New start for New Afton
Usually, when someone utters the phrase, “There are a lot of moving parts,” it’s for effect.
Not so when those words are coming out of Craig Lockhart’s mouth.
The mill manager at New Gold’s New Afton Mine, Lockhart is responsible for overseeing the plant in which raw ore is refined into something of value — something known in the industry as “concentrate.”
He was there when the mill was fired up for the first time on June 28 and he was there seven days later — Thursday, July 5 — when the mine’s first 50-ton truckload of concentrate was shipped out to buyers.
And, Lockhart said, to say things have been running smoothly since production began would be an understatement.
“From the day we just mashed that button until today, we’ve seen uncommonly few mistakes,” he told KTW.
“With a circuit as complex as it is, with that many moving parts, we haven’t put many holes in anything yet.
“The whole circuit is working together very well and it’s doing what it’s supposed to do very well.”
For a milling process involving so many abrasive steps and so much brute force, Lockhart said, that’s an impressive feat.
The process New Gold is following to turn New Afton dirt into copper and gold is a complicated one.
The mine is an underground block-cave operation, with four kilometres of tunnels underneath Teck’s old open-pit Afton site.
The raw ore is extracted through a process of drilling out earth from above the tunnels and collecting the material after it falls.
From there, a series of conveyor belts takes the ore back up to the surface — coming out just west of the old Afton pit.
The ore — made up of one per cent copper and 0.6 parts per million gold — then goes to a large stockpile adjacent to the pit before being pulled by conveyor belt into the mill itself.
Today, the mill is taking in about 350 tons per hour. That number will jump to 450 tons per hour by the time New Afton is in full production.
Upon entering the mill, the ore is dumped into a large processor in which it’s rattled around alongside hundreds of five-inch steel balls.
From there, it is screened and sent to a second, smaller processor containing three-inch steel balls.
A third processor — keeping with the theme — contains one-inch steel balls.
After that, the material is sent into a series of float cells — large vats containing water and a mix of chemicals to further separate the valuables from the dirt.
The finished concentrate is then dumped into a storage pile to be trucked off to Vancouver and, eventually, shipped overseas.
By the time the ore has been processed, the amount of copper in the concentrate is in the 28 per cent neighbourhood. It also contains 20 to 30 grams per ton of gold.
Lockhart said the turnaround time for a particular piece of ore can be anywhere between 60 minutes and 24 hours.
“We’re dealing with nature and we’re dealing with minerals,” he said.
“Some of it’s going to flow and some of it’s not.”
Mine officials expect to be at commercial production levels — 60 per cent capacity — by August and full production later this year.
Lockhart said New Afton management is happy with the early results of the operation.
“We’re certainly pretty pleased,” he said.
“If you look at start-ups around the world, we’re keeping up with some of the best.”
NEW AFTON BY THE NUMBERS
The number of employees at the New Afton mine site — 488 staff and 393 contractors.
Days between the first cave blast at the site (June 27, 2011) and the start of production in New Afton’s mill (June 28, 2012).
The percentage of New Gold’s New Afton employees who are of First Nations heritage.
The year mining giant Teck — operator of the Highland Valley Copper Mine near Logan Lake — shut down its open-pit operation at Afton, following a 20-year run. The old Teck mill still stands on the New Afton site, but it was deemed obsolete and is slated for demolition. New Gold staff have renovated Teck’s old on-site office building and use it for their own administration.
The century in which mining on the site began, albeit at a much more modest scale.
The number, in millions, of litres pumped out of Kamloops Lake in 2011 for use at the New Afton site.
The number of members on the New Afton emergency mines rescue team, trained to use extrication equipment, breathing apparatuses, spill clean-up gear and fire-suppression tools.
The emergency mines rescue team’s finish at the 2011 B.C. Mine Rescue Provincial Championships, held in Revelstoke.
The number of fire engines for the New Afton emergency mines rescue team.