mphephu frederick 2

REHABILITATION OF TAILINGS DAMS ON THE CENTRAL RAND,

JOHANNESBURGN F MPHEPHU

Centre for Applied Mining and Exploration Geology,School of Geosciences, University of the

Witwatersrand

Sudbury 2003: Mining and the EnvironmentSudbury, Canada, 25-28 May 2003

Acknowledgement:

• Prof. M.J. Viljoen (Supervision)

•Prof. H.J. Annegarn (Supervision)

•Ms. C. Davison (Water information)

Central Rand locality, geology and mining leases

Environmental impacts

Mine tailings status in 1961

Dust from mine dumps in early 60’s

Erosion of mine dumps in early 60’s

Early rehabilitation methods

Mulch spreading

Leaching

Re-vegetated dump

Rock-cladding

Water pollution

Pyrite in conglomerate

Conspicuous layers of dark largely unoxidized heavy minerals

Mine dump efflorescence

Layers of different oxidized heavy minerals showed by blueish and pinkish colour

Acid Mine Drainage close to the source

Tailings spillages to the wetlands

Riverleastream

Salts precipitation on bank stream-upper Klipspruit

Reclamation of Gold-bearing tailings dams

Tailings dams on the Central Rand

Gold-bearing silt-Fleurhof Dam

Monitoring method

Front-end loading method

Front-end loader

Re-exposure of reclaimed dump

Rand Leases dump close to Meadowlands

Rand Leases dump

Meadowlands

Moroeroe Primary School

Dust pollution during windy day- Meadowlands

New rehabilitation methods

Topsoil cover –Ergo dump

Liming

Use of slag to prevent dust

Active mine tailings of Central Witwatersrand

Poorly managed footprint

Efflorescence on tailings dams footprint

Acid mine drainage on tailings footprint

Oxidized heavy minerals on tailings footprint

Tailings footprints

Potential area for development-tailings footprints

Conclusion• Rehabilitation of mine tailings is

taking place in two ways:1. Revegetation method which suppresses

dust2. Reclamation of gold-bearing mine

tailings:§ removes pollution sources§ consolidate mine dumps into few sites§ open ground for development in prime

sites close to Johannesburg CBD