Adding Value. Delivering Results. WAIMM New Techniques & Innovations for Tailings Dam Construction and Operational Efficiency

Transcription

1 Adding Value. Delivering Results. WAIMM 2017 New Techniques & Innovations for Tailings Dam Construction and Operational Efficiency

2 Outline Industry Practices/Innovations What Technology, When/Where? Typical Plant and Operations Conclusions

3 Industry Practices/Innovations

4 Techniques and Innovations Tailings Storage Facilities Current Practices: Big tailings facilities with slurry discharge Some thickening prior to deposition Paste tailings/paste backfill Filtered Tailings By reducing the water sent to the tailings facility: Better geomechanical behavior (?) Reduced environmental impact (?) Reduced closure concerns (?) Costs (???) 4

5 Viscosity, Yield Stress, Cost Conventional Slurry Thickened Slurry Paste Filter Cake The Thickening Continuum 5-20 Pa 100 Pa Solids Content 800 Pa 5

6 The Thickening Continuum Increasing Solids Concentration Segregates on deposition Freely settled concentration No bleed water Non-segregating Soil behavior Conventional Tailings Thickened Tailings Paste Cake Ketchup 15 Pa Iron Ore Tailings, 64%m 100 Pa 6

7 Conventional to Thickened Slurry 7

8 Conventional to Thickened Slurry 8

9 Paste Tailings Paste Backfill 9

10 Filtered Tailings 10

11 What Technology, When/Where?

12 When to Consider Filtered Tailings? When the tailings are amenable to filtration When dam building material is scarce When operational controls can be assured When adequate compaction can be achieved (if necessary) When seasonal/climatic variations can be accommodated When maximum water recovery is needed (water supply/environment) When closure opportunities can be brought forward When maximum environmental protection is needed (?) 12

13 Amenable to Filtration Bench scale filtration testing equipment Cheap and easy 13

14 Amenable to Filtration Bench scale filtration testing equipment 14

15 Amenable to Filtration Bench scale filtration testing equipment 15

16 Amenable to Filtration 16

17 Building Material Availability Filtered Tailings Rock Rind Rock Starter Buttress Original Ground Surface 17

18 Operational Controls Important to have a good plan in place Early production growing pains What to do if tailings are wet Wet/dry season operational differences Consistency (or characterization) of ore body Overburden mining and geology Feed controls 18

19 Adequate (Necessary?) Compaction Production near OMC Compaction improves geotechnical performance Lower permeability Higher matric suction development Reduced risk of liquefaction Higher density = more storage Concerns: Moisture content at deposition Throughput Equipment availability 19

20 Seasonal/Climate Variations During wet season: Erosion can be problematic if not protected Run-off control is necessary More wet materials in center or up-hill During dry season: Dust control on surface and at transfer points Less wet materials toward outer shell better compaction 20

21 Maximum Water Recovery Majority of water is collected in plant Closed circuit water recovery Reduced evaporation from pond Potentially reduced seepage Less make-up water necessary (?) 21

22 Closure opportunities Low (or reduced) potential of ARD (and metals mobilizing) Keeping air out keeps the Fe from going ferric 22

23 Closure opportunities Adequately compacted and stable landform (if things went well) Ease of re-shaping for closure (if not completed during operation) Provides a possible walk-away closure solution Improved public buy-in (?) Improved permitting (?) 23

24 Typical Plant (Configuration) and Operations

25 Operations Process Belt/Drum/Vacuum Filters 25

26 Operations Process Plate and Frame 26

27 Operations Process Plate and Frame Closed/Squeeze Cake Conveyor Trap Door Open To Receive Cake 27

28 Transport and Placement 28

29 Transport and Placement 29

30 Transport and Placement 30

31 Transport and Placement Great opportunities for compaction Better geomechanical behavior Better storage efficiency Reduced construction costs (?) Waste becomes structural Water management benefits 31

32 Central America Similar Climate to Ghana 32

33 South America Arid Climate Poster Child 33

34 Conclusions

35 Conclusions As with all project developments, the technologies presented here should be considered as alternatives (there is no panacea or one size fits all ). Every project has its own right answer. Viability and advantages of filtered tailings should be evaluated on a project specific basis Climate, operational preferences, material characteristics, site layout, and economics should all be considered when evaluating tailings technologies, such as filtering 35

36 THANK YOU Name Phone Number