A MINING METHOD AND SYSTEM FOR USE THEREIN

FIELD OF THE INVENTION

This invention relates to a mining method, and more particularly, but not exclusively, to a mining method for use in underground coal mining. The invention also relates to a system for use in exercising the method of mining.

BACKGROUND TO THE INVENTION

Various continuous mining methods have been proposed in the past for purposes of increasing efficiency and output in coal and similar mining, but these all suffer from a number of disadvantages, including:

(i) Many continuous mining systems operate with a batching system, whereby the operation of the continuous mining machine is dependent on the arrival and departure of shuttle cars or other transportation means.

(ii) Certain continuous mining methods of clearing coal from the continuous mining machines, known as "continuous haulage" systems operate on the principle whereby the continuous mining machine discharges directly onto a continuous conveying system. It has been found that current arrangements are costly and ineffective in that the time required for manoeuvring the conveying system results in considerable down time. The current systems are furthermore heavy, which limits their application

in softer floor conditions; they are labour intensive and require extensive, costly maintenance. Current systems also lack further integration into the more stationary material clearance systems (the section conveyor system), further away from the continuous mining machine, but which also requires to be extended or shortened on a regular basis, depending on mining conditions and mining sequences.

(iii) Most continuous mining takes place in some or other form of "board and pillar" mining, be it square, rectangular or herring bone shaped.

The term "continuous mining machine" herein means a mining machine having a cutter head whereby ore is cut from an ore face during a single pass or multiple passes, and discharged from the machine, onto some sort of haulage device, be it batching or continuous.

OBJECT OF THE INVENTION

It is accordingly an object of the present invention to provide a novel mining method, and a system for use in exercising the mining method, which will at least partially overcome the abovementioned disadvantages, or will provide a useful alternative to existing mining methods and systems for use in exercising alternative mining methods.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method of mining that includes the steps of: providing a continuous mining machine; cutting at least one linear primary passage into an ore body; and cutting a plurality of secondary passages into the ore body, the secondary passages being disposed oblique relative to the primary passage; - whereby a roof zone of the ore body is supported by walls of material that separates the secondary passages.

The method also include the steps of: cutting an end passage extending substantially perpendicular from a primary passage; and cutting a plurality of oblique secondary passages extending between the primary passage and the end passage.

Preferably the secondary passages will extend from the primary passage at angles between 30 and 60 degrees.

There is provided for the distance between adjacent secondary passages to be selected in accordance with the width of the wall of material required to support the roof of the ore body. In one embodiment there is provided for the secondary passages to be relatively close to one another whereby long and thin walls of material are left behind to support the roof of the ore body. In an alternative embodiment the secondary passages may be spaced sufficiently apart to enable

the wall of material to be removed in entirety or part during a retreat mining process.

The method may also include the step of cutting at least one tertiary passage extending between adjacent secondary passages.

The secondary passages include entry ends at the junctions with the primary passage, and remote ends at the junctions with the ends passage.

There is provided for a plurality of tertiary passages to be cut in a retreat process starting at the remote end(s) of the secondary passage(s), and ending at the entry end of the secondary passage(s). During this process there is provided for wall sections or pillars to be selectively left behind between adjacent tertiary passages.

The mining method may also include the step of extracting ore continuously via the primary longitudinal passage.

The ore may be extracted from the ore body by way of a continuous haulage system that includes a conveyor belt. The method may further involve the use of a belt extender which houses the conveyor belt between a plurality of opposed rollers in a to an fro configuration so that when opposed rollers are moved towards one another, the belt is extended, and when opposed rollers are moved away form another the belt is retracted. The belt extender per se is known

technology, but the use of the belt extender in the particular integrated mining method has not been proposed before.

Preferably a continuous haulage system that can negotiate lower seams, down to 1.5m may be utilized. Preferably the height of the seams should not be less than 1.5 meters. The current equipment has been designed to be utilized in seam thicknesses between 1.5m and 5.5m, which is currently the maximum reach of continuous miners available in the market.

Various sequences of cutting the primary and secondary passages are possible, and it is intended that all such sequences should fall within the scope of the invention. For example, in one arrangement the secondary passages can be cut sequentially during advancement of the primary passages. Alternatively, the primary passage(s) could first be cut, and the secondary passages could be cut during retreat in a sequential manner from the remote end of the primary passage towards the entry end thereof.

