CA2022769A1 - Method of reconditioning foundry sand - Google Patents

Method of reconditioning foundry sand

Info

Publication number
CA2022769A1
CA2022769A1 CA002022769A CA2022769A CA2022769A1 CA 2022769 A1 CA2022769 A1 CA 2022769A1 CA 002022769 A CA002022769 A CA 002022769A CA 2022769 A CA2022769 A CA 2022769A CA 2022769 A1 CA2022769 A1 CA 2022769A1
Authority
CA
Canada
Prior art keywords
sand
neutralization
regeneration
value
per
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.)
Abandoned
Application number
CA002022769A
Other languages
French (fr)
Inventor
Hermann W. Sommer
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.)
SAZ SOMMER ALUMINIUM ZUG AG
Original Assignee
SAZ SOMMER ALUMINIUM ZUG 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 SAZ SOMMER ALUMINIUM ZUG AG filed Critical SAZ SOMMER ALUMINIUM ZUG AG
Publication of CA2022769A1 publication Critical patent/CA2022769A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C5/00Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
    • B22C5/18Plants for preparing mould materials
    • B22C5/185Plants for preparing mould materials comprising a wet reclamation step
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C1/00Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/16Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Processing Of Solid Wastes (AREA)
  • Treatment Of Sludge (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Abstract

A B S T R A C T

The invention relates to a process for reconditioning mono or mixed foundry sand containing organic and/or inorganic binders, where the sand containing organic binder after a thermal regeneration or the sand containing inorganic binder after a thermal and mechanical regeneration is neutralized with a suitable base or acid depending on its pH-value determined after regeneration by a measuring procedure, so that it subsequently has a pH-value between 6 and 8.

Description

20227~9 ~ 1-.
Method of reconditioning foundry sand .
S .
.;:

10 The invention relates to a method for reconditioning foundry sand.

The wet, mechanical, thermal or combined regeneration of foundry sand such as quartz sand, olivine, zircon, chromite sand and the like having organic or inorganic binders is known. The goal of such regeneration processes is to 15 provide a reconditioned sand which can be re-used instead of or as new sand. At the same time, substances in the foundry sand hazardous to the environement are to be elirninated by regeneration. Sand bound organically - usually only needs to be regenerated thermally, if it does not contain basic, acidic or other disturbing components, which do not combust or vaporize.

Mono-sand or mixed sand bound inorganically, in particular sand originally ;
treated with bentonite must be thermally and mechanically regenerated to produce a~sand which can be re-used. ;

A disadvantage of these known methods, for example for organic binder `
systems ~ with ~basic or acidic components which are difficult or impossible to eliminate and in particular ` for mono-sand or rnixed sand with inorganic bindersj is that the regenerate sand has properties which deviate from new `;; ~ -sand, for example the pH-value,~ the electrical conductivity, the degree of ~;~; 30 o~iithization, the sludge content and ~ the like. The properties of such re- ;~ ~ -; `gènerate `sand ~ are ~more ,or~ ~less ~disadvantageous especially !for reuse in making~ cores. The poorer properties of such regenerate sand apply particu-larly in it~ use ~as core sand with~ a synthetic resin binder and cause reduced rigidity, reduced processing time of the sand mixtures, increased consumption 35 ~ of binder and the like.
:
The object of the present invention is to provide a process of the above 20227~9 . 2 ~

described type, with which thermally and/or mechanically regenerated sand can be treated so that subsequently it is like new sand or similar to it.

This object is solved according to the invention in that sand containing an S organic binder after thermal regeneration or sand containing inorganic binder after a thermal and mechanical regeneration is neutralized with a suited base or acid depending on its pH-value determined after regeneration by a measuring procedure, for example by titration, so that subsequently it has a pH-value between 6 and 8.

Further embodiments of the process are given in the subclaims.

The essence of the invention is then to additionally wet-neutralize and purify the sand grains such as quartz grains for example originally treated with organic and/or inorganic binders (bentonite) after a thermal treatment and a subsequent mechanical purification, in particular to bring its pH-value and its electrical conductivity to the corresponding values of new sand.

The organic binder is extensively combusted or the inorganic binder, for example clay or bentonite, is dead-burned by the thermal and mechanical treatment and substantially extracted and separated from the sand grains by the mechanical purification. According to the invention, the regenerate sand is subsequently neutralized in the wet state in containers and purified. The mi~ture is stirred or turned in the treatment vessel to support and accele-rate the process.

