EP0313830A2 - Process for hardening moulding sand articles - Google Patents

Process for hardening moulding sand articles Download PDF

Info

Publication number
EP0313830A2
EP0313830A2 EP88115750A EP88115750A EP0313830A2 EP 0313830 A2 EP0313830 A2 EP 0313830A2 EP 88115750 A EP88115750 A EP 88115750A EP 88115750 A EP88115750 A EP 88115750A EP 0313830 A2 EP0313830 A2 EP 0313830A2
Authority
EP
European Patent Office
Prior art keywords
membrane
permeate
catalyst
carrier gas
mixture
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
EP88115750A
Other languages
German (de)
French (fr)
Other versions
EP0313830A3 (en
EP0313830B1 (en
Inventor
Dieter Nisi
Helmut Dr. Paul
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.)
Daimler Benz AG
Original Assignee
Daimler Benz 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 Daimler Benz AG filed Critical Daimler Benz AG
Priority to AT88115750T priority Critical patent/ATE62839T1/en
Publication of EP0313830A2 publication Critical patent/EP0313830A2/en
Publication of EP0313830A3 publication Critical patent/EP0313830A3/en
Application granted granted Critical
Publication of EP0313830B1 publication Critical patent/EP0313830B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B22C9/123—Gas-hardening

Definitions

  • the invention relates to a method for curing sand moldings, in particular casting cores, made of synthetic resin-bonded sand by means of gaseous or vaporous catalyst which is added to a carrier gas, after which the catalyst / carrier gas mixture is pressed through the mold containing the loose sand moldings, the escaping from the mold Gas mixture is collected as completely as possible without mixing with ambient air, the catalyst portion of the gas mixture is separated out of it as completely as possible by condensation and, if necessary, is reused after separation of impurities.
  • the process described at the outset is described in detail in DE-PS 25 50 588.
  • cores with good bending and abrasion resistance, high dimensional accuracy and surface quality as well as good storability can be produced from cold molds in very short cycle times.
  • the sand mixture for this process consists of dry quartz sand and a liquid two-component synthetic resin binder system, which hardens when the catalyst is entered.
  • Catalysts which are used are liquid amines which are readily wettable at room temperature, most often triethylamine, dimethylethylamine or dimethylispropylamine.
  • the amines are malodorous and toxic, they must not be released into the environment.
  • the catalyst and the catalyst-containing exhaust gas can then, if necessary after removal of impurities, for. For example, by fractional distillation.
  • a general disadvantage of this method is that the catalyst is only present in a relatively low concentration in the carrier gas mixture. To remove the catalyst, a strong cooling of the entire gas stream is therefore necessary, which is associated with high costs. Despite the high price of the catalyst, the process has therefore not been able to gain acceptance in practice.
  • the object of the invention is therefore to enable the catalyst to be recovered more cheaply in a process for curing sand moldings. This object is achieved in a method according to the preamble of claim 1 by the characterizing Features solved.
  • the essence of the invention is thus that the catalyst / carrier gas mixture which escapes from the mold is no longer condensed directly, but that, after permeation through a semipermeable membrane, a gas mixture enriched in catalyst is produced, from which the catalyst is then produced at a lower cost, for example by condensation can be recovered.
  • the gas mixture escaping from the mold is passed over the mixture feed side of a semi-permeable membrane, which preferably allows the catalyst portions of the gas mixture to permeate through it.
  • a semi-permeable membrane which preferably allows the catalyst portions of the gas mixture to permeate through it.
  • a membrane which is suitable in the present process, consists, for example, of polydimethylsiloxane.
  • the driving force for the passage of the catalyst is a partial pressure drop between the mixture feed side of the membrane and the back, the so-called permeate side.
  • This concentration gradient is generated in that a lower pressure is maintained on the permeate side of the membrane than it is on the mixture supply side.
  • the partial pressure drop on the permeate side is increased by passing a permeate carrier gas stream over the permeate side of the membrane which is greater than the permeate stream permeating through the membrane.
  • a permeate carrier gas stream which is approximately 50 to 300 l above the permeate volume passing through the membrane per m 2 and hour is preferred. Air or nitrogen is used as the carrier gas. Nitrogen is preferred because it does not produce explosive mixtures with the catalyst vapors that pass through.
  • a cleaning step for example a fractional distillation, is required before reusing the catalyst.
  • the separation of substance mixtures with the aid of membranes is known in principle, for example from US Pat. No. 4,553,983, in which the recovery of solvents is described, in particular from painting systems.
  • the basic statements made there regarding permeation can surprisingly also be applied to the permeation of the strongly polar, basic amines used as catalysts in the production of the mold, although the paint solvents are neutral and essentially non-polar.
  • the catalyst-containing gas mixture escaping from the forms of the core shooter 1 passes via line 2 into the filter 3, in which the gas mixture is cleaned of mechanical impurities such as sand, dust and the like. With the help of the fan 4, the gas mixture is then passed over the mixture supply side 5 of the membrane module 25.
  • a separation module a large number of separation membranes are arranged in a very small space. Pipe, plate, winding and capillary systems can be used as modules.
  • the arrangement of the separating membrane in modules has the purpose of accommodating the largest possible membrane area in the smallest possible space. For the sake of simplicity, however, only a single membrane is shown in the figure.
  • the permeability of the membrane to the catalyst should be as high as possible and as low as possible to the carrier gas mixture. In order to achieve the highest possible flow of the catalyst vapors through the membrane, this must be as thin as possible. Since the mechanical stability decreases greatly with thin membranes, it is common to arrange the membrane on a support. Suitable carriers are, for example, microporous films, as are also used in ultrafiltration. A suitable membrane material that enables good separation between the carrier gas and the catalyst is e.g. B. polydimethylsiloxane.
  • the gas mixture depleted of catalyst leaves the separation module 25 through line 12 and is fed again to the core shooter 1 via line 14 with the aid of the compressor 15.
  • nitrogen can be added to the gas stream from the container 16 or compressed air through the line 17.
  • Fresh gas from the containers 20 or 21 is metered into the gas stream via line 19 with the aid of the pump 18.
  • the catalyst-containing gas stream can be brought to its optimal temperature. If the entire gas stream emerging from the membrane separation module 25 through the line 12 is not recycled, the excess, if appropriate after a treatment 13 (for example an acid wash), can be passed outside through the line 26.
  • the catalyst permeating through the membrane 22 onto the permeate side 9 of the membrane separation module is sucked off via the line 6 by means of the vacuum pump 7 and freed of the condensable components in the condenser 8.
  • the depleted gas stream then arrives again via line 10 to the permeate side 9 of the membrane separation module 25.
  • a pressure of about 0.2-98%, in particular 0.2-20% of the pressure on the gas supply side 5 is maintained on the permeate side 9 of the separation module.
  • a permeate carrier gas stream which is larger than the permeate stream permeating through the membrane is passed over the permeate side 9. Since small amounts of carrier gas constantly enter the permeate circuit through the membrane, this excess is passed via line 11 into line 12, which contains the depleted catalyst / carrier gas mixture.
  • the temperature of the condenser 8 is expediently set in such a way that as few impurities as possible, such as water or other solvents, are also separated off and a high catalyst quality is thus produced. It is sometimes necessary to separate the condensate separated in the condenser in a separation unit 23 by distillation. In any case, the recovered catalyst is fed back through line 24, which is only partially shown, into the catalyst storage vessel 21. If the temperature of the condenser 8 is set so that as little impurities as possible, in particular water, arise during the condensation, then there is no need to fear an accumulation of impurities in the permeate-side circuit since the content of excess carrier gas is removed through line 11 of impurities in the permeate-side circuit always remains relatively low.
  • nitrogen from the container 16 or compressed air from line 17 can also be used worked as a carrier gas will.

