用工业废渣制备CBC复合材料基础研究

【作者】 张召述；

【导师】 张宗华；

【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2007， 博士

【摘要】 目前我国工业废渣年产量已达12亿吨，历年累计堆存超过70亿吨，占地6.5亿m²。大量固体废弃物积存，占用土地，污染环境，造成可用资源的流失和浪费。因此，固体废弃物是我国社会经济发展过程中必须着力解决的重大问题。实践表明：传统的填埋、堆存和焚烧处理方法已经不适应资源日渐短缺、环境污染日趋严重的时代要求，必须走资源再生和循环利用的技术路线。经过20多年的发展和积累，我国固体废弃物资源化工作取得了长足进展，废物利用率逐年提高，技术方法日新月异。既有废弃物复合材料、微晶玻璃、硅铝铁合金等废物利用向高技术方向发展的代表性技术；也有水泥基材料、墙体材料、道路工程、矿井回填方面的规模化利用技术，共同实现了综合利用率达到50％的目标。但就总体而言，我国工业废渣利用的瓶颈尚未突破，规模小，技术水平低，效益差的普遍现象没有根本改变。因此，必须开发废物利用效率高、适应性强、效益好的废弃物资源化核心技术。本课题从水泥基材料良好的固体废弃物消纳能力、良好的施工操作性、经济性以及陶瓷材料的优良性能得到启示，首先从工业废渣的共性特征出发，通过对其矿物结构的改变和重组，制备出低温陶瓷胶凝材料，然后利用复合材料原理进行胶凝材料的衍生改性，制备出了一类全新的CBC复合材料。CBC是chemically bonded ceramics的英文简写，表示一种不用高温烧结而采用化学方法固结而成的类陶瓷材料，主要包括MDF、DSP、AAC、RPC等高性能水泥基材料；其中用CBC原理制备的碱激发矿渣水泥以及用偏高岭土制备的土聚水泥因其良好的综合性能备受关注，但依然缺少足够的研究数据。在非硅酸盐水泥体系下，综合采用物理、化学、热力方法使工业废渣如粉煤灰、磷渣、尾矿的原始硅酸盐结构解离活化成为胶凝材料，这种胶凝材料具有传统水泥的施工操作性，但没有高温煅烧和极端苛刻条件，能在水相介质条件下固结成为以硅铝长链为主要结构的类陶瓷体结构（CBC），可用颗粒、纤维、泡沫、聚合物进行复合改性，制备出性能各异的CBC复合材料。这种工业废渣资源化方法目前未见报道，具有创新特征。与传统材料相比：用工业废渣制成的CBC复合材料的基体是化学键合陶瓷，故主要性能比水泥基材料好，可采用混凝土工艺生产，能实现工业废渣的规模化利用；CBC复合材料的制备和形成在接近常温条件下完成，避免了传统水泥和陶瓷生产的高温烧结和废物排放；主要原料为大宗工业废渣，成本低廉，来源丰富，具有显著的环保效益。因此，系统地研究用工业废渣制备CBC复合材料的形成机理、性能和相关因素，不但具有较高的理论和学术价值，而且预期成果将对我国的生态环境良性循环、资源利用永续不衰和可持续发展战略产生积极有益的影响。（一）在本文的研究中，首先探讨了工业废渣的活化机理，分析了废渣的性质，确定了研究方法。研究认为：活化是胶凝材料制备的前提，根据工业废渣的不同性质，需要分别采用物理、化学和热力三类活化方法。（1）物理活化的主要作用是增加颗粒的比表面积，使粘连颗粒分散，产生新生表面，形成表面缺陷，加快活性SiO₂、Al₂O₃的溶出，有利于外部离子的侵入，从而为活性发挥提供前提条件。（2）化学活化主要是通过添加各种碱性激发剂，使聚合度高的硅酸盐网络解聚，进一步生成CSH、CAH、AFt、AFm等物质，但是，在同样的激发条件下，废渣的性质不同，最终生成的水化产物有所区别。碱及碱土金属溶液激发粉煤灰的产物为无定形的铝硅酸盐凝胶和CSH相互交织的硅酸盐网络结构；水玻璃和烧碱激发矿渣的水化产物是水玻璃缩聚产生的硅酸根阴离子与矿渣解聚生成的Ca²⁺、Al³⁺通过缩聚作用生成的针状C-S-H凝胶和矿渣解聚单体重新聚合生成的水化铝酸钙凝胶。偏高岭土与石灰的反应产物为C-S-H凝胶，水化铝酸钙(C₄AH₁₃、C₃AH₆)及水化钙铝黄长石（C₂ASH₆）等。（3）含粘土矿物的煤矸石、尾矿、赤泥，需要采用热力活化，其依据是：粘土矿物是层状结构的铝硅酸盐矿物，在煅烧条件下，其稳定的硅氧四面体和铝氧八面体结构的连接和配位会发生较大的改变，结构中存在断键及活化点，形成偏高岭土。偏高岭土中的原子排列不规则，呈现热力学介稳状态，具有较高的火山灰活性，能与水泥水化产物Ca（OH）₂反应生成水化铝酸钙、水化硅酸钙等胶凝物质。（二）CBC胶凝材料是复合材料衍生的基础，是本文的重点研究内容，按照原料性质的不同，系统研究了粉煤灰、磷渣和尾矿三种体系的CBC胶凝材料。（1）在粉煤灰系CBC胶凝材料中，石灰、烧碱、石膏、硫酸钠、碳酸钠、窑灰均表现出一定的激发效果，单独使用条件下的激发效率低，适合两种或两种以上配合使用，能产生叠加效果，其中CaO-Na₂O的配合最为优异，在此基础上加入碱金属的硫酸盐、氯盐、硅酸盐和有机化产物能起到堵塞毛细孔、抑制泛霜和提高材料稳定性的作用。在粉煤灰和激发体系一定的情况下，水胶比、养护工艺、贮存、原料性质等条件的变化均影响胶凝材料的性能。（2）在磷渣系CBC胶凝材料中，更适合采用SiO₂-Na₂O激发体系，在这一体系下，钠硅比、激发剂掺量、水胶比、表面活性剂和养护条件都能直接影响胶凝材料的性能。（3）在尾矿系CBC胶凝材料中，尾矿需要首先煅烧，在SiO₂-Na₂O激发体系下，尾矿的热处理条件、激发剂性质均是重要的影响因素；活化尾矿与矿渣、粉煤灰等进行复配，能产生减水、助磨和增强作用。（4）XRD显示，粉磨只改变粉煤灰颗粒的形貌，不能改变它的矿物结构；经蒸压处理后的粉煤灰系CBC胶凝材料水化产物有硅酸二钙、硅铝酸钙，不存在硅酸盐水泥的水化产物水化硅酸钙、氢氧化钙和钙矾石凝胶，也没有探测到其它Na⁺物质的衍射峰，说明水化产物是一些无定型的硅铝酸盐。磷渣系CBC胶凝材料的固结体除主要保持磷渣的基本属性外，新生了衍射峰强度大的水化硅酸钙和碳酸钙矿物，其中水化硅酸钙是由磷渣玻璃体解离重组以及磷渣解体释放的Ca（OH）₂与活性SiO₂进行缩聚生成。尾矿系CBC胶凝材料的固化产物主要是一些长链的铝硅酸盐，是煅烧尾矿中的活性硅铝在碱性条件下，经过水化、重排、离子交换、缩聚生成Si-O-Si和Si-O-Al为主的长链结构，因此表现出优良的物理力学性能和耐腐蚀性。（5）SEM显示，三种CBC胶凝材料的固结体结构致密，和骨料之间没有明显界面，这也是力学性能好，吸水率低的原因之一。（三）在CBC胶凝材料基础上，本文对颗粒增强的CBC复合材料以及高分子聚合物改性的CBC—PM复合材料制备机理进行了基础性研究。（1）在颗粒强化的CBC复合材料中，影响材料性能的主要因素有胶凝材料的性能，胶骨比，骨料种类，用水量，成型条件和养护工艺。研究表明：在磷渣、尾矿、粉煤灰三类CBC胶凝材料中，可用20—60％的磷渣、矿渣、铜渣、石英砂、废玻璃等矿物等量替代粉煤灰；可用铸造废砂、磷渣、石英砂、炉渣为骨料；添加减水剂和表面活性剂可改善基体与骨料的界面状况，降低需水量，从而改善材料的性能；可采用压制和浇注成型，但一般情况下，压制成型工艺制备的材料性能更好；CBC复合材料适合湿热养护，温度越高，需要的养护时间越短，在合理的工艺条件下，可以制备出抗压强度大于100MPa的高强度复合材料。（2）用不同性质的高分子聚合物对颗粒强化的CBC复合材料改性具有不同的适应性：苯丙乳液对磷渣系CBC复合材料的改性效果十分明显，能提高生坯的凝结硬化速度和抗折强度、降低吸水率。用热塑性废塑料对CBC复合材料改性，能获得一种连续相是CBC，分散相是聚合物的新型CBC-PM复合材料，在这种复合材料中，胶骨料、聚胶比、塑料形态、含泥量、养护工艺都直接影响材料的性能。最终形成的CBC-PM复合材料具有陶瓷和高分子材料的综合性能，耐酸碱，耐水热，耐冲击，可代替木材使用。（四）技术经济分析表明：CBC复合材料具有优良的物理力学性能和稳定性、抗渗耐冻、耐腐蚀、耐高温、耐水热，可广泛替代水泥基材料、陶瓷材料、石材、高分子聚合物、金属材料使用。CBC复合材料制备过程简单，几乎没有二次废物排放，符合国家节能环保的产业政策，能适合众多工业废渣的资源化利用，预期的社会、经济和环境效益十分显著。更多还原

