【作者】 周宛谕；

【导师】 施正伦； 骆仲泱；

【作者基本信息】 浙江大学 ， 工程热物理， 2010， 硕士

【摘要】 煤炭资源作为中国能源消费结构的主体,分布集中,北多南少,且灰分偏高,这就导致大量灰渣的排放。我国原煤资源相对贫乏的南方地区,却具有较为丰富的低碳低热值的石煤资源。但无论采用哪种工艺,石煤提钒后都会产生巨量的残渣,大部分将堆放灰渣场,既占用土地,又污染环境。一方面,在水泥生产中,硅铝质材料通常用粘土,但粘土反应活化能较高,导致水泥生产能耗很高,而且开采破坏植被,毁坏田地,导致许多发达国家已禁止使用粘土烧水泥。另一方面,水泥生产可以消耗大量的灰渣,因此,灰渣用于水泥生产既可以节约资源,又能改善环境条件,这是符合可持续发展战略思想的。为避免传统石煤提钒工艺存在的钒回收率低、污染环境、规模小等问题,本文采用循环流化床钙法焙烧工艺,以钙基原料为添加剂的敦煌石煤料球为焙烧原料,在热输入功率为1MW循环流化床燃烧试验台上进行含钒石煤料球循环流化床焙烧提钒试验研究,对燃烧后灰渣特性和灰渣钒浸出特性进行分析。试验结果表明,循环流化床对石煤中的钒矿物具有良好的焙烧氧化作用：焙烧产物以飞灰为主,占70%左右且V2O5的含量为1.38%,比石煤原样提高了23.2%；在液固比2,硫酸浓度15%,浸出温度90℃条件下,灰渣的V205浸出率接近70%。可以预见,敦煌石煤料球在实际循环流化床锅炉中焙烧,氧化效果将会更好,能使灰渣的钒浸出率进一步提高。对提钒残渣和气化灰渣进行物化特性分析。分析表明,提钒残渣和气化灰渣的化学成分以及矿物组成都与水泥生产中的粘土质原料极为相近,而且含有大量的富氧矿物和微量元素,活性很好,用来作生料配料可以促进熟料的烧成；用来作水泥混合材,也有利于水泥的水化作用,对抗压抗折强度的提高大有裨益。此外,气化飞灰含碳量29.53%,发热量可以达到8967kJ/kg,可以作为劣质煤来提供热量,应用立窑水泥的配料,达到节约能耗的目的。参考新型干法回转窑水泥煅烧工艺,对中间盐法酸浸提钒残渣进行生料配方设计,按照递减试凑法配制了15个生料配方,然后分别在1250℃、1300℃、1350℃、1400℃和1450℃五个温度下进行煅烧。通过对熟料进行游离氧化钙、XRD、SEM扫描电镜的分析和静浆抗压强度试验分析,并与厂熟料进行对比,可以看到提钒残渣和含钒石煤灰渣作水泥生料,熟料烧成温度降低50℃,减少煅烧时间,降低水泥煅烧能耗,提高生料的易烧性,提高熟料质量,所以使用提钒残渣和含钒石煤灰渣配制水泥生料煅烧熟料完全可行,而且很有意义。参考立窑水泥煅烧工艺,对灰熔聚气化炉飞灰作水泥生料进行配方设计。设定熟料率值KH=0.93～0.95,SM=1.8～2.2,IM=1.1～1.5,根据飞灰与无烟煤的不同配比,以飞灰代粘土的不同替代率,按照解方程法配制了91个生料配方,这表明气化飞灰可在一定生料率值范围内配制立窑水泥熟料煅烧工艺生料,且可较大幅度减少外配无烟煤,达到节能效果。对中间盐法酸浸提钒残渣作混合材进行了试验研究。分别按10%、15%、25%、30%、35%、40%和45%的质量比,将提钒残渣和厂石煤渣分别进行单掺和对掺,对不同配料的水泥试验样品进行物理检验,结果表明：提钒残渣是活性很好的水泥混合材材料,不论单掺还是和水泥厂石煤渣对掺,水泥安定性、凝结时间等性能指标均符合复合硅酸盐水泥要求,其强度均满足32.5等级水泥强度要求,水泥性能指标全部满足GB175-2007之规定。而且提钒残渣28d抗压抗折强度均高出水泥厂石煤渣很多,使其有可能成为一种特殊的水泥混合材产品出售,这将大大提高其身价,从而大幅度提高石煤多联产综合利用的经济效益和环境效益。对二次焙烧残渣作混合材进行了试验研究。分别按10%、20%、30%和40%的质量比,将提钒残渣2和厂石煤渣分别进行单掺和对掺,对不同配料的水泥试验样品进行物理检验,发现其水泥强度均满足32.5R强度等级水泥要求,水泥性能指标全部满足GB175-2007之规定。R28的测定表明它是活性很好的水泥混合材材料。当残渣掺入量达到40%时,残渣中的石膏成分足以代替外加石膏,不仅使残渣得到完全利用,还将降低水泥的石膏成本。最后,对灰熔聚气化炉排渣经循环流化床锅炉燃烧后的底渣作混合材进行了试验研究。分别按10%、15%、25%、30%、35%、40%和45%的质量比,将底渣和厂石煤渣2分别进行单掺和对掺,对不同配料的水泥试验样品进行物理检验,发现其抗折、抗压强度都至少满足32.5R等级水泥强度要求,绝大多数都达到42.5R等级水泥强度要求。R28的测定表明底渣是活性很好的水泥混合材材料。更多还原