Abstract

A process is described for curing sand moldings, in particular casting cores, by the cold box process. In this process a catalyst containing gas mixture escaping from the mold is passed over a mixture feed side of a semipermeable membrane while a pressure is maintained on the permeate side of the membrane which is less than the pressure on the mixture feed side, whereby the catalyst vapors preferentially permeate through the membrane, and a permeate carrier gas stream which is, in particular, 50 to 300 liters greater than the permeate stream passing through the membrane per m2 and per hour is passed over the permeate side of the membrane. The catalyst, in particular a tertiary amine, is greatly concentrated in the permeate carrier gas stream and can simply and inexpensively be removed from the latter by condensation. Inexpensive, virtually complete recovery of the expensive catalyst is possible using the process.

Description

Die Erfindung betrifft ein Verfahren zum Aushärten von Sandformkörpern, insbesondere Gießkernen, aus kunst­harzgebundenem Sand mittels gas- oder dampfförmigem Katalysator, der einem Trägergas zugegeben wird, wo­nach das Katalysator/Trägergasgemisch durch die den losen Sandformkörper enthaltende Form gepreßt wird, wo­bei das aus der Form entweichende Gasgemisch ohne Ver­mischung mit Umgebungsluft möglichst vollständig auf­gefangen, der Katalysatoranteil des Gasgemisches durch Kondensation möglichst vollständig daraus ausgeschie­den und ggf. nach Abtrennung von Verunreinigungen wie­der verwendet wird.The invention relates to a method for curing sand moldings, in particular casting cores, made of synthetic resin-bonded sand by means of gaseous or vaporous catalyst which is added to a carrier gas, after which the catalyst / carrier gas mixture is pressed through the mold containing the loose sand moldings, the escaping from the mold Gas mixture is collected as completely as possible without mixing with ambient air, the catalyst portion of the gas mixture is separated out of it as completely as possible by condensation and, if necessary, is reused after separation of impurities.

