In metal mines, valuable ores like gold, silver, and copper are often found within sulphide minerals. When these sulphides are exposed to air and water during mining operations, a chemical reaction generates sulfuric acid. This acid can then dissolve and release toxic metals and metalloids, such as arsenic, from the surrounding rock, leading to a dangerous environmental issue known as acid mine drainage (AMD).

Understanding Acid Mine Drainage

Acid mine drainage (AMD) can occur wherever sulphide minerals are exposed, including waste rock piles, tailings (the residue from ore processing), open pits, underground tunnels, and leach pads. A common sign of acid drainage is “yellow boy,” a yellow-orange precipitate that forms when the pH of acidic water rises above 3, causing dissolved iron to solidify and settle. Streams affected by AMD often have dangerously low pH levels—sometimes as low as 4 or lower—making them as acidic as battery acid. These highly acidic conditions severely damage aquatic life, plants, and wildlife dependent on these ecosystems.

A notable example is the Zortman Landusky mine in Montana, where acid and metal runoff has devastated biological life in numerous streams across the Little Rocky Mountains. The long-lasting nature of acid mine drainage makes it particularly destructive—it can continue to occur long after mining activities have ceased. A comprehensive literature review on the subject has noted that no hard rock surface mines have been able to demonstrate the successful cessation of acid mine drainage once it has begun on a large scale. This enduring environmental threat underscores the necessity of stringent laws and regulations to manage and mitigate the impacts of mining operations.

To address this ongoing threat, it is essential that mining operations are held to the highest environmental standards. Preventing AMD requires thorough planning and management of waste rock, tailings, and other mine by-products, along with effective water treatment systems to neutralise acid before it causes lasting damage.

Minetek’s Role in Mitigating Acid Mine Drainage Through Advanced Evaporation Systems

Minetek’s advanced wastewater evaporation solutions play a vital role in the mining industry’s efforts to address the severe environmental challenges of acid mine drainage (AMD). As a global leader in industrial water management, Minetek Water brings decades of expertise in providing sustainable and efficient solutions to some of the most complex environmental issues, making them a trusted partner for organisations aiming to achieve safe, compliant, and profitable operations.

Minetek's land-based evaporation systems are highly effective at managing various water qualities, making them particularly valuable for mitigating risks associated with sulphidic mine waste and other toxic leachates. These systems are not only the largest and most cost-effective globally but are also designed with mobility and flexibility in mind, allowing for deployment in even the most demanding industrial environments. This adaptability enables mine operators to concentrate on their core operations—such as production and profitability—while ensuring strict environmental compliance.

The technology behind Minetek’s water evaporators is based on fundamental principles of fan engineering and airflow dynamics, resulting in an efficient and sustainable solution. These evaporators are capable of handling water with pH levels ranging from 2.2 to 12, covering both highly acidic and caustic conditions, as well as water with elevated levels of total dissolved solids (TDS) and total suspended solids (TSS). This versatility is crucial for addressing the complex water management challenges posed by AMD, where water chemistry can vary widely.

One of the key features of Minetek’s evaporators is their ability to evaporate up to 50% of the sprayed water volume as pure water vapour, depending on the climate, with the remaining droplets returning to the feed pond. This high level of efficiency not only reduces the volume of hazardous water that requires treatment but also helps to minimise the environmental footprint of mining operations. The evaporators are equipped with patented nozzles capable of handling solids up to 4.0mm in diameter, ensuring long-term durability and reliable performance even in challenging conditions.

With a proven track record of over 700 successful projects worldwide, Minetek has solidified its position as a leader in water evaporation technology. Their land-based evaporators are particularly renowned for consistently processing various types of contaminated water, helping to safeguard ecosystems from the ongoing threat of acid mine drainage. Minetek’s dedication to innovation and environmental stewardship is clear in its approach, which balances operational efficiency with a strong commitment to ecological responsibility.

Conclusion

AMD remains a significant environmental challenge, with the potential to cause lasting harm to ecosystems long after mining activities have ceased. Addressing this issue requires stringent regulations, careful management of mining by-products, and the implementation of advanced technologies.

