AU2009208123A1

AU2009208123A1 - Mining system

Info

Publication number: AU2009208123A1
Application number: AU2009208123A
Authority: AU
Inventors: Collette Amos; Ernest Georg Griebel
Original assignee: Technological Resources Pty Ltd
Current assignee: Technological Resources Pty Ltd
Priority date: 2008-08-11
Filing date: 2009-08-11
Publication date: 2010-02-25

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant (s) TECHNOLOGICAL RESOURCES PTY. LIMITED Invention Title: Mining System The following statement is a full description of this invention, including the best method for performing it known to me/us: - 2 Mining System The present invention relates to open pit mining of ore that contains valuable metals. 5 The present invention relates particularly, although by no means exclusively to mining of iron ore. Conventional open pit mining of iron ore comprises 10 progressively drilling and blasting sections of an ore body so that the ore can be picked up by shovels or other suitable excavators and transported from a pit on haulage trucks. It is known to mine iron ore in large blocks using a series of benches so that various mining 15 activities can be carried out concurrently in a pit. A bench, which may be for example 40-200 m long by 20-100 m deep by 10-15 m high and containing many thousands of tonnes of ore and/or other material, is first drilled to form a pattern of "blast" holes. The material removed 20 during the course of drilling the blast holes is analysed, for example by chemical analysis, to determine whether, on average, the ore is (a) high grade, (b) low grade or (c) waste material. The cut-off between high and low grades is dependent on a range of factors and may vary from mine 25 to mine and in different sections of mines. The bench of ore is blasted using explosives, typically ANFO (ammonium nitrate/fuel oil) based, that are dispensed in specially designed bulk dispensing trucks which can regulate the explosive density prior to loading down the blast holes. 30 The blasted material is picked up by earth moving vehicles in the form of excavators such as electric rope shovels, diesel hydraulic excavators, or front end loaders and placed into haulage vehicles such as trucks and transported from the mine pit. The ore is processed 35 outside the mine pit depending on the grade determination. For example, waste ore is used as mine fill, low grade ore is stockpiled or used to blend with high grade ore, and -3 high grade ore is processed further as required to form a marketable product. Because conventional open pit mining uses blasting, 5 care must be taken in drilling and blasting in the vicinity of proposed walls of the mine to minimise blast induced damage. The slopes of the walls must take account of such damage and cable bolting is often employed to provide additional slope stability. The slope of the wall 10 of a mine may be staggered in a series of steps know as "berm". Some of these berms are wide enough to provide for a haulage road to be established passing up the wall of the mine. Typically such haulage roads progressive wind their way up the wall in a series of switch backs. 15 The time taken for haulage of blasted ore increases with the depth of the pit. The present invention is an alternative mining method to the above-described method. 20 The mining method of the present invention may be used as the only method of mining in a mine pit or as one of several mining methods in a mine pit. 25 According to the present invention there is provided a method of mining ore in a mine pit that comprises the steps of: (a) mining ore from a floor of a mine pit and/or 30 collecting ore on a pit floor using at least one mobile excavation machine in the form of a continuous surface miner; (b) transporting mined and/or collected ore from the 35 mobile excavation machine within the mine pit to at least one ladder conveyor that extends up the wall of the pit; and - 4 (c) transporting ore to outside the pit on the ladder conveyor. 5 The method may comprise transferring ore that has been transported along the ladder conveyor onto at least one main conveyor and transporting the ore to a processing plant and/or a load-out station. 10 The term "continuous surface miner" is understood herein to mean any machine that is capable of moving over a pit floor and mining ore from the pit floor or collecting mined ore on the pit floor. It is noted that the pit floor is unlikely to be a flat surface and 15 typically will be an uneven surface with loose rocks on the floor. The continuous surface miner may comprise, by way of example, a drum that carries a plurality of cutting 20 elements, such as cutter picks, and is rotatable about a horizontal axis and cuts into and thereby mines material that forms a pit floor as the surface miner advances across the pit floor. The mobile excavation machine may be any other type of continuous surface miner. 25 The continuous surface miner may excavate ore to a depth in a range of 300-600 mm and at a rate of at least 900 tph (more typically at least 1200 tph) and travel at a speed of at least 5 m/min (more typically at least 10 30 m/min). Step (b) of the method may comprise forming a stockpile of mined and/or collected ore from ore that has been mined and/or collected by the mobile excavation 35 machine in the mine pit and transporting ore from the stockpile to the ladder conveyor.

