Solid material comminution or disintegration – Apparatus – Loose grinding body comminutor
Patent
1996-10-04
1997-11-25
Husar, John M.
Solid material comminution or disintegration
Apparatus
Loose grinding body comminutor
241183, B02C 1722
Patent
active
056902859
DESCRIPTION:
BRIEF SUMMARY
SUBJECT OF THE INVENTION
The present invention relates to a lining element intended to be part of the lining of the internal wall of the shell of a rotary mill. The latter is filled with grinding media. The lining element shows a smooth and cylindrical face on the lower or external side for matching the internal surface of the shell and a cylindrical face on the upper or external side. The invention also relates to a rotary mill that includes a cylindrical shell, the internal lining of which consists of such element.
State of the Prior Art
The invention relates at the same time to the mills for the wet process as to the mills for the dry process, specially those used in the cement or mining industry for crushing and grinding clinker, cement raw materials or ores. These mills consist of a cylindrical shell rotating around its longitudinal axis and containing a grinding charge made of grinding media, generally balls, but that can also be cylpebs, boulpebs or other media of different sizes. The material to be ground is introduced at one side of the mill and is ground and crushed between the grinding media, as it progresses towards the outlet, on the opposite side.
Given that the grinding occurs progressively throughout the mill, in the direction of throughput, the best grinding conditions are achieved when the size of the grinding media matches that of the material to be ground. In other words, the coarsest grinding media should preferably, be concentrated on the inlet side of the mill, whereas the smallest ones should be grouped together on the outlet side. This is known as the classification of the grinding media according to their size. Under optimum conditions, this classification should therefore be achieved automatically during the operation of the mill.
In order to achieve that classification, it is known to provide linings consisting of plates, the internal surface of which creates, in the mill, a succession of volumes in the shape of a truncated cone flared towards the inlet of the mill. In other words, the lining offers, in longitudinal cross-section, a saw-toothed profile. These inclined surfaces tend to push back the coarsest grinding media towards the inlet of the mill and, as a consequence, the smallest media towards the outlet. As a consequence, the size of the grinding media decreases as the fineness of the material to be ground increases.
By virtue of this classification of the grinding bodies in the mills, a reduction in the energy consumption in the range of 11 to 15% is achieved, which nowadays is significant.
Patent FR-A-2213808 already presents the idea of classifying the media by using a plate the shape of which offers undulations that make an angle with the generatrix of the mill. However, this patent necessarily combines the said undulations plate with another plate showing an external surface in the shape of a truncated cone. This means that the well-known principle of volumes in the shape of a truncated cone remains the basis of the classification for that patent.
Patent DE-B-1161110 describes a flat and undulated plate. However, this plate tries to recreate the shape of a truncated cone by having undulations of decreasing depth in the same plate. Moreover, the same patent does not mention the possibility of designing the undulations so that they show an angle with the generatrix of the mill. One should add that if the document in question also describes a transversal element, the latter offers a height that does not go above the maximum height of the undulations. That transversal element tends to reduce the tendency of the material of going back towards the inlet of the mill. It does not contribute to the classification, as indicated in col. 3, lines 13 ff.
Patent FR-A-2054238 mentions a "ring". However, the main purpose of the said ring is to slow down the speed at which the material proceeds towards the outlet while not disturbing the classification effect of the lining among which that ring is installed. It is true that, incidentally, imperfect classification can be reached
REFERENCES:
patent: 2801804 (1957-08-01), Frankert
patent: 3467321 (1969-09-01), Tkachev et al.
patent: 3630459 (1971-12-01), Slegten
patent: 3677479 (1972-07-01), Slegten
patent: 4200242 (1980-04-01), Ueda
patent: 4211370 (1980-07-01), Wilson
patent: 4289279 (1981-09-01), Brandt
patent: 4736894 (1988-04-01), Ferrada et al.
Husar John M.
Slegten Societe Anonyme
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