利用盐湖提锂副产含硼氧化镁制备磷酸镁水泥的试验研究

发布时间：2018-04-24 19:42

  本文选题：快速修补材料 + 磷酸镁水泥　； 参考：《中国科学院研究生院(青海盐湖研究所)》2014年硕士论文

【摘要】：磷酸镁水泥(Magnesium Phosphate Cement,MPC)材料是一种气硬性胶凝材料。由于其具备快硬、早强、黏结力强、体积稳定性好、耐久性好和环境温度适应能力强等优点而备受关注,但是传统的MPC制备成本很高,所以限制了其在工程上大量的使用。本文首次利用盐湖提锂副产含硼氧化镁作为重烧MgO的替代原料用来制备MPC。首先对含硼氧化镁在不同温度下进行了热处理,测定了其在不同热处理温度下物理性质和化学性质的变化。然后通过系统实验,探讨了含硼氧化镁热处理温度、M/P、不同种类磷酸盐对MPC性能的影响,通过性能对比找出了制备MPC的最优配比,并分析了最优配比下的MPC物相组成和微观形貌。此外,在最优配比条件下通过掺加矿物掺合料,通过在空气中养护、淡水和模拟海水中浸泡后MPC的性能变化,分析了物相和微观形貌的变化,找出了最优的矿物掺合料掺量,制备出的MPC材料不仅使MPC制备成本显著降低,还实现了盐湖资源循环利用。取得的主要研究成果如下:(1)测定了含硼氧化镁的热处理及其物理与化学性质变化。采用不同温度热处理含硼氧化镁,并采用低真空扫描电镜(SEM)和X射线衍射-全谱分析(XRD-Total Pattern Solution,XRD-Topas)定性定量法分析了含硼氧化镁在不同热处理温度下的物相组成及微观形貌;采用粒度分析仪(Laser particle size analyzer,LSPA)和静态氮吸附仪(Static nitrogen adsorption analyzer,SNAA)分别测定了含硼氧化镁在不同热处理温度下的粒度分布、比表面积和总孔体积,并用水合法测定了其在不同温度下热处理后其中活性MgO含量。结果表明:热处理温度对含硼氧化镁的物相组成产生影响。在热处理以前,大量的Mg(OH)2存在于原材料含硼氧化镁中;在热处理以后,Mg(OH)2全部转化成MgO。此外,含硼氧化镁的比表面积、形变系数、总孔体积和活性MgO含量随含硼氧化镁热处理温度的升高而降低。(2)确定了制备MPC的最优配比。以凝结时间以及早期、后期抗压强度为性能考察指标,并结合制备成本来系统地研究了含硼氧化镁的热处理温度、含硼氧化镁与磷酸盐的摩尔比(M/P摩尔比)和磷酸盐的种类对MPC性能的影响。结果表明:制备低成本高性能的mpc材料的最优配比为:含硼氧化镁的热处理温度为1000℃~1200℃,m/p比为6,磷酸盐为kh2po4。(3)利用矿物掺合料技术研究了高性能mpc(英文全称,hpmpc)的制备技术、基本性能与耐久性。在最优配比mpc的基础上,分别研究了不同掺量的粉煤灰和矿渣对mpc的凝结时间、抗压强度、抗水性和抗海水腐蚀性能的影响。结果表明:mpc的凝结时间随矿物掺合料掺量的增加而逐渐延长。随着粉煤灰和矿渣的继续增加,抗压强度则随矿物掺合料的增加先保持不变,而后持续下降;而mpc的抗水性和抗海水腐蚀性能则随矿物掺合料的增加而逐渐增强。其中,当粉煤灰掺量为40%,或矿渣掺量为20%时,不仅可以满足快速修补材料的性能要求,还可明显改善mpc的抗水性和抗海水腐蚀性能。在水中和模拟海水中浸泡60d后,掺加粉煤灰和矿渣的hpmpc的软化系数和抗海水腐蚀系数分别达到0.83~0.81和0.97~0.86。此外,矿物掺合料的掺加还可显著降低mpc的制备成本。(4)分析了mpc的微观物相和sem形貌。(a)基准mpc微观物相和形貌的分析。在制备mpc的最优条件的基础上,对基准mpc的物相组成和微观形貌进行了分析。结果表明:mpc的主要水化产物为mgkpo4·6h2o(mkp),且随着水化龄期的延长,水化反应随养护龄期延长而不断进行。通过微观结构特征分析可发现,mpc在水化早期(3h),水化产物为粗块状的凝胶。继续养护至28d后,大量的细棒状的成熟的mkp晶体生成。(b)掺矿物掺合料hpmpc的微观物相和形貌的分析。矿物掺合料的掺入对hpmpc的水化产物和微观结构产生明显的影响。掺加矿物掺合料之后随着养护龄期的延长,mkp的含量逐渐增多,表明水化反应不断进行。由微观结构分析可知,在水化早期(3h),大量的粗块状mkp凝胶生成。随着龄期的延长,大量细棒状mkp晶体形成,此外,矿物掺合料表面发生了火山灰反应。(c)矿物掺合料hpmpc具有较高的抗水性与抗海水腐蚀性的微观结构机理。由物相分析可知,随着在水中和模拟海水中养护龄期的延长,mkp含量逐渐增多,矿物掺合料hpmpc的水化反应仍在缓慢进行。通过微观分析发现,基准MPC净浆试件浸泡60 d后,基体孔隙较多。而掺矿物掺合料HPMPC在浸泡60 d后基体很密实,这主要是由于矿物掺合料发挥了微集料效应。(5)分析了水化产物的生长机理。(a)基准MPC水化产物的演变过程。在水化早期(3 h),形成了大量的粗块状的无定型的镁-磷酸钾盐络合物水化凝胶(MKP凝胶)。这种MKP凝胶的化学组成为缺镁富磷的。随着水化龄期的延长,在MPC硬化体内部的饱和溶液中,水合Mg2+继续进入MKP凝胶的化学结构中,从而导致MKP凝胶逐渐析晶、成核、生长成“成熟”的细棒状的水化产物MKP晶体。(b)矿物掺合料HPMPC的水化产物演变过程。在水化早期(3 h),形成大量的MKP凝胶。继续水化至28 d后,成熟的MKP晶体大量形成。此外,矿物掺合料发挥了火山灰效应,其中的活性物质与MKP晶体反应生成含有镁、钾、磷、铝、硅的凝胶水化产物(MKPAS凝胶),覆盖在矿物掺合料表面。(c)基准MPC和矿物掺合料HPMPC在水中和模拟海水中的水化产物演变过程。基准MPC在水中和模拟海水中浸泡60 d后,一部分MKP凝胶被溶蚀出来,从而留下较多的孔隙,导致其抗水性和抗海水腐蚀性低。MPC掺入矿物掺合料之后,还发挥了微集料效应和吸附效应,保留未成熟的MKP凝胶和MKPAS凝胶于基体中,使未成熟的MKP凝胶随着浸泡时间的延长,逐渐成核、生长成成熟的MKP晶体。因此,矿物掺合料HPMPC具有较高的抗水性与抗海水腐蚀性。其中,矿渣HPMPC的抗水性与抗海水腐蚀性要优于粉煤灰HPMPC,其主要原因是由于矿渣自身水化形成了C-S-H凝胶,进一步增强矿渣HPMPC的抗水性与抗海水腐蚀性。
[Abstract]:Magnesium phosphate cement (Magnesium Phosphate Cement, MPC) is a kind of pneumatic cementitious material. Because of its advantages of fast hardening, early strength, strong bonding force, good volume stability, good durability and strong adaptability to environmental temperature, the traditional MPC preparation is very high, so it restricts its large amount of use in Engineering. For the first time, the boron containing boron containing Magnesium Oxide Magnesium Oxide was used as a substitute for reburning MgO to prepare MPC. for the first time to heat the boron containing Magnesium Oxide at different temperatures. The physical and chemical properties of the boron containing boron were measured at different heat treatment temperatures. Then the heat treatment temperature of boron containing Magnesium Oxide was investigated by system test, and M/P was investigated. The effect of different kinds of phosphate on the performance of MPC was found through performance comparison, and the optimal ratio of MPC was found. The phase composition and Micromorphology of MPC under the optimal ratio were analyzed. In addition, the performance changes of MPC in fresh water and simulated seawater were analyzed by adding mineral admixtures in the