炭分子筛的无粉尘化技术研究

本文提出了一种可有效提高空分用炭分子筛的耐磨强度，去除其表面浮灰的方法。将原料炭分子筛在一定浓度的酚醛树脂有机溶液中浸渍３ｈ．沥干后放入电热转炉内在Ｎ２气中保护下，以一定的升温速率加热到３００～７００℃并恒温一定时间，冷却到室温，炭分子筛的表面即被一层致密的、孔隙结构发达的、带金属光泽的有机膜所包覆。有机膜的存在基本不影响分子筛的原有空分性能，但消除了炭分子筛的表面浮灰，并显著地提高了其耐磨强度。

转化气蒸汽发生器粉尘化腐蚀与对策

转化气蒸汽发生器是制氢装置的核心设备,其金属粉尘化腐蚀在运行中时有发生（通常在设计中被忽略）,引起低合金钢或普通不锈钢的严重腐蚀.粉尘化腐蚀仅发生在有CO存在的还原性气氛中,腐蚀严重部位的温度一般为482～ 648℃,主要发生在转化气蒸汽发生器上.针对设备粉尘化腐蚀现状,分析了粉尘化腐蚀的原因和影响因素;比较了各种材料对抗粉尘化腐蚀的能力,根据粉尘化腐蚀的程度,采用Inconel600,Inconel601和Inconel693不同等级的耐蚀材料来实现抗腐蚀的目的,并讨论了在设备结构设计上防止金属粉尘化腐蚀的问题,对高温转化气接触的管板、换热管等金属元件采取了降低局部高温部位温度,使其尽量低于粉尘化腐蚀发生的温度范围等措施,为转化气蒸气发生器的设计提供参考.

空气干燥器的结构对干燥剂粉尘化的影响

目前干燥剂粉尘化问题已成为影响双塔干燥器推广的关键，本文着重分析了双塔空气干燥器干燥剂粉尘化的原因，提出了防止干燥剂粉尘化的改进措施。

煤矿综放工作面高压雾化降尘对粉尘颗粒微观参数影响规律分析

喷嘴高压雾化降尘是综放工作面首要防尘方法。对于喷雾前后粉尘浓度的降低情况研究较多,而忽视了喷雾前后尘粒的粒度、粒径分布、形状系数、比表面积等颗粒微观参数的变化情况。采用显微颗粒图像分析法对生产现场喷雾降尘前后各主要作业地点的粉尘进行了微观参数测定。结果表明：喷雾降尘前后,各采样点的D10,D25,D50,DP,XNL,XNS一般在1.0～7.0μm之间小幅度变化,但D75,D90,D100,XNV,XLS,XLV,XSV,XPV却在3.3～56.8μm之间大范围变化;粉尘粒度变化与喷嘴雾化效果的关系为雾化效果越好,粉尘粒度则变得越大,反之亦然;喷雾降尘对粉尘的形状系数和比表面积影响较小;雾化降尘前后,工人主要作业区域呼尘所占比例及其4种粒级频率分布、累计分布较大幅度降低;除粉尘浓度外,还应将粉尘粒度及不同粒径粉尘颗粒的频率分布与累计分布的变化情况作为考核喷嘴雾化降尘效果的重要依据。

转化炉进出口管系及合成气余热锅炉局部材料失效机理及预防措施浅谈

针对国内外近15年频繁出现的转化炉进出口管道和工艺合成气余热锅炉局部材料断裂、穿孔、减薄等现象,文章分别从入口集气管应力释放裂纹、出口冷壁集气管高温氢腐蚀、工艺合成气余热锅炉CO金属粉尘化等方面进行分析,对材料失效机理、工程应用、预防手段等进行了简要阐述。分析认为,合理的选材、焊接、热处理、无损检测在一定程度可以预防或减轻以上材料失效现象。

