AP326A

AP326A - Non-explosive mining method and apparatus using circular saws.

Info

Publication number: AP326A
Application number: APAP/P/1992/000359A
Authority: AP
Inventors: Marc Octave Rene Ghilslain Buyer BUYENS; Anthony Ian Smith; Marthinus Johannes Taljaard; John Redvers Hunt; Peter Lance Desmond O'toole; Damien Pennefather; Harry Tudor Tucker; Graham Walter Reeks; Timothy Patrick Gerard Addison; Paul William Butler-Smith; Orrie Fenn
Original assignee: Advanced Mining Software Ltd
Priority date: 1991-01-30
Filing date: 1992-01-29
Publication date: 1994-03-17
Also published as: ZA927962B; AP9200359A0

Abstract

A non-explosive mining apparatus has a series of modules

Description

BACKGROUND TO THE INVENTION

This invention relates to non-explosive mining, and in particular to a selective nonexplosive mining method.

The conventional hard rock mining system involves blasting to break fragments of rock from the working face. The fragments are then recovered and transported to surface, possibly after initial crushing underground, for subsequent processing to liberate the valuable minerals which they contain. This conventional mining system is extremely inefficient in a number of respects.

Firstly, when blasting takes place, it is necessary to evacuate personnel at least from the immediate area of the blast.

Secondly, such personnel can only return to the mine after a certain period of time has lapsed because of the possible existence of dangerous gases and possibility of rockfalls as a result of the blast.

Thirdly, having blasted the face, it is a time-consuming and labour intensive process to recover all the fragmented material for subsequent transportation to surface.

Fourthly, the blasting technique is non-discriminatory in the sense that not only the potentially valuable mineral reef but also a good deal of waste material is broken

-SCO 'ι <j from the face at each blast. All the fragmented material must be transported to surface for subsequent processing. The necessity to process large volumes of waste material clearly places a heavy burden on the surface processing equipment which must, in any event, have the capacity to process all the material which arrives. Much lower capacity equipment could be used to perform the final processing operations if only potentially valuable reef were recovered from the mine.

Furthermore, blasting generates fines carrying potentially valuable ore which fall into any cracks in the footwall or other rock faces. Without blasting, such fines are not created, nor are cracks and accordingly, there is less loss of such fine particles in gold.

With these serious disadvantages of an explosive mining technique, it is an object of the invention to provide a non-explosive mining apparatus and method.

SUMMARY OF THE INVENTION

A first aspect of the invention provides a non-explosive mining apparatus comprising a plurality of modules each having a base capable of movement over a footwall in a mine working and each carrying a portion of a rail, the modules being locatable side-by-side with one another with the rail portions in alignment so as to form a continuous rail extending generally parallel to the working face in the mine working, and at least one carriage which is movable along the rail and which carries a circular saw that can be driven in rotation to form a cut in the working face as the carriage moves along the rail.

Preferably, the modules are connectable to one another in side-by-side relationship.

Each module may have a skid base designed to slide over the footwall in the mine

APO00326 working.

In the preferred embodiment, means are provided on the or each carriage for tilting and slewing the saw. Conveniently, the saw of the or each carriage is carried by an arm having a first portion which is pivoted to the carriage about a first, lateral axis and a second portion which is pivoted to the first portion about a second, upright axis, and wherein hydraulic cylinders are provided to pivot the first portion of the arm, relative to the carriage, about the first axis to tilt the saw, and to pivot the second portion of the arm, relative to the first portion of the arm, about the second axis to slew the saw. A further hydraulic cylinder may be provided on the or each carriage to raise and lower the arm relative to the carriage. Conveniently also, the or each carriage includes a traverse drive operable to drive the carriage along the rail, and rollers arranged to bear on different parts of the rail to guide the movement of the carriage along the rail.

For correct alignment of the modules and rail, each module in the preferred embodiment carries a guide slipper, the guide slippers aligning with one another when the modules are arranged in side-by-side relationship, and the apparatus includes an elongate guide member which is connectable to elongate props that are arranged upright between a hanging wall and a footwall in the mine working, the guide member being cooperable with the guide slippers of the modules.

