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Topic: Zone refining

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	Zone melting - Wikipedia, the free encyclopedia
		Zone melting is a method of separation by melting in which a series of molten zones traverses a long ingot of impure metal or chemical.
		Zone refining was developed by the Bell Telephone Laboratories as a method to prepare high purity materials for manufacturing transistors.
		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.
	en.wikipedia.org /wiki/Zone_melting (506 words)

	Refining - Wikipedia, the free encyclopedia
		Refining is the process of purification of a substance.
		The refining of liquids is often accomplished by distillation or fractionation.
		Many solids can be refined by growing crystals in a solution of the impure material; the regular structure of the crystal tends to favor the desired material and exclude other kinds of particles.
	en.wikipedia.org /wiki/Refining (232 words)

	Patent 4888051: Method for the zone refining of gallium
		The zone refining of gallium has been practised in the past, but it is noted in many references that the process is difficult to execute because of the low melting temperature of gallium, its high degree of expansion upon solidifying and its relatively high thermal conductivity.
		In the assembly of zone refiner 1, a sleeve of heat-shrinkable Teflon.TM.
		After cropping the ingot, the remaining portion of the refined gallium is removed from the refiner by melting the gallium either by applying RF heating or by flowing hot water through the inner tube 2 and draining the molten gallium from the bottom of the refiner through opening 16.
	www.freepatentsonline.com /4888051.html (4366 words)

	Patent 4220626: RF Induction heating circuits for float zone refining of semiconductor rods
		Apparatus for zone refining rods of semiconductive material is disclosed including an RF induction work coil having a single turn lying in a plane generally transverse to the lengthwise axis of the rod and encircling the rod.
		In zone refining, there is an interaction between the heat of the melt (i.e., the heat of the molten mass of semiconductor material constituting the molten zone), the size of the molten zone (which effects the magnitude of the RF load) and the power output of the oscillator circuit.
		In carrying out zone refining, the specific rates of relative movement between work coil 29 and rod 13, control of the gaseous environment within chamber 11, and other specific process parameters are beyond the purview of this description and are not necessary for an understanding of the present invention.
	www.freepatentsonline.com /4220626.html (4266 words)

	Zone melting (Site not responding. Last check: 2007-11-04)
		In zone refining, solutes are segregated at one end of the ingot in order to purify the remainder, or to concentrate theimpurities for analytical or other purposes.
		In zone leveling, the objective is to distribute solute evenlythroughout the purified material, which may be sought in the form of a single crystal.
		A variety of heaters can be used for zone melting, with their most important characteristic being the ability to form shortmolten zones that move slowly and uniformly through the ingot.
	www.therfcc.org /zone-melting-126346.html (393 words)

	Refining (Site not responding. Last check: 2007-11-04)
		Gases are refined this way as well, by being cooled untilthey liquefy.
		Many solids can be refined by growing crystals in a solution of the impure material; the regular structure of the crystal tends to favor the desiredmaterial and exclude other kinds of molecules.
		The use of silicon and other semiconductors in electronics is highly dependent onprecise control of impurities, and a number of special techniques have been developed, such as zone refining.
	www.therfcc.org /refining-143155.html (184 words)

	Applications (Site not responding. Last check: 2007-11-04)
		Schildknecht and Mannl (1957) reported that the zone refining of a crude benzene produced a fraction at the end of the sample that was liquid when the rest of the specimen was solid.
		After each zone pass all residual vapor was frozen into one of the traps by means of liquid nitrogen and the condensed vapor was isolated from the rest of the system.
		This compound was zone refined to a purity of 99.9 per cent by workers at the Bureau of Mines, Laramie, Wyo., U.S.A. (Ball, Helm and Ferrin, 1958, 1959).
	designscientific.com /applications.htm (3635 words)

	LPiNL6-95: Newsletter - Floating Zone Method
		By heating a very small region of the material to be refined to its molten state and controlling the movement of this zone, impurities can be extracted from the solid material and collected by the molten or liquid zone.
		Since the floating zone method is capable of growing single crystals with a given orientation, as well as zone refining and leveling, it is ideally suited to the production of silicon crystals for semiconductor devices.
		While the processing details for zone refining and growing single crystals of silicon vary from plant to plant, the equipment and procedure described here have proven successful for processing silicon rods up to 1-1/4 inches (31.75 mm) in diameter.
	www.lepel.com /IND/nl198.htm (855 words)

	Preliminary Process Analysis (Site not responding. Last check: 2007-11-04)
		Refining is performed at approximately 55% consistency with a target freeness of approximately 350 ml.
		As refiners are fed volumetrically, changes in chip packing density cause variation in specific energy which in turn cause variations in pulp quality.
		When the refiners were placed under consistency control, approximately 80% of the predicted variation in blowline consistency was removed from the refiner operation.
	www.pacsim.com /Articles/qcofhcr/qcofhcr.htm (2927 words)

