From Electrolytic Or Cementation Slime Patents (Class 75/714)
  • Patent number: 11145915
    Abstract: The present invention provides a method for treating at least one lithium ion battery enclosed in a housing containing aluminum, comprising heating the lithium ion battery using a combustion furnace in which a combustion object is incinerated by flames, while preventing the flames from being directly applied to the housing of the lithium ion battery.
    Type: Grant
    Filed: December 30, 2019
    Date of Patent: October 12, 2021
    Assignee: JX NIPPON MINING & METALS CORPORATION
    Inventors: Shojiro Usui, Nobuaki Okajima
  • Patent number: 10727546
    Abstract: The present invention provides a method for treating at least one lithium ion battery enclosed in a housing containing aluminum, comprising heating the lithium ion battery using a combustion furnace in which a combustion object is incinerated by flames, while preventing the flames from being directly applied to the housing of the lithium ion battery.
    Type: Grant
    Filed: April 15, 2016
    Date of Patent: July 28, 2020
    Assignee: JX NIPPON MINING & METALS CORPORATION
    Inventors: Shojiro Usui, Nobuaki Okajima
  • Patent number: 10036080
    Abstract: The present disclosure relates to a metal recovery process comprising a solvent extraction process. In an exemplary embodiment, the solution extraction system comprises a plant with a first and second circuit. A high-grade pregnant leach solution (“HGPLS”) is provided to the first and second circuit, and a low-grade pregnant leach solution (“LGPLS”) is provided to the second circuit. The first circuit produces a rich electrolyte, which can be forwarded to a primary metal recovery, and a low-grade raffinate, which can be forwarded to a secondary metal recovery process. The second circuit produces a rich electrolyte, which can also be forwarded to the primary metal recovery process. The first and second circuits are in fluid communication with each other.
    Type: Grant
    Filed: October 22, 2015
    Date of Patent: July 31, 2018
    Assignee: FREEPORT MINERALS CORPORATION
    Inventors: Jason M Morgan, Barbara J Savage, David G Meadows, Wayne W Hazen
  • Patent number: 9181112
    Abstract: A method and an apparatus for treating coal gasification wastewater containing selenium and ions of a metal nobler than titanium eluted from a noble metal catalyst in a catalytic wet oxidation treatment using the noble metal catalyst, the method includes a pretreatment process removing the ions of the metal nobler than titanium and a selenium reduction process contacting the coal gasification wastewater with a mixture of metallic titanium and a simple metal baser than metallic titanium whereby a portion of the simple metal baser than metallic titanium is eluted, and the selenium in the coal gasification wastewater becomes reduced.
    Type: Grant
    Filed: May 30, 2012
    Date of Patent: November 10, 2015
    Assignee: KURITA WATER INDUSTRIES LTD.
    Inventors: Hiroyuki Asada, Yoshikazu Yatsu
  • Publication number: 20130152741
    Abstract: The present disclosure relates to a metal recovery process comprising a solvent extraction process. In an exemplary embodiment, the solution extraction system comprises a plant with a first and second circuit. A high-grade pregnant leach solution (“HGPLS”) is provided to the first and second circuit, and a low-grade pregnant leach solution (“LGPLS”) is provided to the second circuit. The first circuit produces a rich electrolyte, which can be forwarded to a primary metal recovery, and a low-grade raffinate, which can be forwarded to a secondary metal recovery process. The second circuit produces a rich electrolyte, which can also be forwarded to the primary metal recovery process. The first and second circuits are in fluid communication with each other.
    Type: Application
    Filed: December 20, 2011
    Publication date: June 20, 2013
    Applicant: FREEPORT-MCMORAN CORPORATION
    Inventors: Jason M. Morgan, Barbara J. Savage, David G. Meadows, Wayne W. Hazen
  • Publication number: 20130139649
    Abstract: The present invention relates to chelating resins containing methyleneaminoethylsulfonic acid groups, a process for producing them and also their use for removing heavy metals or metals of value from aqueous solutions having a pH of <4, preferably from process water in or from the electronics industry, the electroplating industry or the mining industry.
    Type: Application
    Filed: December 2, 2010
    Publication date: June 6, 2013
    Applicant: LANXESS Deutschland GmbH
    Inventors: Michael Schelhaas, Pierre Vanhoorne, Reinhold Klipper, Georg Martin
  • Patent number: 8323376
    Abstract: The present invention describes a method of recycling lead from lead containing waste, the method comprising the steps of mixing the battery paste with aqueous citric acid solution so as to generate lead citrate; isolating lead citrate from the aqueous solution; and converting the lead citrate to lead and/or lead oxide.
