GB2152840A - Mineral breaker - Google Patents

Abstract

The breaker comprises a rotatably driven breaker-drum (19) having teeth (21) secured to its periphery at axially and circumferentially spaced positions. At one side of the drum is a spring-loaded plvotably-mounted breaker- plate (27) with tines 33 spaced along its length and so disposed that the teeth can pass therebetween. The tines so extend under the drum that whereas broken mineral falls between the tines and thence out of the breaker substantially at the side of the drum at which the plate (27) is disposed, non-breakable material is diverted by the fines to a discharge position spaced from that of the broken mineral. <IMAGE>

Description

SPECIFICATION Mineral breaker This invention relates to mineral breakers and in particular to mineral breakers capable of sizing mineral to small sized material.

There are numerous types of such mineral breakers presently available. In general, a rotatable breaker drum with circumferential breaker teeth is disposed adjacent a breaker plate so that, in use, as mineral is fed to the breaker drum, it becomes trapped between the drum and the breaker plate where the breaker teeth bite into it to break it down into smaller pieces. The spacing of the drum from the breaker plate and the circumferential spacing of the breaker teeth from one another are chosen to break the mineral to the desired size.

Mixed with the mineral to be broken may be other material which will not break. If such material passes between the drum and the breaker plate, it could jam the mineral breaker, if both the drum and the breaker plate are fixed. To overcome this problem the breaker plate has been made movable so that if non-breakable material enters the breaker it can force the breaker plate away from the drum in order to pass through. The breaker plate is spring loaded to return to its normal position thereafter.

However with such an arrangement the nonbreakable material passes out of the mineral breaker with the broken, sized mineral. Thus a further operation will be required to separate out the nonbreakable material.

Accordingly, it is an object of the invention to provide a mineral breaker which, in use, can separate out at least some of any non-breakabie material in the mineral fed to the breaker.

According to the invention there is provided a mineral breaker comprising an opening through which mineral is fed to the breaker, in use, a rotatable breaker drum located below the opening and having breaker teeth thereon, a wall adjacent one side of the drum having at its lower end a plurality of spaced tines, the arrangement being such that, in use, the breaker teeth co-operate with said wall to break the mineral, which passes between the tines, whereas non-breakable material can be carried away by the tines to leave the breaker at a position different from that at which the broken mineral leaves.

Desirably the breaker teeth pass between the tines at a position below a horizontal centre line through the breaker drum, an arrangement which effectively reduces any recirculation of mineral to be sized by the rotating breaker drum. It also gives an improvement in the accuracy of sizing, coupled with an improved flow of mineral being sized through the machine.

Preferably the wall is in the form of a pivotable plate which can move away from the breaker drum against a biasing force when subjected to an excessive loading.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa part-sectional plan view of a mineral breaker constructed according to the invention, with only two breaker teeth being shown on the breaker drum, Figure 2 is a transverse sectional view through the mineral breaker of Figure 1,with a set of breaker teeth shown on the breaker drum, Figure 3 is apart-sectional plan view, similar to Figure 1, of an alternative embodiment of the invention.

The mineral breaker shown in Figures 1 and 2 has a rectangular casing comprising longitudinal sides 10,11 and transverse ends 12,13. The sides 10,11 have flat inner surfaces, but the side 10 has a pair of openings 14 spaced longitudinally apart and disposed just below its horizontal centre line. The ends 12, 13 also provide generally flat inner surfaces, but each end has a circular hole 15 through an annular outward extension portion 16 at an upper corner thereof adjacent the side 10. In addition each end has a larger diameter circular hole 17 disposed therein at a position level with said horizontal centre line of the side 10 but nearer the side 11 than said side 10, as best shown in Figure 2.

The sides and ends thus define a rectangular opening at the top of the breaker leading to a rectangular breaker chamber below it.

