GB2278789A

GB2278789A - Pressure measuring; ball mill

Info

Publication number: GB2278789A
Application number: GB9410957A
Authority: GB
Inventors: Paul David Bates
Original assignee: Edwards and Jones Ltd
Current assignee: Edwards and Jones Ltd
Priority date: 1993-06-09
Filing date: 1994-06-01
Publication date: 1994-12-14
Anticipated expiration: 2014-06-01
Also published as: GB9311939D0; GB9410957D0; GB2278789B

Abstract

Apparatus for measuring the pressure in a closed vessel e.g. a ball mill 10, comprises connecting means connecting with interior of vessel in communication with a pressure measuring apparatus 22 which collecting means is selectively closable. As, shown a block 24 is removably mounted in the wall of the drum 12 of the mill 10. A bore 32 is provided through the block 24. A valve stem 46 extends through the bore 32 and is threadably mounted therein to permit a head 50 of the stem 46 to selectively open or close the bore 32 relative to the interior of the drum 12. The bore 32 connects to a pressdre gauge 56 and pressure relief valve 58 for relief of excess pressure. <IMAGE>

Description

Pressure Measuring Apparatus This invention concerns pressure measuring apparatus, and particularly but not exclusively apparatus for measuring the pressure within a closed vessel, and especially apparatus for measuring the pressure within a ball mill.

A ball mill generally comprises a closed cylindrical vessel which is rotated about its axis.

Locatable within the vessel is material to be ground and grinding media which may comprise pebbles or balls. The grinding media reduces the particle size of the material as the barrel is rotated. The interior of the barrel is usually lined, and linings of rubber, stainless steel or porcelain brick may be used.

Ball mills are often run for extended periods such as for example twenty four or thirty six hours. During this time very high pressures can build up in the vessel which can result in dangerous accidents. It is not desirable to release pressure in a ball mill during milling, unless of course very high pressures develop.

Up to now no satisfactory system has been provided for indicating or measuring the pressure within a ball mill during use.

A number of problems are encountered when trying to measure the pressure within a ball mill. These include the fact that the mill is rotated during use.

Furthermore, the conditions within the mill are very hostile, and thus if conventional pressure measuring apparatus was used this would probably be damaged if not destroyed as a result of being impacted by material being milled. Also, conventional apparatus is unlikely to operate satisfactorily in such hostile conditions.

According to the present invention there is provided apparatus for measuring the pressure within a closed vessel, the apparatus comprising means connecting with the interior of the vessel, means for selectively closing the connecting means, and a pressure measuring device in communication with the connecting means.

The apparatus is preferably removably mountable on the vessel.

The closing means is preferably movable towards the interior of the vessel when moving from a closed condition to an open condition whereby to urge material away from the connecting means.

The closing means may be mounted on a screw thread so as to be rotatable between open and closed conditions. The closing means may have a head engagable with a shoulder which faces towards the interior of the vessel, to close the connecting means, whereby the closing means is movable towards the interior of the vessel to open the connecting means.

The apparatus may include a valve connected so as to permit pressure within the vessel to be released.

The pressure measuring device may be removable from the connecting means, and a single pressure measuring device may be usable with a plurality of vessels.

The invention further provides apparatus for measuring the pressure within a ball mill, the apparatus being according to any of the proceeding eight paragraphs.

The invention yet further provides a ball mill fitted with such a pressure measuring apparatus.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a side view of a ball mill incorporating pressure measuring apparatus according to the present invention; and Fig. 2 is a diagrammatic cross-sectional view of the pressure measuring apparatus of Fig. 1.

Fig. 1 shows a ball mill 10 comprising a rotatable drum 12. Axles 14 extend from each end of the drum 12 and are mounted in bearings 16 on supports 18. A hydraulic torque motor 20 is provided on the end of a one of the axles 14. Mounted on and extending through the drum 12 is pressure measuring apparatus 22. The apparatus 22 is located substantially midway between the axles 14.

Considering the apparatus 22 in more detail. The apparatus 22 comprises a block 24 which sealingly fits in a hole 26 in the wall of the drum 12. The block 24 is removably mounted in the hole 26 and held therein by a pair of brackets 28 engagable with pivotal mounting screws 30 provided on the exterior of the drum 12.

A central bore 32 extends through the block 24. A first lowermost section 34 of the bore 32 is of greatest diameter but extends only a short way upwards into the block 24. The first section 34 connects with a second section 36 thereby providing a step 38 which faces into the interior of the drum 12. The second section 36 connects with a third section 40 of further reduced diameter which extends to the outside of the block 24.