Das eingangs geschilderte Verfahren ist in DE-PS 25 50 588 ausführlich beschrieben. Nach diesem Kaltaushärtver­fahren lassen sich Kerne mit guter Biege- und Abrieb­festigkeit, hoher Maßgenauigkeit und Flächengüte sowie guter Lagerfähigkeit aus kalten Formwerkzeugen in sehr kurzen Taktzeiten herstellen. Die Sandmischung für dieses Verfahren besteht aus trockenem Quarzsand und einem flüssigen Zweikomponenten-Kunstharzbindersystem, welches bei Zutritt des Katalysators aushärtet.The process described at the outset is described in detail in DE-PS 25 50 588. Using this cold hardening process, cores with good bending and abrasion resistance, high dimensional accuracy and surface quality as well as good storability can be produced from cold molds in very short cycle times. The sand mixture for this process consists of dry quartz sand and a liquid two-component synthetic resin binder system, which hardens when the catalyst is entered.

Als Katalysatoren verwendet werden bei Raumtemperatur flüssige, leichtflichtige Amine, am häufigsten Tri­ethylamin, Dimethylethylamin oder Dimethylispropyl­amin.Catalysts which are used are liquid amines which are readily wettable at room temperature, most often triethylamine, dimethylethylamine or dimethylispropylamine.

Da die Amine übelriechend und giftig sind, dürfen sie nicht an die Umwelt gelangen. Neben der Entfernung der Amine aus dem Abluftstrom einer Kernherstellerei durch Säurewäsche, thermische Nachverbrennung oder Verbren­nung in einem Kupolofen nach Zuführung in den Heißwind­strom, wobei die Amine verloren gehen, ist aus der DE-PS 25 50 588 bekannt, aus dem katalysatorhaltigen Abgas den Katalysator und andere kondensierbare Dämpfe durch Kondensation abzuscheiden. Der Katalysator kann dann, ggf. nach einer Abtrennung von Verunreinigungen, z. Bsp. durch fraktionierte Destillation, wieder ver­wendet werden.Since the amines are malodorous and toxic, they must not be released into the environment. In addition to removing the amines from the exhaust air stream of a core manufacturing plant by acid washing, thermal afterburning or combustion in a cupola furnace after being fed into the hot wind stream, the amines being lost, it is known from DE-PS 25 50 588 that the catalyst and the catalyst-containing exhaust gas to separate other condensable vapors by condensation. The catalyst can then, if necessary after removal of impurities, for. For example, by fractional distillation.

Einen generellen Nachteil für dieses Verfahren stellt es dar, daß der Katalysator in dem Trägergasgemisch nur in einer verhältnismäßig geringen Konzentration vorhanden ist. Zur Entfernung des Katalysators ist da­her eine starke Abkühlung des gesamten Gasstromes er­forderlich, was mit hohen Kosten verbunden ist. Das Ver­fahren hat sich daher auch trotz des hohen Preises für den Katalysator in der Praxis nicht durchsetzen können.A general disadvantage of this method is that the catalyst is only present in a relatively low concentration in the carrier gas mixture. To remove the catalyst, a strong cooling of the entire gas stream is therefore necessary, which is associated with high costs. Despite the high price of the catalyst, the process has therefore not been able to gain acceptance in practice.

Die Aufgabe der Erfindung besteht daher darin, bei einem Verfahren zum Aushärten von Sandformkörpern die Rückge­winnung des Katalysators preiswerter zu ermöglichen. Diese Aufgabe wird bei einem Verfahren gemäß dem Ober­begriff des Patentanspruchs 1 durch dessen kennzeichnende Merkmale gelöst.The object of the invention is therefore to enable the catalyst to be recovered more cheaply in a process for curing sand moldings. This object is achieved in a method according to the preamble of claim 1 by the characterizing Features solved.

