Blog: Reasons why dry tailings is important 1/3
Posted on Friday, 27 November 2020 at 16:52
In the next few weeks we will share more information about the important reasons for density measurement in the process of dry tailings, and how important it is to maximize the water recovery in that process.
In order to extract valuable minerals, mining companies have to move large amounts of earth. The waste resulted from this process is usually stored in a large pond, as a semi-liquid known as tailings. It is expected that these ponds are stable enough to withstand the pressure of the stored material, however, unfortunately history shows that this is not always the case. Some dam failures in 2015 and 2018 resulted in the loss of many lives and an environmental destruction on an unprecedented scale.
Current generation engineering have shown that an alternate process known as dry stacking is a practical solutions to semi-liquid tailings. In addition to achieving the dry tailing benefits, it is possible to recover valuable process water while dewatering the tailings sludge utilizing modern separation technology.
With environmental sustainability being seen as a key factor in modern mining, the method of dry stacking tailings is becoming increasingly popular. Dry stacking can eliminate concerns related to potential dam failures. According to CRC Care 2013, every year more than 10 billion tons of tailings are produced by mining activity. Globally, many mining sites struggle due to insufficient amounts of fresh water intake available in their regions; the dewatering process can capture as much as 90 percent of the water for reuse.
Dry tailings are typically achieved through a multi-step process. The sludge is thickened or concentrated through gravity settling in a thickener. The concentrated sludge is withdrawn from the bottom and clarified water exits through the overflow of the thickener. The thickened sludge is then processed through one of several types of mechanical dewatering machines to achieve dry tailings for stacking. Three devices proven to have various degrees of success with dewatering the thickened sludge are: belt presses; plate and frame chamber filter presses and decanter centrifuges.
Main benefits of dry tailings:
- Optimized footprint of tailings storage and minimized fresh water intake
- Reduced dam construction with decreased operational costs
- Lower tailings risks and insurance rates
- Easier permitting and socio-political acceptance
- Low environmental impact and savings at the rehabilitation
- Resistance to high seismic activities
Please contact Rhosonics if you want to know more about the importance of density measurement in the dewatering process.
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Source: website Outotec