Minetek’s innovative wastewater evaporation solutions provide an effective and sustainable approach to mitigating the risks associated with AMD. By offering flexible, efficient, and environmentally responsible water management systems, Minetek is playing a crucial role in helping the mining industry meet its environmental obligations while maintaining operational profitability.

For more information on our water management solutions, click the link below to download our eBook on our Minetek Water Evaporation Technology.

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L'importance de la réhabilitation progressive dans l'industrie minière australienne

In recent years, the Australian mining industry has made notable progress in meeting social and environmental responsibilities, particularly through the growing emphasis on progressive rehabilitation plans at active mine sites. This shift reflects a positive change, integrating environmental restoration as a continuous part of mining operations rather than a final step.

These sustainable practices represent a sharp contrast to historical mining approaches, which often left behind a legacy of abandoned, environmentally compromised sites. Australia now hosts approximately 80,000 inactive mines, many dating back to the gold rush era of the 1850s—a period of rapid economic growth that helped build cities like Melbourne but left a lasting environmental impact.

Without regulations for mine rehabilitation at the time, many sites were deserted after resource extraction, resulting in persistent environmental issues today. These abandoned mines contribute to dust pollution, soil erosion, and waterway contamination from heavy metals and other pollutants, underscoring the critical importance of current sustainable practices in the industry.

The enduring impact of abandoned mines underscores the critical need for ongoing rehabilitation. In regions impacted by historical mining, state governments continue to address the environmental legacies left behind, undertaking complex and costly remediation projects. These efforts often involve removing toxic materials, stabilising mine tailings, and restoring natural habitats.

Proactive rehabilitation is essential—not only for addressing immediate environmental risks but also for supporting the long-term ecological health of areas surrounding mining sites. The industry’s commitment to reducing its environmental footprint is evident in the mandate for progressive rehabilitation practices at all active mine sites, ensuring responsible land use and sustainability.

Water Management Challenges in Mine Closure

Water-related issues are among the most severe environmental impacts following mine closures, with effects that can persist for decades or even centuries. When mines cease operations, a lack of ongoing management can lead to the build-up and release of contaminated water, posing significant risks to nearby ecosystems and communities. A major concern is acid mine drainage (AMD), a reaction where sulphide minerals in exposed rock surfaces interact with air and water to produce sulphuric acid. This acid then leaches heavy metals from the surrounding rock, creating a toxic mix that can pollute nearby rivers, lakes, and groundwater.

An example highlighting these issues is a 2017 study by Dr. Ian Wright, a prominent Australian water scientist. His research on the Berrima Colliery, an abandoned coal mine in New South Wales under ‘care and maintenance’ since 2013, revealed that the site was releasing roughly 30 litres of heavy metal-laden water per second into the Wingecarribee River—equivalent to an Olympic-sized pool of toxic water discharged each day. This study underscores the ongoing challenges posed by water contamination at closed mine sites.

The water discharged from the Berrima Colliery contains dangerously high concentrations of heavy metals, including zinc, nickel, and manganese—elements known to harm human health and aquatic ecosystems. For example, zinc levels are more than 120 times the normal baseline, posing a serious threat to the river’s ecological balance. These contaminants degrade water quality and accumulate in the river’s sediment and organisms, leading to lasting ecological damage.

The impact of this contamination goes well beyond the immediate environment. As part of Sydney’s drinking water catchment, the Wingecarribee River could affect the health of millions relying on it as a water source. Local fishing communities are also concerned, as heavy metals bioaccumulate in the food chain, affecting fish populations essential for nutrition and livelihood. Contaminated fish present direct health risks to consumers who may unknowingly ingest toxic substances.

This case highlights the potential long-term impact of mining on water resources, underscoring the need for robust water management and treatment in mine closure plans. Without such measures, abandoned mines could continue to threaten public health, ecosystems, and local economies for generations.

Minetek’s Comprehensive Water Management Strategies

The Risks of Transporting Polluted Water

Many clients worry about water evaporation. They often say their water quality is too poor for effective evaporation. Instead, they think someone must take it off-site. This perception overlooks several critical considerations.

