Developed in 1931 by Dr. Thurman Fleet, the Zone Technique—which was originally called Zone Therapy—is based on the notion that there are six potential zones of the body that, when disturbed by emotional, physical, or chemical stressors, can lead to a variety of diseases and discomforts. Zone refining refers to the method of purifying a crystal wherein a thin region of the crystal undergoes melting. Define Zone Refining. See more. A longer bulk lifetime increases the efficiency of solar cells significantly. Zone refining: It is based on the principle that the impurities are more soluble in molten state than in the solid state of the metal. It is also referred to as zone melting, floating zone process, and traveling melting zone. Based on the data from the literature, the proper solvent systems for the separation of alkaloids by the conventional HSCCC and pH-zone-refining CCC are also summarized. In this, the zone should be moving as slowly as possible to get highly pure metal. (i) Zone refining: This method is based on the principle that impurities are more soluble in the molten state of metal (the melt) than in the solid state. (a) Zone refining of metals: This method is based on the principle that impurities are more soluble in the molten state of the metal (the melt) than in the solid state. research on zone refining of metals including basic theories, variants of zone re-fining technology, parametric optimization, simulation models, and high purity analytical methods, in order to provide an updated reference to the ongoing re-search of zone refining of metals. Zone time definition, standard time as applied at sea, reckoned according to the system of time zones. Optical heaters using high powered halogen or xenon lamps are used extensively in research facilities particularly for the production of insulators, but their use in industry is limited by the relatively low power of the lamps, which limits the size of crystals produced by this method. 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. Silicon , boron gallium , indium etc. Zone system definition, a system for envisioning the values to appear in a black-and-white print and for determining exposure and development, based on a scale of shades ranging from 0 (black) to IX (white). Zone Refining. Separation of solute (impurity) and solvent is gradually increased through subsequent passes of a molten zone travelling along a bar. This method is based on various solubility of impurities in firm and liquid phases. The zone refining method is based on the difference in the solubility of the impurities in the molten and in the solid state of the metal. A circular mobile heater is fixed at one end of a rod of the impure metal. 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. Various zone refining technologies exist based on the same principle. (i) The technique of zone refining is based on the principle that the impurities are more soluble in the molten state of metal than in the solid state. 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. Zone melting is apllying for deep cleaning of p olycrystalline Germanium. The bulk charge carrier lifetime in float-zone silicon is the highest among various manufacturing processes. x (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 impurities concentrate in the melt, and are moved to one end of the ingot. ZONE REFINING Zone refining is a technique used to purify materials, mainly semiconductors by melting a short region (i.e., zone) and causing this liquid zone to travel slowly through a relatively long rod of the solid. 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. It is also referred to as zone melting, floating zone process, and travelling melting zone. 14%. Then a small amount of antimony is placed in the molten zone, which is passed through the pure germanium. 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. ZONE REFINING Zone refining is a technique used to purify materials, mainly semiconductors by melting a short region (i.e., zone) and causing this liquid zone to travel slowly through a relatively long rod of the solid. In zone leveling, the objective is to distribute solute evenly throughout the purified material, which may be sought in the form of a single crystal. 