利用钢渣制备高钙高铁陶瓷的基础及应用研究

发布时间：2018-04-25 03:05

本文选题：钢渣 + 陶瓷　；参考：《北京科技大学》2017年博士论文

【摘要】：工业的快速发展产生了大量的固体废弃物,其不仅占用大量土地,而且污染环境,严重制约了社会的可持续发展。陶瓷不但能够将复杂化学组分的硅酸盐固废转变为优良性能的材料,而且具有高的附加值。另一方面,陶瓷工业具备消纳大宗固废的能力,并且随着优质原料的减少和自然资源开采的限制,陶瓷工业也面临着利用低品位矿物或工业固废的巨大需求。因此,制备陶瓷材料是利用固废的一条有效途径。传统的粘土-长石-石英三元陶瓷属于K2O(Na2O)-Al2O3-SiO2体系,其要求CaO和Fe2O3组分含量分别小于3wt.%和1wt.%,而钢渣、赤泥等固体废弃物中的CaO含量超过35wt.％,Fe2O3含量超过10.wt%,限制了这类高钙高铁固废在传统三元陶瓷中的大规模利用。近年来,CaO-MgO-SiO2-Fe2O3-Al2O3 (CMSFA)体系陶瓷(硅钙陶瓷)被证实能够大量利用高钙高铁的原料并且力学性能优良,具有良好的应用前景。但是关于该新型陶瓷体系的烧结过程和致密化机理尚缺乏系统研究,制约了其产业化应用。本文以典型的高钙高铁的钢渣为原料进行利用固废制备硅钙陶瓷材料的研究,利用FactSage软件,X射线衍射技术,扫描电子显微镜,相图等手段对新型的CMSFA陶瓷体系的烧结过程和致密化机理、关键元素铝和铁等对陶瓷烧结过程和性能的影响机理、烧结工艺过程和性能的优化等问题进行了系统的研究,并进一步开展了工业化实验,取得的研究成果如下：(1)根据晶相组成及其对陶瓷物理力学性能的差异,确定了在陶瓷制备的组成范围内CMSFA陶瓷体系的进一步划分准则,即根据陶瓷组分中的氧化镁和氧化铝含量不同,可划分为：①组分中MgO10wt.%时为辉石体系陶瓷,此时主晶相为辉石,烧结温度1180～1220℃,抗折强度90～50MPa；②组分中MgO10wt.%,10wt.5Al2O315wt.%时为辉石-钙长石共存体系陶瓷,此时主晶相为辉石和钙长石,烧结温度1130-1180℃,抗折强度60～100MPa；③组分中MgO5wt.5,Al2O315wt.%时为钙长石体系陶瓷,此时主晶相为钙长石,烧结温度1100～1130℃,抗折强度30～75MPa；④组分中MgO5wt%, Al2O35wt.%时为石英-辉石共存体系陶瓷,此时主晶相为石英和辉石,烧结温度1220-1250℃,抗折强度50-90MPa。(2)铁元素在辉石陶瓷中起到促进致密化和增强晶相两方面的有益作用：在缺少碱金属离子的CMASF体系中,含铁组分具有助熔作用,促进液相形成和致密化进行。同时,部分铁离子在液相烧结阶段固溶进入透辉石相中,使得透辉石转化为性能更加优良的普通辉石相。但是铁元素含量过高不利于陶瓷烧结和性能提升。本研究证实10wt.%的Fe2O3对于辉石体系陶瓷的烧结过程具有促进作用；添加5wt.% Fe2O3样品的抗折强度为132.9MPa,比未添加Fe2O3和添加10wt.%Fe2O3的样品分别提高83.35MPa和68.45MPa。(3)与传统三元陶瓷体系不同,辉石陶瓷体系的烧结过程可以划分为：原料脱水及分解(800℃)、初结晶(700～1100℃)和致密化与二次析晶(1100～1220℃)三个阶段。CaO和Fe2O3组分在辉石陶瓷体系烧结过程中起到了关键作用。不同烧结温度下的样品的XRD和SEM分析表明：CaO在700～1100℃时与粘土和滑石等原料的分解产物生成钙长石、透辉石等,促进了样品在致密化过程之前完成初结晶过程,生成的晶体在后续烧结过程中起到重要的骨架支撑作用；在1150℃时钙铁榴石等含铁组分形成液相促进了样品的快速致密化,并且由于液相的产生促进了二次析品过程的进行,使得制品形成单一的辉石相,有助于力学性能的提升。(4)辉石体系陶瓷的烧结范围比钙长石体系窄,其原因在于液相的生成温度接近于主晶相软化温度,液相量随烧结温度的升高而急剧增加;添加B203助熔剂对改善辉石陶瓷烧结范围的效果最优,添加5wt.%B2O3样品的烧结范围从1200～1220℃降低并拓宽至1100-1150℃,抗折强度仍达到102.5MPa。(5)开展了辉石和钙长石体系陶瓷的工业化生产实验。在陶瓷生产线上成功的制备了以钢渣为主要原料的辉石陶瓷砖,烧结温度1180℃,烧成时间75min,制品的平均抗折强度为93.4MPa,吸水率0.045%,施釉效果良好,表明该体系陶瓷适宜现有的陶瓷工艺,并且具有优良的性能,利于其推广应用。以劣质矿物和尾矿为原料,成功的进行了钙长石体系陶瓷工业化实验,劣质陶土和铝土矿尾矿的掺加量达83wt.%,烧结温度1130℃,烧成时间36min,实现了低温快烧,制品的抗折强度35.2MPa,吸水率0.2%。工业化实验表明,基于钢渣为主要原料所建立的硅钙陶瓷理论体系具有较强的原料适用性和广泛的可推广性,为大量高钙高铁的大宗固体废弃物和低品位矿物在陶瓷工业的高效利用奠定了技术基础。
[Abstract]:The rapid development of industry produces a large amount of solid waste, which not only occupies a large amount of land, but also pollutes the environment, which seriously restricts the sustainable development of the society. Ceramics can not only transform the silicate solid waste of complex chemical components into excellent properties, but also have high added value. On the other hand, the ceramic industry has a large amount of elimination. With the ability to fix the waste, and with the reduction of high quality raw materials and the limitation of natural resource exploitation, the ceramic industry is also faced with the huge demand for the use of low grade minerals or industrial solid waste. Therefore, the preparation of ceramic materials is an effective way to use solid waste. The traditional clay feldspar stone three yuan ceramics belong to the K2O (Na2O) -Al2O3-SiO2 system, The content of CaO and Fe2O3 components is less than 3wt.% and 1wt.%, and the CaO content in solid wastes such as steel slag and red mud is more than 35wt.