Effect of Al Powder and Si Powder Additions on Structure and Properties of Unburned Magnesium Aluminate Spinel Refractories

Unburned magnesium aluminate spinel refractories were prepared using sintered magnesium aluminate spinel as the main raw material,phenolic resin as the binder,aluminum powder(2%,4%,and 6%by mass)and silicon powder(when Al powder addition is 4%,Si powder addition varies:1%and 2%,by mass)as additives.The effects of the Al powder and Si powder additions on the properties and microstructure of the refractories heat treated at different temperatures(1000,1400,and 1600℃for 3 h)were studied.The results show that the Al powder addition can greatly enhance the cold modulus of rupture of the samples fired at 1000 or 1400℃,and meanwhile AlN reinforcement phase forms in the matrix,which greatly improves the hot modulus of rupture of the samples at 1400℃;however,the heat treatment at 1600℃has little influence on the strength;the addition of Al powder and Si powder results in the formation of low melting point phases,greatly reducing the hot modulus of rupture.However,the low melting point phases promote sintering,which enhances the density and the cold modulus of rupture,and decreases the volume change during heating.The samples added with Al and Si all have higher cold modulus of rupture than those added with Al powder only.

Combustion characteristics of unburned pulverized coal and its reaction kinetics with CO2

The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms between UPC and CO2 in an isothermal experiment in the temperature range 1000–1100°C were investigated. The combustion performance of unburned pulverized coal made from bituminous coal (BUPC) was better than that of unburned pulverized coal made from anthracite (AUPC). The combustion characteristic indexes (S) of BUPC and AUPC are 0.47 × 10^-6 and 0.34 × 10^-6 %2·min^-2·°C^-3, respectively, and the combustion reaction apparent activation energies are 91.94 and 102.63 kJ·mol^-1, respectively. The reaction mechanism of BUPC with CO2 is random nucleation and growth, and the apparent activation energy is 96.24 kJ·mol^-1. By contrast, the reaction mechanism of AUPC with CO2 follows the shrinkage spherical function model and the apparent activation energy is 133.55 kJ·mol^-1.

Modeling of the Unburned Carbon in Fly Ash

Numerical simulation of the content of unburned carbon in fly ash on the 300MW tangentially pulverized coal fired boiler is performed by the numerical simulation software COALFIRE, which is based on international advanced TASCFLOW software platform. Firstly, take the result of calculation of number value as the sample, and then set up the support vector machine model of unburned carbon content on the boiler. The relative error between the predicted output and measured value is 0.00186%, which proves the modeling is good for the unburned carbon in fly ash predict.

Adsorption of Naphthol Green B on unburned carbon：2-and3-parameter linear and non-linear equilibrium modelling

The study deals with adsorption of Naphthol Green B on two unburned carbons and the parent coal,from which the UCs have been created in a fluidised-bed power station.Particular attention has been paid to the adsorption equilibrium modelling:experimental data has been analysed using 2-parameter(Langmuir,Freundlich) and3-parameter(Redlich-Peterson) isotherms — both linear and non-linear regressions have been used for the estimation of the isotherm parameters.In the case of both UCs,the Langmuir isotherm model provides the worst fit,whereas 2-parameter Freundlich and 3-parameter Redlich-Peterson models are both good,from which 3-parameter Redlich-Peterson isotherm provides slightly better results(despite the penalty used for the higher number of parameters).In the case of both UCs,the linear regression of Freundlich and Redlich-Peterson models provides good results(comparable with non-linear regressions).Unlike both UCs,the best fit of the experimental data from the adsorption on the coal has been achieved by the Langmuir isotherm model.The results based on the Freundlich or Redlich-Peterson model were(in this case) somewhat worse.