- 5 The ore may be transported from the stockpile to the ladder conveyor on a haulage truck. Step (b) may comprise transferring ore from the 5 stockpile to the truck via a mobile feed system, for example in the form of a feed hopper. Another, although not the only other possible, option for step (b) of the method is to transport mined and/or 10 collected ore from the mobile excavation machine on a haulage truck to the ladder conveyor. Step (b) may comprise transporting ore to the ladder conveyor on at least one mobile trunk conveyor that 15 extends along a section of the pit floor to the ladder conveyor. The term "mobile trunk conveyor" is understood herein to mean conveyors that persons in the mining industry 20 refer to as "shiftable" or "movable" conveyors. A "shiftable" or "movable" conveyor is a conveyor that can be repositioned in a mine after a period of mining has been completed. In other words, the conveyor is not mobile in the sense that it can move continuously, for 25 example, to keep pace with a mobile excavation machine or other mobile machine while continuing to operate to transport mined and/or collected ore along the conveyor. The conveyor is mobile in the sense that it can be shifted or moved periodically to a new location. 30 The trunk conveyor may comprise at least one ore loading station and step (b) may comprise off-loading ore from the haulage truck onto the ladder conveyor at the loading station and transporting ore on the trunk conveyor 35 to the ladder conveyor.

- 6 The trunk conveyor may be located on the pit floor in a lower region of the pit. The main conveyor may be located generally on a rim 5 of the pit or at a base of a local topography surrounding the pit and follow the topography thereof. The main conveyor may receive ore from more than one part of the pit or from a series of pits. 10 The term "ladder conveyor" as used herein is understood to mean a conveyor that is able to transport ore from a mine pit directly up a wall of the mine pit from the pit floor. 15 The wall of the mine pit may be a steep wall, i.e. at least 200, more typically at least 30*, in many instances at least 65* to the horizontal. 20 The pit wall may be at least 20 m and typically at least 40 m high. The ladder conveyor may be a single conveyor from the pit floor to the rim of the mine pit and extends up the 25 pit wall without transfer points along the length of the conveyor, i.e. without the ore being off-loaded at an upper end of one section of the conveyor and loaded onto a lower end of a successive section of the conveyor. 30 The ladder conveyor may extend up the pit wall without a switchback. The ladder conveyor may comprise a belt that at least substantially encloses ore being conveyed on the conveyor. 35 The method may comprise extending the ladder conveyor in response to a general lowering of the pit floor.

According to the present invention there is also provided a mine that comprises at least one pit having a pit floor and a pit wall that defines at least a part of the pit, at least one mobile excavation machine in the 5 form of a continuous surface miner for mining ore from the pit floor and/or collecting ore on the pit floor, transport means for transporting mined and/or collected ore within the mine pit, and at least one ladder conveyor for transporting mined and/or collected ore from the pit. 10 The mine may comprise a main conveyor outside the pit for transporting mined and/or collected ore from the pit to a processing plant or a load-out station. 15 The mine may comprise a plurality of pits and at least one main conveyor outside the pits for transporting mined and/or collected ore from the pits to a processing plant or a load-out station. 20 The pit wall may be a steep wall, i.e. at least 20*, more typically at least 30*, in many instances at least 650 to the horizontal. The pit wall may be at least 20 m and typically at 25 least 40 m high. The ladder conveyor may be a single conveyor from the pit floor to the rim of the mine pit and extends up the pit wall without transfer points along the length of the 30 conveyor, i.e. without the ore being off-loaded at an upper end of one section of the conveyor and loaded onto a lower end of a successive section of the conveyor. The ladder conveyor may extend up the pit wall 35 without a switchback.

- 8 The mine may comprise at least one stockpile of mined and/or collected ore from the mobile excavation machine in the mine pit. 5 The transport means may comprise at least one haulage truck for transporting mined and/or collected ore within the mine pit The ore may be transported from the stockpile to the 10 ladder conveyor on trucks. The mine may comprise at least one mobile trunk conveyor that extends along a section of the pit floor to the ladder conveyor. 15 The trunk conveyor comprise at least one ore loading station for receiving ore from a haulage truck The pit floor may be at a plurality of different 20 levels. By way of example, the mine may be an iron ore mine. The present invention is now described by way of 25 example only with reference to the accompanying Figure which is a schematic diagram of a layout of a mine pit that illustrates one embodiment of a method of mining iron ore in accordance with the present invention. 30 The following description is in the context of mining iron ore. It is understood that the present invention is not limited to mining iron ore and extends to mining other ores. 35 It is also understood that the mine layout shown in the Figure is schematic and is intended to represent a mine layout in a very general sense.

