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WO1995029779A1 - Traitement de granules de metal - Google Patents

Traitement de granules de metal Download PDF

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Publication number
WO1995029779A1
WO1995029779A1 PCT/GB1995/000991 GB9500991W WO9529779A1 WO 1995029779 A1 WO1995029779 A1 WO 1995029779A1 GB 9500991 W GB9500991 W GB 9500991W WO 9529779 A1 WO9529779 A1 WO 9529779A1
Authority
WO
WIPO (PCT)
Prior art keywords
granules
container
temperature range
primary
cooling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB1995/000991
Other languages
English (en)
Inventor
Cliff Samuel Treadwell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Holton Machinery Ltd
Original Assignee
Holton Machinery Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Holton Machinery Ltd filed Critical Holton Machinery Ltd
Priority to AU23167/95A priority Critical patent/AU2316795A/en
Publication of WO1995029779A1 publication Critical patent/WO1995029779A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • C22B1/00—Preliminary treatment of ores or scrap
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/145—Chemical treatment, e.g. passivation or decarburisation
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents

Definitions

  • One of the feedstocks for Conform-type continuous extrusion machines is granular metal pieces, chiefly of aluminium or copper. These granules are used in e.g. a conform machine to form extruded end-products such as wire, rod, bar or special shaped sections.
  • a granular feedstock material of acceptable purity In order to optimise the quality of the extruded end- products, it is desirable to use a granular feedstock material of acceptable purity.
  • Typical contaminants, particularly for copper granules, include organic components like PVC and polyethylene sheathing from wire insulation. It is also desirable to minimise or avoid metal oxide impurities in the granules which can affect mechanical performance of extruded end-products.
  • Electrical wire comprising copper conductor, which has been used for various applications is eventually discarded. Because the copper can be retrieved, there is interest in recycling the material, to produce recycled copper wire for re-use. Generally the wire is granulated but there may be up to about 1% by weight of plastics insulation material remaining as contaminants.
  • the present invention seeks to provide a method and apparatus for treating metal granules, and more particularly a method and apparatus for thermal treatment to remove contaminants from metal granules such as copper granules.
  • the invention also seeks to provide such apparatus and method which can operate to reduce or minimise oxide impurities and thereby achieve a desirably low content of oxygen in the granules, for example no higher than 600 ppm of oxygen in the treated copper or aluminium granules but preferably less than 400 ppm, and even more preferably less than 300 ppm of oxygen in the treated granules, such as 250 ppm or below.
  • the present invention in both its aspects is based on vaporising organic contaminants, recrystallising and annealing of the metal granules, minimising oxidation during vaporisation, recrystallisation and annealing, and using an atmosphere which can be non-oxidising or reducing in nature to control i.e. minimise formation of metal oxide.
  • a method of removing contaminants from granular metal feedstock by heat treatment thereof and subsequent cooling within a gaseous atmosphere which is non-oxidising or reducing and which method comprises:
  • the granules can be acid treated to remove any metal oxidation which may have occurred before use, also organic and inorganic residues from any plastic contamination on the granules can be removed by such acid treatment.
  • This may be effected by immersion in a weak acid e.g. immersing treated granules in a weak acid bath for 1-5 mins, washing with water if required and drying if required.
  • the invention provides apparatus for removing contaminants from granular metal feedstock which is constructed to apply heat treatment to said granules and subsequent cooling thereof within an atmosphere comprising inert or other non-oxidising gas and/or reducing gas which comprises:
  • a secondary heating means also extending over at least part of said container wherein the granules which have been heated by said primary heating means can be maintained within or near said primary temperature range or can be further heated to a temperature within a secondary temperature range
  • atmospheric control means arranged to maintain an atmosphere within the container and in any extension thereof if present within the region of said cooling means, which comprises inert or other non-oxidising gas and/or reducing gas.
