磁场形式及参数对单纤维捕集钢铁行业粉尘中PM_(2.5)性能影响

目前钢铁行业已成为大气污染防治的重点,为解决现有钢铁行业对于PM_(2.5)细颗粒难以捕集的难题,实现粉尘的超低排放.基于CFD-DPM(computational fluid dynamics-discrete phase model)方法对磁性纤维产生的磁场以及高梯度磁场等不同磁场形式下单纤维对钢铁行业捕集PM_(2.5)性能的影响进行研究,通过X射线衍射图谱分析可知钢铁行业生产过程产生的粉尘因含有Fe_3O_4以及单质Fe而具有磁特性,进而提出了利用磁场来增强单纤维捕集PM_(2.5)性能的方法.计算结果表明,在运动轨迹方面,磁性纤维产生的磁场会在纤维周围形成引力区,高梯度磁场会在纤维周围形成2个引力区和2个斥力区;在捕集性能方面,当粉尘粒径dp为0.5～1.0μm,入口风速v≤0.2 m·s~(-1)时,高梯度磁场下磁性纤维的捕集能力要强于单一磁性纤维的捕集能力,若磁场强度H=0.5 T,磁感应强度B=0.01 T,v=0.1 m·s~(-1),高梯度磁场可以使单纤维的捕集效率提高为传统单纤维捕集的28.32倍,若B=0.01 T,v=0.1 m·s~(-1),磁性纤维产生的磁场可以使捕集效率提高为传统单纤维捕集的4.037倍;在磁性纤维产生的磁场中,当磁感应强度B≥0.03 T时,磁性单纤维对PM_(2.5)的捕集效率随着入口风速的增加而减小,后趋于稳定,当B<0.03 T时,捕集效率随入口风速逐渐减小;捕集效率随粉尘粒径的增加而增大.而对于高梯度磁场,单纤维对PM_(2.5)捕集效率同样随着入口风速的增加而减小,当v>0.4 m·s~(-1)时,捕集效率为0,B越大,捕集效率下降越快;捕集效率随着粉尘粒径增大呈现先增加后减小的趋势.     

长沙冬季PM2.5、PM10中金属元素的浓度及分布特征

选取长沙县某商业区、居住区、对照区三个区域,研究该区域内的PM_2.5、PM₁₀浓度及其金属元素贡献率,结果表明,空气中PM_2.5、PM₁₀浓度总体呈现商业区>居住区>对照区的趋势,PM_2.5中贡献率最大的5类金属元素为Na、Ca、K、Al和Mg,重金属中贡献率最大的为Cu和Mn;PM₁₀中为Na、Ca、Fe、Al和Mg,重金属中贡献率最大的为Cu和Zn。PM_2.5、PM₁₀中含量最低的重金属元素都为As。     

冶炼厂室内空气PM2.5中金属元素的浓度分析

研究了冶炼厂车间、冶炼厂工作区和农家住宅区3个区域的一层室内空气中PM_2.5及PM_2.5中的Zn、Pb、Cu、Mn的月平均浓度和变化规律,结果显示,车间冶炼过程中产生的粉尘扩散到冶炼厂工作区时扩散稀释较为充分,并未明显导致工作区室内空气中的PM_2.5增加,且冶炼厂车间产生的PM_2.5对冶炼厂一层工作区PM_2.5中的Pb、Cu、Mn元素含量贡献较大。     

含锰高效吸附剂对公路施工现场扬尘及PM2.5吸附效果研究

研究以粉煤灰渣为原料,以高锰酸钾、氯化锰、氢氧化钠为改性剂,通过化学改性反应制备含锰的高效吸附剂Mn-FA,运用红外光谱、热重分析、等温吸附实验等手段,对吸附剂的物理性质进行表征,分别探究了其对不同大气污染颗粒物(PM₁₀、PM_2.5、TSP)的吸附性能。结果表明,Mn-FA高效吸附剂对公路施工现场扬尘及PM_2.5颗粒物有显著吸附作用。改性前的粉煤灰和锰改性后的Mn-FA吸附剂,比表面积较粉煤灰增大,为123.45 m²/g,孔容为0.865 cm³/g。吸附剂对大气颗粒物的吸附能的大小排序为PM_2.5>PM₁₀>TSP,分别为95%、90%、80%,能够大量吸附大气和灰尘中的颗粒物,针对与粒径较小的PM_2.5,吸附能力最大。经过改性的FA吸附能力显著增加,效率增加了50%,充分验证了,以锰为核心材料制备的高效吸附剂,在处理施工过程中产生的扬尘和大气污染物方面具有较好的效果,对于施工扬尘的治理具有参考...     

