磷石膏和硫化钙反应过程的熔融特性研究

为探讨影响磷石膏分解制硫酸生产过程中回转窑内结皮、结圈和粘结堵塞等问题的主导因素,以磷石膏和硫化钙为原料,采用微机灰熔融性测定仪研究了不同添加剂和反应气氛对CaSO4和CaS固-固反应中熔融软化温度(ST)的影响。结果表明,提高磷石膏制硫酸反应中熔融软化温度的有效添加剂是高岭土和SO2、CO2、N2的混合气氛,而起助熔作用的添加剂是SiO2、AlPO4、FePO4.2H2 O、Na2 SiF6等。     

不同气氛对硫铁矿与磷石膏反应过程软化温度的影响研究

不同气氛会影响硫铁矿还原磷石膏制酸反应体系的软化温度,从而导致回转窑内产生结圈和黏结堵塞等问题。先利用热力学软件计算了不同气氛对硫铁矿与磷石膏固-固反应体系熔融液含量、产物迁移过程的影响。通过微机灰熔点测定仪对二硫化亚铁与硫酸钙物质的量比以及气氛条件对反应体系软化温度的影响进行了实验验证。结果表明,反应体系软化温度随着二硫化亚铁与硫酸钙物质的量比的增加而降低,气氛条件对反应过程固相产物迁移过程的影响不大;相比于100%氮气气氛,在86%氮气+7%二氧化碳+5%二氧化硫+2%氧气的混合气氛下,磷石膏和硫铁矿反应体系熔融液含量少、软化温度高。     

硫铁矿还原磷石膏反应热力学分析

采用HSC Chemistry热力学软件对硫铁矿还原磷石膏工艺进行了相关计算,探索了反应分解温度、不同温度下物相组成,并与相同条件下的硫铁矿还原磷石膏实验结果进行了比较。XRD分析结果表明,硫铁矿还原分解磷石膏的主要产物为Ca2Fe2O5和CaO,热力学计算结果与实验结果一致,表明采用化学热力学平衡分析方法可作为硫铁矿还原磷石膏反应特性研究的指导性方法。     

磷石膏复分解法制备硫酸铵的研究

以磷石膏和碳酸铵为原料,采用复分解法制备硫酸铵。考察了原料物质的量比、反应温度、反应时间、液固比、搅拌器转速等因素对磷石膏制备硫酸铵的影响。通过实验,确定了最佳工艺条件:原料液中CO2-3与SO2-4物质的量比为1.5,反应温度50℃,反应时间90 min,液固比为5.0,搅拌器转速为200 r/min以上。在此条件下,磷石膏制备硫酸铵转化率大于90.0%,产品质量分数大于98.0%。     

副产磷石膏制造硫酸和水泥

近两年内德意志民主共和国进行了副产磷石膏制酸和水泥的研究,最近并发表了有关操作数据。 生产过程:磷石膏制酸及水泥主要是硫酸钙和碳反应生或SO_2,其反应: CaSO_4+2C→CaS+2CO_2 (1) 3CaSO_4+CaS→4CaO+4SO_2 (2) 总反应: 4CaSO_4+2C→4CaO+4SO_2+2CO_2(3) 在窑内(1)式的适宜温度900℃,(2)式的温度为1200℃。外加粘土、砂和氧化铁反应生成水泥熟料。 砂及粘土在进入转窑之前必须进行干燥,而焦炭和氧化铁(硫铁矿渣)一般不     

石膏资源的开发和利用

本文介绍了石膏的资源状况与种类。以石膏为原料开发新品种及其新工艺的途径,以及应用领域的开拓.前言石膏(CaSO_4·2H_2O)及硬石膏 CaSO_4是一类分布较广的矿物,将石膏在不太高的温度下锻烧后,就可制     

磷石膏复分解制硫酸铵的工艺研究

采用单因素试验,进行了以磷石膏为原料复分解反应制备硫酸铵的试验,考察了反应时间、反应温度、加料速度、液固比、物料比[n(CO2-3)/n(SO2-4)]和搅拌器转速对反应的影响.通过正交试验优选,确定了最佳工艺条件:反应时间为100 min,反应温度为45℃,搅拌器转速为150 r/min,物料比[n(CO2-3)/n(SO2-4)]为1.15,液固比(质量计)为2.9,加料速度为36g/min.在最佳工艺条件下,磷石膏中SO2-4的平均转化率为98.98%.     

CaF2作用下磷石膏还原分解过程的动力学特性

借助热分析手段,研究了磷石膏在矿化剂作用下还原分解过程的反应特性,探讨了矿化剂CaF2对磷石膏高温分解过程的影响.矿化剂的引入可以显著降低磷石膏分解的起始温度,有效提高磷石膏还原分解的反应活性,加入3wt％ CaF2能使磷石膏的分解温度降低约200℃.矿化剂与磷石膏混合体系在950℃下分解时,主要产物是Ca2SiO4,也存在含氟的共熔体,表明加入CaF2能促进磷石膏的固相分解反应.利用Coats-Redfem法获得磷石膏还原反应的动力学方程,计算得到其表观活化能E=380.06 kJ/mol.     

磷石膏制备高纯硫酸钙的循环工艺

为高效利用磷石膏中丰富的CaSO_4资源,采用化学试剂循环利用工艺,以磷石膏为原料,制备了高纯度硫酸钙产品。首先用NaOH溶液分解磷石膏,将其中的SO_4~(2-)分离出来,得到Na_2SO_4溶液;余下的钙渣再用盐酸溶液溶解其中的Ca~(2+),除去酸不溶渣,得到CaCl_2溶液;将硫酸溶液加到CaCl_2溶液中,得到高纯度硫酸钙沉淀和盐酸溶液。盐酸溶液可循环用于溶解钙渣中的Ca~(2+)。硫酸和氢氧化钠溶液则可通过电解Na_2SO_4溶液制得。最终得到的硫酸钙产品纯度可达99.72%,CaSO_4回收率为85.99%。     

CO_2气氛下褐煤还原磷石膏的TG-FTIR研究

为了实现磷石膏的资源化利用,采用热重-傅里叶红外光谱联用技术(TG-FTIR),在CO_2气氛下对曲靖褐煤还原磷石膏的反应特性进行了研究。通过热重-红外联用技术分别对固体产物和气体产物的生成规律进行分析。结果表明,CO_2气氛下褐煤的加入可以明显降低磷石膏的还原分解温度,褐煤还原磷石膏主要经过三个过程:水分析出过程、褐煤热解过程、褐煤和CO与磷石膏的还原过程,且第三个过程的反应产物随Ca/C摩尔比的不同而变化。当Ca/C=0.5时,主要固体产物为CaS,气体中SO_2的释放较少;当Ca/C=2时,褐煤与磷石膏反应生成CaS,此后生成的CaS又可与磷石膏发生固-固反应生成CaO,气体中SO_2释放量较高,为分解磷石膏制硫酸联产水泥提供一定的可能。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。