石灰在石煤钙化焙烧中固硫作用的研究

本研究对石煤清洁焙烧工艺（钙化焙烧）进行了研究，发现钙化焙烧除可完全避免钠化熔烧过程中Cl2，HCl等有害气体的产生外，石灰在焙烧过程中有很好的固硫效果。实验结果表明，当焙烧温度不高于1000℃，石灰加入量为理论量的1.4倍以上时，保证适当的焙烧时间与空气量，石灰的固硫率可达99%。     

掺固硫灰AC-13型沥青混合料配合比设计

固硫灰是循环流化床锅炉燃煤固硫产生的废弃物,具有自硬性、火山灰活性和膨胀性等特性,若以其替代矿粉制备沥青混合料并用于道路工程建设中,将有望为固硫灰处理处置提供新途径。选用固硫灰做填料等量替代普通矿粉,通过马歇尔实验研究固硫灰不同替代量(0%、25%、50%、75%、100%)对AC-13型沥青混合料性能的影响,并对机理进行了分析。结果表明,掺固硫灰沥青混合料在一定油石比范围内均能满足现行规范要求,与普通矿粉沥青混合料相比,掺固硫灰沥青混合料水稳定性良好,压实度相同时,掺固硫灰沥青混合料具有更好的抗车辙性。     

型煤燃烧过程中石灰石固硫的试验研究（Ⅱ）

采用石灰石作固硫剂，考察其加入量和空气流量对北宿型煤固硫的影响，研究了固硫型煤矿析出特性和石灰石对不同煤的固硫能力。研究表明：石灰石的最佳固硫温度为８００℃、Ｃａ／Ｓ＝２：１；石灰石中所含的杂质对低温固硫有利，煤中所含钙基组分对固硫有利，石灰石对低灰熔点煤高温固硫不利。     

磁化焙烧-磁选法回收循环流化床固硫灰中铁

西南地区原煤中硫铁矿含量相对较高,其燃煤灰渣一般呈暗红色,有一定量赤铁矿存在,有必要回收这部分铁资源。采用磁化焙烧—磁选工艺对循环流化床燃煤固硫灰中的铁资源进行了回收。研究结果表明,焙烧温度800℃,焙烧时间90 min,还原剂用量5%,粗选磁场强度为200 kA/m,精选磁场强度为80 kA/m条件,能够获得品位58.02%的铁精矿,回收率为76.27%。     

可燃固废复合燃料的固硫固氯效果

以可燃垃圾、污水污泥和煤粉为原料,添加园林残余、固硫剂等按L16(45)正交表配料,采用机械成型设备制备固废复合燃料,研究燃料组分对固硫固氯效果的影响。固硫率、固氯率实验数据的极差、方差分析结果显示:CaO添加量对固硫率、固氯率的影响最显著;MnO2添加量对固氯率的影响仅次于CaO添加量,但对固硫率没有影响。运用ForStat 2.0统计软件建立了固硫率、固氯率指标的预测方程,置信度大于95%。应用综合评分法筛选出最佳固硫固氯效果的燃料制备配方为:A2B3C2D3,即垃圾、污泥、煤粉以2∶1∶1比例混合,园林残余为10%,助燃剂MnO2添加量为0.17%,固硫剂CaO添加1.2%时所制备的燃料,燃烧中固硫率可达74.55%,固氯率可达77.35%。     

循环流化床燃煤固硫灰改良云南红粘土

为因地制宜寻求适合固硫灰大掺量利用的新途径,解决固硫灰滞销的问题,提高固硫灰的综合利用率,利用固硫灰具有游离氧化钙含量高、火山灰特性、自硬性的特点,将其掺入红粘土进行土质改良,开展土工实验,以满足高速路基填筑材料技术要求为指标,确定适宜的固硫灰掺入量。结果表明:在红粘土中掺入适量固硫灰,能够有效降低塑性指数、增强压实性、提高承载比,固硫灰掺入量为30%以内,CBR可提高至5%以上,符合路床土最小强度要求;当固硫灰掺入量为10%~20%时,CBR可提高至15%以上,符合高速公路路床土最小强度要求。在红粘土中掺入适量固硫灰,能够有效改良红粘土,当固硫灰掺入量为10%~20%时,改良红粘土用作高速公路路床土在技术上是可行的。     

MnO2对煤粉中CaO固硫效率影响机理

采用热力学计算和实验方法对钙硫比n（CaO）/n（S）=2.0条件下不同钙基固硫剂的固硫效果进行了比较,发现：CaO的固硫效率最高。以CaO为固硫剂,研究了添加剂MnO2对CaO固硫效果的影响。结果表明,加入MnO2可以提高CaO的固硫效率,且其含量为1%时对CaO固硫的促进效果最佳。这是因为煤粉燃烧过程中MnO2将逐级分解,分解产物依次为Mn2O3和Mn3O4,锰的氧化物一方面可以催化CaO的固硫反应,另一方面,Mn3O4本身也参与到固硫反应之中,生成MnSO4,从而促进钙基固硫剂的固硫效果。     

