LU81934A1 - IMPROVEMENTS ON GRINDERS - Google Patents

Description

DESCRIPTIVE MEMORY

FILED IN SUPPORT OF A REQUEST FOR

PATENT

FORMED BY

BA3COCK PRODUCT ENGINEERING LTD. for

Improvements to "grinders.

The present invention relates to "grinders and in particular a" grinder such that the fineness of the material reaching its outlet can be modified. The invention can be implemented in variants of the so-called type E grinder in which a circle of grinding balls is maintained and operates between two grinding rings which rotate relative to one another.

According to the invention, a "kype" mill is provided in which the material to be ground passes through a set of elements.

OlVL Λτττ -nr. / 1 OOIlO /Τ.ΤΓ5Γ crushing elements and the crushed material is entrained in a gas flow from the crushing elements to an outlet, a device being provided for modifying the maximum cross section of the path going from the upper part of the crushing elements to the output.

Embodiments of the invention will be described below, by way of example, with reference to the accompanying schematic drawings in which FIGS. 1 and 2 are vertical axial sectional views of alternative mills.

Each of the grinders shown in the drawings is essentially a so-called type E grinder. The grinder comprises a circle of grinding balls 1 held between an upper grinding ring 2 which is fixed and a lower grinding ring 3 which rotates. The material to be ground passes radially outward between the grinding rings. A nozzle circle k is provided for M to deliver air upwards opposite the outer periphery of the rings in order to entrain the ground material and to transport it upwards towards the outlet 5 of the casing 6 which contains the grinding surfaces.

An annular baffle 10 extends concentrically with the crown 2 and vertically upwards from the latter, the side walls 10a and 10b of this baffle converging upwards at equal angles relative to the vertical. The internal lateral walls of the envelope 6 are provided with a lining 1 ^, the lower part 1H-a of which is frustoconical. The part l * + a. slightly converges towards the wall 10b, but, in other embodiments, it can be parallel to the wall 10b. From a level below the upper ends of the baffle 10, the trim has an upper part 11¾ which is connected to the part 1½ and which diverges towards the outside.

A core 20 extends concentrically downward in the space provided inside the baffle 10, the outer surface of this core being frustoconical and parallel to the wall 10a and to the part 1 ^ -b. The maximum section of the flow path for the material which leaves the grinding zone and which flows towards the outlet 5 is determined by the axial position of the core 20 relative to the lining 1½. So that its position can be adjusted, the core is suspended by threaded rods 21 which cooperate with nuts bearing on the upper wall 6a of the casing 6, so that by adjusting the positions of the nuts on the rods 21, we can modify the height of the core 20.

The upper surface 20a of the core has a double slope, so that any material falling on this surface l descends and enters the flow of transport air or returns to the grinding zone.

The wall 10a of the baffle 10 is parallel to the external surface due. core 20 and the space which separates them forms a return passage through which the material which is not entrained towards the outlet can return to the grinding zone.

In operation, the material to be ground passes radially outward between the grinding rings 2 and 3 in order to be entrained by the air delivered by the nozzles A fraction of the material entrained upward by the air passes through the outlet 5 while another fraction falls back and passes between the walls 10a and the surface of the core 20 to return to the grinding zone. The fineness of the material passing through the outlet can be modified by modifying the maximum section at the upper end of the baffle 10.

As the cross-section increases, the speed decreases and it is possible to envisage variations in the fineness of the material which is entrained towards the outlet 5 ranging between in particular 99.9% less than 1.27 cm and 99.9% less than 1.59 mm.

In a variant of the embodiment described, means are provided for modifying the height of the liner 1 * + in order to vary the maximum section at the upper end of the baffle for the passage of the material "crushed from the crushing zone to the exit.

In the embodiment which is shown in FIG. 2, the baffle 10 has the shape of a regular cylinder.

The wall 106 of the envelope with which the baffle 110 cooperates to form the upward flow trumpet is also a cylinder parallel to the baffle. Only the upper part 120b of the outer surface of the core 120 is frustoconical and the measurement of the engagement of this core below j of the level of the upper end of the baffle determines the maximum flow path for the entrained material. The height of the core 120 can be adjusted by nuts screwed onto rods 21 while the other essential parts of the grinder, such as the grinding rings 2 and 3 and the grinding balls 1 are similar to those of the previous embodiment.

In the two embodiments, the baffle is mounted on the upper grinding ring 2 so as to move with this ring insofar as it wears out in service.

ΡΠ · O _ _ P7U-Q / LUX

Claims (8)

1. Crusher, characterized in that the material to "grind passes through a set of grinding elements" and the crushed material is discharged in a gas flow from the grinding elements to an outlet, a device being provided * for varying the maximum section of the path from the upper end of the grinding elements to the outlet. 2, - crusher according to claim 1, characterized in that a device is provided for defining a return path by which the material reaching the region of section * maximum and not driven downstream of this region can return to the elements grinders. 3 · - crusher according to claim 2, characterized in that the grinding elements are arranged in a horizontal circle, an annular baffle extends upwards from the circle, the path that the ground material follows from the grinding elements being defined by the outer surface of the baffle and by a surrounding annular wall, and the path by which the ground material can return. nir grinding elements comprising the internal surface of the baffle and a core which extends in this baffle and which, above the baffle, determines the region of maximum section. k -.- Mill according to either of Claims 3 and * +, characterized in that the height of the core with respect to the baffle is adjustable and the maximum section depends on the extent of the engagement of the core in chicanery. Crusher according to either of Claims 3 and * +, characterized in that the maximum section is determined by the outer surface of the core and by an annular surface surrounding the core and extending above the baffle, the surfaces can be moved axially relative to each other and being such that the maximum separation between them above the baffle is determined by their relative axial position. 6.- Crusher according to claim 5 \ characterized in that the annular surface and the outer surface are coaxial inverted frustoconical surfaces having equal or almost equal semi-vertical angles. 7 · - crusher according to either of claims 5 and 6, characterized in that the annular surface is formed by a lining mounted on the envelope of. grinder and being able to move in one direction or the other with respect to this envelope. 8.- Crusher according to any one of claims 3 to 8, characterized in that a device is provided for delivering air upwards opposite the elements j grinders in the path in which the ground material passes while leaving the grinding elements. 9 · - crusher according to any one of claims 3 to 8, characterized in that the baffle has two frustoconical surfaces converging upwards, and the surrounding annular wall as well as the surface of the core which cooperates with, the internal surface of the each chicane has the shape of a frustoconical surface having the same semi-vertical angle as that of the surface of the chicane with which they cooperate respectively. 10.- Grinder according to any one of the claims *. cations 3 to 5, characterized in that the baffle is formed by a cylindrical wall which is parallel to the surrounding annular wall and, above the baffle, the core has an outer frustoconical surface. 11.- Grinder in substance as described with reference to the accompanying drawings. r j P- ♦ v T