GB2155977A

GB2155977A - Lining underground workings

Info

Publication number: GB2155977A
Application number: GB08505725A
Authority: GB
Inventors: Granville Fletcher Williams
Original assignee: Carrs Paper Ltd
Current assignee: Carrs Paper Ltd
Priority date: 1984-03-06
Filing date: 1985-03-06
Publication date: 1985-10-02
Also published as: GB8505725D0; GB8405841D0

Abstract

A material for lining underground workings comprises a pre-formed laminate of paper and suitable reinforcement which can be wound into a roll of compact dimension and unwound from said roll carried for example by self-advancing milling machinery. The material can be joined by links which enter holes formed adjacent to the edges of the material or by means of hooks which penetrate the material.

Description

SPECIFICATION Flexible laminated material and method of use This invention relates to flexible laminated materials of the kind which can be supplied in the form of rolls and to a method of using such material.

For many years, in current mining operations, particularly at an advancing face of a coal seam, it has been the practice as the face advances to line the roof of the working seam using materials unwound manually, or preferably unwound from rolls carried bythe advancing cutting machinery.

The lining is intended to serve two rather different functions: firstly to assist in the control of respirable dust and secondly, it is intended to withstand pieces of rock, varying in size, from falling into the work space.

Previously, because of the two different functions, two separate rolls of material have been employed. Dust exclusion has been achieved by means of paper or paper laminates which are readily available in appropriate dimensions but with a strength sufficient only for this purpose, i.e. such that the material can be handled and placed in contact with the exposed working. For supporting larger pieces of rock and loose material it has been necessary to use in conjunction with the paper a separate roll of wire mesh which affords the requisite strength to support the relatively heavy loads likely to be encountered. Whilst such mesh is readily available also, it cannot normally be obtained in lengths which are as great as that of the paper, resulting in more frequent stoppages in production for the replacement of the wire mesh reels than that of the paper reels.

Moreover, even if it were possible to obtain suppliers of wire mesh in longer lengths, corresponding to the length of the paper available, it would not in most cases be practicable to use it. The reason for this is that because of the nature of the mesh it can only be rolled loosely, otherwise adjacent layers tend to become tangled with one another so that the roll will not unwind easily. Accordingly the diameter of wire mesh reels of say 200m in length, would be far greater than that of a roll of paper of the same length, and furthermore could not be accommodated in the restricted space available on the cutting machinery at a coal face.

Additionally, for adequate security, adjacent lengths of such wire mesh require to be joined together at their edges. Currently, this is done by linking the two edges with a pig-tail type wire. This is a difficult operation, especially in the conditions which prevail at the working face.

Whilst these difficulties have been recognised for many years, and various alternatives have been proposed, none of the alternatives have proved to be acceptable.

This invention, however, provides a material and method of use which solves the problems experienced by the existing methods.

Broadly, the invention resides in the use of a single reel of lamination instead of two reels of paper and mesh respectively as previously used and an easier method of joining edges together.

Thus, the invention comprises a method of lining underground workings wherein an exposed surface of such working is covered by lengths of a single preformed flexible and reinforced laminated material which is unwound from rolls of such material by apparatus advancing along such working.

According to the invention, we also provide a flexible laminated material comprising at least one ply of paper which has been treated to render it substantially non-inflammable, and at least one layer of a reinforcement which has also been treated to render it substantially non-inflammable, bonded together by means of an adhesive substance which is also non-inflammable, the material as a whole being such as not to emit significant quantities of noxious substances if exposed to fire, the material having a bursting strength sufficient to enable it to support loose pieces of material without further reinforcement.

The paper previously used for dust exclusion are not available in a fire proof grade of sufficient strength, but the material in accordance with the invention can be made with a bursting strength at least four times greater than such known materials.

Preferably a non-water soluble fire retardent additive is used to render the paper noninflammable, and it may also be treated in known manner to increase the wet strength.

Preferably, the reinforcement is sandwiched between two plies of paper. The paper ply or plies add the necessary rigidity to the reinforcing ply which would be difficult to handle on its own.

Such material is effectively dust retarding and -assists in the control of respirable dust. It can readily be made of sufficient strength to withstand the fall of pieces of rock and to support same. It can e made in any required length and can be rolled tightly without difficulty so as to form a compact roll of relatively small diameter.

Whilst the reinforcement material is conveniently made from a natural vegetable fibre, such as jute, other woven or non-woven material could be used, including mineral fibre, artificial fibre, or plastic sheeting for example, subject to their suitability with regard to inflammability and the emission of noxious substances.