To allow for multiple passes, the guide slippers can connected to their respective modules by pivoted arms.

There may be a plurality of carriages, at least one saw carried by a carriage being arranged to make a relatively high cut in the working face and at least one other saw carried by another carriage being arranged to make a relatively low cut in the working face. Preferably, the apparatus also includes further saws, carried by further

BADOR1GINAL $ carriages, arranged to make intermediate cuts in the working face between the relatively high cut and the relatively low cut.

A second aspect of the invention provides a method of non-explosive mining, the method comprising the use of the apparatus summarised above to form cuts at different elevations in a working face in a mine working, and subsequently the use of rock breaking machinery to break out rock from the working face between the cuts.

In a case where there is a plurality of carriages each with a saw, the method comprises the use of the summarised apparatus to form a high level cut in the mining face at the level of the hanging wall, to form a low level cut in the mining face at the level of the footwall, and to form intermediate cuts in the mining face above and/or below an ore-bearing reef between the high and low level cuts. This method may then involve the further steps of separately breaking out of the mining face:

a) barren rock located between the high level cut and the cut above the reef and between the low level cut and the cut below the reef; and

b) ore-bearing rock from between the intermediate cuts.

The ore-bearing rock can then be recovered for processing and the barren rock can be used for backfilling purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with

AP Ο Ο Ο 3 2 6 reference to the accompanying drawings in which:

Figure 1	shows a plan view of a mine working in which apparatus of the invention is deployed and in which mining in accordance with the method of the invention is taking place;
Figure 2	shows a perspective view of a single module without a carriage thereon;
Figure 3	shows a perspective view of a single module with a carriage mounted thereon;
Figure 4	shows a plan view of apparatus of the invention;
Figure 5	shows a side view of the apparatus of the invention, illustrating only the saw which makes a low cut; and
Figure 6	shows a side view similar to that of Figure 5, but in this case illustrating only the saw which makes a high cut.

DESCRIPTION OF AN EMBODIMENT

Referring firstly to Figure 1, there is shown a mine working 10, in this case a mine stope. The working face is indicated with the numeral 12 and mining is taking place in the direction of the arrow 14. As is conventional in a gold mine the hanging wall in that area of the stope which is already mined out is supported by means of elongate props 16, at least the first few rows nearest to the face 12 being hydraulic props. Adjacent the gullies 18 at the sides of the stope, pack supports 20 are provided.

The apparatus of the invention includes a series of individual modules 22, one of which is illustrated in Figure 2. The modules are arranged side-by-side with one another as seen in Figure 1 and are connected to their neighbours by means of bolts passing through aligned holes 24 (see Figure 2).

Each module 22 is of robust steel construction and has a skid base 26 shaped as shown. Towards the rear edge of the skid base 26 there is a structure 28 which carries a rail 30 and which carries two piers 32. Each pier 32 accommodates an hydraulic ram of which the pistons 34 and bearing pads 36 are visible in Figure 2.

The rear upper edge of the rail 30 (not visible in the drawings) is formed as a toothed rack. The rail 30 includes spaced apart reinforcing pillars 38 which carry a V-shaped member 40. When the various modules 22 are connected together as shown in Figures 1 and 4, the rails 30 align with one another to form a continuous rail extending in a direction that is parallel to the face 12.

Figure 3 illustrates a carriage 42 mounted on a module 22. Referring to Figure 5 in particular, it will be seen that the carriage 42 has rollers 37, 39 and 41 which engage the top of the rail 30 from above, the top of the rail from the sides and the V-shaped member 40 of the rail respectively. In addition, the carriage has a traverse drive 50 which engages the rack at the rear upper edge of the rail 30. The drive 50 can be actuated to drive the carriage along the rail 30. Of course, when the modules are connected together as in Figures 1 and 4, the drive 50 of the carriage can be used to traverse the carriage, in a direction parallel to the face 12, from one module to the next. It will be noted that the rollers 37, 39 and 41 are arranged to guide and

AP0 00 3 2 6 support the carriage on the rail during such movement of the carriage.

