【作者】 栾敬德；

【导师】 李爱民；

【作者基本信息】 大连理工大学 ， 能源与环境工程， 2010， 博士

【摘要】 随着化石燃料过度利用引起的资源枯竭问题日益严峻,寻找可替代能源已成为世界各国亟待解决的问题。在众多的替代能源中,储量丰富的油页岩资源引起了各国专家的广泛关注。油页岩是一种灰分含量大(约为70wt%～90wt%)的低热值固体燃料。按其灰分含量计算,油页岩可采资源全部利用将产生页岩灰渣1702.8～2189.2亿吨,若油页岩资源全部利用将产生2879.8～6479.5亿吨。随着油页岩的大力开发利用,年产量巨大的页岩废渣带来的环境污染问题已受到人们关注。页岩废渣含有酸性和碱性物质,尤其是重金属,通过地表和地下水体径流、悬浮飘尘污染周围土地、水域和大气,其潜在危害不容忽视。因此,页岩废渣的安全处理是油页岩工业发展亟待解决的问题。本研究选取油页岩及其循环流化床燃烧形成的飞灰为研究对象,通过对两者重金属赋存形态及含量分析,发现在燃烧过程中重金属的迁移转化规律；针对飞灰中重金属富集情况,提出飞灰处理注意事项,并采用熔融—烧结方法进行飞灰处理制备成微晶玻璃,其具体内容如下所示：(1)采用Tessier五步连续提取法,通过对油页岩和页岩飞灰中重金属Cu、Cr、Ni、Cd、Pb、Zn的不同赋存形态含量的测定,研究重金属在页岩飞灰中的富集程度。采用主成分分析方法,研究循环流化床燃烧前后重金属的形态迁移转化规律,并采用STI模型进行页岩飞灰中重金属毒性评估计算。研究表明：页岩飞灰富集重金属Cu、Cd、Pb、Zn,其中Pb、Zn富集量高达117.02μg g-1、71.06μg g-1；页岩飞灰中铁锰氧化态和可交换态重金属含量显著增加,致使飞灰生态风险性增强。(2)采用机械筛分方法,对页岩飞灰样品进行粒度分布分析。在考察页岩飞灰化学组成和传统灰渣处理工艺利弊的基础上,阐明采用熔融工艺处理页岩飞灰的可行性和优越性。在引入氧化钙添加剂的条件下,配制了五种不同碱度的玻璃原料,经熔融后水淬处理使玻璃原料形成玻璃质熔渣,然后经核化和晶化处理将其制备成微晶玻璃。在微晶玻璃熔制过程中,考察碱度和热处理时间对微晶玻璃性能指标的影响,为灰渣微晶玻璃生产提供科学依据。(3)物理化学特性分析表明页岩飞灰颗粒细小,富含SiO2、Al2O3、CaO等多种碱金属氧化物,是熔制CaO-Al2O3-SiO2三元相系微晶玻璃的良好原料。在玻璃原料熔融处理过程中,体系中大量金属氧化物破坏了CaO-Al2O3-SiO2三元系统的相间平衡,使维持系统平衡的共熔点降低,产生了多元氧化物的共熔融现象。(4)利用德国NETZSCH公司的DSC404 F3型高温差示量热扫描仪研究碱度变化对玻璃质熔渣析晶行为的影响,进而确定玻璃质熔渣热处理过程中的核化温度和晶化温度两个特征参数。结果表明碱度增加有助于基础玻璃的析晶温度降低,其原因在于原料由Fe2O3、K2O、Na2O、Ti2O、MgO等碱金属氧化物能促进基础玻璃析晶,引入的CaO添加剂作为网络改变体能有效地降低晶相转变过程中的能量投入(5)借助抗压强度、耐腐蚀性和重金属浸洗测试与X射线衍射、扫描电镜分析技术,研究碱度和热处理时间对微晶玻璃物化特性和微观结构特征的影响。研究表明：随着原料碱度的增加,微晶玻璃主晶相由钙硅石逐渐转变为钙长石,同时伴有方解石、多铝红柱石、透辉石和钙黄长石形成。适宜的碱度和热处理时间有助于微晶玻璃抗压强度、耐腐蚀性和重金属固化效果的提高。当碱度AK3=0.33时,微晶玻璃主晶相钙长石含量较高,且球状晶体颗粒成长饱满、大小均匀、排列紧密。(6)采用基于密度泛函理论的第一性原理计算方法,利用Materials Studio分子模拟软件中CASTEP模块,对硅酸盐晶体分子结构和掺杂重金属原子的晶体体系结合能进行模拟计算,探讨硅酸盐晶体固化重金属机理。结果表明：当借助外力使进入晶体空间内的金属原子脱离体系时,必须克服掺杂体系对原子产生的能垒。掺杂体系的结合能越大,使原子脱离体系的能垒越大,晶体对进入其体系内部的原子固化作用越强。更多还原

