GB2224053A - Mining method - Google Patents

Abstract

A process for mining coal in an unsupported manner utilizes a multiplicity of augered or otherwise bored holes 8 formed by an auger or other form of cutter 4 discharging its cut material on to a conveyor 5 and ultimately further on to a main conveyor 6 such holes 8 following a series of pilot holes 1 along which in umbilical 14 fashion, power, services and pulling equipment may be provided and which when spaced a working pitch 7 apart leave pillars 9 of unworked coal as roof supports which can subsequently be utilized by gasification. Holes 8 may also be used for storage of waste material, and may or may not be later gasified. <IMAGE>

Description

A METHOD OF MINING AND GASIFYING UNDERGROUND COAL This invention relates to the processes of mining and/or of gasifying coal from naturally occurring underground seams. Coal has for centuries been mined in a variety of ways and in some countries, and in a limited mannner some underground stocks or natural seams have been processed to form gas for external use.

In most present day cases coal mining operations are carried out mechanically along faces between adjacent service roadways (typically a distance of 200 metres) using mechanical or indenendent hydraulic roof supporting means in order t provide a safe working zone alons the active face for the extraction equipment and personnel.

In the UK now British Coal normally use the long wall system of mining which usually employs an hrdraulically powered self-advancing roof support device spaced approximately 1 metre apart along and supporting the roof above the face and the extraction equipment allowing all the remaining roof been the roadways in an area known as the "Goaf" to totally collapse.

Such a system uses very high capital cost equipment and is therefore very expensive to operate. Also the indirect cost of compensation for damage sustained by property, sewers, water mains and the like caused br subsidence after underground roof collapse is very high adding greatly to the cost of mined coal.

In areas where it is required to achieve Permanent support a column of unmined coal, known as a pillar, is left in the appropriate Position.

Additionally, it is often difficult for the more usual forms of underground coal extraction machinery to follow precisely undulating or faulted coal strata, thus leaving coal unmined or includins dirt in the mined coal.

This invention proposes a method of utilization to greatly reduce the uneconomical factors when mining coal, not-with-standing the fact that it is proposed that between 40 and 60% of the useable coal be left unmined at this stage, Possibly for later use by gasification.

According to the present invention it is propsed that a multiplicity of substanciallr parallel holes be augered or otherwise bored, forming tunnels through the coal seam substantially perpendicular to, and inter-connecting both incoming and outgoing roadways following implicitly a pre (directional controlsod) drilled pilot hole whilst at the same time said augering or other process causes the coal thus cut from its seam to be conveyed awar and subsequently deposited upon conventional underground main coal conveyors, such tunnelling is so arranged and spaced as to form a support pillar of coal between each augered or bored tunnel, said pillars to be subsequently gasified when all mining has ceased and the area used for other purposes and/or sealed off.

A specific embodiment of this invention will now be described by war of examPle with reference to the following drawings in which: Figure 1 shows in Plan view a section through the coal working seam and roadways.

Figure 2 shows a typical cross section of the coal seam with holes and pillars.

Figure 3 shows a longitudinal section through the working seam.

Figure 4 shows in section Plan the position of the various elements required in this proposal.

Figure 5 shows a longitudinal section through the working area to ground level.

Figure 6 shows a longitudinal section and cross section of dual auger or otherwise formed tunnels.

Referring to the drawings a series of pilot holes, 1 of appropriate diameter, are drilled substantially perpendicular to and ajar from the outgoing roadway 2 to join with the incoming roadway 3 using a direction controlled drilling machine 16 said drilling machine mar be positioned in either roadway and work in either direction. An auger (or other coal cutting device) 4 and an attached conveyor 5 are driven in like manner and direction to follow the pilot hole 1 whilst cutting coal in the seam 10. As cutting prosresses auger 4 and/or conveyor 5 mar be progressively extended in order that coal cut at the auger face 15 mar be transPorted back to the main conveyor 6 in the outgoing roadway 2.On arrival at the incoming roadways 3 the auger 4 and conveyor 5 may be withdrawn to begin the process again having been moved over one working pitch 7 or the combination auger 4 and conveyor 5 may be turned round to besin work in the opposite direction having-'moved over one workins..pitch 7 PrPVi,siop.having been made.

