电煅无烟煤微观结构特征研究

以国外某矿区无烟煤为原料,采用工业用高温电阻炉制备了电煅无烟煤A(～1 700℃)和电煅无烟煤B(～1 900℃)。用孔结构分析仪、X射线衍射仪、真密度测试仪及焦粒电阻率测试仪分别研究了电煅无烟煤A和电煅无烟煤B的孔结构、石墨化度、真密度和电阻率等。研究表明:电煅无烟煤孔隙形状以裂隙状为主,同时含有少量瓶颈形孔,并且经过更高温处理,电煅无烟煤B出现更多裂隙,部分孔壁坍塌,使得其孔比表面积和孔容显著增大,孔连通性变好。更高的煅烧温度有利于挥发分、水分和杂质分子的排除,使碳原子排列趋向于芳香结构,石墨化程度进一步提高,真密度增大,电阻率降低。     

提高电极糊质量以满足大型矿热炉发展的需要

1.概况电冶金工业用的自焙电极(Soderberg电极)在我国炭素工业称为电极糊。电极糊生产工艺过程比较简单,工序又少。往往不被人们所重视。五十年代开始生产的标准糊(低档电极糊)作为开放式矿热电炉生产需要,一直保留到现在。六十年代末期研制的密闭糊,实际质量水平也不太高。在配方选择上仍然采用低温煅烧无烟煤,电阻率较高。由于煤质较差,     

1350kVA电煅炉的热平衡

无烟煤在用于炭素制品生产之前必须经过煅烧 ,以除去其中的挥发分 ,并使无烟煤的电阻率降低。研究表明 ,在用于高炉和铝电解槽砌筑时 ,就炉衬寿命而言 ,电煅无烟煤炭块优于煤气煅烧的无烟煤炭块 ,这是由于电煅无烟煤与煤气煅烧的无烟煤相比 ,平均煅烧温度高 ,有较低的电阻率和气化反应率 ,较高的真密度、抗碱金属侵蚀性和导热性[1] 。最近几年 ,随着国内炼铝工业的飞速发展 ,阴极炭块需求量猛增 ,一些中小型炭素厂相继建成了电煅烧炉 ,如今 ,电煅烧已成为炭块生产中的关键技术。电煅烧炉要消耗大量宝贵的电能 ,通常生产 1ｔ电煅无烟煤大约要…     

影响电煅无烟煤电阻率的几个因素

对电煅无烟煤电阻率与一次送电电流和温度之间的关系进行了试验研究，得到了它们之间的关系表面式模型，据此，可以在环境温度，炉壳温度变化不大的情况下，预测电煅无烟煤的电阻率，另外还分析了电阻率与真密度，原煤粒度分布，加排料量，煅烧区长度，电流密度之间的相关性，结果表明，电煅无烟煤电阻率及其分布与电流密度，煅烧区长度，原煤粒度分布，加排料量密切相关。     

阴极碳块材质改进及其粘结技术

铝用阴极碳块,长期以来,是用煅烧无烟煤作原材料,无烟煤中灰分含量要求5％以下。煅烧温度从1250～1350℃提高到2000℃左右,其目的是使煤中无定形碳部分的转化为石墨,这种高温煅烧煤可称之为半石墨质煤。     

特种密闭电极糊通过技术鉴定

<正> 包头第二化工厂与湖南大学、贵阳铝镁设计研究院共同研制,在包头第二化工厂用高温电煅烧无烟煤生产工艺生产的符合 QJ/BEH-02-201-91标准的特种密闭电极糊,经过小试、工业性试验和使用考核,证明产品性能达到引进的4.5万 t/a 全密闭电石炉使用要求。该项目在化工部科技司主持下于1992年3月6日在包头市通过技术鉴定。包头第二化工厂2.4万 t/a 电极糊项目是化工部“七五”专项,其中密闭电极糊1.4万 t/a,标准     

煅烧温度对无煤烟性质的影响

本文对无烟煤不同温度煅烧的结果进行了分析,初步讨论了无烟煤煅烧过程中挥发分的逸出及其百分组成,煅后料真密度、体积收缩、电阻率等的变化情况。     

罐式煅烧炉煅烧无烟煤时破损原因粗探

罐式煅烧炉以其烧损小 ,能耗低 ,煅烧质量好等优点广泛应用于炭素企业 ,其煅烧原料主要是延迟石油焦或延迟石油焦加少量沥青焦 ,但生产多灰产品 ,如各种糊类产品、炭块产品时 ,将要用到煅后无烟煤。用罐式煅烧炉煅烧无烟煤时 ,由于无烟煤灰分大 ,且炉子长期处于高温状态 ,使得灰分对炉子造成了严重的渣蚀 ,影响了炉子的使用寿命。下面对引起罐式煅烧炉破损进行了初浅的分析和探讨。1　硅砖性质及无烟煤特点罐式炉的煅烧罐壁是用硅砖彻成的 ,硅砖的主要成分是ＳｉＯ2 ,其含量在 93%以上 ,其耐火度为1690～ 1730℃ ,荷重软化点在 162 0～ 1670…     

电煅烧无烟煤——一项新生产技术

电煅烧无烟煤(ECA)好于燃气煅烧无烟煤(GCA),现在已被铝电解槽阴极炭块的寿命和高炉炉龄的实践所肯定。电煅烧炉已使用了许多年,然而,其高能耗和煅烧不均匀性是工艺本身存在的弱点,我们已开发了一项新生产技术,使无烟煤高温处理,其温度均匀性有明显改进。此新工艺,基于完整的掌握气—固相交换以及挥发物循环的新技术,有助于节约一笔可观的费用。即:电能从110kwh降低了50％;回收挥发物可使每吨电煅烧无烟煤节约相当于80kg燃料油。在质量和生产稳定性上的实际成果,将在炉技术中加以评述。     

1 350 kVA电煅烧炉炉芯电流偏移的调整

用高温煅烧无烟煤制造各类炭砖，具有膨胀性小，耐铁、钾侵蚀和高密封特性，因而目前广泛采用电煅炉煅烧无烟煤，以获得上述的原料。但由于电煅烧炉易偏流（电流偏离炉芯），因此造成炉内温度分布严重不均，部分无烟煤被石墨化，另一部分低炭化，这两种情况都使煅烧无烟煤失去半石墨质特性，因而调整电流的偏移在生产中是极为重要的。本文将对１３５０ｋＶＡ电煅烧炉电流偏移的调整方法作一小结。１电流偏移的原因及处理方案１．１电煅烧炉结构简介电煅烧炉工作参数见表１，结构见图１。１—四开口料仓；２—滑动闸板；３—夹持器；４—石墨…     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。