The reinforcement may for example be flame-proofed jute hession, and the paper may be any suitable grade of flame-proofed paper, typically having a weight of about 70 grams to 80 grams per square metre. The preferred adhesive is a hot melt adhesive, but other laminants which are for instance water based or formed by an extrusion process could be used if they possess the required flame retardency.

Tests have established that such material can be made with a tear strength in excess of about 400 Newtons/50mm (as determined according to British Standards Handbook II, 1964, 4/118) with typical values in the range 500 to 800 and that such material is wholly suitable for the present use. In particular, this laminate has the required strength and dust retaining properties; it is non-inflammable and does not emit significant quantities of noxious substances when exposed to fire, and is therefore suitable for use in underground workings.

The material can be paid out from rolls carried, for example, by self-advancing mining machinery. Because the hessian or other reinforcement extends substantially uniformly across the entire area of the material, adjacent lengths can be joined simply by threading wire or yarn through holes formed along the edges of the material or by means of devices such as hooks or snap fasteners. Hooks may penetrate the material at any pont without disrupting it, but preferably the material is formed with a row of spaced holes adjacent to each edge to receive wire links or the like to join adjacent lengths together. Typically, holes of about 6mm diameter would be punched at intervals of between about 50mm and 75mm, at approximately 50mm from each edge of the reel.Such links could be attached manually, but alternatively they may be provided at the required spacing on a backing strip so as to be applicable automatically by means of a suitable guide or roller mechanism.

The invention also resides in the use of such a flexible laminated material as defined above for the lining of underground mine workings by paying out lengths of such material from rolls carried by self-advancing mining machinery and joining adjacent lengths at their edges by means of transversely arranged links.

The preferred material in accordance with the invention, comprising a layer of jute hessian sandwiched between two layers of paper, can be made on conventional machinery up to a maximum width limited only by the width of paper making machinery available. A length of 1 00m can be formed into a roll having a diameter of about 40cm, and a 200m length can be formed into a roll having a diameter of about 52cm. These dimensions are much less than those of a roll of wire mesh of comparable length and can be accommodated without difficulty in the restricted space available at a working coal face. Moreover, rolls of such material can be handled as easily as the rolls of paper previously used.

Claims

1. A method of lining underground workings wherein an exposed surface of such working is covered by lengths of a single preformed flexible and reinforced laminated material which is unwound from rolls of such material by apparatus advancing along such working.

2. A method according to Claim 1 wherein said lengths of material are arranged in adjacent side-by-side relation and are joined together at their edges.

3. A method according to Claim 2 wherein said lengths of material are formed with a row of spaced holes adjacent to each edge thereof and said adjacent lengths are joined bymeans of links which enter said holes.

4. A flexible laminated material comprising at least one ply of paper which has been treated to render it substantially non-inflammable, and at least one layer of a reinforcement which has also been treated to render it substantially non-inflammable, bonded together by means of an adhesive substance which is also non-inflammable, the material as a whole being such as not to emit significant quantities of noxious substanes if exposed to fire, the material having a bursting strength sufficient to enable it to support loose pieces of material without further reinforcement.

5. A material according to Claim 4 wherein the reinforcement is sandwiched between two plies of paper.

6. A material according to Claim 4 or Claim 5 wherein the paper is rendered nonflammable by a non-water soluble fire retardent additive.

7. A material according to any one of Claims 4 to 6 wherein the paper has a weight in the range 70 to 80 grtams per square meter.

8. A material according to any one of Claims 4 to 7 wherein the reinforcement is flame-proofed jute hessian.

9. A material according to any one of Claims 4 to 8 wherein the adhesive substance is a hot melt adhesive.

10. A material according to any one of Claims 4 to 9 having a tear strength in excess of 400 Newtons/SOmm.

11. A material according to Claim 10 having a tear strength in the range 500 to 800 Newtons/50mm.

1 2. A material according to any one of Claims 4 to 11 formed into a roll and having a row of spaced holes adjacent to each edge thereof.

1 3. A method according to any one of Claims 1 to 3 wherein said material comprises a material according to any one of Claims 4 to 12.

14. A method of lining underground mine workings by paying out lengths of a material as claimed in any one of Claims 4 to 1 2 from rolls of such material carried by self-advancing mining machinery and forming adjacent lengths at their edges by means of tranversely arranged links.

1 5. A flexible reinforced laminated material substantially as hereinbefore described.

1 6. A method of lining underground workings substantially as hereinbefore described.

1 7. Any novel feature or novel combination of features disclosed herein.