WO2013175383A1

WO2013175383A1 - Slope design

Info

Publication number: WO2013175383A1
Application number: PCT/IB2013/054131
Authority: WO
Inventors: David JANSEN VAN RENSBURG
Original assignee: Jansen Van Rensburg David
Priority date: 2012-05-21
Filing date: 2013-05-20
Publication date: 2013-11-28

Abstract

An open pit mine slope arrangement, which includes at least one constant incline mine slope and a plurality of rockfall barriers arranged on the at least one constant incline mine slope. A method of mining an open pit mine, which includes mining an ore body by removing the ore body and leaving a constant incline mine slope and providing a plurality of rockfall barriers on at least one constant incline mine slope.

Description

SLOPE DESIGN

FIELD OF THE INVENTION This invention relates to open pit mine slope design. More particularly, the invention relates to an open pit mine slope arrangement and to a method of mining in an open pit mine.

BACKGROUND OF THE INVENTION

In open pit mining, the slope design in which batters and berms/benches are constructed is well known. In particular, as open pit mines were mined deeper, the batter and berm technique of slope design became a standard to contain rockfalls, especially as slopes in mines became steeper.

However, the batter and berm technique leads to wastage due to the additional material that has to be mined to construct the batters and berms.

It is an object of the present invention to address at least some of the shortcomings of the current slope design techniques.

SUMMARY OF THE INVENTION

According to one aspect of the invention, in a geological area containing an ore body where an open pit mine could be established, there is provided an open pit mine slope arrangement, which includes

at least one constant incline mine slope; and

a plurality of rockfall barriers arranged on the at least one constant incline mine slope.

It is to be appreciated that the constant incline refers to a batterless and bermless incline. In one type of open pit mine, a slope base may be aligned with a lower contact of an ore body, the slope base running at ant one of a constant incline aligned with the ore body and at an average slope angle. The slope angle may be determined by the use of one or more of three slope design methodologies namely, Factor of Safety, Probability of Failure or Risk Consequence/Reward.

In one embodiment, the plurality of rockfall barriers may extend in a plane transversely upwardly from the slope base and arranged at a slight incline relative to the contours of the constant incline mine slope. Each rockfall barrier may define an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which defines the rock feed-off points.

The plurality of rockfall barriers may be arranged in rows with the rock feed-off points of all the rows being aligned with each other.

Ends of the plurality of rockfall barriers in a row may open onto a row of strike barriers in which the rocks may be arrested. The row of strike barriers may be arranged along a contour of the constant incline mine slope, the strike barriers extending in a plane transversely upward from the slope. The strike barriers may be in the form of rockfall attenuators, arranged to be loose at the side proximate the slope with rockfall netting running over the constant incline slope, the rockfall netting having receiving ends proximate the strike barriers, in use receiving rocks underneath the netting and attenuating their movement down the slope.

The rows of strike barriers may be aligned underneath each other along the slope. The slope arrangement may thus define a rock flow path across the contours along the rockfall netting and underneath the strike barriers and rockfall netting. Rocks are collected on a specifically designed geotechnical catch bench or on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

In another embodiment the plurality of rockfall barriers may extend in a plane transversely upward from the slope base and arranged at a slight incline relative to the contours of the constant incline mine slope. Each rockfall barrier may define an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which defines the rock feed-off points.

The rockfall barriers may be arranged in rows with the rock feed-off points of one row of barriers being interspersed with apexes of the next lower row of rockfall barriers.

In another embodiment, the rockfall barriers may be in the form of rockfall netting sheets attached at their sides to the slope to define a rock flow path underneath the sheets along the mine slope.

The sheets may be arranged next to each other, being fixed to each other on their sides.

The lower ends of the rockfall netting may define rock feed- off points, where rocks can collect on any one of a specifically designed geotechnical catch bench and on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

In another embodiment, the rockfall barriers may be in the form of rockfall attenuators comprising upright rockfall barriers of which the lower ends define rockfall netting drapes running over the slope.

