Synthesis of powder uranium tetrafluoride from depleted uranium hexafluoride in hydrogen fluoride flame

The mechanism of uranium tetrafluoride formation during the reduction of depleted uranium hexafluoride in hydrogen fluoride flame has been studied. Based on the performed studies, it has been established that powder uranium tetrafluoride with characteristics that enable it to be used for both long-term storage (minimum specific surface area, 0.6 ± 0.1 m²/g; untapped density, 2.7 g/cm³) and metallic uranium production (maximum specific surface area, 1.45 m²/g) can be obtained by adjusting the operational regime of a flame reactor.     

利用等离子反应器从SiF_4与CH_4制备HF和SiC的探索研究

研究了一个新型反应,即SiF_4气体与CH_4气体反应生成无水HF气体和SiC固体。该反应在最大能量为20eV的等离子反应器的固定床中进行,反应一段时间后,收集反应器壁上固体,通过分析固体中的碳含量来判断四氟化硅和甲烷的反应情况。结果表明:四氟化硅和甲烷可以发生反应,但是速度十分缓慢。     

双氦离子化气相色谱仪分析四氟化硅气体中微量杂质

介绍了一种利用双通道氦离子化气相色谱仪(PDHID),分析四氟化硅中微量硅烷、磷烷、氟代烷、C2～C3碳氢化合物以及常见气体杂质的方法.由于四氟化硅具有很强的腐蚀性,在对其进行分析时,利用阀切割系统将大量的四氟化硅主要成分切割,及时地将四氟化硅反吹出去,使其不进入检测器系统.经过将四氟化硅气体进样检测验证,该方法能够有效测定四氟化硅气体中多种微量杂质.     

Modelling of a moving bed furnace for the production of uranium tetrafluoride Part 1: formulation of the model

Reduction, followed by hydrofluorination of uranium trioxide UO₃ to produce uranium tetrafluoride UF₄ is one of the stages of the French nuclear fuel making route. This dual operation is carried out in a specific reactor known as a moving bed furnace, consisting of a series of steel cylinders that form an L. In this first part of a two-part paper, the mathematical modelling of the furnace is presented in detail. The model describes solid and gas flow, heat transfer by convection, conduction and radiation in the moving bed and in the walls of the furnace, and chemical reactions. In the vertical part of the reactor, mass, momentum and energy balances are solved using the finite volume method. The horizontal part is modelled by a cascade of stirred gas and solid reactors. The assumptions and equations of the model, as well as the boundary conditions and numerical solution techniques are detailed. An example of calculated results is presented and found to agree satisfactorily with available measurements. Application of the model is discussed in Part 2.     

四氯化硅和四氟化硅的研究比较

SiCl4主要是作为改良西门子法生产多晶硅的副产物得到,SiF4主要是作为磷肥工业的副产物氟硅酸分解得到,但是二者纯度都不能满足生产多晶硅的要求,需进行分离纯化得到高纯物质。本文针对SiCl4和SiF4的物化性质、合成工艺、精制方法、应用前景等方面做了探讨和比较,指出SiF4比SiCl4更具应用前景。     

Interaction of Yttria with Uranium Fluoride Gases (UFn, n= 4, 6) at High Temperatures

The corrosion mechanism and microstructural characteristics of yttria (Y₂O₃) exposed to uranium hexafluoride (UF₄) and uranium tetrafluoride gases at temperatures above 900°C were investigated. Processed yttria samples were exposed for times ranging from 5 to 40 min. A weight increase was observed after each test exposure. An outer corrosion scale composed of UO₂ and YF₃, and an inner corrosion layer of YF₃, were observed following the UF₆ reaction at nearly 1200 K. During the UF₄ exposure, an outer layer containing a liquid mixture of fluoride, oxygen, yttrium, uranium compounds, a secondary reaction layer of UO₂ followed by an inner layer composed of a solution of Y₂O₃ and YF₃, possibly in the form of YOF inner layer, were observed. It was found that the corrosion process is controlled by the diffusion which is evidenced by the parabolic growth rate of the secondary layer. After completion of the solidification process, the formation of a eutectic region and dendrites were observed throughout the outer scale. In general, at temperatures above 1173 K, high corrosion rates were observed, and yttria did not appear to be a viable containment material for UF₄ and UF₆.     

四氟化硫的制备和提纯方法

评述了四氟化硫的制备和提纯方法。四氟化硫的制备方法按氟来源可分为五种制备方法：氟气氟化法、氟化氢氟代法、有机碱氢氟酸盐氟代法、金属氟化盐氟代法和非金属氟化物氟化法。四氟化硫的提纯方法可分为汞结合法、吸收法和高温老化法。     

Modelling of a moving bed furnace for the production of uranium tetrafluoride. Part 2: Application of the model

The French nuclear fuel making route uses, prior to enrichment, uranium tetrafluoride UF₄ obtained from the reduction, followed by hydrofluorination of uranium trioxide UO₃. These two steps are carried out in a specific reactor known as a moving bed furnace. We developed a steady-state numerical model of the moving bed furnace, described in Part 1. In the Part 2, calculation results for a reference set of operating parameters of the furnace are presented in term of temperature, reaction rates, solid and gas compositions. Results analysis enlightens the detail of the furnace behaviour in its different zones. Unknown features have been revealed, such as thermodynamic limitation of the hydrofluorination reaction in the hot core of the moving bed. A sensibility study of various operating parameters shows how some can influence the UF₄ quality and underlines the strong coupling between the different zones of the furnace. Finally, the model is applied to define an optimal temperature progression in the furnace and suggests geometrical modifications. Besides, the validity of using the law of additive reaction times for calculating the reaction rates in such a reactor model has been checked for the first time against a numerical grain model.     