地震诱发高速黄土滑坡的机理研究

针对１９２０ 年海原大地震（ Ｍｓ ＝ ８ ．５） ，１７１８ 年通渭大地震（ Ｍｓ ＝ ７ ．５） 和１６５４ 年天水大地震（ Ｍｓ ＝ ８ ．０） 等诱发的高速黄土滑坡所出现的种种现象与特征，提出了一种地震诱发高速黄土滑坡的机理———黄土体解体、斜抛和粉尘化效应。通过动力变形分析导出了黄土滑体斜抛运动的全过程及滑速、滑距公式。以海原大地震时，西吉县（１０°区） 回回川高速黄土滑坡为例，对这些公式进行验证，结果与实际情况相符。

Existing state of potassium chloride in agglomerated sintering dust and its water leaching kinetics

In order to examine the leaching rate of potassium chloride from the sintering dust by water,surface morphology and inner structure of the dust,especially the existing state of potassium chloride,were observed by scanning electron microscopy（SEM） and linear scanning technique via energy dispersive spectroscopy（EDS）.The characterization shows that the sintering dusts are mostly porous composites or agglomerates of the fine dust particles with size less than 10 μm,and the potassium chloride and sodium chloride particles are partly covered by other water insoluble matters in the dust which consist of elements iron,calcium and etc.Exposure of potassium chloride in the agglomerated dust matrix of this kind suggests that the leaching can be simply perceived as the dissolution of water soluble matters in the dust.On-line monitor of specific electrical conductivity of the leaching system verifies the prediction that leaching kinetics of potassium chloride from the sintering dust fits dissolution model well.Leaching equilibrium can be reached within 5 min with potassium leaching ratio more than 95%.

Water leaching kinetics and recovery of potassium salt from sintering dust

Surface morphology and inner structure of the dust were observed by ICP-AES, SEM-EDS and XRD to examine the strengthening measures of leaching potassium salt from the sintering dust by water. The results showed that the main component of the sintering dust was iron-oxygen compound, with KCl adsorbed on its surface. Leaching experiments showed that the KCl in the ESP dust could be separated and recovered by water leaching and fractional crystallization. The yield of K-Na vaporized crystalline salt was 18.56%, in which the mass fractions of KCl, NaCl, CaSO4 and K2SO4 were about 61.21%, 13.40%, 14.62%and 10.86%, respectively. The leaching kinetics of potassium salt from the sintering dust fits the external diffusion model well. The leaching speed and the leaching rate of the potassium salt can be increased by increasing the leaching temperature, strengthening the stirring speed and increasing the liquid-solid ratio.

Zinc leaching from electric arc furnace dust in alkaline medium

Physical and chemical properties of electric arc furnace （EAF） dust from Tianjin seamless Pipe Company were measured and analyzed. The zinc leaching tests in alkaline medium were carried out under variation of leaching agent concentration, leaching temperature, leaching cumulative time and solid-to-liquid ratio. The thermodynamics and kinetics of the zinc leaching process were also analyzed. The results show that the EAF dust contains 10% （mass fraction） zinc and the median particle size is 0.69 μm. The zinc recovery of 73.4% is obtained tinder the condition of 90 ℃, 6 mol/L NaOH, and 60 min leaching time. With the increase of concentration of NaOH and the cumulative time, zinc leaching will be significantly increased. The kinetics study demonstrates that the leaching reaction is chemically controlled and the reaction activation energy is 15.73 kJ/mol.

Simulation on dissolute and dust dispersion in comprehensive mechanized heading face with forced-exhaust ventilation

According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model to solve two-phase flow of gas and particles in dust space with eulerian-eulerian method and eulerian-lagrangian method. Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm. Moreover, numerical simulation of dust concentration in fully mechanized caving face was carded out by using Fluent software. Finally, when in forced-exhaust ventilation circumstance, drawer type fan drum have less dust absorption, and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head, and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m. Dust are more focused on relative side（in the range about y from 0 to 2 meter） of roadway space of press-ventilated fan drum, especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration. These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.

