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Questions and Answers
What is the primary environmental issue caused by Acid Mine Drainage (AMD)?
What is the primary environmental issue caused by Acid Mine Drainage (AMD)?
- Improvement of soil quality
- Leaching of heavy metals into water sources (correct)
- Enhancement of aquatic life growth
- Increase in biodiversity in aquatic ecosystems
Which of the following sulfide minerals is not mentioned in the context of Acid Mine Drainage?
Which of the following sulfide minerals is not mentioned in the context of Acid Mine Drainage?
- Pyrite
- Chalcopyrite
- Quartz (correct)
- Galena
What role do certain bacteria play in the process of Acid Mine Drainage?
What role do certain bacteria play in the process of Acid Mine Drainage?
- Bacteria neutralize the produced sulfuric acid
- Bacteria can catalyze the oxidation of sulfide minerals (correct)
- Bacteria clean up heavy metal contaminants
- Bacteria inhibit the oxidation process of sulfide minerals
Which of the following processes does not contribute to the generation of sulfuric acid in the oxidation of iron sulfide?
Which of the following processes does not contribute to the generation of sulfuric acid in the oxidation of iron sulfide?
What is a consequence of the acidic water produced by Acid Mine Drainage?
What is a consequence of the acidic water produced by Acid Mine Drainage?
Which environmental condition is primarily responsible for the oxidation of sulfide minerals leading to Acid Mine Drainage?
Which environmental condition is primarily responsible for the oxidation of sulfide minerals leading to Acid Mine Drainage?
What primary problem did the Summitville Mine face due to its mining process?
What primary problem did the Summitville Mine face due to its mining process?
What are the two main electron acceptors in the oxidation process of iron sulfide?
What are the two main electron acceptors in the oxidation process of iron sulfide?
Which method was employed at the Bjørndalen Mine to mitigate acid mine drainage?
Which method was employed at the Bjørndalen Mine to mitigate acid mine drainage?
What effect does the contamination from Acid Mine Drainage typically have on aquatic life?
What effect does the contamination from Acid Mine Drainage typically have on aquatic life?
What was the main purpose of the bioreactors used at Lily Mine?
What was the main purpose of the bioreactors used at Lily Mine?
What is a key characteristic of acid mine drainage that impacts ecosystems?
What is a key characteristic of acid mine drainage that impacts ecosystems?
Which bacteria type was specifically utilized in the Summitville Mine's bioreactor for AMD treatment?
Which bacteria type was specifically utilized in the Summitville Mine's bioreactor for AMD treatment?
What environmental issue did the Nelson Tunnel face as a result of historical mining activities?
What environmental issue did the Nelson Tunnel face as a result of historical mining activities?
What common outcome is associated with exposure of sulfide-bearing rocks in mining sites?
What common outcome is associated with exposure of sulfide-bearing rocks in mining sites?
What was the primary mineral extraction focus of the Wheal Jane Mine?
What was the primary mineral extraction focus of the Wheal Jane Mine?
What is the primary role of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the process of acid mine drainage?
What is the primary role of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the process of acid mine drainage?
What is a significant consequence of the positive feedback loop created by the oxidation of sulfide minerals?
What is a significant consequence of the positive feedback loop created by the oxidation of sulfide minerals?
Which of the following components is essential for the design of bioreactors used in AMD treatment?
Which of the following components is essential for the design of bioreactors used in AMD treatment?
What challenge is often faced when managing bioreactors for AMD treatment?
What challenge is often faced when managing bioreactors for AMD treatment?
What is a key limitation affecting the scalability of bioreactors for AMD treatment?
What is a key limitation affecting the scalability of bioreactors for AMD treatment?
What is formed when ferrous iron is oxidized in aerated streams due to the presence of oxygen?
What is formed when ferrous iron is oxidized in aerated streams due to the presence of oxygen?
Which of the following reactions contributes directly to the production of sulfuric acid in AMD?
Which of the following reactions contributes directly to the production of sulfuric acid in AMD?
What type of bacteria are primarily involved in the oxidation of iron sulfide in AMD?
What type of bacteria are primarily involved in the oxidation of iron sulfide in AMD?
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Study Notes
Acid Mine Drainage (AMD)
- Environmental problem caused by surface mining operations
- Leads to leaching of heavy metals into water sources
- Caused by bacterial and spontaneous oxidation of sulfide minerals
Sulfide Minerals
- Minerals containing sulfur as a major component
- Examples include pyrite (FeS₂), chalcopyrite (CuFeS₂), galena (PbS), sphalerite (ZnS), and molybdenite (MoS₂)
Oxidation of Iron Sulfide
- The oxidation of FeS₂ is a combination of chemically and bacterially catalyzed reactions
- Two electron acceptors participate in the process: O₂ & Fe³⁺
Bacterial Oxidation
- Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans are bacteria that play a crucial role in AMD
- These bacteria oxidize ferrous iron (Fe²⁺) to ferric iron (Fe³⁺)
- The ferric iron reacts with sulfide minerals, such as pyrite, to produce sulfuric acid (H₂SO₄)
- This process creates a positive feedback loop, where the increased acidity from sulfuric acid leads to further oxidation of sulfide minerals, accelerating AMD
Bioreactors
- Closed container with arrangements for aeration, agitation, temperature and pH control, and a drain or overflow vent to remove waste biomass of cultured microorganisms along with their products
Challenges of Using Bioreactors
- Careful management of environmental conditions is needed to ensure optimal microbial activity and metal recovery
- Fluctuations in pH, temperature, and nutrients can hinder efficiency
Limitations of Using Bioreactors
- Bioreactor scalability for AMD treatment is limited by factors like microbial interactions and site-specific needs
- This can hinder their widespread use in mining due to the need for customized designs
Case Studies of AMD
-
Wheal Jane Mine (England)
- Primarily known for gold and copper extraction
- Uses water treatment systems, mine reclamation, environmental rehabilitation, and monitoring
-
Summitville Mine (Colorado)
- Large-scale gold mine
- Mining process exposed sulfide minerals to oxygen, creating AMD
- Bioreactor using sulfate-reducing bacteria was introduced to treat the acid-laden waters contaminated with metals such as copper and zinc
-
Bjørndalen Mine (Norway)
- Historically used for mining various metals
- Waste rock and exposed ores contributed to AMD
- Passive bioreactors with organic materials were used to encourage sulfate-reducing bacteria to precipitate metals out of the AMD, neutralizing the water
-
Lily Mine (South Africa)
- Gold mine faced significant AMD issues
- Bioreactors using microbial processes were deployed to neutralize the AMD and remove heavy metals like iron and manganese from the water
-
Nelson Tunnel / Commodore Waste Rock Pile (Colorado)
- Part of a historic silver mining operation
- Exposed sulfide minerals led to severe AMD
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