The necessary amounts of neutralization additives can be advantageously deterrnined by titration of 50 to 100 g of a sand sample, namely when the sand is in its thermal or possibly its mechanical regeneration state.
~ , ! i ,! ~ , Experiments have shown surprisingly that a certain turbidity of the aqueous solution arises when adding a suitable acid as the neutralizer to regenerate `~
sand which was bound inorganically. Apparently a slight separation of dirt or sludge or binder still adhearing to the sand grains is caused by the neutra-lization Thus a possible electrostatic binding and adhesion of the grains is also eliminated.
,:
2~22~9 - 3 -After the neutralization and optionally a washing and subsequent drying, the treated sand when observed under the m~croscope already has a clearly cleaner appearance than before and has properties which are the same or S similar to new sand as is shown in the following examples I and II.

Example I

Quartz sand regenerate: AFS 60.3 Proper~,r Initial Neutral~zation with Comparable new sand regenerate 10 ml conc.
sand H2S04 per kg . . :
pH-value 9.6 7.4 ca. 7.0 Electrical sonductivity in ,uS/cm 172 4 ca. 0 Red heat loss (%) 0.17 0.14 ca. 0 Sludge content ~o 1.04 0.34 ca. 0.3 De~ree of oollthization 0.93 0.79 ca. 0 .
Example Il ~ ~

Quartz sand regenerate: AFS 45 ~ -:: :
1 ~oper~r Initial Neutralization with 12 ml ~- - -regenerate sand NH40H (25 ~o) per kg sand ~ ~
~ ~ .
pH-valué 3.6 ` 7.2 ;`
Electrical conductivity in ,uS/cm 189 12 `: . ',` '~

2 ~2 27 ~ 9 4 A neutralization of regenerated sand is illustrated in the attached drawing.

The sand already regenerated is fed to a neutralization vessel 3 from a sand supply 1 over a belt weigher for adjusting the weight per charge. ~long with 5 the supply of sand, a neutralization solution is pumped out of a storage container 4 by a pump 5 into the neutralization vessel 3 which is controlled by a fill level display (not shown). A stirring or turning of the material takes place in the vessel 3 by schematically illustrated stirring means during the filling process and during neutralization. After neutralization, the 10 solution is drawn through a filter plate 6, a pump 7 and a filter 8 and fed back to the storage container 4. A refreshing of the used neutralization solution with wash or fresh water and the addition of new acid or base takes place by means of a container 16. After neutralization, a washing and purification of the neutralized regenerate takes place by introducing a 15 washing solution from the storage container 13 into the vessel 3 when the stirring process is continued. The sand-wash water mL~Lture is then pumped out of the vessel 3 by a pump 9 into a cyclone 10. The sand and sludge-con-taining water separate in the cyclone 10. The sludge water is purified in a filter 12 and fed back to the storage container 13 by a pump 11. Fresh 20 water is added here to the used washing water. The separated, purified and neutralized sand from the cyclone 10 is dried by means of a swing drier 14 and then transported to a storage bunker 15.

The neutralization and washing or purification take place alternatively in two 25 respectively closed circulation systems. To adjust the neutrality of the washing solution, bases can also be added for example when neutralizing with an acid or also vice versa. The belt weigher can also fill several neutrali~
zation vessels by means of a distributor belt, where also several cyclons can be employed-The neutralization and purification processes are performed in closed cycleswith the least possible amount of water consumption for environmental reasons. The neutralization solution after the completed reaction is drawn out of the vessel together with the extracted sludge fraction and subse-35 quently passed through a filter to separate the sludge material. When neces-sary, the filtered and used neutralization solution is refreshed with new ;, ~. ,~

2~227~9 5-acid or base and with fresh water or wash water and is always fed back in the cyclic process for the next treatment, for example by means of an inter-mediate container.

S A further exarnple is shown in the following of a mixed sand bound inor-ganically, where the initial old sand is thermally and mechanically prepared to give regenerate sand and it is subsequently neutralized and purified.

A strength test is made on particularly sensitive cold-box core sand mixtures 10 at various stages of treatment compared to new sand.

