Reducing In Gaseous Suspension Patents (Class 75/443)
  • Patent number: 11465199
    Abstract: A runner apparatus for preventing thermal loss of molten materials, wherein the runner apparatus guides the molten materials discharged from a furnace to a casting mold, including: an insulation unit providing a passage for a flow of the molten materials discharged from the furnace and lowering a thermal loss of the molten materials; a dam unit confining the insulation unit in a predetermined space thus preventing a leak and adjusting the flow of the molten materials; an outside unit forming an exterior wall covering the insulation unit; and a spread unit, disposed under the insulation unit, spreading the molten materials dropping from the dam unit and transferring the same to the casting mold.
    Type: Grant
    Filed: September 11, 2020
    Date of Patent: October 11, 2022
    Assignee: JPS CO., LTD.
    Inventor: Dong-Hoon Yeo
  • Patent number: 9725778
    Abstract: Direct reduction process and plant for producing DRI comprising a reduction reactor and at least one reducing gas heater typically comprising a convective heating section and a radiant heating section for raising the reducing gas temperature to a level adequate for iron oxides reduction to metallic iron, typically above 850° C., wherein the reducing gas fed to the reduction reactor comprises a stream of reducing gas recycled from the reduction reactor and a make-up stream of coke oven gas containing carbon compounds which may form carbon deposits in the heating path of said heater, namely BTX and other complex carbon compounds. The heater is provided with means for feeding oxidizing agents, for example steam, steam and air and/or oxygen at predetermined heating tubes successively for eliminating the carbon deposits which may form inside the heating tubes of said heater without interrupting the operation of the plant.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: August 8, 2017
    Assignees: HYL TECHNOLOGIES, S.A. DE C.V., DANIELI & C. OFFICINE MECCANICHE, S.P.A.
    Inventors: Alessandro Martinis, Jorge-Octavio Becerra-Novoa, Michele Condosta, Eugenio Zendejas-Martinez
  • Patent number: 8968441
    Abstract: A method and a plant for the production of pig iron or liquid steel semi-finished products are shown, metal oxide-containing batch materials and, if appropriate, aggregates being at least partially reduced in a reduction zone by a reduction gas, subsequently being introduced into a smelting zone and being smelted along with the supply of carbon carriers and oxygen-containing gas and along with the formation of the reduction gas. The reduction gas formed in the smelting zone is supplied to the reduction zone, reacted there and drawn off as export gas, CO2 is separated from the export gas, and a product gas is formed which is utilized for the introduction of pulverulent carbon carriers into the smelting zone.
    Type: Grant
    Filed: January 14, 2010
    Date of Patent: March 3, 2015
    Assignee: Siemens Vai Metals Technologies GmbH
    Inventor: Robert Millner
  • Patent number: 8911700
    Abstract: A process and an installation for reducing particulate material containing iron oxide are shown, wherein the material containing iron oxide is at least partially reduced with reducing gas in a reducing zone and the waste gas produced during the reduction is drawn off and subsequently subjected to CO2 cleaning in a CO2 separating device (1), in which a tail gas containing CO2 is separated. The tail gas is subjected to combustion and subsequent dewatering in a dewatering device (5), the substitute gas thereby formed being used as a substitute for inert gas.
    Type: Grant
    Filed: February 3, 2010
    Date of Patent: December 16, 2014
    Assignee: Siemens Vai Metals Technologies GmbH
    Inventors: Robert Millner, Jan-Friedemann Plaul, Kurt Wieder
  • Patent number: 8632622
    Abstract: A process for producing pig iron or liquid primary steel products in a smelting unit (1), in particular a melter gasifier. Iron-ore-containing charge materials, and possibly additions, are at least partially reduced in at least one reduction unit (R1, R2, R3, R4) by means of a reducing gas. A first fraction of the at least partially reduced charge materials is melted down in the smelting unit (1), while carbon carriers and oxygen-containing gas are supplied, with the simultaneous formation of the reducing gas. The reducing gas is fed to the reduction unit (R1, R2, R3, R4) and, after the reducing gas has passed through the reduction unit, it is drawn off as top gas. A second fraction of the at least partially reduced charge materials is fed to a smelting reduction unit for reducing and smelting.