四氟化碳的合成与开发(续)

(接第3期第17页 )2.2.1 吸附法意大利一家公司的专利介绍一种用特制的合金脱除全氟烷中水分和氧的方法[36]。该合金组成质量分数为Zr47%~70%,V24%~45%,Fe5%~10%,将其加工成直径<125靘的粒子,在真空或惰性气体保护下于300℃处理全氟烷,可有效去除水分和氧。杜邦公司的专利介绍一种使含空气和CO的全氟烷与MnO2和CuO混合粒子接触,在高温下使CO氧化为CO2;再用蛭石承载的碱石灰或NaOH粒子吸收CO2,最后用4A分子筛干燥提纯全氟烷的工艺[37]。催化剂粒子通常为8~24目,质量分数为MnO267%~86%、CuO14%~33%,反应温度200℃。该方法可连续进行…     

Photoluminescence and Absorption of a Zirconium Fluoride Glass and ZrF4

The glass containing reduced zirconium exhibits a photoemission band at 480 nm and an excitation band from 230 to 370 nm. Reduced zirconium tetrafluoride has broad absorption at 400 nm. Reduction of zirconium tetrafluoride occurs through fluorine or oxygen impurity elimination. When fluorine ion deficiency occurs, emission and excitation bands appear at 440 and 350 nm, respectively. When oxygen deficiency occurs, emission and excitation bands appear at 480 and 300 nm, respectively.     

Design of a moving bed reactor for the production of uranium tetrafluoride based on mathematical modeling

A new model has been developed to analyze the performance of a moving bed reactor producing uranium tetrafluoride. The model includes the solid and gas flow rates, heat transfer by convection, conduction and radiation between gas and solid streams and by the external surrounding. A kinetics model has been also developed for the gas–solid reactions on the basis of the grain model in which, the different resistances are taken into account to determine the overall reaction rates. This study provides an initial and theoretical basis for optimum design of the moving bed on the basis of the kinetics models. The optimum design is carried out from the viewpoint of required length of the reactor and the maximum conversion. According to the primary expectations which are provided by the kinetics models, the feed temperature seems not to have any effective influence on the reactor performance. On the other hand, it is predicted that the inlet gas flow rate contributes an important role. The investigations show that although the kinetics models are rather useful in primary estimations, the strong interdependence between different zones of the reactor may prevent general expressions.     

SPC技术在高纯四氟化硅生产中的应用

本文以高纯SiF4生产过程中精馏后的HF含量作为质量管理的对象,论述SPC技术在SiF4生产质量控制中的初步应用。     

氟气中氮气和四氟化碳的快速分析

电解法制得的氟气含有氮气、氟化氢和四氟化碳等杂质。利用氯化钠与氟气反应生成氯气,经NaOH溶液吸收氯气后用普通的气相色谱测定其中四氟化碳含量,操作简单、快速。     

四氟化碳中痕量气体杂质的气相色谱分析

采用配有放电离子化检测器的气相色谱仪分析高纯四氟化碳中痕量气体杂质。研究了分析四氟化碳中氧气、氮气、一氧化碳、二氧化碳和六氟化硫等气体杂质的操作参数,确定了高纯四氟化碳中痕量气体杂质的分析方法。     

四氟化硅的工艺研发及进展状况

四氟化硅是电子工业中的一种重要原料,随着多晶硅等行业迅猛发展需求量逐渐增大。详细介绍了四氟化硅的应用及市场情况,并对氟气合成法、氟硅酸盐热解法、硫酸法、氢氟酸直接反应法这4种主要生产方法进行详细论述,讨论了各工艺方法的生产原理、工艺简述、研究状况并对工艺的优缺点进行了评价。就目前市场形势分析,国内四氟化硅需开发高端产品,以适应市场需求和参与国际竞争。     

氟硅酸钠热解制备四氟化硅气体影响因素研究

磷肥副产物氟硅酸钠热解可制备四氟化硅气体,该方法无废弃物产生,生产成本较低,具有广阔的发展前景。对影响氟硅酸钠热解的各种因素进行了一系列静态实验研究,实验发现,氟硅酸钠热解的最佳反应温度应保持在中温区（500～700 ℃）,反应压力维持在常压或微负压状态。利用该法生产四氟化硅气体具有气体纯度高和无副产物产生的特点。     

磷矿伴生硅资源制备单质硅的探讨

综述了国内外以四氟化硅、氟硅酸钠（钾）、无定SiO2为硅源制备单质硅的主要方法,并对以无定SiO2为硅源制备单质硅的工艺条件进行了研究与探索。     

α-三氟甲基乙胺合成工艺研究

以L-丙氨酸和四氟化硫为原料,压力下经一步氟化反应制得α-三氟甲基乙胺。实验研究获得的最佳工艺条件为：以100 g L-丙氨酸为原料,n（L-丙氨酸）∶n（四氟化硫）为1∶2,55℃及18-19 kgf/cm^2压力下保温反应12 h,产品收率在55%以上,产品盐酸盐熔点在218.5℃以上。     

普钙含氟废气的回收利用

普钙生产中废气的主要成分是SiF4 。若直接排入大气 ,将严重污染环境。为治理含氟废气 ,沿用已久的方法是处理成Na2 SiF6,本文提出的方法是处理成MgSiF6,同时也有精碘制成。     

四氟化硅·正丙醇络合物裂解过程的模拟计算研究

建立了四氟化硅·正丙醇络合物裂解反应器的数学模型,提出了该模型的求解方法,通过对该模型的模拟计算,分析了裂解反应器操作的影响因素,从设备和操作两方面讨论了优化操作和节省成本的方法,提出了合理的建议。