The rockfall barriers may be arranged along the contours of the slope with a plurality of rockfall barriers being provided down to the bottom of the pit. The end of the drape of the lowest rockfall barrier may define a rock feed-off point where rocks may collect on a specifically designed geotechnical catch bench or on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

The open pit mine slope arrangement may extend around all the pit slopes, including those slopes that do not contain ore. The pit slopes may be constructed at any one of a constant incline aligned with the ore body and at an average slope angle.

In a geological area containing an ore body where an open pit mine could be established, the invention extends to a method of mining an open pit mine, which includes

mining an ore body by removing the ore body and leaving a constant incline mine slope;

providing at plurality of rockfall barriers on at least one

constant incline mine slope.

It is to be appreciated in the method that the constant incline mine slope refers to a batterless and bermless incline.

In one type of open pit mine removing the ore body may include leaving a slope base which is aligned with a lower contact of an ore body, the slope base running at any one of a constant incline aligned with the ore body and at an average slope angle.

In one embodiment, providing a plurality of rockfall barriers on at least one constant incline mine slope may include providing rockfall barriers which extend in a plane transversely upwardly from the slope base and which barriers are arranged at a slight incline relative to the contours of the constant incline mine slope, each rockfall barrier defining an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which define rock feed-off points. The method may include arranging the plurality of rockfall barriers in rows with the rock feed-off points of all the rows being aligned with each other, so that ends of the plurality of rockfall barriers in a row open onto strike barriers in which the rocks may be arrested.

The method may include arranging the row of strike barriers along a contour of the constant incline mine slope, the strike barriers extending in a plane transversely upward from the slope. The strike barriers may be in the form of rockfall attenuators, arranged to be loose at the side proximate the slope with rockfall netting running over the constant incline slope, the rockfall netting having receiving ends proximate the strike barriers, in use receiving rocks underneath the netting and attenuating their movement down the slope.

The method may include aligning the rows of strike barriers underneath each other along the slope. The slope arrangement may thus define a rock flow path across the contours along the rockfall netting and underneath the strike barriers and rockfall netting.

In another embodiment, providing a plurality of rockfall barriers on at least one constant incline mine slope may include providing the plurality of rockfall barriers which extend in a plane transversely upward from the slope base and arranged at a slight incline relative to the contours of the constant incline mine slope. Each rockfall barrier may define an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which defines the rock feed-off points. The method may include arranging the rockfall barriers in rows with the rock feed-off points of one row of barriers being interspersed with apexes of the next lower row of rockfall barriers. In another embodiment, providing a plurality of rockfall barriers on at least one constant incline mine slope may include providing rockfall barriers in the form of rockfall netting sheets attached at their sides to the slope to define a rock flow path underneath the sheets along the mine slope.

The method may include arranging the sheets next to each other, being fixed to each other on their sides. In this method, the lower ends of the rockfall netting may define rock feed-off points, where rocks can collect and from where rocks can be removed.

In another embodiment, providing a plurality of rockfall barriers on at least one constant incline mine slope may include providing rockfall barriers in the form of rockfall attenuators comprising upright rockfall barriers of which the lower ends define rockfall netting drapes running over the slope. The rockfall barriers may be arranged along the contours of the slope with a plurality of rockfall barriers being provided on lower contours.

The end of the drape of the lowest rockfall barrier may define a rock feed-off point where rocks may collect on a specifically designed geotechnical catch bench or on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

The method may include constructing an open pit mine slope, which extends around all the pit slopes, including those slopes that do not contain ore. The method may include constructing the pit slopes with the slope base running at any one of a constant incline aligned with the ore body and at an average slope angle. The method may include constructing an open pit mine slope which extends around all the pit slopes, including those slopes that do not contain ore. The method may include constructing the pit slopes with the same average slope angle as the ore-bearing slope. The slope angle may be determined by the use of one or more of three slope design methodologies namely, Factor of Safety, Probability of Failure or Risk Consequence/Reward.

The invention extends to an open pit mine, which includes at least one open pit mine slope arrangement as described.