The carriage 42 carries an arm 44 which has two portions 44A and 44B. The portion 44A, in this specification referred to as a tilt frame, is pivoted to the carriage about a lateral pivot 46 while the portion 44B, in this specification referred to as a ranging arm, is pivoted to the tilt frame 44A about an upright pivot 48. A first hydraulic cylinder 51 acts between the tilt frame 44A and the carriage 42 and serves as a tilt cylinder. It will be appreciated that extension or retraction of the cylinder 51 will cause the tilt frame to tilt up or down. A second hydraulic cylinder 52 acts between the tilt frame 44A and the ranging arm 44B and serves as a slew cylinder. In this case, it wiil be appreciated that extension or retraction of the cylinder 52 will slew the ranging arm in an arc from side to side.

In addition to the tilting and slewing movements described above, the tilt frame 44A can be raised and lowered relative to the carriage 42. This is achieved by means of an upright hydraulic cylinder 43 connected between the carriage 42 and the tilt frame. Upright guide posts 45 pass through bearing blocks 47 and serve to guide the up and down movement of the tilt frame relative to the carriage.

The end of the ranging arm 44B carries a circular saw comprising an hydraulic motor 54 and a reduction gearbox 56 supplying a rotational drive to a circular saw blade 58. The nature of the blade drive is explained in detail in a copending patent application filed simultaneously with the present application.

Spanning across the piers 32 is a channel-shaped guide slipper 60. Referring to Figure 5, there is shown a typical hydraulic prop 16 in the first row of such props nearest to the face 12. A bracket 62 is clamped to each of the props 16 in the row and the brackets support a continuous guide member 64 which sits between the cheeks of the guide slippers. With this arrangement it is possible to set up the

ί) Ϊ C ίΐ Ο ο Λ interconnected modules 22 correctly in relation to the props 16 and the face 12 and to ensure that the modules are advanced, and remain, parallel to the face.

Referring again to Figure 1, a number of carriages, each with their own circular saws, are arranged on the interconnected modules 22. Each such carriage can be driven independently of the others by virtue of an independent hydraulic supply from a power pack 66 located further back in the stope. The various hydraulic hoses seen in Figures 1 and 3 supply pressurised hydraulic fluid to power the traverse drive 50 of the carriage, the tilt and slew cylinders 51 and 52, the upright cylinder 43 and the hydraulic motor 54, with independent hydraulic controls being provided for each of these functions.

Figure 5 shows a carriage 42 which carries a circular saw arranged to make a low cut into the face, i.e. a cut at the level of the footwall. In this case, the tilt cylinder 51 has been actuated to tilt the saw blade 58 downwardly relative to the horizontal so that a downwardly inclined cut is made into the face 12. It will be noted that no part of the circular saw protrudes below the lower surface of the blade itself, thereby obviating the possibility of the blade fouling during rotation.

In Figure 5, the angle of downward tilt of the saw blade 58 is about 10°. The tilt cylinder 51 is capable of tilting the saw blade upwardly, past the horizontal, to an angle of about 10° above the horizontal, as indicated by the broken line 70. If, for instance, the stope width is arranged in relation to a mineral reef 72 which it is desired to extract, it will be seen that cuts may be made above and below the reef using the saw blade 58 in the Figure 5 configuration and at different tilt angles. It will also be seen that the footwall 74 of the stope takes on a stepped configuration as a result of the downward tilt of the saw blade 58 when it makes successive low cuts at the level of the footwall.

AP Ο Ο Ο 3 2 6

Figure 6 shows another carriage 42 in which there is a reversal of the configuration of Figure 5. In this case, the tilt frame and ranging arm are inverted with respect to their orientations in Figure 5, such that the saw blade 58 is capable of making an upwardly inclined high cut, i.e. at the level of the hanging wall 78. Once again, the tilt cylinder 51 can be actuated to tilt the saw blade 58 in Figure 6 downwardly relative to the horizontal, again with about 20° of possible angular movement. Once again, with successive high cuts formed as illustrated in Figure 6, a stepped configuration of the hanging wall results.