Das Wesen der Erfindung besteht somit darin, daß das aus der Form entweichende Katalysator/Trägergasgemisch nicht mehr direkt kondensiert wird, sondern daß nach Permeation durch eine semipermeable Membran ein an Katalysator ange­reichertes Gasgemisch erzeugt wird, aus dem dann der Kataly­sator mit geringeren Kosten z.B. durch Kondensation zurück­gewonnen werden kann. Das aus der Form entweichende Gasge­misch wird zu diesem Zweck über die Gemischzufuhrseite einer semipermeablen Membran geleitet, die bevorzugt die Kataly­sator anteile des Gasgemisches durch sich hindurchtreten (permeieren) läßt. Eine solche, in dem vorliegenden Ver­fahren geeignete Membran besteht z.B. aus Polydimethyl­siloxan. Die treibende Kraft für den Durchtritt des Kata­lysators bildet ein Partialdruckgefälle zwischen der Gemisch­zufuhrseite der Membran und der Rückseite, der sogenannten Permeatseite. Dieses Konzentrationsgefälle wird dadurch erzeugt, daß auf der Permeatseite der Membran ein geringerer Druck aufrechterhalten wird, als er auf der Gemischzufuhr­seite herrscht. Zusätzlich wird noch das Partialdruckgefälle auf der Permeatseite dadurch gesteigert, daß über die Per­meatseite der Membran ein Permeatträgergasstrom geleitet wird, der größer ist als der durch die Membrane permeierende Permeatstrom. Bevorzugt wird ein Permeatträgergasstrom, der etwa 50 bis 300 l über dem pro m² und Stunde durch die Membran hindurchtretenden Permeatvolumen liegt. Als Träger­gas wird Luft oder Stickstoff verwendet. Stickstoff wird deshalb bevorzugt, da dadurch mit den durchtretenden Katalysator­dämpfen keine explosiven Gemische entstehen können. Auf der Permeatseite liegt ein in Bezug auf den Katalysatorgehalt stark angereichertes Gasgemisch vor, aus dem die kondensierbaren Anteile in an sich bekannter Weise durch Kühlung entfernt werden können. Ggf. ist vor der Wiederverwendung des Kata­lysators noch ein Reinigungsschritt, z.B. eine fraktionierende Destillation, erforderlich. Die Trennung von Stoffgemischen mit Hilfe von Membranen ist prinzipiell bekannt, z.B. aus der US-PS 4,553,983, in der die Rückgewinnung von Lösemitteln insbesondere aus Lackier­anlagen beschrieben wird. Die dort gemachten prinzi­piellen Aussagen zur Permeation können überraschen­derweise auch auf die Permeation der bei der Form­herstellung als Katalysator benutzten stark polaren, basischen Amine, übertragen werden, obwohl die Lack­lösemittel neutral und im wesentlichen unpolar sind.The essence of the invention is thus that the catalyst / carrier gas mixture which escapes from the mold is no longer condensed directly, but that, after permeation through a semipermeable membrane, a gas mixture enriched in catalyst is produced, from which the catalyst is then produced at a lower cost, for example by condensation can be recovered. For this purpose, the gas mixture escaping from the mold is passed over the mixture feed side of a semi-permeable membrane, which preferably allows the catalyst portions of the gas mixture to permeate through it. Such a membrane, which is suitable in the present process, consists, for example, of polydimethylsiloxane. The driving force for the passage of the catalyst is a partial pressure drop between the mixture feed side of the membrane and the back, the so-called permeate side. This concentration gradient is generated in that a lower pressure is maintained on the permeate side of the membrane than it is on the mixture supply side. In addition, the partial pressure drop on the permeate side is increased by passing a permeate carrier gas stream over the permeate side of the membrane which is greater than the permeate stream permeating through the membrane. A permeate carrier gas stream which is approximately 50 to 300 l above the permeate volume passing through the membrane per m 2 and hour is preferred. Air or nitrogen is used as the carrier gas. Nitrogen is preferred because it does not produce explosive mixtures with the catalyst vapors that pass through. On the permeate side there is one that is highly enriched in terms of the catalyst content Gas mixture from which the condensable components can be removed by cooling in a manner known per se. Possibly. a cleaning step, for example a fractional distillation, is required before reusing the catalyst. The separation of substance mixtures with the aid of membranes is known in principle, for example from US Pat. No. 4,553,983, in which the recovery of solvents is described, in particular from painting systems. The basic statements made there regarding permeation can surprisingly also be applied to the permeation of the strongly polar, basic amines used as catalysts in the production of the mold, although the paint solvents are neutral and essentially non-polar.

Die Erfindung wird anhand der Abbildung weiter be­schrieben:The invention is further described with reference to the figure:

Das aus den Formen der Kernschießmaschine 1 ent­weichende katalysatorhaltige Gasgemisch gelangt über die Leitung 2 in den Filter 3, in der das Gasgemisch von mechanischen Verunreinigungen wie Sand, Staub und dgl. gereinigt wird. Mit Hilfe des Ventilators 4 wird das Gasgemisch dann über die Gemischzufuhrseite 5 des Membranmoduls 25 geleitet. In einem solchen Trennmo­dul sind eine Vielzahl von Trennmembranen auf engstem Raum angeordnet. Als Modul können Rohr-, Platten-, Wickel- und Kapillarsysteme verwendet werden. Die An­ordnung der Trennmembran in Modulen hat den Zweck, auf möglichst engem Raum eine möglichst große Membranfläche unterzubringen. Der Einfachheit halber ist in der Ab­bildung jedoch lediglich eine einzelne Membran darge­stellt. Um eine möglichst gute Trennwirkung zwischen dem Trägergasgemisch und dem Katalysator zu erreichen, soll die Permeabilität der Membran gegenüber dem Kata­lysator möglichst hoch und gegenüber dem Trägergasge­misch möglichst niedrig sein. Um einen möglichst hohen Strom der Katalysator-Dämpfe durch die Membran zu er­reichen, muß diese so dünn wie möglich sein. Da bei dünnen Membranen die mechanische Stabilität stark ab­nimmt, ist es üblich, die Membran auf einem Träger an­zuordnen. Als Träger geeignet sind z.B. mikroporöse Folien, wie sie auch bei der Ultrafiltration Verwen­dung finden. Ein geeignetes Membranmaterial, das eine gute Trennung zwischen dem Trägergas und dem Katalysator ermöglicht, ist z. B. Polydimethylsiloxan. Das an Kata­lysator abgereicherte Gasgemisch verläßt das Trennmo­dul 25 durch Leitung 12 und wird über Leitung 14 mit Hilfe des Kompressors 15 erneut der Kernschießmaschine 1 zugeführt. Im Bedarfsfall kann dem Gasstrom aus dem Be­hälter 16 Stickstoff oder durch die Leitung 17 Preßluft zugegeben werden. Über die Leitung 19 wird mit Hilfe der Pumpe 18 dem Gasstrom frischer Katalysator aus den Behältern 20 oder 21 zudosiert. Mit Hilfe der Temperier­einrichtung 22 kann der katalysatorhaltige Gasstrom auf seine optimale Temperatur gebracht werden. Falls nicht der gesamte durch die Leitung 12 aus dem Membran­trennmodul 25 austretende Gasstrom recycliert wird, kann der Überschuß, ggf. nach einer Aufbereitung 13 (z.B. einer Säurewäsche) durch die Leitung 26 ins Freie geleitet werden. Der durch die Membran 22 auf die Permeatseite 9 des Membrantrennmoduls permeierende Katalysator wird mit Hilfe der Vakuumpumpe 7 über die Leitung 6 abgesaugt und im Kondensator 8 von den kondensierbaren Anteilen befreit. Anschließend gelangt der abgereicherte Gasstrom über die Leitung 10 wieder auf die Permeatseite 9 des Mem­brantrennmoduls 25. Auf der Permeatseite 9 des Trennmoduls wird ein Druck von etwa 0,2 - 98 %,insbesondere 0,2-20% des Druckes auf der Gaszufuhrseite 5 liegt, aufrechterhalten. Zur beschleunigten Abfuhr des Katalysators von der Permeatseite der Membran wird über die Permeatseite 9 ein Permeat-Trägergasstrom ge­leitet, der größer ist als der durch die Membrane per­meierende Permeatstrom. Da durch die Membran ständig ge­ringe Mengen an Trägergas in den Permeatkreislauf gelangen, wird dieser Überschuß über die Leitung 11 in die Leitung 12, die das abgereicherte Katalysator/Trägergasgemisch ent­hält, geleitet. Die Temperatur des Kondensators 8 wird zweckmäßigerweise so eingestellt, daß möglichst wenig Ver­unreinigungen wie Wasser oder andere Lösungsmittel mit abgeschieden werden und so eine hohe Katalysatorqualität entsteht. Es ist mitunter notwendig, das im Kondensator abgeschiedene Kondensat in einer Trennanlage 23 durch Destillation zu zerlegen. In jedem Falle wird der rück­gewonnene Katalysator durch die nur teilweise dargestellte Leitung 24 in das Katalysatorvorratsgefäß 21 zurückgeleitet. Falls die Temperatur des Kondensators 8 so eingestellt ist, daß bei der Kondensation möglichst wenig Verunreinigungen, ins­besondere Wasser, entstehen, so ist eine Anreicherung von Ver­unreinigungen in dem permeatseitigen Kreislauf nicht zu be­fürchten, da durch die Abfuhr von überschüssigem Trägergas durch die Leitung 11 der Gehalt an Verunreinigungen im per­meatseitigen Kreislauf stets verhältnismäßig niedrig bleibt.The catalyst-containing gas mixture escaping from the forms of the core shooter 1 passes via line 2 into the filter 3, in which the gas mixture is cleaned of mechanical impurities such as sand, dust and the like. With the help of the fan 4, the gas mixture is then passed over the mixture supply side 5 of the membrane module 25. In such a separation module, a large number of separation membranes are arranged in a very small space. Pipe, plate, winding and capillary systems can be used as modules. The arrangement of the separating membrane in modules has the purpose of accommodating the largest possible membrane area in the smallest possible space. For the sake of simplicity, however, only a single membrane is shown in the figure. To ensure the best possible separation between To achieve the carrier gas mixture and the catalyst, the permeability of the membrane to the catalyst should be as high as possible and as low as possible to the carrier gas mixture. In order to achieve the highest possible flow of the catalyst vapors through the membrane, this must be as thin as possible. Since the mechanical stability decreases greatly with thin membranes, it is common to arrange the membrane on a support. Suitable carriers are, for example, microporous films, as are also used in ultrafiltration. A suitable membrane material that enables good separation between the carrier gas and the catalyst is e.g. B. polydimethylsiloxane. The gas mixture depleted of catalyst leaves the separation module 25 through line 12 and is fed again to the core shooter 1 via line 14 with the aid of the compressor 15. If necessary, nitrogen can be added to the gas stream from the container 16 or compressed air through the line 17. Fresh gas from the containers 20 or 21 is metered into the gas stream via line 19 with the aid of the pump 18. With the help of the temperature control device 22, the catalyst-containing gas stream can be brought to its optimal temperature. If the entire gas stream emerging from the membrane separation module 25 through the line 12 is not recycled, the excess, if appropriate after a treatment 13 (for example an acid wash), can be passed outside through the line 26. The catalyst permeating through the membrane 22 onto the permeate side 9 of the membrane separation module is sucked off via the line 6 by means of the vacuum pump 7 and freed of the condensable components in the condenser 8. The depleted gas stream then arrives again via line 10 to the permeate side 9 of the membrane separation module 25. A pressure of about 0.2-98%, in particular 0.2-20% of the pressure on the gas supply side 5 is maintained on the permeate side 9 of the separation module. In order to accelerate the removal of the catalyst from the permeate side of the membrane, a permeate carrier gas stream which is larger than the permeate stream permeating through the membrane is passed over the permeate side 9. Since small amounts of carrier gas constantly enter the permeate circuit through the membrane, this excess is passed via line 11 into line 12, which contains the depleted catalyst / carrier gas mixture. The temperature of the condenser 8 is expediently set in such a way that as few impurities as possible, such as water or other solvents, are also separated off and a high catalyst quality is thus produced. It is sometimes necessary to separate the condensate separated in the condenser in a separation unit 23 by distillation. In any case, the recovered catalyst is fed back through line 24, which is only partially shown, into the catalyst storage vessel 21. If the temperature of the condenser 8 is set so that as little impurities as possible, in particular water, arise during the condensation, then there is no need to fear an accumulation of impurities in the permeate-side circuit since the content of excess carrier gas is removed through line 11 of impurities in the permeate-side circuit always remains relatively low.