    Type: Grant
    Filed: April 27, 2009
    Date of Patent: January 21, 2014
    Assignee: Siemens Vai Metals Technologies GmbH
    Inventors: Christian Boehm, Jan-Friedemann Plaul, Johannes Leopold Schenk
  • Patent number: 8377168
    Abstract: A process for reducing iron ore particles in a moving bed reduction reactor comprising an upper reduction zone and a lower discharge zone, wherein coke oven gas, preferably forming all the make-up for the reducing gas circulating through and reacting in the reduction zone, is first fed to the discharge (and, optionally, cooling) zone and thereafter, conditioned by the DRI in the lower zone, is withdrawn from the reactor and transferred externally into the recycle reducing gas for injection into the reduction zone; with the heavy hydrocarbons and other components of coke oven gas which cause fouling, corrosion, or deposits in the direct reduction plant being removed from coke oven gas by catalytic and/or adsorptive action of the DRI in the lower zone; preferably the gas flow rate of the coke oven gas and the externally transferred gas differs between about 100 and 200 NCM per ton of DRI produced.
    Type: Grant
    Filed: January 5, 2007
    Date of Patent: February 19, 2013
    Assignee: HYL Technologies, S.A. DE C.V.
    Inventors: Eugenio Zendejas-Martinez, Pablo-Enrique Duarte-Escareño
  • Publication number: 20120036961
    Abstract: A method and a plant for the production of pig iron or liquid steel semi-finished products are shown, metal oxide-containing batch materials and, if appropriate, aggregates being at least partially reduced in a reduction zone by a reduction gas, subsequently being introduced into a smelting zone and being smelted along with the supply of carbon carriers and oxygen-containing gas and along with the formation of the reduction gas. The reduction gas formed in the smelting zone is supplied to the reduction zone, reacted there and drawn off as export gas, CO2 is separated from the export gas, and a product gas is formed which is utilized for the introduction of pulverulent carbon carriers into the smelting zone.
    Type: Application
    Filed: January 14, 2010
    Publication date: February 16, 2012
    Inventor: Robert Millner
  • Patent number: 8038766
    Abstract: A direct reduction process for a metalliferous material includes supplying the metalliferous material, a solid carbonaceous material, an oxygen-containing gas, and a fluidizing gas into a fluidized bed in a vessel and maintaining the fluidized bed in the vessel, at least partially reducing metalliferous material in the vessel, and discharging a product stream that includes the partially reduced metalliferous material from the vessel. The process comprises (a) reducing the metalliferous material in a solid state in a metal-rich zone in the vessel; (b) injecting the oxygen-containing gas into a carbon-rich zone in the vessel with a downward flow in a range of ±40° to the vertical and generating heat by reactions between oxygen and the metalliferous material (including metallized material), the solid carbonaceous material and other oxidizable solids and gases in the fluidized bed, and (c) transferring heat from the carbon-rich zone to the metal-rich zone by movement of solids within the vessel.
    Type: Grant
    Filed: May 20, 2005
    Date of Patent: October 18, 2011
    Assignee: Outotec Oyj
    Inventors: Andreas Orth, Heinz Eichberger, Donald Keith Philp, Jeantine Van Gemund, legal representative, Rod Dry
  • Patent number: 7854909
    Abstract: A process for treating a finely particulate, in particular metal-containing, charge material: The charge material and a treatment gas, in particular a reduction gas, are introduced into a fluidized bed chamber of a fluidized bed reactor to form a fluidized bed. After at least partial reaction in the fluidized bed, the treatment gas is discharged from the fluidized bed and, outside the fluidized bed, is at least partially reprocessed, preferably oxidized, by an exothermic, chemical reaction with a reactant, preferably with a gaseous and/or liquid oxidizing agent. The thermal energy of this reaction is at least partially introduced into the fluidized bed chamber, in particular into the fluidized bed, or being discharged therefrom to affect the temperature of the particulate material above the bed. Also an apparatus for operating such a fluidized bed includes the chamber, lines into and out of the chamber for gas and material and a cyclone at the chamber for the material.
    Type: Grant
    Filed: October 23, 2002
    Date of Patent: December 21, 2010
    Assignee: POSCO
    Inventors: Johann Zirngast, Albert Zschetzsche
  • Patent number: 7781018
    Abstract: This invention discloses a method of making an oxygen scavenging particle comprised of an activating component and an oxidizable component wherein one component is deposited upon the other component from a vapor phase and is particularly useful when the activating component is a protic solvent hydrolysable halogen compound and the oxygen scavenging particle is a reduced metal.