	Liquid encapsulated zone melting crystal growth method and apparatus - US Patent 5057287 (Site not responding. Last check: 2007-11-04)
		A lower thermal gradient subzone 10 is located between the bottom of the central zone heating element and the lower furnace zone 5, and an upper thermal gradient subzone 12 is located between the top of the central zone heating element and the upper furnace zone 7.
		By maintaining a molten region within the spike zone which is considerably shorter in length than the lengths of the surrounding upper and lower furnace zones, the resulting growth interface shape is slightly convex with respect to the solid phase of the material, and an optimal single crystal can be grown.
		The temperature of the molten subzone within the spike zone was again permitted to drop to a temperature in the range from 1100° to 1200° C., and the crystal growth container was raised all the way to the top of the furnace and the support rod was clamped in position.
	www.patentstorm.us /patents/5057287.html (6928 words)

	Zone Refining (Site not responding. Last check: 2007-11-04)
		In zone refining, a heater melts a small region at a time.
		After a molten zone is passed along the rod from left to right, the impurities are more concentrated at the right.
		In practice, a series of molten zones are passed along the rod.
	www.westga.edu /~chem/courses/chem410/3510_04/sld050.htm (45 words)

	Zone refining (cont.) (Site not responding. Last check: 2007-11-04)
		The results on the left of the previous slide are for zone refining a material that is 11 zone lengths long or longer.
		The impurities are swept out of the ten zone lengths on the left side of the crystal.
		After zone refining is completed the leftmost part of the crystal can be cut off and will have a low level of impurities.
	www.mse.berkeley.edu /classes/mse120/AdvanMats/tsld015.htm (114 words)

	Junction Transistor Manufacture
		The refining is continued by this process until the impurities with electrical activity are reduced to the order of one part in ten thousand million-1 in 10^10.
		The zone refiner consists of a silica tube surrounded at intervals by r.f.
		The ingot of germanium as it comes from the zone refiner consists of many small crystals of different sizes, the axes of which are arranged at random.
	www.thevalvepage.com /trans/manufac/manufac1.htm (2735 words)

	Juniata College - Mifflin County - CTP Project
		In refining this zone, the width of the floodplain remained a constant factor.
		Zone AE's are 100-year flood areas that already have base flood elevations and flood hazard factors associated with them.
		Once the zone A and AE floodplains were edited, the corrections were sent to a project coordinator for Quality Assurance and Quality Control (QA/QC), a final check to assure that the new adjustments meet FEMA's standards.
	projects.juniata.edu /fema/details.htm (318 words)

	MODEL BASED CONTROL OF HIGH CONSISTENCY (Site not responding. Last check: 2007-11-04)
		The refiner consistency control system is implement in a TMP mill producing newsprint quality pulp from a combination of pine, spruce, fir and hemlock.
		Refining is performed at approximately 60% consistency with a target freeness of approximately 350 ml.
		The secondary refiner displays increased motor load variation compared to the primary refiner (the primary cause for short term consistency variation) due to more difficulty in feeding as well as sensitivity to variations in fiber consistency from the primary refiner.
	www.pacsim.com /Articles/Mod_base/MOD_BASE.HTM (3169 words)

	Metals and non-metals/General Metallurgy - The Process of Extraction of Metals from their Ores and Refining them
		The various processes involved in the extraction of metals from their ores and refining them are known as metallurgy.
		Refining can also be used to recover some valuable by-products such as silver or gold.
		As the heater moves ahead, the impurities are swept forward in the molten zone.
	www.nedians.8m.com /Physical.html (1532 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		The zone refining process was applied to Pu metal containing known amounts of impurities.
		As the impurity alloy was zone refined, {delta}-phase plutonium metal crystals were produced.
		The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=10171839 (266 words)

	#1 Site For Learning Chemistry
		In an electrolytic cell, a block of impure metal is made into the anode, a thin strip of pure metal is made into a cathode, and an electrolyte is made out of a suitable metal-salt of the metal to be refined.
		2) Zone refining : This method applies the fact when a metal crystallizes on cooling, impurities are automatically expelled as they do not form part of the crystal.
		As the heater is moved to the right, the ultra-pure Ge moves in the left direction and the impurities move in the opposite direction.
	home.att.net /~cat6a/metals-XI.htm (858 words)

	Clarion Fracture Zone -- Encyclopædia Britannica
		Typically, a regional depth offset is present across a fracture zone, owing to the...
		The fracture zone is incompletely mapped but may be as long as 3,700 miles (5,900 km), extending east-southeastward from east of the Tuamotu archipelago, at 20° S latitude and 131° W longitude, to the Peru-Chile Trench at the 26° S latitude.
		The fracture zone is more than 7,240 km (4,500 miles) long, trending east-northeast along a global small circle from the vicinity of the Line Islands at about...
	www.britannica.com /eb/article?tocId=9024198 (745 words)

	photic zone -- Encyclopædia Britannica (Site not responding. Last check: 2007-11-04)
		The uppermost 80 m (260 feet) or more of the ocean, which is sufficiently illuminated to permit photosynthesis by phytoplankton and plants, is called the euphotic zone.
		Sunlight insufficient for photosynthesis illuminates the disphotic zone, which extends from the base of the euphotic zone to about 200 m.
		For example, some types of plankton, fish, and squid remain beneath the photic zone during the day, moving toward the surface after dusk and returning to the depths before dawn.
	www.britannica.com /eb/article?tocId=9059790 (796 words)