Falls es nicht beabsichtigt ist, das aus dem Membran­trennmodul 25 durch die Leitung 12 austretende, an Kataly­sator verarmte Gasgemisch durch Leitung 14 mit Hilfe des Kompressors 15 im Kreislauf in die Kernschießmaschine 1 zurückzuführen, kann auch mit Stickstoff aus dem Behälter 16 oder Preßluft aus Leitung 17 als Trägergas gearbeitet werden.If it is not intended to recycle the gas mixture depleted in catalyst from the membrane separation module 25 through the line 12 through line 14 with the aid of the compressor 15 in the circuit into the core shooting machine 1, nitrogen from the container 16 or compressed air from line 17 can also be used worked as a carrier gas will.

Mit dem Verfahren kann in einfacher und preiswerter Art und Weise der verhältnismäßig teure Katalysator nahezu vollstän­dig zurückgewonnen werden.With the method, the relatively expensive catalyst can be almost completely recovered in a simple and inexpensive manner.

Claims (3)

1. Verfahren zum Aushärten von Sandformkörpern, ins­besondere Gießkernen, aus kunstharzgebundenem Sand mittels gas- oder dampfförmigem Katalysator, der einem Trägergas zugegeben wird, wonach das Kataly­sator/Trägergemisch durch die den losen Sandformkörper enthaltende Form gepreßt wird, wobei das aus der Form entweichende Gasgemisch ohne Vermischung mit Umgebungs­luft möglichst vollständig aufgefangen, der Katalysa­toranteil des Gasgemisches durch Kondensation mög­lichst vollständig daraus ausgeschieden und ggf. nach der Abtrennung von Verunreinigungen wieder verwendet wird,
dadurch gekennzeichnet,
daß das aus der Form entweichende Gasgemisch über die Gemischzufuhrseite einer semipermeablen Membran geleitet wird, während auf der Permeatseite der Membran ein Druck aufrechterhalten wird, der geringer ist als der Druck auf der Gemischzufuhrseite, wodurch bevorzugt die Katalysatordämpfe durch die Membrane permeieren wobei über die Permeatseite der Membrane ein Permeat-­Trägergasstrom geleitet wird, der größer ist als der durch die Membrane hindurchgehende Permeatstrom und daß die Katalysatordämpfe aus dem Permeat-Trägergas­strom zurückgewonnen werden.1. A method for curing sand moldings, in particular casting cores, made of synthetic resin-bonded sand by means of gaseous or vaporous catalyst, which is added to a carrier gas, after which the catalyst / carrier mixture is pressed through the mold containing the loose sand moldings, the gas mixture escaping from the mold without Mixing with ambient air is collected as completely as possible, the catalyst portion of the gas mixture is separated out of it as completely as possible by condensation and possibly reused after the removal of impurities,
characterized,
that the gas mixture escaping from the mold is passed over the mixture feed side of a semi-permeable membrane, while a pressure is maintained on the permeate side of the membrane which is lower than the pressure on the mixture feed side, whereby the catalyst vapors preferentially permeate through the membrane, and over the permeate side of the membrane Membrane a permeate carrier gas stream is passed, which is greater than the permeate stream passing through the membrane and that the catalyst vapors are recovered from the permeate carrier gas stream. 2. Verfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß der Permeat-Trägergasstrom 50 bis 300 l über dem pro Quadratmeter und Stunde durch die Membrane durchtretenden Permeatstrom liegt.2. The method according to claim 1,
characterized,
that the permeate carrier gas stream is 50 to 300 l above the permeate stream passing through the membrane per square meter and hour. 3. Verfahren nach Anspruch 1 oder 2,
dadurch gekennzeichnet,
daß der Druck des Trägergasstromes 0,2 bis 20 % des Druckes des Gasstromes auf der Gemischzufuhrseite be­trägt.3. The method according to claim 1 or 2,
characterized,
that the pressure of the carrier gas stream is 0.2 to 20% of the pressure of the gas stream on the mixture feed side.
EP88115750A 1987-10-30 1988-09-24 Process for hardening moulding sand articles Expired - Lifetime EP0313830B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88115750T ATE62839T1 (en) 1987-10-30 1988-09-24 PROCESS FOR HARDENING SAND MOLDINGS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3736775A DE3736775C1 (en) 1987-10-30 1987-10-30 Process for hardening sand moldings
DE3736775 1987-10-30