    Type: Grant
    Filed: November 23, 2009
    Date of Patent: August 24, 2010
    Assignee: M&G USA Corporation
    Inventor: Kevin L. Rollick
  • Patent number: 7622153
    Abstract: This invention discloses a method of making an oxygen scavenging particle comprised of an activating component and an oxidizable component wherein one component is deposited upon the other component from a vapour phase and is particularly useful when the activating component is a protic solvent hydrolysable halogen compound and the oxygen scavenging particle is a reduced metal.
    Type: Grant
    Filed: August 3, 2005
    Date of Patent: November 24, 2009
    Assignee: M&G USA Corporation
    Inventor: Kevin L. Rollick
  • Patent number: 7615098
    Abstract: A method of obtaining a measure of the stickiness of heated particulate solids (40) includes pouring a sample of the particulate solids (40) onto a generally horizontal support (12) and allowing it to freely form its own angle of repose. The sample is subjected to a predetermined heat and gas atmosphere regime, and the support is rotated about a generally horizontal axis to an angle (42) where the integrity of the sample (40) fails. The angular position (42) is a measure of the stickness of the particulate solid (40).
    Type: Grant
    Filed: December 29, 2004
    Date of Patent: November 10, 2009
    Assignee: BHP Billiton Innovation Pty. Ltd.
    Inventors: Allon Dudley Brent, Peter Leonard John Mayfield, Dean Page Crawford, Thomas Alexander Honeyands, Andrew Shook, Damien O'Dea
  • Publication number: 20090211401
    Abstract: A process for reducing iron ore particles in a moving bed reduction reactor comprising an upper reduction zone and a lower discharge zone, wherein the coke oven gas, preferably forming all the make-up for the reducing gas circulating through and reacting in said reduction zone, is first fed to said discharge (cooling) zone and thereafter said coke oven gas, conditioned by the DRI in the lower zone, is withdrawn from the reactor and fed preferably into the recycled reducing gas for injection into the reduction zone of the reactor. Heavy hydrocarbons and other components of coke oven gas which may otherwise cause fouling, corrosion, or deposits in the direct reduction plant are removed from coke oven gas by catalytic and/or adsorptive action of the DRI present in said lower zone, before being externally transferred to the reduction zone of the reduction reactor.
    Type: Application
    Filed: January 5, 2007
    Publication date: August 27, 2009
    Inventors: Eugenio Zendejas-Martinez, Pablo-Enrique Duarte-Escareno
  • Publication number: 20030110891
    Abstract: The invention concerns a method for iron reduction to make sponge iron which consists in: depositing a feed of iron ore on a grate and moving the grate so as to cause the feed to pass in at least three different zones; inputting gases, called input gases into one or several zones, including a hot gaseous carbonaceous reducing agent, and forcing said input gases through the ore located on the grate; and capturing the gases resulting from said forced passage, called output gases. The passage of the input gases brings the ore to a temperature ranging between 850° C. and 1300° C.; maintaining said feed at said temperature until an iron ore metallizing rate ranging between 60% and 100% is obtained. The feed deposited on the grate consists of either iron ore calibrated between 5 mm and 40 mm, or iron ore pellets having a diameter ranging between 5 mm and 20 mm, or iron ore granules of size between 2 mm and 10 mm, and the thickness of the deposited layer ranges between 150 mm and 600 mm.
    Type: Application
    Filed: November 7, 2002
    Publication date: June 19, 2003
    Inventors: Bernard Vanderheyden, Rene Munnix
  • Patent number: 6165250
    Abstract: A separator for use in a direct reduction reactor comprises an elongated tubular housing having a cooling chamber for receiving a cooling medium for cooling the internal wall surface of the separator contacted by metallized iron fines.
    Type: Grant
    Filed: July 8, 1999
    Date of Patent: December 26, 2000
    Assignee: Brifer International Ltd.
