EP0628367A2 - Procédé pour la régénération de sable de fonderie usé - Google Patents

Procédé pour la régénération de sable de fonderie usé Download PDF

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Publication number
EP0628367A2
EP0628367A2 EP94108072A EP94108072A EP0628367A2 EP 0628367 A2 EP0628367 A2 EP 0628367A2 EP 94108072 A EP94108072 A EP 94108072A EP 94108072 A EP94108072 A EP 94108072A EP 0628367 A2 EP0628367 A2 EP 0628367A2
Authority
EP
European Patent Office
Prior art keywords
sand
grater
control modules
dedusting
dust
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.)
Granted
Application number
EP94108072A
Other languages
German (de)
English (en)
Other versions
EP0628367B1 (fr
EP0628367A3 (fr
Inventor
Norbert Ing. Damm
Thomas Dr.-Ing. Parr
Tao Dr.-Ing. Wang
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.)
Badische Maschinenfabrik GmbH
BMD Badische Maschinenfabrik Durlach GmbH
Original Assignee
Badische Maschinenfabrik GmbH
BMD Badische Maschinenfabrik Durlach GmbH
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 Badische Maschinenfabrik GmbH, BMD Badische Maschinenfabrik Durlach GmbH filed Critical Badische Maschinenfabrik GmbH
Publication of EP0628367A2 publication Critical patent/EP0628367A2/fr
Publication of EP0628367A3 publication Critical patent/EP0628367A3/fr
Application granted granted Critical
Publication of EP0628367B1 publication Critical patent/EP0628367B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
    • B22C5/18—Plants for preparing mould materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
    • B22C5/10—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by dust separating