【Abstract】 At present, the annual output of industrial waste residues has reached 1.2 billion tons and the total accumulation is more than 7 billion tons, covering 6.5 hundred million square meter filed, with comprehensive utilization rate 52%. Large accumulation of solid waste is not only taking up land, polluting environment, but also causing wastage of available resources. Thus, solid waste is the major issue that must be made to resolve in our socio-economic development process. Practice shows that, some waste disposal methods such as traditional landfill, storage and incineration have not been suitable for the growing shortage of resources and environmental pollution times and we must follow renewable resources and recycling technologies routes.After about 20 years of development and accumulation, the solid waste resource cause in our country has made certain progress, with growing waste utilization rate and rapid changing technological methods. The target that the rate of comprehensive utilization of industrial waste residue had achieved 50% in "10th Five-Year Plan" through both the representation technology developing to the high-tech direction of waste composite materials, microcrystalline glass, light materials, silicon and aluminum ferroalloy and the large scale waste use of technology such as cement base materials, wall materials, road works, pit backfill. But on the whole, the bottlenecks of technology has not been breakthrough and the facts that small scale, low level of technology, inefficient universal has not been fundamentally changed. Therefore, we must develop the core technology of waste resources recovery that possess recycling efficient, adaptable and good economic returns.According to the inspiration that cement base material is provided with good capacity for accepting the solid waste, favorable operation, low cost and the choiceness performance of ceramics , a low-temperature ceramics cement should be produced with industrial waste residues through changing its mineral structure and reorganization firstly , and a new kind of CBC composite material could be prepared according to the the principles of waste resource composite materials through derived from cement.CBC is abbreviation for Chemically Bonded Ceramics, first proposed by Professor D. Roy, referring to a kind of ceramics material not need to be sintered by high-temperature but to concreted through chemical method, mainly including MDF, DSP, AAS three high-performance cement materials. Academician Zhongwei Wu further elaborated the development prospects of these types of materials, and initiated the PC, RPC, HPC. On the basis of the development, scholars of Qinghua University and South China University of Technology had a keen interest in Geopolymer cement material produced with kaolin invented by J. Davidovits, and conducted with some research and reports, but rarely see related research data.In the non-silicate cement system, taking comprehensive physical, chemical, thermal methods to make the original silicate structures of industrial waste residues such as fly ash, phosphorus slag, tailings unbind and activate to become cement materials, this cement was provided with traditional cement operational performance , consolidating under the conditions of water medium to form a ceramic body structure （CBC） mainly in the structure of long silicon and aluminum chain , not need