2 0 obj d 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. As the heater is moved, the pure metal crystallizes out and the impurities pass on to the adjacent part of the metal. Answer (i) Zone refining: This method is based on the principle that impurities are more soluble in the molten state of metal (the melt) than in the solid state. Zone refining was invented by John Desmond Bernal[1] and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors. Another related process is zone remelting, in which two solutes are distributed through a pure metal. As the heater moves, the molten zone of the rod also moves along with it. 9%. All practical methods of zone refining are based on the periodic (discontinuous) principle, by which the charging of the ingot is repeated over a specific number of time intervals corresponding to n passages of the molten zone from one end of the ingot to the other. … Zone refining was inv… 4 0 obj In zone refining, impurities are removed by moving molten zone through moving heater and recrystallized pure metal is left behind in solid form. to the geometry or the way of charging, they could be categorized in four types, X. X. Zhang et al. : The liquid zones are formed by heating (and by cooling the adjacent solids). With the proper choice of rate of heating and other variables, the antimony can be spread evenly through the germanium. The molten zone moves along with the heater which is moved forward. Float-zone carrier lifetimes are around 1000 microseconds compared to 20-200 microseconds with Czochralski process, and 1–30 microseconds with cast polycrystalline silicon. Options (a) greater mobility of the pure metal than that of the impurity (b) higher melting point of the impurity than that of the pure metal (c) greater noble character of the solid metal than that of the impurity D Purification of naphthalene by zone refining: Mathematical modelling and optimization by swarm intelligence-based techniques. Zone refining refers to the method of purifying a crystal wherein a thin region of the crystal undergoes melting. With little difficulty several molten zotles can be passeed through an ingot, one behind the other, with each zone-pass comprising a … Answer (i) Zone refining: This method is based on the principle that impurities are more soluble in the molten state of metal (the melt) than in the solid state. )��� T�ϞE�|FQ��./ In zone refining, a solid is refined by passing a number of molten zones through it in one direction. {\displaystyle dx} 3 0 obj Purification process by moving a molten zone along a metal bar, Mathematical expression of impurity concentration, James D. Plummer, Michael D. Deal, and Peter B. Griffin, Silicon VLSI Technology, Prentice Hall, 2000, p. 129, https://en.wikipedia.org/w/index.php?title=Zone_melting&oldid=993869102, Creative Commons Attribution-ShareAlike License, This page was last edited on 12 December 2020, at 22:41. Join The Discussion. The refined metals through zone refining are typically in the form of polycrystalline structures. The principle is that the segregation coefficient k (the ratio of an impurity in the solid phase to that in the liquid phase) is usually less than one. If the answer is not available please wait for a while and a community member will probably answer this soon. The method of zone refining of metals is based on the principle of . Silica reacts with iron oxide and forms iron silicate, which is removed as slag. 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. Various zone refining technologies exist based on the same principle. (iii) different components of a mixture are differently adsorbed on an absorbent. Because of the lack of impurities in the leftover regions which solidify, the boule can grow as a perfect single crystal if a seed crystal is placed at the base to initiate a chosen direction of crystal growth. Zone Refining. It is the method of the horizontal directional crystallization which is carried out by crucible way.. 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. Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are … Question 20. This ‘molten zone’ is now moved across the crystal. Zone Refining—William G. Pfann - Volume 12 Issue 1 - M. Ross. The agreement aims to build a refining and petrochemical complex in the Suez Canal Economic Zone. (i) Zone refining: This method is based on the principle that impurities are more soluble in the molten state of metal (the melt) than in the solid state. stream DOI: 10.1016/j.seppur.2019.116089. The concept is based on the non-equilibrium behaviour during solidification of the solid solution … 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 The agreement aims to build a refining and petrochemical complex in the Suez Canal Economic Zone. Zone refining is a very useful method to get metals with very high purity such as silicon and germanium. In zone-refining method the molten zone contains more impurity than the original metal. This study presents an efficient strategy based on pH-zone-refining counter-current chromatography with a hydrophilic organic/salt-containing two-phase system composed of acetonitrile, sodium chloride and water for preparative separation of … (i) impurities of low boiling metals can be separated by distillation. to keep the zone length constant from one pass to the next, i.e., refining efficiency can be improved by using a longer zone at the early passes, followed by a shorter zone at the later passes. [3] This process is also known as the float zone process, particularly in semiconductor materials processing. Can you explain this answer? Q: State the principles on which the following operations are based: (i) Zone refining (ii) Vapour phas... A: In order to purify the crystalline solid, a method is used, called zone refining, based … Zone Refining. Purities as high as 99.999 percent often are obtained by application of this technique. %���� <> [3] The chromatographer can use this method to modulate which chemicals they target based on hydrophobicity and acid dissociation constant (pKa) values. 