Optimization of selective leaching of Zn from electric arc furnace steelmaking dust using response surface methodology

The aim of this work is to investigate and optimize the effects of the leaching parameters on the selective leaching of zinc from electric arc furnace steelmaking dust （EAFD）. The response surface method was applied on the basis of a three-level Box–Behnken experimental design method for optimization of selective leaching parameters of zinc from EAFD. The leaching recoveries of zinc （YZn） and iron （YFe） were taken as the response variables, where the concentration of sulphuric acid （X1, mol/L）, leaching temperature （X2, °C）, leaching time （X3, min）, and liquid/solid ratio （X4, mL/g） were considered as the independent variables （factors）. The mathematical model was proposed. Statistical ANOVA analysis and confirmation tests were applied. A maximum of 79.09% of zinc was recovered while the minimum iron recovery was 4.08% under the optimum conditions of leaching time 56.42 min, H2SO4 concentration 2.35 mol/L, leaching temperature 25 °C and liquid/solid ratios. By using ANOVA, the most influential factors on leaching of zinc and iron were determined as H2SO4 concentration and leaching temperature, respectively. The proposed model equations using response surface methodology show good agreement with the experimental data, with correlation coefficients （R2） of 0.98 for zinc recovery and 0.97 for iron recovery.

Research on the Inert Dust against Phosphine Resistance of Cryptolestes Ferrugineus

Laboratory tests were carried out in order to evaluate the efficacy of five inert dust （Puliangtai, G-1, G-2, G-3 and G-4） against the high level phosphine resistance Cryptolestesferrugineus （Stephens）. The relative phosphine resistance of two strains of Cryptolestesferrugineus （Stephens） was measured by the method of knockdown at 2 mg/L of phosphine. The insects were exposed to the five inert dust on filter paper inside petri dishes for 1 day at 30 ±1℃and 65 ±1% relative humidity. Then, the adults were held for 4 days with food at the same conditions without inert dust in surface bioassay. Also, they were placed in 25 ±1℃ and 65 ±1% relative humidity in grain bioassay. In surface bioassay, two strains （JXCF and YYCF） ofCryptolestesferrugineus （Stephens） were susceptible to the five inert dust at 0.08 g/m2 and 0.1 g/m2. G-3 appeared the most effective treatment against both strains, since its efficacy was 3-6 times higher than the other four inert dust tested. YYCF strain was more susceptible than JXCF, with 1-4 times higher mortality level. This research indicated that inert dusts were effective on phosphine-resistance Cryptolestesferrugineus （Stephens） populations.

Effects of atomization parameters of dust removal nozzles on the de-dusting results for different dust sources

In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.

Micro-organic dust combustion considering particles thermal resistance

Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.

Geochemical studies on the source region of Asian dust

The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world＇s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.

Sand dunes as potential sources of dust in northern China

While saltation bombardment of sand grains on a fine substrate can produce considerable dust, the well-sorted nature of sand dunes tends to preclude them from consideration as major dust sources. Recent research, however, has revealed that sand dunes can, in some cases, be large sources of dust. We used the PI-SWERL(Portable In-Situ Wind Erosion Laboratory) to measure in the field the potential of sand dunes and other desert landforms to emit particulate matter <10 μm(PM-10) dust in the Tengger, Ulan Buh, and Mu Us deserts of northern China. Combined with high resolution particle size measurements of the dune sand, an assessment of sand dunes as a dust source can be made. Large active transverse dunes tend to contain little to no stored PM-10, yet they produce a low dust flux. Coppice dunes stabilized by vegetation contain appreciable PM-10 and have very high dust emission potential. There is a positive correlation between the amount of PM-10 stored in a dune and its potential dust flux. Saltation liberates loose fines stored in dunes, making them very efficient dust emitters compared to landforms such as dry lake beds and washes where dust particles are unavailable for aeolian transport due to protective crusts or sediment cohesion. In cases where large dunes do not store PM-10 yet emit dust when active, two hypotheses can be considered:(1) iron-oxide grain coatings are removed during saltation, creating dust, and(2) sand grains collide during saltation, abrading grains to create dust. Observations reveal that iron oxide coatings are present on some dune sands. PI-SWERL data suggests that low dust fluxes from dunes containing no stored dust may represent an estimate for the amount of PM-10 dust produced by removal of iron oxide coatings. These results are similar to results from dunes in the United States. In addition, PI-SWERL results suggest that dust-bearing coppice dunes, which cover vast areas of China's sandy deserts, may become major sources of dust in the future if overgrazing, depletion of groundwater, or drought destabilizes the vegetation that now partially covers these dunes.

