【作者】 郭成洲；

【导师】 陈文； 朱教群；

【作者基本信息】 武汉理工大学 ， 材料学， 2012， 博士

【摘要】 农业和化工业每年会产生大量的工业副产品,其中如磷渣和磷石膏具有双重危害,即不仅会带来处理难题,而且造成环境污染。磷渣和磷石膏具备潜在活性,可以作为水泥工业的添加剂而得到广泛应用。然而在中国,每年有大量的磷渣和磷石膏得不到有效利用,究其原因,主要是其中所含的磷和氟严重延缓水泥的凝结时间,并降低早期强度。为了改善这一缺点,本文重点研究了磷渣和磷石膏中磷和氟对水泥单矿硅酸三钙和铝酸三钙的水化机理影响。在此基础上,采用化学方法来激发磷渣和磷石膏的活性,选取碱性物质如生石灰、氢氧化钠、硅酸钠以及盐类如氯化钠等,来加快掺加磷渣和磷石膏水泥的水化速率。制备硅酸三钙和铝酸三钙,以磷渣浸泡液和磷石膏浸泡液代替水,通过量热分析、化学结合水、XRD和SEM等方法,探讨磷和氟对水泥单矿硅酸三钙和铝酸三钙水化进程的影响。研究表明,可溶性磷和氟对水泥单矿的水化反应有明显的延缓作用。硅酸三钙在含磷和氟溶液中的水化放热量显著降低,而且诱导期延长,推迟了第二放热峰的出现,体现在整个放热曲线上呈现放热峰的峰值低,峰出现时间推迟的特点。铝酸三钙在含磷和氟溶液中的水化放热峰推迟出现,水化产物数量减少。难溶性磷对水泥单矿的水化也有一定的延缓作用,难溶性氟对单矿物的水化放热速率影响很小。SEM图像表明,由于磷和氟对水化延缓的作用,使得单矿物硬化浆体早期微观形貌存在少量孔隙,裂缝出现概率减少。将不同形态的磷酸盐和氟盐外掺引入硅酸盐水泥,结果表明：磷和氟对硅酸盐水泥物理性能的不利影响主要是由其中的可溶磷和氟造成的,难溶磷和氟对水泥物理性能的影响很小,可溶磷中以HPO42-对水泥物理性能的影响最大。针对磷渣材料的特性,采用碱激发剂对磷渣进行改性,结果表明：氢氧化钠、碳酸钠及其与尿素或氯化钠的复合都可以加速磷渣的水化,但是氢氧化钠的复合作用更明显。激发剂对磷渣活性的激发主要发生在磷渣水化早期,后期增幅不大。掺加生石灰能够提高磷渣硅酸盐水泥的3d和28d强度。3d强度比未掺生石灰的磷渣硅酸盐水泥提高0.5MPa,增长率2.0%,28d强度可以提高4.7MPa,增长率12.2%。针对磷石膏的特性进行系列研究,将磷石膏代替天然石膏作为硅酸盐水泥的组分掺入,测定水泥的强度和凝结时间。结果表明：在相同SO3掺量的条件下,同天然石膏相比,磷石膏会降低水泥的早期强度,提高后期强度,显著延长凝结时间。矿渣或粉煤灰取代部分熟料掺入,能够减弱磷石膏对水泥强度的不利影响,但会延长水泥的凝结时间。筛分、煅烧和石灰中和对磷石膏的性能均有所改善,通过2wt%生石灰预处理后的磷石膏可以用作硅酸盐水泥的调凝剂。更多还原

【Abstract】 Large quantities of industrial by-products are produced every year by chemical and agricultural process industries. These materials such as phosphorous slag(PS) and phosphor gypsum(PG) are latent active material and its utilization as addition is a important approach to cement development. In China, a lot of phosphorous slag and phosphor gypsum has not been used widely and effectively. The main reason is that the fluorine and phosphorus in phosphorous slag and obviously lengthens the setting time and decreases the early strength of cement. Consequently, it can affect the engineering construction progress. Studys show that addition of activation, such as calcined gypsum, calcined alumstone and sodium sulphate, can resolve these questions and improve the properties of cement. In order to improve these faults of PS and PG, effect of fluorine and phosphorus in phosphorous slag and phosphogypsum on hydration process of C3S and C3A was explored. Base on this results, chemical methods was used in this study. Alkali activators such as calcined lime, sodium hydrate and sodium chloride were used to accelerate hydration speed of PS and PG cement.Both of tricalcium silicate(C3S) and tricalcium aluminate(C3A) were prepared by burning. Phosphate slag and phosphor gypsum soak solution instead of water were used. By means of hydration heat rates, chemical bonding water, XRD and SEM, the effect of the phosphorus and fluoride on the hydration process of cement minerals were explored. Studies have shown that the soluble phosphorus and fluoride can obviously put off the hydration of cement minerals. Compared with the hydration process in the water solution, the process that C3S in the phosphate slag and phosphor gypsum soak solution releases less heat quantity, and the induction period prolongs, the first exothermic peak of immersing is markedly lower, consequently delays the appearance of the second exothermic peak. The characteristic, which is reflected in the whole exothermic curve, takes on a phenomenon that the exothermic peak is low, and the appearance of the peak is delayed. Furthermore, insoluble calcium phosphate has a certain function of delaying cement single mineral hydration, and insoluble calcium fluoride almost takes little effect on the hydration rate of C3S and C3A. Because of the delayed effect of phosphate and fluoride in the hydration process, there exist a few pores in the micro-structure of early hardened paste, whereas they could also reduce the chance of cracks.When various forms of phosphate and fluoride are added in the Portland cement, it is found that the negative effect on the cement is mainly caused by the soluble ones in which HPO42-has the greatest effect, and the insoluble ones has little impact.According to characteristics of phosphorus slag, chemical methods was used to stimulate the activity of phosphorus slag. The results show that NaOH(or NaaCO3), together with the compound of CO(NH2)2or NaCl, can accelerate the hydration of phosphorous slag cement. However, when NaOH combined with CO(NH2)2or NaCl, the affect of the combination is more obvious. The stimulation function of activator to phosphorus slag, mainly occurs in the early-age hydration of phosphorus slag, but the late-age of which fluctuates slowly. CaO can heighten the strength of3days and28days of phosphorous slag cement. When compared with phosphorous slag cement mixed with no CaO, the strength of3days can increase0.5MPa (2.0%/growth rate), meanwhile, the strength of28days can increase4.7MPa(12.2%/growth rate).In this study, a series of research work was carried on phosphor gypsum. The strength and setting time of cement in which PG was used as retarder were determined. Compared with natural gypsum with the same SO3wt%added in the cement, the results show that PG can reduce the early strength, increase the late strength and extend the setting time of cement. When slag or fly ash is added to replace certain clinker, the adverse effect of PG on strength of cement can be reduced, but the setting time has also been delayed. In addition, the quality of PG can be improved by sifting, calcining or liming. With2wt%lime, PG can be used as retarder of cement.更多还原