高件能煅烧高硅磷石膏基水泥的制备与性能研究

发布时间：2018-06-04 14:54

本文选题：磷石膏 + 水硬性胶凝材料　；参考：《昆明理工大学》2015年硕士论文

【摘要】：磷石膏是工业湿法生产磷酸的副产物,其主要成分为CaSO4·2H2O,并含有P2O5、F-、有机物、微量重金属以及其他的一些杂质。目前,在全球范围内,大约有15%的磷石膏作为资源被回收利用,主要应用在农业、建材业和水泥缓凝剂等方面,但是,仍有85%的磷石膏作为固体废物被堆放处理,不仅占用土地资源,而且会对周围的环境造成严重的污染。经过国内外学者多年的研究,多集中于将磷石膏作为石膏板等石膏建材和磷石膏制硫酸联产水泥工艺。磷石膏制硫酸联产水泥工艺能将磷石膏变废为宝,用于生产水泥熟料和硫酸,不但能够大批量地利用磷石膏,减少其堆积和污染,而且能够减少对石灰石原料和硫矿资源的开采,具有一定的环境和社会效益。但是在使用该工艺时,也存在着明显的不足,在技术和经济效益方面还有许多问题亟待解决。从国内外建成的磷石膏制硫酸联产水泥工艺的生产线来看,主要存在着以下几个方面的问题：一是磷石膏所含杂质较多,原料成分变动较大,不易工业中的生产控制；二是熟料烧成温度高,系统能耗大,回转窑中容易结圈、粘结甚至堵塞,影响工艺的正常运行；三是生产出的熟料安定性差,质量不稳定。为了降低利用磷石膏烧制水泥熟料的能耗,解决磷石膏的分解和熟料的烧成等问题,本论文以磷石膏、活性炭和粉煤灰为主要原料,在1200℃低温煅烧(相对于熟料的烧成温度1450℃)的条件下,按照一定的配比进行混合煅烧,再将煅烧后的试样同纯硅酸盐水泥熟料进行混合,制备出一种高性能煅烧高硅磷石膏基水泥。在煅烧过程中,磷石膏的分解产物CaO与粉煤灰中的SiO、Al2O3、Fe2O3等活性物质反应生成各种有助于提高其硬化浆体强度的硅酸盐矿物和铝酸盐矿物。适量的碳组分有助于在煅烧过程中形成还原气氛,促进磷石膏的分解,而部分未分解的CaSO4还可以充当水泥缓凝剂,减少或不用外掺天然石膏,不但能够提高水泥的强度,还能够节约资源,带来经济效益。本论文采用正交试验的方法对制备高性能煅烧高硅磷石膏基水泥进行了探索研究。由于低温煅烧制备磷石膏基水硬性胶凝材料中的矿物组成同普通硅酸盐水泥熟料中的矿物组成存在着一定的差异,故在本正交试验中以水硬系数(HM)来代替石灰饱和系数(KH)作为生产控制指标。在正交试验中,以煅烧温度、保温时间、活性炭掺量和HM作为正交试验的四个因素,对高性能煅烧高硅磷石膏基水泥的反应条件进行了研究。结果表明,当煅烧温度为1200℃、保温时间为30min、活性炭掺量为10%以及HM为13时,高性能煅烧高硅磷石膏基水泥的早期强度和后期强度都较高。在实际工业生产中.可以将HM作为主生产率值,SM作为辅助率值。本论文对正交试验中抗压强度典型试样进行了XRD分析。结果表明,抗压强度较高的试样中普遍存在的活性矿物有硅酸三钙(C3S)、硅酸二钙(C2S)、铝酸三钙(C3A)、铝酸二改(C2A)和钙铝黄长石(C2AS)等。其中,C3S和C3A的水化速度较快,对于硬化浆体的早期强度有着显著的贡献；在低温煅烧条件下生成的 C2S,活性较高.水化速度正常,对于硬化浆体的早期强度和后期强度都有着较大的促进作用；C2A和C2AS属于弱水硬性矿物,水化较慢,对于早期强度的提升无明显贡献,但对于后期强度有着一定的促进作用。本论文还通过XRD、SEM和EDS微观分析手段对高性能煅烧高硅磷石膏基水泥的水化产物进行了研究分析。结果表明,硬化浆体主要由Ca(OH)2、C-S-H凝胶、水化钙铝黄长石(C2ASH8)、钙矾石(AFt)以及水化氧化铝凝胶组成,在整个结构中,以AFt作为网状骨架,其中填充了大量的C-S-H凝胶和水化氧化铝凝胶,形成了致密的结构,使得水泥的宏观表现为抗压强度高。本论文模拟了实际工业生产中的情况,采用等温法对磷石膏—活性炭—粉煤灰体系进行了热分解反应动力学的研究。将S03含量作为分解率的评价标准,对磷石膏—活性炭—粉煤灰体系的指前因子和表观活化能进行了计算,确定了该体系的最概然机理函数。结果表明,磷石膏—活性炭—粉煤灰体系分解的表观活化能为313.78～338.42KJ·mol-1,指前因子1nA为22.22～24.10s-1,最概然机理函数为代表随机成核和随后生长性质的Avrami-Erofeev方程(n=2)。本论文对煅烧制备高性能煅烧高硅磷石膏基水泥时产生的烟气量及其烟气中SO2的含量进行了分析计算,并提出了一个合理的回收方案。结果表明,在煅烧制备高性能煅烧高硅磷石膏基水泥时,每生产1kg的熟料产生的烟气量为1.11Nm3/kg,其中SO2的浓度为14.95%；同时通过分析表明,湿法有机胺脱硫技术,是一种新兴的绿色烟气脱硫工艺,其脱硫剂的循环再生利用,不但对环境的二次污染较少,而且能降低运营中的成本,设备简单,操作流程简便,具有较高的经济合理性和技术可行性,可以作为回收处理煅烧制备高性能煅烧高硅磷石膏基水泥时产生的SO2的方法。本论文针对了磷石膏目前难以得到有效资源化利用的现状,提出了一种在低温煅烧的条件下,制备高性能煅烧高硅磷石膏基水泥的方法。该法具有能耗低、设备简单、操作简便的特点,克服了传统磷石膏制硫酸联产水泥工艺中的种种不足,并从微观和动力学角度阐释了高性能煅烧高硅磷石膏基水泥高强的来源,完善了其制备的理论基础,为下一步进行工业化应用和推广奠定基础。
[Abstract]:Phosphogypsum is a by-product of phosphoric acid production by industrial wet process. Its main component is CaSO4 2H2O, and contains P2O5, F-, organic matter, trace heavy metals and some other impurities. At present, around 15% of phosphogypsum is recycled as a resource worldwide. It is mainly used in agriculture, building materials industry and cement retarder. 85% of phosphogypsum is stacked as solid waste, not only occupying land resources, but also causing serious pollution to the surrounding environment. After years of research by scholars at home and abroad, most of them have concentrated phosphogypsum as plasterboard gypsum materials and phosphogypsum to produce sulphuric acid cement. The process of phosphogypsum to produce sulphuric acid cement can make phosphorus Gypsum is used in the production of cement clinker and sulfuric acid. It can not only use phosphogypsum in large quantities, reduce its accumulation and pollution, but also reduce the mining of limestone raw materials and sulphur resources. However, there are also obvious deficiencies in the use of the technology and the technical and economic benefits. There are many problems to be solved urgently. From the production line of