从乏燃料中分离锕系元素的研究进展

总结了目前从乏燃料中提取放射性锕系元素的方法。锕系元素的分离减少了乏燃料相关的危害,例如其放射性毒性、体积和其放射性恢复到自然发生水平所需的时间量,并简要讨论了从环境水体系中分离锕系元素的问题。通常在乏燃料中发现的锕系元素包括铀、钚和次锕系元素(Am、Np和Cm),其中铀和钚的分离方法已经相当成熟,然而乏燃料中存在的次锕系元素与镧系裂变产物的分离还处于不成熟的阶段,需要进一步的研究探索。最后介绍选择性去除锕系元素的一些固体吸附材料。     

溶液中钴与镍的深度分离研究进展

通过回顾国内外溶液中钴与镍分离技术的研究进展和发展现状,分析和比较了主要的分离技术的特点和优缺点,展望未来的研究趋势。分析表明:溶剂萃取是钴镍分离的主要工艺方法,但存在有机溶剂耗量大,会对环境造成污染的问题;螯合树脂分离溶液中钴镍的方法效率高、发展较快,但存在树脂机械强度差的缺陷,研发高强度的耐磨损螯合树脂及类似的螯合吸附材料是离子交换技术分离钴镍的研究方向。萃淋树脂交换、非有机溶剂萃取技术等集成方法,是克服缺点、充分利用各方面的优点组成的新工艺,可实现钴镍高效分离、环境友好,是今后的研究趋势。     

萃取锕系元素的新型酰胺类萃取剂研究进展

酰胺类萃取剂作为锕系元素的一种优良新型萃取剂，具有易合成、耐辐射、不易水解、辐射产物易洗涤、不影响萃取过程和能完全燃尽等优点，被认为是能取代TBP应用于核工业的最有前途的萃取剂之一。近十几年来，人们对此类萃取剂研究较多。本文将对N，N-双取代酰胺类、N，N，N′，N′-四取代双酰胺类、环状酰胺类等几种萃取剂的研究进展进行详细讨论。     

溶剂萃取精馏分离烷烃与烯烃研究进展

PROGRESSOFSEPARATIONOFALKANESANDALKENESBYSOLVENTEXTRACTIVEDISTILLATIONWangWenhua1前言沸点相近的烷烃与烯烃用普通精馏较难分离,多采用溶剂苹取精馏。近年来由于烯烃用途的不断开发成功,促使溶剂苹取精馏技术发展非常迅速,本文对近年来萃取精馆技术的研究和进展加以论述。2溶剂的选择溶剂车取精馆是在精馏塔中加入能提高待分离组分相对挥发度的一种或几种溶剂,使沸点相近的组分得以分离。溶剂革取精馏所选用的溶剂是分离效果好坏的关键因素,烯烃苹取精馏所用溶剂应用与烃类不相互反应、不形成共沸…     

从二甲基萘异构体中分离2,6-二甲基萘的研究进展

2,6－二甲基萘是制备高性能聚酯－聚对萘二甲酸乙二醇酯最理想的原料,如何低成本地获得2,6－二甲基萘已成为一项重要的课题。本文介绍了从二甲基萘异构体中分离2,6－二甲基萘的方法,即超临界萃取法、压力结晶法、吸附分离法及冷冻结晶法等,并论述了它们的优缺点及日后的发展方向。     

碱土金属溶剂萃取分离的新进展

本文就碱土金属离子萃取分离的进展情况,按萃取剂的分类进行了综述。     

从浓缩盐湖卤水中萃取分离锂的实验研究

采用溶剂萃取法,对中国青海某盐湖浓缩后的高镁锂比老卤中的锂进行分离提取,系统考察了萃取剂浓度、萃取相比、卤水酸度等因素对锂萃取率的影响。对富锂有机相进行反萃取,考察了反萃取相比、反萃剂盐酸浓度等条件对锂负载有机相反萃取的影响。萃取工艺对从高镁锂比盐湖卤水中分离锂具有较好的应用前景。     

硫酸法二氧化钛生产中萃取分离钛、铁的研究进展

介绍了溶剂萃取技术在萃取分离硫酸介质中的钛、铁方面的应用.针对该技术在硫酸法二氧化钛生产中的应用,指出了今后的研究重点与方向.     

