New optics for northern Abitibi
The only decoration in the general manager’s office at the Langlois mine is a black and white photo of a suited man. The zinc mine and mill, 213 km northeast of Val d’Or in northwest Quebec, was named after the man in the photo, L. Gonzague Langlois, former head of the Quebec Mining Association, when the mine was started up by Montreal-based Cambior Inc. in 1996.
From the start, ground problems limited the amount of ore that could be produced. With zinc prices down around US$0.40/lb, Cambior sold Langlois and the surrounding properties to Breakwater Resources Ltd. of Toronto on May 1, 2000, for US$19.8 million. The new owner suspended operations in late November.
Since then, additional discoveries of high grade ore, operational improvements at relatively small capital costs, high zinc recovery and favourable metal markets have come together to make Langlois a successful turnaround story.
A full feasibility study was issued in 2001, and was updated in 2003 and 2005 by SRK Consulting. With the zinc price rising above US$0.80/lb, Breakwater announced its plans at the end of 2005 to redevelop the mine and adjacent Zone 97.
After a 15-month flurry of activity and $62.3 million in capital spending, Langlois achieved commercial production on July 1. At today’s zinc prices of US$1.45/lb, Langlois is expected to be profitable by September 2007. Another $16.7 million in capital costs are anticipated to the end of this year.
The operation plans to mine 394,000 tonnes (t) of ore grading 9.0% Zn and 0.5% Cu this year, to produce 62.4 million lb of payable zinc, 2.9 million lb of payable copper and 121,000 oz of payable silver.
The mine has come along at the right time for the region as the local forestry industry is downsizing. More than half of Langlois’ 135 employees live in the 3,500-person town of Lebel-sur-Quvillon, 48 km to the southwest. Breakwater’s workforce should grow to more than 200 by year end. A six-year agreement with the United Steelworkers local at Langlois was renewed last year.
Langlois becomes Breakwater’s fourth 100%-owned operating zinc mine, joining Myra Falls in British Columbia, El Mochito in Honduras, and El Toqui in southern Chile. As well Breakwater owns three zinc mines that are now closed–Bougrine in Tunisia, Bouchard-Hbert in Quebec and Nanisivik in Nunavut.
The Langlois mine in the northern Abitibi belt consists of stacked, subvertical, tabular VMS bodies in highly deformed Archean volcanic rocks, injected by barren mafic dikes. The high grade sphalerite/pyrite-rich bodies have considerable lateral and vertical extent, varying in width from less than one metre to eight metres.
Zones 3 and 4 are under production. One kilometre east of the shaft and starting 200 m below surface is Zone 97, discovered in 1994 but only recently well defined. Zone 97 is being developed for production starting in early 2008. Lower grade Zone 5 is being explored near surface, 150 m south of Zone 3.
At year-end 2006, Langlois had proven and probable reserves of 3.6 million t grading 10.1% Zn, 0.8% Cu, 49 g/t Ag and 0.1 g/t Au. As well there are measured and indicated resources of 2.0 million t at similar grades, and 1.8 million t of inferred resources at slightly lower grades.
The mine is served by a 902-m-deep, four-compartment shaft with two hoists, one for skipping and the other for services. The mine has been developed on 4, 6, 9, 10, 11, 13 and 15 levels; shaft bottom is at level 17.
The original mining method used in 1996–transverse longhole stoping, with 60-m-tall mining blocks and 114-mm-diameter ITH production holes–resulted in crumbling walls, excessive dilution, and an ore pass system that collapsed and was eventually condemned. Langlois has since backfilled the former ore pass; this has been replaced by fully automated ore handling facilities near the shaft on levels 9 and 11, and one that is being built on level 13. The waste pass system is still used, with waste skipped from level 16 to surface.
Mining at Langlois today has reduced the block sizes to 20 m high by 20 m long (15 m between sublevels), and reduced production holes to 54-mm diameter to minimize blast damage. Where the mineralization is wider than three metres, ramp-accessed sublevels were previously developed at 30 m apart; drilling is with 102-mm-diameter drill holes and 75-mm casings inserted into the holes. Blasting with Anfo is centrally controlled. Muck is retrieved by load-haul-dump machines (most of them remotely controlled) and hauled by LHD or truck to one of the ore handling facilities.
The main ventilation raise supplies 6,200 m3/min of fresh air to the mine; exhaust air exits through the Zone 3 ventilation raise, the main production shaft or a raise borehole in Zone 97.
The current management team members, who have arrived at Langlois within the last year, include general manager Jean-Luc Chouinard, chief geologist Donald Gervais, chief mine engineer Daniel Ct, mine superintendent Marc Desfosss, mine captain Guy Lapointe, mill superintendent Norman Kock, Faek Latrash who manages maintenance, and controller Richard Dubuc.