    Inventors: Wolfgang A. Albarran, Adersido De Jesus Gomez, Oscar A. Dam
  • Patent number: 6051048
    Abstract: A first, solid, carbon-containing fuel is gasified and iron is melted in a gasifier-melter. A first flow of resulting fuel gas is employed to form the iron in a vertical shaft furnace by direct reduction of iron ore. A second flow of resulting fuel gas is mixed with fuel gas produced by separately gasifying a second carbon-containing fuel in a second gasifier, in which no iron is melted and which supplies essentially no carbonaceous solid fuel to the first gasification stage. This mixing helps to dampen fluctuations in the flow rate of the second flow of the resulting fuel gas.
    Type: Grant
    Filed: June 17, 1998
    Date of Patent: April 18, 2000
    Assignee: The BOC Group plc
    Inventor: Brian Anthony Keenan
  • Patent number: 5948139
    Abstract: In a process for the production of molten pig iron or steel pre-products from fine-particulate iron-cintaining material, in a meltdown-gasifying zone of a melter gasifier (1), under the supply of carbon-containing material and oxygen-containing gas at the simultaneous formation of a reducing gas, in a bed formed of sold carbon carriers, the iron-containing material is melted when passing the bed.
    Type: Grant
    Filed: April 17, 1997
    Date of Patent: September 7, 1999
    Assignees: Voest-Alpine Industrieanlagenbau GmbH, Pohang Iron & Steel Co., Ltd., Research Institute of Industrial Science & Technology Incorporated Foundation
    Inventors: Werner Leopold Kepplinger, Felix Wallner, Johannes Schenk
  • Patent number: 5647888
    Abstract: A process and a smelt reduction vessel (1) for producing metals and metal alloys, in particular iron and iron alloys, from metal oxides and ores in a smelt reduction vessel. The process and the vessel are characterized in that loss of liquid and solids with waste gases (11) from the vessel are minimized by causing the waste gases, oxidizing gases (5) and entrained liquid and solids in the space in the vessel that is above the molten metal to rotate about a vertical axis of the vessel thereby forcing liquid and solids outwardly toward the wall of the vessel. This rotational motion may be caused by injecting some or all the oxidizing gases through tuyeres (4) positioned above the bath surface obliquely to a vertical plane through a vertical axis of the vessel. The vessel may have a substantially rotationally symmetrical shape at least in the space above the molten metal (2A).
    Type: Grant
    Filed: May 2, 1995
    Date of Patent: July 15, 1997
    Assignee: CRA Services Limited
    Inventors: John Vincent Keogh, Robin John Batterham, Barry Stuart Andrews
  • Patent number: 5489325
    Abstract: A process and a smelt reduction vessel (1) for producing metals and metal alloys, in particular iron and iron alloys, from metal oxides and ores in a smelt reduction vessel. The process and the vessel are characterized in that loss of liquid and solids with waste gases (11) from the vessel are minimized by causing the waste gases, oxidizing gases (5) and entrained liquid and solids in the space in the vessel that is above the molten metal to rotate about a vertical axis of the vessel thereby forcing liquid and solids outwardly toward the wall of the vessel. This rotational motion may be caused by injecting some or all of the oxidizing gases through tuyeres (4) positioned above the bath surface obliquely to a vertical plane through a vertical axis of the vessel. The vessel may have a substantially rotationally symmetrical shape at least in the space above the molten metal (2A).
    Type: Grant
    Filed: November 3, 1992
    Date of Patent: February 6, 1996
    Assignee: CRA Services Ltd.
    Inventors: John V. Keogh, Robin J. Batterham, Barry S. Andrews
  • Patent number: 5464464
    Abstract: A method for reducing particulate iron oxide and/or other iron units to molten iron utilizing gaseous hydrogen as reductant in a reducing furnace, in which the ore freely falls during the melting and reduction process. Reacted top gas is purified and recirculated through the reduction furnace, establishing a counter-flow relationship to the particulate iron oxide, thereby heating and reducing the oxide. The heat for reduction is generated by combusting a fraction of the hydrogen reductant with oxygen. Heat may also be supplied via the use of electric arc heating. Oxygen may be partially or wholly replaced with water in order to maintain reaction oxidizer ratios while reducing heat supplied to the reaction.
