Solid material comminution or disintegration – Apparatus – With separation or classification of material
Patent
1986-08-29
1987-09-01
Rosenbaum, Mark
Solid material comminution or disintegration
Apparatus
With separation or classification of material
241101D, 241186A, 2411861, 241189R, B02C 13286
Patent
active
046903399
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a hammer mill with a grinding chamber, a rotor with hammers or beaters for size reduction of coarse material and an apparatus for feeding coarse material and discharging the product of reduced size.
STATE OF THE ART
In hammer mills of said type, the rotor generally turns in the grinding chamber about a horizontally arranged axis while the feed is effected in the top zone of the grinding chamber. A breaker plate in the form of a screen sleeve is generally provided at least in the lower part of the grinding chamber, through which the product of reduced size comes into a collecting compartment enclosing the grinding chamber and/or the screen sleeve and is discharged therefrom. Such hammer mills have high energy requirements as the product of reduced size can only pass with difficulty through the screen sleeve, is needlessly carried along and passes repeatedly through the grinding chamber.
SUMMARY OF THE INVENTION
The object of the invention is to provide a hammer mill of said type which allows size reduction with significant energy savings and a high efficiency.
This object is achieved according to the invention in a hammer mill of said type by the features set forth in the claims.
The invention is based on the insight that in a hammer mill the material fed into the grinding chamber already undergoes size reduction after a very short grinding path. When the feed material is first struck by the hammers, a substantial size reduction mostly takes place, whereafter the product of reduced size circulates needlessly with the rotor until it can go out through the screen sleeve.
The hammer mill according to the invention is advantageously provided with several inlets and outlets distributed uniformly over the periphery of the grinding chamber so as to be able to ensure uniform loading of the rotor, also when the direction of rotation of the rotor is reversed to provide for utilization of the hammers or beaters on both sides.
The supply ducts are preferably arranged so that the coarse material is supplied to the grinding chamber in different horizontal planes, so as to thereby further allow full uswe of the rotor height.
Thanks to the horizontal arrangement of the grinding chamber with a vertical rotor axis according to the invention, it is possible to arrange a great number of supply and discharge ducts distributed in a particularly simple and advantageous manner over the periphery of the grinding chamber, whereby the material supplied from above may be easily fed in radially. As each supply duct is associated with a discharge duct which is arranged at a relatively short distance behind this supply duct, the material fed in via each supply duct can, directly after undergoing size reduction on impingement of the hammers or beaters, be directly discharged from the grinding chamber as a product of reduced size via the discharge duct corresponding to the next outlet. The product of reduced size is thus no more carried along needlessly, as hitherto in the grinding chamber.
By the special arrangement according to the invention, the hammer mill is subdivided peripherally into a more or less great number of consecutively arranged mill segments, each defined by an inlet with the corresponding supply duct and by an outlet with the corresponding discharge duct arranged adjacent thereto at a short distance therefrom, the rotor carrying the hammers or beaters being associated in common with all of these mill segments.
The outlets provided according to the invention may be completely free or may possibly be covered selectively with screens having various hole sizes, so as to allow preselection of the size of the discharged product. Two or more such screens may be very simply arranged on a common slide which may be displaced so that the corresponding outlet is either kept completely free, or is selectively covered by one of the screens.
An embodiment of the invention will be described by way of example with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
REFERENCES:
patent: 1711464 (1929-04-01), Ruprecht et al.
patent: 2155697 (1939-04-01), Young
patent: 4273294 (1981-06-01), Hollely et al.
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