zone refining is based on

horizontal-, vertical-, floating- as well as continuous zone refining (as presented in Figure 4). Each zone carries a fraction of the impurities to the end of the solid charge, thereby… When high purity is required, such as in semiconductor industry, the impure end of the boule is cut off, and the refining is repeated. (d) Zone refining. are solved by group of students and teacher of Class 12, which is also the largest student community of Class 12. Its first commercial use was in germanium, refined to one atom of impurity per ten billion,[2] but the process can be extended to virtually any solute-solvent system having an appreciable concentration difference between solid and liquid phases at equilibrium. In zone-refining method the molten zone contains more impurity than the original metal. The refining efficiency of each succes- Can you explain this answer? Another method is to pass an electric current directly through the ingot while it is in a magnetic field, with the resulting magnetomotive force carefully set to be just equal to the weight in order to hold the liquid suspended. Zone refining refers to the method of purifying a crystal wherein a thin region of the crystal undergoes melting. In this, the zone should be moving as slowly as possible to get highly pure metal. can purify by this process. To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. The Questions and Answers of On what principle is the method of zone refining of metals based? By melting a portion of such an ingot and slowly refreezing it, solutes in the molten region become distributed to form the desired n-p and p-n junctions. ��#���Dܙ �fzh�Q0� `�D�*������.2[��ڶٴ4)�1>Ͳ�|n�͖��ưˮ�^�F�@{��6 -Q�Φ��ete�^�طY�.L�NW.��@Q� �< Zone refining is a very useful method to get metals with very high purity such as silicon and germanium. For example: extremely pure silicon, germanium, boron, gallium and indium are refined by this method. See more. This study presents an efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment, separation, and purification of alkaloids and organic acids from natural products. Pfann [4] suggested to use a longer zone in the first part of the ingot, followed by a shorter zone … Zone Refining. Zone refining is the most important of the zone-melting techniques. With little difficulty several molten zotles can be passeed through an ingot, one behind the other, with each zone-pass comprising a … Zone refining is based on the fact that under conditions of equilibrium between the liquid and solid phases, the solubility of the impurities is different in the two phases. Problem 2 (2 Points) Zone refining of metals is a materials processing technology based on the fact that when a molten metal crystallizes on cooling, impurities are automatically expelled since they do not form part of the pure crystal. This technique is also used for the preparation of silicon for use in computer chips. 2. Impurities are incorporated in the melting liquid and freezing solid. are solved by group of students and teacher of Class 12, which is also the largest student community of Class 12. (i) impurities of low boiling metals can be separated by distillation. Because of this when a molten metal crystallizes on cooling, impurities are automatically excluded as they do not form part of the pure crystal. 3 0 obj Zone refining was inv… to the geometry or the way of charging, they could be categorized in four types, X. X. Zhang et al. If the answer is not available please wait for a while and a community member will probably answer this soon. As the heater moves, the molten zone … 2 0 obj : The liquid zones are formed by heating (and by cooling the adjacent solids). This method is based on the principle that the impurities are more soluble in the molten form as compared to the solid state of the metal. (Image courtesy: News coverage by Egypt Today provided by Bechtel website) Egyptian Petrochemicals Holding Company (ECHEM) signed a cooperation agreement with American company, Bechtel Group, with an investment of $6.7bn, the Ministry of … <> The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it as it moves through the ingot. The method of zone refining of metals is based on the principle of : A Greater mobility of the pure metal than that of the impurity. (ii) impurities are more soluble in molten metal than in solid metal. Zone melting (or zone refining or floating-zone process or travelling melting zone) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Another separation procedure based on liquid-solid equilibria is zone melting, which has found its greatest use in the purification of metals. Silica reacts with iron oxide and forms iron silicate, which is removed as slag. C Greater noble character of the solid metal than that of the impurity. (ii) Ores of copper contain iron oxide as an impurity. Assertion : Zone refining is based on the solubilities of impurities in the molten state than in the solid state of a metal. In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. Question 20.
Statement : Pure metal oxide is obtained in zone refining. Indirect-heating floating zone methods use an induction-heated tungsten ring to heat the ingot radiatively, and are useful when the ingot is of a high-resistivity semiconductor on which classical induction heating is ineffective. Silicon , boron gallium , indium etc. B Higher melting point of the impurity than that of the pure metal. … Definition of zone refining : a technique for the purification of a crystalline material and especially a metal in which a molten region travels through the material to be refined, picks up impurities at its advancing edge, and then allows the purified part to recrystallize at its opposite edge — called also zone melting {\displaystyle dx} This method is based on various solubility of impurities in firm and liquid phases. up In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. �W�^� Therefore, at the solid/liquid boundary, the impurity atoms will diffuse to the liquid region. Zone refining is based on the principle that _____. DOI: 10.1016/j.seppur.2019.116089. This method is used for metals which are required in very high purity. 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