GB2153702A - Mineral breaker - Google Patents

Abstract

A mineral breaker 10 has a breaker drum 14 rotatably mounted in a housing 12, the housing having an inlet for mineral to be broken and an outlet for broken mineral, the inlet and outlet being offset from one another axially of the drum. The drum has a first formation 20 for breaking and moving the broken mineral axially of the drum toward the outlet and to a second formation 22 which acts upon the broken mineral to break it down further. <IMAGE>

Description

SPECIFICATION Mineral breaker The present invention relates to a mineral breaker.

In particular the present invention relates to a mineral breaker which can be used in confined spaces such as in mines. Advantageously a mineral breaker made in accordance with the present invention may be located adjacent to a face working in a mine and used to break down mineral and supply it to a pipeline for discharge for back packing purposes.

According to one aspect of the present invention there is provided a mineral breaker having a breaker drum rotatably mounted in a housing, the housing having an inlet for mineral to be broken and an outlet for broken mineral, the inlet and outlet being offset from one another axially of the drum, the drum having a first formation for breaking and moving the broken mineral axially of the drum toward the outlet and to a second formation which acts upon the broken mineral to break it down further.

Reference is now made to the accompanying drawings, in which: Figure 1 is a side view of a first embodiment according to the present invention; Figure 2 is a plan view of the embodiment shown in Figure 1 with upper casing parts removed to show the breaker drum; Figure 3 is a sectional view taken along line Ill-Ill in Figure 1; Figure 4 is a sectional view taken along line IV-IV in Figure 1; Figure 5 is a plan view of a second embodiment of the present invention with its upper casing parts removed to show the breaker drum; and Figure 6 is a sectional view taken along line VI-VI in Figure 5.

The mineral breaker 10 shown in the drawings includes a housing 12 in which is rotatably housed a breaker drum 14. The lower portion of the housing defines a trough 15 of circular cross-section which is preferably constant along its length and the breaker drum 14 is positioned within the trough so that breaker teeth or picks projecting from the drum co-operate with the sides of the trough to break down material.

The drum 14 includes a small diameter portion 16 and a large diameter portion 18 which are separated from one another by a frusto-conical portion 19. The small diameter portion 16 is provided with a first breaking formation 20 which serves to cooperate with the sides of the trough to perform a coarse or primary breaking action on the mineral and also functions to move the broken mineral axially of the drum toward the frusto-conical portion 19.

The first formation 20 is preferably defined by breaker teeth in the form of picks arranged to define discrete helical formations for moving the mineral axially of the drum, or the combination of breaker teeth or picks and one or more helical ribs may be provided, the teeth or picks serving to break the mineral and the helical rib or ribs serving to move the broken mineral axially of the drum.

In the illustrated embodiment, picks 25 are provided which are arranged in double rows to define discrete helical formation 26. The rib 27 serves as a support for the picks and also a means of positioning the picks during assembly. The maximum size of mineral produced by the first formation is determined by the clearance spacing between the tips of the picks from the sides of the trough, the spacing between each adjacent pick along the helix and the spacing between the convolutes of the helix.

The convolutes of the helical formation extend from the small diameter portion 16 and onto the frusto-conical portion 19 to define a second breaking formation 22. The helical formation on the frusto-conical portion is preferably defined by a single row of picks. Accordingly the picks mounted on the frusto-conical portion 19 become progressively closer to the sides of the trough the further they are located from the small diameter portion.

The maximum and minimum spacing of the picks from the trough is clearly visable in Figures 3 and 4 respectively. Accordingly mineral being moved axially along the frusto-conical portion 19 is exposed to a progressive breaking action which further reduces the maximum lump size of the mineral. In order to provide regular shaping of the lumps of mineral being broken the spacing between the convolutes of the helix on the frustoconical portion is preferably progressively reduced with increase in diameter.

The axial extent of the frusto-conical portion and the difference in diameter between the small and large diameter portions 16 and 18 respectively define the included angle of the frusto-conical portion and also the rate at which picks become progressively closer to the sides of the trough per unit axial length of the drum. Preferably the included angle of the frusto-conical portion 19 is in the range of 5" to 90O, more preferably between 10 to 30".

The large diameter portion 18 is located within an enclosed chamber 30 which has an outlet 32 through which broken mineral is discharged.

In the first embodiment, the outlet 32 is intended to be connected to a duct along which pressurised air flows for transporting the broken mineral away for back packing. It is envisaged that some arrangement may be provided for preventing leakage of pressurised air through the enclosed chamber, for instance a paddle arrangement may be provided on the large diameter portion. In order to give outlet 32 sufficient clearance from the ground the housing is conveniently mounted on a support 40 which also conveniently provides a framework for supporting the drive motor 41. The upper portion of the enclosed chamber is conveniently defined by a hinged cover plate 42 which may be raised to give access to the interior of chamber 30.

