Details


SMDI #
1130
Current Showing Name
Key Lake Uranium Mine [Gaertner Orebody, Cobble Orebody]
Historical Showing Names
Key Lake Uranium Mine [Gaertner Orebody, Cobble Orebody], Key Lake Uranium Mine: Gaertner Orebody, Cobble Orebody
Company Name
Cameco Corporation, Orano Canada Inc.
Project Name
Key Lake
UTM Easting (NAD83 Z13)
459754.5000
UTM Northing (NAD83 Z13)
6339970.0600
NTS Sheet
074H04
TRM (Township-Range-Meridian)
94-23-2
Primary Commodities
Uranium
Associated Commodities
Arsenic, Copper, Lead, Nickel, Zinc
Discovery Type
Status
Deposit: Post-Production
Geological Details
The Gaertner Orebody, one of the Key Lake Deposits, consists of a narrow, elongate fairly shallow body extending from Seahorse Lake to the northeast end of Karl Ernst Lake. The Archean basement consists mainly of granite gneiss and granulite, and is unconformably overlain by a heterogeneous pelitic to semipelitic basal unit and a younger meta-arkose sequence of Aphebian age. The sequence was deformed into regional northeast-trending folds and metamorphosed to upper amphibolite facies during the Hudsonian orogeny. Regional weathering caused formation of the regolith. Overlying the entire sequence is the Helikian-aged Athabasca Formation, composed of sandstones and quartz conglomerates up to 100 m (328.1 ft) thick, overlain in turn by Pleistocene glacial deposits 20 to 100 m (6.1 to 30.5 m) thick. No outcrops have been found in the vicinity of the orebody. The structure of the orebody is controlled by the intersection of two main structural features, the unconformity at the base of the Athabasca Formation and an east-northeast-trending fault zone that crosses the unconformity and dips 40° to 60° to the north. The Gaertner orebody is located in the hanging wall of this fault. Uranium mineralization is located in three rock units. The upper section of the ore body is contained in horizontal beds of sandstone and conglomerate; the central portion occurs in kaolinitized residual rock (regolith) and the lower section occurs in a sequence of biotite gneiss, graphitic gneiss and subordinate pegmatoid bodies. All three units are cut by a subvertical shear zone. The orebody shows a vertical zoning of uranium with the maximum concentration in a narrow central zone. The mineralization intensity diminishes upwards and downwards.The oreodies were once covered with 20 to 100 m (6.1 to 30.5 m) of sediment, but some of the ore was removed by glaciation and has accumulated as ore-bearing cobbles above the ore body. The internal structure of the orebody is very complex but relatively consistent internal structures have been noted. Ore shoots start in the lower basement as vein-like features conformable with the foliation and within shear zones parallel to the foliation. Their thickness increases upwards, and finally they develop into more irregular bodies. Within the Athabasca sandstone the orebodies are mainly confined to shear zones and to complimentary joint systems. One of the characteristics of the Key Lake deposits is the close association of uranium and nickel. The ore grades are extremely variable and range up to 35% U3O8 and 20% Ni over 2 m (6.6 ft) vertical. High concentrations of uranium and nickel mineralization generally coincide, but the nickel tends to be concentrated at levels slightly below the uranium. Uranium minerals include euhedral and radially textured pitchblende, sooty pitchblende and coffininte. The main ore minerals are gersdorffite, millerite, niccolite and bravoite. Pyrite, galena, safflorite, sphalerite, chalcopyrite, hematite and magnetite were observed in lesser amounts. Diamond drilling has delineated the Gaertner orebody to extend over a 1400 m (4593.2 ft) length, with the richest part having a length of 800 m (2624.7 ft), average width of 10 to to 50 m [32.8 to 164.0 ft] and average thickness of 60 m (196.9 ft). A lower grade zone, containing some richer pockets, extends over a length of 600 m (1968.5 ft) with an average width of 10 m (32.8 ft) and thickness of 3 m (9.8 ft). At the Gaertner Deposit, mineralization occurs as veins, massive nodules, and disseminations within down-faulted Athabasca Group sandstones.The sandstone host is extensively fractured, quartz corroded, and clay altered. Some mineralization extends to a depth of 30 m (98.4 ft) into the underlying altered, folded,and mylonitized Early Proterozoic graphitic basement biotite gneisses. The Cobble orebody consists of a zone of mineralized overburden (glacial deposits) which has a sufficent concentration of uranium mineralized boulders that it forms ore.