未燃煤粉对高炉炉渣流动性的影响

高炉喷吹煤粉技术是降低炼铁生产成本、优化高炉操作的主要技术手段,在高喷煤比条件下未能在风口回旋区燃尽的残炭颗粒以未燃煤粉形式进入料柱,过多的未燃煤粉会对炉渣性能产生不利影响。为了研究未燃煤粉对高炉炉渣流动性的影响,通过X射线衍射分析、扫描电子显微镜和能谱分析仪等分析手段研究了未燃煤粉在炉渣中的存在状态及对炉渣性能的影响。结果表明,未燃煤粉颗粒呈均匀状分布于炉渣中,添加未燃煤粉前后炉渣黏度与温度的关系均满足阿伦尼乌斯方程,并且黏度值随着温度降低均呈现出增大趋势。随着未燃煤粉固体颗粒质量分数增加,炉渣黏度呈线性增大趋势,并且炉渣中未燃煤粉含量越多,转速对非均相熔体黏度的影响越明显。

飞灰基吸附剂脱除烟气中Hg^(0)的研究进展

与其他脱汞方法相比,利用飞灰脱除Hg^(0)能降低脱除成本、实现以废治废。目前飞灰脱汞技术在工业应用中存在脱汞效率较低的问题,所以通过深入研究来提高其应用水平具有实际意义。归纳了飞灰结构和成分(有机、无机)对Hg^(0)脱除的影响机制。从提高脱汞效率角度,梳理了4种主流的飞灰改性方法:1)卤化物浸渍改性。卤化物在飞灰表面生成Br^(*)或与飞灰中未燃烧碳反应生成C-Br以氧化Hg^(0)。改性剂中的金属阳离子以加速电荷转移、降低反应能垒的方式来促进Hg^(0)的脱除。2)机械化学改性。该方法的制备工艺简单、成本低。飞灰经机械研磨使粒径减小后,无定形相及吸附氧含量增加。研磨后未燃烧碳充分暴露,卤化点位增加,加速了C-Br氧化Hg^(0)的进程。3)过渡金属改性磁珠。经过渡金属改性磁珠的磁性增强,可循环利用,使吸附剂表面引入新的Hg^(0)氧化位点(如C-O基团、Cl^(*))。4)低温等离子体改性。飞灰经低温等离子体处理后,吸附剂表面活性等离子体(如O、Cl等离子体)含量及官能团(C=O基团和酯基)含量增加,促进了Hg^(0)的吸附。进一步探究了复杂烟气组分对飞灰基吸附剂脱汞效率的影响,并对改性飞灰的脱汞性能及适用条件进行了评价。基于当前的研究进展,建议用磁性金属硫化物对飞灰进行机械化学改性来制备脱汞剂。

粉煤灰免烧陶粒制备技术研究进展

粉煤灰是煤电行业的主要固体废物,由粉煤灰制备陶粒是粉煤灰资源化利用的重要途径之一。本文概述了粉煤灰制备免烧陶粒的过程,并对粉煤灰免烧陶粒的制备技术进行了综述,详细探讨了影响粉煤灰免烧陶粒产率和性能的因素,对未来粉煤灰免烧陶粒制备技术的发展方向进行了展望,为粉煤灰免烧陶粒的研究提供参考和建议。

生态烧结料制备免烧砖试验研究

以生态烧结料为主要原料,采用压制成型法制备免烧砖,研究了成型压力、原料配比等对免烧砖抗压强度的影响,并进行了免烧砖制备工业化试验。结果表明:成型压力20 MPa时,在m(生态烧结料):m(水泥):m(炉渣):m(废砖石)=45:15:15:25条件下,免烧砖的7、28 d抗压强度分别达到12.98、16.04 MPa;按照优化的原料配比,工业化试验制备的免烧砖性能符合JC/T 422—2007《非烧结垃圾尾矿砖》中MU15要求,试样表面无凹凸、裂缝、破损和分层等现象。凝胶物质与生态烧结料中矿物以及其他物质相互交织,将胶凝材料体系中的颗粒紧密包裹,形成致密的网状结构,提高了免烧砖的抗压强度。

Effect of unburned carbon content in fly ash on the retention of 12 elements out of coal-combustion flue gas

The aim of this study was to evaluate whether unburned carbon particles present in fly ash can help in the retention of S, Cl, Br, As, Se, Cu, Ni, Zn, Ga, Ge, Rb, and Pb out of flue gas during the coal combustion at fluidised-bed power station where the coal was combusted along with limestone. The competitive influence of 10%-25% CaO in fly ashes on the distribution of studied elements was studied as well to be clear which factor governs behaviour of studied elements. Except of S （with significant association with CaO） and Rb and Pb （with major affinity to A1203） the statistically significant and positive correlation coefficients were calculated for the relations between unburned carbon content and Br （0.959）, Cl （0.957）, Cu （0.916）, Se （0.898）, Ni （0.866）, As （0.861）, Zn （0.742）, Ge （0.717）, and Ga （0.588） content. The results suggest that the unburned carbon is promising material in terms of flue gas cleaning even if contained in highly calcareous fly ashes.

