Research on the Low-Temperature Chemical Activation and Surface Modification Mechanism of Mg₄₀Ca_1.09Si_6.33(CO₃)₂

Magnesite is calcined to obtain active magnesium oxide, which is subsequently used in chemical reactions. There are high energy consumption and disorderly carbon dioxide emissions. Herein, direct utilization of all the elements in magnesite without roasting was achieved via surface modification activation technology. Sodium oleate was used as an activator; the reaction was carried out at 95°C for 4 h under alkaline conditions, and 60 mL sulfuric acid was added, resulting in the production of 9.5 g MgCO₃·3H₂O, 192.3 g magnesium sulfate heptahydrate, and 26.6 g wollastonite. The recovery rate reached 100%, while the conversion rate of magnesium oxide reached 83.6%. Density functional theory simulations revealed calcium and magnesium as the primary active sites. Sodium oleate adsorbs onto the magnesite surface through electrostatic adsorption and hydrogen bonding. Ionic and hydrogen bonds formed with Mg, Ca, and O in magnesite, which reduced the activation energy of magnesite. This paper presents a method for the chemical utilization of magnesite without roasting all the elements.