【Abstract】 With serious resource depletion caused by over-use of fossil fuel, it is urgent to seek the substitute energy. Among many substitute energies, oil shale resource has caused widespread attention due to huge reserves. Oil shale is a low-heating-value solid fuel with ash content in the range from 70wt% to 90wt%. According to the calculation of ash content, the ash yield will be in the range from 170.28 to 218.92 billion ton when the exploited oil shale is completely utilized and will be in the range between 287.87 and 647.95 billion ton when oil shale resource is completely utilized. With the exploitation and utilization of oil shale, the environmental pollution caused by waste slag with huge annual yield become more and more serious. There are some acid and alkali materials in oil shale waste slag, especially heavy metals. The potential hazard of pollutants can not be ignored due to contaminating surrounding soil, water area and atmosphere through surface runoff and floating dust. Therefore, it is necessary to realize the safe treatment of oil shale waste slag in order to maintain vigorous development of oil shale industry.In this paper, oil shale and oil shale fly ash (OSFA) were selected to discover the translocation regularity of heavy metals during circulating fluidized bed combustion through their fraction and content. Considering the enrichment of heavy metals in OSFA, some matters need attention will be put forward in the treatment of OSFA. By melting and sintering methods, nucleated glass-ceramics were produced from OSFA. The specific works are as follows:(1) The research on heavy metals with different fractions and content was carried out by Tessier sequential extraction in order to investigate the enrichment level of heavy metals in OSFA. The translocation regularity of heavy metals with different fractions during circulating fluidized bed combustion was studied through principal component analysis. Moreover, the toxicity assessment of heavy metals in OSFA was carried out by STI model.The resluts indicated that there were accumulations of heavy metals such as Cu, Cd, Pb, Zn in fly ash, and the enrichment mass of Pb and Zn added up to 117.02μg g-1 and 71.06μg g-1, respectively. The ecological risk of OSFA was notably intensified due to the high content of heavy metals with iron-manganese and exchangeable fractions.(2) The granularity distribution analysis of OSFA was carried out by mechanical grading. The feasibility and advantage of OSFA treatment by melting were expounded on the basis of the chemical compositons analysis of fly ash and the assessment of traditional ash treatment technique. Five glass materials prepared with CaO additive converted to molten-slag like glassiness by melting treatment. Then, the glass ceramics was produced by nucleation and crystallization treatment. The effect of alkalinity and heat treatment time on the performance index of glass ceramics was investigated in order to provide scientific information for commercial run.(3) Physicochemical characteristics analysis indicated that OSFA with thin granularity mainly consisted of multi-basic oxides such as SiO2, Al2O3, CaO, which were good raw materials for CaO-Al2O3-SiO2 system glass ceramics. The co-melting phenomenon occurred during the melting process of raw materials because a lot of metal oxides destroyed the interphase balance of CaO-Al2O3-SiO2 system and reduced the co-melting temperature which maintained the system balance.(4) The effect of alkalinity on the crystallization behavior of molten-slag like glassiness was investigated by differential scanning calorimeter named DSC404 F3 produced by German NETZSCH Company in order to determine the nucleation temperture and crystallization temperature. The results indicated that the increase of alkalinity conduced to bring down the nucleation temperture and crystallization temperature. Metal oxides such as Fe2O3, K2O, Na2O, Ti2O, MgO can accelerate the crystallization of molten-slag. CaO was considered as network modifier to be effective at reduction of energy input in crystallization transition.(5) The effects of alkalinity (AK) and heat treatment time on the physicochemical characterics and microstructure of glass ceramics were investigated by virtue of compressive strength, corrosion resistance, immersion cleaning of heavy metals, XRD and SEM analysis. The results indicated that the increase of alkalinity led to the transition of main crystallization phase in nucleated glass-ceramics from wollastonite to anorthite. Additionally, there were also calcite, mullite, diopside and gehlenite in glass ceramics. When AK3=0.33, the content of anorthite was high in glass ceramics, in which there were a lot of close sphere-shaped crystals with satiation and same size.(6) By first principles calculation on the basis of density functional theory, the CASTEP module of Materials Studio molecule simulation software was used to optimize the structure of silicate crystals and calculate the binding energy of crystal system adulterating heavy metal atoms in order to analyse the solidification mechanism of heavy metals in silicate crystals. The results indicated that energy barrier should be destroyed in order to make heavy metals escape from body system by virtue of external force. The body system had better effect on solidification of heavy metals entering into inner space of crystals when the energy barrier was stronger due to higher binding energy.更多还原