Fool's Gold and Acid Mine Drainage

Pyrite, often referred to as "fool's gold" due to its shiny, gold-like appearance, is a mineral composed of iron disulfide (FeS₂). While it is often mined for its iron content or as a byproduct of other mining operations, pyrite can also contribute to a significant environmental issue known as acid mine drainage (AMD).

How Pyrite Causes Acid Mine Drainage:

Oxidation of Pyrite: When pyrite is exposed to air and water, it undergoes an oxidation reaction. This process happens when oxygen from the air and water interact with the pyrite, producing sulfuric acid (H₂SO₄) and dissolved iron.

The reaction looks something like this:
4FeS2+15O2+14H2O→4Fe(OH)3+8H2SO44FeS_2 + 15O_2 + 14H_2O \rightarrow 4Fe(OH)_3 + 8H_2SO_4

The sulfuric acid produced is highly acidic, which can lower the pH of surrounding water bodies, creating harmful conditions for aquatic life and the surrounding environment.

Release of Heavy Metals: The oxidation process also releases heavy metals like arsenic, copper, lead, and zinc, which are often trapped in pyrite or the surrounding rock. These metals can become dissolved in the acidic water, further contaminating the environment and posing health risks to both wildlife and humans.

Formation of Acidic Water: As sulfuric acid dissolves in water, it lowers the pH, creating "acidic mine drainage." This acidic water is often orange, yellow, or red in color due to the presence of iron oxide (rust), and it can flow into nearby rivers, lakes, and groundwater.

Environmental Impact of Acid Mine Drainage:

Ecosystem Damage: The acidic conditions make it difficult for most aquatic life to survive. Species like fish, insects, and other organisms may not be able to tolerate the low pH or the presence of toxic metals.
Soil Contamination: The acid and dissolved metals can leach into the soil, affecting plant growth and potentially making agricultural land unusable.
Water Pollution: Acid mine drainage can pollute entire watersheds, making water sources unsafe for drinking, fishing, or recreational use.
Long-Term Persistence: Acid mine drainage can persist for decades or even centuries, long after mining operations have ended, due to the continued oxidation of pyrite and the release of acidic water.

Management and Mitigation:

Water Treatment: One way to address acid mine drainage is through water treatment systems that neutralize the acid, often by adding lime (calcium carbonate), which raises the pH. This is a temporary fix that can require constant maintenance.
Passive Treatment Systems: In some cases, passive systems like constructed wetlands or limestone channels can be used to naturally neutralize the acid and remove metals from the water.
Prevention through Best Practices: Proper waste rock management, sealing off pyrite-rich materials from exposure to oxygen and water, or even encapsulating pyrite with inert materials are methods used to prevent the generation of acid mine drainage at the source.

While pyrite itself is not inherently harmful in its natural state, its exposure to the elements during mining or other industrial activities can create lasting environmental challenges. Addressing acid mine drainage is a complex and ongoing issue, especially in regions with a long history of mining activities.

The Impact of Flooding on Acid-Forming Deposits

Flooding on the Bruce Highway between Bloomsbury and Proserpine. Flooding in this region is a constant feature of the wet season in the Whitsundays and surrounds.

Not a rare event

The Whitsundays Region and it's significant mountain regions, that feed from the Clarke Ranges into Dittmer’s floodplains make it particularly vulnerable to the spread of acid mine drainage.

When floodwaters move through mine tailings, waste rock dumps, or natural sulfide-rich deposits, several dangers emerge:

Contaminant Spread: Floods can carry acidic water and dissolved heavy metals into rivers, wetlands, and groundwater supplies.

Soil Degradation: Acidic water leaches into the floodplain soil, reducing fertility and affecting agricultural productivity.

Drinking Water Contamination: If acid-forming materials leach into groundwater, drinking water sources can become unsafe due to elevated metal concentrations.

Aquatic Ecosystem Damage: Low pH and high metal toxicity can kill fish, macroinvertebrates, and plant life, leading to long-term ecological damage.

Heavy Metal Mobilization and Toxicity

In addition to sulfuric acid, the oxidation of pyrite and other sulfide minerals releases toxic metals that are normally locked within the rock. In flood-prone regions like Dittmer, these metals pose a heightened risk:

Heavy Metal	Potential Health/Environmental Effects
Arsenic (As)	Carcinogenic, linked to skin, lung, and bladder diseases.
Lead (Pb)	Neurotoxin, particularly harmful to children, causing developmental issues.
Cadmium (Cd)	Causes kidney damage and bone disease.
Zinc (Zn)	Toxic to aquatic life at high concentrations.
Copper (Cu)	Can be toxic to fish and invertebrates in low pH waters.

Floods transport these metals into waterways, where they can accumulate in sediments and enter the food chain.

Risk of Mining Waste Being Exposed

Heavy rains and floods in Dittmer can:

Erode old tailings dams, exposing pyritic waste to oxidation.
Flush stored contaminants downstream, affecting areas that were previously unaffected.
Destabilise underground workings, leading to collapses or the sudden release of acid-laden water.

In a flood-prone area like Dittmer, pyrite-rich rock deposits and historic mining waste pose a significant environmental and health risk due to acid mine drainage and heavy metal contamination. Without proper containment and monitoring, flood events can spread these pollutants over a wide area, affecting water quality, soil fertility, and ecosystems.

Given the critical habitat designation of this area, is the establishment of a gold and copper mining operation, primarily benefiting a limited number of blue-collar workers and corporate executives - justifiable when weighed against the significant environmental risks?

We believe that the necessary environmental assessments are required before any approvals should be given to the applicants for this mining lease in such a critical region of environmental importance.