to sinter at high temperature and no extremeness rigor technics conditions . It is easy to produce vary performances of the CBC composite materials derived from cement with particles, fibers, foams, polymers. This method of industrial waste residues resource recovery has not been reported by others , so it is in original innovative features .Compared with traditional materials: the matrix of CBC composite materials produced by industrial waste residues is chemical bond ceramics, so its main performance is superior to concrete based cement. It could be generated in concrete production processes and utilized industrial waste residues at a large scale . CBC composite material is produced and developed in close to normal temperature atmosphere, avoiding the high temperature sintering and waste emissions in traditional cement and ceramics production. The main raw materials are bulk of industrial waste residues, low-cost, rich sources with significant environmental benefits. Therefore, the systematic study of formation mechanisms, performance and related factors of CBC composite materials produced by industrial waste residues, not only have higher theoretical and academic value, but also be good for virtuous circle of our ecological environment, sustainable use of resources development strategy .In this research, the activation mechanisms of industrial waste residues was explored, the nature of waste residues was analyzed and the study method was identified. Research shows that different kinds of activation methods must be required according to the nature of industrial waste residues , and mainly sum up physical, chemical and heat treatment.1) The primary role of physical activation is to increase of the particle surface ,make conglutinate particles scattered , produce new surface, form surface errors and accelerate the elution of reactive SiO₂, Al₂O₃ , which is good for making the external ion penetrated, and provided a prerequisite for active play.2) The primary role of Chemical activation is to make the high degree of convergence silicate network depolymerization generate CSH, CAH, AFt, AFm through the addition of various alkaline catalyst , the hydration substance different from nature of waste residue even in the same inspired conditions. The offspring of fly ash stimulated by alkali and alkali earth metal solution is amorphous aluminum silicate gel and CSH weaving silicate network structure. The hydration substance of slags which was stimulated by sodium hydroxide and water glass were needle shaped C-S-H gels and hydrate calcium aluminum gels. Needle shaped C-S-H gels are generated by condensation polymerization between silicic acid anions which was generated by condensation polymerization of water glass and Ca²⁺, Al³⁺ generated by slag depolymerization . Hydrate calcium aluminum gels are generated by re-gather of monomers which resulted from slag depolymerization. The hydration substance of metakaolin were C-S-H gels, C₄AH₁₃, C₃AH₆) and C₂ASH₆ activated with lime.3) Heat activation need to be adopted to coal gangue, tailings, and red mud because they contained clay minerals. The theory basis is that clay mineral is Stratiform structure aluminium silicate mineral, under the calcine conditions, the link and allocation of stability silicon oxygen tetrahedron structure and aluminium oxide octahedron structure will occur larger change. The existing broken bond and action spot to