The invention will now be described by way of a non-limiting example only, with reference to the following drawing. DRAWINGS

In the drawings:

Figure 1 shows a sectional side view of an open pit mine slope arrangement in accordance with one aspect of the invention;

Figure 2 shows a schematic top view of another embodiment of an open pit mine slope arrangement in accordance with one aspect of the invention;

Figure 3 shows a schematic side view of strike barriers of the open pit mine slope arrangement of Figure 2;

Figure 4 shows a top view of another embodiment of an open pit mine slope arrangement in accordance with one aspect of the invention;

Figure 5 shows a sectional side view taken at V-V of the embodiment of the open pit mine slope of Figure 4;

Figure 6 shows a top view of another embodiment of an open pit mine slope arrangement in accordance with one aspect of the invention;

Figure 7 shows a sectional side view taken at VII-VII of the embodiment of the open pit mine slope of Figure 6;

Figure 8 shows a top view of another embodiment of an open pit mine slope arrangement in accordance with one aspect of the invention; Figure 9 shows a sectional side view taken at IX-IX of the embodiment of the open pit mine slope of Figure 8; and

Figure 10 shows a side view of a geotechnical catch bench, referred to in the specification.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

In Figure 1 a schematic sectional side view of an open pit mine slope arrangement 10 is shown. The mine slope is shown with the known batter and benches marked in broken line as reference numerals 12 and 14 respectively. These batters 12 and benches 14 are not implemented in the present invention, but are shown for illustrative purposes. The inclined slope 16 is aligned parallel or sub-parallel with the lower contact of the ore body 18. As can be seen mining the inclined slope progressively exposes ore 18 for mining. The ore is mined only to the slope level 16 and no batter 12 and benches 14 are constructed, leaving the slope level 16, which runs at a constant incline aligned parallel or sub-parallel with the lower contact of the ore body 18 or at the average or other slope angle determined by the use of one or more of the three slope design methodologies namely, Factor of Safety, Probability of Failure or Risk Consequence/Reward. As can be seen the waste material 22 remains intact leaving the material that would have to be removed to define the batters 12 and benches 14.

A plurality of rockfall barriers 24 (seen from the side) is parallel spaced at a slight incline relative to the contours of the slope 16.

In Figure 2, a schematic top view of an open pit mine slope arrangement 10 is shown. Three sets 26, 28, 30 of barriers 24 are shown with the barriers 24 arranged at a reflex angle to define apexes 26.1 , 28.1 , 30.1 with the barriers 24 at a slight angle across the contours (not shown). Ends of the plurality of rockfall barriers 24 define rock feed-off points.

Strike barriers, generally referred to by reference numerals 32 are provided below the ends of the rockfall barriers 24 to arrest rocks running down the rockfall barriers 24. In particular, the rock feed-off points open onto the strike barriers 32 in which the rocks are arrested.

As can be seen in Figure 3, the strike barriers in the form of rockfall attenuators 32, extend transversely from the slope 16. Rockfall netting 34 extends from the strike barriers 32 downwardly along the slope 16. The netting 34 defines a rock flow path 36 underneath the netting and the rock running downward in a controlled manner underneath the netting ending in a rock waste dump 38 at the end of the rock flow path or collected on a specifically designed geotechnical catch bench 100 (see Figure 10) or on the inside of a wide ramp 102 designed for purpose and from where the rocks may be removed. As can be seen in Figure 10 a rockfall barrier 104 is provided on the wide ramp 102. The constant incline mine slopes are indicated by reference numeral 106 with the pit floor as indicated as 108 and the slope crest as indicated by 1 10.

In Figures 4 and 5, another embodiment of an open pit mine slope arrangement 39 is shown. In this embodiment three rows 40, 42, 44 of catch fences 40.1 to 44.2 are arranged on a constant incline slope, each fence to define an apex and the three rows 40, 42, 44 being arranged in so that the apexes of the catch fences 40.1 to 44.2 are interspersed with the catch fences 40.1 to 44.2 of the adjoining rows 40, 42, 44.

In use, as can be seen in Figure 4, when a rock becomes dislodged it will move along the catch fences 44.2, 42.3 and 40.3 as indicated by arrows 46 to 50. In Figures 6 and 7, another embodiment of an open pit mine slope arrangement 60 is shown. In this embodiment, four bands 62, 64, 66, 68 of drape mesh are arranged and attached to a constant incline slope. The drape meshes are attached at the points generally marked with reference numeral 70.

