煤矸石多孔陶瓷的制备工艺研究

发布时间：2018-04-27 15:05

本文选题：添加造孔剂法 + 毛细管浆料法　；参考：《安徽建筑大学》2015年硕士论文

【摘要】：煤矸石是我国最大宗的工业固体废弃物,长期的露天堆积导致大量土地被占压,污染了水体、土壤和大气,对矿区的环境造成严重的危害,影响了人们的生命健康。随着科技的进步,煤矸石的综合利用有了较大的发展,应用范围不断扩大。通过对煤矸石中化学成分分析发现,其中主要的成份氧化硅和氧化铝与制备陶瓷的原材料相近,因此以煤矸石为原料制备多孔陶瓷,成为煤矸石资源化利用的新途径。多孔陶瓷是一种利用其孔隙结构获得优异的物理性能和力学性能的功能结构一体化材料,由于具有较高的显气孔率、均匀分布的微孔、有发达的比表面体积、耐高温、耐高压等优点,广泛应用于航空航天,医学、环保、建筑、石油化工等行业,在科学技术领域和国民建设中发挥这巨大作用。本文以淮南矿区煤矸石为主要原料,懫用添加造孔剂法和毛细管浆料法制备出了高气孔率、高强度的多孔陶瓷材料。主要研究了煤矸石的酸浸处理、烧成温度、保温时间、添加剂含量、莫来石纤维的添加量以及浆料的固相含量等对多孔陶瓷显气孔率、抗压强度、显微结构及物相等的影响。研究结果如下:1.制备陶瓷之前,研究了煤矸石原料的酸浸处理和煤矸石浆料的流变特性。(1)采用酸浸法对煤矸石的杂质含量进行控制,通过除铁率来表征杂质去除的效果。除铁率随着混酸浓度的增加而提高,当混酸浓度为5%HCl+21%H2SO4时,除铁率达到68.32%;之后,随着浓度的增加,除铁率几乎不再发生变化;(2)通过调节pH值和分散剂的添加量来获得高固相含量、低粘度的陶瓷浆料,随着pH值和分散剂含量的增加,浆料Zeta电位的绝对值呈先增大后减少的趋势,当pH值为10,聚羧酸分散剂的含量为0.1%时,Zeta电位的绝对值达到最大值56.75mV,此时,浆料的稳定性最好。2.采用添加造孔剂法制备多孔陶瓷,研究了以煤矸石中所含有的有机质为造孔剂制备多孔陶瓷的烧结工艺;再添加淀粉造孔剂进一步提高多孔陶瓷的显气孔率;并利用莫来石纤维改善了多孔陶瓷的高温收缩特性;最后以煤矸石为主要原料,配以适量氧化铝和氧化镁,低温制备了堇青石多孔陶瓷。(1)以煤矸石中所含有的有机质为造孔剂制备多孔陶瓷:对比了未经酸浸处理和酸处理后的煤矸石原料的烧结特性,随着烧结温度从1050℃升高到1300℃,酸处理煤矸石多孔陶瓷的抗压强度随烧结温度的升高由12.75 MPa增加到141.3MPa、显气孔率则由40.87%下降到9.21%;而未经酸处理的煤矸石多孔陶瓷,其抗压强度由31.60MPa增加至84.35 MPa(1250℃)后减小到50.10MPa,孔隙率则由35.72%下降到0.21%后增加到3.35%。这是由于煤矸石中的杂质在低温烧结时易形成固溶体活化晶格并产生液相,促进了烧结反应的进行。但是杂质含量过多时,在高温烧结时易产生大量的玻璃相和气泡,导致多孔陶瓷抗压强度急剧下降而显气孔率在降低到一定值后有所增加,因此必须采用有效的手段来控制煤矸石中的杂质含量。(2)以酸处理的煤矸石为原料制备出的多孔陶瓷显气孔率在50%以下,本文通过添加造孔剂的方法来进一步提高其显气孔率。1200℃煅烧后,添加60%的淀粉造孔剂可使多孔陶瓷的显气孔率由不加造孔剂时的24.55%增加到51.57%,此时多孔陶瓷的抗压强度为17.44mpa;并且随着造孔剂的含量由40%增加到70%,显气孔率由44.16%增加到55.54%。由此可见,添加造孔剂可显著提高多孔陶瓷的显气孔率。(3)为了改善多孔陶瓷的高温收缩性能,本文通过添加莫来石纤维来降低其高温烧结线性收缩率。在高温烧结过程中,随着烧结温度的增加,烧成收缩率逐渐增加,在1250℃时,烧成线性收缩率达到14.22%,显气孔率仅为48.57%,而当添加30%的莫来石纤维时,烧成线性收缩率仅为2.22%,此时的显气孔率达到65.62%。由此可见,莫来石纤维可有效降低多孔陶瓷的烧成收缩率,提高其显气孔率。(4)以煤矸石为原料,通过对多孔陶瓷孔隙结构和机械性能的调节以及对其制备工艺的探索研究,制备除了高孔隙率、高强度的多孔陶瓷,为了进一步提高煤矸石的资源化利用水平,通过配以适量氧化铝和氧化镁,在低温条件下制备出了具有低热膨胀系数和优良热振稳定性的堇青石多孔陶瓷。在烧结温度达到1200℃时,堇青石相开始出现,随着烧结温度和保温时间的增加,堇青石的含量逐渐增加,当温度达到1225℃,即可得到纯度较高的堇青石多孔陶瓷。相比于采用其他的原料制备的堇青石多孔陶瓷,其烧结温度降低了约100℃。3.为了进一步探索减少多孔陶瓷在干燥和烧成过程中收缩的工艺条件,本文探讨了一种新型的多孔陶瓷制备方法,即毛细管浆料法。先利用纯度较高的石英砂为原料,探索毛细管浆料法制备多孔陶瓷的工艺,然后利用此方法制备煤矸石多孔陶瓷。(1)以石英砂为原料,探讨助烧剂对多孔陶瓷烧结性能的影响,结果表明,助烧剂可以显著改善多孔陶瓷的烧结性能,并且三元助烧剂的效果优于二元系统。在不加助烧剂的情况下,1610℃时,多孔陶瓷的显气孔率为55.82%,而抗压强度为仅为0.83mpa,而添加(5%cao+3%al2o3+2%mgo)混合料为助烧剂,在1370℃时,多孔陶瓷的显气孔率和抗压强度分别达到40.14%和4.48mpa,极大的降低了烧成温度。(2)以煤矸石为原料,以过0.075mm方孔筛的细煤矸石和5%cao+3%al2o3+2%mgo混合料为助烧剂,在不同烧结温度的作用下,考察显气孔率和抗压强度的变化,结果表明5%cao+3%al2o3+2%mgo混合料的助烧效果明显优于细煤矸石,以混合料为助烧剂、1250℃烧结的样品,其抗压强度和显气孔率分别为20.71mpa和34.97%,而添加细煤矸石的样品,抗压强度和显气孔率分别为为0.75MPa和50.75%。但进一步增加助烧剂含量,对于提高烧结性能效果并不明显。
[Abstract]:Coal gangue is the most important industrial solid waste in China. A long period of open pit accumulation has caused a large amount of land to be pressed, polluting the water, soil and atmosphere, causing serious harm to the environment of the mining area and affecting people's life and health. With the progress of science and technology, the comprehensive utilization of coal gangue has been greatly developed and the application scope is expanding continuously. Through the analysis of the chemical composition in the gangue, it is found that the main components of the silica and alumina are similar to the raw materials prepared. Therefore, the preparation of porous ceramics with coal gangue as raw material has become a new way for the utilization of coal gangue. Porous ceramics are a kind of excellent physical and mechanical properties by using its pore structure. The functional structure integrated materials have been widely used in aerospace, medical, environmental, construction, petrochemical and other industries because of the advantages of high porosity, uniform distribution of micropores, developed specific surface volume, high temperature resistance and high pressure resistance, which play a great role in the