The application of this technology has accomplished: (i) an increase in tailings water recovery, (ii) a reduction of the TSF footprint (impacted areas), and (iii) a decrease in the risk of physical instability, being TSFs self-supporting structures under compaction (such as dry stacks), and (iv) a better regulator and community perception satisfying the need of stable TSFs. This technique produces an unsaturated cake that allows storing this material without the need to manage large slurry tailings ponds. In the last 20 years many mining projects around the world have applied a tailings deposition technology named “dry stacking of filtered tailings” at tailings storage facilities (TSFs). For the minority set of projects that can find a non-slurried tailings alternative advantageous to optimal permitting and/or operating conditions, filtered tailings are often an excellent alternative. Development of large capacity vacuum and pressure filter technology has presented the opportunity for storing tailings in an unsaturated state, rather than as conventional slurry and/or in the "paste like" consistency associated with thickened tailings. However, with advances in dewatering technologies over the past few decades, that tailings slurry is actually being only part of a continuum of tailings "states" available to the modern tailings designer. These facilities are developed using tailings slurries that are the end waste product of the milling process. Conventional tailings impoundments remain the best alternative for the majority of operating and proposed mines around the world. This pressure to seek alternative tailings management approaches exists today and the future will likely only see these pressures intensified. The amount of water that is "lost" to the voids in the stored tailings, seeps or evaporates from the tailings impoundments is something being increasingly viewed by critical regulatory and public eyes that insist on evaluating whether there are viable alternatives for any given proposed mining development. As the future of mining includes increasing scrutiny on the industry's stewardship of the natural environment, including use of water in most regions in the world, a commitment to alternatives beyond impoundments is often sought. Following operating these complex entities, closure of these impoundments can represent significant challenges in terms of both physiochemical reclamation as well as geotechnical considerations. These impoundments require construction and maintenance of structural integrity for the retention structures as well as management for what are typically immense quantities of water. These impoundments are developed to store tailings slurry that typically arrives at the impoundment at solids contents of about 25% to 60% depending upon whether any thickening is carried out prior to deposition. FILTRATION-END MEMBER OF THE TAILINGS CONTINUUM The vast majority of the world's tailings facilities involve tailings impoundments. The guidelines include specific reference to "lessons learned" from existing operations that will benefit designers and owners alike. Issues related to target moisture content, appropriate testing methods and criterion, geotechnical conditions and placement considerations are included. These guidelines are based upon the successful conceptualization, design, and operating experience at a number of these facilities. This paper provides practical guidelines for the design and development of filtered dry stack tailings facilities. The reason for this lack of guidance materials is uncertain but it has led to some unfortunate tailings management decisions based on misinformation about dry stacked tailings facilities in general. ![]() There are more filtered dry stack tailings storage facilities than there are surface paste facilities yet the amount of guidance documentation on filtered tailings is virtually non-existent in compare to those same paste tailings facilities. ![]() Filtered tailings are becoming an increasingly common consideration for tailings management at many mines.
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