Classifying – separating – and assorting solids – Fluid suspension – Gaseous
Patent
1993-07-12
1995-06-06
Bidwell, James R.
Classifying, separating, and assorting solids
Fluid suspension
Gaseous
2091391, 209149, B07B 704
Patent
active
054214629
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates in general to an arrangement for the dry reconditioning of used foundry sands and in particular to an arrangement for the dry reconditioning of used foundry sands, in which said used sand containing binder covers and impurities and air of ambient temperature or an air/gas mixture heated to a maximum of 550.degree. C. can be supplied to a mechanical cleaning step in the form of a multi-cell separator and each separator cell having: an ascending pipe open at both ends; a precipitator arranged at a distance above and opposite the upper outlet opening of the ascending pipe having an axis and comprising surfaces decelerating and deflecting the used sand/air or used sand/gas/air jet; fan means for supplying said air or said air-gas mixture; feed means for feeding the sand and conveying the sand from one separator cell to the other separator cell, respectively; means for removing the sand from said separator; means for collecting and removing the resulting covering and impurity substances.
BACKGROUND AND FEATURES OF THE INVENTION
Such arrangements are known from DE-PS 28 56 536, DE-OS 39 09 535, EU-A1-00 60 394, U.S. Pat. No. 4,266,673 or DE-OS 22 33 111, for example.
As follows from DE-PS 28 56 536, the objective of these arrangements is not only to separate the binder covers from the sand grains but also to separate the sand from the isolated coverings and other impurities inside the arrangement and during the treatment. In the latter citation additional outlet openings for a secondary gas stream are arranged in a certain manner about the ascending pipe for this purpose so as to obtain a local limited uniform flow-through which acts in the same direction all around. The separation means used is an impingement plate arranged at a distance over the outlet opening of the ascending pipe. Several separator cells are disposed in a joint upper housing box, an outlet chamber being arranged above the impingement plate for each separator cell, into which chambers the gas leaving the impingement plate flows together with the separated particles of material. These chambers are connected to a joint exhaust-air collector. At a distance below the outlet opening of the ascending pipe each separator has a screen-like catch means developed in such a way that it conveys a partial stream of the sand stream coming down from the impingement plate in a veil-like manner to the next separator cell while the other partial stream is supplied back again to the inlet nozzle of the ascending pipe. On the whole, this arrangement is expensive and leaves a lot to be desired during sorting as regards the separating cut.
Another drawback consists in that great forces have to be expended for separating the binder covers, owing to which the sand grains are partially destroyed at the impingement plate and the sand grain structure is changed in undesired manner.
In order to reduce the expenditure, a special swirling step is assigned to the outlet end of the ascending pipe of the arrangement according to the above-mentioned laid-open print. By this the escaping air current is to expand partially radially by taking along impurities contained in the used sand so as to impinge on the mass of sand, dust and air, which falls down from the impingement plate, thus better removing the fines. In order to improve this effect, the impingement plate extends relatively far downwardly and is constricted at its lower outlet end. The separation of the binder covers from the sand grains is not improved by this.
The object of this invention is to further develop said initially mentioned arrangement in such a way that accompanied by a space-saving design both the separation of the binder covers from the individual sand grains and sorting can markedly be improved, so that the effectiveness of the reconditioning can markedly be increased in each separator cell, the sand grain structure being maintained as completely as possible.
This problem is solved by an arrangement for the dry reconditioning of used foundry san
REFERENCES:
patent: 4226673 (1981-05-01), Haidlen et al.
patent: 4257880 (1981-03-01), Jones
patent: 4260478 (1981-04-01), Hosokawa et al.
patent: 5120431 (1992-06-01), Cordonnier
Official Letter from the German Patent Office dated Mar. 5, 1992 (4 pages).
Translation of Official Letter from the German Patent Office Dated Mar. 5, 1992 (3 pages) See MPEP Sec. 609 at pp. 600-67,68 (Rev. 14 Nov. 1992).
Copy of Intl. Search Report cover sheet(?), 3 pgs. dated Oct. 19, 1992 (form PCT/ISA/220, Jul. 1992); and accompanying Search Report listing cited (Cont'd.) art, 3 pgs. dated Oct. 19, 1992 (Form PCT/ISA/210, Jul. 1992). See M.P.E.P. Sec. 609 at pps. 600-67,68 (Rev. 14 Nov. 1992).
Hofbauer Hermann
Muller Erich
Putzig Erhard
Schaarschmidt Ekart
Bidwell James R.
Kunkel-Wagner GmbH & Co. KG
Nguyen Tuan N.
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