Definitions

  • the invention relates to a method for regenerating foundry sands by feeding the used sand in batches to a grater for mechanically loosening the binder casing from the grain of sand, removing it from the grater by means of a conveying device, dedusting it and returning it to the grater and, if appropriate, removing it as regenerated sand after several cycles .
  • Thermal and mechanical processing methods are known for the regeneration of old foundry sands.
  • the thermal processes are particularly suitable for organic binders that are not thermally stable.
  • these processes require a large amount of energy and, on the other hand, lead to gas emissions, which requires additional effort in the removal of environmentally harmful gases.
  • mechanical friction and abrasion processes have been increasingly investigated, which anyway offer the only effective way of removing the binder shell from inorganic binders.
  • Combined methods have also been proposed to in particular to process old sand mixtures with different types of binders.
  • the object of the invention is to optimize the process mentioned at the outset for the mechanical reprocessing of foundry sands in order to maintain a consistently high level of efficiency in cleaning to obtain.
  • the invention is based initially on the knowledge that old foundry sands due to their very different composition (fine substance content, that from the still activatable bentonite, still burned bentonite (oolitized bentonite), coal dust, content of coke and chamotte, which mostly adhere to the grain of sand, and content on pure quartz) also a varying treatment during mechanical processing by rubbing and when separating the components by dusting.
  • the used sand drawn off from the grater is therefore conveyed into an intermediate vessel, in which the dedusting takes place, and the dedusted old sand is returned to the grater.
  • the amount circulated between the grater and the intermediate vessel also plays a role.
  • Another quality criterion of the used sand is its moisture, which plays a role especially in the case of clay (bentonite) bound molding sands.
  • This residual moisture present in the old sand interferes with the dedusting during sand preparation and influences the necessary addition of water during molding sand. Further the residual moisture and the sludge contained in the old sand form a kind of lubricant that affects the rubbing treatment in the grater.
  • the old sand is therefore first dried in a dryer, from there into the tundish and then circulated between it and the grater.
  • the used sand is freed of residual moisture in the dryer or dried to a defined low moisture content.
  • the process stage "drying" (T) is also included in the control modules M1 to M n , with a different percentage of the nominal power of the dryer. Not only the grater, the conveyor and the dedusting device, but also the dryer are then controlled with a sequence of control modules selected in accordance with the quality of the used sand.
  • the duration of the treatment of the old sand can be set for each control module M1 to M n .
  • the friction intensity in the grater can be varied in various ways, for example by changing the pressure of the reaming tools, by fluidizing the friction space, by quickly removing the used sand from the friction zone, etc.
  • a grater that offers these possibilities offers is described in the earlier patent application P 42 37 838 of the applicant.
  • the dedusting capacity can be varied in a simple manner in that purge air is conveyed in a controlled manner into the tundish into which the old sand arrives.
  • SAND TYPE CONTROL MODULE SEQUENCE Core sand without bentonite sand M1, M2, M3, M4 Core sand with dry, still burned bentonite sand M5, M2, M3, M4 Core sand with moist, active bentonite sand M6, M2, M3, M4 Dry bentonite sand with little core sand M3, M2, M3, M2 M3, M4 Moist bentonite sand with little core sand M6, M2, M3, M2 M3, M4 Core sand with relatively much core breakage M7, M2, M3, M4
  • the quality of the used sand can be significant compared to the batch smaller sample can be determined in an analysis generator, which consists of a grinder and a dedusting device, whereby a selection of physical properties of the used sand is measured, e.g. its moisture content, fine fraction (sieve analysis), loss of ignition, dust density, etc.
  • the measured values obtained can be determined using a program Control modules M1 to M n and a certain sequence of control modules are assigned.
  • the measured values determined by means of the analysis generator can thus be used directly to control the control modules and their sequence on the control device for the regeneration of the old sand.
  • a test vessel into which the old sand is filled to a defined level.
  • the filled sample is added or applied several times with a constant drop weight and the pressure curve is recorded at the bottom of the sample or the sample vessel.
  • Statements about the sand type can be made from the pressure maximum and the pressure curve over time.
  • Fig. 1 shows a diagram in which the absorbed force is plotted against time. Curve A is typical of used sand with low fines (slurry), for example core sand, while curve B is typical of used sand with high fines (slurry), eg bentonite-bound molding sand.
  • Another method for obtaining a quality statement about the old sand is that a sample of the old sand with a certain mass is dried in a microwave dryer, the temperature profile over time is measured in the sample and the temperature profile curve that qualifies the old sand is used to control the control modules and their sequence.
  • a sample with a defined mass is dried in a microwave dryer.
  • Fig. 2 two typical curves are shown.
  • Curve C has an extensive plateau at 100 ° C, the old sand consequently contains a larger proportion of water, while the old sand according to curve D contains practically no residual moisture.
  • Another characteristic is the varying degree of increase after the 100 ° C plateau.
  • the sharp rise in curve C is due to an appreciable carbon content, which leads to rapid and strong heating of the sample, while curve D shows a relatively flat constant temperature rise.
  • Curve C is typical of a wet cast sand, while curve D is representative of a core sand.
  • a further possibility for qualifying the used sand, in particular with regard to the fine and very fine fractions present, is possible according to the invention in that a sample of the used sand is poured into an open test vessel and pressurized with compressed air from below, the pressure of which is adjusted so that all particles float below a certain particle size and are discharged, and that above the level of the sample the turbidity of the air flow and its time course which qualifies the old sand are recorded and the turbidity curve is used to control the control modules and their sequence.