form metakaolin. The configuration of metakaolin atomic is irregular, presenting thermodynamic metastable state and possessing higher eruption reactive, and it could reacted with Ca（OH）₂convertted from cement and generate new glue substances such as hydration calcium aluminum, hydration calcium silicate,.CBC cement material is the basic of composite materials and its preparation is the focus study in this paper. According to the different natures of waste, three systems CBC cement materials including fly ash, phosphorus slag and tailings were studied systemically.1) In the system of fly ash CBC cement, lime, sodium hydroxide, gypsum, sodium sulfate, sodium carbonate, flue ash have all shown some inspired effects. The stimulate effect was better when two or more mixed than single. Especially it would get a significant mutual stacking effect when lime and sodium hydroxide were mixed at a certainly proportion. On this basis, the way that addition to the potassium aluminium sulphate, ferric chloride, sodium silicate, amphetamine-tanks latex, stearic acid calciutm which plays a role of improving intensity, plugging pore and suppressing float frost. In certain inspired system circumstances, the conditions of ratio of water and glue, conservation, storage, and changings of raw material would affect the performances of CBC cement.2) In the system of phosphorus residue CBC cement, Na₂O-SiO₂ inspired system was more suitable. In this system, module of water glass, the amount of excitated agent, ratio of water and glue, surface active agent and conservation conditions could directly affect the performance of cement .3) In the system of tailings CBC cement, tailings need to be calcine firstly, , the heat treatment conditions of tailings, the modules and the dosage of water glass both were important factors in the excitated system of Na₂O-SiO₂. Better effects could be produce if mixed with slag or fly ash in tailings, and this CBC cement was more suitable concreted in vapor pressure.4) XRD shows that, mechanical milling could only change externalities of fly ash particles but not change its mineral structure. The main mineral characteristics of fly ash has no significant changes when the CBC cement of Na₂O-CaO- fly ash was maintained in 0. 5MPa steam pressure for eight hours, and there were two neonatal hydration products include calcium silicic acid and calcium aluminosilicate , and there were not hydrate silicate calcium, calcium hydroxide and Aft gels which generated from Portland cement, also hydrate sodium silicate , hydrate sodium aluminium and other Na⁺ salt were not detected by diffraction peak . All above facts indicated that the hydrate substance were unformed aluminosilicate. The hydrate substance of phosphorus residue CBC cemenIn were hydrate calcium silicate and calcium carbonate and the main basic attributes of phosphorus slag had not changed, In this system, hydrate calcium silicate was generated by Ca （OH）₂ released from phosphorus residue reacted with water glass and reorganization and condensation polymerization of unformed hydrate silicate separated from phosphorus residue . The hydrate substance of tailings CBC cement were mainly long chain aluminum silicates formed from the active SiO₂, Al₂O₃ generated in the process of sintered reacted with alkaline excitated agent , Si-O-Si and Si-O-Al silicate structure generated after through hydration, recomposition, ion