Planning best practice tailings disposal, management and rehabilitation strategies Presented by Mike Gowan
Dec 11, 2015
Planning best practice tailings disposal, management and rehabilitation strategies
Presented by
Mike Gowan
2Tailings – Brisbane 28/02/06
The Simple Early Mining Life
3Tailings – Brisbane 28/02/06
Before TSFs – Sand Dumps
4Tailings – Brisbane 28/02/06
The Simple Life – Cocopan Haulage
5Tailings – Brisbane 28/02/06
Before Tailings Pumping Systems
6Tailings – Brisbane 28/02/06
Early TSF Construction
7Tailings – Brisbane 28/02/06
TAILINGS STORAGE FACILITIES
Named a TSF Includes:
Storage walls and footprintSlurry pipelinesReturn water damReturn water system
But they do not always “store” the tailings
8Tailings – Brisbane 28/02/06
Kalgoorlie before Kaltails
Wind and Water Erosion
9Tailings – Brisbane 28/02/06
TSFs
Largest dams ever built – seen from space
Unlike water dams, have to last “for ever”
Normally built progressively over a long period – up to 50 years
Often built with non-engineering materials
Should be considered as a living entity
10Tailings – Brisbane 28/02/06
20 Years On using Tailings!
Upstream raised gold TSF
11Tailings – Brisbane 28/02/06
Mining Realities
Mining a continuous operation TSF at the back end of the operation
Generally “out of sight and out of mind” A cash consumer, not a cash contributor A source of “constipation” when they go
wrong
Do it right the first time!!!
12Tailings – Brisbane 28/02/06
TSF Failures
At least 2 TSF failures reported annually
Many more not reportedFailure includes:
Wall failureWall breachOvertoppingRelease of contaminated liquor Contaminated seepage
13Tailings – Brisbane 28/02/06
Unreported Wall Failure
Out of Sight
14Tailings – Brisbane 28/02/06
Unreported TSF Failure
No Injuries
15Tailings – Brisbane 28/02/06
Unreported Contaminated Flow
“Contained”
16Tailings – Brisbane 28/02/06
In-River Tailings Disposal
In river
17Tailings – Brisbane 28/02/06
Result of Failures?
Poor public perceptionOmaiBaie MareMarcopperLos Frailes
Leads to a lack of trust
18Tailings – Brisbane 28/02/06
Failures
No TSF failures are unexpectedAll failures can be predicted with
hindsightFailures due to one or more of:
Poor designPoor construction managementPoor operationChanging management during
operationLack of rigorous and regular
inspection
19Tailings – Brisbane 28/02/06
OUR DUTY AS DESIGNERS
Carry out a rigorous design Provide the owner with clear
operating guidelines Stand-up for our role Record, assess and advise
20Tailings – Brisbane 28/02/06
Appropriate Tailings Disposal
Design must:Meet project requirementsSatisfy legislative standardsFollow current engineering
knowledgeLook to better environmental
expectations
21Tailings – Brisbane 28/02/06
Transportation
Low solids content slurryHigh solids slurryPasteCakeDry
22Tailings – Brisbane 28/02/06
Ash - 12% Solids
23Tailings – Brisbane 28/02/06
Diamonds - 45% Solids
24Tailings – Brisbane 28/02/06
Gold - 70% Solids
25Tailings – Brisbane 28/02/06
Tailings Placement
PumpingLow solids contentHigh solids content
ConveyingTrucking or railing
26Tailings – Brisbane 28/02/06
Conventional
2 Stage Pumping for Codisposal
27Tailings – Brisbane 28/02/06
Paste
1 MW Diaphragm Positive Displacement Pump - Flyash
28Tailings – Brisbane 28/02/06
Conveying
Flyash
DryFlyash
DewateredTailings
29Tailings – Brisbane 28/02/06
Trucking
Flyash
30Tailings – Brisbane 28/02/06
Why Change?
The drier the tailings the lower:Water losses Chemical lossesRisks of environmental contamination Rehabilitation costs
Increased risk of:DustErosion
31Tailings – Brisbane 28/02/06
Dust & Erosion
Dust
Erosion
32Tailings – Brisbane 28/02/06
Understand the Tailings
SeepageWater qualityDustRadiation InstabilityGeomorphological processes
33Tailings – Brisbane 28/02/06
Seepage in a Dry Environment
HDPE Liner to reduce Seepage
34Tailings – Brisbane 28/02/06
Radiation
Subaqueous to reduce Radiation
35Tailings – Brisbane 28/02/06
Accidents do Happen!!
The Human Element
36Tailings – Brisbane 28/02/06
Mine Expansion
Two mining realities:The full tonnage is achieved well
ahead of scheduleMore ore is found
SO:Plan for full tonnage earlierConsider expansion
• Do not limit expansion through design
• Consider the next TSF site
37Tailings – Brisbane 28/02/06
Conclusion
Endeavour to place tailings back in mine
Legislated in California
Plan for tailings retreatmentProvide comprehensive
Operational Management Documentation
38Tailings – Brisbane 28/02/06
Coal Tailings In Final Void
39Tailings – Brisbane 28/02/06
Paste Backfilling Underground
Paste Backfill
40Tailings – Brisbane 28/02/06
In-Pit Codisposal - Gold
Tailings Waste
41Tailings – Brisbane 28/02/06
The EndMy thanks to:
Fraser Alexander for old photos
Mining clients for use of project photos
Various authors quoted without reference
My colleagues who keep me on my toes!!??