Innovative water treatment solutions in the mining industry

The mining industry faces ongoing challenges in managing water resources efficiently, particularly as environmental regulations become more stringent and water scarcity issues intensify. According to industry reports, the global water treatment market in mining is projected to grow significantly, driven by the increasing need for sustainable practices and cost-effective solutions.

Mining operations often take place in remote and arid regions where water is scarce and typically laden with high levels of suspended solids. Efficient water treatment systems are critical not only for the mining processes themselves but also for ensuring the availability of potable water for workers at mining camps.

Traditional filtration methods: Limitations and challenges

Many mining operations rely on traditional filtration methods such as sand filters, which can be either pressure sand filters or gravity sand filters. Gravity sand filtration systems involve constructing large civil pool-shaped structures filled with sand through which water is sent to filter out impurities. However, this method has significant drawbacks:

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• Space requirement: Sand filters require substantial physical space, which can be a constraint on many mining sites.
• Maintenance and downtime: The sand in these filters needs to be replaced periodically, which can require up to two to three days of downtime. This maintenance involves machinery, teams of labour, and other resources. One day of downtime can cost a mine substantial amounts of money, running into thousands or even millions of dollars, depending on the size and productivity of the mine.

Advanced filtration technologies: VAF™ V-Series Self-Cleaning Screen Filters

Emerging technologies such as the Evoqua self-cleaning VAF™ (Vortex Automatic Filter) present a revolutionary solution to these challenges. These filters operate without requiring downtime, offering continuous operation. Here’s why the VAF filters are becoming a preferred choice in the mining industry:

1. Continuous operation and self-cleaning: The VAF filters can automatically self-clean without halting the filtration process. This system is designed to ensure that at least 95% of the water continues to be filtered while only 5% is used in the cleaning process. The flush cycle takes a mere 15 seconds, ensuring minimal disruption.
2. Efficiency and space-saving: Unlike traditional sand filters, VAF filters do not require large spaces. For instance, six VAF filters are capable of filtering 1000 cubic meters per hour at 50 microns which can be housed in a standard 12-metre container. This compact footprint is highly advantageous for mining operations with space constraints.
3. Minimal maintenance requirements: The VAF filter system does not rely on hydraulic systems, motors, or any electrical mechanisms to perform self-cleaning. Instead, it utilises a simple pressure difference between the water pressure in the filter and atmospheric pressure when the flush valve is opened to drive the cleaning mechanism. This simplicity reduces the risk of mechanical failures and the need for replacement parts or specialised technicians, which is crucial for mines located in remote areas.

How the VAF filter works

The operational mechanism of the VAF filter is ingeniously simple and effective:

• Filtration process: Dirty water enters the filter and passes through a coarse screen and then a fine screen, where impurities are trapped. Clean water exits through the outlet.
• Self-cleaning cycle: As impurities build up, the pressure drop across the fine screen increases. Upon reaching a preset differential pressure (0.5 bar), the filter controller initiates a flush cycle by opening a flush valve. This valve reduces the pressure in the flush chamber to atmospheric pressure, creating a suction effect that removes dirt from the fine screen.
• Suction and rotation: The dirt collector, equipped with suction nozzles, rotates due to water jets acting as a reaction force. This rotation ensures comprehensive cleaning of the screen, with each nozzle cleaning a specific band of the fine screen. A reverser mechanism ensures the dirt collector moves back and forth, providing complete coverage and efficient cleaning of the screen.

Advantages of VAF filters

The VAF filters offer several significant benefits that make them particularly well-suited for the mining industry:

• Reduced moving parts: With 70% fewer moving parts compared to traditional systems, VAF filters have simpler controls and lower maintenance needs.
• Efficient cleaning: The patented design ensures 100% screen cleaning with controlled suction nozzle rotation, resulting in greater cleaning efficiencies and lower flush waste (less than 1% of system flow).
• Versatile applications: VAF filters can handle individual flow rates ranging from 7 to 2,274 cubic metres per hour, with filtration capabilities from 10 to 1500 microns. These systems can be pre-assembled to meet any flow demand and can serve as pre-treatment steps before microfiltration for cleaner water.

In conclusion, the adoption of innovative water treatment technologies such as the Evoqua self-cleaning VAF filters represents a significant advancement for the mining industry. These systems offer a reliable, low-maintenance, and space-efficient solution to the challenges posed by traditional filtration methods, ensuring continuous operation and improved water quality. As the industry continues to evolve, embracing such technologies will be crucial for sustainable and profitable mining operations.