Managing Mine Tailings: Filter Press Fabric for Effective Dewatering
In the mining industry, tailings management is essential. If tailings are not managed properly, the substances escape into the environment harming people and the water supply. In addition, businesses can incur penalties for poor management. So what are tailings, and how can they be managed?
First, what are tailings? Tailings are a byproduct of mining operations. After the valuable metal such as gold or iron is extracted from the mined material, the left behind waste is called “tailings.” These tailings—consisting of water and fine mineral particles—are large in quantity. For example, for every ton of hard coal produced, there is a byproduct of ½ tons of waste. If the tailings solution is left untreated, the material can produce acids upon air contact. This acid drainage is harmful to the local surface and groundwater supply.
The Problem with Tailings Dams
A popular tailing management method is to use a dam. Commonly, the tailings in this management system are 1-2 parts solid and 1-2 parts water. The substance is transported to the dam, where it is then contained. These dams can be useful. A cheap, popular dam construction method is to use the tailings themselves as the dam’s foundation. The dams cause problems if the tailings fill with water and collapse. Since they make up the foundation, the failure can be catastrophic to the local environment, not to mention lead to penalties for the business.
Moreover, the volume of tailings in the dams is only growing. And while tailings dams are not constantly failing, they do fail more than 100 times more often than reservoir and power dams. In addition to dam failure, the tailings’ exposure to air and water within the dam can generate acid runoff. Plus, mining operators face increasing regulation to minimize environmental impact.
So, what are the other options?
As it sounds, dewatering tailings means removing water from the tailings. Dewatering offers a more reliable tailing management system. Also called dry stack tailings, the dewatered substance can be stacked and stored. This process:
- Reduces the risk of groundwater contamination that occurs with dam seepage
- Requires less land for tailing storage
- Cuts business costs by reclaiming water
There are more energy savings that come with dewatered storage. When water is removed, the tailings volume is decreased, allowing for easier transportation to a tailings storage facility (TSF). Due to lesser volume, smaller pipelines, and pumping equipment can now be used when transporting the substance from the process plant to the TSF. The smaller tailings volume also reduces the power needed to transport it, increasing the business’s efficiency.
Below are some different dewatering methods.
This cost-effective method can remove large quantities of water from the tailings. They are simple to maintain, not too expensive, do not require added chemicals, and rely on centrifugal forces to get the job done. However, they can only remove some particle sizes—so when using this method, you will need to supplement it with another one for complete dewatering.
This method has a smaller footprint and is not too expensive initially. The tailings are dewatered by moving between two moving, tensioned belts. And although initially, they are not too expensive, operating costs are high as lots of chemical flocculants are required to keep it running. The belts also wear down quickly, increasing maintenance and system downtime. In addition, the dry cakes produced after dewatering may need further processing before heading to dry storage.
In this method, tailings are pumped in and then pushed through filter plate chambers. This system can use either high or low-pressure, but low-pressure presses are often less efficient and necessitate complicated designs. The filter press features lower power use and a high percentage of mining water recycling—up to 80%. It is also easier and safer to run than a tailings dam. The resulting dry cakes are easily removable from the filter cloth and do not leave any residue behind.
Filter presses also work well at higher altitudes, making them a compelling choice for more remote sites.
Mining Filter Press Maintenance
A good quality filter cloth should last for hundreds or even thousands of cycles. This is especially true when the filter cloth is designed for the application. Periodically inspecting and cleaning the filter maximizes its life span.
The cloth should be rinsed with clean water weekly, to wash off material buildup—especially around the edges and corners of the fabric. In rare cases, filter cloths should be cleaned after each cycle to maintain efficient operation. In addition, if the filter press hasn’t run for a few days, the filters should be cleaned to prevent dry material buildup. The dried buildup is much harder to remove.
Inevitably, filter cloths will need to be replaced when they wear out. Filters should also be checked at least once a week for holes or tears. A clear sign of a hole in the cloth is water that comes out cloudy near the damaged filter. Once a tear has occurred in the filter cloth, water passing through the ripped filter can cause accelerated damage and even harm the filter plate. Thus, when damage is cited, the material should be repaired or replaced as soon as possible.
When managing mine tailings, the filter press is a tried and trusted method. It saves water and enhances mining efficiency, and is much safer than using a tailings dam. Ready to revolutionize the way you manage your mine tailings? Contact Filter Holdings today to learn more about our innovative filter press fabric solutions.