- 9 With reference to the Figure, a mine pit generally identified by the numeral 3 and having a pit floor 5 is defined at least in part by mine walls 7. The mine walls 5 7 are shown as opposed straight walls for convenience only and the present invention is not limited to this arrangement. The pit floor 5 may be at one level. Alternatively, the pit floor 5 may be on multiple levels, i.e. multiple benches, which may be isolated from each 10 other or interconnected by ramps (not shown). The method of the present invention makes it possible for the angle of inclination of each mine wall 7 from the pit floor to be relatively steep, thereby minimising the 15 loss of mined area. Typically, the angle of inclination is at least 20*. In many situations the angle may be at least 450*. Each mine wall 7 may comprise a series of steps or be one continuous wall. The method of the present invention makes it possible to form the mine walls 20 7 as steeper walls than is currently the case and, where steps are required, the steps need not be as wide as is currently the case. More particularly, the method of the present invention makes it possible to form the mine walls 7 without the use of cable bolting or other mechanical 25 means to provide additional slope stability. A plurality of mobile excavation machines in the form of surface miners 11 mine ore from the pit floor 5. It is noted that the pit floor 5 is unlikely to be a flat 30 surface and typically it will be uneven with loose rocks on the floor. By way of example, the surface miners 11 may comprise a drum that carries a plurality of cutter picks and is rotatable about a horizontal axis and cuts into and thereby mines material that forms the pit floor 35 as the surface miner advances across the pit floor. Typically, the surface miner can mine ore to a depth in a - 10 range of 300-600 mm at a rate of at least 900 tph and can travel at a speed of at least 5 m/min. The surface miners 11 make it possible to mine ore 5 directly from the pit floor 5 and avoid the need to drill and blast a mine at least in certain sections of the mine pit 3. The surface miners 11 (and other equipment) may be 10 controlled remotely or by operators on the miners. In either case, typically the paths of movement of the surface miners 11 (and other equipment) within the mine pit 3 are in accordance with a mining plan. The paths of movement include, by way of example, a surface miner 11 15 advancing in one direction for a predetermined distance and mining ore from the pit floor, turning around and advancing in the opposite direction for the predetermined distance and mining ore from the pit floor, and repeating this pattern of movement to mine ore from a section of the 20 pit floor. One group of the surface miners 11 shown in the Figure transfers mined ore outwardly from the surface miners 11 as the miners 11 advance and forms piles in the 25 form of windrows 21 within the mine pit 3. The ore in the windrows is transferred via mobile feed systems 43 onto trucks 13 and the trucks transport the ore to a trunk conveyor 27 or a ladder conveyor 23, both of which are described hereinafter. 30 The mobile feed systems 43 may be hoppers. Alternatively, or in addition, the mobile feed systems 23 may be in the form of crushers to produce at least some size reduction of the ore. 35 Whilst the windrow 21 is shown as a straight windrow, the present invention is not confined to this arrangement - 11 and the form of the windrow or pile may be determined as required given the topography of the mine. Another group of the surface miners 11 transfers 5 mined ore from the surface miners 11 to trucks 13 and the trucks transport the ore to the above-mentioned trunk conveyor 27 or ladder conveyor 23. More specifically, the ore is transported via the 10 trucks 13 across the pit floor 5 either (a) directly to the ladder conveyor 23 that is arranged to transport the ore from the mine 3 directly up the mine wall 7 or (b) to the internal trunk conveyor 27, i.e. a "shiftable" or "movable" conveyor, that extends along the pit floor 5 15 adjacent the wall 7 and transports the ore to the ladder conveyor 23. The trunk conveyor 27 may have a series of transfer stations 37 for receiving ore from the trucks and feeding 20 ore onto the trunk conveyor 27. The ladder conveyor 23 may be in a fixed location against the wall 7 or may be mounted for movement along the length of the wall 7. In the latter case, the trunk 25 conveyor 27 is arranged to be shiftable or movable or other wise able to be extended to accommodate the change in location of the ladder conveyor 23. In both cases, the ladder conveyor 23 may be extendable in length as the pit depth increases. 30 The ladder conveyor 23 transports the ore via a transfer point 61 onto a conveyor assembly 29 that extends along the rim of the mine pit 3 and interconnects a series of pits and/or different sections of the same pit and 35 transports the ore to a processing plant, such as a crusher, or to a load-out station.

- 12 The conveyor assembly 29 may be of a type that facilitates separation of ore into two process streams, with one stream, such as a high grade ore, being transported for processing in a crusher, and the other 5 stream, such as waste ore, being transported to a stockpile for subsequent use as a fill material. It is relevant to note that the arrangement shown in the Figure represents a section of a pit only and the 10 mining method illustrated with reference to the Figure is repeated in other sections of the pit 3. It may also be the case that other mining methods are used in different sections of the pit 3. In any event, the mined ore is transported from the mine via ladder conveyors 23 and is 15 delivered to the conveyor assembly 29. The ladder conveyor 23 may be any suitable conveyor. By way of example, the ladder conveyor 23 may be of the type manufactured by International Conveying Systems 20 International and described in Australian patent 767395 in the name of Michael Pietsch. The mobile trunk conveyor 27 may be of any suitable type. By way of example, the mobile trunk conveyor may be 25 as manufactured by International Conveying Systems International and described in Australian patent 767395, but operated in a static mode. Many modifications may be made to the method of the 30 present invention summarised in the Figures and described above without departing from the spirit and scope of the present invention. By way of example, whilst the Figure shows surface 35 miners 11 transferring mined ore outwardly from the surface miners 11 as the miners 11 advance and forming windrows 21 within the mine pit 3, the present invention - 13 is not so limited and the mined ore could be feed downwardly from the miners 11 and form windrows behind the miners 11. 5 By way of example, whilst the Figure shows one ladder conveyor 23, the present invention is not so limited and extends to arrangements in which there is a plurality of ladder conveyors in a pit. 10 By way of example, whilst the Figure shows a pit floor that has one level only, the present invention is not so limited and extends to mines in which the pit floor has a plurality of levels.

