Mining and ore processing activities produce waste by-products including waste rock (overburden that has no economic value) and tailings (the material that remains after the minerals have been extracted from the crushed ore).
All Hudbay operations have plans in place to reduce, reuse, recycle and responsibly dispose of hazardous and non-hazardous waste, with a particular focus on managing waste rock and tailings. (A more detailed discussion on tailings management is included in the Tailings Stewardship section of our Integrated Annual and CSR Report.)
Sites must manage waste rock in accordance with environmental regulations and industry standards and in a manner that minimizes the potential for acid rock drainage, which is caused by a chemical reaction when certain minerals in some types of rock are exposed to air and water. Some waste rock and tailings may be classified as potentially acid generating (PAG). To minimize and mitigate the impact of PAG-classified material, wherever possible we use PAG-classified waste rock to fill voids in underground operations or dispose of its facilities engineered to prevent acidic runoff. We use non-PAG waste rock for a variety of purposes, including building tailings containment structures, as backfill for open pits, site rehabilitation and also to fill underground voids.
Details on our tailings facilities are available in our Mine Tailings Disclosure Table.
Towards Sustainable Mining Protocol
As a member of the Mining Association of Canada (MAC), Hudbay follows the Towards Sustainable Mining (TSM) program and is implementing an updated tailings management protocol consistent with TSM’s updated protocol at all of our operations. Our protocol builds on a continual improvement process for tailings management to achieve the goal of zero catastrophic failures of tailings facilities and no significant adverse effects on human health or the environment. The protocol emphasizes management processes, senior executive oversight, and expert third-party reviews that ensure appropriate technical standards of construction, maintenance, and operation.
Tailings Governance Charter
In 2018, we developed a Tailings Governance Charter to further strengthen our internal governance processes related to tailings management, to ensure the appropriate processes are in place and that all of our tailings facilities are constructed and operated in a manner that protects public health and safety. At present Hudbay has seven tailings and water retainment structures/facilities — four in Manitoba and three in Peru. These are managed in accordance with the requirements of the Charter. The reviews and inspections in 2018 found all facilities and structures were in compliance with our standards and best practices.
The Manitoba and Peru business units maintained their TSM ratings (AA and A, respectively) across all the tailings management indicators in the 2018 TSM Progress Report. Both business units are updating their tailings management processes in preparation for reporting against the new requirements in the updated protocol.
Rosemont Project
At our Rosemont project in Arizona, we plan to use an alternative method of tailings disposal called dry-stack or filtered tailings. This method — which involves dewatering tailings prior to placing them in a storage facility — offers numerous advantages over other tailings storage options, provided climatic conditions support the technology. These include reduced requirements for water consumption and land and the ability to conduct concurrent reclamation. Dry-stack also nearly eliminates the risk of groundwater contamination and catastrophic tailings dam breaches.
Rosemont’s state-of-the-art dry-stack tailings facility will be one of the largest in the world, requiring half the water for twice the production, thereby establishing new standards for responsible mining.