Osisko Mining Corp. reported that the Canadian Malartic mill returned to full operational status May 19, 2012. This follows the earlier reported May 9 fire and completion of temporary repairs to the damaged No. 4 cyclone set.

The mill resumed partial operation May 16, with the grinding circuit using three of the four cyclone sets and two of the three ball mills, as well as the semi-autogenous grinding (SAG) unit. Completion of temporary repairs to the fourth cyclone circuit and the completion of scheduled maintenance on the primary and secondary crushers allowed for the resumption of full production.

“We are very proud of the speedy effort our team has made in getting the mill up and returned to operation after the fire,” said Sean Roosen, president and CEO, Osisko. “We greatly appreciate the outstanding efforts of our employees, contractors and suppliers. We’d particularly like to thank Guay Inc. for getting their large capacity crane to site so quickly which allowed us to remove the damaged equipment and commence repairs; Rematech Inc. for supplying site assistance and shop availability for the rubber pipe repair and cyclopack refurbishing; and FLSmidth Krebs for the very fast cyclone refurbishing in their shop. All of these suppliers gave us 24 hours per day assistance and relly made a great difference in the speed of our recovery from the fire. The location of the Canadian Malartic mine has allowed us to respond quickly to the challenges and really gave us rapid access to the necessary expertise and support infrastructure.”

Production rates are still at ramp-up levels but have now returned to the pre-fire range. Modifications to the XL2000 cone crusher bowl and liners have been effected under recommendations and supervision from the supplier (FLSmidth). Their representatives are currently on site monitoring and adjusting the crusher circuit while trials of the modifications are conducted. Current throughputs during this work are expected to range between 35,000- 40,000 metric tons per day (mt/d). Pending successful completion of this work, Osisko expects to see the circuit stabilize in the 40,000-45,000 mt/d range as the company awaits the arrival and installation of the second XL2000 cone crusher.

The second XL2000 (No. 2 of two cone crushers comprising the secondary crusher) is currently expected to be installed and operational by July. This should allow the circuit to subsequently increase throughput to 50,000-55,000 mt/d. Further optimization to the circuit, including the installation in August of the previously announced second pebble crusher, is expected to lead to increased daily throughput by September.

“We are continuing to ramp up production, make modifications to improve throughput and stabilize the circuit,” said Luc Lessard, senior vice president and COO, Osisko. “During the unplanned stoppage, we accelerated the regular maintenance of key operating units, which should improve our near term performance as we gain better plant availability.”

Equipment and building damage from the fire is estimated between $6 and $8 million. The company is working with its insurance underwriters and adjusters and expects the costs of the physical damages to be fully covered subject to a $250,000 deductible. Permanent repairs of the damage will continue over the next three to four months, with the eventual replacement of the No. 4 cyclone set with a new cyclone cluster currently being manufactured by the supplier. Repairs to the damaged overhead crane and the mill roof will also be completed during this period. Minimal impact on production during these final repairs is anticipated.