The method of mining also includes the steps of inserting roof bolts and rib bolts (if necessary) by way of bolting systems as is described in more detail hereinbelow. More particularly, the roof bolts and rib bolts are inserted by way of an onboard rapid bolting system which is integrated with the continuous mining machine, and thus negates the need of removing the continuous mining machine before inserting roof and rib bolts by way of a separate bolting machine.

Also included in the method of mining is the integration of a plurality of further operational systems which is described in more detail hereinbelow, the operational systems including: a continuous haulage system;

- a water supply system;

- a power supply system; and

- a ventilation system.

The method may also include the step of crushing and sizing of ore at a loading zone. For example, a crusher and/or sizer could overlie the conveyor belt at the loading zone.

According to a further aspect of this invention there is provided a totally integrated mining system, suitable for use in performing the method of mining described hereinbefore, the integrated mining system includes: a continuous mining machine suitable for cutting at least one primary longitudinal passage into an ore body, the continuous mining machine also being adapted to cut secondary passages extending from the primary passages, the secondary passages being disposed at angles between 0 and 360 degrees relative to the primary passage.

Preferably the continuous mining machine will be adapted to cut secondary passages disposed at an angle of between 30 and 60 degrees relative to the primary passage.

The continuous mining machine may also be adapted to cut tertiary passages between adjacent secondary passages, the tertiary passages being disposed at angles between 30 and 60 degrees relative to the secondary passages.

The integrated mining system may also include a continuous haulage system and a section conveyor for extracting ore from a cutting face via the primary passage.

There is provided for the continuous haulage system to remove material from the cutting face and to dispose the ore onto the section conveyor, from the head end of which the ore is cleared by way of the mine's main conveyor system.

The section conveyor may include a motorized tail end, which allows the section conveyor to be extended while the conveyor is running. There is also provided for the motorized tail end to carry the power supply auxiliaries required for the section conveyor, including a transformer and switchgear. The section conveyor tail end may also include a conveyor belt support structure launcher, which allows conveyor belt support structures to be installed mechanically as and when required, and while the conveyor system is operational. The section conveyor is preferably driven by a variable speed drive that prevents violent behavior of the conveyor system under starting and stopping conditions, limiting the starting tension in the conveyor system to the maximum full load running tension.

The continuous haulage system is also adapted to carry any one or all of the following auxiliary systems:

Ventilation system for supplying fresh air to the cutting face;

Power supply system for supplying power to the continuous mining machine;

Water supply system for supplying water and coolant to the continuous mining machine; and

Data communication system between the various pieces of equipment employed in the section.

There is also provided for the integrated mining system to include a continuous bolting mechanism that is adapted to install supporting roof and rib bolts as the continuous mining machine progresses along a passage that is being cut. Preferably the bolting mechanism is located onboard the continuous mining machine.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described by way of an example only, and without limiting the scope of the invention, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of a mining method illustrating the various cutting sequences in accordance with the invention;

Figure 2 is a schematic representation of the sequence in which cuts are made in accordance with the invention;

Figure 3 is a schematic representation of an integrated cutting system used in the method of mining shown in figure 1 ;

Figure 4 is a schematic illustration of a belt storage and extending device used as part of the integrated mining system; and

Figure 5 is a schematic illustration of a support system for supporting a conveyor belt and utilities in the method of the invention.

DETAIL DESCRIPTION OF THE INVENTION

Referring to the drawings, in which like numerals indicate like features, a non- limiting embodiment of the method in accordance with the invention comprises cutting primary 20, secondary 30 and tertiary 40 passages in an ore body 10.

In the specific embodiment shown in figure 1 , two primary passages, 21 and 22, has been cut into the ore body 10, and a plurality of secondary passages 30 have been cut between the two primary passages 21 and 22. The two primary passages 21 and 22 and the secondary passages 30 there between constitute the primary mining activity. It can be seen that large support pillars 50 are left to

support the roof in this area, thus rendering the primary mining area structurally stable. Primary mining therefore takes place at sections where high safety factors are adhered to.