探讨尘肺病分类的合理性

粉尘不同,诊断的尘肺病种类不同。我国现有尘肺病13种分别对应不同的粉尘或工种。ILO(国际劳工组织)的专家们普遍认为区分致纤维化矿物粉尘如二氧化硅和石棉和非致纤维化矿物粉尘如云母和石墨是重要的。我国的专家持不同的观念,认为吸入并贮留在肺内的任何粉尘均能引起异物反应,长期贮留在肺内的异物均可以导致非特异性的纤维性增生。从各种尘肺的病理特点以及普通型间质性肺炎的病理改变中发现,二氧化硅和石棉所致肺间质纤维化最具特点。二氧化硅可以致肺组织内形成同心圆排列的玻璃样变。石棉粉尘主要的病理改变是导致胸膜斑的形成。其他各种粉尘多是在肺内引起多发性粉尘灶,可能是这些粉尘在局部潴留而形成继发性纤维化。将矿物性粉尘区分为致纤维化和非致纤维化2个大类,并设定合理的开放性目录,为职业病诊断提供便利。国际癌症组织(IARC)将石棉和石英列为人类已知的致癌物,致纤维化粉尘的概念突出了游离二氧化硅和石棉的危害。癌症比肺间质纤维化更具有致死性;致纤维化粉尘比非致纤维化粉尘更具侵入性。

Effects of different product phases in aluminum dust detonation modeling

Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and fractions.Recent experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the gaseous one was considered before.To resolve this drawback,we study the effects of different product phases on the detonation parameters with the hybrid combustion model proposed recently.Numerical results demonstrate that the assumption of gaseous product induces high velocity and pressure,while the assumption of solid product induces low velocity and pressure.To clarify how close-to-experiment results have been obtained with one phase assumption,we revisit previous studies and analyze the models.The inconsistency between the product phase and heat release is found,and then one model with variable heat release dependent on the product phase is proposed.Then simulations with both the gaseous and solid products are carried out,and results reveal the necessity of establishing a relationship between the heat release and reaction products.

Effect of aluminium dust on secondary organic aerosol formation in m-xylene/NO_x photo-oxidation

As an important anthropogenic volatile organic compound(VOC), m-xylene has attracted numerous attentions due to its potential in secondary organic aerosol(SOA) formation. In this study, effects of aluminium dust seeds(boehmite and alumina) on SOA yield and aerosol size in m-xylene/NOx photo-oxidation were investigated in a 2 m3 smog chamber at 30°C and 50% relative humidity. Compared to the seed-free system, the presence of aluminium seeds resulted in an increase in the SOA yield, and also enhanced the O3 concentration in the chamber. The photolysis of O3 is a major source of OH radical, which is the most important oxidant of m-xylene. The increase in O3 concentration could result in the generation of more OH radicals, and finally contribute to the SOA formation. Seed particles influence the SOA size mainly by acting as condensation nuclei. Semi-volatile organic compounds(SVOCs) were condensed onto these nuclei, resulting in the increase in SOA size. However, when aluminium seeds with high concentrations were introduced into the system, SVOCs that had been condensed onto each particle were dispersed by these seeds, leading to the reduction in aerosol size.