International Dredging Review

International Dredging Review
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Eddy Pump Corporation has a star. The company’s new dredge called the Subdredge is a featured player in two seasons of “Bering Sea Gold” on the Discovery Channel.

The first season with the Subdredge featuring winter mining beneath five feet of sea ice broadcast in September and October. The second season featuring underwater mining during spring and summer will broadcast in 2016.

“Bering Sea Gold” follows underwater miners off of Nome Alaska as they battle choppy seas poor underwater visibility equipment failures and other challenges to mine for gold in shallow waters of the Bering Sea.

A typical mining rig supports a dredge a sluicing apparatus to separate gold particles from sand and debris and a life support system for the divers who operate the dredge under water. Because of safety issues associated with human diving they generally operate at depths of no more than 25 feet.

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A new dredge built by Eddy Pump Corp. prepared to mine for gold in the Bering Sea off Nome Alaska.

The Subdredge is dramatically different from the dredges that miners previously utilized. It is a remotely operated submersible dredge and can operate at depths exceeding 125 feet while being safely controlled by an operator on the surface. When equipped with high-powered lights cameras and acoustic positioning an operator can maneuver and operate the dredge with as much accuracy as a diver.

At the core of the dredge is a four-inch heavy duty Eddy Pump which uses the principles of a tornado to create a synchronized eddy current to displace material on the seabed. “It is a swirling current of water that forces solids up the sides of the hose” said Eddy Pump spokesman Ben Weinrib. “It pumps a higher volume of solids with less water” he said.

Weinrib said the Eddy Pump “is the most highly efficient high solids and high specific gravity pump on the market” and because it has no critical tolerance parts it requires less maintenance and experiences less down time than other pumps.

Remote operation is one key to the efficiency of Eddy Pump’s submersible dredges he said and it made a huge difference in Alaska. Previously mining the seabed for gold particles was a warm weather activity because it required open water. Since it is operated remotely however the Subdredge was able to work in the winter.

The four-inch compact submersible tracked dredge is rated to pump up to 900 gallons of slurry per minute and powered hydraulically.

The submersible’s equipment includes depth pressure and orientation sensors a handheld wireless controller and live redundant controller and pneumatic lift bags for emergency retrieval.

The sub is 172 inches long 62 inches wide and 60 inches tall and weighs 4800 pounds. It has an umbilical length of 312 feet and in the Bering Sea can operate at depths up to 200 feet while pumping up to 125-cubic-yards of material an hour. They used both cutterhead and non-clog head configurations.

The Subdredge “is the first remote operated gold mining mini-dredge” Weinrib said. “It outperformed everyone’s expectations” outproducing diver-assisted dredging by a factor of 10. The dredge was averaging three ounces of gold per hour and won the gold count on the show he said.

The 25-year-old Eddy Pump Corporation originally developed submersible dredges for irrigation districts and power plants. Remote operation reduces the costs of operation mobilization and demobilization he said.

For more on Alaska’s offshore gold mining leases see “Pacifica and Art Anderson Build Dredge for Alaskan Gold Lease” IDR January/February 2013.