Full Scale Flow Marker Experiments at the Ridgeway Deeps and Cadia East Block Cave Operations

Transcription

1 Full Scale Flow Marker Experiments at the Ridgeway Deeps and Cadia East Block Cave Operations Ian Brunton (Itasca Australia) James Lett (Newcrest Mining Limited) Glenn Sharrock (Itasca Australia) Tim Thornhill (Newcrest Mining Limited) Ben Mobilio (Newcrest Mining Limited

2 Cadia Valley Operations Located approximately 250 km west of Sydney, 20 km south of Orange, NSW. Ridgeway SLC and Ridgeway Deeps For the year ending June 2015, 667,418 ounces of gold and 73,697 tonnes of copper were produced at CVO. Over 8 million ounces of gold has been produced from CVO since commercial production commenced in Cadia Hill Cadia East 500 m 2000 ft

3 Experimental Objectives The experiments aimed at quantifying and assessing: the development and shape of the extraction zone potential flow mechanisms controlling flow behaviour identify possible sources of waste ingress ascertain the degree of flow behaviour variability

4 Definitions and Conventional Flow Theory isolated movement movement zone zone draw cone extraction zone isolated extraction zone A. Conceptual Ellipsoid Flow Model (modified after Janelid and Kvapil, 1966) B. Small Scale Bunker Model Displaying Ellipsoid Movement Zone (after Kvapil, 1965)

5 Disturbed Flow A. Large interlocking mass of particles (magenta) acts to disturb the flow of the fully dilated zone (red arrows) B. Small scale physical model showing flow disturbance around a large particle

6 Experimental Design Considerations The design of the experimental program was based upon a number of criteria related to the: experimental objectives marker density both laterally and vertically budget constraints drill availability and capability underground development and access existing location of open holes (exploration and hydrofracture) undercutting schedule geological variability expected cave geometry

7 Flow Markers - Metal a) Metal marker (after Power, 2004) b) Installation of marker in up hole (after Power, 2004) c) Installation of marker in deep down hole

8 Flow Markers - Electronic Installation Readers are installed above locations where the LHDs, extracting ore and electronic markers, will travel. Electronic Markers activated and installed in the cave (drill holes, development). Extraction After installation, electronic markers flow with the broken caved material to the drawpoint. LHD loads caved material and electronic markers into bucket. Detection Readers mounted on to the the tipple crosscut back back (and detect potentially electronic other markers locations in the in LHD the future) detect bucket. electronic Reader data markers is transferred in LHD to the bucket. Surface Reader via network data is or transferred Bluetooth to download. the surface via network or Bluetooth download.

9 Ridgeway Deeps Experimental Design 5100 SLC Level Deep hole markers (5040 and 5070 levels) 5040 SLC Level 5070 SLC Level 5010 SLC Level Open hole markers Sublevel cave markers (5010 level) Eastern cave boundary undercut markers (4804 XN22) Central region undercut markers (XN3, 5, 7 & 9) Electronic marker trial area (4804 XN27) 4804 Undercut Level 4786 Extraction Level

10 Ridgeway Deeps Experimental Design 4804 Undercut Marker Rings 19.5 m UR /5070 Deep Hole Markers

11 Cadia East PC1 Experimental Design 5050 Hydrofracture Level 5050 Level Markers Deep Hole Markers Undercut Level Markers 4670 Undercut Level 4650 Extraction Level

12 Cadia East PC1 Experimental Design 4670 Undercut Marker Rings 5050 Deep Hole Markers

13 Fragmentation Distribution RWD 10,000 t RWD 30,000 t CEPC1 10,000 t CEPC1 30,000 t

14 70 m (near field) 32 m 65 m Ridgeway Deeps Marker Recovery 4905 R.L. 26 % Markers Recovered 37 % Markers Recovered 4840 R.L. 25 % Markers Recovered 52 % Markers Recovered 61 % Markers Recovered 4786 Extraction Level A. Installed Markers B. Marker Recovery December 2010 (Average Drawpoint Tonnes 14,520 t) C. Marker Recovery June 2012 (Average Drawpoint Tonnes 50,850 t) D. Marker Recovery June 2014 (Average Drawpoint Tonnes 114,460 t)

15 70 m (near field) 40 m 55 m 4770 R.L. Cadia East PC1 Marker Recovery Note: Marker detectors commissioned 17 July At this stage approximately 22,000 tonnes extracted from 108W07 and 0 tonnes extracted from 110E07. 8 % Markers Recovered 24 % Markers Recovered 4715 R.L. 14 % Markers Recovered 20 % Markers Recovered 28 % Markers Recovered 4650 Extraction Level 110E07 = t 108W07 = t 110E07 = t 108W07 = t 110E07 = t 108W07 = t A. Installed Markers B. Marker Recovery November 2013 C. Marker Recovery August 2014 D. Marker Recovery August 2015

16 5050 R.L. Cadia East PC1 Marker Recovery 70 m (near field) 330 m (far field) 130 m 200 m 4850 R.L R.L Extraction Level 0.3 % Markers Recovered 110E07 = t 108W07 = t 3 % Markers Recovered 110E07 = t 108W07 = t 11 % Markers Recovered 110E07 = t 108W07 = t A. Installed Markers B. Marker Recovery August 2014 C. Marker Recovery February 2015 D. Marker Recovery August 2015

17 Cadia East PC1 Marker Recovery Data Point Density (5 m Square Counting Grid) Undercut Level Extraction Level

18 Conclusions Marker experiments at the RWD and CEPC1 block cave operations provide insight into the development of the extraction zone during undercutting and subsequent draw. With respect to the two block cave operations, marker recovery in both the near and far fields have indicated disturbed flow behaviour (marker recovery is not spatially uniform during material extraction). In the region above the major apex, recovery was noted to occur for all heights. For the two operations, the sequence in which near field markers were recovered varied: For RWD (advanced undercut), early material recovery was close to the major apex, and expanded towards the centre of the draw bell as more material was extracted. The inverse was observed for CEPC1 (post undercut), where recovery occurred in the centre of the drawbell initially, and expanded outwards towards the major apex. This trend of recovery for the two operations continued in the far field.

19 Conclusions For the CEPC1 marker experiment, electronic markers were utilised to investigate the vector movement of material in the near field. Marker recovery movement vectors in the near field indicated that the extraction zone width was in the order of 30 m, with localised marker recovery outside this region (significant horizontal movement of material potentially due to cave muckpile rilling and blast burden movement). Analysis is ongoing for far field marker vector movement.

20 Acknowledgements The authors wish to thank Newcrest Mining Limited (NML) for the support and permission to publish this paper. The initiation and implementation of these projects would not have been possible without the assistance of David Finn, Geoff Dunstan, Jack Dermody, Stephen Duffield, Geoff Capes, Michelle Morgan, Robert Lowther, Luca Popa, and Joseph Emmi, and Corey McKenzie.