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A Sudbury-area zinc deposit that was once considered unprofitable is now getting a second look because of modern mining and metallurgical technologies.
Xstrata Zinc is currently undertaking simultaneous pre-feasibility and feasibility studies on the Errington and Vermilion mineralization in preparation for a $350-million development that would produce an estimated 2,900 tonnes of ore per day over a seven- to 10-year mine life. The development is expected to create between 200 and 250 jobs.
“Errington and Vermilion don’t have nickel; they’re polymetallic zinc deposits,” said Aline Côté, project director for Xstrata Zinc, during a luncheon to cap off Sudbury Modern Mining & Technology, a week dedicated to raising the profile of the industry amongst area youth.
“To my knowledge, there are very few other zinc anomalies in the entire Sudbury basin.” Both deposits contain zinc, copper, lead and “a fair amount” of precious metals, she added.
Mined for a brief period following their discovery in 1924, the Errington and Vermilion deposits are located west of Sudbury along the Vermilion River and Vermilion Lake.
To date, Xstrata has done 40,000 metres of diamond drilling, and the anomaly is larger than expected. The Errington deposit has 5.8 million tonnes of ore, while the Vermilion deposit has 2.5 million tonnes of ore. Although the Vermilion deposit is smaller, it’s considered a richer mineralization.
The deposits have an intriguing history.
Errington, which was discovered first, was mined from 1924 to 1928. It was deemed such a substantial deposit that an entire village and concentrator site were built around it. More than 8,000 lateral metres and three shafts were developed at the time, Côté said.
It shut down because of the major capital investment required to extract the deposit’s fine-grained material.
“That is one of the challenges that was definitely faced in the 1920s in regards to making the ore profitable,” Côté said. “Gladly, with new mining technology and new metallurgical technology, we can now make this work.”
Vermilion was exploited in the 1950s, but had less infrastructure built around it. Combined, 120,000 tonnes of ore were extracted from the two deposits over a one-year period.
Xstrata has spent more than a year going through historic data—paper logs, drilling results, underground and surface mappings—dating from the 1920s to 1990, which was the last time Falconbridge drilled on one of the properties, Côté said.
The development concepts Xstrata are studying now recycle the underground lateral infrastructure at both sites, she noted. Errington-Vermilion would be developed as one project with Errington developed at the start of the mine life; the mineralization is made up of five different lenses that would be mined sequentially.
Development would ramp up to Vermilion two years prior to the end of Errington’s mine life, Côté said. Vermilion presents its own “unique challenge,” since the deposit is located directly under Vermilion Lake.
In an effort to minimize the project’s footprint, Xstrata plans to reuse its existing infrastructure, trucking the ore to the Strathcona mill site for processing.
“Because of what would be processed at Strathcona, it’s not wise to have a zinc circuit next to a nickel circuit, which is why the mill or concentrator that would be built for Errington-Vermilion would be completely separated from the existing facilities to make sure that there’s no contamination of concentrates to the valuable product produced from both Nickel Rim and Fraser (mines),” Côté said.
Once economic viability has been determined, Xstrata will start applying for permits, begin the environmental assessment process, and start conducting community consultations. Côté said the company estimates construction could start by 2014 and the facility could be ready for production by 2016.
Côté said the concentrate produced from the Errington-Vermilion project will help replace some of the volume lost following the recent shutdown of Brunswick Mine, located in Bathurst, NB, which was formerly its biggest zinc producer.