In use, when a rock becomes dislodged it will progress underneath the drape mesh 62 to 68 along the constant incline slope to the bottom of the slope 72 from where it can be cleared.

In Figures 8 and 9, another embodiment of an open pit mine slope arrangement 80 are shown. In this embodiment, three bands 82, 84, 86 of rockfall attenuators are arranged parallel along the contours of a constant incline slope. The rockfall attenuators 82 to 86 are attached at the points generally marked with reference numeral 90. The rockfall attenuators 82 to 86, each defines an impact zone 82.1 to 86.1 and a tail drape 82.2 to 86.2. Although 3 parallel bands of rockfall attenuators are shown in Figures 8 & 9, any number of parallel bands of rockfall attenuators may be constructed, depending on the height of the inclined slope.

In use, when a rock becomes dislodged it will hit a rockfall attenuator 82, 84, 86 at the impact zone 82.1 , 84.1 , 86.1 and will then progress along the tail drape 82.2, 84.2, 86.2 along the constant incline slope to the bottom of the slope 88 or onto a specifically designed geotechnical catch bench or on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

The invention extends to a method of mining an open pit mine, which includes mining an ore body by removing the ore body and leaving a constant incline slope base as shown in Figure 1 , aligned with the bottom of the ore body or at the average or other slope angle determined by the useof one or more of the three slope design methodologies namely, Factor of Safety, Probability of Failure or Risk Consequence/Reward.

The method also includes providing a plurality of rockfall barriers arranged as shown in Figure 3 to 9.

It is to be appreciated that the new slope design can extend onto other mine pit slopes as well, including slopes that do not carry ore. The present invention defines a new open pit mine slope arrangement and a new method of mining an open pit mine, which will result in reduced mining of wastage material and the savings associated therewith.

Claims

CLAIMS:

1 . An open pit mine slope arrangement, which includes

at least one constant incline mine slope; and

2. An open pit mine slope arrangement as claimed in claim 1 , in which a slope base is aligned with a lower contact of an ore body, the slope base running at ant one of a constant incline aligned with the ore body and at an average slope angle.

3. An open pit mine slope arrangement as claimed in claim 1 , in which the plurality of rockfall barriers extend in a plane transversely upwardly from the slope base and arranged at a slight incline relative to the contours of the constant incline mine slope.

4. An open pit mine slope arrangement as claimed in claim 3, in which each rockfall barrier defines an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which defines rock feed-off points.

5. An open pit mine slope arrangement as claimed in claim 4, in which the plurality of rockfall barriers are arranged in rows with the rock feed-off points of all the rows being aligned with each other.

6. An open pit mine slope arrangement as claimed in claim 5, in which ends of the plurality of rockfall barriers in a row open onto a row of strike barriers in which the rocks are to be arrested.

7. An open pit mine slope arrangement as claimed in claim 6, in which the row of strike barriers are arranged along a contour of the constant incline mine slope, the strike barriers extending in a plane transversely upward from the slope.

8. An open pit mine slope arrangement as claimed in claim 7, in which the strike barriers are in the form of rockfall attenuators, arranged to be loose at the side proximate the slope with rockfall netting running over the constant incline slope, the rockfall netting having receiving ends proximate the strike barriers.

9. An open pit mine slope arrangement as claimed in claim 8, in which the rows of strike barriers are aligned underneath each other along the slope.

10. An open pit mine slope arrangement as claimed in claim 4, in which the rockfall barriers are arranged in rows with the rock feed-off points of one row of barriers being interspersed with apexes of the next lower row of rockfall barriers.

1 1 . An open pit mine slope arrangement as claimed in claim 1 , in which the rockfall barriers are in the form of rockfall netting sheets attached at their sides to the slope to define a rock flow path underneath the sheets downwards along the mine slope.

12. An open pit mine slope arrangement as claimed in claim 1 1 , in which the sheets are arranged next to each other, being fixed to each other on their sides.