中位粒径对磁约束线板式ESP捕集性能的影响

针对静电除尘器(Electrostatic Precipitator,ESP)对细颗粒物捕集性能欠佳的现状,本文建立线板式ESP理论模型和结构模型,利用GAMBIT和FLUENT软件对不同中位粒径下的PM2.5除尘效率进行数值仿真,并比较有无磁约束和离子风作用对PM2.5捕集性能的差异.研究结果表明:线板式ESP对PM...     

TiO2对高铝高炉渣性能和结构的影响研究

随着国内各钢铁企业高炉配加经济性较高的高铝原料的增加,炉渣中Al₂O₃含量增加,渣铁流动性变差,给高炉冶炼带来一系列问题。以CaO-SiO₂-Al₂O₃-MgO-TiO₂五元渣系为研究对象,通过相图理论计算结合试验研究和炉渣结构分析,研究了高铝渣中不同TiO₂含量(低钛:5%,中钛:15%,高钛:25%)对高铝高炉渣黏度、熔化性温度的影响,并通过炉渣结构研究解析了影响炉渣物化性能的原因。结果表明:固定碱度R₂为1.25,TiO₂质量分数增加至25%过程中,炉渣熔化温度先下降后增高,当Ti0₂质量分数为7%时,炉渣液相析出相由斜长石类的钙铝硅酸盐(Ca₂Al₂SiO₇)转变为高熔点钛酸钙(CaTiO₃),其熔点为1975℃,炉渣熔化温度增加;TiO₂含量由低钛5%...     

热处理工艺对La0.85Ce0.15(NiMnAl)5.30贮氢合金相结构及电化学性能影响

本文研究了无钴La_0.85Ce_0.15(NiMnAl)_5.30贮氢合金在不同热处理工艺下相结构及电化学性能变化规律。衍射分析表明退火参数优化后的合金仍为CaCu5单相,温度升高后结晶度增加但活化性能变差;PCT测试结果显示920℃退火时吸氢量达到0.8902;温度升高后吸氢量呈现降低趋势,放氢压力也明显增加;经过980℃热处理8h后晶体结构改善明显,其吸放氢前后膨胀体积变化最小,抗粉化能力强。无钴合金熔点降低、温度升高后利于体相中元素扩散;活化性能降低的同时合金最大放电容量也有所降低。980℃制备合金电化学性能最优,同时具备较好的贮氢性能。     

Fe2O3微粉添加对MgO CaO系耐火材料烧结性能及 抗水化性能的影响

通过添加Fe2O3微粉的方法,研究了Fe2O3微粉对MgO CaO系耐火材料烧结性能和抗水化性能的影响。试验结果表明,添加Fe2O3微粉可以有效地促进MgO CaO系耐火材料的烧结,抑制其水化速度。当Fe2O3的添加量在0～3%时,随着Fe2O3添加量的增加,耐火材料试样的体积密度先增加后减小,显气孔率则先减小后增加,且两者均在Fe2O3为1%处出现极值。当Fe2O3的添加量在02%～05%的范围时,耐火材料试样的显气孔率和体积密度变化最明显。当Fe2O3添加量为1%时,将试样在温度为60 ℃、相对湿度为75%的条件下水化144 h后,其粉化率仅为146%。
     

