转炉钢渣磁选提铁研究

采用企业转炉钢渣进行了磨矿一磁选实验,探讨了钢渣磨矿粒度与时间的关系,在给定磨矿粒度下分别进行了弱磁和强磁磁选实验,探讨了磁选得到的精矿品位和铁回收率等问题.研究结果表明:转炉钢渣硬度大,难磨,弱磁磁选得到的铁精矿品位与原渣铁相比大幅度提高,转炉渣原渣磁选后的铁精矿品位为84.05％,可作为炼钢原料回收利用.强磁磁选得...     

炉排式垃圾焚烧炉的结渣特性研究

为了进一步掌握炉排式垃圾焚烧炉的结渣特性和形成机理,选取炉内典型渣块展开研究.通过XRD物相分析、扫描电镜和能谱分析研究炉内结渣特性,并通过化学热力学平衡反应计算与试验结果进行了比较.结果表明,CaO、Al2O3/MgO/ZnO、SiO2等反应生成的钙化合物形成的低熔点共熔物相的存在是灰渣形成的主要原因.渣块内 Si和Ca的分布趋势几乎是完全相同,Fe具有局部富集,Na和K对初始层的形成起主要作用.     

炉排_循环床垃圾焚烧炉过热器结渣现场实验

为研究焚烧炉过热器内的飞灰沉积、沾污和结渣的原因及影响因素,在260 t/d炉排-循环床垃圾焚烧炉过热器区域安放结渣实验采样段,利用SEM/EDX、XRF和XRD等方法分析了积灰和渣的成份和形态。研究表明:管束的几何结构对结渣有重要的影响,受热管越细越容易结渣。高温过热器渣层上的颗粒排列紧密,呈砖形,长度约2～5μm,物相组成为CaSO4、石英、SiO2、Ca2SiO4等。垃圾焚烧炉结渣主要是由粘结性颗粒撞击管壁所致。     

氯化焙烧法回收铜渣中铜的热力学研究

对铜渣氯化焙烧过程中各主要组分的反应热力学行为进行了理论分析.热力学分析结果表明,CaCl2为氯化剂对铜渣进行氯化焙烧时,其自身离解须在有氧环境中并在铜渣中SiO2组分的作用下才可发生,且反应体系中介入FeSO2,可较大程度促进CaCl2的离解.渣中含铜物相Cu2O、Cu2S及CuS在焙烧温度下可发生氯化反应,含铁物相Fe3O4和Fe2SiO4两者的氯化反应则不可发生,即过程可实现铜渣的选择性氯化.所形成氯化物挥发过程中,单一氯化物可发生聚合反应,且所形成聚合物的蒸汽压比单一氯化物相对较高.     

循环流化床燃烧生物质的结渣问题研究

在0.2 MW循环流化床上进行实验,以棉杆为燃料,分别采用石英砂和高铝矾土颗粒作为床料,长时间稳定运行.对运行过程中的床料、结渣块取样进行XRF以及SEM分析,分析生物质循环流化床运行中产生结渣的原因.研究结果表明,床料和结渣块中富集了大量的碱金属,并且随着运行时间的延长,富集的含量越来越高.生物质灰中的碱金属和床料中的SiO2反应生成低共熔点的硅酸盐化合物是引起结渣的主要原因.     

钢渣制备铸余渣处理用格栅试验研究及应用

利用钢渣为主要原料制备铸余渣处理用格栅材料,研究不同水泥、热闷钢渣、风碎钢渣添加量对格栅材料力学性能和耐火度的影响.结果 表明:水泥12％,热闷渣88％时制备的格栅材料7d和28d抗压强度分别达到15.77MPa、23.78MPa,耐火度为1370℃,综合性能最优.工业应用试验效果表明,采用钢渣制备铸余渣处理用格栅可实现铸余渣热态解体率达到50％,降低了切割处理导致的金属损失、粉尘排放和劳动强度.     

石灰石对流化床焚烧炉结焦结渣的抑制特性研究

研究有机浓缩废液焚烧过程中,石灰石添加剂对流化床焚烧炉结焦结渣的抑制作用.结果表明:加入石灰石添加剂,焚烧炉运行比较稳定、床层流化正常,渣样晶相组成主要为Na6Ca3Si6O18、(Na0.8-Ca0.1)2SiO4、Ca2SiO4等高熔点物相,渣样结构比较疏松;晶粒没有熔融衔接;说明加入石灰石能够很好地抑制焚烧炉的结焦结渣.     