for the travelling conveyor 5 to discharge its load on to the main conveyor 6. Alternatively, the auger or other form of coal cutting device 4 mar be pulled by chain or wire rope or driven by, and power for it provided much in the manner of an umbilical 14 along the pilot hole 1 from the opPosite roadway. In this case the auger 4 need not be extended as work progresses, it being necessary only for the conveyor 5 to span the distance from auger 4 to main conveyor 6. Similarly, water for dust supprsrion and the like, hydraulic power lines, electrical cables and similar services mar be passed along the pilot hole 1 lav join the auger 4 or associated equipment.Referring to figure 2 - br correct spacing of the augered holes or tunnels 8 to form a workins pitch 7 the correct pillar 9 dimensions can be chosen and left unworked to fullY support the strata and conditions and loading between the working seams 10 and the surface 11 and mar be varied where such a course of action is required. Similarly, the auger 4 diameter may be changed to more accurately match the thickness of coal seam 10 being worked. Alternatively, one augered hole 8 may be placed above another to achieve the same object and the auger 4 may be driven in such directionas may be necessary to more accurately follow the seam thus causing both augered holes or tunnels 8 and 8a to converse or diverge as mar be required and as indicated in Fig 6.When the required quantity of coal has been removed by augering or other form of cutting from the zone Cor district) 12 bounded by main roadways 13 incoming roadways 3 outgoing roadway 2 and seam limit 17, the whole or part of the zone 12 mar at any convenient time be sealed off and if needed gasified. Alternatively, the holes or tunnels 8 remaining after coal extraction mar be filled, eg; by compaction means with or without bindin.g,agent,s.with unwanted waste material, mining residues and the like, thus still further reducing the effects of subsidence. It follows that if the correct materials are thus infilled, gasification at any future time would be possible and beneficial. Further, the process outlined will drastically reduce the cost of mined coal, will better utilize this national asset and improve environmental aspects of mining and or waste disposal. A further adaption of the method outlined could be employed in the technique of open cast coal recovery wherein the tunnels would he produced along coal seams but between open trenches rather than roadways as in underground extraction.

Claims (8)

1A method of underground mining, of coal ,wherein a multiplicity of substantially parallel holes are augered or otherwise bored through the coal seam substantially perpendicular to and interconnecting both incoming and outgoing roadways following implicitly a pre (direction controlled) drilled pilot hole whilst at the same time said augering or other boring process causes the augered or otherwise cut coal to be conveyed awar and subsequently deposited upon a conventional underground conveyor, such augering or borins is so arranged and spaced as to form a supporting pillar of coal between each augered or bored tunnel, said pillars to be subsequently gasified when all mining has ceased ano' the area used for other purposes or sealed off.

2 A method as in Claim l wherein a pilot hole is drilled in such a manner of such size so as to permit passage through said pilot hole of an auger (or other form of borer) drive pulling system including service supplies such as water for dust suppression air for gas dilution and removal and other use, hyraulic and electric power lines, communications and control cables and the like.

3 A method as in Claims 1 and 2 wherein one or more tiers of augered or otherwise bored tunnels may be produced in a directionally controlled fashion to match more accurately a coal seam thickness or distortion by convergence or divergence to or from each other during the auger journey from one roadway to its adjacent counterpart whilst at the same time maintaining the integrity of the roof supporting pillar of unmined coal.

r . I

4 A method as in Claims 1 to 3 wherein the auger or borer and its associated drive system are caused to constantly extend a coal transporting conveyor in order to continuously move cut coal from the point of cutting onto the main transport conveyor sited in one roadway.

5 A method as in Claims 1 to 4 wherein the drive system and its associated conveyor are continously extensible in order to transport coal from cut to conveyor.

6 A method as in Claims 1 to 5 wherein the augered or otherwise bored holes (tunnels) remaining when the coal mining process is completed may be filled with waste material.

7 A method as in Claims 1 to 6 wherein the coal remainins in the form of support pillars or otherwise, mar, when the working zone is properly prepared, be gasified in anr of a variety of ways in order to improve the utilization of coal resource.

8 A method as in Claims 1 to 7 and as depicted in the accompanying specification and drawings.