    Type: Grant
    Filed: November 6, 2007
    Date of Patent: December 4, 2012
    Assignee: Cambridge Enterprise Limited
    Inventors: Ramachandran Vasant Kumar, Vega Petrova Kotzeva, Seref Sonmez
  • Publication number: 20120067169
    Abstract: A method is disclosed for recovering precious metals from source materials containing precious metals which involves leaching the source material in aqueous reducing liquor to provide a treated solid residue and processing the treated residue to recover precious metals.
    Type: Application
    Filed: April 23, 2010
    Publication date: March 22, 2012
    Applicant: PRECIOUS METALS RECOVERY PTY LTD
    Inventor: Dean R. Butler
  • Publication number: 20100294082
    Abstract: Proposed is a method for collecting valuable metal from an ITO scrap including a step of collecting tin by subjecting the ITO scrap to electrolysis. Further proposed is a method for collecting valuable metal from an ITO scrap including the steps of providing an ITO electrolytic bath and a tin collecting bath, dissolving the ITO scrap in the electrolytic bath, and thereafter collecting tin in the tin collecting bath. Additionally proposed is a method for collecting valuable metal from an ITO scrap including the steps of dissolving the ITO scrap by subjecting it to electrolysis as an anode in electrolyte, precipitating only tin contained in the solution as tin itself or a substance containing tin, extracting the precipitate, placing it in a collecting bath, re-dissolving this to obtain a solution of tin hydroxide, and performing electrolysis or neutralization thereto in order to collect tin.
    Type: Application
    Filed: June 27, 2007
    Publication date: November 25, 2010
    Applicant: NIPPON MINING & METALS CO., LTD.
    Inventors: Yuichiro Shindo, Kouichi Takemoto
  • Patent number: 7815709
    Abstract: An electro-hydrometallurgical process that extracts zinc from electric furnace dust (EAF dust) to produce zinc of high purity and fine particle size, including leaching EAF dust with an alkaline solution to form a zincates solution, separating the liquid and gangue in the zincate solution; inertizing the gangue, purifying the liquid by cementation and separating the liquid from precipitated solids; purifying the zincate solution obtained from the cementation by adsorption, at least partially evaporating the resulting pure solution, bleeding at least a fraction of the concentrated solution obtained; crystallizing at least a fraction of the concentrated solution, electro-depositing zinc from the concentrated solution; and separating washing and drying deposited Zn.
    Type: Grant
    Filed: November 10, 2006
    Date of Patent: October 19, 2010
    Assignees: Tecnologias de Reciclaje S.A., Duberlis Correa Pena Y Lillo
    Inventors: Duberlis Correa Peña y Lillo, Ricardo Vega Viveros
  • Patent number: 7731777
    Abstract: The invention relates to a hydrometallurgical method for separating the precious metals and impurities of anode sludge obtained from copper electrolysis. According to the method, anode sludge copper is separated in atmospheric leaching; calcinated in two steps for separating selenium and for sulfatizing silver; the sulfatized silver is separated by leaching into a neutral aqueous solution, from which it can be separated by reduction or by extraction.
    Type: Grant
    Filed: August 31, 2004
    Date of Patent: June 8, 2010
    Assignee: Outotec Oyj
    Inventors: Leo Lindroos, Henri Virtanen, Olli Järvinen
  • Patent number: 7670575
    Abstract: The method and furnace according to the invention enable a continuous processing of anode slime and are particularly suited to be connected to a process where anode slime is treated by hydrometallurgic methods after roasting. In the method according to the invention, the slime containing valuable metals and selenium is dried, roasted, sulfatized and cooled. The method includes steps to be carried out in succession, in continuous operation, so that the slime forms a slime layer on the conveyor and is conveyed to be treated in successive drying, roasting, sulfatizing and sulfuric acid removal and cooling units.