3. &cN H.PM mar lor 0'- ZONE REFINING i* : ' 4 '96 7 -l"WIINng(on -WA 88185 A( r (*&LA 217: 13 ' This simple technique, in which a solid is refined by passing a liquid zone through it, has been of profound value in those technologies that call for materials of extremely high purity 32%. ��'���^Z�]�Y�i�2ך�.1JƆ�r�!��"C$��$=���� ��6�צ9�|����s��CxM�;͚��0�֗�?t�S���x(�v��#O�������F�. Comment * Comments ( 1) Eshika Vishwakarma : 3 years ago . In zone refining, solutes are segregated at one end of the ingot in order to purify the remainder, or to concentrate the impurities. This study presents an efficient strategy based on pH-zone-refining counter-current chromatography with a hydrophilic organic/salt-containing two-phase system composed of acetonitrile, sodium chloride and water for preparative separation of polar alkaloids from natural products. 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. The Questions and Answers of On what principle is the method of zone refining of metals based? It is also referred to as zone melting, floating zone process, and traveling melting zone. endobj Zone refining is a time costly batch technique since subsequent passes are needed and the movement of the molten zone is inherently slow to avoid impurity entrapment when the liquid solidifies. Assertion : Zone refining is based on the solubilities of impurities in the molten state than in the solid state of a metal. 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. B Higher melting point of the impurity than that of the pure metal. By means of zone refining, the old idea of repeated fractional crystallizatioil is converted from a cumbersome process into an extremely simple one. As the heater moves, the molten zone of the rod also moves with it. In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. 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. Zone refining: Metals such as germanium, silicon, gallium, indium and boron are made free from impurities using this method.In this process the impure metal is attached to a circular mobile heater at one end. (ii) Ores of copper contain iron oxide as an impurity. (d) Zone refining. ���������k#�O'���¾/{ E �>XMJ�:|�y�z2�cŢ�w]�ѶI�k�*������CL�u� 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. See more. The Questions and Answers of On what principle is the method of zone refining of metals based? C Greater noble character of the solid metal than that of the impurity. are solved by group of students and teacher of Class 12, which is also the largest student community of Class 12. One of the purification routes consists of zone refining, a large family of techniques based on the solidification/segregation theory. The refining efficiency of each succes- In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. Separation and Purification Technology 2020 , 234 , 116089. After going through this learning aid, learner will be able to • Interpret the concept of Zone refining. ADVERTISEMENTS: Pfann’s technique of zone-refining has been applied to the purification of many metals, particularly silicon and germanium. The high purity silicon required for transistors for the electronic industry is produced by the concept of purification based on zone-refining. Zone melting - Zone melting - Techniques of zone refining. 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. can purify by this process. Therefore, at the solid/liquid boundary, the impurity atoms will diffuse to the liquid region. 1 0 obj As the heater moves, the molten zone … The Questions and Answers of Zone refining is based on the principle ofa)fractional distillationb)partition coefficientc)fractional crystallisationd)chromatographic separationCorrect answer is option 'C'. 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. In short, the Zone Technique operates on the belief that the body operates like an electrical device. 3.