Unburned Carbon Loss in Fly Ash of CFB Boilers Burning Hard Coal

The unburned carbon loss in fly ash of circulating fluidized bed (CFB) boilers, most of which are burning active fuels such as lignite or peat, is normally very low. However, most CFB boilers in China usually burn hard coals such as anthracite and bituminous coal and coal wastes, so the carbon content in the fly ash from these boilers is higher than expected. This paper investigates the source of unburned carbon in the fly ash of CFB boilers burning hard coal through a series of field tests and laboratory investigations. The char behavior during combustion, including fragmentation and deactivation, which is related to the parent coal, has an important impact on the carbon burnout in CFB boilers. The research shows that char deactivation occurs during char burnout in fluidized bed combustion, especially for large particles of low rank coal. The uneven mixing of solids and air in the core region of the furnace also causes poor burnout of carbon in CFB fly ash. An index describing the volatile content (as dry ash free basis) over the heating value is proposed to present the coal rank. The coal combustion efficiency is shown to be strongly connected with this coal index. Several changes in the CFB boiler design are suggested to reduce the unburned carbon loss in the fly ash.

Recent progress on laser-induced breakdown spectroscopy for the monitoring of coal quality and unburned carbon in fly ash

Our recent progress on developments of laser-induced breakdown spectroscopy （L[BS） based equipments for on-line monitoring of pulverized coal and unburned carbon （UC） level of fly ash are reviewed. A fully software-controlled LIBS equipment comprising a self-cleaning device for on-line coal quality monitoring in power plants is developed. The system features an automated sampling device, which is capable of elemental （C, Ca, Mg, Ti, Si, H, Al, Fe, S, and organic oxygen） and proximate analysis （Qad and Aad） through optimal data processing methods. An automated prototype LIBS apparatus has been developed for possible application to power plants for on-line analysis of UC level in fly ash. New data processing methods are proposed to correct spectral interference and matrix effects, with the accuracy for UC level analysis estimated to be 0.26%.

Behavior of liquid passing through deadman:influence of slag/iron ratio and unburned pulverized coal

The ability of a blast furnace hearth liquid(iron and slag)passing through deadman characterizes the activity of the blast furnace hearth.To explore the influence of various factors on the static holdup rate of liquid in the process of passing through the deadman,a physical transport model of liquid passing through the deadman was firstly established.Then,a self-designed experimental device was used to simulate the process,and the influences of slag/iron ratios(250–450 kg/t)and unburned coal content(0%–9%)on the static holdup rate were studied.The experimental results indicate that with the slag/iron ratio increasing,the behavior of liquid passing through the coke packed bed gets much more difficult,and the static holdup rate increases.As the content of unburned pulverized coal(UPC)increases,the static holdup rate decreases first and then rises.This is caused by the dual effects of UPC.On the one hand,UPC can promote the carburizing reaction of unsaturated molten iron,thereby improving the fluidity of molten iron and reducing the static holdup rate.On the other hand,when the content of UPC rises to a certain level,it will be regarded as a kind of solid particle which will increase the liquid viscosity,causing an increase in the static holdup rate.Moreover,the liquid and coke will present interfacial chemical reactions when the liquid flows through the coke packed bed.And the Si-containing iron droplets at the slag–coke interface,generated by the reaction of SiO_(2)with C in the coke,can improve the interface wettability by reducing the interface wetting angle and increase the basicity of slag by consuming SiO_(2),thus improving the fluidity of the liquid and reducing the static holdup rate.

