Solid material comminution or disintegration – Apparatus – Including means applying fluid to material
Reexamination Certificate
1998-12-15
2001-01-30
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Apparatus
Including means applying fluid to material
C241S228000
Reexamination Certificate
active
06179233
ABSTRACT:
TECHNICAL FIELD
The present invention relates to wet crushing and to crushers comprising at least one roller travelling over a circular track and elastically pressed against the latter.
BACKGROUND ART
Known crushers of the type defined above, a vertical crusher or ring crusher, in which a multi-granular layer of materials for crushing is compressed between the roller and the track with sufficient pressure to crush the grains and cause their fragmentation to smaller grains, are not suited to wet crushing as an excessive water content in the materials for crushing reduces their efficiency. In wet crushing, the materials for crushing generally have a water content of 10% to 60% by weight, with an average of 30%, which is incompatible with good crushing efficiency.
The object of the present invention is to permit the rational use of crushers of this type for wet crushing.
SUMMARY OF THE INVENTION
The process according to the present invention includes in subjecting the materials for crushing to several crushing operations by crushing in a layer or bed of materials and, during their dwell time in the crushing apparatus, and between two successive crushing operations, in adding water or another liquid to the materials to re-expand the layer of materials and to enable the progress of the materials through the crushing apparatus to be controlled and, possibly, to enable their grain size grading to be ensured, and then in draining the materials and/or removing moisture therefrom so as to reduce their water content to less than 20% by volume. The draining and moisture removal operations are carried out inside the crushing apparatus, which is arranged for this purpose, which makes it possible to achieve a considerable reduction in the cost of the plant by avoiding the use of auxiliary apparatus and means of transport between the different apparatus.
For the purpose of implementing the invention, use will be made of a crusher comprising a circular track, fictitiously divided into several track elements, or circular tracks, spaced apart from one another, where the successive crushing operations will be carried out, means for transferring the materials from one track or track element to the next, means for projecting water or another liquid onto the materials during their transfer from one track or track element to the next, and means suitable for ensuring the draining of the materials and/or removal of moisture therefrom prior to their next passage beneath the roller. In a ring crusher having a horizontal axis, the tracks will be disposed side by side.
The addition of water or of another liquid to the materials after each crushing operation makes it possible, on one hand, to improve the flow of the materials and their distribution in a layer of uniform thickness over the track, and, on the other hand, to remove the fine particles immediately after their production, which makes the subsequent crushing operations more efficient.
The water or any other liquid can be projected onto the materials when they are still on the track, for example by means of nozzles supplied under pressure which then constitute one of the means for transferring the materials from one track or track element to the next. In particular, when the crusher is of the rotary ring type and is driven in rotation at a speed greater than the critical speed so that the centrifugal force is sufficient to maintain a layer of materials over the entire periphery of the track provided on the ring, use can be made of nozzles placed inside the ring, in its upper portion and on the rising side, and the jets of which will be directed towards the track to detach the materials; the action of the jets can be supplemented by that of a scraper. Moisture removal can be effected through the action of the centrifugal force in the portion of the track located upstream of the crushing roller. A pre-compression roller can be provided on the track, immediately ahead of the crushing roller, to ensure complementary moisture removal by pressure.
According to a preferred form of embodiment of the invention, the crusher is of the rotary ring type and the material feed device comprises one or more baffle or deflecting plates arranged so as to intercept the materials detached from the track provided inside the ring and orientated so as to deflect them in a direction having a component parallel to the axis of the ring; additional water spraying means can be provided above the deflecting plate or plates to facilitate the flow of the materials. Alternatively, the deflecting plate or plates can be porous, and water or another liquid can be injected through the plate(s) to create a liquid film facilitating the flow of the materials. The deflecting plate or plates can comprise an upper screening surface and means for collecting and discharging the water and the fine crushed products that pass through this surface; they then constitute a means for draining the coarse materials. They can be flat or curved, and each plate will be orientatable about a horizontal axis, and possibly inclinable about a vertical axis, so as to be able to adjust the feeding speed of the materials for crushing and choose the point at which the materials deflected by the plate(s) fall back onto the track. The removal of moisture from the materials is carried out, through the action of the centrifugal force, in the area of the track located between the point at which the materials deflected by the deflecting plate or plates fall back onto the track and the roller. Preferably, this area will have an angular extent of at least 30°.
In the event of the track being formed inside a drum with a horizontal axis and of supply and discharge areas being arranged on either side of the track, drainage means can be provided in these areas to facilitate discharge of the water. For the same purpose, when the track is constituted by protection plates resting on the shell of the drum, which is generally the case, drainage means can be provided under the plates, in the crushing area. A grooved roller can also be used. At its ends, the drum will be provided with annular barrier-forming rims the inside diameter of which will be chosen to retain the material within the supply and discharge areas, respectively, while, at the same time, possibly enabling the water to be discharged by overflowing. These rims can be designed in such a way that is possible to change their inside diameter in order to adjust their height (radial dimension). The materials retained by these rims form, at least at the crushing area, a bank that prevents the materials compressed between the roller and the track from being expelled laterally by the pressure while, at the same time, enabling the water to be discharged partially through the said bank, if the supply area, or discharge area, respectively, is provided with drainage means, and partially by overflowing the bank.
A rotary screen, having a horizontal axis, can be placed at the crusher output to sort the crushed products. The rejects of the rotary screen can be returned to the track or to the crusher input by an internal recycling device comprising a conduit disposed inside the crusher, transversely to the track, means for supplying the said conduit with the screen rejects and, possibly, means for facilitating the flow of the rejects through the conduit. The screen can be integral with the body of the crusher or supported and driven by individual means. Water injection means can be provided in the rotary screen to facilitate discharge of the crushed products and possibly reconstitute with them a pulp of a composition suitable for subsequent processing.
According to a first alternative form of embodiment, the crusher comprises two tracks spaced axially from one another inside a drum with a horizontal axis, two rollers, each suitable for travelling over a track, means for bringing the materials for crushing into the drum, between the two tracks, and means for discharging the crushed materials at the two ends of the drum.
According to another alternative form of embodiment, the crushe
Cordonnier Alain
Gaucherand Bernard
FCB Societe Anonyme
Harrison & Egbert
Rosenbaum Mark
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