Synthesis of amorphous magnesium silicates with different SiO2:MgO molar ratios at laboratory and pilot plant scales

In this study, amorphous magnesium silicates with different SiO2:MgO molar ratios were synthesized by a precipitation reaction from magnesium sulfate (MgSO4), sodium silicate (Na2SiO3) and water. At laboratory scale, it was studied the effect of the SiO2:Na2O molar ratio of the Na2SiO3 solution used as a reagent on the properties of the amorphous magnesium silicates obtained. It was observed that this ratio is a key parameter in the synthesis process of these materials. The chemical composition and principal physicochemical properties were established, including textural properties from nitrogen adsorption/desorption isotherms and X-ray fluorescence. Moreover, some laboratory tests were scaled-up in an industrial pilot plant (ca. 103 times larger, i.e. 700 kg of wet product) demonstrating the high scalability of the materials obtained. The properties of the scaled-up materials were compared to those of different commercial materials containing magnesium silicate, such as Florisil® and Magnesia 430®. Analogous properties were achieved in terms of particle size distribution, humidity and pH and conductivity in solution.