Al2O3夹杂在DC06钢中的分布及对深冲性能的影响

连退DC06钢板表面发现线链状及翘皮缺陷,初步判断是非金属夹杂物经轧制后破碎造成。通过扫描电镜(SEM)观察两种缺陷处夹杂物的微观形貌,线链状缺陷处夹杂物多为不规则的块状,翘皮处夹杂物多为颗粒状。经统计发现两种缺陷处夹杂物尺寸(d)均较小,为显微夹杂物,1.5 μm≤d≤6.2 μm。通过能谱检测分析两种缺陷处夹杂物的成分,确定夹杂物类型为非金属夹杂物Al₂O₃。通过模拟微冲压试验可知,此尺寸级别的Al₂O₃夹杂造成的线链状缺陷对连退DC06钢板的冲压性能无明显影响。翘皮缺陷已对钢板外观造成很大影响,故不再考察其对冲压性能的影响。     

w(MgO)/w(Al2O3)对烧结矿成矿特性及冶金性能的影响

w(MgO)/w(Al₂O₃)(以下简称镁铝比)作为铁矿粉烧结过程的重要成分参数之一,对烧结过程的成矿特性及烧结矿冶金性能的改善意义重大。运用FactSage热力学软件理论计算了烧结体系的平衡物相组成及液相组分变化规律,随着镁铝比由1.07降低至0.67,烧结矿中液相、铁氧化物等优质物相含量增加,尖晶石等劣质物相含量下降。烧结杯试验探究了不同镁铝比烧结矿的理论物相组成、产质量指标、显微结构及冶金性能变化规律,结果表明,随着镁铝比由1.07降低至0.67,烧结速度由29.57 mm/min逐步提高至31.12 mm/min;成品率由62.89%提高至64.12%,并在镁铝比为0.77时达到最大值65.56%;转鼓强度由54.67%提高至60.27%,并在镁铝比为0.77时达到最大值64.67%;利用系数先减小后增大;固体燃耗逐渐降低,并在镁铝比为0.77时达到相对低值74.53 kg/t。随着镁铝比由1.07降低至0.67,烧结矿中铁酸钙含量先上升后降低,硅酸盐和磁铁矿含量变化较小,赤铁矿含量和孔洞量逐渐降低,镁铝比为0.77时达到最佳烧结矿物...     

CO2在钢铁工业资源利用现状

钢铁生产过程CO₂的资源利用问题将对我国CO₂减排任务的完成起到重要作用.以CO₂在钢铁工业中的资源化利用为出发点,分析了国内外CO₂气体作为反应气体、搅拌气体及保护气体等在钢铁生产过程中的应用现状. CO₂用作反应气体主要应用在BOF转炉炼钢、不锈钢生产及钢渣碳酸化处理;CO₂用作搅拌气体主要应用于转炉底吹、钢包搅拌及LF炉精炼;CO₂用作保护气主要应用在出钢、中间包及连铸等工序.利用CO₂用于钢铁生产具有成本低、热力学条件好、密度大、搅拌能力强及实现CO₂资源利用等优点,CO₂喷吹之后反应体系中CO₂的利用率需进一步研究.      

中国重点区域钢铁产业能耗和CO2排放趋势分析

钢铁产业是区域工业发展的重点,也是区域协调发展的重要因素。采用自下而上的方法建立了重点区域钢铁产业能耗和CO₂排放模型,分析区域特征对钢铁产业节能减排的影响。模型以2015年为基准年,基于粗钢产量预测结果,设置了与节能减排技术普及和生产结构调整相关的4个情景,用于分析2015—2030年国内重点区域钢铁产业的能耗和CO₂排放。结果表明,降低钢产量是区域钢铁产业节能和CO₂减排的根本措施。随着重点区域的粗钢产量进入峰值区,技术普及因素的节能贡献力将持续减少,生产结构调整的节能减排贡献力则逐渐增强,成为重点区域钢铁产业节能减排的关键红利来源。同时还可得出,对重点区域钢铁产业发展影响最大的区域特征是市场需求,经济产业政策和环保要求对钢铁产业发展的影响程度逐渐增强。未来重点区域钢铁产业的发展仍以市场需求为导向,新增产能更倾向于布局在水资源丰富、交通便利的地区。     

新形势下钢铁行业的节水应对策略

中国是一个人口大国,更是一个水资源严重匮乏的国家。有关资料显示,我国人均水资源拥有量不足世界平均水平的1/4,是全球13个最缺水国家之一,水资源紧缺成为我国水资源问题的常态。随着人们对物质消费需求的日益增长,对生活品质的日益改善,社会对水资源的需求也在持续增加,水危机也成为影响我国可持续发展的重要因素。     

Analysis of CO2 emission and mitigation methods in integrated iron and steel works