钒尾矿制备免烧砖工艺及机理分析

陕南地区酸浸提钒尾矿堆存量大,存在极大的安全隐患和环境隐患。为了促进尾矿的利用,减小其堆存给矿山和社会带来的危害,以钒尾矿和水泥为主要原料制备免烧砖,进行了尾矿的基本性质和环境安全性分析,对制备免烧砖工艺过程中的物料配比、外加剂种类及用量、用水量和成型压力进行了系统研究,并通过X射线衍射和扫描电镜分析了免烧砖强度形成的机理。研究结果表明:钒尾矿中石英和石膏含量高,且毒性浸出及放射性均满足建材标准要求,能够用于制备免烧砖;在钒尾矿和水泥质量配比为85∶15、三乙醇胺掺入量为7.5‰、用水量为15%、成型压力为12.5 MPa的条件下,可以制备出MU15等级的免烧砖;免烧砖养护过程中,钒尾矿和水泥中的矿物发生水化作用,形成水化硅酸钙、水化铝酸钙等,矿物质交联成致密的结构,保障了免烧砖的强度。使用钒尾矿制备免烧砖对尾矿的利用率高,是实现尾矿减量化、大宗化利用的一种有效方案。

Numerical Study on Reduction of NO_x and Unburned Carbon in Micronized Coal Reburning

在一个照原尺寸的无关地发射的锅炉的烟煤美国南北战争时南军士兵 urning 的三维的数字模拟与 CFD 方法被进行学习美国南北战争时南军士兵瓮地区长度的效果，美国南北战争时南军士兵瓮嘴的高度，在美国南北战争时南军士兵的 stoichiometric 比率瓮地区，在苍蝇灰的 NOx 减小效率和未燃的碳上的美国南北战争时南军士兵瓮燃料部分和美国南北战争时南军士兵瓮煤上好。当美国南北战争时南军士兵瓮嘴的相对高度是大约 0.21， stoichiometric 比率在美国南北战争时南军士兵瓮地区在 0.8 和 0.9 之间时，结果显示 NOx 减小效率到达最大的价值；NOx 减小效率与美国南北战争时南军士兵瓮地区长度，美国南北战争时南军士兵瓮燃料部分和美国南北战争时南军士兵瓮煤粒子尺寸的减少增加；煤粒子尺寸越小，煤的染料烧尽表演是越多更好。

硫型免烧自养反硝化填料制备及其脱氮性能研究

针对目前自养反硝化填料成本高、结构不稳定等缺点,利用硫铁矿和硫磺为主要原料通过免烧法得到硫型免烧填料(SUF)。结果表明,SUF破碎率低(4.73%)、孔隙丰富,SUF反应器启动时间短(12 d),在提高进水NO3--N浓度阶段,进水NO3--N质量浓度在15~30 mg/L范围内,SUF反应器对NO3--N的平均去除率为88.14%,在进水NO3--N质量浓度提升至44 mg/L时,SUF反应器能够适应并迅速恢复高效运行,平均去除率为90.84%,显示出了优异的脱氮性能。相比于市售填料(CF),SUF在保证脱氮效率的同时,成本更低且结构稳定。SUF反应器中主要功能菌属为Ferritrophicum、Sulfurimonas、Thiobacillus等,SUF中的硫和硫化物作为电子供体被微生物利用。

利用余泥渣土制备高强免烧砖的试验研究

城市化建设产生的大量余泥渣土已造成了明显的生态环保问题,余泥渣土的资源化利用显得尤为迫切。以余泥渣土为主要材料,通过加入水泥、石灰、砂等分别研究了含水率、石灰、砂对免烧砖强度的影响,且制备了一种高强度免烧砖。随着渣土含水率的增大,免烧砖的抗压强度先增大后降低。随着石灰掺量的增大,免烧砖的抗压强度随着降低。当加入砂时,免烧砖的强度大幅增大,28 d抗压强度达到40.2 MPa。

