Study On The Preparation Of High-purity MgO And Ultrafine Spherical Silica From Boron Mud

Boron mud is a solid residue of boron chemical products which prepared using boronore as raw material. Its main compositions are magnesia and silicon oxide. Theproduction technologies for preparation of high-purity MgO and ultrafine sphericalsilica from boron mud were studied in this thesis. The kinetics of acid boron mudleaching was investigated, the needed equipments in the production process wereselected, the economic benefit was calculated, and the environmental analysis wasestimated. The phase composition and morphology of products werecharacterized by XRD, SEM, and FT-IR.Boron mud was extracted by sulfuric acid, the leaching rate of MgO could reachabout99%at the optimum process conditions for acid leaching. The leaching processwas controlled by surface chemical reaction, the kinetics equation was k’t=(1-η)-2/3-1,and the apparent activation energy was52.7kJ·mol-1. Sulfuric acid leaching filtrate waspurified by the method of potassium permanganate oxidation and adjusting the pH. Therecovery rate of MgO was more than95%, both the removal rates of ferrum andmanganese were more than99%at the optimum process conditions for the purification.Under the optimum conditions, the ultrafine spherical silica prepared with the rawmaterial of sodium silicate which obtained from boron mud had an average particle sizeof300nm and a good dispersancy.The results of economic benefit estimation showed that the study on thepreparation of high-purity MgO and ultrafine spherical silica from boron mud couldobtain a good economical benefit. The environmental analysis showed that theprocess nearly had no waste pollution, and it was a clean production process.