    Type: Grant
    Filed: July 5, 2005
    Date of Patent: March 2, 2010
    Assignee: Outotec Oyj
    Inventors: Olli Järvinen, Pekka Taskinen, Olli Hyvärinen, Henri Virtanen, Leo Lindroos
  • Patent number: 7594951
    Abstract: A method for extracting and concentrating copper values from copper-I leach liquors that are economically non-viable using conventional SX-EW or known conventional configurations of IX. The novel process scheme is compatible and advantageous for use with a multi-port valve CIX system, a suitable membrane separation system and a selective scrubbing technique to control iron.
    Type: Grant
    Filed: December 7, 2005
    Date of Patent: September 29, 2009
    Inventor: Gordon Rossiter
  • Patent number: 7138005
    Abstract: The present invention provides a nickel refining method which uses nickel sulfide produced from nickel oxide ore using a hydrometallurgical process, as the raw material, and in which chlorine leaching is performed using a chloride solution, wherein a cementation reaction is caused between the nickel sulfide and copper ions, using copper ions, preferably included in the leaching solution itself, and a portion of the nickel in the nickel sulfide is leached into the solution, and the remaining nickel and copper are left as a residue, and copper and nickel are chlorine leached from this residue, and wherein the cementation reaction is performed with an oxidation-reduction potential as measured by a silver-silver chloride electrode of below ?20 mV, preferably below ?100 mV.
    Type: Grant
    Filed: September 9, 2002
    Date of Patent: November 21, 2006
    Assignee: Sumitomo Metal Mining Co., Ltd.
    Inventors: Keiji Kudo, Masaki Imamura, Kouji Ando
  • Patent number: 7018593
    Abstract: A method of recovering base metal from a tailings dump which includes the steps of: aerating a surface layer of the dump; adjusting the pH and the moisture content of the surface layer to provide conditions favourable for bacterial oxidation of sulphide minerals; allowing bacterial oxidation to take place for a controlled period, after the controlled period removing the oxidized surface layer and adding water thereto for form a slurry; separating the slurry into solids and a solution; and recovering base metal from the solution.
    Type: Grant
    Filed: August 31, 2000
    Date of Patent: March 28, 2006
    Assignee: Billiton SA Limited
    Inventors: Peter Michael Craven, Trevor Hugh Tunley
  • Patent number: 6800111
    Abstract: A method for recovering catalytic metals from compositions containing catalytic metal colloids. Compositions such as rinse solutions or dragout baths containing catalytic metal colloids are passed through a filter that entraps catalytic metal colloids from the solutions. The catalytic metal colloid has a high affinity for the filter in contrast to other components of the solutions. The other components of the solution pass through the filter concentrating the catalytic colloid on the filter. The filter containing the catalytic metal colloid is rinsed with an acid solution to remove the catalytic metal from the filter. The catalytic metal is collected in a suitable container or on an adsorbent such as a resin. The method is economically efficient and environmentally friendly.
    Type: Grant
    Filed: January 18, 2002
    Date of Patent: October 5, 2004
    Assignee: Shipley Company, L.L.C.
    Inventors: Jeffrey Doubrava, Eric C. Lundquist, James C. Bohling
  • Patent number: 6797033
    Abstract: A method for recovering catalytic metals from fluids containing catalytic metal colloids. Fluid compositions such as rinse solutions or dragout baths containing catalytic metal colloids are passed through a filter that entraps catalytic metal colloids on the filter. The catalytic metal colloids have a high affinity for the filter in contrast to other components of the fluids. The other components of the fluids pass through the filter while the catalytic colloids concentrate on the filter. The filter containing the catalytic metal colloids is burned, and the catalytic metal is retrieved. The method is economically efficient and environmentally friendly.
    Type: Grant
    Filed: November 21, 2002
    Date of Patent: September 28, 2004
    Assignee: Shipley Company, L.L.C.
    Inventors: Jeffrey Doubrava, Anthony Gallegos, Eric G. Lundquist, James C. Bohling, Richard F. Staniunas, Chad Serell
  • Patent number: 6773485
    Abstract: A method for recovering catalytic metals from fluid compositions containing catalytic metal colloids. Fluid compositions such as aqueous rinse solutions or dragout baths containing catalytic metal colloids are passed through a porous metal filter that entraps the catalytic metal colloids. The catalytic metal colloids have a high affinity for the porous metal filter in contrast to other components of the fluids. The other components of the fluids pass through the porous metal filter while the catalytic metal colloids concentrate on the porous metal filter. The catalytic metal colloids that are captured on the porous metal filter are removed from the filter by backwashing the filter with a gas and/or a liquid. The backwashing forces the catalytic metal colloids off of the porous metal filter and through a solids discharge valve and into a solids collection container. The method is economically efficient with high catalytic metal recovery and is environmentally friendly.
