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Exploration &

McClean Lake

McClean Lake is comprised of several uranium deposits and a conventional mill and is located on the eastern edge of the Athabasca Basin in northern Saskatchewan approximately 26 kilometres west of the Rabbit Lake mine and approximately 750 kilometres north of Saskatoon. The project includes the JEB, McClean, Sue, and Caribou deposits several exploration prospects. Development of the McClean Lake project began in March 1995. Construction and commissioning were completed in 1997. The McClean Lake mill began production of uranium concentrates in 1999, processing ore from the JEB deposit. The first ore was fed to the mill on June 22, 1999 and commercial production was achieved on November 1, 1999. To date, the McClean Lake mill has produced approximately 49.9 million pounds U3O8. The mill is currently on care and maintenance since 2010.

McClean Lake Project is a joint venture between AREVA Resources Canada Inc. (70%), Denison Mines Corp. (22.5%) and OURD (Canada) Ltd. (7.5%). AREVA is the mining and exploration operator.

Access to the property is by all-weather gravel road (Highway 102 and 905) from La Ronge to the McClean Lake mine site, about 35 kilometres east of Points North Landing. Most of the project area is accessible by all-weather road or winter trails. Regularly scheduled air service exists between Saskatoon and Points North Landing, provided by commercial airlines and air charter service for the McClean Lake mine site.

McClean Lake Mill

The McClean Lake mill uses sulphuric acid and hydrogen peroxide leaching and a solvent extraction recovery process to extract and recover the uranium product from the ore. In addition to the mill facility, other infrastructure on the site includes a sulphuric acid plant, a ferric sulphate plant, an oxygen plant, warehouses, shops, offices and living accommodations for site personnel. The facilities are currently being expanded from a capacity of 13.0 million pounds U3O8 per year to approximately 24.0 million pounds per year to permit the processing of ore from the nearby Cigar Lake mine operated by Cameco Corporation, which is anticipated to begin mid-2014. Construction of the expansion is expected to be completed by 2016 and is being fully funded by the Cigar Lake joint venture.


McClean Lake consists of nine known ore deposits, five of which have been mined out with some of the ore still stockpiled on the surface.

The first ore body, JEB, was mined from 1997 to 1999 and the ore was stockpiled. Mining of the Sue C ore body was completed in February 2002, and all of the ore was stockpiled on the surface. Mining was then suspended until the third quarter of 2005 when mining began on the Sue A, Sue E and Sue B deposits. Mining was completed at Sue A in the first quarter of 2006, at Sue E in the first quarter of 2008 and at Sue B at the end of 2008. Exploration activities for expansion of the known deposits and identification of new deposits are ongoing.

Low-grade special waste from the mining of the JEB, Sue C, Sue A, Sue E and Sue B deposits has been disposed of in the mined-out Sue C pit. There is also an agreement with the Cigar Lake joint venture to dispose of special waste from its mining operations in the Sue C pit. The costs of dewatering the Sue C pit at that time and the handling and disposing of the Cigar Lake wastes will be paid by the Cigar Lake joint venture.


During 2009 and the first six months of 2010, the mill processed stockpiled ore from the Sue E, Sue B, Sue A and McClean North deposits. The mill stopped processing new ore feed at the end of June of 2010 and the final circuit clean out was completed in October 2010. Approximately 94,800 tonnes of Sue B and SABRE (Surface Access Borehole Resource Extraction) ore at an average grade of 0.42% U3O8 remain on the stockpile.

The mill is anticipated to remain on care and maintenance to mid-2014. The first shipment of Cigar Lake ore arrived in March 2014. Subject to receipt of sufficient Cigar Lake Ore to start-up, the mill is projected to begin processing of ore in June 2014. Initially a blend of Sue B, SABRE and Cigar Lake ore will be processed, with the quantity of Sue B and SABRE ore declining through the year until only Cigar Lake ore will be processed. For the first six months when the mill is on care and maintenance, the Cigar Lake joint venture continues to pay for essentially all of the stand-by expenses according to the terms of the Cigar Lake joint venture toll milling agreement. Once operations begin McClean will pay a fixed cost for the processing of its ores and the Cigar Lake joint venture will pay the remaining operating costs.

In addition, a feasibility study evaluating the mining of the McClean North, Caribou and Sue D deposits via conventional underground methods was completed in 2012. A production decision has been deferred and will be reconsidered in 2014.

Tailings Disposal

The disposal of mill tailings in an environmentally acceptable manner has led to advances in the design and construction of new tailings management facilities. In the state-of-the-art TMF, tailings are deposited subaqueously in a paste form from a barge. This procedure minimizes tailings segregation, eliminates concerns of freezing and dust generation, and controls radiation and radon emissions from the pond. This facility has been designed to receive tailings from processing high-grade Midwest and Cigar Lake ores in addition to tailings from the McClean Lake deposits.

The first of two TMF projects has been completed. The first project maximized the capacity and the efficiency of the currently licensed tailings space through sloping the walls and the placement of a bentonite liner which will provide an additional two to three years of tailings capacity based on current projected throughputs. . The second project is a proposed expansion of the TMF, which would provide additional tailings capacity for the next 25 years.

Geological Setting

The McClean Lake uranium deposits lie near the eastern margin of the Athabasca Basin in the Churchill Structural Province of the Canadian Shield. The bedrock geology of the area consists of Precambrian gneisses unconformably overlain by flat lying, unmetamorphosed sandstones and conglomerates of the Athabasca Group. The Precambrian basement complex is composed of an overlying Aphebian aged supracrustal metasedimentary unit infolded into the older Archean gneisses. The younger Helikian aged, Athabasca sandstone was deposited onto this basement complex. The basement surface is marked by a paleoweathered zone with lateritic characteristics referred to as regolith.

The mineralized zones in the McClean trend occur as sausage–shaped pods straddling the unconformity between the Athabasca sandstones and the crystalline basement. The high grade part of the mineralized pods undulates from 13 metres above to 13 metres below the unconformity contact which is, on average, at a depth of 160 metres below the surface in this area. The host rocks for the mineralization are altered sandstones and Aphebian basement rocks usually altered to clay–rich rocks.

Generally, mineralization in the basement is at the eastern extremity of the combined zone. Uranium mineralization is hosted in hematitically altered clay–rich zones in which illite forms massive layers. Uranium occurs as fine–grained coffinite, as veinlets and nodules of pitchblende and as massive masses of pitchblende/uraninite. Highly variable but generally small amounts of nickel arsenides are associated with the uranium.


The McClean Lake Project includes the deposits of the Sue Trend, and the JEB, Caribou, and McClean Lake sandstone hosted deposits. The Sue Trend hosted five deposits, including Sue A, C, E and B that have all been mined. The collective deposits at the McClean project represented the 5th largest uranium resource/reserve in the Athabasca basin, and, in contrast to mature mining projects in other commodities and uranium in other jurisdictions, the exploration potential remains extremely high for the discovery of new economic mineralization.

There are a number of extremely high potential geologic targets at McClean that are either partially tested or not tested at all. One advantage of exploration at the McClean property is that the shallow depth to the unconformity, a maximum of about 170 metres, means cheaper open pit mining methods are possible, and a smaller target size is therefore economically possible to exploit.

Please see Annual Information Form and Quarterly Exploration and Development Updates and Financial Reports for further information.


McClean Lake


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