国内资料文摘

77087 废气硫化氢制硫脲宁波农药厂宁波中药制药厂浙江化工(1、2):54～55.1977 生产农药马拉硫磷时产生的硫化氢废气,污染环境。宁波农药厂与宁波中药制药厂互相协作,用石灰乳代替碱液,制成硫氢化钙,再用硫氢化钙与石灰氮反应,生产硫脲,为生产硫脲和硫化氢废气的综合利用闯出了一条新路。几年来利用废气硫化氢,已生产了硫脲200多吨。硫脲生产中废渣、废料经施用证明仍是很好的氮肥,硫脲废液尚有良好的除莠、杀虫效果。     

利用废石膏制备硫脲的新工艺研究

研究了利用废石膏制备硫脲的新方法,通过废石膏炭化焙烧制备硫化钙、碳酸化浸取制备硫氢化钙、硫氢化钙与石灰氮湿法反应制备硫脲.该工艺省却了传统硫脲合成过程中硫化氢制备环节.同时,考察了废石膏炭化焙烧的反应条件对硫化钙产出率影响的规律,提出废石膏高效利用的优化条件为:按废石膏与炭的质量比为1:2.5,管式炉中920 C条件下...     

硫化钙碳酸化制备硫氢化钙的工艺参数研究

研究了以磷石膏为原料烧制的硫化钙碳酸化制备硫脲的中间产物硫氢化钙的工艺。用正交设计法找出了硫化钙碳酸化制备硫氢化钙的最优工艺参数:反应时间1.5h、温度30℃、气流速度80个气泡/min。在此条件下,硫的转化率达88.90%,并用制备的硫氢化钙合成了纯度为93.21%的硫脲。表明了以磷石膏为原料制备硫氢化钙生产硫脲是可行的。     

废气硫化氢制硫脲

生产农药马拉松时产生的硫化氢废气,污染环境,危害人民身体健康。遵照伟大领袖毛主席关于“我们的责任,是向人民负责。”、“综合利用大有文章可做”的教导。我们互相协作,用石灰乳代替液碱,制成硫氢化钙,再用硫氢化钙与石灰氮反应,生产硫脲,为生产硫脲和硫化氢废气的综合利用闯出了一条新路。几年来,利用废气硫化氢,已生产了硫脲200多吨,现已部分供应出口,远销国外市场。已回收的资金为设备投资的80多倍。     

硫脲生产过程中副产物—双氰胺的测定

1 前言 硫脲,化学名称为硫代尿素,分子式为(NH_2)_2CS,结构式为C=S,分子量为76.12。主要用作制药、印染、选矿等行业。硫脲生产过程中所采用的主要原料为硫化氢气体及氰氨化钙(俗名:石灰氮。在生产过程中,会发生许多副反应,其中主要副反应产物为双氰胺,双氰胺量的多少,直接影     

尿素-氰氨化钙法生产硫脲产业化试验

文章介绍了用生产装置进行"尿素-氰氨化钙法生产硫脲"的研究试验。试验结果为,投入约1.9 t左右的尿素,即可产出1 t质量合格的硫脲。     

用硫化氢尾气生产硫脲的工业方法述评

综述了制备硫脲的各种方法。重点介绍了工业生产硫脲的两种方法，石灰石-石灰氨法和尿素-氰氨化钙法，并对它们的工艺过程和优缺点进行了较详细的比较。     

硫脲合成新工艺

改石灰乳负压吸收硫化氢再与石灰氮反应生产硫脲的传统方法为直接用石灰氮悬浮液负压吸收硫化氢再与石灰氮反应。改进的新工艺是在８０００Ｌ反应釜中加６０００Ｌ循环液（第１次为水）,再加５００ｋｇ石灰氮,负压导入硫化氢,保持温度８０℃,硫化氢饱和,温度不再上升即为终点（此为第１阶段）。第２次加石灰氮１０００ｋｇ（由测定液中硫氢化钙含量来决定投入量）,保持温度８０℃,反应４ｈ后,过滤、洗涤、弃去残渣,控温７０℃左右、冷却、结晶,冷至２０℃,过滤、洗涤、烘干即为产品,收率８２５%。滤液、洗涤液合并为循环液,下次套用。硫氢化…     