    Type: Grant
    Filed: November 21, 2002
    Date of Patent: August 10, 2004
    Assignee: Shipley Company, L.L.C.
    Inventors: Jeffrey Doubrava, Anthony Gallegos, Eric G. Lundquist, James C. Bohling, Richard F. Staniunas
  • Publication number: 20040118248
    Abstract: A method to dissolve at least one metal from jarosite or other iron hydroxyl sulphate containing-material which includes the steps of subjecting the material to alkaline treatment in a brine solution to facilitate jarosite decomposition, and acidification of the brine slurry to solubilise the liberated metal.
    Type: Application
    Filed: September 8, 2003
    Publication date: June 24, 2004
    Inventors: Noelene Ahern, Jozef Maria Schaekers
  • Publication number: 20040025638
    Abstract: The invention provides methods of using concentrated zinc chloride to protect zinc powders formed by electrowinning from oxidation during collection and removal from an electrowinning cell, during periods of prolonged storage and during melting. The invention provides a means of flushing zinc powders from all surfaces of an electrowinning cell and transporting and storing the zinc powders under a concentrated zinc chloride solution. The same concentrated solution can be used with ammonium chloride in a flux solution to melt the zinc powders prior to shaping the molten zinc into briquettes, pellets and the like.
    Type: Application
    Filed: January 17, 2003
    Publication date: February 12, 2004
    Inventor: Boris N. Slutskiy
  • Publication number: 20030066389
    Abstract: The present invention provides a nickel refining method which uses nickel sulfide produced from nickel oxide ore using a hydrometallurgical process, as the raw material, and in which chlorine leaching is performed using a chloride solution, wherein a cementation reaction is caused between the nickel sulfide and copper ions, using copper ions, preferably included in the leaching solution itself, and a portion of the nickel in the nickel sulfide is leached into the solution, and the remaining nickel and copper are left as a residue, and copper and nickel are chlorine leached from this residue, and wherein the cementation reaction is performed with an oxidation-reduction potential as measured by a silver-silver chloride electrode of below −20 mV, preferably below −100 mV.
    Type: Application
    Filed: September 9, 2002
    Publication date: April 10, 2003
    Inventors: Keiji Kudo, Masaki Imamura, Kouji Ando
  • Publication number: 20030015065
    Abstract: In one aspect, the present invention provides a method for recovering precious metal, and particularly gold, from a particulate substrate loaded with a precious metal-containing coating, in which a portion, but less than substantially all, of the particulate substrate is dissolved away to physically release precious metal-containing coating from the particulate substrate. The particulate substrate loaded with a precious metal-containing coating may be prepared during precious metal recovery operations by cementation of precious metal on a base metal particulate substrate from a pregnant leach solution, such as a leach solution including a thiosulfate lixiviant for the precious metal.
    Type: Application
    Filed: March 29, 2001
    Publication date: January 23, 2003
    Inventor: Rong Yu Wan
  • Publication number: 20020124691
    Abstract: A process comprises a separating process to mechanically separate refuse secondary batteries and to separate them into a separated cathode material and a separated anode material, and a process to recover valent metals from the separated anode and the separated cathode material separated in the separating process is disclosed.
    Type: Application
    Filed: March 4, 2002
    Publication date: September 12, 2002
    Applicant: MITSUI MINING & SMELTING CO., LTD.
    Inventors: Hironori Tateiwa, Minoru Kahata, Hiroshi Miyagawa, Ryoichi Shirai
  • Publication number: 20020020252
    Abstract: Process and equipment for the removal of crud from the interface between aqueous and organic layers in SX settlers in which at least one rotatable auger is positioned at or near the interface to remove crud continuously or intermittently from the interface.
    Type: Application
    Filed: July 18, 2001
    Publication date: February 21, 2002
    Inventors: Jerome P. Dorlac, R. Brantly Sudderth
  • Patent number: 6129779
    Abstract: A method for reclaiming a metallic material from a article including a non-metallic friable substrate. The method comprising crushing the article into a plurality of pieces. An acidic solution capable of dissolving the metallic material is provided dissolving the metallic material in the acidic material to form an etchant effluent. The etchant effluent is separated from the friable substrate. A precipitation agent, capable of precipitating the metallic material, is added to the etchant effluent to precipitate out the metallic material from the etchant effluent. The metallic material is then recovered.
