Environment Waste and
Tailings

All Hudbay operations have waste management plans to reduce, reuse, recycle and responsibly dispose of waste. Waste rock from our mines and tailings from processing plants are a particular priority.

Waste rock is the mined rock that does not have economic value. It is managed on-site according to strict and detailed environmental regulations and industry standards. Wherever possible, it is reused as fill in underground operations and site rehabilitation.

Tailings are the finely ground rock, trace metals and process chemicals remaining after ore has been processed. Hudbay adheres to the Mining Association of Canada’s highly regarded TSM protocol for managing tailings. Where water is plentiful, tailings have historically been piped into secure engineered impoundments contained by tailings dams. TSM guidelines address best practices for the location, design, construction, operation and closure of tailings facilities so that structures are stable and comply with industry and government standards, and solids and water are properly managed. Independent reviews are conducted on our tailings management design and practices in Saskatchewan and Manitoba and at Constancia, in accordance with the TSM protocol.

Safety measures used at our Flin Flon Tailings Impoundment System (FFTIS) and Constancia Tailings Management Facility (TMF) include the following:

• Frequent inspections by trained Hudbay personnel.
• Comprehensive inspections by third-party geotechnical engineering consultants.
• Deposition plans produced by third-party engineering consultants to manage projected tailings production.
• Detailed geotechnical designs for annual construction on the dams, completed or validated by third-party consultants and approved by regulators.
• An independent quality assurance/control monitoring program is in place during dam construction.
• Upon completion of construction, detailed as-built engineering drawings are produced by the geotechnical engineering consultant, validated and submitted to regulators where required.

In consideration of the environmental conditions in Arizona, Rosemont plans to construct a state-of-the-art, dry-stack tailings facility, which would use significantly less water than traditional facilities, allow for better dust control, be significantly more stable and reduce the potential of environmental impacts to groundwater. The use of dry-stack tailings will also allow more effective and earlier rehabilitation of the tailings area.

2015 Performance Highlights

Corporate

• Hudbay manages tailings in accordance with the TSM Tailings Management Protocol and guidance documents. The protocol and documents were recently reviewed by an independent task force, and 29 recommendations were brought forward. We are participating in MAC’s work to determine how the recommendations will be implemented and how they will affect us.

Manitoba

• We conducted a community information campaign as part of the Environmental Assessment process for a planned expansion of the Anderson tailings impoundment area (TIA) to accommodate tailings through the life of the Lalor mine. The new infrastructure will include additional water retention dams, a seepage collection system and associated pump houses, and a new spillway to replace the existing one. We must submit an Environmental Assessment (EA) to Manitoba Conservation and Water Stewardship for approval before work can begin. The EA addresses all physical, aquatic, terrestrial and socio-economic factors related to the expansion.

Peru

• Construction of the Constancia Tailings Management Facility (TMF) advanced far enough to permit the storage of the required water inventory for the start of operations and the deposition of tailings in the east TMF impoundment. Construction of east and west embankments will be a feature of ongoing Constancia operations during the life of the mine. Tailings pumping and deposition facilities performed as designed during early production.
• In 2015, we commissioned a third-party engineering consulting firm to conduct a geochemical study of waste deposition. The firm’s recommendations, which were subsequently implemented, were to place non-acid generating material in the exterior boundary to minimize the potential for acid rock drainage.

Arizona

• We plan to use the best available technology applicable to site conditions in the proposed dry-stack tailings facility. In 2015, our study of potential filtering systems included a visit to Australia to see how the technology is being used in mines there.