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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 JEB pit was then converted in 1999 into the JEB Tailings Management Facility ("TMF"). 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. The mill operated until the end of June 2010 producing approximately 49.9 million pounds U3O8 when it was placed on stand-by due to a lack of ore.

In 2014 the McClean Lake mill re-commenced operations with the delivery of ore shipments from the Cigar Lake Mine, owned by the CLJV and operated by Cameco Corporation ("Cameco").

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 is specially designed and constructed to process high grade uranium ores in a safe and environmentally responsible manner. The 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, an electricity transmission line tied into the provincial power grid, a 14 megawatt back-up diesel power plant, warehouses, shops, offices and living accommodations for site personnel

In 2014 the McClean Lake mill re-commenced operations and processed over 456,800 pounds of U3O8 with a 97.5% recovery rate. Re-start of the mill proceeded smoothly with no significant production problems. Mill feed consisted of a blend of Cigar Lake ores and stockpiled Sue B and McClean Lake North ores (mined via SABRE). In 2015, production ramped up and the mill produced approximately 11.3 million pounds of U3O8 with a 98.9% recovery including several months with production over 1.5 million pounds. Mill feed was primarily CLJV ore. Overall mill performance was acceptable with no major upsets in the areas of safety, the environment or production. Mill personnel continue to refine operational practices and procedures to further improve performance.

In the second quarter of 2016 the Canadian Nuclear Safety Commission ("CNSC") authorized an increase to the annual rate of production at the McClean Lake mill, from 13 million pounds U3O8 to up to 24 million pounds U3O8 per year. The regulatory approval supports a progressive ramp-up of the mill in line with the Cigar Lake mine's expected annual production of up to 18 million pounds U3O8 per year starting 2017.


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 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. The mill was put on care and maintenance through the remainder of 2010 and remained on care and maintenance until resumption of operations in September 2014. The mill began processing a blend of Sue B and ore from the SABRE program and then began to blend in Cigar Lake ores. The mill shut down in late December for a maintenance shutdown over the Christmas period.

Approximately 90,700 tonnes of Sue B and SABRE ore at an average grade of 0.38% U3O8 remain on the stockpile.

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.

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.

In 2013, the TMF Optimization project was completed, which provides additional tailings capacity by increasing the efficiency of the currently licensed tailings space. This project entailed sloping of the TMF walls and placement of a bentonite liner and provides several years of tailings capacity based on current projected throughputs. A second project called the TMF Expansion is currently underway and when completed will provide an additional 25 years of tailings capacity. This project entails expanding the TMF above the currently licensed elevation and will require the submittal of an amendment to the operating licence. The environmental, engineering and licensing work are underway and a formal submission to the applicable regulatory agencies is expected in 2016. Construction of the TMF Expansion will commence after receipt of regulatory approvals and as required by the progress of mining and milling operations.

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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