Understanding mine remediation

The risks of water pollution

Water is one of the world's most precious resources, yet it is often taken for granted. In many parts of the world, access to safe drinking water is not a guarantee for many people. More than 2 billion people in the world currently lack a source of safe water, while around 80% of the world's wastewater is dumped—largely untreated—back into the environment, polluting rivers, lakes, and oceans. Polluted water kills more people each year than natural disasters or conflicts, highlighting the risks of contaminated water leaking into our environment.

Water is essential in most mining and extractive processes, making responsible water use a critical business issue for the industry. Mining operations use large amounts of water to process ore, and water pollution from discharged mine effluent and seepage from tailings and waste rock impoundments.

As water is essential in most mining and extractive processes, responsible water use is a critical business issue.

The need for mine remediation

The mining industry's use of and impacts on water can result in various environmental, social, and economic risks if handled poorly. The improper disposal of water containing pollutants can result in heavy fines and irreparable harm to a company's reputation. More worrying, however, is the environmental impact of incorrect water disposal, which can have devastating consequences for rivers, streams, and aquatic life for hundreds and possibly, thousands of years.

When excavating coal, metal ores, or other minerals, rocks and minerals that contain sulfur may be exposed to water and oxygen, causing groundwater to become acidic. This process is called acid mine drainage. Acid mine drainage contains highly polluting substances such as lead, zinc, iron, mercury, and cadmium. The highly toxic water has the potential to poison downstream waters and destroy already fragile ecosystems

What is mine remediation?

Rehabilitation is an integral component in the life of mine.

Before the commencement of any mining operations, mining companies work with government authorities to develop comprehensive rehabilitation plans which determine the post-mining use of the land and include objectives to return the resulting landform to a safe and stable condition.

The increasing push toward sustainable mining practices has seen mine remediation come to the forefront in recent years, with the global market for environmental remediation forecast to grow at a CAGR of 7.5% to reach US$152.23 billion by 2025.

Remediation projects can include the following:

● Treatment or removal of soil, sediments, groundwater, or surface water

● The demolition and removal of unused infrastructure

● The upgrading of dams to protect against tailings spills

● Engineered soil coverings for tailings ponds and waste rock piles

● Water treatment system upgrades to keep contaminated water out of the local watersheds

While effective and sustainable groundwater management of this toxic outflow is traditionally expensive, it is critical during any minerals processing application, with leachates and sulphidic mine wastes posing a significant commercial and sustainability risk for mining operations.

How can enhanced water evaporation assist with mine rehabilitation?

Water evaporation is a natural process of converting water from liquid to vapor. The evaporation process may be carried out naturally in solar evaporation ponds. While this approach has benefits, the slow process requires much land area. The cost of completing additional storage ponds and the added cost of clean-up and revegetation are often prohibitive.

Mechanical water evaporation is another approach that can be used to remove water from surfaces, dams, and tailing storage facilities. This is often done to prevent corrosion or dispersion of harmful metals and chemicals into the environment.

The MINETEK evaporation system functions by discharging water through a unique and patented water fracturing nozzle. This nozzle is designed to achieve the correct water molecule size by fracturing to maximize performance via droplet reduction and direct water fragmentation. The water is then injected into a high volume/high-velocity air stream to propel it into the atmosphere. Enhancing hang time and exposure to external- ambient elements.

This is a continual process of replenishing ambient air via a high-performance vane blower unit within the Evaporator. Drawing air from fresh ambient surroundings maintains and achieves the highest possible evaporation.

With the capability to evaporate water with high levels of Total Dissolvable Solids (TDS) and Total Suspended Solids (TSS) and pH range as low as 1.8 and as high as 14, MINETEK's water evaporation solutions offer versatility and a cost-effective solution to managing Multi-Aquifer Well (MAW).

The Benefits of MINETEK’s Mechanical Water Evaporation

Mechanical water evaporation provides a significant range of benefits when compared to solar evaporation ponds, including:

● It is a natural process that does not require chemical pre-treatment

● It is very efficient at removing water from surfaces

● Significant CAPEX savings

● No waste stream

● No operator required

● Quick deployment of systems

● Very low maintenance

● Not susceptible to changes in feed water quality

● Minimal footprint and power required

● Evaporators a very mobile and robust

For the sake of complete transparency, mechanical water evaporation also has some disadvantages. To begin with, it can be a slow process, especially when evaporating large quantities, meaning it is not a suitable solution for applications where water needs to be removed quickly. Instead, it is much better suited to long-term water management solutions.

Conclusion

If left unaddressed, acid mine drainage can have long-lasting consequences on the environment. With proper care, however, there are ways of reducing the negative impact of acid mine drainage.

MINETEK has developed a cost-effective method to manage acid mine drainage with our wastewater evaporation solutions used worldwide by leading mining operations.

Interested in learning more about our recent water management projects or water evaporation case studies?