% and Fe2O3 content exceeds 10.wt%, which restricts the large-scale utilization of this kind of high calcium high iron solid waste in traditional three Yuan Ceramics. In recent years, CaO-MgO-SiO2-Fe2O3-Al2O3 (CMSFA) system ceramics (silica Calcium Ceramics) have been proved to be able to be used. The high calcium and high iron material has good application prospects. However, the sintering process and densification mechanism of the new ceramic system are still lacking systematic research, which restricts the application of its industrialization. In this paper, calcium silicate ceramic materials are prepared by using the typical high calcium and high iron slag as raw materials for the preparation of silica calcium ceramics. By using FactSage software, X ray diffraction, scanning electron microscope and phase diagram, the sintering process and densification mechanism of the new CMSFA ceramic system, the influence mechanism of aluminum and iron on the sintering process and properties of the key elements, the process of sintering and the optimization of sexual energy are systematically studied. The industrialization experiment was carried out step by step. The results obtained are as follows: (1) according to the composition of crystal phase and the difference of the physical and mechanical properties of ceramics, the further division criterion of CMSFA ceramic system in the composition range of ceramics is determined, that is, according to the different content of Magnesium Oxide and alumina in the ceramic components, it can be divided into: (1) MgO10 Wt.% is pyroxene system ceramics, at this time the main crystal phase is pyroxene, the sintering temperature is 1180~1220 degrees C and the flexural strength is 90 ~ 50MPa; (2) the MgO10wt.% and 10wt.5Al2O315wt.% are pyroxene calcium feldspar coexisting ceramics in the composition of the components. At this time the main crystal phase is pyroxene and calcite, the sintering temperature is 1130-1180, and the flexural strength is 60 to 100MPa; (3) MgO5wt.5, Al2O in the components. 315wt.% is calcium feldspar system ceramics, at this time the main crystal phase is calcite, the sintering temperature is 1100~1130 C and the flexural strength is 30 ~ 75MPa; (4) the MgO5wt% and Al2O35wt.% in the component are quartz pyroxene coexisting system ceramics, at this time the main crystal phase is quartz and pyroxene, the sintering temperature is 1220-1250, and the flexural strength 50-90MPa. (2) iron element is in the pyroxene ceramics It is beneficial to promote densification and enhance crystalline phase two. In the CMASF system lacking alkali metal ions, the iron containing components can help melt and promote the formation and densification of liquid phase. At the same time, some iron ions are dissolved into the diopside phase in the phase of liquid phase sintering, making diopside into more excellent ordinary pyroxene. However, the high content of iron is not conducive to the sintering and performance improvement of ceramics. This study confirms that the Fe2O3 of 10wt.% has a promoting effect on the sintering process of the pyroxene system ceramics, and the flexural strength of the 5wt.