The holes 17 receive the respective ends of a shaft 18 of a breaker drum 19 rotatably mounted in said chamber. The circular peripheral surface of the drum has a plurality of pairs of axially spaced annular plates 20 welded or otherwise secured thereto. Between the plates of each pair are secured a plurality of breaker teeth 21, in this example eight, each of the breaker teeth being tangential to the drum surface, as shown in Figure 2. The number and disposition of the teeth can, however, be varied if required. For example, the teeth need not be equispaced around the drum surface. Each tooth has a cylindrical portion 22 received in a pocket 23 secured to the drum surface, with a frusto-conical portion 24 between the portion 22 and a conically pointed end 25. The teeth are so sized as to allow a slight clearance from the side 11.The drum shaft 18 can be supported and driven in any convenient manner.

A circular shaft 26 is received at its respective ends in the holes 15 in the portions 16 of the ends 12 and 13, so that it extends across the breaker chamber parallel to the drum 19. The shaft 26 carries a pivotable breaker plate 27, with bearing sleeves 28 between the shaft and the plate, the plate 27 having a hollow cylindrical end portion 29 fitting over the shaft 26 between the inner surfaces of the ends 12 and 13 respectively.

The breaker plate 27 has a wall portion 30 below said portion 29, the wall portion extending substantially the whole length of the portion 29 and providing an arcuate surface 31 facing the drum 19.

In its normally biased position, (to be described), which is that shown in Figure 2, the arcuate surface 31 extends into a series of spaced short, vertical, flat surfaces 32, the junction between the surface 31 and the surfaces 32 occuring at a position just below the horizontal centre line of the side 10. The surfaces 32 are disposed between pairs of tines 33 which continue the arcuate curve of the surface 31 and extend under the drum 19 and terminate short of the inner surface of the side 11, as shown in Figure 2.

The undersurface of the tines is also arcuate and the depth of each of the tines decreases from its junction with the surface 31 where it is equal to the depth of the surface 32, to a small curved end. At each end of the plate 27 a flange 33a perpendicular to the length of the plate continues the curve of the undersurface of the tines.

The relative disposition of the drum 19 to the breaker plate 27 is such that the teeth 21 are aligned with the vertical surfaces 32, so that the tines are aligned with the spaces on the drum surfaces between the pairs of plates 20, as shown in Figure 1.

There is a clearance between the pointed ends 25 of the teeth and the surfaces 31 and 32 to allow material to pass, as will be described.

In Figure 1 the tines are shown as being shorter than those of Figure 2. However the important feature of the length of the tines is that, as will be described, they are sufficiently long to carry away non-breakable material from the spaces between the tines through which the broken and small size mineral falls.

In each of the openings 14 in the side 10 is disposed a cylinder 34 which protrudes out of the side 10 and has its outer end closed. In the cylinder is secured a cylindrical rod 35 extending from the closed end to a position substantially level with the open end of the cylinder which is itself substantially level with the inner surface of the side 10. Slidably fitted on the rod 35 is a member 36, which projects from the cylinder 34 onto the breaker chamber and has a rounded end engaging against the rear surface of one of the vertical surfaces 32. Between the closed end of the cylinder 34 and a rear shoulder 37 of the member 36 is a compression spring 38.

Thus the spring biases the member 36 against the breaker plate 27 to hold it normally in the position shown in Figure 2. In this position mineral fed through the top of the breaker into the breaker chamber, for example from a conveyor, falls onto the plate surface 31 and drum surface and is broken by the teeth against the surfaces 32 as it falls through the chamber. The broken mineral and also any mineral already of a sufficiently small size fall vertically out of the bottom of the breaker to be collected, for example, by another conveyor.

Should any non-breakable material, such as tramp iron, be contained in the mineral fed to the breaker, this will normally be unable to pass between the teeth 21 and a corresponding surface 32 and will thus exert an excessive loading on the plate 27. This will cause the plate 27 to move pivotally away from the breaker drum against the members 36 and the biasing force of the springs 38 in the two cylinders 34 respectively, to the position shown in dashed lines at39 in Figure 2. The member 36 thus slides rearwardly in the cylinder 34 on its rod 35 to compress the spring 38. Once the non breakable material has cleared the drum and tines, the spring restores the plate 27, via the member 36, to its normal position.