硫氢化钙的自动电位滴定分析法

<正> 硫氧化钙[Ca(HS)_2]是合成硫脲的主要原料之一,由硫化氢与石灰乳反应制得。硫氢化钙的分析,多数厂家采用碘量法,也有用中和法或 EDTA 容量法的。但碘量法受样中可能存在的硫代硫酸盐、亚硫酸盐的干扰;中和法不但 Ca(OH)_2 的存在有干扰,且滴定过程中放出的 H_2 S 污染环境,而EDTA 容量法定钙受样品中 Ca(OH)_2 和其它钙离子的干扰。     

低铁硫氢化钠生产工艺研究

采用工业品硫化钡（60％）配制成150g/L的溶液，吸收硫化氢气体制备成175g/L的硫氢化钡溶液。     

以炼厂硫化氢为原料生产硫脲的试验及可能性研究

试验采用国内硫脲的主流生产工艺,即以硫化氢气体为原料石灰氮一步法生产硫脲,制定了试验方法和步骤。试验共做了5次,在前4次试验的基础上逐步改进和完善,终于在第5次试验产出合格的工业硫脲产品,同时证明了以炼厂硫化氢气体为原料可以生产出合格的硫脲产品。     

三聚氰胺工艺降低尿素单耗的调控对策

对气相淬冷法三聚氰胺工艺降低尿素单耗提出可行性的调控对策,以期降低生产成本,完善工艺设计,优化工艺操作,稳定装置生产.     

川化大化肥装置技术改造思路和方案

将大化肥装置技术改造与三聚氰胺扩建联合考虑，形成合成氨增产20％、尿素增产50％的改造方案，尿素改造采用改良ACES工艺，达到投资效益最佳的目的。     

Prebiotic Origin of Pre-RNA Building Blocks in a Urea “Warm Little Pond” Scenario

Urea appears to be a key intermediate of important prebiotic synthetic pathways. Concentrated pools of urea likely existed on the surface of the early Earth, as urea is synthesized in significant quantities from hydrogen cyanide or cyanamide (widely accepted prebiotic molecules), it has extremely high water solubility, and it can concentrate to form eutectics from aqueous solutions. We propose a model for the origin of a variety of canonical and non-canonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs.The dual nucleophilic-electrophilic character of urea makes it an ideal precursor for the formation of nitrogenous heterocycles. We propose a model for the origin of a variety of canonical and noncanonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs. These reactions involve urea condensation with other prebiotic molecules (e. g., malonic acid) that could be driven by environmental cycles (e. g., freezing/thawing, drying/wetting). The resulting heterocycle assemblies are compatible with the formation of nucleosides and, possibly, the chemical evolution of molecular precursors to RNA. We show that urea eutectics at moderate temperature represent a robust prebiotic source of nitrogenous heterocycles. The simplicity of these pathways, and their independence from specific or rare geological events, support the idea of urea being of fundamental importance to the prebiotic chemistry that gave rise to life on Earth.     

A continuous process for recovery of sulfur from natural gas containing low concentrations of hydrogen sulfide

A continuous catalytic process was developed to remove hydrogen sulfide from a natural gas stream using activated carbon as catalyst. The concentration range of hydrogen sulfide in the gas stream studied was 300–3000 ppmv (0.0126–0.126 moles/m³). Virtually 100 percent conversion of hydrogen sulfide was achieved by the combination of various parameters. The “field gas” employed in this study exhibited cracking of some heavier hydrocarbons and made the product sulfur slightly brown. These hydrocarbons should therefore be separated from the gas stream prior to the oxidation reaction. No carbon monoxide or carbon dioxide was produced during the oxidation of hydrogen sulfide. It is concluded that the process described herein has the potential for the removal of hydrogen sulfide as sulfur from a sour natural gas stream on a continuous basis and could therefore eliminate an environmental problem which now exists.     