  • the apparatus may include an acid bath containing a weak acid solution to be located in the vicinity of the means (f) for discharging treated granules.
  • the primary temperature range may be 700°C ⁇ 300°C, more preferably ⁇ 200°C most preferably ⁇ 50°C.
  • the secondary temperature range may be 720°C ⁇ 300°C, more preferably ⁇ 200°C most preferably ⁇ 50°C.
  • the third temperature range may be below 100°C, preferably below 60°C, more preferably below 50°C, most preferably below 40°C for example 35°C or below.
  • the supply and feed of metal granules can be continuous in the apparatus and method.
  • Said contaminants preferably comprise plastics material which is capable of vaporisation within the primary and/or secondary heating means.
  • the feedstock may be aluminium or copper granules, preferably copper granules produced from cable and/or soudronic scrap.
  • an atmosphere which is at least mildly reducing by using a gaseous mixture as the atmosphere which comprises an inert or other non-oxidising gas, such as nitrogen, and a reducing gas such as hydrogen.
  • the mixture may comprise N 2 and H 2 in a volumetric ratio of the order 5N 2 : 1.5 H 2 - This can be achieved using controlled flow meters delivering N 2 and H 2 to the interior of the container (and of any extension part thereof in communication therewith) which is most desirably sealed against the ingress of external air.
  • the supply means can be a pulsed feed supply hopper terminating at a control valve which communicates via a conduit to the said container.
  • the container may be a hollow tube, cylinder or drum, having an internal helical thread and which drum or cylinder is rotated by a drive means to ensure that a supply of granules fed at an inlet end thereof is caused to travel along the length of that container, and if present of any extension part thereof.
  • Such drive means can be a belt-or chain-driven motor adapted to rotate the container continuously from 0.5 rpm to about 10 rpm, but preferably no higher than 2 rpm.
  • the container is preferably of corrosion resistant material such as nickel- chrome alloy.
  • An extension thereof may be connected by a suitable junction part at that end of the container remote from the supply inlet.
  • the granules may spend some 1- 20 preferably 2 - 15 minutes within the primary and second heating means.
  • the primary and secondary heating means may be a combined furnace which has a hollow internal region within which the container is mounted for rotation.
  • a furnace can be heated and controlled electrically, and the drive motor may be electrically operable and controlled for adjusting rotation speed of the container and hence duration of the granules within a given length of the container e.g. residence time within the primary heating means, secondary heating means and within the cooling means.
  • the cooling means may comprise a jacket having a hollow interior and encasing either a substantial part of the container or alternatively surrounding an extension part thereof. Coolant can be supplied and recycled to coolant spray means situated within the jacket above the said container part or an extension thereof. Coolant may collect, optionally for recycle, in a trough also within the jacket, beneath the container part which is to be cooled by the sprayed coolant.
  • Means for discharge may be a manifold located at that end of the container (of its extension) remote from the granule supply inlet. It may have a controllable rotary valve discharge outlet.
  • the gaseous atmosphere for the heating and cooling process may be provided by constructing a gaseous supply inlet, at the discharge end of the container (or of the extension) to feed in the appropriate non-oxidising and/or reducing atmosphere so as to purge the entire interior of the container and of any extension part of air before operation of the heating and cooling process.
  • Figure 1 is cross sectional view of metal granule treatment apparatus
  • Figure 2 is a side elevation of the section shown in Figure 1, viewed in the direction of the heating means.
  • a feed hopper 1 supply means has a funnel shaped inlet leading to a rotary control valve 2 which in turn communicates with a supply conduit 3 whose entry point 4 for supplying granules terminates within the inlet end of a hollow rotatable drum 6 having an internal continuous helical groove 7.
  • the drum 6 is in communication with an extension drum 9 of similar dimension and with a continuous internal helical groove 7 too.
  • a junction member 8 joins the container 6 to extension part 9 in a gas-tight manner and may provide support for the weight of the combined drum/extension at its location (although not shown) .
  • the hollow drum 6 is externally surrounded by an electric furnace defining a heating zone 10 and comprising both a primary heating means 11 (not shown separately) and a secondary heating means 12 (not shown separately) or a heat retaining means (not shown separately) .
