EVALUATING THE LACK OF FLEXIBILITY AGAINST THE BENEFITS OF IN-PIT CRUSHING AND CONVEYING

Transcription

1 EVALUATING THE LACK OF FLEXIBILITY AGAINST THE BENEFITS OF IN-PIT CRUSHING AND CONVEYING Optimizing Mine Operations Conference Toronto 2013 Date Bob McCarthy Snowden

2 Outline Introduction IPCC basics Mine planning concepts for IPCC Guidelines for flexibility Conclusions

3 Introduction flexibility Flexibility is necessary? Just a matter of perspective Consider underground mining Fixed stope location and geometry Fixed development options Lack of flexibility bad? Consider underground mining technology Longwall coal mining Continuous miners and conveying Not too different from IPCC

4 Introduction paradigms Paradigm shift UG Miners are used to working under constraining conditions Open pit miners not so Requires a paradigm shift, but one with lateral familiarity How to survive the paradigm shift? Mine planning Change management

5 Introduction why bother? Potential rewards (study results) Cash cost reductions between US$0.18/t and US$0.82/t Net Present Cost improvements US$900m discount) Typical reduction in manning averages 6.5 persons per truck saved Typical reduction in ancillary equipment 25% Reduction in infrastructure costs (greenfields) Overall capital for long life mines is near neutral (when truck replacements are taken into account) Reduced carbon footprint

6 Introduction why bother? Truck savings

7 Outline Introduction IPCC basics Mine planning concepts for IPCC Guidelines for flexibility Conclusions

8 IPCC basics Integrated open-pit mining system A true alternative to pure truck-shovel operations Not a new technology Three general types of IPCC systems From MMD Group Fixed or Semi-fixed Semi-Mobile Fully Mobile

9 IPCC basics IPCC system components Crushers In-pit conveyors (fully mobile) Stationary conveyors Conveyor crossing Slewing spreader, radial stacker or tripper car spreader Ancillary equipment (crawlers, cranes, etc.)

10 IPCC basics fully mobile in-pit conveyors Bench transfer conveyor the conveyor that moves material from the mobile crusher to the bench conveyor It can come in many variations: belt wagons transfer bridges mobile conveyors per Sandvik Belt wagons and transfer bridges can convey to a bench conveyor above or below the current bench elevation per Metso

11 IPCC basics fully mobile in-pit conveyors Bench conveyor the conveyor that runs the length of a mining area (defined here as a panel), along which the mobile crusher traverses It can be fed from up to three benches (typical maximum) It is relocated by either track shifting (pipeline dozer) or selfpropelling Its length may change according to the width of the panel (but has minimum, driven by frequency of shifting) Bench conveyors on different benches Visonta lignite mine (Hungary) A.Oberrauner

12 IPCC basics fully mobile in-pit conveyors Portable conveyor a movable conveyor, used to extend the reach from or to a bench conveyor or dump conveyor of shorter length (up to 100 m), can be self-propelled may be used when erratic shaped benches are encountered or when dumps need extending can be used in series (piggy-back, grasshopper) per Terra Nova Technologies Ltd

13 Mining Direction Bench Trunk Conveyor IPCC basics fully mobile in-pit conveyors Bench trunk conveyor the conveyor to which the bench conveyor discharges is aligned in the overall mining direction (90 to the bench conveyor) needs to be extendable as mining advances Face Travel Bench Conveyor

14 IPCC basics stationary conveyors Stationary conveyor conveyors that are not regularly moved, but can be moved through dismantling and re-assembling modules Connection conveyor any non-specialised conveyor that transports material within the pit to a pit exit conveyor. Pit exit conveyor the last leg on the journey out of the pit, this typically ascends an incline, whether a pit haul ramp, a steeper dedicated conveyor ramp, or a tunnel incline; also used for ascending a waste dump Overland conveyor this conveyor connects the pit to the dumping area. This can be to a waste dump or an ore treatment facility per Sandvik

15 IPCC basics crossings Two common solutions to equipment / conveyor interactions Tunnel (culvert) Conveyor bridge

16 IPCC basics dumping / spreading systems Spreaders Radial stackers Tripper cars Track shiftable Self-propelled From Sandvik Mining and Construction

17 From FLSmidth IPCC basics dumping / spreading systems Discharge boom Transfer Bridge Tripper Car 50m >50m From Sandvik Mining and Construction

18 Outline Introduction IPCC basics Mine planning concepts for IPCC Guidelines for flexibility Conclusions

19 Mine planning Fully mobile panels and strips Semi-mobile crusher access Relocation of crushers Dump development

20 Mine planning fully mobile panels and strips Panels are serviced by a single bench conveyor on a single bench Multiple panels can operate in one pushback or terrace Panels are aligned in long dimension Panels are multiples of strips wide Bench conveyor can serve up to three benches in a panel

21 Mine planning fully mobile panels and strips When all benches in current strip are complete, bench conveyor track shifts When all strips in panel are complete, the system is relocated Relocation is either to another region of the pit of similar elevation or to a box cut to sink down

22 Mine planning fully mobile panels and strips Three bench operation (B3-C1-P1-N1) B Three benches per bench conveyor C One crusher per bench conveyor P One pass per strip N One bench conveyor per terrace