Firstly, transporting contaminated water off-site poses significant environmental and logistical challenges. Hazardous liquids, like those with heavy metals and acids from mining, can spill or leak during transport. These incidents can result in severe environmental contamination along transportation routes, affecting soil, water sources, and ecosystems.

In contrast, treating and evaporating water on-site reduces the need for transportation. This lowers the risks of spills and leaks. This approach improves overall environmental safety and mitigates liabilities for mining companies.

On-site evaporation is a flexible solution. It can handle water of different qualities. This includes highly contaminated water that may seem hard to treat at first. Minetek offers advanced evaporation technologies that effectively manage diverse types of contaminated water.

These systems can manage high levels of pollutants, such as heavy metals and acidic compounds. They work by evaporating water and concentrating the contaminants for later disposal or recycling. This ability helps the environment by lowering the overall impact of mining. It also makes sure that water management meets regulatory standards.

Minetek’s Advanced Evaporation Technology

Minetek has pioneered advanced evaporation technology designed to address the diverse challenges of wastewater management in mining and industrial settings. Built on foundational principles of fan engineering and airflow, our patented systems ensure efficient, cost-effective, and sustainable evaporation of wastewater.

This technology is designed to manage various water qualities. It works with water that is very acidic or very alkaline, with a pH range of 1.8 to over 14. It can also process water with solid particles up to 4.0mm in size.

Our mobile and flexible solutions have worked well in more than 700 projects across 29 countries. This includes countries and regions such as Brazil, Central and West Africa, the Caribbean, Southeast Asia, and the Southeastern USA. Minetek earns global recognition for delivering environmentally sustainable water management outcomes, enabling mining operations to prioritise production and profitability while meeting stringent environmental standards. This track record of success is a testament to the versatility and reliability of our evaporation technology.

Minetek’s mechanical evaporators work by pumping water at high pressure. The water goes through special nozzles that break it into fine droplets. These droplets are released into the air to evaporate. This process separates water from contaminants like solids, salts, and heavy metals.

Our evaporation technology treats the water directly. This is different from traditional water treatment methods. Those methods focus on the substances found in the water. This means it is mostly unaffected by the specific contaminants present. This unique approach ensures that the concentration and separation of pollutants occur outside the evaporator, minimising the environmental impact of wastewater disposal.

The Advantages & Capabilities of Minetek’s Evaporation Technology

There are a number of other benefits mining companies can expect from adopting our evaporation technology.

• Wide Range of Volume Capacity: Minetek has systems that can operate over 2,160 m3/hour. This shows they can scale to meet different water management needs.
• Low Maintenance Units: Designed for efficiency and reliability, Minetek’s evaporation units require minimal maintenance, reducing operational downtime.
• 24/7 Automated Operation: These systems operate continuously with automated controls, ensuring round-the-clock functionality.
• Low-Fouling, High-Pressure Atomising Stainless Steel Nozzles: These units use specialised nozzles that minimise fouling and effectively atomise water for efficient evaporation.
• Minetek technology can process water with high levels of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS). This ensures strong performance with different types of water.
• Quick Deployment: Teams can easily set up and adjust these systems. They have modular and mobile designs to fit specific site needs.
• Minimal Footprint & Power Required: Designed for efficiency, these systems occupy minimal space and consume less power than traditional methods.
• Land-Based, Floatinget Skid-Mounted Evaporation Units: Minetek provides versatile units for different settings. These include land-based, floating, and skid-mounted options.
• Epoxy, Stainless, and/or Galvanised Steel Construction Materials: Durable materials ensure longevity and reliability in harsh operational environments.
• Fully Integrated Environmental Management System (EMS): Integrated EMS ensures compliance with environmental standards, enhancing operational efficiency and regulatory adherence.
• Cost-Effective Solution: Minetek’s evaporation technology is approximately five times more cost-effective than traditional methods, offering economic benefits and environmental stewardship.

Minetek’s advanced evaporation technology is an important solution for the environmental challenges of global mining and can help improve efficiency and reduce costs at your site. For more information, download the eBook!