phosphogypsum made by phosphogypsum made at home and abroad, there are main problems in the following aspects: one is that the impurities in the phosphogypsum are more, the composition of the raw material is changed, the production control in the industry is not easy, and the two is the high temperature of the clinker, the large energy consumption of the system and the rotation of the system. In the kiln, it is easy to ring, bond and even clog, which affects the normal operation of the process. Three is the poor stability and unstable quality of the produced clinker. In order to reduce the energy consumption of the cement clinker by using phosphogypsum, solve the decomposition of phosphogypsum and the burning of clinker, this paper uses phosphogypsum, activated carbon and fly ash as the main raw material, at 1200 C Under the conditions of low temperature calcining at a temperature of 1450 degrees centigrade, the calcined calcined samples were mixed with pure Portland cement clinker, and a high performance calcined high silicon phosphogypsum based cement was prepared. During the calcining process, the decomposed product CaO of phosphogypsum and SiO, Al2O3, Fe in the fly ash 2O3 and other active substances react to all kinds of silicate minerals and aluminate minerals that help to improve the strength of their hardened pulp. Proper amount of carbon components can help to form a reduction atmosphere during the calcination process and promote the decomposition of phosphogypsum, while some of the undecomposed CaSO4 can also act as a cement retarder, reducing or not adding natural gypsum. Not only can it be used to reduce or do not use natural gypsum. In this paper, the preparation of high performance calcined high silicon phosphogypsum based cement was studied by orthogonal test. The mineral composition of the phosphogypsum based cementitious material and the mineral composition in the common portland cement clinker by low temperature calcination was studied in this paper. In this orthogonal test, the water hardness coefficient (HM) is used to replace the lime saturation coefficient (KH) as the production control index in this orthogonal test. In the orthogonal test, the reaction conditions of high performance calcined high silicon phosphogypsum based cement are studied with calcining temperature, holding time, active carbon content and HM as four factors of orthogonal test. The results show that when the calcining temperature is 1200, the holding time is 30min, the amount of activated carbon is 10% and the HM is 13, the early strength and the later strength of high performance calcined high silicon phosphogypsum cement are high. In the actual industrial production, the HM can be used as the main productivity value and SM as the auxiliary ratio. The paper is typical of the compression strength in the orthogonal test. The samples were analyzed by XRD. The results showed that the common active minerals in the specimens with high compressive strength were three calcium silicate (C3S), two calcium silicate (C2S), three calcium aluminate (C3A), aluminum acid two (C2A) and calcium aluminum yellowish feldspar (C2AS). Among them, the hydration speed of C3S and C3A was faster, and the early strength of the hardened slurry was significantly reduced. The C2S produced under the temperature calcining condition has higher activity and normal hydration speed, which has a great promotion effect on the early strength and late strength of the hardened slurry; C2A