Design of a Continuous Process Setup for Precipitated Calcium Carbonate Production from Steel Converter Slag

Abstract

A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup.

A numerical Euler–Lagrange method for bubble tower CO2 dissolution modeling

“…Taking into account the dimensions for the stirred tank reactor presented by Mattila and Zevenhoven (2014) a modification of the geometry was made with the sole objective to study optimal bubble dissolution. The goal is to study the critical height of bubble dissolution for a defined initial bubble size in a given solution.…”

“…Design parameters by Mattila and Zevenhoven (2014) involved experimental rotational speeds of ∼80-∼120 rpm in the reactor to guarantee a level of mixing that assures precipitation of calcium carbonate. There, the Menter shear-stress transport (SST) model using the two equation k-ε turbulence model is selected considering the computational resources in terms of number of elements and fluid velocities allowing for rotational speeds within the experimental range mentioned.…”

“…1, right) and the focus of this work is the mass transfer and chemical reaction of a CO 2 bubble swarm while dissolving in a surrounding mixed liquid (water) phase. The carbonation process step requires a stable mixing and suspension of calcium salts that would react with a CO 2 stream (Mattila and Zevenhoven, 2014). In this paper, calcium ions and PCC particles are not yet considered.…”

“…E-mail address: Daniel.legendre@abo.fi (D. Legendre). (Mattila and Zevenhoven, 2014). This is a continuous process for CO 2 capture and utilization that includes mixers, a bubble reactor, inclined settlers and filters for PCC particles where CO 2 is dispersed in an aqueous solution that contains dissolved calcium (Ca 2+ ions), producing PCC, precipitated calcium carbonate (CaCO 3 ) particles.…”

Performance of Separation Processes for Precipitated Calcium Carbonate Produced with an Innovative Method from Steelmaking Slag and Carbon Dioxide

“…In order to minimize the use of washing water, a different washing approach than that used by Hudd was tested: washing water was added directly on top of the filtered cake, after which the water was pressed through the cake. The concentration of possible metals leached from steel slag was not studied here as this can be minimized by managing process parameters (Mattila and Zevenhoven, 2014b). The tests included pressure filtration and vacuum filtration, and the test series contained altogether 21 different filtration cycles with varying combinations of filtering, washing, and drying steps.…”