Directed precipitation of anhydrous magnesite for improved performance of mineral carbonation of CO2

Abstract

Highlights Two separate strategies to control precipitation of anhydrous magnesite have been investigated  Controlling carbonation process and products through investigating operation parameters such as temperature and pressure  Enhancement of the heterogeneous precipitation using seeding material  A ternary phase diagram is achieved which represents the relative concentration of possible precipitated phases: brucite (Mg(OH)2), magnesite (MgCO3) and hydromagnesit (Mg5(CO3)4(OH)2•4H2O

Mechanisms of Mg carbonates precipitation and implications for CO2 capture and utilization/storage

“…Yet, the extraction and carbonation of Mg(OH) 2 is kinetically hindered and may bring high energy penalties for the process. 145 Some reported experiments have investigated the direct gas-solid carbonation of brucite at elevated temperature and pressures to convert it into magnesite, but the process parameters need to be tuned according to the kinetics of the system: if the rate of dehydroxylation is much higher than the carbonation, the obtained product will be MgO instead of MgCO 3 . It has been observed the complete conversion of Mg (OH) 2 to magnesite under 500 °C, p(CO 2 ) of 36 bar, and p(H 2 O) of 4 bar for ca.…”

Advances in process development of aqueous CO2 mineralisation towards scalability

“…It was also suggested that adding magnesite seeds into the solution increased the nucleation rate based on this mechanism. Atashin et al (2017) studied the effect of heterogeneous seeding on Mg(OH)2 conversion efficiency. In the experiment, hydrophobic activated carbon and hydrophilic alumina were used at carbonation temperature under 100 -200 °C and CO2 pressure at 20-30 bar.…”

Anhydrous MgCO3: Controllable synthesis of various morphology based on hydrothermal carbonization

“…However, only a few reports are correlated with the synthesis of AMC, which are typically prepared under harsh conditions such as high CO 2 partial pressure (∼10 MPa), high temperatures (>150 °C), and/or long reaction time (>12h), with the products lacking size, morphology or structure homogeneity [9,10]. Liang et al [11] successfully synthesized the AMC under 3GPa and 800 °C for 1h based on the MgCO 3 •3H 2 O, whereas Lou et al [12] prepared the single crystal of AMC under 500 °C for 20 h by mixing the MgCO 3 powder, metallic sodium and carbon tetrachloride,.…”