Uranium Mine Reclamation Case Study

In 1953, the discovery of uranium in the Algoma basin in Ontario, Canada, led to the development of the largest uranium field in the world. By 1957 the confirmed uranium ore reserves at Elliot Lake, Ontario, were greater than the total of all 600 plus uranium mines in the USA. Full scale development of the ore body started in 1957 with approximately 25,000 people living in the town of Elliot Lake during the boom years of the early 1960's. Since that period, the supply of uranium has outpaced demand, and the mine's output dropped. By the 1990's, the cost to mine uranium in the Elliot Lake area was not competitive with world uranium prices. As a result, one of the major mining companies in the region, Denison Mines Ltd., closed its Elliot Lake mines.

In order to ensure that the remains of the mining operation were left in an environmentally responsible condition, Denison made a decision to place all of the mine tailings under a permanent water cover. Mine tailings are generally a fine/course (50% +200 mesh) white quartz sand from the mining process containing some 5% pyrite, which generates acid when left exposed to the atmosphere. Putting tailings under a water cover stops the acid generation. The final configuration for these tailings as a permanent close-out option will be determined by a federally administered public review. The tailings were located in the Long Lake tailings basin which is approximately 3 km long and 1.2 km wide and which contained several million cubic yards of tailings.

Denison Mines awarded a dredging contract to Auburn Industrial Services Ltd., of Sudbury, Ontario, to relocate the tailings. The objective was to get all tailings underwater and to provide additional stability to the western headpond dams by pumping the coarse tailings from the east end of the lake to the west end.

Auburn investigated several types of dredges and various dredge manufacturers before selecting the Mud Cat™ Division of Ellicott International. The Series 370 dredge was selected because it was highly portable and had a minimum draft of 36". The Series 370 can be transported completely assembled on a singled trailer. This was important due to difficult accessibility to the site. Only a single crane is needed to lift the 25 ton dredging machine into the lake. The dredge, while being very compact, is very powerful and can achieve the high production rates required. In fact a Series 370 dredge and one booster station pumped high concentrations of solids approximately 2.5 km. Ellicott was able to offer flexible purchase terms, huge spare parts availability and operator training on site. All of the above advantages plus the immediate availability of the dredges from inventory made Auburn's decision easy.

Mr. D. A. Sandy McKinty, Vice President of Contract Operations for Auburn, has been very pleased with the performance of the 370 dredges and boosters and credits the involvement of all Ellicott personnel in the overall success of the project.

Over 50 Ellicott Series 370 "DRAGON™" dredges are in operation in North and South America, Europe, Africa, and Asia.

For more information, please contact the Mud Cat™ Division of Ellicott International.

Mud Cat™ Division of Ellicott International