Their initial decision was to add more flexibility to the mine plan by adding other underground accesses and opening up more mining areas. A new ramp was collared this January very close to the headframe, which will free up shaft capacity for skipping and open up near-surface Zone 4 ore to be mined. That ramp is now in the top of Zone 4, and may reach level 9 by next spring.
Contractor Ross Finlay is handling the development of Zone 97: drifting across from the shaft on levels 9 and 13, and driving a decline between level 9 and 13. A ramp from level 4 will reach Zone 97 on level 6. Later on, an internal ramp will be built from level 6 to 13.
The mine has doubled its underground mobile equipment fleet to over 100 pieces, including Toro 35-t trucks, Toro 450D and 500D 4.6-m3 LHDs and a fleet of EJC130 scoops.
The focus has shifted from ore production to pastefill at Langlois, to control the jointed, schistose rock. Stopes are backfilled as soon as they are mined out, greatly reducing dilution and ground problems. All backs and walls of the drifts and cross-cuts are screened with wire mesh. The walls are bolted with 1.5-m-long Split Set bolts; 2.1-m-long rebars are placed in the back, with resin bolts to resist corrosion.
The mill crews have a running joke that someday the mine will flood the 2,570-t/day mill with ore. So far, the opposite has been true. While the mine works 24/7, the mill currently operates just 5.5 days per week, 2,200 t/day–essentially 70% of capacity.
The plant produces zinc and copper concentrates by differential flotation. A crew of 30 works on three 12-hour shifts, with one operator overseeing each of flotation, grinding, backfill and filtration. Mill superintendent Norman Kock describes Langlois as “the nicest mill in the Abitibi”. The spacious, fully automated concentrator was designed by Cambior as state of the art, and was well taken care of during the shutdown, until it started up in November 2006.
Zinc concentrate, which is the main product, contains 52.8% Zn and less than 9.5% Fe.
Langlois achieved a remarkable 92% zinc recovery from May-July 2007, slightly below the budgeted 93.5%, but “much higher than what everyone else is getting,” says Kock, and should hit budget by year-end. Contributing to the high recovery is the choice of reagents (especially 3418-A in the copper circuit and 507B in the rougher and cleaner section of the zinc circuit) and the degree of computer control and online sampling. The Factory Link software has been updated to improve performance. Fourteen points on the circuit (there will soon be 16) are sampled every two to three minutes by the Boliden onstream x-ray analyzer for copper, zinc and iron content.
The copper and zinc thickener underflows are batch filtered in the Schriver filter press to 7-8% moisture, and loaded into 16-28 CN gondola rail cars
(82-dry-tonne-capacity) for shipment twice a week. Zinc concentrate is currently sold to Xstrata’s CEZ smelter in Valleyfield, Que., its Kidd Creek smelter in Timmins, Ont., or to Hudbay’s smelter in Flin Flon, Man. Copper concentrate is railed to Xstrata’s Horne smelter in Rouyn-Noranda, Que.
Over 60% of the final tails are thickened and disc-filtered in the pastefill plant to 85% solids, mixed with cement and pumped to a holding tank. The slurry descends by gravity into stopes in Zone 3. Two pumps installed by the end of 2007 will deliver pastefill to Zones 4 and 97 via insulated lines.
The rest of the tails are pumped to the 91.88-km2 impoundment area three kilometres away for subaqueous discharge. Mine water is pumped via the plant to the impoundment area, for re-use in the plant. The impoundment can hold the tails from the mine’s total current resources.
Acid-generating rock, if there is any, will be placed underground as part of the $1.7-million reclamation plan, and the rest will eventually be deposited underwater in the impoundment area.
Work continues on a long list of projects to modernize, upgrade, improve and expand. The mine is scrambling to prepare enough stopes to feed the mill, which intends to operate seven days per week by November, and then move toward its full capacity in 2008. To that end, a fourth ore handling facility may be added on level 4 of the mine. The skip capacity will be increased from six to eight tonnes, and the capacity of the hoist motors increased slightly to 745 kW.
A Larox filter press will be added to keep zinc and copper dewatering separate, and eventually the concentrate will be shipped out three times per week. A lead circuit may be added in the plant later on.
Breakwater’s exploration team is conducting aggressive exploration on its 10,245-ha landholdings in the area. The 2007 drill program is focusing on EM anomalies identified by down-hole geophysics. A GOCAD model is being built including the Breakwater lands plus 3,402 ha of property held in 50/50 joint venture with Montreal-based Metco Resources, extending over more than 27 km. This includes the Orphe deposit (six kilometres east of the Langlois mill), for which Metco plans to release a prefeasibility study this fall.
Breakwater’s most advanced project is Grevet B, 3.2 km northeast of the Langlois shaft, where a 15,000-tonne bulk sample was taken via a ramp begun last year.
The troubled Langlois mine of the past has become a company-maker for Breakwater. General manager Chouinard believes its current eight- to 10-year life could extend to more than two decades, making Langlois the centre of a new mine camp in Quebec.