Solid material comminution or disintegration – Apparatus – Including means applying fluid to material
Patent
1996-01-05
1998-02-10
Husar, John M.
Solid material comminution or disintegration
Apparatus
Including means applying fluid to material
241 79, 241122, B02C 1710
Patent
active
057160155
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a ring roller mill which comprises at least one grinding ring and at least one roller, which crushes material against the inner periphery of the grinding ring. Such a mill can, for example, be used in connection with the manufacture of cement for grinding of mineral clinker materials, slags, and similar materials.
EP-A-0486371 discloses a ring roller mill in which conveyance of material is accomplished by the feed material being charged to a compartment before the grinding path where it is subjected to centrifugal action, whereafter the material is carried in an airstream axially through the mill. The grinding ring in this mill is rotating at a supercritical speed, and it is therefore necessary to mount scrapers internally in the ring in order to release the material during passage transversely to the grinding ring. These scrapers can be tilted so that they guide the material forward along the roller in the flow direction. After the passage through the grinding path, a coarse fraction is extracted from the bottom of the mill and passed through a screen, and from the top of the mill a fine fraction is directed to a separator. There is no internal recirculation in this mill, and the fractions which pass through the mill without being sufficiently ground are recirculated externally.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a ring roller mill with an effective internal conveying system, thereby eliminating the need for any external conveyance of overflow material, and thus producing substantial operational and plant design savings, not just because of the omitted conveyors, but also because the ring roller mill itself can be mounted directly at the ground level, hence eliminating the need to mount it at an elevated level to ensure proper discharge.
According to the invention, a ring roller mill comprising at least one grinding ring and at least one roller is characterized by at least one outlet opening for material suspension provided within, and offset radially from, the axis of, the grinding ring; by at least one air inlet opening on each side of the outlet opening in the rotational direction of the grinding ring, at least one axial end of the grinding ring being fitted with a collecting jacket which constitutes an extension of the grinding ring and with a stationary end section; by radially inwardly directed scoop plates fitted at intervals around the collecting jacket; and by means for rotating the collecting jacket at a speed below the critical speed (as herein defined).
The jacket collects the material which passes axially out of the grinding ring, e.g. over a dam ring and by means of the scoop plates the material is lifted around with the collecting jacket. Since the speed of the jacket is lower than the critical speed, i.e. the speed at which the material is not detached from the jacket, but is carried along all the way, the material will drop off from the uppermost part of the jacket and be dispersed towards the bottom of the latter, whereafter it is returned to the grinding path.
At several locations in the collecting jacket, guide plates which guide the dropping material towards the grinding track may be fitted internally in the mill and/or the dropping material may be blown towards the grinding track via air from the air inlet openings through which the feed material is introduced to the mill.
The angle v between the surface of the scoop plates and the tangent to the periphery of the ring upon which the plates are mounted may be varied (0.degree.<v<180.degree.). The optimum location and profile of the scoop plates will depend on the speed of the ring and on the types of materials being ground in the mill.
In a special embodiment of the ring roller mill, the scoop plates are more or less backwardly inclined relatively to the rotational direction, so that the collected material is prevented from sticking to the scoop plates instead of dropping back towards the grinding path.
Thus, it would be p
REFERENCES:
patent: 1220155 (1917-03-01), Fraser
patent: 1693247 (1928-11-01), Molz
patent: 1831625 (1931-11-01), Hardinge
patent: 1938045 (1933-12-01), Schmidt
patent: 3537658 (1970-11-01), JurgenJanich
patent: 3614002 (1971-10-01), Dore
patent: 5649667 (1997-07-01), Folsberg
F.L. Smidth & Co. A/S
Husar John M.
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