Both the Phoenix and Gryphon deposits are classified as Athabasca Basin unconformity-associated uranium deposits. Phoenix straddles the unconformity contact between the Athabasca Sandstone and underlying basement, while Gryphon is entirely hosted in the basement rocks.

Uranium mineralization at the Phoenix deposit occurs at the unconformity between Athabasca sandstones and basement rocks, with the most intense mineralization adjacent to the WS fault. A minor amount is basement fracture hosted mineralization extending below the north part of Zone A.

Mineralization and alteration have been traced over a strike length of approximately one kilometre. Since discovery hole WR-249 was drilled in 2008, 253 drill holes have reached the target depth, delineating two distinct zones (A and B) of high-grade uranium mineralization.

Mineralization is in the form of the oxide uraninite/pitchblende (UO2).

Average trace metal concentrations for Phoenix assay samples greater than 0.2% U3O8 are as follows: 576 ppm Ni, 194 ppm Co, 319 ppm As, 2,092 ppm Zn, 18 ppm Ag, 7,176 ppm Cu, and 9,143 ppm Pb. Average concentrations of Ni, Co and As are at the low end of the range found in other uranium deposits in the Athabasca basin.

Mineralization at Gryphon occurs 720 m below surface and is centred approximately 220 m below the sub-Athabasca unconformity. It is within 80 m of the unconformity at its highest point and 370 m below the unconformity a ........

Denison plans to mine the Phoenix deposit using the ISR extraction method with a low pH lixiviant. Uranium ISR uses the native groundwater in the orebody, which is fortified with a low pH solution and in most cases an oxidant. Pumping the solution through the ore zone and allowing the solution to contact the ore requires sufficient permeability of the ground.

Physically ISR mining is conducted through drill holes from surface to the orebody, known as wells. Wellfields are the groups of wells, installed and completed in the mineralized zones that are designed to effectively target delineated mineralization and reach the desired production goals. The mineralized zones are the geological sandstone units where the leaching solutions are injected and recovered via wells in an ISR wellfield. At present, the drilling of individual wells will be carried out utilizing either air rotary or mud rotary methods. The wellfield at Phoenix has been designed using a standard hexagonal pattern with 10m spacing between wells.

The uranium ISR process will involve the dissolution of the water-soluble uranium compound from the mineralized host sandstones at low pH ranges using acidic solutions. The acidic solution will dissolve and mobilize the uranium, allowing the dissolved uranium to be pumped to the surface within the mining solution.

Containment of the solution is a requirement in ISR operations to ensure recovery of the uranium and to minimize regional gro ........

The mill is currently configured to be fed from either the ore stockpile and grinding circuit or from the ore slurry receiving facility, which is currently used to receive high-grade material from Cigar Lake.

The grinding circuit, consisting of a SAG and ball mill, is currently not in service, and is available to the Gryphon feed.

Phoenix Deposit Processing at Wheeler River.
The uranium recovery or precipitation plant will house most of the process equipment in a 46,500 square foot pre-fabricated metal building. The plant will have four major circuits: impurities removal, yellowcake precipitation, dewatering/drying and packaging.

Uranium bearing solution containing dissolved uranium from the wellfields will be pumped to the precipitation plant for beneficiation as described below:
- pH adjustment – The pH of the incoming solution to the plant is constantly monitored and maintained at a specific value to ensure the uranium is fully dissolved through the addition
of acid.
- Impurities Removal – the uranium bearing solution is pumped to a series of agitated tanks where sodium hydroxide and barium chloride are progressively injected, along with a flocculant. The resulting increase in pH and the addition of barium chloride and flocculant promote the formation of metal hydroxides ........