我国硫脲生产现状及市场分析

介绍了我国硫脲的生产现状,工业上大多数厂家采用硫化氢和石灰氮法生产, 2003年全国硫脲产量为 6万t;硫脲在医药、造纸、纺织、橡胶及印染等行业具有广泛的应用。综述了国内外硫脲的生产和市场现状,目前世界硫脲的总产能为 8万t/a,并预测今后几年硫脲的消费将保持增长的趋势。建议我国应发挥原料和价格优势,大力发展硫脲及其下游产品的开发工作。     

Transformation of calcium cyanamide and its inhibitory effect on urea nitrification in some tropical soils

Transformation of calcium cyanamide and its inhibitory effect on urea nitrification was studied in some tropical soils. Three soils, from Onne, Mokwa and Samaru, representing different agro-climatological zones of Nigeria were incubated with calcium cyanamide, urea or a mixture of both for eight weeks at 30 °C and at field capacity moisture content. The recovery of inorganic N (NH ₄ ⁺ plus NO ₂ ^- plus NO ₃ ^- )from calcium cyanamide varied from 64% to 87% in different soils. Most of the inorganic N accumulated was in NH ₄ ⁺ form. Nitrification of the accumulated NH ₄ ⁺ in all the soils was slow.Urea (75 mg N kg^–1 soil) was completely nitrified within a week in the Samaru and Mokwa soils whereas in the Onne soil the rate of nitrification was slow. Addition of CaCN₂ at the rate of 10 mg N kg^–1 soil generally delayed ammonification of urea and nitrification was severely inhibited in all the soils. Addition of CaCN₂ at the rate of 20 mg N kg^–1 soil further reduced the ammonification of urea and completely inhibited the nitrification. High recovery of inorganic N from calcium cyanamide and its effective reduction of nitrification of urea make it suitable source of N for plants in the tropics, provided it is managed to avoid phyto-toxicity.     

通过测定硫化副产物硫化锌来检验硫化橡胶的硫化程度

介绍了用硫化副产物硫化锌来检验硫化橡胶硫化程度的方法。丙酮抽提过的硫化橡胶置于醋酸、盐酸和水的混合溶液中浸煮，使硫化胶中的硫化锌分解，产生的硫化氢气体用醋酸镉的缓冲溶液吸收，用碘量法测定其中的含硫量。结果表明，硫化胶中的硫化锌含量与硫化时间有关，并根据最佳硫化条件时的Ｓ（ＺｎＳ）含量，对所研究的硫化橡胶的硫化程度进行了检验。     

Carbodiimide catalysis in cross-linking of cotton cellulose with 1,2,3,4-butanetetracarboxylic acid

This study examined carbodiimde catalysis (cyanamide, dicyandiamide, disodium cyanamide) in the cross-linking of cotton cellulose with 1,2,3,4-butanetetracarboxylic acid (BTCA). Considerable improvement in the smooth drying appearance of the treated cotton substantiated the fact that cellulose cross-linking has been achieved by BTCA in the presence of carbodiimide. Bath pH was a very important factor in determining the performance properties of the treated cotton. Two possible reaction mechanisms were proposed: direct esterification and anhydride intermediate formation. Both pathways involved the formation of urea. Semiquantitative analyses of the spectra obtained by Fourier transform infrared spectroscopy revealed that the cyanamide was somewhat less effective than were dicyandiamide and sodium hypophosphite in esterification efficiency. © 1995 John Wiley & Sons, Inc.     

催化氧化法处理含硫废水的研究

硫化物是煤化工废水常见的污染物之～,现有多种处理方法,其中空气氧化法以成本低、效果较好而备受重视,但存在反应速率慢、硫化氢逸出等缺点。从3种非均相催化剂中选出效果最佳的PT-OC01催化剂,以硫化物的去除率和硫化氢逸出率为指标,设计正交实验,找出最佳的工艺条件。实验结果表明,硫化物去除率可达87．3％,硫化氢逸出率仅为0．25％。