~ 2022759 Example III

Mesh Bentonite Therm.-mech. regen. Neutral. with 10 ml conc.
analysis old sand sand from I H2S04 per kg sand from I
s II III
_ _ % % %
0.71 mm 0.2 0 0.1 0.5 mm 0.5 0.7 0-9 0.355 mm 3.6 6.1 5.7 0.25 rnm 25.1 22.3 21~5 0.18 mm 52.B 48.0 50.2 0.125 mm 14.2 21.0 20.0 0.09 mm 3.3 1.8 1.5 0.063 mm 0.3 0.1 0.1 -0.02 rnm 0 0 0 20.02 mm 0 0 0 -pH-value 9.8 9.7 7.1 ~ -Electr. con- -ductivity in,uS/cm 976 165 3 -~
Sludge % 8.26 0.93 0.32 ~ ;-Red heat ~ ~
loss % 2.57 0.17 0.14 ~ ~;
Oolith. degree 2.3 0.89 0.77 Comparison of flexural strength inl N~cm~ on cold-box sand samples~

` ` sand mixture: 30 ~o new sand, AFS about 60 70 ~o therm.-mech. regenerate 35 0.8 % synthetic resin 352 T 14 0.8 % synthetic resin 652 TEA 700 ~` 2~22769 7-Test time Sand IISalld III 100 new sand S :

1/2 h lgS 390 340 h 190 420 410 2 h 192 440 420 ~ ~ -24 h 225 450 460 ~ ~

; ~:
-.

.

Claims (11)

1. Process for reconditioning mono or mixed foundry sand containing organic and/or inorganic binders, c h a r a c t e r i z e d i n t h a t the sand containing organic binder after a thermal regeneration or the sand containing inorganic binder after a thermal and mechanical regene-ration is neutralized with a suitable base or acid depending on its pH-value determined after regeneration by a measuring procedure, so that said sand subsequently has a pH-value between 6 and 8.
2. Process of claim 1, characterized in that the pH-value of the sand lies between 6.8 and 7.5 after neutralization.
3. Process of claim 1, characterized in that the sand is subjected to wet purification and subsequent drying after neutralization.
4. Process of claim 1, characterized in that for neutralization NH4OH is used as the base or sulphuric acid or hydrofluoric acid is used.
5. Process of claim 1, characterized in that for neutralization concentrated sulphuric acid in an amount of 3 to 50 ml per kg sand is added to the sand which is basic after regeneration.
6. Process of claim 1, characterized in that for neutralization concentrated sulphuric acid in an amount of 8 to 12 ml per kg sand is added to the sand which is basic after regeneration.
7. Process of claim 1, characterized in that for neutralization 3 to 40 ml of 25 % NH4OH per kg sand is added to the sand which is acidic after regeneration.
8. Process of claim 1, characterized in that for neutralization 12 ml of 25 % NH4OH per kg sand is added to the sand which is acidic after rege-neration.
9. Process of claim 1, characterized in that the neutralization and purifi-cation are performed in a closed circulation system and alternatively in a single vessel.
10. Process of claims 1 or 6, characterized in that the neutralizing solution after use is purified by filtration and used again in the neutralization process after being refreshed with washing water.
11. Reconditioned foundry sand obtainable in that it is treated thermally and/or mechanically depending on the binder contained therein and thereafter neutralized so that its pH-value lies between 6.8 and 7.5.
CA002022769A 1990-02-14 1990-08-07 Method of reconditioning foundry sand Abandoned CA2022769A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4004553A DE4004553C1 (en) 1990-02-14 1990-02-14
DEP4004553.6 1990-02-14

Publications (1)

Publication Number Publication Date
CA2022769A1 true CA2022769A1 (en) 1991-08-15

Family

ID=6400137

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002022769A Abandoned CA2022769A1 (en) 1990-02-14 1990-08-07 Method of reconditioning foundry sand

Country Status (15)

