Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/001—Dry processes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/90—Carbides
  • C01B32/914—Carbides of single elements
  • C01B32/949—Tungsten or molybdenum carbides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B34/00—Obtaining refractory metals
  • C22B34/30—Obtaining chromium, molybdenum or tungsten
  • C22B34/36—Obtaining tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F2009/001—Making metallic powder or suspensions thereof from scrap particles
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present disclosure belongs to the recycling of a metal alloy.
• the disclosure relates to a method of recycling of tungsten carbide alloy.
• the method is cost effective and environment friendly in nature.
• the scraps are also recycled by zinc process which yields the tungsten carbide powder directly. But this is a costly process and requires huge investment. Other processes like leach milling, acid leaching and electrolysis. Inspite of the availability of various methods about 35% of the scraps are not recycled for want of capacity.
• the present disclosure provides a process for recycling of tungsten carbide alloy comprising acts of oxidizing the tungsten carbide alloy to obtain tungsten oxide and other metallic oxides, grinding the tungsten oxide and other metallic oxides to obtain a powder and treating the powder with a carburizing gaseous mixture for reducing and carburizing the tungsten oxide and other metallic oxide powder to obtain the purified tungsten carbide alloy powder.
• FIG. 1 illustrates the process of recycling of tungsten carbide alloy in a flowchart.
• Figure 2 is the micro structure of the recycled powder from example 1 analyzed by EDS method.
• Figure 3 is the graph showing the quantity of electrons diffracted by the particular element during EDS studies from the powder recycled from example 1.
• Figure 4 is the micro structure of the recycled powder from example 2 analyzed by EDS method.
• Figure 5 is the graph showing the quantity of electrons diffracted by the particular element during EDS studies from the powder recycled from example 2.
• Figure 6 is the micro structure of the recycled powder from example 3 analyzed by EDS method.
• Figure 7 is the graph showing the quantity of electrons diffracted by the particular element during EDS studies from the powder recycled from example 3. DESCRIPTION OF DISCLOSURE
• the present disclosure relates to a process for recycling of tungsten carbide alloy comprising acts of oxidizing the tungsten carbide alloy to obtain tungsten oxide and other metallic oxides, grinding the tungsten oxide and other metallic oxides to obtain a powder and treating the powder with a carburizing mixture for reducing and carburizing the tungsten oxide and other metallic oxide powder to obtain the purified tungsten carbide alloy powder.
• the oxidation is carried out in an oxidation furnace at a temperature ranging from about 400°C to about 1000°C, preferably at about 950°C.
• the oxidation is carried out using oxidizing agent selected from a group comprising air and oxygen preferably air.
• the grinding is carried out by a method selected from a group comprising ball mill, Attritor Mill, High Speed Intensive mill; preferably ball mill.
• the grinding is carried out for a period ranging from about 0.5 h to about lOh, preferably for about 2h.
• the carburizing mixture is selected from a group comprising hydrogen, nitrogen, carbon monoxide, methane, carbon dioxide, compressed natural gas (CNG), liquefied petroleum gas (LPG) and mixtures thereof
• the carburizing mixture is a combination of about 10% liquefied petroleum gas and about 90% nitrogen
• the treatment with the carburizing mixture is carried out for a period ranging from about lh to about 15h, preferably 3 h.
• the treatment with the carburizing mixture to obtain the purified tungsten carbide alloy powder is carried out in a reduction furnace at a temperature ranging from about 800°C to about 1400°C, preferably at about 1050°C .
• the purified tungsten carbide alloy powder is cooled to a temperature ranging from about 300 °C to about 200 °C preferably about 200 °C in nitrogen, and then to about 35 °C to about 25 °C, preferably about 25 °C in air.
• the tungsten carbide alloy includes such physically diverse items as tungsten carbide alloy scraps, spent and off-quality wires, turnings, grindings, worn out inserts, drill bits, cutters, die blocks and any other forms of worn out machine tools which possess tungsten carbide alloy. Accordingly, for purposes of the present disclosure, the term "tungsten carbide alloy" is intended to include, but not be limited to, any and all of the various forms mentioned above.