From the previous description of the action of the upright cylinder 43, it will be appreciated that the saw blade 58 can, in addition to being tilted, be raised and lowered to any intermediate height between the hanging wall and the footwall that is desired. Thus it is possible to make a cut into the face 12 at any chosen height in the width of the stope.

The cutting action of each saw blade is initiated by using the slew cylinder 52 to swing the blade in an arc and that cutting will only start once the modules 22 and other equipment are firmly anchored by extending the pistons 34 to urge the bearing pads 36 firmly against the hanging wall. Figure 4 shows a blade 58 in the Figure 6 configuration, making a high cut, on the right hand side and a blade 58 in the Figure 5 configuration, making a low cut, on the left hand side. Figure 4 also illustrates inoperative positions of the blades 58 in broken outline. From the inoperative positions, the blades are slewed counterclockwise in Figure 4 to bring them to the full line, operative positions. Thereafter, with the blades rotating and the carriages driven along the rail in a direction from right to left by the traverse drives 50, cuts are made in the working face by the blades. The high cut is indicated in Figure 4 with the numeral 80.

There may of course be a number of carriages traversing the rail, one after the other, the blades associated with the carriages making cuts at different heights, depending on the exact mining cut pattern that is required. For instance, cuts may be made simultaneously at the level of the hanging wall, at the level of the footwall and at spaced levels above and below a reef situated between the hanging wall and the footwall.

Referring again to Figure 1, there are shown two rock breaking machines 100 and 102. Each of these machines is independently driven along the face 12, for instance on tracks or wheels, and carries pneumatic or hydraulic impact rock breaking moils 104 which attack the working face 12 after the carriages 42 have passed and the necessary cuts have been made by the saw blades 58.

The action of the moils is to break out the rock from between the previously formed cuts. Figure 1 shows the moils of the first machine 100 breaking out waste rock from above and below the reef which it is desired to recover. The second machine 102, which pursues the first machine 100, then breaks out the reef between relevant cuts made previously by the saw blades 58. A movable barricade 106 is erected between the two machines so that rock which they break out does not get mixed up.

The waste rock broken out by the first machine 100 is transported back from the face and can be used for backfilling old mine workings. The mineral rich rock broken out by the second machine 102 is moved into the gulley 18 for eventual transportation to the surface, by conventional means, for subsequent processing to recover the mineral content.

After all the carriages have traversed the face 12, the necessary saw cuts have been made and the rock has been broken out, it is necessary to move the interconnected modules 22 forwards to a new positions. This is achieved by releasing the pistons

AP Ο Ο Ο 3 2 6

34, and pushing the modules further towards the face 12. The provision of smooth skids will enable the modules 22 to be pushed forwards without too much difficulty, particularly bearing in mind the relatively regular footwall which has previously been formed by the low cuts into the mining face.

Referring to Figure 4, it will be seen that the guide slippers 60 are pivoted to the ends of arms 61. The opposite ends of the arms 61 are pivoted at 63 to the rails 30 of the modules 22. The mounting of the arms 61 permits them to pivot between the full line and broken line positions seen in Figure 4. A comparison of the broken line positions of the arms 61, guide member 64 and props 16 with their full line positions in Figure 4 indicates that the modules 22 can be moved forwardly through a limited distance after each pass across the face 12. Thus it is possible, given one position of the props 16, to make two passes across the face 12 before it becomes necessary to instal a new row of props, whereafter a further two passes can be made across the face.

When compared to conventional blasting technology, the system described above has numerous advantages. Firstly, since there is no blasting, it is anticipated that there will be no need to evacuate personnel from the mine while mining is in progress, with the result that mining can take place on a continuous basis. Secondly, there is little likelihood of dangerous gases being generated by the sawing operation. Thirdly, it is possible to discriminate between mineral-bearing and barren rock so that only the mineral-bearing rock need be transported to surface for subsequent processing, with the barren rock being available in the mine working to serve a valuable backfilling function.

