GB2113660A

GB2113660A - Spiral entry for raw coal bunkers

Info

Publication number: GB2113660A
Application number: GB08233326A
Authority: GB
Inventors: Hans-Dieter Gutsche; Kurt-Heinz Voss
Original assignee: Ruhrkohle AG; Bergwerksverband GmbH
Current assignee: Bergwerksverband GmbH; RAG AG
Priority date: 1981-12-19
Filing date: 1982-11-23
Publication date: 1983-08-10
Also published as: DE3232189A1

Abstract

The wear on the spiral entry of raw coal bunkers is effectively reduced in that beneath the discharge drum 2 and before the entry chute 3 a collecting table 1 having defining walls raised at the sides and on the rear is arranged in an approximately horizontal or slightly inclined position. This collecting table is formed so that according to inclination it can retain larger or smaller quantities of loose bulk material, but in any case can preserve a natural slope which ensures a regular introduction, at reduced speed, of the bulk material into the spiral chute. Such a collecting table is especially well adapted to regularise the charging of the spiral entry from several conveyor belts, while a load- dependent controlling of the inclination of the collecting table is possible by association of a belt balance 14 with the conveyor belt or belts. <IMAGE>

Description

SPECIFICATION Spiral entry for raw coal bunkers The invention relates to a spiral entry for spiral chutes, especially for raw coal bunkers in underground coal mining, which are charged by way of one or more conveyor belts, consisting of an entry chute arranged between the discharge drum of the conveyor belt and the bunker spiral.

Underground spiral chutes of raw coak bunkers, like the spiral chutes laid in blind shafts, are charged with high speed belts. Frequently several conveyor belts are allocated at the same time to one such spiral entry. The introduction of the flow of material takes place in a manner in which the raw coal is transferred from the discharge drum into the bunker spiral by way ofatangentially arranged inclined entry chute.

Especially for reasons of grain preservation it is here sought to keep the free height of fall of the discharge parabola and the angle between the tangent to the parabola of fall and the inclination of the entry chute as small as possible. The known constructions however do not constitute either a grain preserving or a low-wear construction. This is attributable to the fact especially that the raw coal flow from the discharge drum strikes at a high speed of fall at different angles upon the entry chute. As a result of the occurring rebound the flow of material is raised somewhat the point of impact and strikes afresh at a lower point upon the entry chute. The same process is repeated here, admittedly to a diminished extent. Thus the entire entry process can be represented in the form of a damped sine wave.

Apart from the grain comminution this form of entry would have no further disadvantages if erosions of cavity form were not to form in the chute surface iinings at the points of impact as a result of the impact wear. These erosions increase the lifting away of the raw coal flow, lead to a greater grain comminution and cause the progress of the wear in the same form downwards. This negative effect, increasing the comminution and wear, is further increased if two or more flows of raw coal are combined into one entry construction.

It has also already been attempted to cause the coal delivered by the conveyor belts to strike upon a cushion of the same material. Admittedly this solution has the disadvantage that, especially in the case of a high proportion of damp fine coal or sludge, a vertical or even overhanging slope builds up leading to blockages in the entry construction.

The invention is, therefore, based upon the problem of producing a grain-preserving spiral entry which is easily adaptable to the existing conditions of conveying.

The problem is solved according to the invention in that beneath the discharge drum and before the entry chute a collector table, having defining walls drawn up at the sides and on the rear, is arranged in an approximately horizontal position.

With such a construction of the spiral entry it is possible to avoid the described disadvantages in an advantageous manner and surprisingly simply. The collector table is so arranged and has such a great extent in the direction of the entry construction that the conveyed material firstly collects on it and forms a natural slope, on which then the further charged coal can slide down and into the entry chute and then be introduced into the bunker spiral. The dimensions of the collector table ensure that the natural slope acquires precisely such form and dimensions that the subsequently arriving raw coal is guided precisely into the entry chute.Thus even in the case of unfavourable coal it is not possible for blockages to occur within the entry chute or the bunker spiral. In order to avoid an unfavourable or even over hanging slope even in the case of unfavourable coals or unfavourable conveyed material, according to the invention it is provided that the inclination of the collecting table is adjusted. This is achieved accord ing to the invention in that the rear legs, in the conveying direction, of the collecting table are formed as hydraulic or pneumatically operable cylinders, while the collecting table is mounted pivotably on the forward legs in the conveying direction.

According to a further development of the invention it is provided that vibrator or thrust drive systems are associated with the resiliently mounted collecting table. With the aid of such accessories it is possible with the collecting table according to the invention to convey even the most difficult material in a protective manner into the entry chute.

A directed build-up of the natural slope is achieved and guaranteed according to the invention in that the height of the defining walls, especially the lateral defining walls, is one-quarter to one-third of the width of the collecting table. At the same time according to a further development it is provided that the collecting table extends beyond the discharge drum to beneath the conveyor belt, so that an optimum natural slope forms, since the conveyed material can also slip down to the rear.

An automatic adaptation of the inclination of the collecting table to the existing conditions, that is to say the delivered quantity and to the delivered material, is possible in accordance with the invention in that the inclination of the collecting table is controllable according to load, by means of the conveyor belt. In the case of light belt loading the collecting table of hydraulically adjustable inclination is set more flatly, so that the loose bulk material is stored more before it is transferred into the spiral chute. In the case of heavy belt loading on the other hand a greater inclination of the collecting table is caused, so that hardly any buffer effect of the loose bulk material takes place.As a result of this automated control system of the spiral charging, which is advantageously achieved in that a belt balance arranged shortly before the discharge drum is associated with the conveyor belt and is connected through a control lead with the rear legs or corresponding cylinders, a flow of loose bulk material of regularised intensity should always be fed to the bunker spiral chute.