  • the electric furnace has a hollow interior (see Figure 2 particularly) and the container 6 is located within that hollow interior and mounted for rotation although drive means to initiate and maintain rotation are not illustrated.
  • a cooling zone 13 Spaced from one end of the furnace is a cooling zone 13 comprising a metal tank 14, coolant feed pipe 15, coolant sprays 16 adapted to spray coolant such as water from a trough 17 comprising a recyclable supply of coolant liquid.
  • the tank 14 is also hollow and the extension part 9 of the container is free to rotate therein without contacting the tank.
  • a granule collection manifold 19 is provided with a gas-tight seal for collecting the heat treated and subsequently cooled metal granules.
  • the manifold 18 has a controllable rotary outlet valve 20 leading to a discharge or final granule collection point 21 at the end of the entire apparatus remote from the granule supply means 1,2,3.
  • Granules can be collected here or fed directly into conform- type extrusion apparatus, or to 9 specially designed feed system for granules to undergo other contaminant removal steps e.g. removal of metallic contaminants.
  • Rotation of the drum 6 causes the extension 9 to rotate and granules thereby travel along the internal path of the drum and the extension during which travel they are subjected to the heating and cooling steps in the presence of an inert or of a reducing atmosphere.
  • the furnace defining the heating zone 10 is designed to heat treat 1000 kg/hr of granulated Soudronic/Cable scrap at a temperature of 700°C over a cycle of 2 - 5 mins. Electrical Rating: 150 kW total 2 zones. 415 - 3 - 50 Hz.
  • Heating Zone Heat treatment is carried out in an electrically heated drum.
  • the drum is fabricated from heat resistant steel with an internal helix cut into the internal wall.
  • the heating chamber is lined with ceramic fibre of sufficient thickness to give a cold face temperature of 50°C.
  • Heating is by use of silicon carbide heating elements. The elements being arranged in two zones, namely a primary heating means which is a preheat zone with high input to give a rapid heat-up period, and a secondary heating means in the form of a soak zone with lower input to maintain the charge at its treatment temperature.
  • Three phase multi-tapped transformers are fitted to control the elements.
  • the pre-heat and soak zones are temperature controlled with separate policemen over temperature controllers.
  • the cooling zone supplies cooled granules from an extension of the heating drum also with a co ⁇ operating internal helix cut into the internal wall.
  • the cooling drum is fabricated from a corrosion resisting stainless steel. Cooling is assisted by the water sprays situated above the extension.
  • the extension is encased by a steel jacket-like enclosure with a stainless steel tank in the base to collect the cooling water. The water is circulated using an integrated pumping system. The water could pass through a heat exchanger.
  • the drum is driven by a chain and sprocket arrangement via a gearbox and variable speed motor.
  • Charging The charge is introduced to the furnace by a rotary valve.
  • the valve is fitted with an adjustable vent type metering baffle to control the charge rate.
  • the drive is speed controlled for close control of the charge rate.
  • the valve is fitted with a stainless steel rotor and blade.
  • Discharging Discharging is carried out through a rotary valve which operates at a fixed speed.
  • Atmosphere A non-oxidising and reducing atmosphere comprising a gaseous mixture of nitrogen and hydrogen atmosphere is used. This is controlled from a panel, containing flow meters, flow control valves and all necessary controls and mixing arrangements (not shown) .
  • a flow alarm controller is fitted with two alarms for high and low flows. The control system is arranged so that nitrogen is introduced before hydrogen, and in the event of a leak developing in the atmosphere supply line (not shown) , the hydrogen is shut down. The atmosphere ratio is altered to suit the charge.
  • Control The furnace is controlled by a personal computer linked to all variable parameters such as temperature, cooling systems, drum rotation etc., to give standard operating conditions. All controls can be conveniently installed in a suitable panel and prewired.
  • an acid immersion bath can be located adjacent the outlet 21 for acid immersion of the cooled granules, and washing/drying before use in e.g. a conform extrusion machine.
  • the table below shows the results obtained from granulating and thermally treating copper cable scrap under varying conditions of cleanliness and usage of atmospheric gas control.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

