HudBay Minerals Future Bright, Even Without Copper Smelter

The closing of HudBay Minerals’ 80-year-old copper smelter next summer will mark the end of an era in Flin Flon. The plant has fallen victim to old, inefficient technology and a shortage of concentrate feed. Yet the company’s future is looking bright with new mines on the horizon and the continued operation of the concentrator and the modern zinc refinery.

The decision to close the Flin Flon smelter, along with HudBay’s White Pine copper refinery in Michigan, was announced in mid-June and gave a July 1, 2010 deadline for the smelter shutdown. Approximately 225 jobs will be lost in Flin Flon and another 65 when the refinery closes shortly after the smelter. The Flin Flon concentrator and zinc refinery will continue to operate.

The smelter has an annual capacity of 90,000 tonnes of copper anode, but in 2008 the smelter produced only 82,458 tonnes. About 60% of the output comes from copper concentrates mined and processed by HudBay. The remainder of the copper came from purchased concentrates (32%) and spent anodes (9.5%) from the White Pine refinery.

The greatest benefit of closing the smelter is that particulate and sulphur dioxide emissions will be essentially eliminated. With no airborne pollutants, Flin Flon will become one of the most environmentally friendly integrated metals facilities in North America.

Rather than being smelted in Manitoba, concentrates will be shipped to other as-yet-unnamed smelters. HudBay will install a Larox copper concentrate filtration plant to reduce the amount of moisture to 8% before shipment.

Current operations

HudBay operates two mines near Flin Flon, its flagship 777 mine that began production in 2004 and the older Trout Lake mine that began production in 1982.

The 777 mine produces 4,000 t/d of ore using predominately longhole open stoping with a primary and secondary sequence employing cemented paste backfill in the primary stopes and development waste in the secondary stopes. Reserves as of Jan. 1, 2009 were 14.4 million tonnes grading 2.45% Cu, 4.62% Zn, 2.30 g/t Au and 29.22 g/t Ag.

Ore is recovered from the Trout Lake mine by predominantly longhole open stoping, and the development waste is used as backfill. In narrow zones longitudinal retreat has also been practised. Major development is going in the Deep West zone and will average 4,000 to 5,000 m/y. At Jan. 1, 2009, Trout Lake reserves stood at 1.7 million tonnes grading 2.07% Cu, 3.58% Zn, 1.47 g/t Au and 11.31 g/t Ag.

Ore from both mines is trucked in the Flin Flon concentrator. It will treat about 2.2 million tonnes of ore to produce 185,000 tonnes of copper concentrate and 159,000 tonnes of zinc concentrate in 2009.

Run-of-mine ore is reduced to 20-mm in a two-stage closed circuit plant. The ore goes to the grinding circuit (two rod mills in open circuit and a single ball mill in closed circuit with cyclones) and is further reduced to 80% passing 70 microns.

Copper and zinc are recovered in sequential flotation circuits. The copper circuit consists of roughing, scavenging and two-stage cleaning. Tailings from the copper circuit are conditioned and passed through the zinc circuit consisting of roughing, scavenging and three-stage cleaning. Individual concentrate grades are 24.5% Cu and 51% Zn.

The new zinc refinery at Flin Flon is the world’s first two-stage pressure leaching facility. It treated 208,000 tonnes of zinc concentrate in 2008.

Exciting future

Senior VP operations Tom Goodman spoke enthusiastically with CMJ about the potential of the Lalor deposit to become HudBay’s next major producer in Manitoba.

“It’s going to be a big part of our future. We believe it will be an exciting zinc mine, the high-grade gold zones make it even more exiting. It’s going to be a good one,” he promised.

Discovered in 2007, Lalor is a massive sulphide deposit similar to the nearby suspended Chisel North mine and only 15 km from the Snow Lake concentrator. When the discovery was announced, HudBay said it had the potential to contain between 18 million and 20 million tonnes of material at 7.7% and 8.8% Zn. The discovery of gold mineralization, which assayed as high as 32.89 g/t Au from one part of the hanging wall, only makes the project much more interesting.

The most recent resource estimate for the Lalor deposit has 3.4 million tonnes grading 1.9 g/t Au, 20.5 g/t Ag, 0.71% Cu and 8.82% Zn in the indicated category. The inferred material totals 13.2 million tonnes grading 2.9 g/t Au, 32.1 g/t Ag, 0.70% Cu and 8.19% Zn. Those numbers are a couple years old and undoubtedly will grow when a new 43-101 report is compiled.

The Lalor project is now in the study stage, said Goodman. All the options are being examined. For instance, the Snow Lake concentrator might be revamped to handle the gold in the ore or a new gold recovery plant might be accessed or built.

Nor is Lalor the only exciting discovery in the Flin Flon Greenstone Belt. HudBay considers the Belt to be underexplored, and there are several potential projects -Jazz, Burr, Pen 2, Watts River, Talbot Lake, Grassberry, Harmin. Watch for these names in the future.

“We are very positive about the future of our Manitoba operations,” said Goodman. “First and foremost we have a long history of success to build upon with a very capable and experienced workforce. We have our flagship 777 mine, great processing plants in Flin Flon, including our state of the art zinc pressure leaching plant and new zinc refinery along with our recently refurbished concentrator. At Snow Lake we are well positioned with our advancing Lalor project along with our existing Snow Lake concentrator.”

With plants, people and new mines, HudBay’s future in the province is certainly secure.