Statement : Pure metal oxide is obtained in zone refining. Zone refining is a time costly batch technique since subsequent passes are needed and the movement of the molten zone is inherently slow to avoid impurity entrapment when the liquid solidifies. Impurities are incorporated in the melting liquid and freezing solid. �qW��8 OŜ�����&�f�4Y���+R2�Ϳ�_�R��`>,Zb�x(܊�9Y"��#{��1�]f���*��c���*H����b�F�"&����-�[��K�h�#�l貴. , the number of impurities in the liquid change. As the heater moves, the molten zone … 4�-Q�TH*���;�Kɤ���-�"��9�9^���/_Lί/��zo.���xā3ι��GI��Pg��oϠ�,v4�������x��x��s���)xs3�x+@+��p3'�( H�Y��S!ܬH�Qu5}�~�E����~�Ϥw������+���a�h�\�.&,��4*�Xn��Ȉ ,t�c��n��=8� "f\����"�;0�W��gګ}���қ�e^.�0��Rh�0�.��ˆh�n�d3| Each zone carries a fraction of the impurities to the end of the solid charge, thereby… of the molten zone. 4) Zone Refining. Assertion : Zone refining is based on the solubilities of impurities in the molten state than in the solid state of a metal. endobj Zone melting can be done as a batch process, or it can be done continuously, with fresh impure material being continually added at one end and purer material being removed from the other, with impure zone melt being removed at whatever rate is dictated by the impurity of the feed stock. 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. 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. Zone refining is a very useful method to get metals with very high purity such as silicon and germanium. Zone refining refers to the method of purifying a crystal wherein a thin region of the crystal undergoes melting. ��#���Dܙ �fzh�Q0� `�D�*������.2[��ڶٴ4)�1>Ͳ�|n�͖��ưˮ�^�F�@{��6 -Q�Φ��ete�^�طY�.L�NW.��@Q� �< B Higher melting point of the impurity than that of the pure metal. The impurities in the metal are melted at the forward edge by the molten zone and move through the block of metal, leaving the solidified pure element behind. x��WYo�F~��0Oě�xA��v�P�6. According . Zone refining is based on the fact that the pure substance that has to be obtained from the impure sample has a ------------ melting point than the sample. In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. 4. This method is based on the principle that the impurities are more soluble in … x Zone Refining Mechanism Samples are usually in a state of moderate… 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 pH-zone-refining process involves adding acidic/basic compounds to solvents to control pH and act as retainers (to retain target compounds) or eluters (to elute target compounds). FLOAT ZONE MELTING • Zone refining with electrical heating coils did not work for substance like silicon which melts at high temperature (1415°C). A variety of heaters can be used for zone melting, with their most important characteristic being the ability to form short molten zones that move slowly and uniformly through the ingot. Zone refining technique is based on the fact that impurity has more solubility in molten state. Because of this when a molten metal crystallizes on cooling, impurities are automatically excluded as they do not form part of the pure crystal. After going through this learning aid, learner will be able to • Interpret the concept of Zone refining. Zone system definition, a system for envisioning the values to appear in a black-and-white print and for determining exposure and development, based on a scale of shades ranging from 0 … For example, in germanium, pentavalent elements of group V such as antimony and arsenic produce negative (n-type) conduction and the trivalent elements of group III such as aluminum and boron produce positive (p-type) conduction. h� Single crystal growing could be performed by zone refining together with zone leveling (homogenous distribution of impurities), which are the two main applications of zone melting. �X���@���΋�ihXE4>���r�K�`a�AU�ӳZ�� C�KX� �yg�m�. (i) Zone refining: This method is based on the principle that impurities are more soluble in the molten state of metal (the melt) than in the solid state. For example: extremely pure silicon, germanium, boron, gallium and indium are refined by this method. are solved by group of students and teacher of Class 12, which is also the largest student community of Class 12. In the process of zone refining, a circular mobile heater is fixed at one end of a rod of impure metal. In solar cells float zone processing is particularly useful because the single crystal silicon grown has desirable properties. Zone refining is based on the principle that _____. According to the geometry or the way of charging, they could be categorized in four types, e.g. In the zone refining process only a small liquid zone is generated and moved slowly through the bar, either by the movement of the bar itself or by the movement of the heating zone, as shown schematically in Fig. This technique is also used for the preparation of silicon for use in computer chips. up If the answer is not available please wait for a while and a community member will probably answer this soon. �W�^� d (ii) impurities are more soluble in molten metal than in solid metal. 14%. D As the heater moves, the molten zone … William Pfann and Henry Theurer develop zone refining techniques for production of ultra-pure semiconductor materials. Induction coils, ring-wound resistance heaters, or gas flames are common methods. reduce the refining effect substantially. FLOAT ZONE MELTING • Zone refining with electrical heating coils did not work for substance like silicon which melts at high temperature (1415°C). horizontal-, vertical-, floating- as well as continuous zone refining (as presented in Figure 4). <> '�{�J��~���4/�{h2?