Appareil destiné à enlever des contaminants d'une charge d'alimentation de métal granulaire et construit pour appliquer aux granules un traitement thermique suivi d'un traitement de refroidissement, dans une atmosphère comprenant un gaz inerte ou non oxydant et/ou un gaz réducteur, ledit appareil comprenant: (a) des moyens d'alimentation (1), (b) un contenant (6) généralement creux, (c) des premiers moyens (11) de chauffage, (d) des second moyens (12) de chauffage, (e) des moyens (13) de refroidissement, (f) des moyens (18) conçus pour décharger du contenant ou de l'extension de celui-ci les granules refroidis, et (g) des moyens de régulation atmosphérique conçus de manière à maintenir une certaine atmosphère à l'intérieur du contenant. On décrit également un procédé de traitement de granules consistant à enlever des contaminants tels qu'une enveloppe de plastique, tout en maintenant dans les granules une teneur volontairement faible en oxygène.
PCT/GB1995/000991 1994-04-29 1995-05-01 Traitement de granules de metal Ceased WO1995029779A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU23167/95A AU2316795A (en) 1994-04-29 1995-05-01 Treatment of metal granules

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9408585.9 1994-04-29
GB9408585A GB9408585D0 (en) 1994-04-29 1994-04-29 Treatment of metal granules

Publications (1)

Publication Number Publication Date
WO1995029779A1 true WO1995029779A1 (fr) 1995-11-09

Family

ID=10754366

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/000991 Ceased WO1995029779A1 (fr) 1994-04-29 1995-05-01 Traitement de granules de metal

Country Status (3)

Country Link
AU (1) AU2316795A (fr)
GB (1) GB9408585D0 (fr)
WO (1) WO1995029779A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003052166A1 (fr) * 2001-12-17 2003-06-26 Elino Industrie-Ofenbau Carl Hanf Gmbh & Co. Procede et dispositif permettant d'enlever les adherences, notamment les adherences huileuses ou grasses, de la surface de pieces metalliques
CN102534221A (zh) * 2011-12-31 2012-07-04 阙龙翔 一种高温真空充氮循环烧冶的杂铜回收工艺

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2489116A (en) * 1946-05-03 1949-11-22 Sk Wellman Co Method of treating metallic powders
GB1046395A (en) * 1963-04-29 1966-10-26 Int Alloys Ltd Recovery of metals
US3404000A (en) * 1966-07-19 1968-10-01 British Insulated Callenders Process for the production of copper bodies of high mechanical strength and high electrical conductivity
WO1992005001A1 (fr) * 1990-09-20 1992-04-02 Mannesmann Ag Procede et installation de recuit de fer en poudre par reduction

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2489116A (en) * 1946-05-03 1949-11-22 Sk Wellman Co Method of treating metallic powders
GB1046395A (en) * 1963-04-29 1966-10-26 Int Alloys Ltd Recovery of metals
US3404000A (en) * 1966-07-19 1968-10-01 British Insulated Callenders Process for the production of copper bodies of high mechanical strength and high electrical conductivity
WO1992005001A1 (fr) * 1990-09-20 1992-04-02 Mannesmann Ag Procede et installation de recuit de fer en poudre par reduction

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003052166A1 (fr) * 2001-12-17 2003-06-26 Elino Industrie-Ofenbau Carl Hanf Gmbh & Co. Procede et dispositif permettant d'enlever les adherences, notamment les adherences huileuses ou grasses, de la surface de pieces metalliques
CN102534221A (zh) * 2011-12-31 2012-07-04 阙龙翔 一种高温真空充氮循环烧冶的杂铜回收工艺

Also Published As

Publication number Publication date
AU2316795A (en) 1995-11-29
GB9408585D0 (en) 1994-06-22

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