Study On The Preparation Of Magnesia Phosphate Cement By Boron Mud

Many scholars have been studing the comprehensive utilization of boron mud since 1980s. Although several tens kinds of treatments about boron mud's problems; the pollution of boron mud also exist. The weight of accumulation about boron mud have been 10 million tons, and Large quantities of industrial wastes form in boron industry every year. These wastes have dual problems of disposal and health hazards. So the problem of boron mud needs to be resolved as soon as possible. Magnesia Phosphate Cement (MPC) not only have many excellent characters such as: quick hardening, high strength, excellent fire-proofing and so on, but also have less limitations than magnesium oxychloride cement (MOC) and magnesium oxysulfate cement (MOS) other MgO-based basic salt cement (BS), Such as better water resistance, better volume stability, better moisture resistance and so on. So MPC has a fine future in engineering projects, yet its application scope is limited greatly by the rapid rate of hydration reaction.At first, the author bases on the systemic researches of the properties of boron mud and compares with the sustainable development experiences from other kinds of solid wastes, and then proposes a novel theory which is about using boron mud to produce the MPC, and the boron mud MPC has a enough hydration reaction time.The author bases on the existing hydration mechanism of MPC, and discuss about the progress of hydration reaction on MPC in accurately, and discover that the concentration of H⁺ and the concentration of OH" are the two key factors influence the hydration reaction time, controlling either factors can extend the hydration reaction time. In this paper the author substitutes (NH₄)₂HPO₄ for NH₄H₂PO₄ to gain MPC, the result show that the hydration reaction time extends about 10 min.Based on the front research about MPC's hydration mechanism, the author uses the boron mud to produce the MPC. Although the boron mud MPC's hydration reaction time can reach 1 h, its preparation has more complex program. Because this preparation is no similar standard, the author has to take a primary progress in the whole research. The author gives a novel preparation, and investigates the factors about influencing the hydration reaction time and the strength, such as stopping time, the quality ratio among all kinds of matters, water solid ratio and so on. Using the combination of SEM and XRD to analyze the hydration mechanism and hydration product.In the last section of this paper, a novel theory about cement of carbonatites activated by acid and alkali is produced. Although the theory is only in a primary moment, this theory and the boron mud MPC have a fine foreground.