- 作者: SHEH-SHON CHOU
- 作者服務機構: Dept. of Mining Metallurgy and Materials Science Cheng-Kung University
- 中文摘要: When an electric field is applied to a liquid metal or alloy, in addition to thetransport of eloctrons, a relatively small transport of the metal ions also occurs.This process of mass transport of metal ions is refereed as eIectrotransport orelectrodiffusion. This project is to study the application of the electrotransportphenemenon as a means of purifying metals in purification of Ultra high-puritymetallic cadmium from its impure metal. At first, theoretical determination of thepossibility of purification is presented. Dr. Verhoeven's formula is applied todetermine the ratio of relative mean concentration (Cm(l)) of impurity component co solute in a dilute liquid metallic solution. This value of ratio may be used as astandard in understanding the puification work. In this work, we are going to find the proper condition of minimum value of ratio (Cm(yt)) by mathematical co calculation. This ratio value should be below 10-6,so that the experimental workis effective for purifying. In this work,a detailed description for solving theproblem and how to apply the computer in calculation are presenled. A theoretcalare also described. According to the calculated data, the theoretical proper conditions are in therange of the electric field intensity 0.1~0.2 Volt/cm, Temperature 350oC~400oC,Time 24~48 Hr. Tube length 10 cm. On the experimental work, a self-design ofpurification cell is based on the modification of the capillary reservior technique,Using the high temperature resistance glass tube of Taiwan Glass Works, andimpure Cadmium metal as experimental material. In this work, a detailed descrip-tion on the experimental work, process and equipment are listed. A discussion onthe analysis of experimental result is also described. According to the experimen-tal data showing, using the pure Aluminum wire as the electrode in connecting thepurification cell show a good effect in this experiment. From the experimental datashowing, on the purifying condition of electric field intensity 0.15~0.2 Volt/cm,current demtity 15 Amp/cm2~16 Amp/cm2. Temperature range 350~400oC. time15 Hr.~24 Hr, The removing of small impurity of Co, Zn, Hg, Sn from Cd solventliquid metal are excellent. A spectral analysis from the Fisher-Todd spectralequipment showing, the concentration of these impurity can be removed from therange of 0.1%~0.01% each to a value of less than 0.001% approximately. A longtime of more than 24 Hr. is necessary for removing the Fe and Cu impurities fromCd melt. In general conclusion, under the condition of our country, this electrodiffusiunmethod in the preparation of small quantity of high purity cadmium material usedin research work is available, and a continuous study is necessary too.
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