    Type: Grant
    Filed: June 10, 1994
    Date of Patent: November 7, 1995
    Assignee: Borealis Technical Incorporated Limited
    Inventor: Jonathan Edelson
  • Patent number: 5431710
    Abstract: A fine particle mixture of iron concentrate and pulverized flux is introduced into the upper portion of the vertical prereduction section of a sealed unitary vessel. Heated gas partially reduces the iron concentrate particles to form wustite which falls to the lower portion where it is melted to form fluid slag. The slag passes into the horizontal section of the vessel which is divided by a barrier into a reduction portion and an oxidation portion. In the reduction portion, pulverized coal and oxygen are introduced and iron oxide in the slag is reduced to iron. The entrained iron droplets in the slag are permitted to sediment in a quiescent zone where the slag is removed. The molten iron may be recovered or converted into steel by flowing through passages in the lower portion of the barrier into the oxidation portion where oxygen is introduced to remove C, Si, P and other impurities and to convert iron into steel or semi-steel. The final product and slag are separately removed from the oxidation portion.
    Type: Grant
    Filed: April 14, 1993
    Date of Patent: July 11, 1995
    Inventor: Li W. Ebenfelt
  • Patent number: 5407460
    Abstract: A method for modifying existing direct reduction processes and retrofitting existing direct reduction facilities so as to increase the capacity of the facilities without the need for increasing the capacity of external reformers associated with the existing facilities comprises mixing preheated air with the reformed reducing gas produced in the external reformers and containing said mixture with excess natural gas in a reduction-reaction zone of the direct reduction reactor.
    Type: Grant
    Filed: March 10, 1994
    Date of Patent: April 18, 1995
    Assignee: C.V.G. Siderurgica Del Orinoco, C.A.
    Inventors: Henry R. Bueno C., Oscar G. Dam G., Pedro Torres, Felipe Gutierrez
  • Patent number: 5372628
    Abstract: A method for abating the incidence of cluster formation of reducible iron-containing material during the direct reduction of said material is disclosed. The method generally comprises contacting the reducible iron-containing material with a cluster-abating effective amount of a dispersion of a particulate material.
    Type: Grant
    Filed: September 10, 1993
    Date of Patent: December 13, 1994
    Assignee: Akzo N.V.
    Inventor: Harry R. G. Steeghs
  • Patent number: 5258054
    Abstract: A fine particle mixture of iron concentrate and pulverized flux is introduced into the upper portion of the vertical prereduction section of a sealed unitary vessel. Heated gas partially reduces the iron concentrate particles to form wustite which falls to the lower portion where it is melted to form fluid slag. The slag passes into the horizontal section of the vessel which is divided by a barrier into a reduction portion and an oxidation portion. In the reduction portion, pulverized coal and oxygen are introduced and the FeO in the slag is reduced to iron. The entrained iron droplets in the slag are permitted to sediment in a quiescent zone where the slag is removed. The molten iron flows through passages in the lower portion of the barrier into the oxidation portion where oxygen is introduced to remove C, Si, P and other impurities. The final product and waste are separately removed from the oxidation portion. Exhaust gases exit a vertical stack where heat is recaptured and dust particles removed.
    Type: Grant
    Filed: November 6, 1991
    Date of Patent: November 2, 1993
    Inventor: Li W. Ebenfelt
  • Patent number: 5226951
    Abstract: There is disclosed a method of starting a plant for the production of pig iron or steel pre-material including a direct-reduction shaft furnace and a meltdown gasifier.At first the still empty meltdown gasifier is heated up by aid of a combustible gas and the smoke gases forming are introduced into the still empty direct-reduction shaft furnace.Coke or a degassed coal product is charged into the direct-reduction shaft furnace and the smoke gases introduced into the direct-reduction shaft furnace are passed through the coke or the degassed coal product by releasing their sensible heat.The coke or the degassed coal product thereby is heated to ignition temperature and is charged into the meltdown gasifier in the hot state, catching fire upon the injection of an oxygen-containing gas or of oxygen.A further coal or coke bed serving for gasification is charged on the ignited bed of coke or degassed coal product and the charging substances are charged into the direct-reduction shaft furnace.
    Type: Grant
    Filed: February 19, 1992
    Date of Patent: July 13, 1993
    Assignee: Deutsche Voest-Alpine Industrieanlagenbav
    Inventors: Werner-Leopold Kepplinger, Rolf Hauk, Bogdan Vuletic, Felix Wallner, Walter-Rainer Kastner
  • Patent number: 5201940
    Abstract: The specification discloses a process for pre-heating and pre-reducing metal oxide ores. The process comprises introducing particles of an oxide ore entrained in a gas through a port into a treatment chamber. Inside the treatment chamber teh stream of entrained particles combines with a stream of high temperature reducing gas in such a way that the particles are heated rapidly and enter into flow patterns whereby contact with other particles and the internal surface of the treatment chamber is minimized. The stream of entrained particles and the stream of high temperature reducing gas are substantially co-current. A treatment chamber elongated in the direction of co-current flow is described in the specification. The hot off-gases may be derived from a molten bath reactor and comprise a high concentration of carbon monoxide and hydrogen.