The upper portion 45 of the housing in the vicinity of the first breaking formation 20 has raised sides 46 and an upper opening 47 through which mineral to be broken is deposited onto the breaker drum. Preferably one of the sides 46 is defined by a hinged plate 48 which is arranged to pivot downwardly toward the breaker drum in order to exert pressure on large pieces of mineral to assist in the breaking action. The plate 48 is driven by a hydraulic ram 50 which acts upon arm 51 depending from plate 48.

The outlet 32 is conveniently provided with a plate valve 55 for regulating the rate of discharge from the breaker 10. Operation of the valve 55 may be performed during operation of the mineral breaker since the helical formation (whether defined by teeth, picks andlor ribs) is spaced sufficiently far from the sides of the surrounding walls of the housing to enable the mineral to "boil" i.e.

the drum is designed to urge the material to move along the trough without compressing it so that if the outlet is closed the broken mineral is merely agitated by the drum. Accordingly the flow of mineral through the breaker may be assisted by tilting the drum and housing so that the flow is gravity assisted.

It is envisaged that the present mineral breaker may be used to size mineral down to a desired maximum sizing and that to achieve the desired sizing the length of the breaker drum may be increased to accommodate more than one frustoconical portion having a breaking formation so that as mineral is moved axially along the drum it is progressively broken to a smaller maximum sizing.

A second embodiment is illutrated in Figures 5 and 6. The second embodiment is basically of the same construction as the first embodiment except that a different arrangement is provided for discharge of the broken mineral.

In the second embodiment the outlet opening 50 communicates with a conduit 52 which extends transversely across the trough 15. The position of the conduit 52 and opening 50 is such that some of the picks 25 of the second formation preferably sweep into and out of the conduit 52 as the drum rotates in a clockwise direction as illustrated in Figure 6.

The conduit 52 has an inlet 55 which is connected to a source of pressurised air. A nozzle 56 is positioned adjacent to the inlet and upstream of the opening 50. The size and position of the nozzle 56 and rate of flow of air therethrough is chosen so that the nozzle is able to direct the flow of air across the opening 50 as it flows through the conduit 52 to enter the outlet portion 58 of the conduit 52 whilst minimising escape of air through opening 50 and into the housing 12.

It has been found that it is possible with the second embodiment to transport broken mineral away from the breaker and along discharge pipe 60 for relatively long distances. This is particularly advantageous for back fill purposes in a mine and is thought to be attributed to the fact that mineral being deposited into the conduit 52 is urged in the direction of flow of air through conduit 52 by the rotation of the drum so that the air flow needs only to accelerate moving mineral up to transport speed whereas in previous arrangements the air flow needs to accelerate the mineral from a standstill.

Additionally the minieral falling through opening 50 is exposed to an accelerated air flow created by the nozzle which assists in accelerating the mineral up to transport speed.

A further advantage possessed by the second embodiment is that the height necessary to accommodate the breaker is substantially reduced as may be seen by comparing Figures 4 and 6 wherein the supporting frame 40 for the second embodiment need only be of sufficient height for providing ground clearance for conduit 52. This is particularly advantageous in the confines of a mine.

Claims (8)

1. A mineral breaker having a breaker drum rotatably mounted in a housing, the housing having an inlet for mineral to be broken and an outlet for broken mineral, the inlet and outlet being offset from one another axially of the drum, the drum having a first formation for breaking and moving the broken mineral axially of the drum toward the outlet and to a second formation which acts upon the broken mineral to break it down further.

2. A mineral breaker according to Claim 1 wherein the breaker drum has a small diameter portion and a large diameter portion, the small and large diameter portions being separated by a frusto-conical portion, said first formation being located on the small diameter portion and said second formation being located on the frusto-conical portion.

3. A mineral breaker according to Claim 2 wherein said second formation extends on to the large diameter portion.

4. A mineral breaker according to Claim 2 or 3 wherein the first and second formations are defined by a series of breaker teeth arranged in discrete helical paths.

5. A mineral breaker according to Claim 2, 3 or 4 wherein the drum is positioned in a trough of circular section and an outlet opening for the broken mineral is formed in the trough in the vicinity of the large diameter portion.

6. A mineral breaker according to Claim 5 wherein the outlet opening communicates with a conduit extending transversely of the trough, and along which air is directed for transporting the broken mineral away.

7. A mineral breaker according to Claim 5 wherein the outlet opening and conduit are positioned so that breaker teeth of the second formation sweep into and out of the conduit during rotation of the drum.

8. A mineral breaker substantially as described with reference to and as illustrated in any of Figures 1 to 4 or 5 and 6 of the accompanying drawings.