Claims

1. Amethod of mining ore in a mine pit that comprises the steps of: 5 (a) mining ore from a floor of a mine pit and/or collecting ore on a pit floor using at least one mobile excavation machine in the form of a continuous surface miner; 10 (b) transporting mined and/or collected ore from the mobile excavation machine within the mine pit to at least one ladder conveyor that extends up the wall of the pit; and 15 (c) transporting ore to outside the pit on the ladder conveyor.

2. The method defined in claim 1 comprises transferring 20 ore that has been transported along the ladder conveyor onto at least one main conveyor and transporting the ore to a processing plant and/or a load-out station.

3. The method defined in claim 1 or claim 2 wherein the 25 mobile excavation machine is a continuous surface miner.

4. The method defined in claim 3 wherein the continuous surface miner excavates ore to a depth in a range of 300 600 mm and at a rate of at least 900 tph (more typically 30 at least 1200 tph) and travels at a speed of at least 5 m/min (more typically at least 10 m/min).

5. The method defined in any one of the preceding claims wherein step (b) comprises forming a stockpile of mined 35 and/or collected ore from ore that has been mined and/or collected by the mobile excavation machine in the mine pit - 15 and transporting ore from the stockpile to the ladder conveyor.

6. The method defined in claim 5 comprises transporting 5 ore from the stockpile to the ladder conveyor on at least one haulage truck.

7. The method defined in claims 6 wherein step (b) comprises transferring ore from the stockpile to the 10 haulage truck via a mobile feed system, for example in the form of a feed hopper.

8. The method defined in any one of claims 1 to 5 wherein step (b) comprises transporting mined and/or 15 collected ore from the mobile excavation machine on at least one haulage truck to the ladder conveyor.

9. The method defined in any one of claims 1 to 5 wherein step (b) comprises transporting ore to the ladder 20 conveyor on at least one mobile trunk conveyor that extends along a section of the pit floor to the ladder conveyor.

10. The method defined in claim 9 wherein the trunk 25 conveyor comprises at least one ore loading station and step (b) comprises off-loading ore from the haulage truck onto the ladder conveyor at the loading station and transporting the ore on the trunk conveyor to the ladder conveyor. 30

11. A mine that comprises at least one pit having a pit floor and a pit wall that defines at least a part of the pit, at least one mobile excavation machine in the form of a continuous surface miner for mining ore from the pit 35 floor and/or collecting ore on the pit floor, transport means for transporting mined and/or collected ore within - 16 the mine pit, and at least one ladder conveyor for transporting mined and/or collected ore from the pit.

12 The mine defined in claim 11 comprises a main 5 conveyor outside the pit for transporting mined and/or collected ore from the pit to a processing plant or a load-out station.

13. The mine defined in claim 11 or claim 12 comprises a 10 plurality of pits and at least one main conveyor outside the pits for transporting mined and/or collected ore from the pits to a processing plant or a load-out station.

14. The mine defined in any one of claims 11 to 13 15 wherein the pit wall is a steep wall, i.e. at least 200, to the horizontal.

15. The mine defined in any one of claims 11 to 14 wherein the pit wall is at least 20 m and typically at 20 least 40 m high.

16. The mine defined in any one of claims 11 to 15 wherein the ladder conveyor is a single conveyor from the pit floor to a rim of the mine pit and extends up the pit 25 wall without transfer points along the length of the conveyor, i.e. without the ore being off-loaded at an upper end of one section of the conveyor and loaded onto a lower end of a successive section of the conveyor. 30

17. The mine defined in any one of claims 11 to 16 comprises at least one stockpile of mined and/or collected ore from the mobile excavation machine in the mine pit.

18. The mine defined in any one of claims 11 to 16 35 wherein the transport means comprise at least one haulage truck for transporting mined and/or collected ore within the mine pit - 17

19. The mine defined in any one of claims 11 to 18 comprises at least one mobile trunk conveyor that extends along a section of the pit floor to the ladder conveyor. 5

20. The mine defined in claim 9 wherein the trunk conveyor comprises at least one ore loading station for receiving ore from a haulage truck.