Acid Mine Drainage Concepts

A small change in pH value represents a significant change in the concentration of H+ ions.

Substances that resist changes in pH by absorbing excess H+ ions.

The ability of a solution to resist changes in pH.

Acidic soil is common in areas with high rainfall and poor buffering capacity.

Alkaline soils are common in areas with low rainfall and high mineral content.

Rainfall can lower the pH of soil over time, making it more acidic.

The chemical process where pyrite reacts with oxygen and water, producing hydrogen ions (H+) and contributing to acid mine drainage.

A mineral composed of iron sulfide (FeS2) with a characteristic brassy yellow color.

The chemical compound formed during pyrite oxidation, often found as a yellow-orange precipitate.

Acidic water runoff from mines, often caused by the oxidation of pyrite in the surrounding rocks.

A type of bacteria that accelerates the oxidation of pyrite, greatly increasing the production of acid mine drainage.

The process of extracting gold using cyanide, often used in mining operations.

A major cyanide spill that occurred in Romania, highlighting the risks associated with gold mining.

A strategy to reduce or eliminate acid mine drainage by preventing the contact of pyrite with oxygen and water.

A measure of the acidity or alkalinity of a solution. It is logarithmic, meaning a small change in pH represents a large change in hydrogen ion concentration.

Rainwater naturally combines with carbon dioxide in the atmosphere to form carbonic acid, which makes it slightly acidic. This results in a pH range of 5.6 to 5.7 for clean rainwater.

Typically found in environments with heavy rainfall and decomposing organic matter, such as rainforests and jungles.

Often found in drier regions with low rainfall, such as deserts, where weathering processes lead to the accumulation of alkaline minerals.

The natural pH range for most plants is acidic, typically between 5.5 and 7.

The weathering of sulfide minerals like pyrite occurs in the presence of oxygen and water. When these minerals are submerged underwater, they are sheltered from oxygen, significantly slowing down the weathering process.

A visible manifestation of geological weathering processes. It is characterized by reddish or yellowish hues caused by the presence of iron oxide compounds, commonly formed through the oxidation of sulfide minerals.

Silica is a material used in inorganic coatings and is valued for its stability, acid resistance, and longevity.

Acid mine drainage happens when sulphides in exposed rocks react with air and water.

Acid mine drainage can contaminate nearby water sources like streams, rivers, lakes, and groundwater.

Acid mine drainage negatively affects the physical, chemical, and biological aspects of aquatic environments.

Gold is soft and malleable, meaning it can be hammered into thin sheets or drawn into thin wires.

Gold is often found combined with other metals, like silver.

Cyanide is used in gold processing to extract gold by dissolving it from other metals and leaching it into the surrounding water.

Impurities remaining after the melting process are called slag.

The natural pH range for most plants is slightly acidic, ranging from 5.5 to 7.

Sulfide minerals like pyrite, when submerged in water, will not weather significantly due to the lack of oxygen. Oxygen is essential for the oxidation reaction that leads to weathering.

Gossan is a rusty-colored rock, often found at the surface, formed by the weathering of sulfide minerals like pyrite.

Acid Mine Drainage (AMD) is the acidic water draining from mines, often contaminated with heavy metals, caused by the oxidation of sulfide minerals.

Some treatments for Acid Mine Drainage (AMD) include adding buffers like limestone to neutralize acidity, limiting exposed rock, compacting acid-generating rock, and covering the rock with sealing layers.

Dry cover methods involve creating a layer of material over the sulfide-bearing waste to prevent oxidation and AMD. These methods usually include a layer of plastic liners.

Wet cover methods for AMD prevention involve completely submerging the sulfide-bearing waste in water to prevent oxidation, but require high maintenance costs.

While various AMD treatments are used to delay or prevent oxidation, they all have limitations. Physical barriers like wet or dry covers offer short-term effectiveness, while bactericides are toxic and only work on fresh tailings. Chemical barriers are effective but expensive.

A chemical compound used in gold mining that can be highly toxic to aquatic life and humans.

The minimum concentration of a substance that is lethal to 50% of the exposed population.

The ability of a substance to break down naturally in the environment.

The inability for cells to use oxygen effectively, often caused by cyanide poisoning.

The process by which a substance is absorbed through the eyes or skin.

The chemical breakdown of a compound by reacting with oxygen, often producing acidic byproducts.