    Type: Grant
    Filed: May 12, 1998
    Date of Patent: October 10, 2000
    Assignee: First Solar, LLC
    Inventors: John Raphael Bohland, Igor Ivanovich Anisimov, Todd James Dapkus, Richard Anthony Sasala, Ken Alan Smigielski, Kristin Danielle Kamm
  • Patent number: 6126720
    Abstract: A method for refining noble metals has a silver treating process including a nitric acid leaching step of silver, a purification step of the leaching solution, an electrolytic decomposition step of silver, and a recycling step after the electrolytic decomposition, wherein in the purification step, lime is added in order to precipitate the metallic impurities, such as selenium, tellurium, bismuth, and copper, by neutralization of the leaching solution, and in the recycling step, sulfuric acid is added to the solution after electrolytic decomposition to regenerate nitric acid for recycling use by precipitation of calcium in the solution as gypsum. Preferably, the refining method has a gold recovery process, as well as the silver treating process, wherein the residue of the nitric leaching of the crude silver is dissolved by chlorination and gold is recovered from the leaching solution by solvent extraction or reductive precipitation.
    Type: Grant
    Filed: January 15, 1999
    Date of Patent: October 3, 2000
    Assignee: Mitsubishi Materials Corporation
    Inventors: Satoshi Okada, Hiromi Mochida
  • Patent number: 6051049
    Abstract: Novel utilizations of strontium aluminate, a by-product of the manufacture of strontium, are disclosed in connection with the art of steelmaking. It is useful as a synthetic slag covering for molten iron or steel, as well as in the foaming slag practice, as a backfilling material for spaces between the safety lining and the working lining of a ladle, as a major component for a blend from which are made pellets or briquettes useful as a slag conditioner, as an additive to calcium aluminate which has the effect of substantially lowering the melting point of calcium aluminate, as a tracer material to determine the source of impurities, and as a binder to recycle metal-containing dust.
    Type: Grant
    Filed: May 27, 1998
    Date of Patent: April 18, 2000
    Assignee: Exothermic Distribution Corporation
    Inventor: Pierre Vayda
  • Patent number: 5632963
    Abstract: A process is disclosed for removing impurity elements, such as arsenic, and if necessary antimony, iron or bismuth, from valuable metal containing, such as copper containing, strongly mineral acid solutions by way of solvent extraction with organic solutions of hydroxamic acids, and for selectively stripping the impurity elements therefrom. Antimony, iron or bismuth are stripped with complexing acids, and arsenic is stripped with an aqueous solution containing valuable metal ions at a pH value in the 1.5 to 5 range, a higher pH than the original valuable metal containing aqueous acid solution.
    Type: Grant
    Filed: October 19, 1994
    Date of Patent: May 27, 1997
    Assignee: Henkel Kommanditgesellschaft auf Aktien
    Inventors: Werner Schwab, Ralf Kehl
  • Patent number: 5478664
    Abstract: A method of recovering a reusable metal from a nickel-hydrogen rechargeable battery characterized in that the method comprises crushing the nickel-hydrogen rechargeable battery to obtain a crushed material, separating alkali, organic substances and iron from the crushed material to obtain a separated component from which at least the alkali, organic substances and iron are separated, obtaining the reusable metal to be recovered as an oxide from the separated component by calcination, and processing the oxide by a molten salt electrolysis method with an electrolytic molten salt bath. According to this method for recovery, electrode materials effective for nickel-hydrogen rechargeable batteries and the like can be recovered efficiently and in a large amount in lower cost compared to the ordinary separation, purification and refining utilizing chemical processing.
    Type: Grant
    Filed: November 30, 1994
    Date of Patent: December 26, 1995
    Assignee: Santoku Metal Industry Co., Ltd.
    Inventors: Akihito Kaneko, Nobuyuki Kitazume, Chikara Okada
  • Patent number: 5462670
    Abstract: A process for removing dissolved oils and greases from an aqueous solution which also may contain dissolved heavy metals is provided wherein the aqueous solution is mixed with a source of ferrous ion and dithionite ion in a first step at acidic pH to reduce and permit removal of solid heavy metal, is present and to separate oils and greases from the aqueous solution. Solution from the first step if reacted in a second step with hydroxide slurries obtained from third and fourth steps. A second step solution from the second step is reacted in a third step with an alkali composition and a third solution. Optionally, the third solution is reacted with a chelating agent for iron and an oxidizer in a fourth step. A solution of chelated iron from the fourth step, when practical is disposed of. Oils and greases are recovered from the first step such as by skimming.