泥岩地层盾构渣土免烧砖制备技术研究

针对成都地区泥岩地层盾构渣土,利用水泥为固化剂、粉煤灰为活性增强材料、细砂为级配材料,通过压制成型制备泥岩渣土免烧砖,在混凝土标养室养护14 d,研究不同配合比对免烧砖抗压强度的影响。结果表明:免烧砖的抗压强度与水泥掺量呈线性正相关,细砂掺量对免烧砖抗压强度的影响较小;粉煤灰无法与水泥进行等量替换实现抗压强度的提高。当配合比为渣土58%、水泥22%、细砂15%、粉煤灰5%时,免烧砖的抗压强度和软化系数符合JC/T 422-2007《非烧结垃圾尾矿砖》中MU15等级要求,且表面无凹凸、破损、裂缝、分层现象。

螺旋溜槽摇床联选对气化渣提碳行为研究

气化渣作为煤化工行业主要固体排放物,其处理方式直接决定着煤化工行业的可持续性发展前景。如何高效分选气化渣中未燃碳与硅酸盐相组分是气化渣综合利用研究的重点。本文采用螺旋溜槽和摇床联选工艺对气化渣进行了提碳行为研究,使用汉考克效率、固定碳回收率对分选效果进行评价,借助XRD、SEM等手段分析富碳产品性质。研究结果表明,螺旋溜槽初选效果显著,精矿固定碳含量由23.1%升至67.5%,尾矿固定碳含量降至1.6%。螺旋溜槽中矿、尾矿二段选别效果较好,气化渣中未燃碳与硅酸盐相得到进一步分离;螺旋溜槽精矿二段选别效果较差。最终联选生产可得富碳产品和富灰产品,其中,富碳产品产率为29.2%,固定碳含量大于60%,热值为5000 kcal;富灰产品烧失量小于5%,达一级粉煤灰标准。XRD结果表明,富碳产品中无机相主要成分为石英和方解石;SEM结果表明,多孔未燃碳基体中存在少量可分离硅酸盐相,存在二次提质的可能性。气化渣联选工艺在实现未燃碳提质的同时,也为后续制备气化渣基高品质建材提供了基础条件。

基于巢湖疏浚底泥的免烧砖制备及其最佳工艺参数研究

基于巢湖疏浚底泥,研究了固化材料种类与掺量、成型压力及加载速率、养护方式对底泥固结体抗压强度的影响,基于最优配合比和工艺参数制备了疏浚底泥免烧砖。结果表明,疏浚底泥固化材料的最佳配合比为:疏浚底泥62.0%、水泥12.5%、生石灰2.5%、粉煤灰2.5%、矿粉7.5%、水12.2%、水玻璃0.8%;最佳成型工艺参数为:成型压力15 MPa,加载速率0.4 mm/s,采用70℃蒸汽养护,制备的疏浚底泥免烧砖吸水率为13.2%,7 d平均抗压强度为18.5 MPa,单块砖最低抗压强度为16.3 MPa,冻融后平均抗压强度为17.1 MPa,单块砖的干质量损失率≤1.6%,符合MU15抗压强度、吸水率和抗冻性的要求。

免烧类绿沸石基复合材料的合成及其净水性能

为解决矿物凝聚除藻技术不能同步除氮除磷、材料易散失、底泥量大、去除效果持续性短等弊端,对11种矿物材料进行吸附去除NH_(4)^(+)-N、TP、Chl-a和TUB的性能测定筛选,以吸附NH_(4)^(+)-N效果最好的绿沸石为基础材料,制备5种免烧类绿沸石基复合材料(NGZC),分析NGZC的表面形貌结构,探讨了发泡剂和水泥用量、绿沸石与其余矿物的物料比等因素对NGZC净水性能的影响,以及NGZC投加量、水处理反应温度和时间等因素对去除河道污水中多种污染物效果的影响。结果表明,在设定的养护条件下,NGZC最佳制备条件为:水泥掺量为10%~15%,发泡剂掺量为0.25%~0.5%,绿沸石与牡蛎壳、凹凸棒石黏土、活性白土、水滑石、赤玉土的物料比分别为8∶2、4∶6、6∶4、4∶6、4∶6。最佳水处理条件为:25℃下,200 mL污染河水中加4 g NGZC,处理3 d。本研究为藻型富营养化水体的污染修复、非金属矿物和废弃物的资源化利用和水土保持等提供低成本的复合净水材料和新技术。