Each primary passage 21 and 22 extends towards a predetermined depth into the ore or coal body, and a generally transverse end passage 25 is cut from the end zone of the primary passages in a direction substantially perpendicular relative to the primary passages 21 and 22. This is followed by cutting a number of secondary passages 31 , 32 and 33 into the ore body, which constitute the commencement of the secondary mining process. The secondary passages, 31 , 32 and 33, are angularly displaced relative to the primary passage 21 , and in this example are approximately at a 45 degree angle relative to the primary passage 21. Initially large wall sections 51 are left between adjacent secondary passages, for example as shown between passage 32 and 33.

Tertiary passages 40 have been cut between secondary passages 31 and 32, and smaller pillars 52 are left, whilst the bulk of original pillar 51 has been removed so as to optimize coal recovery. The tertiary passages 40 are disposed at approximately 45 degree (this angle may be optimized for specific conditions) angles relative to the secondary passages 31 and 32.

The sequence in which the mining method is executed is shown in figure 2, and follows the alphabetic notation from a to z. The primary mining phase comprises cutting sections of the primary passages 21 and 22, followed by cutting a secondary passage there between. The iterative sequence is illustrated by steps

a-b-c, d-e-f, g-h-l, j-k-l and m-n-o. Once the remote end of the primary passages reaches the predetermined end zone, a transverse passage 25 is cut in the direction shown by Arrow B, and in the sequence denoted by p. After the transverse passage 25 has been cut, the first 31 and second 32 secondary passages are cut in sequence q-r. These passages are cut from the primary passage 21 towards the transverse passage 25. Once two adjacent secondary passages have been completed, tertiary passages 40 are cut between the secondary passages so as to remove additional coal or ore. The tertiary passages are cut in retreat mode in sequence s-t-u-v-w-x-y, and subsequent cuts are thus made away form the danger area where pressures from the overlying strata are the highest. Once the tertiary cuts have been made, and only the pillars 52 have been left behind, a further secondary passage 33 are cut in sequence z, and the process of removing additional coal or ore via secondary mining is repeated. The general directions of the primary and secondary cuts are indicated by arrows A, B and C.

It will be appreciated that the remote ends of the secondary passages, 31 , 32 and 33, are the areas exposed to the highest pressure from the overlying strata, taking into account the beam of the overburden overlaying the mining area. Since mining in the secondary phase takes place in retreat mode form this danger zones, i.e. via cuts s to y, the continuous mining machine, equipment and persons involved in the process are continuously moving away from the danger area towards the more stable primary passages 21 and 22. While cuts s to y are made, the continuous mining machine is continuously protected by a solid pillar

adjacent the secondary passageway 32, as well as by a pillar 52 on the right- hand side of the cutting apparatus whilst making the tertiary cuts.

Mining is of course not limited to the particular configuration, and many variations may be applied. For instance, mining may also take place towards the opposite side of the primary passages 20, so that additional secondary passages will extend from primary passage 22. Also, the specific angles of the secondary passages relative to he primary passages can be adapted in accordance with the specific composition and shape of the coal or ore body to be mined as well as specific site conditions. The underlying principle will however remain the same, in that secondary mining will always be done away from the high-pressure danger zone towards the primary passages.

A schematic illustration of the integrated total in-section mining system 70 used in the above mining method is shown in figure 3. The integrated total in-section mining system 70 includes a continuous mining machine 71 and a mobile tail end 72. The continuous mining machine 71 incorporates an integrated bolting system. The mobile tail end includes a steerable tail end of the section belt, a structure launcher, a transformer and switchgear as well as a traction system that is operatively connected to the continuous mining machine 71 , by a system known in the art, the so-called Flexiveyor system 75, in order for coal or ore removed by the continuous mining machine 71 to be removed by way of a section conveyor 76 extending from the tail end 72. The mobile tail end 72 also allows for the section conveyor 76 to be extended while the conveyor is running. The conveyor belt extender 80 utilized in this particular embodiment is shown in

figure 4, and houses a conveyor belt 81 between a plurality of opposed rollers 82 in a to and from configuration so that when the opposed rollers 82 are moved towards one another, the belt is extended and vice versa.