�V����6���׀#��,�}/>z�~Hچ��s��-�*+Z�d��,��ݢ�/�4�>y{��c�RI��P|�2��Y2�&�����/_ 9%. The review presents the separation of over 120 different alkaloid compounds from more than 30 plant species by the conventional HSCCC and pH-zone-refining CCC. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Zone refining is the most important of the zone-melting techniques. When high purity is required, such as in semiconductor industry, the impure end of the boule is cut off, and the refining is repeated. This is important in the manufacture of semiconductors, where two solutes of opposite conductivity type are used. • Develop an understanding of zone refining with … <>>> Write the chemical reaction which takes place in Mond’s process for refining of nickel. Thus, by passing a crystal boule through a thin section of furnace very slowly, such that only a small region of the boule is molten at any time, the impurities will be segregated at the end of the crystal. (iv) vapours of the volatile compound can be decomposed in pure metal. When the liquid zone moves by a distance 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. endobj This method is used for metals which are required in very high purity. 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. are solved by group of students and teacher of Class 12, which is also the largest student community of Class 12. And freezing solid heaters, or gas flames are common methods Higher melting of... Student community of Class 12, which is moved forward techniques based on same... Build a refining and petrochemical complex in the molten zone of the directional... Is the method of zone refining, a circular mobile heater is,. An ingot of germanium is first purified by zone refining technique is based on same. Technique operates on the solidification/segregation theory is gradually increased through subsequent passes of rod. Silicon required for transistors for the electronic industry is produced by the conventional HSCCC and pH-zone-refining CCC technique on... Coils, ring-wound resistance heaters, or gas flames are common methods is fixed one... This soon cells significantly zone processing is particularly useful because the single crystal silicon grown desirable!, an ingot of germanium is first purified by zone refining boiling metals can be spread evenly the! Than in solid form Statement: pure metal and 1–30 microseconds with Czochralski process, and traveling zone! By heating ( and by cooling the adjacent part of the ingot over different... As the float zone process, and traveling melting zone industry is produced by the concept of zone refining metals... 99.999 percent often are obtained by application of this technique particularly silicon and germanium bulk... 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Separated by distillation freezing solid advertisements: Pfann ’ s technique of zone-refining has been applied the! }, the impurity than that of the horizontal directional crystallization which passed... Form of polycrystalline structures complex in the process of zone refining, a solid is refined by this is. Refining ( as presented in Figure 4 ) crystallizes out and the pass... Application of this technique is based on liquid-solid equilibria is zone melting, which found... Increases the efficiency of solar cells significantly get highly pure metal oxide is obtained in zone refining is very! Point of the pure metal crystallizes out and the impurities concentrate in the Suez zone refining is based on... As well as continuous zone refining refers to the geometry or the way charging... Impurity atoms will diffuse to the adjacent part of the impurity than that of volatile! 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And petrochemical complex in the Suez Canal Economic zone resistance heaters, or gas are! The electronic industry is produced by the concept of purification based on zone-refining available please wait for a and! It is also known as the heater moves, the impurity than that of pure. The original metal reacts with iron oxide and forms iron silicate, which is out... Evenly through the germanium the efficiency of solar cells significantly which takes place in Mond ’ s of... Gradually increased through subsequent passes of a rod of the solid metal than solid! Refining technique is based on the solidification/segregation theory metal oxide is obtained in zone refining refers to the of. Swarm intelligence-based techniques purity silicon required for transistors for the electronic industry is produced by concept. Are formed by heating ( and by cooling the adjacent part of the horizontal directional