从铜熔炼烟灰浸出液中萃取分离铜的试验研究

以铜熔炼烟灰浸出液为研究对象,采用N902萃取剂从中分离回收铜,并将铜元素进行富集。研究了萃取剂浓度、相比(O/A)、溶液pH值、振荡时间对铜萃取分离的影响,以及反萃剂浓度、相比、振荡时间对铜反萃率的影响。试验结果表明,在萃取剂质量分数12%、相比(O)/(A)=1∶2、溶液pH值为2.0、振荡时间6 min的萃取条件下,通过两级逆流萃取,铜、锌、铁的萃取率分别为98.26%、1.29%、2.28%;铜与铁、锌的分离系数分别达到4346和2425,实现了铜与铁、锌的有效分离。在选定反萃剂硫酸铜浓度为2.5 mol/L、相比(O)/(A)=2∶1、振荡时间6 min的条件下,通过两级逆流反萃,铜的反萃率为94.68%,反萃后铜质量浓度达到7.04 g/L,相较于浸出液中铜离子质量浓度提高了约3.72倍,实现了铜离子的富集,得到的硫酸铜溶液可用于电积铜生产。     

Real-time monitoring of actinides in chemical nuclear fuel reprocessing plants

Spent nuclear fuel chemical reprocessing plants process several 10³ kg of spent nuclear fuel, especially Pu isotopes, which present significant potential for terrorism (Note: ∼8 kg Pu constitutes a threat level quantity). This requires detecting actinides in transit, but also, to ensure they are not diverted. Present-day sensors disallow real-time monitoring leading to significantly non-optimal operations.     

Bioleaching of spent refinery catalysts: A review

Large quantities of solid catalysts are routinely used in many chemical industries especially in petroleum refining and petrochemical industries. Solid catalysts contain metals, metal oxides or sulfides, and require replacement after two or three years of operation. Therefore, large quantities of spent catalysts are generated as solid wastes every year. Because of their hazardous nature and toxic chemical products, there are stringent environmental regulations for discarded spent catalysts. The recovery of metals from these catalysts is also an important economic aspect as most of these catalysts are supported, usually on alumina/silica with varying percent of metal. Bio-hydrometallurgical approaches are more economical and environmentally friendly than physicochemical metal-extraction processes. In this paper, the information available on the bioleaching fundamentals of spent catalyst wastes, as well as a focus on recent developments, is reviewed in detail.     

Nitric acid purification from admixtures of volatile acids by fractionation during waste evaporation at a spent nuclear fuel reprocessing company

We present the results of the computer simulation of a method for better purification of nitric acid from HF and CH₃COOH admixtures by creating a stripping section in the fractionation column with HNO₃ scrubbing and by the feeding of a parasitic water flow to the bottom section. The production column in the evaporator section of the RT-1 plant at the PA ??Mayak?? was upgraded using the calculation results and test trials on real process high-level waste were performed, which made it possible to improve the purification of regenerated 12 mol/L HNO₃ from HF and simultaneously from HCl by a factor of 3?C5. The specification figures for three flowsheet of nitric acid regeneration that were used at different times since 1979 for commercial purification from halogens and radioactive contaminants were compared.     

Ethanol and diesel fuel from plant raw materials: A review

Data on various methods for the production of ethanol (bioethanol) and diesel fuel (biodiesel) from plant biomass and on the properties of raw materials in use are presented. Main trends in the development of processes for plant biomass conversion into bioethanol and biodiesel are considered.     

Integrated fuel processors for fuel cell application: A review

This report documents the key technological progress made over last two decades in the field of development of integrated fuel processor for hydrogen generation. Studies on process optimization based on numerical simulation/calculation, mass and energy management, parametric adjustment have been reported. A number of these studies discuss the application of reforming process assisted by other technologies such as pressure swing adsorption and membrane separation to enhance the hydrogen productivity and/or purity. However, for such systems the extent of integration among and between components remains limited. Accordingly, the net efficiency is compromised due to the mass/heat transfer rate and reaction dynamics either in the individual units or the complete system. Process intensification technologies such as engineered catalysts, on-site heat production/removal and product purification can not only allow precise control of reaction and heat/mass transfer rates, but also help optimize the operation conditions, and, consequently, improve overall efficiency and mitigate the requirement for materials and capital investment. It seems that micro-scale technologies, possessing the typical characteristics of process intensification technologies, have potential for making the integrated fuel processor into practice.     

