Separation of Products from Mineral Sequestration of CO2 with Primary and Secondary Raw Materials

Abstract

Rising levels of greenhouse gases (GHG) in our atmosphere make it necessary to find pathways to reduce the amount of GHG, especially emissions of CO2. One approach is carbon capture and utilization by mineralization (CCUM). With this technology, it is possible to bind CO2 chemically from exhaust gas streams in magnesium or calcium silicates. Stable products of this exothermic reaction are carbonates and amorphous silica. Being amongst the biggest emitters of CO2, the cement industry has to find ways to reduce emissions. Geological mapping in Europe has been carried out to find suitable feedstock material, mainly olivines but also slags, to perform lab‑scale carbonation tests. These tests, conducted in a 1.5 L autoclave with increased pressure and temperature, have been scaled up to a 10 L and a 1000 L autoclave. The outcomes of the carbonation are unreacted feed material, carbonate, and amorphous silica, which have to be separated to produce substitutes for the cement industry as pozzolanic material (amorphous silica) or a value‑added product for other applications like paper or plastics (magnesite/calcite with bound anthropogenic CO2). Therefore, a process for the separation of ultrafine carbonation product was developed, consisting mainly of classification and flotation.