materials. Selected samples of a EAF stainless steel slag, two MSWI bottom ashes and one wood ash (bottom and fly ash) have been characterized by different chemical (XRF, ICP-MS, TOC) and mineralogical methods (XRD, EMPA, Raman spectroscopy). In stainless steel slags calcium (Ø 30.8% CaO) is preferably bound in calcium silicates (alite, larnite), gehlenite and to a minor degree also in brownmillerite and calciumchromite. Magnesium (Ø 6.9% MgO) is preferably bound in magnesiowüstite. Unfavourable is the high chromium-content as well as the poor processability of the slags. However, the samples also contain secondary metallurgical ladle slags with a high Ca-content of 53.6% CaO, preferably bound in aluminates (mayenite). The characterised MSWI ashes show calcium (about 21% CaO) preferably bound in melilite and the glass phase, to a minor degree also in wollastonite, larnite, plagioclase and portlandite. Besides considerable amounts of Ca are already naturally carbonated as calcite or dolomite. Magnesium occurs only subordinate (about 3% MgO). The same applies for the investigated wood ashes: having a higher CaO content of 27%, the majority is bound in melilite or its Mg-rich end member åkermanite, whereas the glass phase is depleted in Ca compared to MSWI ashes.

Details

Translated title of the contributionApplicability of secondary raw materials for mineral carbonation
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
Award date30 Oct 2015
Publication statusPublished - 2015