The technical progress is to be seen especially in that with the construction in accordance with the invention a spiral entry is produced with which, irrespective of the number of feeding conveyor belts, a regular introduction of the conveyed material into the spiral is given, causing approximately no wear.

Stoppages and other troubles can be excluded effectively and with simple measures, in that the inclination of the collecting table is simply adapted to the existing conditions. Due to the fact that a natural slope is built up on the collecting table, here again no wear occurs. With this kind of charging at the same time a maximum grain preservation with minimum possible wear of the bunker spiral lining is achieved. As a result of the heavy flow of loose bulk material the coarse waste pieces are better embedded and then no longer tend to burst. The slow, regularised flow of loose bulk material has only a minimal parabola of fall at the transfer to the entry construction, so that hardly any rebounding of the bulk material occurs which in the case of direct belt charging leads to the feared undulatory wear of the spiral lining.

Further details and advantages of the object of the invention appear from the following description Figure 1 shows a spiral entry with interposed collecting table in lateral elevation, Figure 2 shows the spiral entry according to Figure 1 in plan view, Figure 3 shows a collecting table of variable inclination, and Figure 4 shows a collecting table with vibrator or thrust drive.

In the arrangement as shown in Figure 1 the collecting table 1 is arranged in an approximately horizontal position beneath the discharge drum 2 of the feeding conveyor belt 6 and before the entry chute 3. By reason of the great extent of the collecting table 1 in the direction of the entire entry construction, the charged conveyed material 4 collects on the collecting table and forms a natural slope. The conveyed material 4 can thus slide over the natural slope into the entry chute 3 and thence into the spiral chute 5, as is also made clear from Figure 2.

On charging with the conveyed material, especially on charging with damp raw coal, coal fines or sludge, in which a steeper angle of slope can establish itself, the collecting table 1 can be varied in inclination, as represented in Figure 3, in that the rear legs 10 in the conveyed direction are extended.

For this purpose the legs 10 allocated to the rear 11 are formed as hydraulically or pneumatically operable cylinders. At the end pointing to the entry chute 3 the collecting chamber 1 is provided with a hearing 7 permitting an appropriate pivoting movement.

According to Figure 4 the collecting table 1 can also be formed so that it is arranged with a slight inclination in the direction of the entry chute 3 and has a vibrator or thrust drive 12. The raw coal with a high content of damp fines or sludge can thus likewise be fed easily to the entry chute, without the possibility of occurrence of wear on the entry chute in this case. Any occurring wear is concentrated on the easily replaceable or repairable collecting table 1.

The defining walls 8,9 are raised so that in each case an optimum natural slope of the conveyed material 4 establishes itself. They preferably have a height corresponding to one-quarter to one-third of the width of the collecting table, but other heights of the defining walls 8, 9 can also be selected according to the number of the feeding conveyor belts 6.

The essential advantages of the spiral entry are to be seen in the low speed of entry of the flow of raw coal into the spiral chute, which is achieved by the fact that the speed of the conveyed material 4 discharged from the discharge drum 2 is braked greatly on the natural slope. Furthermore, the low height of fall from the natural slope on to the entry chute 3 is advantageous; because thus only a minimum rebounding of the conveyed material can occur, so that the wear on the lining of the chute surfaces is kept within limits. By reason of the good adaptability to the different grain compositions and the moisture of the entering flow of raw coal, troubles in conveying are reliably avoidable.

The rear legs 10 or the cylinders arranged there are connected in Figure 3 through a control lead 15 with a belt balance 14 arranged directly before the discharge drum. By means of the belt balance the collecting table can advantageously be controlled in load dependence, in that in the case of light belt loading the inclination of the hydraulically adjustable collecting table is set more flat and in the case of heavy loading it is made greater. In the case of flat inclination the bulk material is stored more before it is transferred into the spiral chute, while the case of heavy belt loading and thus greater inclination of the collecting table it is transferred into the spiral chute with only slight buffer effect.

Claims

1. Spiral entry for spiral chutes, especially for raw coal bunkers in underground coal mining, which are charged by means of one or more conveyor belts, consisting of an entry chute arranged between the discharge drum of the conveyor belt and the bunker spiral, wherein beneath the discharge drum (2) and before the entry chute (3lea collecting table (1) having defining walls (8, 9) raised at the sides and on the rear (11) is arranged in approximately horizontal position.

2. Spiral entry according to Claim 1, wherein the collecting table (1) is adjustable in inclination.

3. Spiral entry according to Claim 1, wherein the vibrator drive systems (12) are associated with the resiliently mounted collecting table (1).

4. Spiral entry according to Claims 1 and 2, wherein the rear legs (10), in the conveying direction, of the collecting table (1) are formed as hydraulically or pneumatically actuatable cylinders.

5. Spiral entry according to Claim 1, where the height of the defining walls (8, 9), especially of the lateral defining walls (8), amounts to one-quarter to one-third of the width of the collecting table (1).

6. Spiral entry according to Claim 1, wherein the collecting table (1) extends beyond the discharge drum (2) to beneath the conveyor belt (6).

7. Spiral entry according to Claim 1 and Claim 4, wherein the inclination ofthe collecting table (1) is controllable in dependence upon load by means of the conveyor belt (6).

8. Spiral entry according to Claim 7, wherein with the conveyor belt (6) there is associated a belt balance (14) arranged shortly before the discharge drum (2), which is connected through a control lead (15) with the rear legs (10) or corresponding cylinders.

9. Spiral entry for spiral chutes, especially for raw coal bunkers in underground coal mining, substantially as described herein with reference to the accompanying drawings.