	(WO 01/37998) REFINER PLATES WITH INJECTOR INLET (Site not responding. Last check: 2007-11-04)
		The refiner plates each have radially inner and outer edges and an inlet zone extending radially outward from the inner edge.
		The inner portion of the rotor plate includes a plurality of breaker bars which curve in a direction which is opposite to the direction of rotation of the rotor plate and which extend to a height substantially equal to one-half of the refining gap.
		The outer portion of the inlet zone of the rotor plate and the inner portion of the inlet zone of the stator plate may each have either a smooth surface or a plurality of outwardly extending low profile protrusions.
	wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/37998.010531&... (270 words)

	Semiconductor Crystal Pulling With Induction Heating
		In the semiconductor manufacturing process, the refining and subsequent doping of silicon and germanium crystals is of utmost importance.
		By causing a molten zone of the material to travel along a rod of the material, impurities can be left at one end.
		Zone refining produces impurity levels based on the number of passages made along the rod by the molten zone.
	www.ameritherm.com /overview_crystalpulling.html (478 words)

	Abstract 13: Numerical Analysis on Optimal Zone Lengths for Each Pass in Multipass Zone-Refining Processes (Site not responding. Last check: 2007-11-04)
		The effect of zone length on the separation efficiency in multipass zone-refining processes has been investigated theoretically.
		In multipass operations, the optimal zone lengths in each pass and their corresponding maximum fraction of solute removal were obtained with distribution coefficients k and number of passes n as parameters.
		The results showed the optimal zone lengths for all passes increase with distribution coefficient, but decrease with pass number.
	www.cjche.ca /journal/issues/feb98/13-9802.html (248 words)

	Nuteeriat: Geoprospecting and Mineral Riches
		In one zone refining method, a slab of the metal or compound to be refined is placed in a trough along which a heating ring can be passed in a slow and regular manner.
		The ring is gradually moved to the other end of the trough and the heat turned off, as one cycle of refining is finished.
		What this process does is to dissolve minor impurities in the liquid zone as it reaches them, and continue to carry the impurities in the liquid zone as this moves to the other end of the trough.
	www.aoi.com.au /matrix/Nut04.html (2591 words)

	MSN Encarta - Search Results - zone refining
		Zone (geography), any of the five divisions of the surface of the earth, characterized by similar temperature and sunshine distribution.
		A bishop of the Greek Orthodox church, when attired for Divine Liturgy (corresponding to the Mass of the Roman Catholic church), wears a cassock over...
		Map of Franc Zone (map of member countries)
	encarta.msn.com /zone+refining.html (151 words)

	Zone Refining - Find Zone Refining Suppliers, Zone Refining Manufacturers and Zone Refining Distributors
		Power Sourcing is your best source for finding zone refining suppliers.
		We are dedicated to bringing qualified zone refining buyers and suppliers together.
		Find a supplier of zone refining and thousands of other products and services for purchasing and research.
	www.powersourcing.com /se/zonerefining.htm (176 words)

	High Purity Chemicals
		For example, we are equipped to carry out zone refining of chemicals, from –65
		In many cases, the impurities concentrated by zone refining are of as much interest as the pure product, since the impurity-enriched material facilitates qualitative analysis by coupled chromatography/spectrometry.
		Zone refining may be carried out to provide pure material, or to demonstrate feasibility of other, large-scale melt-crystallization methods.
	www.norquaytech.com /highpurity.htm (322 words)

	Zone melting - TheBestLinks.com - Zone refining, Arsenic, Antimony, Aluminium, ... (Site not responding. Last check: 2007-11-04)
		Zone melting - TheBestLinks.com - Zone refining, Arsenic, Antimony, Aluminium,...
		Zone refining, Zone melting, Arsenic, Antimony, Aluminium, Boron, Crystal...
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	www.thebestlinks.com /Zone_refining.html (547 words)

	Search Results for "zone refining"
		In October 2002, Bahrainis elected members of the lower house of Bahrain's reconstituted...
		The city, which is a special economic development zone, has textile, chemical, shipbuilding, sugar refining, and electric power industries,...
		refining wastes; inadequate potable waterEnvironment-international agreements:party to: Biodiversity, Climate Change, Desertification, Hazardous Wastes, Nuclear Test...
	www.bartleby.com /cgi-bin/texis/webinator/sitesearch/+LwwFqDSdDnaGnhoDoDtxzmwwwwmFqMqdc2nhnGnDqnnFqMqdc2nhnGnDqn (242 words)

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