  • This turbidity measurement which is known per se in the analysis of gas / solid dispersions, in turn provides a maximum turbidity value and a time course of the turbidity value.
  • a steep rise and a high maximum value speak for bentonite-bound molding sand or a high proportion of the same in the old sand, e.g. for old sand from the cast unpacking area, while low turbidity values speak for core sand or old sand from the area of the foundry.
  • Another possibility of qualifying the just processed used sand during its treatment is possible according to the invention in that during the dedusting of the used sand treated in the grater Discharged dust is collected and the amount of dust accumulated per unit of time is recorded gravimetrically or volumetrically, the temporal dust quantity gradient obtained in this way is recorded, and the height of the dust quantity gradient and its shape is used to adjust the duration of the treatment in the grater.
  • the amount of dust pneumatically separated during processing allows a statement to be made about the composition of the used sand, in particular about the predominant binder. It can therefore be used both the temporal dust quantity gradient and the absolute height of the dust quantity gradient and its shape, in particular to influence the duration of the mechanical processing within the control modules M 1 to M n .
  • the old sand is dedusted before the treatment and the dust quantity gradient is recorded during the dedusting. It has been shown, for example, that in the case of used sand with a low bentonite content but high organic binder content or also in the case of core sands, the dust content during the dedusting is relatively low, so that the dedusting time can also be measured briefly. Likewise, this type of used sand requires a relatively short mechanical processing and a short dedusting in the final pneumatic cleaning phase. A low dust level therefore speaks for synthetic resin-bound molding sand or a high proportion of core sand.
  • bentonite-bound used sand shows a high and almost constant dust level during dedusting, which only drops significantly after a certain period.
  • the process can also be optimized in that used sand, which is as dust-free as possible, enters the mechanical processing stage, since the dust content in the used sand leads to a reduction in the friction and abrasion forces effective on the used sand grain.
  • the dust acts as a lubricant, so to speak.
  • Such graters of the type mentioned here are usually driven by an electric motor.
  • the friction and abrasion effect on the used sand grain is immediately apparent from the power consumption of the drive motor. This current consumption can therefore be measured and the measured value can be used as a manipulated variable for the duration of the treatment of the used sand.
  • the pile driving, microwave drying and turbidity measurement methods described above for qualifying the used sand can be carried out before, but also during the treatment of the old sand. They can also be used to determine the quality of the used sand leaving the grater. Finally, these measuring methods can be carried out manually or automatically.
  • FIG. 3 shows a schematic representation of an embodiment of a plant for carrying out the process.
  • the old foundry sand is fed via a feed container 1, drawn off from there by means of a conveyor 2 and placed on a vibrating sieve 3, which is used to retain larger sand bulbs, impurities or the like.
  • the sieve passage namely the old sand to be processed, reaches a conveyor 4, to which a magnetic separator 5 is assigned and which feeds the old sand to a pneumatic transmitter 6, which feeds the old sand into one of the storage bunkers 7, 8, 9 or via a direct line 10 to a dryer 11 feeds.
  • the dryer 11 is also connected via a pneumatic conveyor line 12 and a pneumatic transmitter 13 to the old sand bunkers 7, 8 and 9.
  • the dryer 11 which is preferably designed as a fluidized bed dryer and is therefore connected to a blower 15 via a line 14, opens into an intermediate vessel 16 on the outlet side for dedusting the old sand.
  • This intermediate vessel is in turn supplied with purge air by the blower 15 via the line 17.
  • a plurality of friction devices 19 are connected via down pipes 18, in which the used sand flowing in via the lines 18 is subjected to frictional and abrasive forces.
  • the rubbing and scouring zone of the graters Old sand leaving 19 is in turn pneumatically fed back into the intermediate vessel 16 via the lines 21 by means of the blower 20, possibly in several cycles, where it is continuously dedusted.
  • the old sand 16 passes via a down pipe 22 into a container 23, which may collect several batches, on the outlet side of which a pneumatic transmitter 24 is arranged, which conveys the regenerated sand via the line 25 into a dedusting device 26, from where the regenerated sand - possibly via a further sieve 27 - reaches a pneumatic transmitter 28.
  • This conveys the regenerated sand into one of the regenerated sand bunkers 29, 30 or 31, in which different types of sand may be stored.
  • the regenerated sand is returned from the regenerated sand bunkers 29, 30 and 31 to the foundry by means of a pneumatic transmitter 33.
  • the dust cycle is described below:
  • the dust accumulating on the feed container 1 and in the area of the conveyor 2 and the screening machine 3 is conveyed directly into the dust collector 34.
  • the dust accumulating during the treatment in the fluid bed dryer 11 and in the intermediate vessel 16 passes via the lines 35 and 36 into a device 37 and 38, respectively, in which the amount of dust and its accumulation over time are recorded gravimetrically.
  • the old sand bunkers 7, 8 and 9 are also connected to the dust collector 34 via the lines 42 and the dedusting device 26 via the line 43, and the old sand bunkers 29, 30 and 31 via the line 44.
  • the dust collected there can also get into the Line 40 and thus be promoted to the dust bunker 41 for recycling.
  • the described rubbers 19, which are connected to the intermediate vessel 16 in the circuit, can in principle be of any design.
  • graters are used, as described in the applicant's earlier patent application P 42 37 830.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Processing Of Solid Wastes (AREA)
EP94108072A 1993-06-01 1994-05-26 Procédé pour la régénération de sable de fonderie usé Expired - Lifetime EP0628367B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4318136A DE4318136A1 (de) 1993-06-01 1993-06-01 Verfahren zum Regenerieren von Gießerei-Altsanden
DE4318136 1993-06-01