% Fe2O3 sample is 132.9MPa, and the 83.35MPa and 68.45MPa. (3) and the tradition are higher than that of the samples without Fe2O3 and adding 10wt.%Fe2O3. Different three yuan ceramic system, the sintering process of pyroxene ceramic system can be divided into two stages: raw material dehydration and decomposition (800 degrees C), initial crystallization (700~1100) and densification and two crystallization (1100~1220 C) three stages.CaO and Fe2O3 components play a key role in the sintering process of pyroxene ceramic system. The XRD of samples at different sintering temperatures And SEM analysis shows that the decomposition products of CaO at 700~1100 C and clay and talcum produce calcium feldspar, diopside and so on, which promote the sample to complete the initial crystallization process before the densification process, and the resulting crystal plays an important framework supporting role in the subsequent sintering process, and the formation liquid of iron containing ferric garnet at 1150. The phase accelerates the rapid densification of the samples, and the formation of the liquid phase promotes the progress of the two crystallization process, which makes the product form a single pyroxene phase and helps to improve the mechanical properties. (4) the sintering range of the pyroxene system ceramics is narrower than the calcite system, because the formation temperature of the liquid phase is close to the phase softening temperature of the main crystal. With the increase of sintering temperature, the addition of B203 flux to improve the sintering range of pyroxene ceramics is the best. The sintering range of adding 5wt.%B2O3 samples is reduced from 1200~1220 to 1100-1150, and the flexural strength is still 102.5MPa. (5) in the industrial production experiment of pyroxene and calcium feldspar system ceramics. The pyroxene ceramic tile with steel slag as the main raw material is prepared successfully on the ceramic production line. The sintering temperature is 1180 C and the sintering time is 75min. The average flexural strength of the products is 93.4MPa, the water absorption rate is 0.045% and the glazing effect is good. It shows that the ceramic system is suitable for the existing ceramic technology, and has excellent properties and is good for its application. Inferior quality is poor quality. Minerals and tailings are used as raw materials to successfully carry out the industrialization experiment of calcium feldspar system ceramics. The addition amount of inferior pottery clay and bauxite tailings reaches 83wt.%, sintering temperature is 1130 degrees C, and the sintering time is 36min. It realizes low temperature fast burning, the flexural strength of products is 35.2MPa, water absorption 0.2%. industrial experiment shows that the silicon based on steel slag is the main raw material. The theoretical system of Calcium Ceramics has strong applicability and extensive popularization, which lays a technical foundation for the high efficiency utilization of large amount of high calcium and high iron solid waste and low grade minerals in the ceramic industry.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ174.46

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