改性脱硫灰渣对水泥性能和微观结构的影响研究

发布时间：2018-04-03 01:21

本文选题：脱硫灰渣　切入点：水泥混合材　出处：《成都理工大学》2015年硕士论文

【摘要】：随着循环流化床脱硫技术的迅速发展,产生的脱硫灰渣量急剧增加,我国2013年的产量约8000万吨。目前,这种灰渣还主要以堆放的方式处理,资源化再利用迫在眉睫。脱硫灰渣属烧结粘土类物质,具有火山灰活性,可以作水泥混合材来使用。水泥行业对混合材需用量大,将脱硫灰渣大量应用于水泥混合材生产,对于资源再利用和环境保护具有重要的意义。由于脱硫灰渣中的游离氧化钙(f-Ca O)和SO3含量较高,将其大量用作水泥混合材时,水泥的蒸压膨胀值较大,安定性不合格。针对这些问题,本文以茂名石化动力厂的循环流化床脱硫灰渣为研究对象,重点对脱硫灰渣的基本性质,加水量、改性剂种类、粉磨时间、消解温度等因素对脱硫灰渣中f-Ca O的消解效果及对其微观结构的影响,改性脱硫灰渣配制的水泥性能和微观结构变化这三方面进行了研究,完成的主要工作及得出的结论如下。对脱硫灰渣的基本性质进行了详细研究。结果发现,茂名石化循环流化床脱硫灰渣的微观形貌不规则,表面粗糙且疏松多孔,颗粒的粒径级配不合理,79.50%的粒径≥65μm,中间粒径(D50)达到113.67μm。总Ca O含量为23.07%,其中f-Ca O为8.49%左右,与普通粉煤灰相比,这种灰渣含有特征的矿物组分Ca SO4和Ca O。随脱硫灰渣中SO3和f-Ca O含量增加,灰渣的自硬性强度和活性指数均先增加后减小,线性膨胀率则一直增大。对影响脱硫灰渣改性效果的因素进行了系统研究。实验表明,改性过程中影响脱硫灰渣f-Ca O含量的主要因素是加水量,其次是改性剂种类、消解温度、消解时间、粉磨时间等。当加水量为30%时,消解1d后,f-Ca O含量降到2.81%;加入1%的以硫酸钠为主的复合改性剂B和30%的水,在45℃条件下密闭养护8h后,脱硫灰渣中f-Ca O含量降到2.04%。改性后的脱硫灰渣的蒸压膨胀值减小到2μm左右,3d自硬强度的活性值由78.28%增加到82.35%,28 d的自硬强度活性值由80.69%增加到84.89%。未改性的脱硫灰渣生成的Ca(OH)2覆盖在灰渣的表面,呈现六方板状;加入1%以硫酸钠为主的复合改性剂B和以三乙醇胺为主的复合改性剂C,粉磨15 min后于40℃养护1 d,其脱硫灰渣颗粒表面生成的Ca(OH)2晶体呈簇状向外生长,扦插在空隙之中,同时颗粒表面生成了絮状物质,灰渣表面结构得以改善。对脱硫灰渣配制的水泥性能和微观结构的变化进行了详细考察。实验发现,与掺加30%未改性的脱硫灰渣水泥相比,掺加30%改性后的脱硫灰渣的水泥,水灰比从原来的0.3045降为0.285,初、终的凝结时间明显加快,蒸压膨胀值由0.5248 mm减小为0.2789 mm,胶砂强度后期发展明显,抗压活性比由7d的77.06%增加到28 d的94.01%。水泥净浆试块水化3 d和28 d的SEM图和XRD谱图表明,改性剂B改性的灰渣配制的水泥,其水化进程加快,钙矾石形成提前,水化28 d后大块的氢氧化钙(CH)基本消失,水化硅酸钙(C-S-H)凝胶与钙矾石(AFt)的结合更加紧密,水化后的密实度明显增加。改性后的脱硫灰渣,活性值增大,有害组分含量减少,可作为水泥混合材而大量使用。当其掺量达到30%左右时,水泥的各项性能指标均满足美国材料化学学会标准(ASTM C)的要求。
[Abstract]:With the rapid development of circulating fluidized bed desulfurization technology, desulfurization ash production increased dramatically, China's 2013 production of about 80 million tons. At present, the main way to ash pile treatment, reuse is imminent. Desulfurization ash sintered clay material, with volcano activity, can be used as cement admixture the mixed material of cement industry. A large amount of desulfurization ash will need, widely used in cement production, has an important significance for the reuse of resources and environmental protection. Because of free calcium oxide in the desulfurization ash (f-Ca O) and higher SO3 content, the amount used as cement admixture, cement Autoclave Expansion larger, stability unqualified. To solve these problems, this paper takes the circulating fluidized bed desulfurization ash of Maoming petrochemical power plant as the research object, focus on the basic properties of desulfurization ash water amount, modified Agent, grinding time, digestion effect factors digestion temperature on desulfurization ash in f-Ca O and its effect on the microstructure of modified cement properties and microstructure changes of preparation of Desulfurization Residues in these three areas were studied, the main work and conclusions are as follows. On the basic properties of desulfurization ash a detailed study. The results showed that the morphology of Maoming Petrochemical circulating fluidized bed desulfurization ash is irregular and rough surface and porous particle size grading is not reasonable, 79.50% of the size of more than 