The lowermost part of the third section 40 is defined by a threaded bush 42. The remainder of the third section 40 is smooth sided, and an 0-ring 44 is provided therearound adjacent the free end thereof.

A valve stem 46 extends through the bore 32. A nut 48 is provided on the upper end of the stem 46 remote from the interior of the drum 12, to permit rotation of the stem 46 by a,suitable tool. A head 50 of increased diameter is provided on the other end of the stem 46 and is engagable with the step 38 to close the bore 32. The remainder of the stem 46 is of a size to slidingly fit through the third section 40.

A pair of diametrically opposed passages 52,54 extend from the second section 36 adjacent the connection with the third section 40. A first of the passages 52 connects to a pressure gauge 56. The second passage 54 connects with a pressure relief valve 58 operable by a handle 60.

In use, the drum 12 is filled with material to be ground and grinding media, through the hole 26 if required. The apparatus 22 is then fitted into the hole 16 to act as a "running plug". Prior to fitting of the apparatus 22 the hole 16 is obviously kept uppermost to avoid spillage. The mill 10 is then run. Periodic checks can be made of the pressure within the drum 12 in the following manner. The mill 10 is stopped. The stem 46, which has previously been screwed tight against the step 38, is screwed towards the interior of the drum 12 thereby connecting the bore 32 and hence passage 52 and gauge 56 to the interior of the drum 12. The pressure can then be read and if excess pressure is detected this can be released by operation of the relief valve 58.

The gauge 56 can obviously be read during release of pressure to permit a required pressure to be retained.

Once milling is complete, pressure within the drum 12 is released using the valve 58 with the apparatus 22 on the uppermost part of the drum 12. The apparatus 22 is then removed from the drum 12 and a drainage plug (not shown) fitted. The drum is then rotated so that the drainage plug is lowermost whereby the material may be drained therethrough from the drum 12.

There is thus decribed pressure measuring apparatus which permits the pressure within a ball mill to be measured during the milling process without the loss of any substantial pressure from within the mill.

The arrangement of the stem and the fact that this moves into the drum to operate the apparatus means that material is urged away from the apparatus thereby ensuring accurate operation thereof without any clogging up of material occurring. The apparatus is of relatively simple construction and can thus be inexpensively and robustly manufactured. The construction of the valve ensures that the apparatus is protected during milling and any impacting of the apparatus occurs on the underside of the valve stem.

Various modifications may be made without departing from the scope of the invention. For example, any suitable pressure gauge may be used and the pressure gauge could be removable to permit use of the same gauge on a number of mills. Whilst the described apparatus is intended for use on ball mills, apparatus according to the invention could be used in many different situations and is particularly well suited to measuring pressures at selected instances in harsh working conditions.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims:-

1. Apparatus for measuring the pressure within a closed vessel, the apparatus comprising means connecting with the interior of the vessel, means for selectively closing the connecting means, and a pressure measuring device in communication with the connecting means.

2. Apparatus according to Claim 1, in which the apparatus is removably mountable on the vessel.

3. Apparatus according to Claims 1 or 2, in which the closing means is mounted on a screw thread so as to be rotatable between open and closed conditions.

4. Apparatus according to any of the preceding claims, in which the closing means is movable towards the interior of the vessel when moving from a closed condition to an open condition whereby to urge material away from the connecting means.

5. Apparatus according to Claim 4, in which the closing means has a head engagable with a shoulder which faces towards the interior of the vessel, to close the connecting means, whereby the closing means is movable towards the interior of the vessel to open the connecting means.

6. Apparatus according to any of the preceding claims, in which the apparatus includes a valve connected so as to permit pressure within the vessel to be released.

7. Apparatus according to any of the preceding claims, in which the pressure measuring device is removable from the connecting means.

8. Apparatus according to Claim 7, in which a single pressure measuring device is usable with a plurality of vessels.

9. Apparatus for measuring the pressure within a ball mill, the apparatus being according to any of Claims 1 to 8.

10. A ball mill fitted with pressure measuring apparatus according to any of Claims 1 to 8.

11. A ball mill substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

12. Pressure measuring apparatus substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

13. Any novel subject matter or combination including novel subject matter disclosed in the foregoing specification or claims and/or shown in the drawings, whether or not within the scope of or relating to the same invention as any of the preceding claims.