Classifying – separating – and assorting solids – Precedent preparation of items or materials to facilitate...
Reexamination Certificate
1999-12-10
2001-07-24
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Precedent preparation of items or materials to facilitate...
C241S019000, C209S139100, C209S142000, C209S138000, C209S039000, C209S012100
Reexamination Certificate
active
06264038
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns a method for processing waste with multistage air classification of light fractions from dried material, as well as a device to implement this method.
The organic material groups in waste are fractions of high calorific value from which fuels may be obtained. The organic material groups consist essentially of light (dispersible) and heavy (granular) fractions which may then be sorted, depending on waste source and application, into coarse (approx. <10 mm), fine (approx. >2 mm-10 mm) and superfine (<2 mm) fractions.
In order to obtain pollutant-free, i.e. the cleanest possible fuels from waste, it is necessary to separate the waste, after suitable pretreatment, into specific material groups and separate out the organic fractions of high calorific value. This is usually achieved using air-classification equipment.
Methods of this kind are described, among others, in
DE-PS 31 05 597
FP-PS 02 43 747 B1
U.S. Pat. No. 4,623,515
U.S. Pat. No. 4,815,668
To separate out the light organic fractions, the known methods require a combination of upstream screening before air classification in order to achieve a sufficiently high degree of separation between the light and heavy particles through air classification of the sorted particle-size groups. Air classification of all particle sizes together results in insufficient degrees of separation. This combined procedure is relatively complex and entails high installation costs of technical implementation.
The task of the invention is to avoid the disadvantages described of high technical complexity and cost for the air classification of light fractions from the waste mixtures and to simplify the air classification process.
SUMMARY OF THE INVENTION
This invention fulfills this task by subjecting the material to be air-classified to the preliminary steps of precomminution, ferrous-metal separation, postcomminution and drying, and subsequently moving it into two or more cascading, sequentially-arranged air classification stages through which it passes sequentially.
The air speeds of the individual air classification stages are individually adjustable so that, appropriately, the first air-classification stage has the lowest air speed and the last air-classification stage, the highest. This arrangement and adjustment of the systems facilitates the process in which, as the material passes through the air-classification stages sequentially, first the fine light fractions, and in the subsequent stages, the coarser light fractions are separated out.
The heavy, nondispersible and granular material fractions pass downward through all air-classification stages and are discharged at the bottom. They then undergo an additional density separation and are separated into a high-calorific-value organic fraction and an inorganic mineral fraction.
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Baker, Jr. Thomas S.
R.S.T. Luxembourg SA
Schlak Daniel K
Walsh Donald P.
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