65 m, middle diameter (D50) reached 113.67 M. total Ca O content is 23.07%, which is about 8.49% f-Ca O, compared with ordinary fly ash, mineral composition and features of this ash containing Ca SO4 and Ca O. with SO3 f-Ca and O content of desulfurization ash increase in ash from the rigidity strength and activity index were increased first and then decreased, linear expansion rate is always Increased. Influence factors of desulfurization ash modification effect were studied. Experimental results show that the modified process of main factors affecting the desulfurization ash content of O f-Ca is the amount of water, followed by the type of modifier, digestion temperature, digestion time, grinding time. When the water content is 30%, digestion after 1D. F-Ca O was reduced to 2.81%; adding 1% with sodium sulfate based compound modifier B and 30% water, under the condition of 45 DEG C in airtight curing 8h, the f-Ca O content of desulfurization ash dropped to 2.04%. modified desulfurization ash after Autoclave Expansion decreases to about 2 m, 3D strength activity increased from 78.28% to 82.35%, 28 d from the hard strength activity increased from 80.69% to 84.89%. is not modified desulfurization ash generative Ca (OH) 2 covered in ash surface, showing the six plate; adding 1% with sodium sulfate based compound modifier B and composites with triethanolamine based Agent C, grinding after 15 min at 40 DEG C for maintenance of 1 D, the desulfurization ash particles formed on the surface of Ca (OH) 2 Crystal clumps of outward growth, cutting in the gap, while the particles formed on the surface of flocculent material, ash can be improved. The changes of surface structure properties of cement preparation and microstructure of desulfurization ash were investigated in detail. The experimental results showed that, compared with adding 30% unmodified cement of desulfurization ash, modified desulfurization ash after adding 30% of cement, water cement ratio decreased from 0.3045 to 0.285, at the beginning of the final setting time significantly accelerated the autoclave expansion value decreases from 0.5248 mm to 0.2789 mm, the late strength development is obvious, the compressive activity ratio increased from 77.06% 7d to 28 d 94.01%. cement test block water 3 D and 28 d SEM and XRD spectra indicated that compound modifier B modified slag cement, the hydration process accelerated, ettringite formation in advance, water 2 After 8 d chunks of calcium hydroxide (CH) disappeared, calcium silicate hydrate (C-S-H) gel and Ettringite (AFt) combined with more closely, density of water after modified desulfurization ash increased significantly. After the activity increases, reduce the content of harmful components, can be used as cement admixture and a large number of use. When its content reaches about 30%, the performance index of cement can meet the American Institute of chemical materials standard (ASTM C) requirements.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1

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