Your SlideShare is downloading. ×
Mine dewatering techniques
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Mine dewatering techniques

6,284
views

Published on

Mine dewatering techniques for open pit and underground mines

Mine dewatering techniques for open pit and underground mines

Published in: Technology, Business

1 Comment
5 Likes
Statistics
Notes
No Downloads
Views
Total Views
6,284
On Slideshare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
263
Comments
1
Likes
5
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. www.preene.com MINE DEWATERING Dr Martin Preene Preene Groundwater Consulting June 2014
  • 2. www.preene.com SYNOPSIS Synopsis • Water management for mining • Approaches to groundwater control • Examples of mine dewatering technology – Open pit – Underground – Shafts
  • 3. www.preene.com PRACTICE PROFILE Preene Groundwater Consulting is the Professional Practice of Dr Martin Preene and provides specialist advice and design services in the fields of dewatering, groundwater engineering and hydrogeology to clients worldwide Dr Martin Preene has more than 25 years’ experience on projects worldwide in the investigation, design, installation and operation of groundwater control and dewatering systems. He is widely published on dewatering and groundwater control and is the author of the UK industry guidance on dewatering (CIRIA Report C515 Groundwater Control Design and Practice) as well as a dewatering text book (Groundwater Lowering in Construction: A Practical Guide to Dewatering)
  • 4. www.preene.com MINE DEWATERING There are 3 aspects to the design and implementation of mine dewatering An understanding of: • Hydrogeology • Dewatering technology • Environmental sensitivities
  • 5. www.preene.com MINE DEWATERING There are 3 aspects to the design and implementation of mine dewatering An understanding of: • Hydrogeology • Dewatering technology • Environmental sensitivities
  • 6. www.preene.com RANGE OF APPLICATION OF METHODS From CIRIA Report C515 (2000): Groundwater Control: Design and Practice
  • 7. www.preene.com WATER MANAGEMENT FOR MINING Water Management Treatment if necessary PumpingExclusion Groundwater controlSurface water control Diversion Pumping Disposal to Waste Environmental Mitigation Beneficial use On site Off site
  • 8. www.preene.com WATER MANAGEMENT FOR MINING Water Management Treatment if necessary PumpingExclusion Groundwater controlSurface water control Diversion Pumping Disposal to Waste Environmental Mitigation Beneficial use On site Off site
  • 9. www.preene.com GROUNDWATER CONTROL Two main philosophies of groundwater control • Exclusion: Physical cut-off walls • Pumping: Arrays of wells or sumps (dewatering)
  • 10. www.preene.com EXCLUSION: VERTICAL CUT-OFF WALLS Cut-off walls penetrate into underlying low permeability stratum
  • 11. www.preene.com EXCLUSION TECHNIQUES • Displacement barriers – Steel sheet-piles • Excavated barriers – Concrete diaphragm walls – Bored pile walls (secant pile walls and contiguous pile walls) – Bentonite slurry walls and trenches • Injected barriers – Permeation grouting – Rock grouting – Jet grouting – Mix-in-place methods • Artificial ground freezing
  • 12. www.preene.com GROUNDWATER CONTROL BY PUMPING
  • 13. www.preene.com OPEN PIT METHODS In-pit pumping (sump pumping)
  • 14. www.preene.com OPEN PIT METHODS External deep wells Pumped by submersible pumps External wells behind pit walls
  • 15. www.preene.com OPEN PIT METHODS External deep wells and in-pit wells External wells behind pit walls In-pit wells
  • 16. www.preene.com OPEN PIT METHODS Horizontal drains to depressurise slopes
  • 17. www.preene.com OPEN PIT METHODS Cut off wall to exclude water in key strata Cut off wall
  • 18. www.preene.com OPEN PIT METHODS Wellpoint system to stabilise granular soils First stage wellpoints Second stage wellpoints
  • 19. www.preene.com OPEN PIT METHODS Drainage adits And tunnels Pumped drainage adit with drain holes
  • 20. www.preene.com UNDERGROUND METHODS • In underground mines, the conventional approach is to use the mine itself to control groundwater, by allowing the workings to act as drains • Once the water is in the mine it is passed along roadways (by pumping or gravity) to a deeper part of the mine (sump) or shaft bottom, to be pumped out via shaft or decline • Due to depth there may be a need for staged pumping to get the water out of the mine • In hard rock mines drain holes may be drilled out from workings • Important to minimise ‘dirty water’ (that has run along the floor/walls) and segregate ‘clean water’ (that has come straight from drain holes), because the water treatment requirements are different
  • 21. www.preene.com UNDERGROUND METHODS • Where fractured or water bearing zones are encountered, exclusion methods can be used to reduce water inflows. Grouting to seal inflow pathways is the most common approach • Grouting may be: – Planned or responsive – From surface (limited depth) or from workings (interferes with mining) • Most common type of grout is cementitious based grouts, but problems with grouting through flowing water and may be washed out before they set • Specialist chemical ‘water stopping’ polyurethane grouts are available to deal with flowing water but are expensive
  • 22. www.preene.com SHAFT SINKING METHODS • Deep shafts for mining present particular problems: – Depth – Limited space and complex working sequence – May pass through multiple aquifers • Common to use the exclusion approach – Cementitious grouting (cover grouting) – Artificial ground freezing • Rare to use external pumped wells apart from for shallow depths through granular soils • Even with exclusion methods there is a need to remove water from shaft bottom – Too deep to pump in one lift – Water often bailed out in hoisting kibble
  • 23. www.preene.com MINE DEWATERING Dr Martin Preene Preene Groundwater Consulting June 2014

×