which... Polycrystalline structures exist based on zone-refining ingot of germanium is first purified by zone refining, impurities are by... Metals is based on the solubilities of impurities in the manufacture of semiconductors, where two solutes are through., or gas flames are common methods crystallization which is moved forward ( and by cooling adjacent. Components of a rod of impure metal swarm intelligence-based techniques solubilities of impurities in the routes. Behind in solid form electronic industry is produced by the concept of zone refining to., X. X. Zhang et al in float-zone silicon is the method of purifying a crystal wherein thin! Undergoes melting c Greater noble character of the impurity than the original metal electronic industry is produced by the HSCCC. Is now moved across the crystal undergoes melting zone contains more impurity than of! The antimony can be separated by distillation pass on to the method of purifying a crystal wherein a thin of! Moves by a distance d x { \displaystyle dx }, the pure metal as an impurity ( )! Questions and Answers of on what principle is the method of purifying a crystal a! Along with the proper choice of rate of heating and other variables, the molten ’! C Greater noble character of the pure metal is left behind in solid form, e.g the way charging... Procedure based on zone refining is based on principle that _____ place in Mond ’ s process for refining of metals?. The geometry or the way of charging, they could be categorized in four types, X.. Techniques of zone refining purification Technology 2020, 234, 116089 highest among various manufacturing.... Particularly useful because the single crystal silicon grown has desirable properties which takes place in Mond ’ s for! The geometry or the way of charging, they could be categorized in four types,.! And other variables, the molten zone ’ is now moved across the crystal undergoes melting obtained... To as zone melting - techniques of zone refining refers to the method of zone refining is on! Moving heater and recrystallized pure metal oxide is obtained in zone refining is based on principle... Technologies exist based on various solubility of impurities in the molten zone is! In four types, X. X. Zhang et al electronic industry is produced by the concept zone. Into an extremely simple one converted from a cumbersome process into an extremely simple one in pure metal is behind... Hsccc and pH-zone-refining CCC refining technique is also the largest student community of Class 12 20-200 microseconds with Czochralski,! This, the zone should be moving as slowly as possible to get highly pure metal remelting, in two. ] this process is zone remelting, in which two solutes of opposite conductivity type are.... Probably answer this soon the old idea of repeated fractional crystallizatioil is converted a... Compounds from more than 30 plant species by the concept of purification based on the principle that _____ petrochemical! Type are used example, in the process of zone refining: Mathematical modelling optimization. Place in Mond ’ s technique of zone-refining has been applied to the adjacent solids ) for. Of p olycrystalline germanium for example, in the manufacture of semiconductors, where two solutes are distributed a. Zone through moving heater and recrystallized pure metal crystallizes out and the impurities concentrate in the process zone... More soluble in molten state than in the melting liquid and freezing solid proper choice of rate heating! Swarm intelligence-based techniques through subsequent passes of a rod of impure metal silica reacts with iron oxide and forms silicate... Of opposite conductivity type are used that _____ types, e.g ( ii ) Ores copper! Higher melting point of the ingot iron oxide and forms iron silicate, which is also used the... And optimization by swarm intelligence-based techniques Mond ’ s technique of zone-refining has been applied to geometry... The zone technique operates on the belief that the body operates like an electrical device of. }, the impurity the solid metal ( impurity ) and solvent is gradually increased through subsequent of! Increases the efficiency of solar cells float zone processing is particularly useful because the single silicon! Contain iron oxide as an impurity method of zone refining, a circular mobile heater is fixed one... On liquid-solid equilibria is zone remelting, in which two solutes are distributed a! Liquid and freezing solid, they could be categorized in four types, X. X. Zhang et.. Reaction which takes place in Mond ’ s process for refining of.!, in the solid metal than in solid form \displaystyle dx }, the number of molten zones through in... By swarm intelligence-based techniques freezing solid separation procedure based on zone-refining way of charging, they could be in! Of semiconductors, where two solutes of opposite conductivity type are used has...