EP0074755B1 - Procédé pour la récupération de sables de fonderie - Google Patents

Procédé pour la récupération de sables de fonderie Download PDF

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Publication number
EP0074755B1
EP0074755B1 EP82304595A EP82304595A EP0074755B1 EP 0074755 B1 EP0074755 B1 EP 0074755B1 EP 82304595 A EP82304595 A EP 82304595A EP 82304595 A EP82304595 A EP 82304595A EP 0074755 B1 EP0074755 B1 EP 0074755B1
Authority
EP
European Patent Office
Prior art keywords
sand
energy
binder
reclamation
fluid
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.)
Expired
Application number
EP82304595A
Other languages
German (de)
English (en)
Other versions
EP0074755A1 (fr
Inventor
John Kenneth Potter
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.)
Unilever PLC
Unilever NV
Original Assignee
Unilever PLC
Unilever NV
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 Unilever PLC, Unilever NV filed Critical Unilever PLC
Publication of EP0074755A1 publication Critical patent/EP0074755A1/fr
Application granted granted Critical
Publication of EP0074755B1 publication Critical patent/EP0074755B1/fr
Expired 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
    • B22C5/10—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by dust separating

Definitions

  • This invention concerns the reclamation of foundry sands.
  • Foundry sand is used with suitable binding agents for making moulds and cores for casting metal.
  • Various binders both inorganic and organic, are used to bond the foundry sand and, for many years, the sand after use was discarded.
  • British Patent Specification No. 1,322,864 is also concerned with the problem of sand reclamation and discloses a process in which the used foundry sand is introduced into a blast of fluid under pressure, whereby the sand is projected against lateral walls of a hermetically sealed casing to cause a matrix of the binding agent to burst releasing the sand. The product of this process is then subjected to granulometric selection to remove the fines generated by the high impact.
  • British Patent Specification No. 1,505,904 discloses a process in which coated sand particles are projected in a current of gas against the interior surface of a rotating drum.
  • British Patent Specification No. 2,019,274 discloses a similar process in which, again, the coated sand is projected against a. solid target.
  • US Patent No 2 478 461 also discloses a process for the removal of binder from foundry sand, but appears to be mainly concerned with binders which generate a carbonaceous residue. It is suggested that this residue can be burned and the partially cleaned sand further cleaned by subjecting high velocity sand grains issuing from nozzles to severe erosive action and further suggests the provision of an abrasive-resistant lining (18).
  • This specification like other referred to earlier in which targets are specified, may well introduce contaminants from the target into the sand.
  • the essential problem to be overcome in the sand reclamation process is an adequate balancing of two objectives, namely the effective removal of a hard and tenacious coating and the avoidance of significant particle degradation of the clean sand particles to produce fines which are not useful in the reclaimed sand.
  • the present invention provides a process which effectively balances these two objectives.
  • the present invention provides a process for the reclamation of silicate binder coated foundry sand, in which the coated foundry sand is subjected to a fluid energy acceleration to remove the binder and the reclaimed sand is separated from the binder debris, characterised in that the fluid energy is imparted to the sand in a fluid energy mill to a sufficient extent to substantially remove the binder coating without causing significant disintegration of the sand particles and in which the energy imparted to the sand is less than 1,300 kilojoules per kilogramme of coated sand and in which the Reynolds Number arising from the energy-imparting jet stream does not exceed 6.5x10 4 .
  • the optimal energy range was from 400 to 1,200 kilojoules per kilogramme of sand.
  • This work was carried out in a microniser having a diameter of 10 cm and containing six 1.6 mm diameter inlet nozzles in the periphery of the chamber.
  • the feed rate of the sand varied from 0.33 to 1.54 per second and the optimum feed rate was of the order of 1 g per second for this apparatus.
  • the sand feed rate can be increased in relation to the size of the mill and air throughput.
  • the specific energy imparted to the sand should be of the same order of magnitude as previously defined but applied at a commercially useful sand feed rate.
  • Fluid energy or jet mills (alternatively known as Micronisers) suitable for use in the process of this invention are available from various suppliers in the market and are described in, for example, Chemical Engineering Handbook, Ed. J. H. Perry, 4th ed., McGraw Hill, p. 8-42 and 43.
  • Such mills consist essentially of a chamber in which the contaminated sand is acted upon by a number of gaseous fluid jets issuing through orifices spaced around the periphery of the substantially circular chamber.
  • the fluid energy imparted to the sand in the mill is determined by calculating the energy expended by the adiabatic expansion of the compressed fluid through the nozzles, and is given by:
  • the specific energy input is obtained by dividing by the feedrate of sand (kg/s), i.e.
  • Reynolds Number is the ratio of inertial force to the viscous force of the flowing fluid. It is a measure of the air fluid velocity in the jet stream which determines the drag force exerted on the individual particles and thus determines their acceleration and their impact velocity. Reynolds Number can be calculated on the basis of the fluid mass flowrate through a single nozzle (Q f ) of nozzle diameter, d " , viscosity
  • the Reynolds Number is in the range 4.Ox10 4 to 6.4x10 4 .