The non-breakable material is carried on the tines by gravity to the respective ends thereof, where it falls therefrom into a discharge position indicated in phantom at 40 in Figure 2. This discharge thus takes place at a position spaced away from the discharge position of the mineral sized by the mineral breaker, and thus the two types of material are separated during the sizing process.

As is apparent from Figure 2, the teeth intersect with the breaker plate at a position just below the plane including the horizontal diameter of the drum shaft. However this position of intersection can be varied, for example, so that intersection takes place nearer or at the vertical plane through the drum shaft axis.

Figure 3 shows an alternative form of mineral breaker constructed in accordance with the invention, in which the breaker chamber contains two spaced breaker drums 41,42 arranged in parallel, with each drum being of substantially the same form as the drum 19 in the first embodiment.

In addition two pivotable breaker plates 43,44 in the same form as the plate 27, are associated with the drums 41,42 on shafts 45,46 respectively. The only significant difference from the Figures 1 and 2 embodiment is that the shafts 45,46 are disposed adjacent each other and midway between the longitudinal sides of the chamber. Accordingly the biasing force to return a breaker plate to the position shown must accordingly be adapted for th is different arrangement of breaker plate shafts. One possible arrangement is the use of a coiled torsion spring on the shaft.

As with the first embodiment, mineral to be broken is fed through the top opening of the breaker to each breaker plate and associated breaker drum.

At the bottom of the breaker, sized mineral is discharged vertically through, whilst any nonbreakable material is carried away by the tines to a discharge position spaced from that for the sized mineral.

The two drum shafts can be driven by either separately or by a common drive, and rotate in opposite directions.

Claims (11)

1. A mineral breaker comprising an opening through which mineral isfed to the breaker, in use, a rotatable breaker drum located below the opening and having breaker teeth thereon, a wall adjacent one side of the drum having at its lower end a plurality of spaced tines, the arrangement being such that, in use, the breakerteeth co-operate with said wall to break the mineral, which passes between the tines, whereas non-breakable material can be carried away by the tines to leave the breaker at a position different from that at which the broken mineral leaves.

2. A mineral breaker as claimed in claim 1 in which at each of a number of axially spaced positions along its length the breaker drum has a plurality of breaker teeth around its periphery, each of said axial positions being aligned with the space between a pair of said tines, so that, in use, the teeth pass between said pair of tines.

3. A mineral breaker as claimed in claim 1 or claim 2, in which the wall has a concave curved surface facing the breaker drum, with the spaced tines being defined at its lower end between respective recesses formed in said lower end of the wall.

4. A mineral breaker as claimed in any one of the preceding claims, in which the wall is mounted on a privot parallel to the axis of the breaker drum to enable it to pivot from a rest position in a direction away from the breaker drum.

5. A mineral breaker as claimed in claim 4, in which the wall is biased to its rest position and thus moves away therefrom in said direction away from the breaker drum against said bias.

6. A mineral breaker as claimed in any one of claims 2 to 5, in which the teeth pass between the tines, in use, at a position below a horizontal diametral plane through the breaker drum.

7. A mineral breaker as claimed in any one of the preceding claims, in which the tines formed at the lower end of said wall extend at least partly below the breaker drum, whilst the junction between said tines and the remainder of the wall is at said one side of the breaker drum, so that, in use, nonbreakable material is carried by said tines to a discharge position spaced from where broken material falls from said wall and between said tines.

8. A mineral breaker as claimed in claim 7, in which the tines extend fully under said breaker drum and terminate at the side thereof opposite from that at which said wall is disposed.

9. A mineral breaker as claimed in claim 7 or claim 8, in which at the junction of the tines with the remainder of the wall, a flange is provided between each pair of tines to define a rear surface for the space between each pair of tines and through which the broken material can fall, in use.

10. A mineral breaker as claimed in any one of the preceding claims, in which two of said breaker drums are provided, each having said wall adjacent one of its sides.

11. A mineral breaker substantially as hereinbefore described, with reference to, and as shown in Figures 1 and 2 or Figure 3 of the accompanying drawings.