Publications (3)

Publication Number Publication Date
EP0628367A2 true EP0628367A2 (fr) 1994-12-14
EP0628367A3 EP0628367A3 (fr) 1995-04-26
EP0628367B1 EP0628367B1 (fr) 1998-11-04

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94108072A Expired - Lifetime EP0628367B1 (fr) 1993-06-01 1994-05-26 Procédé pour la régénération de sable de fonderie usé

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EP (1) EP0628367B1 (fr)
AT (1) ATE172902T1 (fr)
DE (2) DE4318136A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011075631B4 (de) * 2011-05-11 2021-10-28 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Prüfung der Qualität von Regeneratsand
DE102011075630B4 (de) * 2011-05-11 2022-03-03 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Prüfung der Qualität von Regeneratsand

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU387778A1 (ru) * 1971-05-31 1973-06-22 М. А. Осипов Оротуканский завод горного оборудовани Установка для сухой регенерации зернистых
EP0343272A1 (fr) * 1988-05-26 1989-11-29 Pohl Giessereitechnik Procédé et dispositif pour la régénération de sable décoché de fonderie
WO1993020964A1 (fr) * 1992-04-10 1993-10-28 Dietmar Boenisch Procede et dispositif de regeneration de sable de fonderie
EP0580084A2 (fr) * 1992-07-24 1994-01-26 Dietmar Prof. Dr.-Ing. Boenisch Appareil et procédé pour la régénération de sable de fonderie
DE4237838A1 (de) * 1992-11-10 1994-05-11 Badische Maschf Gmbh Verfahren und Vorrichtung zum Regenerieren von Gießereialtsand

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU387778A1 (ru) * 1971-05-31 1973-06-22 М. А. Осипов Оротуканский завод горного оборудовани Установка для сухой регенерации зернистых
EP0343272A1 (fr) * 1988-05-26 1989-11-29 Pohl Giessereitechnik Procédé et dispositif pour la régénération de sable décoché de fonderie
WO1993020964A1 (fr) * 1992-04-10 1993-10-28 Dietmar Boenisch Procede et dispositif de regeneration de sable de fonderie
EP0580084A2 (fr) * 1992-07-24 1994-01-26 Dietmar Prof. Dr.-Ing. Boenisch Appareil et procédé pour la régénération de sable de fonderie
DE4237838A1 (de) * 1992-11-10 1994-05-11 Badische Maschf Gmbh Verfahren und Vorrichtung zum Regenerieren von Gießereialtsand

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 7412, Derwent Publications Ltd., London, GB; AN 74-22588V Ÿ12! & SU-A-387 778 (OROTUKANSK MINING EQUIP) 17. Oktober 1973 *
WALTER STUZMANN ET AL. 'Ein- und mehrstufige Sandregenerieranlagen im Modulsystem- Anlagenkonzeption und Betriebsergebnisse' , GIESSEREI 79 (1992) 3 FEBRUAR, NO 3 , D}SSELDORF * Seite 113, rechte Spalte, Absatz 2 - Seite 114, linke Spalte, letzter Absatz * *

Also Published As

Publication number Publication date
DE59407204D1 (de) 1998-12-10
EP0628367B1 (fr) 1998-11-04
EP0628367A3 (fr) 1995-04-26
ATE172902T1 (de) 1998-11-15
DE4318136A1 (de) 1994-12-08

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