Sustainable development and the environment Remediation.
-
Upload
garey-nash -
Category
Documents
-
view
221 -
download
1
Transcript of Sustainable development and the environment Remediation.
![Page 1: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/1.jpg)
Sustainable development and the environmentRemediation
![Page 2: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/2.jpg)
![Page 3: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/3.jpg)
Basic options
• Prevent/control – minewater generation– Migration of contaminated minewater
• Collect and treat contaminated water
![Page 4: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/4.jpg)
Controll at the site
• Prevent oxidation by eliminating– Processing rock containing reactive sulfide
• Use efficient extraction
– Segregate & isolate sulfide containing wastes– Exclude from oxygen and/or water– Control bacterial activity (if feasible, acceptable), temperature,
pH
![Page 5: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/5.jpg)
• Sulphide removal or isolation– One of the key objectives to waste management
planning!• What would be the other objective of WM?
![Page 6: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/6.jpg)
Exclusion of water
• Basal insulation• Prevention/reduction of infiltration by Dry
cover
– What are the conditions when basal insulation is needed/recommended for tailings?
![Page 7: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/7.jpg)
7BEST PRACTICE ENVIRONMENTAL MANAGEMENT IN MINING
Soil Covers
• Materials– Imported materials e.g. clay, soil– Low-sulphide waste rock, if
compactable– Geotextile fabrics– Covers may require zones
• Base (main sealing) layer - high water retention, low permeability
• Middle layer - water reservoir (may have higher permeability)
• Surface layer (barrier zone) - erosion protection and/or substrate for plant growth
the dry and water cover of waste areas as far as such is possible (dusting and/or seepage quality reduction and improvement of quality).
Materials can be from organic soil layer from the site (temporarily stored)Peat (if not erosion risk)
![Page 8: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/8.jpg)
8BEST PRACTICE ENVIRONMENTAL MANAGEMENT IN MINING
Isolation
Sulphidic waste
Top non-sulphidic waste layer
Basal layer
Revegetated and contoured cover material(surface capping and water storage medium)
Original ground surface
Freedumpednon-sulphidicwaste
Freedumpednon-sulphidicwaste
![Page 9: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/9.jpg)
• In principle similar• Alkalinisation by
limestone, lime, fly ash• Vegetation to
evapotranspirate water, erosion prevention– Metabolism introduces
dissolved CO2, (bicarbonate ions)
![Page 10: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/10.jpg)
Exclusion of oxygen
• Dry cover (soil cover) can aim also to prevent oxidation• Wet cover turned out effective way to reduce oxidation
– Diffusion rate of oxygen in water 1/10 000 times diffusion rate in air!
– Organic and certain inorganic reactions consume oxygen
Hammaslahti Zn mine
![Page 11: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/11.jpg)
• Water layer reduces diffusion of oxygen
• Reduced conditions developed as oxygen is consumed
• Sulfate become stable phase
• (Vegetation organic layers can promote SRB)
![Page 12: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/12.jpg)
Control of pH
• Increase of alkalinity– Reduces pH but is, in general
sufficient to induce precipitation of Cd, Zn, Ni and many other toxic metals
Enables other reactions and SRB
![Page 13: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/13.jpg)
Control of bacterial action
• Nearly neutral conditions
• a prerequisite for SRB
• Bacterisides have been applied to eliminate sulfite oxydicing bacteria– Effective until bactericides are
consumed• Difficult to sustain• ”emergency” action?
![Page 14: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/14.jpg)
Control of migration
• Controll of groundwater pollution by
• Reactive barrriers– Zero valent iron
• Extremely basic• U, Cr(IV), most metals
– Organic matter (suphate reaction)
• +SRB
• Continuos barriers
• Funnel and gate structures
![Page 15: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/15.jpg)
Collection and treatment
• Neutralization (pH control)
• Removal of metals
• Active treatment– Requires continuous operation
maintenance• Pump and treat etc.
– Passive systems• Intended to be self sustaining
after initial start-up
![Page 16: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/16.jpg)
Passive treatment
• Constructed wetlands
• Compositionally layers open pits (Hammaslahti mine)
• Successive alkalinity producing systems (SAPS)
• Limestone ditches/dams, open channels
![Page 17: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/17.jpg)
![Page 18: Sustainable development and the environment Remediation.](https://reader036.fdocuments.in/reader036/viewer/2022062409/5697bfae1a28abf838c9ccd4/html5/thumbnails/18.jpg)