Publications (3)

Publication Number Publication Date
EP0313830A2 true EP0313830A2 (en) 1989-05-03
EP0313830A3 EP0313830A3 (en) 1989-12-13
EP0313830B1 EP0313830B1 (en) 1991-04-24

Family

ID=6339404

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88115750A Expired - Lifetime EP0313830B1 (en) 1987-10-30 1988-09-24 Process for hardening moulding sand articles

Country Status (6)

Country Link
US (1) US4886105A (en)
EP (1) EP0313830B1 (en)
JP (1) JPH02121750A (en)
AT (1) ATE62839T1 (en)
DE (1) DE3736775C1 (en)
ES (1) ES2022563B3 (en)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4007798C1 (en) * 1990-03-12 1991-02-14 Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De Hardening sand mould members - comprises mixing catalyst with carrier gas, mixing with sand, pressing sand, retrieving gas and hardening
US5135043A (en) * 1990-06-25 1992-08-04 Omco Usa, Inc. Apparatus and method for gas curing foundry cores and molds
DE4120928A1 (en) * 1991-06-25 1993-01-07 Unterderweide Gmbh METHOD FOR CURING SAND MOLDED BODIES, IN PARTICULAR FOR FOUNDRIES
DE4206790C1 (en) * 1992-03-04 1993-04-01 Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De Hardening resin-bonded foundry sand cores with amine gas catalyst - with recovery of amine gas in sulphuric acid bath and association of amine sulphate by electrodialysis
DE4223776C1 (en) * 1992-07-18 1993-09-16 Mercedes-Benz Aktiengesellschaft, 70327 Stuttgart, De Recycling amine from sand moulding process - by progressively increasing pH of used gases in solution and removing amine by gravity separation
DE4225436C1 (en) * 1992-07-31 1993-11-25 Daimler Benz Ag Catalytic hardening of sand mould elements - with two-stage sepn. and removal of amine(s) and solvents from exhaust air
DE19549422C2 (en) * 1994-02-04 2001-05-10 Sommer Tech Entwicklungen Gmbh Mfg. cores for sand casting
DE19503832C2 (en) * 1994-02-04 1999-01-28 Sommer Tech Entwicklungen Gmbh Method and device for producing sand cores for metal casting
US20040051078A1 (en) * 2002-09-12 2004-03-18 Gernon Michael David Reactive amine catalysts for use in PUCB foundry binder
DE10356634B4 (en) * 2002-12-05 2006-03-30 Zimmermann, Jürgen, Dr. Method and apparatus for producing cores in core shooters
ES2739455T3 (en) 2007-01-22 2020-01-31 Arkema France Process for manufacturing cast iron forming cores and for casting metals
KR101488305B1 (en) * 2013-04-23 2015-01-30 현대자동차주식회사 Method and apparatus for recovering hardening catalyst of manufacturing process of core

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2550588B1 (en) * 1975-11-11 1976-07-01 Daimler Benz Ag Method and device for hardening sand mold bodies
DE2621153A1 (en) * 1976-05-13 1977-11-24 Daimler Benz Ag Hardening sand cores by cold box process - where catalyst is reclaimed from carrier gas after use
US4553983A (en) * 1984-07-31 1985-11-19 Membrane Technology And Research, Inc. Process for recovering organic vapors from air

