have certain regulated permit caps on the amount of seismic motion that we can create within the earth,” Poulson said. “We want to keep it well below that, so we’re in permit—but most importantly so that we minimize the seismic impact to our neighbors.”
The explosion will turn the rock into rubble that is five feet in size or less, which is what is needed to fit into the mine’s crusher. The rubble, or “shot muck,” is shoveled into the back of the mining trucks. A digital readout on the side tells how many tons they’re carrying. Poulson said the area’s original miners were digging out gold from veins or removing high-grade ore. What the Cripple Creek & Victor Gold Mine is hauling to their crusher is disseminated ore. It takes many tons of disseminated ore to get an ounce of gold.
“That’s why we have to move so much of it to make it economic,” Poulson said. Every year sixty million tons of rock is moved, which includes twenty million tons of ore, and forty million tons of overburden, or waste rock.
A Vug of Gold
We got back in the company truck and headed out of the Wild Horse extension surface mine to see one of the other, larger mines. Poulson slowed down as we pulled in behind one of the massive haul trucks.
“You never pass a haul truck without permission and if it is moving you don’t even ask for permission, you just get in line,” he said. “Haul trucks have the right of way.” It’s easy to see why. Anything the size of a multistory house with wheels that belong on a monster truck is going to win a game of chicken every time. Poulson told me the area was historically so rich in gold that the miners could dig out large veins of gold, sometimes as big as five feet wide. In 1914, a miner discovered a “vug,” or giant pocket, of gold in the area. It yielded sixty thousand ounces of gold.
The Cripple Creek & Victor Gold Mine’s Cresson Surface Mine. (Courtesy of CC&V)
“The vug of gold disclosed the beauty of an Aladdin’s cave and the wealth of the United States Mint,” reported a 1918 edition of The Mining American. It wasn’t the last vug of gold discovered in the area.
“Thirty-eight coming up the Joe Dandy, in the wrong way, and going around the blade,” the radio chirped incomprehensibly, taking me from thoughts of massive caves filled with gold. Poulson said the mine’s exploration geologists work to create three-dimensional underground images to get an idea of what lies beneath the surface.
“An engineer can apply very sophisticated tools to determine the cost inputs, versus the revenue inputs, from the ore body that is being mined,” Poulson explained. “Ultimately that determines the shape of the surface mine.”
The Cripple Creek & Victor Gold Mine currently has two surface mines in operation and a third and fourth in the process of being opened. The 1,200-foot-deep Cresson surface mine shows scars along its steps of the 100-year-old mines that came before. Today’s miners often come across and have to backfill those original mine shafts and tunnels.
“The old-timers went much deeper than where we are,” Poulson said.
A LIDAR unit, which stands for Light Detection and Ranging, uses lasers like a radar uses sound. The mine uses the lasers and a slope radar to measure and draw a picture of the mine’s wall to help determine if there’s going to be a collapse. There are also old mine stopes, or underground empty spaces where ore was once extracted, large enough to swallow one of the big trucks. Poulson said the mine is constantly monitoring and keeping track of where historic mining activity took place and where voids might appear.
“We have historic mapping, that is now computerized … and then all of our exploration and blast hole drilling is logged with GPSs and they find voids,” Poulson explained. When voids are found they are logged, mapped, blasted, and filled with rock by remote controlled vehicles to keep the miners out of danger.
“We’re not bragging—but modern mining is safe because we maintain a safety focus,” Poulson said.
“Pregnant with Gold and Silver”
The ore is transported to a crusher for processing. Crushers grind the stone like a massive mortar and pestle. The mine’s primary crusher works through seventy thousand tons of ore a day, and twenty million tons a year. The ore then goes past an electromagnet that pulls out old lunch buckets, ore tracks, lamps, or anything metallic that doesn’t belong. It then goes on a conveyor belt where it is sorted into different sizes or sent back to another crusher. There are a series of conveyor belt tracks that look like the highest, most unpleasant roller coaster in the world.
Lime is mixed in with the crushed ore to keep from evaporating the process solution’s sodium cyanide, used to leach the gold and silver out of the ore. The crushed ore is stacked in these gray hills, and the solution is dripped out onto them. Since the early ’90s, four hundred million tons of crushed ore have been collected in this part of the property. The gold and silver dissolves in the diluted mixture of sodium cyanide in water and flows down with the solution to self-contained underground ponds or wells. Poulson said none of the fluid escapes this double- and in some areas triple-lined facility, and the solution is recycled back through the process after the gold and silver are removed.
“The gold and silver is more attracted to the diluted mixture of sodium cyanide in the water than it is to the elements in the rock,” he said. “So the gold and silver leave the ore and attaches to the sodium cyanide and the process solution becomes pregnant with gold and silver.”
That gold- and silver-rich solution is then pumped to another facility where the minerals are removed from the solution and put into a furnace. The melted metals are poured into “button” molds that weigh about sixty pounds and consists of about 63 percent gold, 30 percent silver, and some impurities ranging from copper to iron. It is then sent to another facility out of state where the metals are further refined.
“Last year we produced about 190,000 ounces of gold and about 60,000 ounces of silver,” Poulson said, driving alongside the leaching pads. “Next year we’re estimating over 350,000 ounces of gold because of our investment in new process facilities.”
That gold is sold into the market. Gold can be used for bullion, jewelry, or a reserve currency for governments; as an investment; and in the high-tech manufacture of smartphones, avionics, and satellites.
Builders of high-rises use gold in glass to reinforce it and to filter out radiation. Colorado’s only commercial gold mining operation is growing and has plans for expanding and may one day even consider plans for more traditional underground mining operations.
The gold will eventually become depleted from the area. This inevitability comes to all mines and across all eras. Strict regulations on modern mining will also require the company to reclaim the area and match the surrounding geography and ecology.
But the search will continue as it has since antiquity and the Cripple Creek & Victor Gold Mine is not alone in looking for gold in Colorado.
Across the state, and in the historic mining districts, there are people picking up gold pans and prospecting supplies for the first time. And then there are those who have hunted for gold their whole lives.
CHASING