碳捕捉对电石渣-钢渣复合相变储热材料性能的影响

为资源化利用工业固废,降低储热系统成本,选取电石渣和钢渣1∶1混合进行CO₂捕集和封存,将封存CO₂的电石渣-钢渣混合材料作为骨架材料制备7种不同配比的NaNO₃/固碳电石渣-钢渣复合相变储热材料。通过热重分析法探究电石渣-钢渣混合材料的固碳性能,利用差示扫描量热法、高温热冲击法、X射线衍射法、电子显微法表征其储热性能、热循环稳定性、化学相容性和微观结构。结果表明,电石渣-钢渣混合材料的固碳率为24.48%;最佳热性能样品CC-SC4中NaNO₃、电石渣和钢渣的质量比为2∶1∶1,100～400℃工作温度内储热密度达到444.2 J/g,热导率为1.057 W/(m·K),各组分间具有良好的化学相容性;样品CC-SC4经历1440次加热/冷却循环后仍具有优异的储热性能。     

生物质与煤掺烧对锅炉结渣特性影响的实验研究

采用CAF digital imaging灰熔点测试仪和飞利浦分析仪器分别对稻草、木屑、谷壳等常见的生物质灰及其与煤掺烧后灰的熔融特性和灰成分进行了检测,通过软化温度DT,灰分的酸碱比(B/A)、硅铝比(SiO2/Al2O3)、硅比(G)、铁钙比(Fe2O3/CaO)等判别指数对单一生物质与煤掺烧的结渣特性进行了研究和分析.结果表明:稻草和谷壳与煤粉掺烧,灰熔点降低,引起结渣.但是掺烧木屑则不会出现灰熔点降低而导致结渣的问题.     

Fe_2O_3/SiO_2/TiO_2复合薄膜的制备与表征

采用溶胶.凝胶法制备了Fe2O3/SiO2/TiO2三元复合薄膜.通过XRD表征、紫外.可见透射光谱分析,考察了Fe2 O3/SiO2对TiO2晶型、亲水性、光催化性能的影响.结果表明:加入Fe2O3、SiO2后TiO2仍然保持完整的锐钛型,抑制了TiO2晶粒的增长,且加入Fe2O3后TiO2的吸收波长发生了"红移".Fe2O3/SiO2/TiO2光催化性能、亲水性能优于SiO2/TiO2、Fe2O3/TiO2及单-TiO2膜.     

Engineering solid oxide fuel cell electrode microstructure by a micro-modeling tool based on estimation of TPB length

In this study, a typical solid oxide fuel cell (SOFC) electrode microstructure is numerically optimized in terms of the volume fraction of the catalyst, electrolyte and pore phases via a novel tool based on Dream.3D for the synthetic microstructure reconstruction and COMSOL Multiphysics® Modeling for visualizing and computing three/triple phase boundaries (TPBs). First, the properties of the representative volume element are studied by a parameter independence analysis based on the average particle size. The results indicate that the size of the representative volume element should be at least 10 times greater than the largest average particle size in the microstructure, while the number of mesh elements should be selected such that the smallest average particle size in the system is divided into at least 5. The method is then validated with the available studies in the literature and seems to agree well. Therefore, numerical reconstruction of SOFC electrodes by the proposed method is found to be a very useful tool in the viewpoints of accuracy, flexibility and cost. Finally, SOFC electrode microstructures having the same particle size distribution of an average particle size of 0.5 μm for each phase but with various phase volume fractions are generated and the resultant TPBs are computed similarly. It is found out that the volume fraction of each phase should be close to each other as much as possible to maximize the active TPB density and among the cases considered, the highest active TPB density of 9.53 μm/μm³ is achieved for an SOFC electrode including 35 vol% catalyst, 35 vol% electrolyte and 30 vol% porosity. The active TPB density is also found to be around 93% of the total TPB density.     

