Trevali Mining reported in late March that it has re-started mining activities at its Caribou underground zinc-lead-silver-copper mine and mill complex in the Bathurst mining camp of northern New Brunswick, Canada and that commissioning of the mill would begin during the second quarter. Trevali acquired the inactive Caribou operation from Maple Minerals in November 2012. The mine and mill had operated for approximately 13 months prior to going into receivership in 2008 due to depressed commodity prices.
As of late March, the Caribou milling circuit was predominantly refurbished and ready for operation, with a new 3,000-mt/d SAG mill installed and aligned. The two ball mills had been refurbished, and the three M1000 IsaMills had been inspected and were in excellent condition.
The zinc and lead flotation circuits and associated pumps had been refurbished or replaced and were ready for commissioning. Design for a new copper circuit had been completed and tendered, with the majority of equipment sourced and on-site. During the commissioning period, Trevali will focus initially on the established zinc and lead (plus silver) recovery circuits, following which it will commission the copper circuit.
Initial underground mine production was underway, with blasting of the first scheduled stope and transport of mineralized mill feed to the surface stockpile. The company planned to build a significant stockpile of mineralized material (approximately 60,000 to 80,000 mt) prior to beginning mill commissioning.
Approximately three years of underground development was in place in the mine. Ramp, level rehabilitation, and access to the first four production zones was 100% complete, and rehabilitation of the fifth zone was approximately 80% complete. Approximately 1 million mt of mineralized material was available for production.
As part of Trevali’s ongoing Impact Benefit Agreement with local Mi’kmaq First Nations, mining and mill training programs have been initiated to provide qualified First Nation candidates with the skillsets to take advantage of Trevali’s goal of 20% First Nation workforce participation at Caribou. Trevali expects to be one of the largest First Nation employers in New Brunswick.
Trevali is finalizing detailed plans for an approximately 10,000-m underground resource conversion and expansion drill program at Caribou to begin in second half of 2015. The primary aim of the campaign will be to convert a significant portion of the currently defined 3.66-million-mt inferred resource to indicated or higher confidence levels.
Trevali also reports that exploration drilling has intersected significant massive sulphide mineralization approximately 200 m outside the Caribou mine’s currently defined measured and indicated resource. Drill hole BR-1014A was designed to test the northwest, down-plunge extension of the “Caribou Mineral Horizon” at intermediate depths, which remains relatively underexplored. The hole intersected 50.9 m of massive sulphide mineralization at a downhole depth of 607 m (vertical depth of approximately 550 m), grading 5.08% zinc, 1.76% lead, 0.37% copper, 59.66 g/mt silver, and 1.63 g/mt gold. Several higher-grade intervals occur across the length of the hole. Followup drilling is planned.
Facilities layout at Stornoway Diamond’s Renard project in Quebec. (Photo courtesy of Stornoway Diamond Corp.)