• recycling of tungsten carbide alloy includes recycling of tungsten carbide alloy, obtaining a pure form of tungsten carbide alloy powder from tungsten carbide alloy scraps. Accordingly, for purposes of the present disclosure, the term "recycling of tungsten carbide alloy" is intended to include, but not be limited to, any and all of the various forms mentioned above. In an embodiment of the present disclosure, when compared to other processes for the recycling of tungsten carbide alloy from the worn out inserts and rejected products, the present disclosure is a very cost effective solution which yields the quality at par with virgin powders.
• thermo mechanical treatment which will convert the tungsten carbide back into mix powder with exactly same chemical composition as the mix produced from virgin powders and with other qualitative parameters which is ready to be pressed back into inserts.
• the proposed process is a thermo mechanical process it does not generate any effluent.
• the proposed process uses, simpler & cheaper machines and operations hence the cost of recycling is greatly reduced.
• the disclosure involves the oxidation of tungsten carbide scraps at a suitable temperature to convert the alloy elements into their oxides. The oxides are ground to convert them into powders. The oxide powders are mixed with reducing agents like carburizing gas and are reduced at a suitable temperature and environment, to convert back into original alloy powder mix.
• the principle behind the disclosure is to convert the elements into their oxides which are very light and amenable to grinding.
• the oxide powders are then reduced to convert back into original elements.
• the carbon present in the tungsten carbide alloy as carbides will escape as carbon-di- oxide during oxidation. This problem will be addressed using carbothermic reduction.
• This process can produce a high quality powder mix at a very cheaper rate by which the requirement for scarce, costlier virgin powders can be substituted, since the process is not calling for any costlier equipments or consumables.
• tungsten oxide, cobalt- oxide and other metallic oxides are formed during oxidation.
• the broad range of percentage of carburizing gas in the hydrogen mixture is 0.7 % to 30%.
• the oxidizing agent present inside the furnace chamber is air.
• the final characterization of the tungsten carbide powder involves the following: 1. Chemical analysis to find out percentage of tungsten, carbon, Cobalt & Oxygen using Electron Diffraction Studies;
• Example 1 An embodiment of the present disclosure, is further illustrated by the following examples, which should not be construed to limit the scope of the disclosure in anyway.
• Example 1
• Figure 2 is the micro structure of the recycled powder from example 1 analyzed by EDS method.
• Figure 3 is the graph showing the quantity of electrons diffracted by the particular element from the recycled powder extracted from example 1.
• the table 2 shown below illustrates the results of the quantitative analysis of the recycled powder from experiment 1.
• Figure 4 is the micro structure of the recycled powder from example 2 analyzed by EDS method.
• Figure 5 is the graph showing the quantity of electrons diffracted by the particular element from the recycled powder extracted from example 2.
• the table 4 shown below illustrates the results of the quantitative analysis of the recycled powder from experiment 2.
• Figure 6 is the micro structure of the recycled powder from example 3 analyzed by EDS method.
• Figure 7 is the graph showing the quantity of electrons diffracted by the particular element from the powder extracted from example 3.
• the table 6 shown below illustrates the results of the quantitative analysis of the recycled powder from experiment 3.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Inorganic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2010
  • 2010-12-07 RU RU2012133072/02A patent/RU2012133072A/ru not_active Application Discontinuation
  • 2010-12-07 US US13/516,458 patent/US20120251416A1/en not_active Abandoned
  • 2010-12-07 EP EP10807378.4A patent/EP2521799A1/de not_active Withdrawn
  • 2010-12-07 KR KR20127020404A patent/KR20120106882A/ko not_active Application Discontinuation
  • 2010-12-07 WO PCT/IB2010/055620 patent/WO2011083376A1/en active Application Filing
  • 2010-12-07 CN CN2010800607743A patent/CN102725429A/zh active Pending

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