Mg/Al/Fe水滑石的焙烧产物对F~-的吸附

采用共沉淀法合成Mg-Al-Fe类水滑石,并通过不同焙烧温度制得焙烧类水滑石。采用XRD,FT-IR,SEM等方法进行了吸附材料表征。研究了焙烧温度,吸附剂投加量,吸附时间,吸附初始p H值,吸附动力学,吸附等温线、吸附热力学等因素对Mg-Al-Fe类水滑石及其焙烧产物吸附F-的效果。研究表明,500℃焙烧类水滑石吸附效果最好,0.2 g吸附剂是最佳投加量值,在p H变化范围为3~8内吸附量基本无变化。研究结果表明,焙烧水滑石吸附符合准二级动力学曲线,反应活化能为E_a=14.63 k J/mol。反应基本符合Langmuir吸附等温模型。△G~0为负值表明该反应是一自发进行过程。高温有利于吸附反应进行。     

复合固硫剂对型煤固硫的影响研究

固硫型煤作为煤燃烧中脱硫的一种重要方法，在燃煤SO2的减排方面起着重要的作用。为了考察固硫剂和固硫添加剂对型煤固硫及其对型煤燃烧释放SO2的规律的影响，对利用氧化镁和氧化钙为固硫剂，以煤矸石和粉煤灰为固硫添加剂进行了研究，同时通过XRD和SEM表征，进一步探讨了固硫剂及添加剂的固硫作用和机理。研究结果表明：(1)CaO...     

型煤燃烧过程中石灰石固硫的试验研究（Ⅰ）：CaCO3,Na2CO3和K2C …

以高有机硫北宿烟煤为研究对象,在对石灰石中各组分进行固硫试验的基础上,对固硫能力较强的ＣａＣＯ３,Ｎａ２ＣＯ３和Ｋ２ＣＯ３在不同温度,不同固硫剂用量条件下进行了固硫试验研究,并利用改进的自动测硫仪对ＣａＣＯ３,ＮａＣＯ３和Ｋ２ＣＯ３作固硫剂时固硫型煤的硫析出特性进行了研究。     

CaO/SiO2对流化床焚烧飞灰熔融过程中重金属挥发的影响

对掺煤混烧的流化床焚烧飞灰熔融过程中重金属在气相(吸收率)中和固相(固定率)中的分布进行了研究,并采用HNO3-NaOH2级吸收方式对气相重金属进行了吸收.结果表明,CaO/SiO2(摩尔比)对重金属的迁移行为有重要影响,CaO/SiO2降低,Cd、Pb固定率总体呈上升趋势;2级吸收对气相重金属的吸收有限,大部分重金属主要溶解在HNO3吸收液中,但NaOH吸收液对Cr的吸收效果好于HNO3吸收液;氯对重金属的挥发有重要影响,当重金属以氯化物形式存在时,其挥发受到SiO2的限制.随着SiO2含量增加,挥发率降低.     

基于CaO2的污泥处理应用技术研究进展

随着污水处理厂排泥量的剧增,污泥的处理处置成为当今急需解决的环境问题之一。基于目前污泥处理中CaO₂相关技术的研究现状,综述了CaO₂技术对于污泥减量化、无害化、资源化处理的促进作用,包括改善污泥脱水性能、实现污泥增溶减量、去除污泥中的有机污染物及重金属、促进污泥厌氧消化产酸产氢产甲烷等,展望了CaO₂相关技术的发展前景,以期为CaO₂相关污泥处理技术的研究与应用提供参考。     

润滑油废白土的热解处理

以润滑油废白土为原料,利用电热解法,研究了热解终温、加热速率和CaO添加量对热解产物的影响。实验结果表明:热解终温对热解产物的影响最为显著。随着热解终温的升高,不凝气产量和产油率均迅速增加。当热解终温达到600℃时,其增加的速率逐渐缓慢增大。当控制热解终温为800℃、加热速率为16℃/min、CaO添加量为0.5%时,富氢气体产量为189.2 L/kg,气体中主要成分为H2和CH4,其含量分别为27.97%和41.64%;热解残渣含油率和重金属溶出物均低于标准规定值,热解油产率为10.98%,回收率为38.94%,其主要成分为汽油、柴油和重油3部分组成,分别含19.13%、31.35%和49.52%。     

Comparison of CaO’s effect on the fate of heavy metals during thermal treatment of two typical types of MSWI fly ashes in China

