Carbonation of Steel Slag II -SEM-EDS MICROANALYSIS USING PARC

19 Aug 2011

Sieger R. van der Laan, Christian Liebske; Tata Steel RD&T Ceramics Research Centre, IJmuiden, The Netherlands
Hans Kobesen; Tata Steel Europe, OSF2, IJmuiden, The Netherlands
Eleanor J. Berryman, Anthony E. Williams-Jones, Artasches A. Migdisov; McGill University, Canada.

One of the options that the steel industry has to mitigate some of its CO2 emissions is mineral carbonation of steel slag, a by-product of the steel refining process. Our study investigates reactions taking place during dissolution and carbonation of steel slag, with the aim of determining optimal conditions for conversion. A H2O-CO2 fluid is pumped through slag grains (2 – 3 mm) in a flow-through reactor at elevated pressure, and temperatures of 125 to 200°C, as described in a companion abstract [1]
The starting steel slag contains ~50 wt% CaO in larnite (Ca2SiO4), srebrodolskite (Ca2Fe2O5) and free lime. In addition, there is an inert phase, Mg-wuestite ((Fe,Mg)O)). After an experiment, entire cross sections of slag grains were analysed by SEM-EDS spectral imaging. Based on the information in the images, the volume proportions and distribution of reactant and product minerals were quantified using in-house developed PARC (PhAse Recognition & Characterization) software. This method reliably reproduces bulk compositions of solids as confirmed with XRF analysis [2]. The PARC results were used to calculate the mass balance between starting material, reacted slag and fluid and, in conjunction with the fluid chemistry, helped reconstruct the reaction path.

Paper presented at the Goldschmidt Conference, Prague, Czech Republic, August 14-19, 2011