EP0476342A1 - Process for regenerating used foundry sand - Google Patents

Process for regenerating used foundry sand Download PDF

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Publication number
EP0476342A1
EP0476342A1 EP91114045A EP91114045A EP0476342A1 EP 0476342 A1 EP0476342 A1 EP 0476342A1 EP 91114045 A EP91114045 A EP 91114045A EP 91114045 A EP91114045 A EP 91114045A EP 0476342 A1 EP0476342 A1 EP 0476342A1
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EP
European Patent Office
Prior art keywords
sand
grains
basic
separated
abrasion
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.)
Withdrawn
Application number
EP91114045A
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German (de)
French (fr)
Inventor
Hermann Jacob
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.)
Georg Fischer AG
Original Assignee
Georg Fischer AG
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 Georg Fischer AG filed Critical Georg Fischer AG
Publication of EP0476342A1 publication Critical patent/EP0476342A1/en
Withdrawn legal-status Critical Current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
    • B22C5/08—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by sprinkling, cooling, or drying
    • 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
    • B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
    • 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

Definitions

  • the present invention relates to a method for the regeneration treatment of old foundry sands for reuse instead of core sand, wherein portions of binding agents are first separated from the granular matrix.
  • the object of the present invention is to propose a method for the regeneration treatment of old foundry sands, in which the regenerate can be used as core sand, the individual grains of sand being freed from additives in such a way that they can no longer negatively influence the hardening process during core production.
  • Molds are usually used to make castings. Due to the thermal action of the liquid metal, the sand is partly destroyed due to the additives used due to the high temperatures of the liquid metal and is therefore unusable. Cores that are used to form the voids in the castings are destroyed when the castings are unpacked and mixed with the bentonite-bonded sand. This mixture of bentonite-bound used sand and core sands is basic and cannot be used for the acid-reacting core binders.
  • the basic constituents adhering to the individual sand grains could either be partially removed by abrasion, or they could be evaporated while heating to the evaporation temperature of the basic constituents.
  • the volatilization temperature of the basic components is relatively low between 50 and 70 ° C.
  • the waste sand obtained from the foundry is first treated mechanically-pneumatically in a known manner in a first stage, i.e. the outer, burnt, dead-burned oolithization casings surrounding the individual grains of sand are blown away by abrasion, impact and impact effects.
  • the pre-cleaned sand mixture is loosened up by means of pulsating steel wool packets in such a way that the individual grains are exposed to abrasion contact with the steel wool.
  • heated air is drawn through the steel wool packets so that the volatilization of the basic components is initiated.
  • the evaporating portion of basic substances is extracted and the rubbed off basic constituents are removed as fine dust.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
  • Mold Materials And Core Materials (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Abstract

In the proposed process for regenerating used foundry sand, the mechanically precleaned sand grains are subjected to a further treatment in which the basic constituents still adhering to the grains are separated from the latter. <??>The advantage of the process is that the regenerated material can then be used as core sand without adversely affecting the dry curing process chemically since it is too basic.

Description

Die vorliegende Erfindung betrifft ein Verfahren zur Regenerierbehandlung von Giesserei-Altsanden für die Wiederverwendung anstelle von Kernsand, wobei zunächst Anteile von Bindestoffen von der körnigen Grundmasse getrennt werden.The present invention relates to a method for the regeneration treatment of old foundry sands for reuse instead of core sand, wherein portions of binding agents are first separated from the granular matrix.

Es sind verschiedene Verfahren zur Behandlung von Giesserei-Altsanden bekannt, die verbrauchte Zuschlagstoffe und deren verkokte Rückstände etc. von den Quarzkörnern trennen, um so wenigstens den in grossen Mengen anfallenden Quarzsand einer neuerlichen Wiederverwendung zuzuführen. Insbesondere unterscheidet man mechanische und thermische Regenerierungsverfahren. Bei dem mechanischen Verfahren wird mittels Prall- und Scheuerwirkung eine gewisse Reinigung des Kornes erzielt. Bei den thermischen Verfahren werden die an den Körnern vorhandenen Binderschalen und Umhüllungen etc. verbrannt.Various methods are known for the treatment of old foundry sands which separate used aggregates and their coked residues etc. from the quartz grains, so that at least the quartz sand accumulating in large quantities can be reused. A distinction is made in particular between mechanical and thermal regeneration processes. In the mechanical process, a certain cleaning of the grain is achieved by means of impact and abrasive effects. In the thermal processes, the binder shells and wrappings etc. present on the grains are burned.

Die Trennung von Quarzsand und verbrauchter Bindemittel etc. gelingt nach den vorgenannten Verfahren recht unterschiedlich in Bezug auf den, die Einzelkörner noch umfangenden Stoffe. Ausserdem bedarf das thermische Regenerierungsverfahren wegen seiner Umweltbelastung zusätzlicher Entsorgungsmassnahmen.The separation of quartz sand and used binding agent etc. succeeds quite differently according to the above-mentioned processes with regard to the substances still comprising the individual grains. In addition, the thermal regeneration process requires additional disposal measures due to its environmental impact.