The section conveyor tail end 72 may also include a conveyor belt support structure launcher (not shown), which allows conveyor belt support structures to be installed mechanically as and when required, and while the conveyor system is operational. Conveyor belt support structures 81 described above is shown in figure 5 and could be in the nature of a support device 90 which provides a plurality of cantilevered support arms, 91 and 92, which extend generally horizontally at different levels. A first tier of support arms 91 could for example support a return portion of the conveyor belt 81 , a second tier of support arms 92 could support the load-carrying portion of the conveyor belt 81. The support structure 90 will be expandable from a closely stacked configuration to a spaced configuration as the length of the conveyor belt extends, and will be launched by way of the support structure launcher that is linked to the section conveyor tail end 72.

The integrated system, and in particular the continuous mining system 71 , also includes an onboard bolting mechanism (not shown). Generally, supporting roof and rib bolts need to be installed whilst cutting a passage into an ore body. The roof bolts connect the roof layers to one another, thus preventing sagging of the roof section. The rib bolts increase the stability of the sidewalls in areas where the competence of the sidewalls are in question. Previously one had to cut a passage of predetermined length, and then had to remove the cutting machine so

as to allow the installation of roof and rib bolts by way of a separate roof/rib- bolting machine in a sequential method. The onboard bolting mechanism supports the continuous cutting process in that roof bolts are installed as the cutting machine cuts a new passage. Roof and rib bolts are thus installed shortly after a cut has been made, which also prevents bed separation that appears in roof layers when an open roof stands unsupported for extended periods and it delays the weathering of sidewalls or ribs. The onboard bolting functionality clearly constitutes a major improvement in efficiency and safety.

Not shown in the drawings, the integrated mining system also includes a variety of secondary logistic support systems, which are freestanding from the continuous mining machine, and primary support systems, but which are designed for effective operation of the integrated mining system. These secondary logistical support systems include the following:

Consumable supply system wherein all consumables are palletized and fed to the mining system one a regular basis;

Utility vehicles are specifically adapted for use in the integrated mining system, and perform a variety of functions including supply of consumables to cutting machine, deploying the conveyor belt structure, erecting and moving ventilation structures, replenishing section conveyor belting, moving around parts and components, moving around tools, erecting stonedust barriers and general cleaning of the production section. It will be appreciated that these vehicles can be of many different designs, but that in accordance with the invention the impetus is on a

complete integrated system that includes utility vehicles that are customized to match the requirements of the system as a whole; Minimized manhandling functionality, which entails that all components or devices used in the integrated mining system that are not self-propelled can be moved, carried or maneuvered by the utility vehicles as described above.

The inventor is of the opinion that the essence of this invention can be summarized as follows:

- The method has been changed from board and pillar to the linear mining process;

- The continuous mining machine can cut for extended periods in one direction, uninterrupted, due to inter alia the use of a continuous haulage system, linked with an extendable section conveyor system, as well as introduction of an onboard bolting system;

- The cutting machine can cut secondary passages in any direction relative to the primary passage(s) thus resulting in increased flexibility, for example should there be a geological disturbance, as there are more degrees of freedom when selecting an appropriate mining sequence and pattern for a predetermined body of ore;

- Tertiary passages are cut in a retreat zoning process, thus always moving away from the danger zone;

- Most manhandling tasks in this section have been eliminated by the introduction of utility vehicles and the specific sequence of assembly of the total system;

- The mining system is assembled in such a way that it forms a harmonious system that mines in a predetermined fashion, without abrupt movements of any part of the system; it basically moves forward at a rate of one meter every time period, depending on seam thickness, until it reaches the furthest point of cut, then either reverses out of the heading or removes the pillar as previously described;

- The secondary support systems in the section are set up in such a way as to afford the continuous mining machine the ability to cut for extended periods, uninterrupted;

- The utility vehicles will bring consumables to the cutting machine whenever required;

- The utility vehicles will install or remove conveyor belt support structure whenever required for the system to advance or retreat;

- The utility vehicles will replenish or remove conveyor belting from the system whenever required;

- The utility vehicles will install ventilation structures whenever required;

- The utility vehicles will bring to the machine or any other position in the section tools required to specific jobs; and

- The utility vehicles will assist with the maintenance tasks in the section, by supplying hydraulic power take offs and carrying spares, lubricants, components, etc.

It will be appreciated that the above is only one embodiment of the invention, and that there may be many variations in detail without departing from the spirit and the scope of the invention.