exchange, condensation polymerization. Therefore, it shown good physical mechanics and resistant corrosive performance.5) SEM reveals that the concreted body structure of three CBC cement is compact, there is no clear interface between aggregate and cement, which is one of the reasons why they are provided with good mechanics performance and low water absorption rate. On the basis of CBC cement, the preparation mechanism of particle enhanced and polymers modified CBC composite materials have been studied basically.6) The main factors affecting the performance of CBC composite materials were the performance of CBC cement, aggregate species, ratio of gels and aggregate, ratio of water and cement, molding conditions and conservation processes in the particles strengthen system. Studies show that, in the systems of phosphorus slag, tailings and fly ash CBC cement, it was available to equivalent substitute 25-30% of the phosphorus slag, slag, copper slag, quartz sand, glass and other mineral for active powder such as fly ash. The casting tailings, phosphorus slag, quartz sand, slag could be used as aggregate. The interface situation of basal body and aggregate could be improved by adding water reducing agent and surface active agent and lead to improve the performance of composite materials through reducing water consumption. Either pressed or cast shaped craft was practicable, but normally, press shaped craft could produce better performance. CBC composite materials were suitable for conservation in the hot and damp condition, the higher the temperature was, the shorter time required. It could produce high-intensity composite materials with compressive strength of more than 100MPa under the condition of reasonable technological parameters.7) The effects of polymers differ from the systems of CBC composite materials enhanced with particle. The modifying effect of amphetamine-tanks latex to the system of phosphorus residue CBC composite materials was obvious, it could condense the time of concretion , significantly improve the bending intensity and reduce the rate of water absorption. A new CBC-PM composite materials whose continuous phase was CBC and scattered phase was polymer could be formed modified with thermoplastic waste plastic in the condition of steam pressure conservation. In this composite materials, these parameters such as ratio of glue and aggregate, ratio of glue and polymer, configuration of plastic, quantity of mud and conservation craft directly affect the performance of composite materials. The CBC-PM composite materials was provided with the performances of ceramics and macromolecular for example corrosion resistance, enduring heat hot and high impact, and could be used as wood.8)Techno-economic analysis shows that , CBC composite materials was provided with excellent physical mechanics performance and stability, enduring sink and freezing, corrosion resistance, withstand high temperatures and enduring heat hot, which could be used widely to replace concrete, ceramics, stone, macromolecular polymers, and metal materials. The manufacture process of CBC composite materials was simple and almost no secondary waste emissions, which is consistent with the national industries policy of energy and environmental protection and fit for the resources recovery of so many industrial waste residues. The expected social, economic and environmental benefits will be significant.更多还原