23 Mine planning semi-mobile crusher access Access options Permanent Temporary

24 Mine planning semi-mobile crusher access A permanent designed alcove into the high wall along the haul road access path Crusher Station Conveyor Access Ramp Slot Catch Berm Conveyor Bridge Down Ramp Direction Permanent Ramp System Up to Crusher Station & Waste Dumps Ramp Turning Area onto Crusher Tip Head Shovel

25 Mine planning semi-mobile crusher access A permanent location within an over-width haul road

26 Mine planning semi-mobile crusher access Taking advantage of a temporary wall for a permanent station location

27 Mine planning semi-mobile crusher access A temporary location along the haul road with access to the truck tip off the haul road Conveyor Bridge Ramp Conveyor Crusher Station Operating Shovel Operating Shovel

28 Mine planning semi-mobile crusher access A temporary location along the haul road with access to the truck tip via temporary ramps off the bench TurningArea.. No Access to Exit Pit Ramp Shovel Face CrusherStation TEMPORARYRamp Shovel Face

29 Mine planning semi-mobile crusher access For each additional bench, the length of a temporary ramp (and footprint on the working bench) increases. Each additional bench increases the average cycle time for the trucks and therefore the number of trucks needed. Balancing this is the desire to reduce the frequency of crusher shifts. Beyond four benches per crusher shift, the footprint of the temporary access ramp becomes significant relative to the available bench area. While a crusher could be relocated once every 6 months, no more than once per year is preferable; therefore, 4 benches per year is a good maximum bench advance rate.

30 Mine planning relocation of crushers Common misconception that relocation takes months and is a major engineering task Crusher relocation can be accomplished in 7 days or less From Sandvik Mining and Construction

31 Mine planning relocation of crushers From Sandvik Mining and Construction

32 Mine planning conveyor pit exits Primary challenge is the pit exit corridor Options include: Alongside haul roads Dedicated conveyor routes (can be greater than 20%) Tunnel Most common route is the haulage ramp Complex exits increase the number of transfer points

33 Mine planning haul road considerations Extra width required for conveyor allocation

34 Mine planning dedicated conveyor pit exit Truck Turning Circle Area Dedicated Conveyor Ramp at 15 degree angle Double Crusher Station Temp 10% Road Ramp for Truck Access to Dump Pocket Area Crusher Station Relocation Access Area

35 Mine planning dedicated conveyor pit exit Using what geology gave you

36 Mine planning flexibility? you bet Conveyor distribution point, Hambach lignite mine, Germany per RWE

37 Mine planning IPCC dump designs Generic simplified radial dump layout

38 Mine planning IPCC dump designs Can be very high dump heights

39 Mine planning IPCC dump designs Waste dumping starting bottom-up dump

40 Mine planning IPCC dump designs IPCC dumps differ from truck waste dumps per: The location of the dump does not need to be immediately adjacent to the pit. With spreaders, there is no dump lift height restriction due to the risk of crest failure as a spreader can stand far back from the dump edge. Geotechnical investigation is still required of foundation, but also resized waste material. Leachates?

41 Outline Introduction IPCC basics Mine planning concepts for IPCC Guidelines for flexibility Conclusions

42 Guidelines to IPCC mine planning Key considerations in planning for all IPCC systems Material characteristics determination (UCS, fines, abrasiveness) Loading equipment matching to IPCC Operating hours of overall system Mining above IPCC ramp conveyors is generally not allowed; blasting adjacent to IPCC equipment to be reduced or eliminated Maximize size of push backs for: vertical bench advance, elbow room, pit exit conveyor on haul road Pit exit conveyors use footwalls or temporary walls to advantage; establish lowest accessible depth SMIPCC vs FMIPCC Dump construction generally not an issue unless construction is bottom up in which case consider truck built starter platforms or if no trucks, a viable sequence. Electricity supply; is it there?

43 Guidelines to IPCC mine planning Key considerations in planning for Semi-Mobile IPCC Elaborateness of crusher stations; <240t trucks vs. ultra class Blast design; multiple bench and pre-split blasting for crusher stations Crusher relocation planning; temporary ramps vs permanent ramps Vertical advance rate is constrained; though 8 benches per year are technically possible, 4 or less are preferred to reduce crusher relocations Ensure truck dump traffic flow allows for achieving expected crusher feed rates

44 Guidelines to IPCC mine planning Key considerations in planning Fully Mobile IPCC Minimum strip/bench conveyor length; balance maximizing IPCC usage vs. conveyor shifting and relocation delays Maximize IPCC mineable material by appropriate panel/strip configurations Multiple bench configurations; maximize benches served by a single bench conveyor datum (three bench operation optimal) Plan out box cut sequence, schedule accordingly; consider extra bench conveyor to minimize delays Plan out dump construction, particularly if bottom up and no trucks available

45 Outline Introduction IPCC basics Mine planning concepts for IPCC Guidelines for flexibility Conclusions

46 Conclusions IPCC means a whole new terminology and way to approach mine planning Cost savings and other benefits are substantial, while loss of flexibility is real There is no replacement for good planning to create a mine plan that builds in flexibility that is lost operationally IPCC is a new paradigm and transitioning to it is a significant change Ensure change management aspects are addressed, if not a full change management approach