Sorptional properties of fuel shale and spent shale

The sorptional properties of fuel shales and spent shales in removing organic compounds (petroleum and its derivatives) from water are studied. The basic benefit of spent shale as a sorbent is that it is available at no expense as the processing waste of fuel shale. After sorption, the fuel shale or spent shale saturated with petroleum or its derivatives may expediently be used as a fuel, on account of their high calorific value.     

微生物燃料电池阴极功能的研究进展

从微生物燃料电池的阴极功能角度出发,对阴极电子接受体的作用及其发展进行了综述。论述了传统的阴极电子接受体为氧气、铁氰化钾、高锰酸盐及碘的应用,总结了后期发展起来的电子接受体为质子、金属离子、二氧化碳、硝基化合物、硝酸盐等的进展状况。最后对微生物燃料电池功能的拓展进行了展望,微生物燃料电池将在氢能、重金属回收、二氧化碳减排捕获以及脱氮等领域有潜在的应用前景。     

Corrosive and mechanical resistance of MgO ceramics under metallizing and mild chlorination of spent nuclear fuel in molten salts

The present work is aimed at the study of the unirradiated and irradiated MgO ceramics corrosion and mechanical properties in the molten LiCl at 650–750 °C with addition of UCl₃ and Li₂O(LiCl + nLi₂O and LiCl + mUCl₃ molten salts with n = 1.0 and 2.0 mol. % and m = 0.25, 0.5 and 1.0 mol. %). MgO ceramics is suggested to be used as one of materials for pyrochemical technology for recycling of spent nuclear fuel.The gravimetric method with the exposure time during 100 h was the primary method of investigation. The investigation of surface and bulk corrosion of MgO samples by scanning electron microscopy (SEM) and X-ray spectroscopy (MRSA) was performed using scanning electron microscope equipped with a x-Act 6 energy-dispersive analytic system for X-rays characteristic (XRС). Determination of corrosion losses and average corrosion rates of MgO samples was based on the assumption that the ejection of the radionuclides ⁹⁵Zr, ¹⁷⁵Hf and ¹⁸¹Hf from the MgO samples.Incorporation of Li₂O and UCl₃ in molten LiCl result in increase in the rate of MgO ceramic corrosion both at 650 °C and 750 °C and acts on MgO compressive strength (σ_cs) and on the elemental composition of MgO surface layers. Besides the increasing of UCl₃ concentration led to the bulk corrosion of MgO sample grains.Short-term mechanical tests demonstrated the transition of MgO sample destruction pattern depending on the concentration of Li₂O and UCl₃ additions in LiCl melt.Doping of molten LiCl by 0.5 mol. % of UCl₃ at 650 °C and by 0.25 mol. % of UCl₃ at 750 °C had no influence on the ultimate compression strength of irradiated and unirradiated MgO samples. Increased UCl₃ concentration totaling 0.5 mol. % in the LiCl melts at 750 °C reduced the ultimate compression strength of irradiated MgO ceramic samples by ~15%.     

Foam fractionation of spent sulphite liquor: Part I: Separation of surfactants

The surface activity of spent sulphite liquor (SSL) and the separation of surface active components by foam fractionation were studied. The maximum activity (lowest surface tension) of SSL was observed at a high pH. The surface tension was found to be 42 mN/m and 38 mN/m at acidic and basic pH values, respectively, and also a maximum foaminess (Σ) of 7 min was observed at pH 10. Foam fractionation reduced the surfactant concentration by 90% at an optimum pH of 10. The surfactants were concentrated in the collapsed foam as shown by the fact that the critical micelle concentrations of the unfractionated SSL and foam were 70% (v/v) and 10% (v/v), respectively. The removed surfactants were concentrated in 20% of the original liquid volume.