Coal char particle secondary fragmentation in an entrained-flow coal-water slurry gasifier

Coal char particle size in the gasifier has an influence on the carbon conversion, gasifier slagging as well as the particle matter content in raw syngas. The particle size distribution in a bench-scale opposed multi-burner (OMB) gasifier illustrated that the secondary fragmentation behavior exists in the entrained-flow gasifier after the particles moving from high temperature impinging flame region to the gasification chamber outlet region. Particles larger than 200 μm in the impinging flame region have porosity structures with fragile shapes. Particle size distributions under different oxygen to carbon ratios (O/C) also indicate that there is an obvious fragmentation while the particle size is larger than 200 μm. As long as the coal char particles move from the impinging flame region towards the gasification chamber outlet region, the secondary fragmentation is probably taken place as a result of percolative fragmentation, undergoing gasification reactions and thermal stress. However, thermal stress fragmentation only has an influence on the particle sizes larger than 350 μm according to the calculation by a simplified mathematical model.     

高炉瓦斯泥精细还原实验研究

对某钢厂2,3号高炉瓦斯泥进行了XRF-荧光、XRD物相、粒度、化学分析得知：平均锌质量分数为3.64％,铁质量分数为30.95％;平均粒度为15.555 μm,适合采用精细还原技术予以还原.实验室条件下利用纯H2对烘干后的粉尘还原结果表明：还原后残余物金属化率80％以上,脱锌率88％以上;最佳实验条件：还原温度980℃,还原时间4h,金属化率可达92.01％,脱锌率可达99.61％.还原后物料不发生烧结,且残余物与挥发产物都可再次利用,为高炉粉尘再资源化提供一条解决途径.     

Moving bed syngas conditioning: Modelling

This paper presents a modelling approach for simulating tars and particulate (dust) removal in a moving bed heat exchange filter (MBHEF) in order to satisfy gas requirements of end-use syngas applications: engines and turbines. The two-dimension, adiabatic, steady-state proposed model accounts for two-phase (gas and solid) and neglects conduction and mass diffusion. Tars condensation is modelled through representative tar class lumps: phenol (class 2), naphthalene (class 4), pyrene (class 5). The model also considers tar concentration influence on the tar dew point. The filtration model is taken from literature. A sensitivity analysis is performed varying the particle size and the superficial gas velocity. Maps of temperature and tars abatement efficiency are presented. The simulation results indicate the feasibility of the use a MBHEF as tars removal equipment benefiting its advantages against others gas-cleaning methods with acceptable pollutant removal efficiencies, ranging 88–94% for ranges studied. Results also point out low gas velocities (0.5-1 m/s) and high particle size (400–700 μm) for reducing operational costs in MBHEFs with compact size.     

Development of selective Pd–Ag membranes on porous metal filters

Metallic supports with sufficient surface quality to achieve highly selective thin Pd–Ag membranes require specific pre-treatments, are not readily available on the market and are generally very expensive. To reduce costs, rough and large media grade Hastelloy X filters have been acquired and pre-treated via polishing and chemical etching. The loss in gas permeance given by the polishing treatment proved fully recovered after chemical etching. A method to fill the large pores of the filters via aspiration of α-Al₂O₃ water-powder suspension has been applied and characterized via imaging of the filled pores, inferential statistics, and capillary flow porometry measurements. The most suitable filler particle size for pore size distribution reduction has been identified as 18 μm, while a 5 μm filler proved optimal for further pore morphology improvement. The wide pore size distribution of the filters has thus been reduced up to 200 nm by filling with α-Al₂O₃ particles of decreasing size, similarly to the ceramic supports used for thin Pd–Ag membranes deposition. A boehmite based interdiffusion barrier has been deposited, achieving further surface roughness reduction. A highly H₂ selective membrane has been obtained via simultaneous Pd–Ag plating on the pre-treated filter.     

Oxidation kinetics of micron-sized aluminum powder in high-temperature boiling water

A new efficient method of hydrogen, heat and aluminum oxide/hydroxide co-production is proposed. Only micron-sized aluminum powder (without any chemical activation) and usual water are used as initial reagents. For aluminum to be effectively oxidized, water is converted into the high-temperature boiling state that creates high pressure inside oxidation reactor. Paper describes the oxidation kinetics of aluminum micron powder in high-temperature boiling water depending on powder size and reactor temperature (pressure). Kinetic experiments were carried out using four types of aluminum powders with different dispersity. Due to kinetic experiments it was established that micron-sized aluminum powder intensively oxidizes in boiling water at temperatures above 230 °C. Aluminum powders with average particle size of 4.1 μm, 7.2 μm and 22.5 μm were fully oxidized at 296 °C, 308 °C and 350 °C respectively. Aluminum powder with average particle size of 77.5 μm after 10 min staying under about 364 °C was 95% oxidized. Reaction times for 4.1 μm, 7.2 μm and 22.5 μm aluminum powders decreased from 870 s at 237 °C to 33 s at 359 °C, from 800 s at 273 °C to 41 s at 355 °C and from 780 s at 286 °C to 66 s at 350 °C respectively. Aluminum oxidation product X-ray analysis showed that aluminum oxidized to aluminum hydroxide AlOOH - boehmite. Microstructure analysis showed that micron-sized aluminum powder oxidation product represents nano-sized aluminum hydroxide.     