Both grate and fluidized bed incinerators are widely used for MSW incineration in China. CaO addition for removing hazardous emissions from MSWI flue gas changes the characteristics of fly ash and affects the thermal behavior of heavy metals when the ash is reheated. In the present work, two types of MSWI fly ashes, sampled from both grate and fluidized bed incinerators respectively, were thermal treated at 1023–1323 K and the fate of heavy metals was observed. The results show that both of the fly ashes were rich in Ca and Ca-compounds were the main alkaline matter which strongly affected the leaching behavior of heavy metals. Ca was mostly in the forms of Ca(OH)₂ and CaCO₃ in the fly ash from grate incinerator in which nascent fly ash particles were covered by Ca-compounds. In contrast, the content of Ca was lower in the fly ash from fluidized bed incinerator and Ca was mostly in the form of CaSO₄. Chemical reactions among Ca-compounds caused particle agglomeration in thermal treated fly ash from grate incinerator, restraining the heavy metals volatilization. In thermal treated fly ash from fluidized bed incinerator, Ca was converted into aluminosilicates especially at 1323 K which enhanced heavy metals immobilization, decreasing their volatile fractions as well as leaching concentrations. Particle agglomeration hardly affected the leaching behavior of heavy metals. However, it suppressed the leachable-CaCrO₄ formation and lowered Cr leaching concentration.     

Woody biomass and RPF gasification using reforming catalyst and calcium oxide

This study focused on steam gasification and reforming of waste biomass using a reforming catalyst. The purpose of the study was to evaluate the durability of a commercial Ni reforming catalyst and the effect of CaO on the reforming behavior, and to clarify detailed factors of catalytic performance, as well as the effect of operating parameters on the characteristics of produced gas composition. Moreover, catalyst regeneration was carried out and the behavior of catalytic activity based on gas composition was investigated. Using a fluidized bed gasifier and a fixed bed reformer, gasification and reforming of waste biomass were carried out. Commercial Ni-based catalyst and calcined limestone (CaO) were applied to the reforming reaction. Temperature of the gasifier and reformer was almost 1023 K. Ratio of steam to carbon in the feedstock [mol mol⁻¹] and equivalence ratio (i.e., ratio of actual to theoretical amount of oxygen) [-] were set at about 2 and 0.3, respectively. The feed rate of the feedstock into the bench-scale gasifier was almost 15 kg h⁻¹. The results of waste biomass gasification confirmed the improvement in H₂ composition by the CO₂ absorption reaction using the reforming catalyst and CaO. In addition, CaO proved to be especially effective in decreasing the tar concentration in the case of woody biomass gasification. Catalytic activity was maintained by means of catalyst regeneration processing by hydrogen reduction after air oxidation when woody biomass was used as feedstock.     

Acute toxicity of cadmium to fish Labeo rohita and copepod Diaptomus forbesi pre-exposed to CaO and KMnO4

96-h LC₅₀ values of cadmium (Cd) to fish Labeo rohita and the copepod Diaptomus forbesi, determined by static bioassays, were, respectively, 89.5 and 10.2 mg/l. LC₅₀ values increased significantly when fish pre-exposed to 100–350 mg/l CaO or 0.5–1.5 mg/l KMnO₄ for 4 d and the copepod to 20–70 mg/l CaO or 0.25–1.0 mg/l KMnO₄ for same period. The LC₅₀ values also increased when the pre-exposure period of CaO was increased to 12 d at concentration 100 mg/l for fish and 20 mg/l for copepod. All fish died when pre-exposed to 1.5 mg/l KMnO₄ for 8 d. But LC₅₀ values of Cd to copepod increased when pre-exposure period of 0.5 mg/l KMnO₄ was increased from 4 to 8 d.     

Enhanced heavy metal immobilization in soil by grinding with addition of nanometallic Ca/CaO dispersion mixture

This study investigated the use of a nanometallic Ca and CaO dispersion mixture for the immobilization of heavy metals (As, Cd, Cr and Pb) in contaminated soil. Simple grinding achieved 85-90% heavy metal immobilization, but it can be enhanced further to 98-100% by addition of a nanometallic Ca/CaO dispersion mixture produced by grinding. Observations using SEM-EDS elemental maps and semi-quantitative analysis showed that the amounts of As, Cd, Cr, and Pb measurable on the soil particle surface decrease after nanometallic Ca/CaO treatment. The leachable heavy metal concentrations were reduced after nanometallic Ca/CaO treatment to concentrations lower than the Japan soil elution standard regulatory threshold: <0.01 mg L⁻¹ for As, Cd, and Pb; and 0.05 mg L⁻¹ for Cr. Effects of soil moisture and pH on heavy metal immobilization were not strongly influenced. The most probable mechanisms for the enhancement of heavy metal immobilization capacity with nanometallic Ca/CaO treatment might be due to adsorption and entrapment of heavy metals into newly formed aggregates, thereby prompting aggregation of soil particles and enclosure/binding with Ca/CaO-associated immobile salts. Results suggest that the nanometallic Ca/CaO mixture is suitable for use in immobilization of heavy-metal-contaminated soil under normal moisture conditions.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.