    Type: Grant
    Filed: March 28, 1994
    Date of Patent: October 31, 1995
    Assignee: Romar Technologies, Inc.
    Inventor: Robert G. Guess
  • Patent number: 5456992
    Abstract: Household sealed cell alkaline and zinc carbon batteries may be recycled for use in steel making as follows. The batteries are pulverized then run through an acidic bath to neutralize the alkaline electrolyte. Next the materials are rinsed, then dried and mixed with granulated carbon steel typically in a ratio of 5 parts battery material to 95 parts granulated carbon steel. The mixture is compressed into briquettes for introduction into steel making furnaces.
    Type: Grant
    Filed: October 20, 1994
    Date of Patent: October 10, 1995
    Inventor: Kenneth W. Elliott
  • Patent number: 5389262
    Abstract: Heavy metal ions react with ferrous dithionite in acidic aqueous solution. They are reduced to metallic particles that are suitable for recycling and reuse when recovered from the acidic water. Chelating agents that are present are deactivated by bonding to the ferrous ions. Ferrous dithionite, (FeS.sub.2 O.sub.4) is either generated in-situ or ferrous ions and dithionite ions can be provided by other methods. An alkali metal hydroxide is utilized to precipitate remaining heavy metal ions including ferrous and ferric ions.
    Type: Grant
    Filed: March 28, 1994
    Date of Patent: February 14, 1995
    Assignee: Romar Technologies, Inc.
    Inventor: Robert G. Guess
  • Patent number: 5298168
    Abstract: A process for removing dissolved heavy metal from an aqueous solution is provided where the aqueous solution is mixed with a source of ferrous ion and dithionite ion in a first step at acidic pH to reduce and permit removal of the heavy metal. Solution from the first step is reacted in a second step with hydroxide slurrys obtained from third and fourth steps. A second solution from the second step is reacted in a third step with an alkali composition and a third solution. The third solution is reacted with a chelating agent for iron and an oxidizer in a fourth step. A solution of chelated iron from the fourth step is disposed of.
    Type: Grant
    Filed: June 3, 1992
    Date of Patent: March 29, 1994
    Assignee: Romar Technologies, Inc.
    Inventor: Robert G. Guess
  • Patent number: 5271909
    Abstract: A method of increasing the extraction of tellurium from copper electrorefining slime comprises leaching the slime with dilute sulphuric acid in a reactor under a partial oxygen pressure of up to 150 psi and at an elevated temperature between about 100.degree. and 200.degree. C. until copper, nickel and substantially all of the tellurium is dissolved, thereby forming a leach slurry, and contacting the slurry with an appropriate reducing agent immediately after the leaching operation has been halted and the leaching reactor brough back to atmospheric pressure to reprecipitate any excessive quantities of silver and selenium solubilized during the leaching operation.
    Type: Grant
    Filed: July 9, 1992
    Date of Patent: December 21, 1993
    Assignee: Noranda, Inc.
    Inventors: Pierre L. Claessens, Carl W. White
  • Patent number: 5108721
    Abstract: A two-stage process for treating anode slimes and other residues containing a substantial amount of nickel without significant dissolution of silver and/or selenium in a single autoclave is disclosed. The process comprises, in a first stage, leaching the anode slimes at 15-30% solids in dilute sulphuric acid at a pressure between 4.0 and 5.5 bars and a temperature between 155.degree. C. to 170.degree. C. in the absence of oxygen to solubilize nickel, and in a second stage, without performing a solid liquid separation, leaching the remaining solids at a pressure between 2 and 3.5, preferably about 2.8 bars and a temperature between 110.degree. and 140.degree. C., preferably about 120.degree. C. with oxygen sparging such that the final sulphuric acid concentration is not less than 50 gpl to solubilize copper and tellurium.
    Type: Grant
    Filed: February 26, 1991
    Date of Patent: April 28, 1992
    Assignee: Noranda Inc.
    Inventors: Viken P. Baboudjian, Bernard H. Morrison, Jack S. Stafiej