13. An open pit mine slope arrangement as claimed in claim 12, in which the lower ends of the rockfall netting define rock feed-off points, where rocks can collect on any one of a specifically designed geotechnical catch bench and on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

14. An open pit mine slope arrangement as claimed in claim 1 , in which the rockfall barriers are in the form of rockfall attenuators comprising upright rockfall barriers of which the lower ends define rockfall netting drapes running over the slope.

15. An open pit mine slope arrangement as claimed in claim 14, in which the rockfall barriers are arranged along the contours of the slope with a plurality of rockfall barriers being provided down to the bottom of the pit.

16. An open pit mine slope arrangement as claimed in claim 15, in which the end of the drape of the lowest rockfall barrier defines a rock feed-off point where rocks are to collect on any one of a specifically designed geotechnical catch bench and on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

17. An open pit mine slope arrangement as claimed in any one of claims 1 to 16, in which the open pit mine slope arrangement extends around all the pit slopes, including those slopes that do not contain ore.

18. A method of mining an open pit mine, which includes

providing a plurality of rockfall barriers on at least one

constant incline mine slope.

19. A method as claimed in claim 18, in which removing the ore body includes leaving a slope base which is aligned with a lower contact of an ore body, the slope base running at any one of a constant incline aligned with the ore body and at an average slope angle.

20. A method as claimed in claim 18, in which providing a plurality of rockfall barriers on at least one constant incline mine slope includes providing rockfall barriers which extend in a plane transversely upwardly from the slope base and which barriers are arranged at a slight incline relative to the contours of the constant incline mine slope, each rockfall barrier defining an apex roughly midway of the barrier, the apex being at a slightly higher contour than the ends of the barrier, which define rock feed-off points.

21 . A method as claimed in claim 20, which includes arranging the plurality of rockfall barriers in rows with the rock feed-off points of all the rows being aligned with each other, so that ends of the plurality of rockfall barriers in a row open onto strike barriers in which the rocks may be arrested.

22. A method as claimed in claim 21 , which includes arranging the row of strike barriers along a contour of the constant incline mine slope, the strike barriers extending in a plane transversely upward from the slope.

23. A method as claimed in claim 22, in which the strike barriers are in the form of rockfall attenuators, arranged to be loose at the side proximate the slope with rockfall netting running over the constant incline slope, the rockfall netting having receiving ends proximate the strike barriers, in use receiving rocks underneath the netting and attenuating their movement down the slope.

24. A method as claimed in claim 23, which includes aligning the rows of strike barriers underneath each other along the slope.

25. A method as claimed in claim 20, which includes arranging the rockfall barriers in rows with the rock feed-off points of one row of barriers being interspersed with apexes of the next lower row of rockfall barriers.

26. A method as claimed in claim 18, in which providing a plurality of rockfall barriers on at least one constant incline mine slope includes providing rockfall barriers in the form of rockfall netting sheets attached at their sides to the slope to define a rock flow path underneath the sheets along the mine slope.

27. A method as claimed in claim 26, which includes arranging the sheets next to each other, being fixed to each other on their sides.

28. A method as claimed in claim 27, in which the lower ends of the rockfall netting defines rock feed-off points, where rocks can collect and from where rocks can be removed.

29. A method as claimed in claim 18, in which providing a plurality of rockfall barriers on at least one constant incline mine slope includes providing rockfall barriers in the form of rockfall attenuators comprising upright rockfall barriers of which the lower ends define rockfall netting drapes running over the slope.

30. A method as claimed in claim 29, in which the rockfall barriers are arranged along the contours of the slope with a plurality of rockfall barriers being provided on lower contours.

31 . A method as claimed in claim 30, in which the end of the drape of the lowest rockfall barrier defines a rock feed-off point where rocks are to be collected on any one of a specifically designed geotechnical catch bench and on the inside of a wide ramp designed for purpose and from where the rocks may be removed.

32. A method as claimed in claim 18, which includes

constructing an open pit mine slope, which extends around all the pit slopes, including those slopes that do not contain ore.

33. A method as claimed in claim 18, which includes constructing the pit slopes with the slope base running at any one of a constant incline aligned with the ore body and at an average slope angle.

34. An open pit mine, which includes at least one open pit slope arrangement as claimed in any one of claims 1 to 17.