燃用宽筛分煤循环流化床锅炉燃烧模拟计算

建立了循环流化床锅炉炉膛颗粒燃烧和脱硫反应模型。该模型考虑了炉膛下部为高颗粒浓度的密相区和上部为低颗粒浓度稀相区的特征,模拟计算给出了烟气温度,热流密度和各气体成分（Ｏ２,Ｃ２Ｏ,ＣＯ,Ｈ２Ｏ和Ｓ２Ｏ）的轴向分布,模拟计算结果的趋势是合理的。     

冷却速率对钢中MnS+Al_2O_3复合夹杂物包裹率的影响研究

通过实验室试验研究钢中MnS+Al_2O_3复合夹杂物的生成以及不同冷却速率对MnS+Al_2O_3复合夹杂物包裹率的影响。结果表明:被推动到钢液凝固前沿的Al_2O_3,会为MnS析出提供异质形核质点;随着冷却速率的增加,复合夹杂物的尺寸从4μm降至2.5μm左右,MnS+Al_2O_3复合夹杂物包裹率逐渐降低。本次试验研究为得到较优包裹程度的实验条件以及进一步改善钢材性能提供一定的理论分析。     

Magnesium and iron loaded hollow glass microspheres (HGMs) for hydrogen storage

The development of a safe and efficient method for hydrogen storage is essential for the use of hydrogen with fuel cells for vehicular applications. Hollow glass microspheres (HGMs) have characteristics suitable for hydrogen storage and are expected to be a potential hydrogen carrier to be used for energy release applications. The HGMs with 10–100 μm diameters, 100–1000 Å pore width and 3–8 μm wall thicknesses are expected to be useful for hydrogen storage. In our research we have prepared HGMs from amber glass powder of particle size 63–75 μm using flame spheroidisation method. The HGMs samples with magnesium and iron loading were also prepared to improve the heat transfer property and thereby increase the hydrogen storage capacity of the product. The feed glass powder was impregnated with calculated amount of magnesium nitrate hexahydrate salt solution to get 0.2–3.0 wt% Mg loading on HGMs. Required amount of ferrous chloride tetrahydrate solution was mixed thoroughly with the glass feed powder to prepare 0.2–2 wt% Fe loaded HGMs. Characterizations of all the HGMs samples were done using FEG-SEM, ESEM and FTIR techniques. Adsorption of hydrogen on all the Fe and Mg loaded HGMs at 10 bar pressure was conducted at room temperature and at 200 °C, for 5 h. The hydrogen adsorption capacity of Fe loaded sample was about 0.56 and 0.21 weight percent for Fe loading 0.5 and 2.0 weight percentage respectively. The magnesium loaded samples showed an increase of hydrogen adsorption from 1.23 to 2.0 weight percentage when the magnesium loading percentage was increased from 0 to 2.0. When the magnesium loading on HGMs was increased beyond 2%, formation of nano-crystals of MgO and Mg was seen on the HGMs leading to pore closure and thereby reduction in hydrogen storage capacity.     

A numerical investigation on the hydrogen reduction of wüstite using a 2D mesoscale method

The reduction of wüstite (FeO) is the most difficult step in the multi-step of iron oxides, and the basic characteristics of the hydrogen reduction of FeO are particularly important for the low-carbon development in metallurgy. In this work, the hydrogen reduction of pure FeO pellets was studied numerically by a 2D mesoscale method, which was further developed based on the lattice gas model. The method employed the directional probability and reaction probability to describe gas diffusion and reaction, respectively. The method was firstly validated by comparing with experiments reported by Usui et al. Then, the influence of reaction temperature, particle size, and porosity on the hydrogen reduction of FeO was conducted. The results demonstrated that the reaction rate increased with increasing temperature, increasing porosity, and decreasing particle size. The reaction mechanism depended on FeO pellet radius and porosity, it was boundary reaction at smaller radius (80 μm) or smaller porosity (0.210).