CO2 emission of the steel industry takes up a great proportion of the total emission of the world.It is necessary to reduce the CO2 intensity of steel products in order to save energy,protect the environment and keep a sustainable development in the steel industry.Based on the research of steel products’ life cycle inventory,those who conducted this research have focused on the analysis of CO2 emission factors and measures.Adopting the life cycle inventory model of a certain steelmaking site,together with the Tornado Chart,the researchers have identified significant factors,provided some explanation,and suggested some possible measures to reduce CO2 emission.The results have shown that the most important factors are the CO2 intensity of blast furnace gas (BFG), hot metal ratio of basic oxygen furnace (BOF) and the material utilization efficiency.Accordingly,some measures such as removing CO2 in BFG,decreasing the hot metal proportion in BOF,and improve material utilization efficiency in each process,may be taken to decrease CO2 emission.     

中国钢铁产业技术政策的演进特征解析

以政策针对性和政策实施时间为依据,将建国以来的钢铁产业技术政策进行阶段划分,有利于增强对该政策的全面理解,从宏观上把握政策的总体发展趋势;从钢铁产业技术政策演进的背景、措施、政策效果和政策核心等角度阐述各阶段的特征,正确评估政策实施的效果,有利于发现政策演进中的不足之处,为政策进一步的完善提供依据;在科学发展观的指导下,基于该政策的历史阶段特征,建立钢铁产业技术政策演进优化模型,指出钢铁技术政策应该并且能够朝着增强产业可持续能力的方向演进,以提升钢铁产业技术水平.     

Photocatalytic activity of cerium-doped mesoporous TiO2 coated Fe3O4 magnetic composite under UV and visible light

A novel kind of magnetically separable photocatalyst of cerrium-doped mesoporous titanium dioxide coated magnetite (Ce/MTiO2/ Fe3O4) was prepared and its activities under UV and visible light were reported. The catalysts with Ce/MTiO2 shell and Fe3O4 core were pre-pared by coating photoactive Ce/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with pre-cursors of ammonium ceric nitrate and TBT in the presence of Fe3O4 particles. The MTiO2 shell was for photocatalysis, the Fe3O4 core was for separation by the magnetic field and the doped Ce was used to enhance the photocatalytic activity of MTiO2. The morphological, struc-tural and optical properties of the prepared samples were characterized by Brunauer-Emmett-Teller (BET) surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of cerrium-doped content on the photocatalytic activity was studied and the result revealed that 0.5 mol.% Ce/MTiO2/Fe3O4 exhibited highest photoactivity. The photocatalytic activities of obtained photocatalysts under UV and visible light were estimated by measuring the degradation rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxi-dation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Ce/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by an external magnetic filed. So, the photocatalyst can be reused without any mass loss. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.     

Thermodynamics of Ca-CaF2 and Ca-CaCI2 systems for the dephosphorization of steel

Calcium is soluble in halide salts which can be used to remove phosphorus from steel as a phosphide ion. The activity and activity coefficient of calcium phosphide, and the equilibrium phosphorus distribution ratio between Ca-CaF₂ and Ca-CaCl₂ fluxes and pure solid iron were measured as a function of the Ca composition in the flux at 1350 °, 1400 °, and 1450 °. The Ca-Ca halide fluxes were equilibrated with pure solid iron and a Ag-Ca alloy in an iron crucible under an Ar atmosphere. The Ag-Ca alloy was used to maintain a constant chemical potential of calcium. Phosphorus distribution between between these fluxes and solid pure iron increased with increasing calcium activity and decreasing temperature. The activity coefficient of γ_{Ca 1.5 P} was calculated to be 36.6 at 1350 ° and 11.0 at 1450 ° for a calcium activity of 0.2 (wt pct Ca = 2.5) in the Ca-CaF₂; the activity coefficient increases with increasing Ca in the flux. In addition, the activity of Ca in the Ca-Ca halide fluxes was determined. The equilibrium phosphorus distribution ratio between Ca-Ca halide systems and molten chromium steel was calculated as functions of Cr and C contents of the metal and calcium activity in the flux at 1600 °C by using γ_{Ca 1.5 P} obtained in the present work. This ratio was found to be about 20 for 18 pct Cr stainless steel at 1600 °. Formerly a Graduate Student at Carnegie Mellon University