Fourthly, since there is no blasting, less ore-bearing fines are generated and consequently there is less gold loss while using this invention.

Claims

1.

A non-explosive mining apparatus comprising a plurality of modules each having a base capable of movement over a footwall in a mine working and each carrying a portion of a rail, the modules being locatable side-by-side with one another with the rail portions in alignment so as to form a continuous rail extending generally parallel to the working face in the mine working, and at least one carriage which is movable along the rail and which carries a circular saw that can be driven in rotation to form a cut in the working face as the carriage moves along the rail.

2.

A non-explosive mining apparatus according to claim 1 wherein the modules are connectable to one another in side-by-side relationship.

3.

A non-explosive mining apparatus according to either one of the preceding claims wherein each module has a skid base designed to slide over the footwall in the mine working.

4.

A non-explosive mining apparatus according to any one of the preceding claims wherein means are provided on the or each carriage for tilting and slewing the saw.

AP Ο Ο Ο 3 2 6

5.

A non-explosive mining apparatus according to claim 4 wherein the saw of the or each carriage is carried by an arm having a first portion which is pivoted to the carriage about a first, lateral axis and a second portion which is pivoted to the first portion about a second, upright axis, and wherein hydraulic cylinders are provided to pivot the first portion of the arm, relative to the carriage, about the first axis to tilt the saw, and to pivot the second portion of the arm, relative to the first portion of the arm, about the second axis to slew the saw.

6.

A non-explosive mining apparatus according to claim 5 wherein a further hydraulic cylinder is provided on the or each carriage to raise and lower the arm relative to the carriage.

7.

A non-explosive mining apparatus according to any one of the preceding claims wherein the or each carriage includes a traverse drive operable to drive the carriage along the rail.

8.

A non-explosive mining apparatus according to any one of the preceding claims wherein the or each carriage includes rollers arranged to bear on different parts of the rail to guide the movement of the carriage along the rail.

9.

A non-explosive mining apparatus according to any one of the preceding claims wherein each module carries a guide slipper, the guide slippers aligning with one another when the modules are arranged in side-by-side relationship, and the apparatus including an elongate guide member which is connectable to elongate props that are arranged upright between a hanging wall and a footwall in the mine working, the guide member being cooperable with the guide slippers of the modules.

10.

A non-explosive mining apparatus according to claim 9 wherein the guide slippers are connected to their respective modules by pivoted arms.

11.

A non-explosive mining apparatus according to any one of the preceding claims and including a plurality of carriages, at least one saw carried by a carriage being arranged to make a relatively high cut in the working face and at least one other saw carried by another carriage being arranged to make a relatively low cut in the working face.

12.

A non-explosive mining apparatus according to claim 11 and including further saws, carried by further carriages, arranged to make intermediate cuts in the working face between the relatively high cut and the relatively low cut.

13.

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A non-explosive mining apparatus according to claim 11 or claim 12 wherein the carriages are individually movable along the rail.

14.

A method of non-explosive mining, the method comprising the use of a nonexplosive mining apparatus according to any one of the preceding claims to form cuts at different elevations in a working face in a mine working, and subsequently the use of rock breaking machinery to break out rock from the working face between the cuts.

15.

A method of non-explosive mining, the method comprising the use of a nonexplosive mining apparatus according to claim 12 to form a high level cut in the mining face at the level of the hanging wall, to form a low level cut in the mining face at the level of the footwall, and to form intermediate cuts in the mining face above and below an ore-bearing reef between the high and low level cuts.

16.

A method of non-explosive mining according to claim 15 and comprising the further steps of separately breaking out of the mining face:

b) ore-bearing rock from between the intermediate cuts.

< Λ .f

17.

A method of non-explosive mining according to claim 16 and comprising the further steps of recovering the ore-bearing rock for processing and of using the barren rock for backfilling purposes.