High

1. High Highwall Mining - Design Tradeoffs – Economic Impacts Mine Expo 2012 Bradley Charles Lewis -- ADDCAR Systems

2. Three Methods of Highwall Mining • Advantages of Highwall Mining • Risks • Engineering Design • Operational Design • Trade - Offs • Equipment Options • Crew • Capital and Operating Costs • KPI’s • Future Highwall Mining A hybrid of surface and underground mining technologies extracting reserves that would have otherwise been left behind

3. Surface Mine at its Economic Limit FINAL WALL

4. Surface Mine at its Economic Limit FINAL WALL

5. Intermittent Occurrence • Plenty of Working Room • Minimal Interference from Existing Operation • Postpones Reclamation • Abundant Highwall • Wider pits • In Pit Stockpiling FINAL WALL

6. Rolling Terrain – Marginal Ratios Trench Mining

7. Rolling Terrain – Marginal Ratios Trench Mining End View Mine Both Directions

8. Rolling Terrain – Marginal Ratios Trench Mining

9. Double Highwall • Multiple Trenches strategically located increases reserve recovery • Backfill the back end with front end material that is being removed to advance the trench • (+/- 1,200 ft. haul distance) • Reduced surface disturbance Trench Mining

10. Mountainous Terrain – High Ratio Ringing the Mountain

11. Mountainous Terrain – High Ratio Ringing the Mountain

12. nnnnnnnn • Extreme congestion • Often times multiple seams • High ratios result in narrow benches • Precise orchestration of daily activities mandatory • Most difficult to keep ahead on available highwall • Often times the area has been previously mined Ringing the Mountain Plan View HWM Entries

13. Advantages of Highwall Mining • People Free Underground Mining method – all employees are on the surface because the equipment is operated remotely • Reduced environmental footprint – coal can be removed by underground mining methods and not impact the surface overlying the area being mined • Highest Productivity / Lowest costs  - this method of mining does not require roof bolts, rock dust, overburden removal, etc • Increased reserve recovery - allows mining of reserves which would have otherwise been abandoned

14. Highwall Mining Risks • Pinch Points • Highwall • Equipment Congestion • Methane • Mitigate risks by designing them out, guarding ,labeling , training

15. Engineering Design • Web Pillars -an appropriate width which allows the HWM entries to be self supporting for a predetermined time period • Barrier Pillars - an appropriate width to prevent a domino collapse from overriding into the active mining area • Highwall Profile – blend of wall, bench & layback angle resulting in stability

16. Red Fonts are Mine Specific Variables

17. Operational Design • Keeping Wall Available –most difficult aspect of highwall mining • Equipment Layout – mine toward stored conveyors & away from coal pile. All pieces have an optimum location in each pit • Repeatable Process – study the process constantly and tweak continuously for improved performance

18. Operational Design – Multi Seam Top Down Generate income while mining down Ground control problems typically propagate upwards into the mined out area Always seated on rock Can visually inspect the columnized entries

19. Operational Design – Multi Seam Top Down Pillar failure below the active working can weaken the overall highwall Less risk of equipment entrapment due to an underlying failure Subsidence impacts the mined out / overlying area and does not sterilize the coal below

20. Operational Design – Multi Seam Bottom Up Less risk to personnel No need to coordinate with surface mining operation Backfill provides confinement to any failures No air blast risk from the openings

21. Operational Design – Multi Seam Bottom Up Mined out highwall which may be unstable is below you No stress concentrations from overlying mined out areas Stand up time has to be longer which means wider pillars

22. Trade – Offs

23. Trade – Offs

24. Lowe Trade – Offs

25. E Equipment Options A D D C A R

26. E Equipment Options A D D C A R

27. Equipment Options C A T Equipment Options

28. B R Y D E T

29. ADDCAR’s Advantagesover the Competition Inertial Navigation System Gamma Sensor Controls Product Size Depth of Mining Capability Conveyor Car System

30. Ke Skills Ranking Electrical Electronics Hydraulic Print Reading Hand Eye Coordination Ability to be away from home for extended periods Can Do Attitude Teamwork Multi – Tasker Problems Solver Crew Makeup Miner Operator - 1 General Labor - 2 End Loader Op - 1 Mechanic - 1 Electrician - 1 Foreman - 1 Total 7

31. Capital & Operating Cost are greatly impacted by mine specific conditions & customer preferences. Actual costs are determined by assessing: Reserves Geologic Conditions Mine Plans Regulatory Environment Markets Financial Standing Ke Ball Park Numbers Capital Cost US $ 10 Million Operating Cost $10.00 / ROM Ton Monthly Output 75,0000 tons

32. Key Performance Indicators • Reportable Accident Frequency • Feet Mined / Shift • Actual / Planned Hole Depth - % • System Uptime - % • (based on a 24 hour clock)

33. Backfilling entries with fly ash and then mining the pillar between the back filled entries • Incorporating the guidance technologies to existing continuous miner operations • Adapting the HWM system / method for underground use to maximize reserve recovery Future Possibilities

34. FfF The future of underground mining is Surface Mining Future Possibilities Fully Autonomous