optimum ratio. The best mineral admixture content was found out by the change of the phase and Micromorphology. The prepared MPC material not only reduced the cost of the preparation of MPC significantly, but also realized the recycling of Saline Lake resources. The main results obtained are as follows: (1) the heat treatment and the physical and chemical properties of boron containing Magnesium Oxide were measured. Boron containing Magnesium Oxide was treated with low vacuum scanning electron microscopy (SEM) and X ray diffraction full spectrum analysis (XRD-Total Pattern Solution, XRD-Topas). The phase composition and Micromorphology of boron containing Magnesium Oxide at different heat treatment temperatures were analyzed. The particle size analyzer (Laser particle size analyzer, LSPA) and static nitrogen adsorption apparatus were used. The particle size distribution, specific surface area and total pore volume of boron containing Magnesium Oxide at different heat treatment temperatures were measured by Static nitrogen adsorption analyzer, SNAA respectively. The content of active MgO was determined by water treatment at different temperatures. The results showed that the heat treatment temperature had an effect on the phase composition of boron containing boron. Before heat treatment, a large number of Mg (OH) 2 existed in the raw materials containing boron containing Magnesium Oxide; after heat treatment, Mg (OH) 2 was transformed into MgO.. The specific surface area of boron containing Magnesium Oxide, the deformation coefficient, the total pore volume and the content of active MgO decreased with the rise of the heat treatment temperature of the boron containing Magnesium Oxide. (2) the optimum ratio of the preparation of MPC was determined. Setting time was determined. And the early and late compressive strength is the performance evaluation index, and the preparation cost is combined to systematically study the heat treatment temperature of boron containing Magnesium Oxide, the effect of the types of Molby (M/P Molby) and phosphate on the properties of MPC with boron containing boron and phosphate. The results show that the optimum ratio of the preparation of low cost and high performance MPC is boron containing boron. The heat treatment temperature of Magnesium Oxide is 1000 ~1200 C, m/p ratio is 6, phosphate is kh2po4. (3) using mineral admixture technology to study the preparation technology of high performance MPC (English full name, HPMPC), basic properties and durability. On the basis of the optimal ratio MPC, the condensation time and compressive strength of the fly ash and slag on MPC are studied, and the compressive strength is strong. The results show that the setting time of MPC gradually extends with the increase of mineral admixture. With the increase of fly ash and slag, the compressive strength remains unchanged and then continues to decrease with the increase of mineral admixture, while the water resistance and corrosion resistance of MPC are followed by minerals. The addition of the admixture increases gradually. When the amount of fly ash is 40%, or the slag content is 20%, it can not only meet the performance requirements of the fast repair material, but also improve the water resistance and corrosion resistance of MPC. After soaking in water and simulated seawater for 60d, the softening coefficient of HPMPC mixed with fly ash and slag and the resistance to the sea can be obtained. The water corrosion coefficient is 0.83~0.81 and 0.97~0.86. respectively, and the addition of mineral admixture can also significantly reduce the preparation cost of MPC. (4) analysis of the microscopic phase and SEM morphology of MPC. (a) analysis of the phase and morphology of the reference MPC microphase. On the basis of the optimum conditions for preparing MPC, the phase composition and Micromorphology of the reference MPC are divided. The results show that the