field of science and technology and national construction. This paper is based on coal mining in Huainan mining area. High porosity and high strength porous ceramic materials are prepared by adding hole agent method and capillary slurry method. The main research is the acid leaching of coal gangue, sintering temperature, heat preservation time, additive content, adding amount of mullite fiber and solid content of slurry to porous ceramics. The results are as follows: 1. before preparing the ceramics, the acid leaching of the gangue raw materials and the rheological properties of the coal gangue slurry were studied. (1) the impurity content of the gangue was controlled by acid leaching, and the removal efficiency of the impurity was characterized by the iron removal rate. The iron removal rate was raised with the increase of the mixed acid concentration. High, when the concentration of mixed acid is 5%HCl+21%H2SO4, the iron removal rate is 68.32%. After the increase of the concentration, the iron removal rate is almost no longer changed. (2) the high solid content is obtained by adjusting the pH value and the addition of dispersant. With the increase of the pH value and the dispersant content, the absolute value of the Zeta potential of the slurry is increased first. After the decreasing trend, when the pH value is 10 and the content of polycarboxylic acid dispersant is 0.1%, the absolute value of Zeta potential reaches the maximum value 56.75mV. At this time, the best stability of the slurry is to prepare porous ceramics by adding pore forming agent, and study the sintering process of preparing porous ceramics by the organic matter contained in the gangue, and then adding starch. The porosity of porous ceramics is further improved and the high temperature shrinkage characteristics of porous ceramics are improved by using mullite fiber. At the end, the porous ceramics of cordierite are prepared at low temperature with the coal gangue as the main raw material, with a proper amount of alumina and Magnesium Oxide. (1) the porous ceramics are prepared by the organic matter in the gangue. Compared with the sintering characteristics of coal gangue raw materials without acid treatment and acid treatment, with the sintering temperature rising from 1050 to 1300, the compressive strength of the acid treated coal gangue porous ceramics increased from 12.75 MPa to 141.3MPa with the increase of sintering temperature, and the apparent porosity decreased from 40.87% to 9.21%; and the untreated coal gangue porous ceramics, The compressive strength is increased from 31.60MPa to 84.35 MPa (1250 C) to 50.10MPa, and the porosity is decreased from 35.72% to 0.21% to 3.35%., which is due to the impurities in the coal gangue which can easily form the solid solution activation lattice and produce the liquid phase at low temperature sintering, and promote the sintering reaction. But the impurity content is too high at high temperature. It is easy to produce a large number of glass and bubbles, resulting in a sharp decline in the compressive strength of porous ceramics and an increase in the apparent porosity after reducing to a certain value. Therefore, effective means must be used to control the content of impurities in the gangue. (2) the porosity of porous ceramics prepared from the coal gangue treated with acid is less than 50%. After adding the pore forming agent to further improve its apparent porosity.1200 C calcinations, adding 60% of the starch pore forming agent can increase the apparent porosity of porous ceramics from 24.55% to 51.57% when the porosity is not added, and the compressive strength of the porous ceramics is 17.44mpa, and with the increase of pore forming agent