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3104343A1 (en) * 1981-02-07 1982-09-16 Arasin Gmbh, 4223 Voerde METHOD AND DEVICE FOR RECOVERY OF AMINES FROM EXHAUST AIR CONTAINING AMINE
JPS58222A (en) * 1981-06-25 1983-01-05 Matsushita Seiko Co Ltd Gas supply device utilizing gas-selective high-polymer film
US4474586A (en) * 1983-12-05 1984-10-02 Monsanto Company Gas separation process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2550588B1 (en) * 1975-11-11 1976-07-01 Daimler Benz Ag Method and device for hardening sand mold bodies
DE2621153A1 (en) * 1976-05-13 1977-11-24 Daimler Benz Ag Hardening sand cores by cold box process - where catalyst is reclaimed from carrier gas after use
US4553983A (en) * 1984-07-31 1985-11-19 Membrane Technology And Research, Inc. Process for recovering organic vapors from air

Also Published As

Publication number Publication date
ES2022563B3 (en) 1991-12-01
JPH02121750A (en) 1990-05-09
DE3736775C1 (en) 1988-04-28
US4886105A (en) 1989-12-12
EP0313830A3 (en) 1989-12-13
EP0313830B1 (en) 1991-04-24
ATE62839T1 (en) 1991-05-15

Similar Documents

Publication Publication Date Title
EP0313830B1 (en) Process for hardening moulding sand articles
DE3541775A1 (en) METHOD FOR REMOVING SULFUR HYDROGEN FROM GAS MIXTURES
DE18702741T1 (en) METHOD FOR PURIFYING NATURAL VANILLIN
DE3614450C2 (en)
EP0876195B1 (en) Method of filtering the organic solutions arising in the production of circuit boards
DE69004428T2 (en) FILTERS AND METHOD FOR PRODUCING FILTERS USING A MATERIAL THAT CAN BE CURED BY UV RADIATION FOR THE END CAPS.
DE4130661C1 (en)
DE3002920A1 (en) METHOD FOR SEPARATING AUTOPOLYMERIZABLE HYDROCARBON DAMPERS FROM AIR
DE3507617A1 (en) METHOD FOR PURIFYING THE EXHAUST GAS FROM CLAUS PLANTS AND RECOVERING THE SULFUR COMPOUNDS CONTAINED IN THESE EXHAUST GAS
DE2621153A1 (en) Hardening sand cores by cold box process - where catalyst is reclaimed from carrier gas after use
DE4225436C1 (en) Catalytic hardening of sand mould elements - with two-stage sepn. and removal of amine(s) and solvents from exhaust air
EP0379741B1 (en) Method for hardening shaped articles, especially casting moulds and cores made of moulding sand
DE4007798C1 (en) Hardening sand mould members - comprises mixing catalyst with carrier gas, mixing with sand, pressing sand, retrieving gas and hardening
DE4218964A1 (en) Process for the treatment of water-based paint coagulate or filtrate
DE3627875A1 (en) Process and apparatus for separating off and returning volatile solvents
KR101488305B1 (en) Method and apparatus for recovering hardening catalyst of manufacturing process of core
DE2116958A1 (en) Air purification - for removal of toxic dusts and water soluble and insoluble condensible materials
DE907928C (en) Multi-stage deep-freeze washing process for cleaning raw gases rich in carbonic acid
EP0316682A1 (en) Process for the detachment of incrustations in moist eliminators
WO2004020333A1 (en) Method for recovering nitrogen from air
AT98974B (en) Method and apparatus for the recovery of volatile solvents.
DE397262C (en) Method and device for the recovery of volatile solvents by absorption
DE2047359C3 (en) Method and device for the separation of gaseous impurities from a gas mixture
DE2550588B1 (en) Method and device for hardening sand mold bodies
DE2747109A1 (en) METHOD FOR CONDUCTING A REACTION IN MOLD OR CORE MATERIALS AND DEVICE FOR PRACTICING THE METHOD

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH ES FR GB IT LI SE

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): AT BE CH ES FR GB IT LI SE

17P Request for examination filed

Effective date: 19891115

17Q First examination report despatched

Effective date: 19900927

ITF It: translation for a ep patent filed

Owner name: BARZANO' E ZANARDO ROMA S.P.A.

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH ES FR GB IT LI SE

REF Corresponds to:

Ref document number: 62839

Country of ref document: AT

Date of ref document: 19910515

Kind code of ref document: T

ET Fr: translation filed
GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19940824

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19940826

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19940830

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19940831

Year of fee payment: 7

Ref country code: BE

Payment date: 19940831

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 19940929

Year of fee payment: 7

EAL Se: european patent in force in sweden

Ref document number: 88115750.7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19950901

Year of fee payment: 8

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19950924

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19950925

Ref country code: ES

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 19950925

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Effective date: 19950930

Ref country code: CH

Effective date: 19950930

Ref country code: BE

Effective date: 19950930

BERE Be: lapsed

Owner name: DAIMLER-BENZ A.G.

Effective date: 19950930

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19960531

EUG Se: european patent has lapsed

Ref document number: 88115750.7

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19960924

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19960924

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 19990601

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050924