and C2AS belong to the weak water hard mineral, and the hydration is slow, it has no obvious contribution to the early strength, but it has a certain promotion effect on the later strength. The hydration products of high performance calcined high silicon phosphogypsum based cement are studied by XRD, SEM and EDS microanalysis. The results show that the hardened slurry is composed mainly of Ca (OH) 2, C-S-H gel, calcium aluminum Huang Changshi (C2ASH8), ettringite (AFt) and hydrated aluminum oxide gel. In the whole structure, AFt is used as a reticular skeleton. A large number of C-S-H gels and hydrated alumina gel are filled to form a compact structure, which makes the macroscopic performance of the cement with high compressive strength. This paper simulates the situation in the actual industrial production and studies the kinetics of the thermal decomposition reaction of the phosphogypsum active carbon fly ash system by isothermal method. The content of S03 is taken as the decomposition of the system. The pre index and apparent activation energy of phosphogypsum active carbon fly ash system are calculated and the most probable mechanism function of the system is determined. The results show that the apparent activation energy of the decomposition of phosphogypsum active carbon fly ash system is 313.78 ~ 338.42KJ. Mol-1, the former factor 1nA is 22.22 ~ 24.10s-1, and the most probability is the most probability. The mechanism function is the Avrami-Erofeev equation (n=2), which represents the random nucleation and the subsequent growth properties. In this paper, the amount of flue gas and the content of SO2 in the flue gas produced by calcining high performance high silicon phosphogypsum based cement are analyzed and calculated, and a reasonable recovery scheme is put forward. The results show that the high performance calcinations are prepared by calcining. When high silicon phosphogypsum based cement is burned, the amount of flue gas produced by the clinker produced by 1kg is 1.11Nm3/kg, and the concentration of SO2 is 14.95%. At the same time, the analysis shows that wet organic amine desulphurization technology is a new green flue gas desulfurization technology. The recycle utilization of the desulfurizer not only reduces the two pollution of the environment, but also reduces the transport of the desulfurizer. The cost, simple equipment, simple operation process, high economic rationality and technical feasibility, can be used as a method to produce high performance calcined high silicon phosphogypsum based cement, which is produced by calcining and calcining. This paper aims at the present situation that phosphogypsum is difficult to be used in the utilization of phosphogypsum at present, and a kind of SO2 is put forward at low temperature. The high performance calcined high silicon phosphogypsum based cement is prepared under the conditions of calcining. This method has the characteristics of low energy consumption, simple equipment and easy operation. It overcomes the shortcomings of the traditional phosphogypsum system of sulphuric acid producing cement, and explains the source of high performance calcined high silicon phosphogypsum cement high strength from the micro and dynamic angles. The theoretical basis of its preparation is well established, laying the foundation for further industrial application and popularization.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1

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