from 40% to 70%, the apparent porosity is 44.16%. The increase to 55.54%. shows that the porosity of porous ceramics can be significantly increased by adding pore making agents. (3) in order to improve the high temperature shrinkage of porous ceramics, the linear shrinkage rate of high temperature sintering is reduced by adding mullite fiber. In the process of high temperature sintering, the sintering shrinkage rate increases with the increase of sintering temperature, at 1250. At C, the linear shrinkage rate was 14.22% and the apparent porosity was only 48.57%. When the 30% mullite fiber was added, the linear shrinkage rate was only 2.22%. The apparent porosity reached 65.62%., and the mullite fiber could effectively reduce the sintering shrinkage of porous ceramics and increase the apparent porosity. (4) coal gangue was used as the raw material. In order to further improve the resource utilization level of coal gangue, in order to further improve the utilization level of coal gangue, the low thermal expansion coefficient and good quality are prepared under low temperature conditions in order to further improve the utilization level of coal gangue in order to further improve the utilization level of the coal gangue, in order to improve the porous and high strength porous ceramics. Cordierite porous ceramics with hot vibration stability are formed when the sintering temperature reaches 1200 degrees C. The cordierite content increases with the increase of sintering temperature and holding time. When the temperature reaches 1225, the cordierite porous ceramics with higher purity can be obtained. Compared to the cordierite porous materials prepared with other raw materials, the cordierite porous ceramics can be obtained. In order to further explore the technological conditions for reducing the shrinkage of porous ceramics during drying and firing process, the sintering temperature of ceramics was reduced by about 100.3.. A new method of preparation of porous ceramics, namely, capillary slurry method, was discussed in this paper. This method is used to prepare the coal gangue porous ceramics. (1) the effect of sintering aid on the sintering properties of porous ceramics is investigated with quartz sand as raw material. The results show that the sintering agent can significantly improve the sintering properties of porous ceramics, and the effect of three element burning AIDS is superior to two yuan system. Under the condition of no burning AIDS, more Kong Tao at 1610. The apparent porosity of porcelain is 55.82%, while the compressive strength is only 0.83mpa, and the addition of (5%cao+3%al2o3+2%mgo) mixture is a burning AIDS. At 1370, the apparent porosity and the compressive strength of the porous ceramics are 40.14% and 4.48mpa, respectively, and the sintering temperature is greatly reduced. (2) the gangue and 5%cao+ with the coal gangue as the raw material and the 0.075mm square hole sieve. 3%al2o3+2%mgo mixture was used as a sintering aid. The changes of apparent porosity and compressive strength were investigated under different sintering temperatures. The results showed that the burning effect of 5%cao+3%al2o3+2%mgo mixture was obviously better than that of fine coal gangue, and the mixture was used as a sintering aid. The compressive strength and the apparent porosity of the samples sintered at 1250 C were 20.71mpa and 34.97% respectively. With the addition of fine coal gangue, the compressive strength and the apparent porosity are 0.75MPa and 50.75%. respectively, but further increase the content of the burning agent, and the effect of increasing the sintering performance is not obvious.

【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.7

【参考文献】