Name and Location
Caribou zinc/lead/silver mine and mill complex, New Brunswick, Canada.

Client
Trevali Mining Corporation.

Project Description
The base case preliminary economic assessment (PEA) on the Caribou project has indicated positive economic results.

The project involves the restart of the Caribou mine project, through the reactivation of the 3 000 t/d Caribou mill complex and the associated underground deposit.

Underground operations will take advantage of the existing extensive historical development and infrastructure. A centralised ramp-trucking system will serve as the main access for the mine. The main mining method will be modified Avoca with waste-rock backfill, with the exception of a long-hole retreat mining method for partial sill pillar recovery near the end of the mine’s life.

The processing circuit will consist of the 3 000 t/d semiautogenous grinding and milling circuit, including fine-grinding IsaMills, with standard sulphide flotation recovery circuits to produce three concentrates – zinc, lead/silver and copper/gold. The average life-of-mine (LoM) modelled head grade for mill feed is 6.11% zinc, 2.49% lead, 0.34% copper, 67.9 g/t silver and 0.86 g/t gold.

LoM metallurgical recoveries used in the PEA are 84% for zinc, 65% for lead, 45% for copper, 37.5% for silver and 10.6% for gold. No optimisation of precious metal recoveries has occurred to date but is being evaluated.

Value
Preproduction capital expenditure is estimated at $36.3-million.

Duration
Commissioning of operations is expected in the first half of 2015.

Latest Developments
The Caribou mine and mill complex project remains on track and within budget, with commissioning still expected to start in the first half of this year.

Trevali has reported that the new 3 000 t/d semiautogenous grinding mill and associated components have been installed and the mill will be commissioned over the first three months of 2015.

The Xstrata process support group has inspected the three IsaMills installed at Caribou and has been found to be in excellent condition for start-up. The company is proactively replacing the electric motor bearings for enhanced reliability during commissioning.

The zinc and lead flotation circuits have been cleaned and repaired where necessary, and the copper circuit design and tendering is nearing completion.

All the mill’s motors and electrical drives have been cleaned and serviced by original-equipment manufacturer representatives.

Further, the pumps have been refurbished and/or replaced, and spare pumping capacity components have been sourced from the nearby Brunswick-12 mine and mill complex that was shuttered in 2013.

Plant instrumentation refurbishment is also ongoing as equipment becomes available and remains on track to be commissioned with the mill.

In terms of underground development, construction of the new portal started early in November and is advancing to schedule. The tunnel is expected to break the surface 100 m from the fine mineral bins in the first quarter, reducing the previous overland haulage route by about 1.5 km.

This is expected to result in lower haul costs, improved underground fleet availability and improved winter production capabilities.

Meanwhile, about three years of underground development is in place.

The ramp and level rehabilitation are about 90% complete and access to two of the first four production areas is about 75% complete. The third and fourth production zones are 40% to 50% complete and are continuing to progress to schedule and plan. There is currently about 600 000 t of mineralised material available for production.

The surface crusher is being installed on a newly designed radial stacking pad. Based on the company's experience with commissioning the Santander zinc/lead/silver mine, Trevali is planning to stockpile about 60 000 t to 80 000 t of underground material before starting the second-quarter mill-commissioning activities.

The mine’s main dewatering pumps are fully installed, dewatering the site at a rate of about 2 271 l a minute. The mine is currently dewatered to about 250 m below surface.

The underground paste backfill study is also advancing and results are expected in the first quarter.

Other surface activities are also progressing, including refurbishing the zinc/lead concentration shed and replacing several bridges on site to improve access to the tailings management facility. The reclaim pump station and water polishing pond areas have been raised and placed on new foundations in anticipation of potential future expansions to the facility.

Key Contracts and Suppliers
SRK Consulting (Canada), in collaboration with Trevali (underground mine modelling, general and administration costing and project economics), Stantec Consulting (environmental and permitting), Holland & Holland Consulting (metallurgical and processing).

On Budget and on Time?
Not stated.

Contact Details for Project Information
Trevali Mining Corporation, tel +1 604 488 1661, fax +1 604 408 7499 or email info@trevali.com.
SRK Consulting, tel +1 604 681 4196, fax +1 604 687 5532 or email vancouver@srk.com.
Stantec Consulting investor relations, tel +1 780 969 3349 or email investor.relations@stantec.com.