Abstract:

Advance Reclaim Inc. (ARI) has developed a process philosophy that promises to assist in the elimination of the need for long-term tailings facilities beyond 20 years after the cessation of production. This process will contribute to the transformation of the mining industry that is essential if it is to supply the Green Transition to a low-carbon economy by 2035. The electrification of the economy to reduce GHG emissions will require many more metal mines to come into production, but opposition to new mines because of the social and environmental impact of their tailings management practices now presents an unsustainable delay. The required life of a typical tailings storage facilities is over 1000 years, and a containment system that does not rely on perpetual maintenance with the risk and liabilities associated with human error is difficult.

The ARI process recognizes that in many cases 80% of the material in typical mine waste stream is benign and that separating out this material from the problematic 20% reduces the volume of material that requires sequestration in a conventional tailings storage facility. Recent developments in mineral processing technology have made it possible to combine various techniques into a process that ensures the hazardous chemicals and valuable solids can be separated from the benign minerals. This divides the waste stream in to a highly contaminated tail (HCT) that hosts almost all of the hazardous material in the waste stream and a tolerably benign tail (TBT) that has very low levels of any kind of contaminant. The TBT material can be safely and securely stored in a relatively inexpensive, low-technology containment facility, possibly with a vegetative cover that is not affected by the extremely low level of residual contaminants in the TBT. The TBT could also be processed in a series of bio-reactor cells that create a completely benign tail (CBT) that is suitable for use in agriculture and forestry, and so generate carbon credits.

The HCT can be processed by a variety of new industrial processes that either recover the residual value in the HCT or make the remaining material inert and ready for storage in a hazardous waste site. This material could be processed continuously over the life of the operation so that the total volume of material stored in the conventional tailings facility at any one time is only 20% of the total life-of-mine volume of the HCT (20% by volume). This is roughly 4% of the material permanently stored in a conventional tailings facility. Continuing the re-processing of the HCT after the cessation of production, this storage facility eliminates the last of the waste steam and promotes the permanent closure of the site within 20 years of the end of production. This process of separation, sequestration and treatment (SST) of the mineral processing waste stream offers the opportunity to restore the land and water resources to a variety of end uses determined by stakeholders and offers a key resolution to the conflicts that arise between mine, agricultural and indigenous communities.

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Vernon Drylie