【Abstract】 Coal, as the most important energy source in China, distributes in majority of north China with high ash content, which leads to large amounts of ash emission. However, Stone Coal, with low carbon content and low heat value, is comparatively abundant in south China. Vanadium, as an associated element of Stone Coal, is one kind of important strategic materials. Unfortunately, super-accumulation of leavings after extracting Vanadium will be overground stockpiled, which results in land occupation and environmental pullution. On the one hand, the current silicon aluminum material commonly uses clay in cement production. But due to its higher reaction activation energy, it needs excessive energy consumption during the process of calcinations, furthermore, clay mining destroys vegetation and farmland, therefore clay has been banned by many developed countries for cement production. On the other hand, cement production could consume large amounts of ash and leavings. Thus, ash used in cement production could not only saving rescources, but also improving environmental conditions, which is in accordance with the ideology of sustainable development strategy.To avoid the existing problems, such as low recovery rate of Vanadium, environmental pollution and small capacity in the conventional vanadium extraction processes, the calcium-modified roasting process in circulating fluidized bed was used. Mixed Dunhuang-Stone Coal with calcium-based additives as material ball, then put it in the circulating fluidized bed (thermal input power is 1MW) in order to study the Vanadium extraction characteristics of vanadium-containing stone coal calcination in CFB, ash characteristic and leaching characteristics of vanadium. The results showed that CFB had good effect on the roasting oxidation of Vanadium in stone coal because the main components of combustion products was fly ash with 70% Vanadium, which is 23.3% more than original Stone Coal and the V2O5 leaching rate of ash was close to 70% at a liquid-solid ratio of 2:1, sulfuric acid concentration of 15% and leaching temperature of 90℃. It is foresaw that the roasting oxidation and V2O5 leaching effect of Dunhuang Stone Coad could be better in the actual calcination of CFB.Physicochemical properties of Vanadium extraction leavings and gasified ash have been analyzed. It showed that the chemical constituents and mineral composition of these ash are very similar with the common argillaceous materials used in cement production, also contain lots of oxygen-rich minerals and trace elements which play a positive mineralization role in clinker calcination and cement hydration as well as the improvement of anti-pressure and anti-folded intensity. Besides, gasified fly ash contains 29.53% of carbon content and 8967kJ/kg of calorific value so that it can be uses as inferior coal for heat supply and ingredient for shaft kiln cement to save energy comsumption in cement industry.Based on the calcination process of Pre-calcining Kiln, we designed raw mix formula with Vanadium extraction leavings from the process of vanadium extraction by interim product with sulfuric acid leaching from ash of stone coal. We adopted Degression Making-up Method to optimize 15 formulations. Then we calcined it to be clinker under the calcination temperature of 1250℃、1300℃、1350℃、1400℃和1450℃. According to the analysis of fCaO, XRD, SEM and compression strength tests, comparing with the industry clinker, we can find that cement clinker is successfully calcined basically with the temperature of 50℃decreased. Therefore, we are sure that cement clinker with Vanadium extraction leavings as argillaceous material is successful and meaningful for the reason that it can reduce calcination time, save energy comsumption, increase burnability of raw meal and improve quality of clinker.Based on the erect kiln cement process, we designed raw mix formulations with fly ash.of ash-agglomerated gasifier. We set the three modulus KH=0.92-0.95, SM=1.8-2.2, IM=1.1-1.5. According to the different fly ash- anthracite ratio and fly ash replacement rate of clay, we adopted Equation-solving Method to optimize 91 formulations. It shows that gasified fly ash could be used as argillaceous material for erect kiln cement production and save energy for the remarkable reduction of Anthracite consumption.We have experimental study on the utilization of Vanadium extraction leavings from Acid Leaching Process as Cement Active Admixture. Vanadium extraction leavings used alone or mixed with stone coal ash in the weight ratio of 10%,15%, 25%,30%,35%,40% and 45%. According to the physical inspection of cement samples, we can find that Vanadium extraction leaving belongs to active admixture and whether it was used alone or mixed with stone coal ash, cement performances index met Ordinary Portland Cement Standard GB175-2007 and cement of 32.5 grade would be generated. Moreover, the 28d pressure intensity of Vanadium extraction leavings is far more than stone coal ash of cement factory, which makes Vanadium extraction leavings, used as cement active admixture, be sold at high price in order to greatly improve economic and environmental benefits of comprehensive utilization of Stone Coal.We have experimental study on the utilization of Vanadium extraction leavings from Second-calcination as Cement Active Admixture. The second Vanadium extraction leavings used alone or mixed with stone coal ash in the weight ratio of 10%, 20%,30% and 40%. According to the physical inspection of cement samples, we can find that whether the second Vanadium extraction leaving was used alone or mixed with stone coal ash, cement performances index met Ordinary Portland Cement Standard GB 175-2007 and cement of 32.5R grade would be generatedm, but the effect is still not as good as Vanadium extraction leavings from Acid Leaching Process. The results of R28 show that the second Vanadium extraction leaving belongs to active admixture. Gypsum, compositon of the second Vanadium extraction leavings, is enough to replace applied plaster.Therefore, the utilization of Vanadium extraction leavings from Second-calcination as Cement Active Admixture could not only use leavings entirely, but also reduce cost of gypsum in cement production.At last, we have experimental study on the utilization of bottom slag, which is the slag from CFB calcination of ash-agglomerated gasified slag, as Cement Active Admixture. The slag used alone or mixed with stone coal ash in the weight ratio of 10%,15%,25%,30%,35%,40% and 45%. According to the physical inspection of cement samples, we can find that whether the slag was used alone or mixed with the second stone coal ash, cement performances index met Ordinary Portland Cement Standard GB175-2007 and cement of 32.5R grade would be generatedm even up to 42.5R. Furthermore, the results of R28 also show that gasified bottom slag is more active than Vanadium extraction leavings from Acid Leaching Process. The results of R28 show that the second Vanadium extraction leaving belongs to active admixture.更多还原