Die vorliegende Erfindung stellt sich die Aufgabe ein Verfahren zur Regenerierbehandlung von Giesserei-Altsanden vorzuschlagen, bei dem das Regenerat als Kernsand verwendbar ist, wobei die einzelnen Sandkörner derart von Zuschlagstoffen befreit werden, dass sie den Aushärtungsvorgang bei der Kernherstellung nicht mehr negativ beeinflussen können.The object of the present invention is to propose a method for the regeneration treatment of old foundry sands, in which the regenerate can be used as core sand, the individual grains of sand being freed from additives in such a way that they can no longer negatively influence the hardening process during core production.

Diese Aufgabe wird erfindungsgemäss durch die Lehre des Anspruches 1 gelöst.According to the invention, this object is achieved by the teaching of claim 1.

Bei der Herstellung von Gussstücken werden in der Regel meistens aus Formsand gebildete Formen verwendet. Durch die thermische Einwirkung des flüssigen Metalles wird der Sand wegen der verwendeten Zuschlagstoffe infolge der hohen Temperaturen des flüssigen Metalls , teilweise zerstört und so unbrauchbar. Kerne, die zur Bildung der Hohl räume in den Gussstücken dienen, werden beim Auspacken der Gussstücke zerstört und mit dem bentonitgebundenen Sand vermischt. Diese Mischung von bentonitgebundenem Altsand und Kernsanden ist basisch, und so nicht für die sauer reagierenden Kernbinder verwendbar.Molds are usually used to make castings. Due to the thermal action of the liquid metal, the sand is partly destroyed due to the additives used due to the high temperatures of the liquid metal and is therefore unusable. Cores that are used to form the voids in the castings are destroyed when the castings are unpacked and mixed with the bentonite-bonded sand. This mixture of bentonite-bound used sand and core sands is basic and cannot be used for the acid-reacting core binders.

Es wurde festgestellt, dass an den Sandkörnern beträchtliche basische Bestandteile wie Amine, Soda oder Natriumhydroxit anhaften, selbst nach einer pneumatischen-mechanischen Regenerierbehandlung. Durch Probeentnahme kann der pH-Wert ermittelt werden und somit auf den Zustand des Sandgemisches und seines Wiedereinsatzes Rückschluss gezogen werden.
Diese basischen Bestandteile können selbstverständlich auch ausser Verbrennung des gesamten Sandgemisches durch Auswaschen in einer Emulsion bzw. wässerigen Lösung entfernt werden.It has been found that considerable basic constituents such as amines, soda or sodium hydroxide adhere to the sand grains, even after a pneumatic-mechanical regeneration treatment. The pH value can be determined by taking a sample and thus drawing conclusions about the condition of the sand mixture and its reuse.
These basic constituents can of course also be removed by burning them out in an emulsion or aqueous solution, apart from burning the entire sand mixture.

Anmelderseits wurde jedoch erkannt, dass die an den einzelnen Sandkörnern anhaftenden basischen Bestandteile entweder mittels Abrieb einmal zum Teil entfernt, oder bei gleichzeitiger Erwärmung auf die Verdampfungstemperatur der basischen Bestandteile zur Verflüchtigung gebracht werden können. Die Verflüchtigungstemperatur der basischen Bestandteile liegt relativ tief zwischen 50 und 70° C.However, it was recognized on the part of the applicant that the basic constituents adhering to the individual sand grains could either be partially removed by abrasion, or they could be evaporated while heating to the evaporation temperature of the basic constituents. The volatilization temperature of the basic components is relatively low between 50 and 70 ° C.

Beim erfindungsgemässen Verfahren wird der aus der Giesserei anfallende Altsand in einer ersten Stufe zunächst auf bekannte Art und Weise mechanisch-pneumatisch behandelt, d.h. durch Scheuer-, Schlag- und Prallwirkung werden die äusseren, den einzelnen Sandkorn umgebenden totgebrannten Oolithisierungshüllen weggesprengt.In the method according to the invention, the waste sand obtained from the foundry is first treated mechanically-pneumatically in a known manner in a first stage, i.e. the outer, burnt, dead-burned oolithization casings surrounding the individual grains of sand are blown away by abrasion, impact and impact effects.

In einer zweiten Verfahrensstufe wird das vorgereinigte Sandgemisch mittels pulsierender Stahlwollenpakete derart aufgelockert, dass die einzelnen Körner dem Abriebkontakt mit der Stahlwolle exponiert werden. Gleichzeitig wird erwärmte Luft durch die Stahlwollenpakete gezogen, so dass die Verflüchtigung der basischen Bestandteile eingeleitet wird. Gleichzeitig wird der verdampfende Anteil basischer Stoffe abgesaugt und die abgeriebenen basischen Bestandteile als Feinstaub abgeführt.In a second process stage, the pre-cleaned sand mixture is loosened up by means of pulsating steel wool packets in such a way that the individual grains are exposed to abrasion contact with the steel wool. At the same time, heated air is drawn through the steel wool packets so that the volatilization of the basic components is initiated. At the same time, the evaporating portion of basic substances is extracted and the rubbed off basic constituents are removed as fine dust.

