DRY TAILINGS STORAGE

Worldwide, it is estimated that there are an average of two tailings dam failures every year. In Australia, the regulatory environment has made it extremely difficult to build a new dam. These are indications that current practice is not working to the level required. Not only can tailings storage work better, but it can also be done economically.

Modelling the lifetime costs and the financial risks of wet tailings storage is a challenging task. Variables include rainfall, evaporation, seismic activity, seepage, mine production rate, rheology, etc. just to name a few obvious ones. It becomes even more complicated and costly if you consider closure, rehabilitation, the unpredictability of developing regulations and the “social license to operate”. 

Calculating the cost of a tailings dam failure is also a challenging task for many reasons. For a period, the Brazilian government pursued homicide charges against senior executives in the aftermath of the Samarco tailings disaster. Can you input “cost of homicide conviction of senior executives” into a financial risk model? This is an extreme example, but it highlights the social cost of such an event.

Storing tailings in a dry state eliminates these risks and there is a geosynthetic technology developed in the early 90s that efficiently facilitates dry tailings storage while offering many other benefits to a mining operation.

Geotube® Dewatering Units are large porous containers that are designed to efficiently retain solids and allow fluids to pass. The technology has been used worldwide to dewater and contain mine tailings safely and economically. This solution improves risk, environmental impact and cost when compared to a traditional tailings dam.

Decreased Risk

• Geotube® dewatering technology eliminates the risk of tailings dam failure. This risk is particularly significant in areas of high seismic activity and variable rainfall
• A Geotube® solution is easily scalable thus reducing the risk of mine operations scaling beyond the capacity of the tailings dam

Improved Environmental Impact

• Storage of dry tailings in containers which can be stacked significantly reduces the total required footprint
• With the dam failure risk eliminated, the potential for an environmental disaster is significantly reduced
• Geotube® Dewatering System allows for monitoring and environmentally friendly re-use, treatment or disposal of effluent water
• Geotube® Dewatering System offers greater flexibility for placement of tailings
• Geotube® Dewatering System allows minimal groundwater seepage

 Lower Cost

• Lower up-front capital expense allows improved financing as the mine is actively generating returns
• Improved access to dewatered tailings for secondary processing or salvage value
• Eliminates the cost of tailings dam monitoring and insurance
• Scalable to match production rates
• Beneficial use of Geotube® Dewatering Units for bunding and containment structures
• Lower rehabilitation cost
• Improved water recovery

At the Geofabrics lab in Gold Coast, Queensland, our team tests tailings slurry samples to evaluate and optimize dewatering options. Prior to lab testing, we can advise on the suitability and scale of a Geotube® solution based on some basic inputs such as slurry volume and solids concentration.

For more information, contact the author or your local Geofabrics branch.