    Type: Grant
    Filed: September 26, 1991
    Date of Patent: April 13, 1993
    Assignee: CRA Services Limited
    Inventors: Robin J. Batterham, Roderick M. Grant, James V. Happ, Glenn A. Thiele
  • Patent number: 5181955
    Abstract: The invention relates to a method and apparatus for raising the temperature and mixing efficiency of mainly non-combustible pulverous solid particles so high, that a desired smelting and volatilizing is achieved. The method is characterized in that the heating and mixing are carried out in at least two stages. Advantageously the reactions are made to happen in a suspension smelting furnace, such as a flash smelting furnace.
    Type: Grant
    Filed: January 27, 1992
    Date of Patent: January 26, 1993
    Assignee: Outokumpu Research Oy
    Inventors: Jussi A. Asteljoki, Jukka F. Laulumaa, Launo L. Lilja
  • Patent number: 5078787
    Abstract: A method and apparatus for the gaseous reduction of particulate iron ores, wherein the ore or is fed to a vertical moving bed direct reduction reactor, reduced therein, and discharged as hot sponge iron. The ore is charged to the top portion of the reduction zone of the furnace wherein the bed of particles which descend by gravity is reduced by a hot reducing gas largely composed by carbon monoxide and hydrogen. The hot reducing gas is divided in two portions, a first portion which flows upwardly through the reduction zone to reduce the ores therein, and a second portion which flows downwardly through a lower discharge zone to maintain the bed at a suitable temperature level. Finally, the product sponge iron is discharged from the bottom portion of the discharge zone of the furnace and conveyed, for example, to be melted in an electric arc furnace or to be briquetted in a briquetting machine coupled to the reduction reactor.
    Type: Grant
    Filed: June 1, 1990
    Date of Patent: January 7, 1992
    Assignee: Hylsa S.A. de C.V.
    Inventors: Jorge O. Becerra-Novoa, Fernando R. Webb-Balderas, Federico E. Carranza-Almaguer
  • Patent number: 4995906
    Abstract: A method for smelting reduction of iron ore, comprises the steps of: introducing iron ore into a preheat and prereduction furnace and preheating and prereducing the iron ore, a prereduction degree being less than 30%; charging the iron ore, carbonaceous material and flux into a smelting reduction furnace; blowing oxygen gas, through decarburization nozzles and post-combustion nozzles placed in a top end of an oxygen lance, into the smelting reduction furnace, the top end of the oxygen lance being located so as to be between a top level and a bottom level of a slag layer; blowing a stirring gas through side tuyeres placed in a side wall and bottom tuyeres placed in a bottom wall of the smelting reduction furnace; and controlling a flow amount of the oxygen gas and the stirring gas so that an oxidation degree of an exhaust gas generated in the smelting reduction furnace ranges 0.4 to 0.9 and still a temperature of the exhaust gas ranges 300.degree. to 1300.degree. C.
    Type: Grant
    Filed: December 12, 1988
    Date of Patent: February 26, 1991
    Assignee: NKK Corporation
    Inventors: Katsuhiro Iwasaki, Kenji Takahashi, Shigeru Inoue, Haruyoshi Tanabe, Masahiro Kawakami, Osamu Terada
  • Patent number: 4978106
    Abstract: A method and apparatus for reducing iron in a steelmaking process including a closed thermal transfer system in which a flow of process ingredients including iron ore is directed in a descending, preferably spiral path defined by a downwardly spiraling pipe with the process ingredients moving in countercurrent flow relation to a continuous flow of reducing gases ascending within the pipe to reduce the process ingredients to a continuously flowing stream of molten iron and slag which moves downwardly in the spiral pipe and into a hearth furnace.
    Type: Grant
    Filed: July 27, 1989
    Date of Patent: December 18, 1990
    Inventor: John J. Kelmar