Claims (6)

1. Verfahren zur Regenerierbehandlung von Giesserei-Altsanden für die Wiederverwendung anstelle von Kernsand, wobei zunächst Anteile von Bindestoffen von der körnigen Grundmasse getrennt werden, dadurch gekennzeichnet, dass die vorgereinigten Sandkörner einer weiteren Behandlung unterzogen werden, bei der die basischen Bestandteile, die noch an den Körnern haften, von diesen getrennt werden.1. Process for the regeneration treatment of old foundry sands for reuse instead of core sand, whereby portions of binding agents are first separated from the granular matrix, characterized in that the pre-cleaned grains of sand are subjected to a further treatment in which the basic constituents which are still present stick to the grains, be separated from them. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die basischen Bestandteile durch Abrieb von den Körnern getrennt werden.2. The method according to claim 1, characterized in that the basic constituents are separated from the grains by abrasion. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet,dass die basischen Bestandteile durch Erwärmen zum Siedepunkt und dann zur Verflüchtigung gebracht werden.3. The method according to claim 1, characterized in that the basic constituents are brought to the boiling point by heating and then volatilized. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die basischen Bestandteile während des Trennungsvorganges kontinuierlich abgesaugt werden.4. The method according to any one of claims 1 to 3, characterized in that the basic components are continuously sucked off during the separation process. 5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Sandkörner während des Abriebvorganges mittels eines Luftstromes aufgelockert und auf eine vorbestimmte Temperatur zwischen 50 - 70 ° C gebracht werden, bei der die Verflüchtigung der basischen Teile einsetzt.5. The method according to any one of claims 1 to 4, characterized in that the grains of sand loosened during the abrasion process by means of an air stream and brought to a predetermined temperature between 50 - 70 ° C, at which the volatilization of the basic parts begins. 6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Abriebvorgang mittels einer mechanischen Einrichtung, die Stahlwollenpakete enthält, ausgeführt wird, wobei die pulsierenden Stahlwollenpakete eine Einzelkornbehandlung ermöglichen.6. The method according to any one of claims 1 to 5, characterized in that the abrasion process is carried out by means of a mechanical device which contains steel wool packets, the pulsating steel wool packets allowing individual grain treatment.
EP91114045A 1990-09-05 1991-08-22 Process for regenerating used foundry sand Withdrawn EP0476342A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2897/90A CH681067A5 (en) 1990-09-05 1990-09-05
CH2897/90 1990-09-05

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EP0476342A1 true EP0476342A1 (en) 1992-03-25

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US (1) US5163496A (en)
EP (1) EP0476342A1 (en)
JP (1) JPH04231141A (en)
CH (1) CH681067A5 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5347069A (en) * 1992-10-27 1994-09-13 Chevron Research And Technology Company Treating oily wastes
KR20010113871A (en) * 2000-01-28 2001-12-28 니시 마코토 Method and device for collapsing and separating mold material and mold green sand from green sand mold
WO2001064371A1 (en) * 2000-03-02 2001-09-07 Sintokogio, Ltd. Collected sand processing method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2259660A1 (en) * 1974-02-01 1975-08-29 Jacob Hermann
FR2390227A1 (en) * 1977-05-11 1978-12-08 Levy Co Edward C PROCESS FOR RECOVERING FOUNDRY SAND RESIDUES AND NEW PRODUCTS THUS OBTAINED
EP0125384A1 (en) * 1983-03-16 1984-11-21 Hubert Eirich Method of regenerating used foundry sand and device for carrying out the method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60216949A (en) * 1984-04-11 1985-10-30 Nippon Kokan Keishiyu Kk Reconditioning method of molding sand

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2259660A1 (en) * 1974-02-01 1975-08-29 Jacob Hermann
FR2390227A1 (en) * 1977-05-11 1978-12-08 Levy Co Edward C PROCESS FOR RECOVERING FOUNDRY SAND RESIDUES AND NEW PRODUCTS THUS OBTAINED
EP0125384A1 (en) * 1983-03-16 1984-11-21 Hubert Eirich Method of regenerating used foundry sand and device for carrying out the method

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
* Seite 353, Spalte 1, Zeile 20 - Spalte 2, Zeile 21 * *
GIESSEREI Bd. 74, Nr. 10, 11. Mai 1987, DÜSSELDORF, GERMANY Seiten 318 - 321; M. RUZBEHI: 'THERMO-MECHANISCHE REGENERIERUNG VON FORMSTOFFEN MIT EINEM WASSERGLAS-ESTER-BINDERSYSTEM' *
GIESSEREI Bd. 76, Nr. 10, 15. Mai 1976, DÜSSELDORF Seiten 350 - 358; E.W. WELTZLAR: 'MöGLICHKEITEN UND GRENZEN BEI DER REGENERIERUNG VON GIESSEREIALTSANDEN' *

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CH681067A5 (en) 1993-01-15
US5163496A (en) 1992-11-17
JPH04231141A (en) 1992-08-20

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