SOMBA K'E/YELLOWKNIFE
Those fighting to save the Robertson Headframe from being reduced to a pile of rubble often invoke the importance of the old elevator shaft as a monument to Yellowknife's mining history.

The Robertson Headframe under construction in the late 1970s. Work on the shaft underneath the 249-foot steel headframe began in 1973 and was completed in 1977. - photo courtesy of Ryan Silke/NWT Mining Heritage Society

Without any other prominent structures punctuating the city's skyline, there is no question the headframe has become a de facto landmark for those who call Yellowknife home.

But how did the 249-foot steel behemoth come to dominate the landscape?

The headframe's foundations can be traced back to the mid-1930s when prospectors flocked to Yellowknife in anticipation of a gold boom. The speculation of those early trailblazers was ultimately validated when Con Mine began operation in the fall of 1938, thereby becoming the first gold-producing mine in the Northwest Territories. Despite closing for a few years in the mid-1940s, the mine went on to prosper as immigrants travelled from around the world to toil deep beneath the grey and pink granite of the Canadian Shield.

But by the 1960s, dropping gold prices meant shareholders were getting a diminished return on their investment, according to local historian Ryan Silke.

"For most of the of the 1960s, Con was operating at a very marginal level in terms of profitability and the reason for that was the price of gold was very static. It hadn't changed in basically 30 years," said Silke.

The fact that the mine was using a system of two shafts in order to bring ore up to the surface also meant mine's operating costs were going up while the yield of gold was going down.

The two-shaft system comprised the original C1 shaft and went straight down to a depth of 2,000 feet. It was later complemented by the addition of an angled, horizontal shaft that was 8,000 feet long and extended the total depth of the mine to 4,900 feet. The horizontal shaft had arteries extending into the ore body on either side of it.

While the elaborate system allowed the mine to expand its exploration, it made for a highly inefficient operation.

"Every time they mucked out ore, they had to tram it, then dump into the hoist, then hoist it, then dump it, then take it from that hoist to a tram, and then dump into a hoist and bring it to the surface," said Silke.

"You had a bottleneck where the lower levels couldn't produce enough ore to bring up to the surface that would be economic."

With the price of gold was at a pitiful $35 an ounce, the mine was unable to spend money on improving the system, said Silke.

Then in 1971, the mine's fortunes changed. The gold standard for currency was dropped, causing the value to skyrocket to more than $100 an ounce in a matter of a few years.

The resulting jump in the price of gold provided then mine owner Cominco with an incentive to expand exploration and invest in new infrastructure, said Silke.

"That was the idea behind the Robertson Shaft - to sink a new shaft from the surface down to 5,000 feet to access those ore zones and basically eliminate that old network of shafts, which had become antiquated," he said.

Work on the new shaft began 1973. Four years and $20 million later, the headframe and the 5,400 foot shaft beneath it were complete.

The design for the Robertson Headframe - named after Con Mine foreman Bob Robertson - was modeled on a German design which was popular in South Africa during the 1970s.

"The manager in charge of the mine in the 1970s had worked in South Africa, so he basically applied a lot of the technology that was there at Con," said Silke.

What made Robertson Headframe so unique in comparison to other headframes in the North is its elevator system, operated by a "friction hoist." The friction hoist functioned by suspending cables for the skip - a lift used to hoist ore - on either side of a big drum, where they were looped around in order to counterbalance the cage - used for hoisting men. As such, when one lift was at the top, the other would be at the bottom. Although the drum was powered, the force of gravity transferred by the weight of the ropes on the drum helped spin the wheel.

Bill Higden spent 12 years working underground as an electrician and many more above ground at Con Mine.

Higden said the hoist could travel up to 1,400 feet per minute. He described the ride as being on "a freight train coming up vertically."

According to Silke, the inch-and-a-half wide steel cables totalled 15 km in length and weighed 120 tonnes. The enormous length of the cables are the reason the headframe was so massive.

"The ropes not only had to support the conveyances, but they also had to support the weight of themselves ... and the headframe, of course, had to support the weight of it all," he said.

With the previous system of shafts and trolleys, a maximum of 10 men could travel to depths of the mine at once and their commute could take as long as 45 minutes, Silke said. In comparison, the new elevator shaft could take 64 miners from the surface down to the bottom in five minutes.

"The shaft re-invented underground mining at Con," Silke said.

As efficiency at the mine improved and the price of gold remained high, the mine continued to thrive.

In 1985, the shaft was increased to its final depth of 6,240 feet. Later that year the mine was bought by Nerco Minerals Ltd., before being sold to its last owner, Miramar Mining Corporation, in 1993.

By the late 1990s, the mine was becoming less profitable as gold underneath the mine began to run out while the price of gold went down.

"Every mine has its life and by that time Con was coming to its end," said Silke.

On November 28, 2003, miners took their last ride up from the depths of the Robertson shaft as the mine closed down for good.

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