An Efficient and Sustainable Approach for Preparing Silicon Fertilizer by Using Crystalline Silica from Ore

Silicon fertilizer has been prepared by converting crystalline silica from ore into plant-available silicon using a roasting method. The results of roasting experiments showed that adding limestone as an additive ingredient and sodium hydroxide as a roasting fluxing agent significantly increased the conversion rate of plant-available silicon. Both the roasting temperature and fluxing agent are key factors in the production process of silicon fertilizer. The roasting mechanism was studied by thermogravimetry-differential scanning calorimetry (TG-DSC) and x-ray diffraction (XRD) analysis. The TG-DSC results indicated that, in the presence of the fluxing reagent, the decomposition temperature for limestone and the initial reaction temperature for the conversion were reduced by 22.1 degrees C and 33.2 degrees C, respectively. These results also revealed that plant-available silicon conversion is an endothermic reaction without flux but an exothermic reaction with flux. The XRD results showed that the effective components of the silicon fertilizer were CaSiO3, Ca2SiO4, and Ca3SiO5.