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Disintegrating Or Milling (AREA)

Claims (3)

1. Procédé pour la récupération de sable de fonderie enrobé de liant au silicate, dans lequel le sable de fonderie est soumis à une accélération par énergie fluide pour éliminer le liant et le sable récupéré est séparé des débris de liant, caractérisé en ce que l'énergie fluide est communiquée au sable dans un désintégrateur à jet d'air jusqu'à un degré suffisant pour éliminer sensiblement tout l'enrobage de liant sans causer de désintégration significative des particules de sable et dans lequel l'énergie communiquée au sable est inférieure à 1,300 kilojoules par kilogramme de sable enrobé et dans lequel le nombre de Reynolds découlant du courant du jet communiquant l'énergie ne dépasse pas 6,5×104.
2. Procédé selon la revendication 1, dans lequel l'énergie communiquée est de 400 à 1,200 kilojoules par kilogramme de sable et dans lequel le nombre de Reynolds est de 4x104 à 6,4x104.
3. Procédé selon l'une quelconque des revendications précédentes, dans lequel le sable récupéré est séparé des débris de liant dans un système de triage séparé.
EP82304595A 1981-09-03 1982-09-01 Procédé pour la récupération de sables de fonderie Expired EP0074755B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8126689 1981-09-03
GB8126689 1981-09-03

Publications (2)

Publication Number Publication Date
EP0074755A1 EP0074755A1 (fr) 1983-03-23
EP0074755B1 true EP0074755B1 (fr) 1986-01-15

Family

ID=10524292

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82304595A Expired EP0074755B1 (fr) 1981-09-03 1982-09-01 Procédé pour la récupération de sables de fonderie

Country Status (8)

Country Link
EP (1) EP0074755B1 (fr)
JP (1) JPS5853346A (fr)
AU (1) AU542894B2 (fr)
BR (1) BR8205096A (fr)
CA (1) CA1209784A (fr)
DE (1) DE3268559D1 (fr)
ES (1) ES8308242A1 (fr)
ZA (1) ZA826431B (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478461A (en) * 1946-03-16 1949-08-09 Nichols Eng & Res Corp Apparatus and method for treating foundry sand

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3088183A (en) * 1960-12-19 1963-05-07 Simpson Herbert Corp Apparatus for treating granular material
DE2408981C3 (de) * 1974-02-25 1979-11-08 Alb. Klein Kg, 5241 Niederfischbach Verfahren zur Reinigung von Schüttgütern durch Zentrifugalkräfte sowie Vorrichtung zur Durchführung des Verfahrens
GB1463749A (en) * 1974-08-21 1977-02-09 British Leyland Uk Ltd Apparatus for use in producing a fluidised bed of granular material
US3970547A (en) * 1975-05-22 1976-07-20 Raytheon Company Air classification apparatus
GB1493774A (en) * 1975-05-22 1977-11-30 Raytheon Co Materials separating apparatus
DE2921197A1 (de) * 1979-05-25 1980-12-04 Hermann J Linder Verfahren und vorrichtung zum regenerieren von giessereisand
GB2061770A (en) * 1979-10-27 1981-05-20 Futtans Ltd Improvements in or relating to the separation of granular mixtures

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478461A (en) * 1946-03-16 1949-08-09 Nichols Eng & Res Corp Apparatus and method for treating foundry sand

Also Published As

Publication number Publication date
AU542894B2 (en) 1985-03-21
JPS5853346A (ja) 1983-03-29
ZA826431B (en) 1984-04-25
CA1209784A (fr) 1986-08-19
AU8784582A (en) 1983-03-10
DE3268559D1 (en) 1986-02-27
ES515460A0 (es) 1983-08-16
BR8205096A (pt) 1983-08-09
EP0074755A1 (fr) 1983-03-23
ES8308242A1 (es) 1983-08-16

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