main hydration products of MPC are mgkpo4 6H2O (MKP), and with the prolongation of the age of hydration, the hydration reaction continues with the prolongation of the curing age. Through the analysis of microstructure characteristics, it is found that MPC is in the early hydration (3H) and the hydration products are thick lumpy gelation. After maintaining to 28d, a large number of fine rod like mature MKP crystals are maintained. Analysis of the microstructure and morphology of the mineral admixture (b) doped with mineral admixture HPMPC. The addition of mineral admixtures has a significant effect on the hydration products and microstructure of HPMPC. After adding mineral admixtures, the content of MKP increases with the prolongation of the curing age, indicating that the hydration reaction is continuously carried out. In the early period (3H), a large number of coarse MKP gels were formed. With the prolongation of the age, a large number of fine rod like MKP crystals were formed. In addition, the surface of mineral admixtures had a volcanic ash reaction. (c) mineral admixture HPMPC had a high water resistance and corrosion resistance of the microstructure mechanism. By phase analysis, it is known that with the water and simulated seawater The content of MKP increases gradually, and the hydration reaction of mineral admixture HPMPC is still slow. It is found that the matrix pore is more than that of the base MPC paste specimen after 60 d immersion. And the mineral admixture HPMPC is very dense after soaking 60 d, which is mainly due to the effect of the mineral admixture on the micro aggregate. (5) The growth mechanism of the hydration products was analyzed. (a) the evolution process of the datum MPC hydration products. At the early stage of hydration (3 h), a large number of thick, amorphous magnesium phosphate potassium salt complex hydrogel (MKP gel) was formed. The chemical composition of this MKP gel was magnesium deficiency and phosphorus rich. With the prolongation of the age of hydration, the saturated solution inside the MPC hardened body was extended. In addition, the hydration of Mg2+ continues to enter the chemical structure of the MKP gel, resulting in the gradual crystallization of MKP gels, nucleation and growth of a "mature" fine rod like hydration product MKP crystal. (b) mineral admixture HPMPC hydration product evolution process. In the early hydration (3 h), a large number of MKP gels are formed. After continued hydration to 28 d, a large number of mature MKP crystals In addition, mineral admixtures play a volcanic ash effect, which reacts with the MKP crystal to produce magnesium, potassium, phosphorus, aluminum, silicon gel hydration products (MKPAS gels), covering the mineral admixture surface. (c) reference MPC and mineral admixture HPMPC in water and simulated seawater, the evolution process of hydrated products in water and simulated seawater. The reference MPC is in water. After soaking in the simulated seawater for 60 d, a part of the MKP gel was dissolved and left more pores, resulting in its water resistance and low corrosion resistance to the mineral admixture, and after the addition of mineral admixture, the micro aggregate effect and adsorption effect were also played. The immature MKP gels and MKPAS gels were retained in the matrix, so that the immature MKP gel was soaked with the.MPC. The prolongation of bubble time, gradually nucleation, and mature MKP crystal. Therefore, mineral admixture HPMPC has high water resistance and seawater corrosion resistance. Among them, the water resistance and seawater corrosion resistance of the slag HPMPC are superior to the fly ash HPMPC. The main reason is that the slag itself hydrated to form the C-S-H gel and further enhanced the slag HPMPC. Water resistance and seawater corrosion resistance.

【学位授予单位】：中国科学院研究生院(青海盐湖研究所)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TQ172.7
，

本文编号：1797960