Country Link
EP (1) EP0446402A1 (en)
JP (1) JPH03238141A (en)
KR (1) KR910015345A (en)
CN (1) CN1054021A (en)
BR (1) BR9003152A (en)
CA (1) CA2022769A1 (en)
CS (1) CS219190A2 (en)
DD (1) DD297087A5 (en)
DE (1) DE4004553C1 (en)
DK (1) DK149890A (en)
FI (1) FI902822A7 (en)
HU (1) HUT58008A (en)
NO (1) NO902410L (en)
PL (1) PL285083A1 (en)
PT (1) PT94164A (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4129863A1 (en) * 1991-09-07 1993-03-11 Hanf Carl Elino Ind Ofenbau Bentonite bound foundry moulding sand conditioning process - by heat treatment of precleaned sand for high quality sand useful for core prodn.
DE19927107A1 (en) * 1999-06-14 2000-12-21 Fischer Georg Gmbh & Co Kg Device to reduce odorous emissions from a casting installation has a container for bio catalysts and/or enzymes and active region in which the bio catalysts and/or the enzymes interact with the substances causing the odorous emissions
EP1222978A3 (en) * 2001-01-15 2007-10-17 Sintokogio, Ltd. A method for making sand covered with bentonite, the sand, and a method for recycling molding sand for a mold using the sand covered by bentonite
DE102007027298A1 (en) * 2007-06-11 2008-12-18 Maschinenfabrik Gustav Eirich Gmbh & Co. Kg Process for the treatment of foundry sand
CN102059319B (en) * 2011-01-19 2012-12-19 昆明理工大学 Joint regeneration method for old resin sand
CN102500458B (en) * 2011-11-28 2014-07-09 河海大学 Sand washing method and special device thereof
CN102615243B (en) * 2012-03-27 2013-09-18 华中科技大学 Foundry used sand wet intermittent regeneration method and equipment thereof
JP2016147287A (en) * 2015-02-12 2016-08-18 マツダ株式会社 Casting sand regeneration process, and polishing device
ES2874204T5 (en) * 2018-06-29 2024-10-07 Nemak Sab De Cv Procedure for preparing a foundry sand mixture
JP7142563B2 (en) * 2018-12-26 2022-09-27 伊藤忠セラテック株式会社 How to recycle recovered sand
EP3797896A1 (en) * 2019-09-27 2021-03-31 Finn Recycling OY Cleaning sand used at foundry

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US414388A (en) * 1889-11-05 emmens
DE2233111C3 (en) * 1972-07-06 1974-11-28 Hermann 2105 Seevetal Jacob Method and device for the regeneration of synthetic resin-bonded foundry sand
US4113510A (en) * 1974-06-07 1978-09-12 Societe D'applications De Procedes Industriels Et Chimiques S.A.P.I.C. Process for regenerating foundry sand
CA1050209A (en) * 1974-12-16 1979-03-13 Julius M. Bleuenstein Sand reclamation and purification
JPS5292823A (en) * 1976-02-02 1977-08-04 Hitachi Ltd Old sand cleaning reproduction process
DE2656672C2 (en) * 1976-12-15 1978-09-21 Daimler-Benz Ag, 7000 Stuttgart Procedure for regenerating core sand
CH631643A5 (en) * 1978-04-14 1982-08-31 Fischer Ag Georg METHOD FOR REGENERATING OLD FOUNDRY SAND AND DEVICE FOR CARRYING OUT THE METHOD AND PRODUCT OF THE METHOD.
US4401638A (en) * 1981-12-21 1983-08-30 Materias Primas, Monterrey, S.A. Process for purifying silica sand
GB8317669D0 (en) * 1983-06-29 1983-08-03 British Ind Sand Ltd Chemical treatment of sand
US4685973A (en) * 1984-02-03 1987-08-11 Steel Castings Research And Trade Association Reclamation of foundry sands

Also Published As

Publication number Publication date
FI902822A0 (en) 1990-06-06
PT94164A (en) 1991-09-30
DE4004553C1 (en) 1991-10-10
DK149890A (en) 1991-08-15
HU903815D0 (en) 1990-11-28
CS219190A2 (en) 1991-09-15
CN1054021A (en) 1991-08-28
DD297087A5 (en) 1992-01-02
HUT58008A (en) 1992-01-28
KR910015345A (en) 1991-09-30
JPH03238141A (en) 1991-10-23
PL285083A1 (en) 1991-10-07
BR9003152A (en) 1991-11-12
EP0446402A1 (en) 1991-09-18
NO902410D0 (en) 1990-05-31
DK149890D0 (en) 1990-06-19
FI902822L (en) 1991-08-15
NO902410L (en) 1991-08-15
FI902822A7 (en) 1991-08-15

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Legal Events

Date Code Title Description
FZDE Discontinued