Geological Domain
Wollaston
Host Rocks
Host Minerals
Arsenopyrite
Indicators
Exploration History
12/1/2023 The remaining production of uranium for 2022 came from the recently restarted McArthur River–Key Lake (Cameco) operation, which yielded a total of 1.1M lb (498.9 t) U3O8 (100 per cent basis) in the fourth quarter of 2022. Cameco has predicted a total production of 14.0M lb (6350.3 t) U3O8 in 2023 from this operation. Production forecasts for 2023 have been adjusted from 15.0M lb (6803.9 t) U3O8 due to equipment reliability issues coming out of care and maintenance, availability of skilled and experienced personnel, supply chain challenges on the availability of materials and reagents, and operational changes that were implemented while restarting the McArthur River–Key Lake operation. (Saskatchewan Exploration and Development Highlights 2023, p.7) (See also Production and Reserves/Resources, from Saskatchewan Exploration and Development Highlights 2023, Table 1, p.7) 6/14/1989 The Key Lake area of Northern Saskatchewan was first explored in 1971. Exploration had begun to be focussed in this part of Saskatchewan as a part of the discovery of the Rabbit Lake deposit in 1968. Anomalous radon concentrations which warranted further exploration work were noted in the Zimmer Lake area (located on-strike of the Key Lake deposits and to the southwest) in 1971. The search for the cause of the anomalies led to the discovery of two massive uranium-nickel mineralized boulders, located aproximately 5 km southwest of the Key Lake Deposits. Over the next two years, radioactive swamps and boulder fields north of Zimmer Lake were examined in hope of locating their source (AF 74H04-0009). A diamond drill program (12 holes) was completed, as well as EM and seismic surveys (AF 74H04-0005), but no ore-grade material was intersected. Airborne radiometric surveys, geological mapping, geochemical sampling and photogeological surveys were completed as well (AF 74H04-0008;-0009;-0010). During the summer of 1974 a radon survey was completed in the area of geophysical anomalies (AF 74H04-0013). A low order anomaly was noted (and later realized to be 50 m northwest of the Deilmann orebody) but not felt to be interesting or important. Ten BQ drill holes were completed on the showing (AF 74H04-0013) but no apparent mineralization was intersected. The first drill hole intersected a graphitic horizon at the intersection of a very low EM conductor and IP anomaly. It was felt that this graphitic horizon was the cause of the anomalies in the area. It was not until a year later when it was realized that this drill hole had intersected the root of the Deilmann orebody. A grid mag, EM and IP surveys were completed on the area at the same time (AF 74H04-0016). Linecutting, ground EM and mag surveys were completed over the area in 1975 (AF 74H04-0021). Drill hole 25 discovered the Gaertner mineralization. Drilling continued in 1975 along a conductor at the northeast end of Karl Ernst Lake (74H04-0017). Drill hole no. 15 intersected a 15 m interval of radioactivity but no drill core was returned. Two drill holes were completed between the Gaertner and Deilmann deposits and each intersected only minor radioactive zones. These were, at first, believed to be caused by the presence of uraniferous boulders in the vicinity of the drill holes. A combination vertical and horizontal loop EM survey was completed to outline promising drill targets (AF 74H04-0017). An extensive, closely-spaced diamond drill program was planned on the land bridge between Seahorse and Karl Ernst Lakes (AF 74H04-0021). 166 drill holes were completed. Drill hole no. 25, completed 29 July 1975, was the first drill hole to intersect high grade uranium mineralization of the Gaertner Deposit. Development drilling followed and the orebody discussed above was outlined. A final determination of the Gaertner deposit was planned for 1977. The Deilmann deposit was intersected in June of 1976 (see SMDI 1131). Diamond drilling continued and by 1979, 2427 drill holes totalling 266,000 m had been completed (AF 74H04-0024). By 1977 an environmental baseline study was begun and a formal exploration permit was obtained from the Atomic Energy Control Board in April of 1977, which gave approval for diamond drilling, test-pitting, and assay and bulk sampling. Lake de-watering was also approved. An underground exploration permit was granted 14 December 1977. Key Lake Mining Corporation was officially formed on 1 March 1979 to bring the area into production. In 1981, Uranerz completed VLEM, shallow refraction seismic and soil and soil hydrocarbon test surveys over the deposit area (AF 74H04-0072,0073 and 0081). In 1982, Uranerz completed fixed wing gradiometer and magnetic surveys and ground HLEM, VLF-EM, resistivity and magnetic and gradiometer surveys (AF 74H04-0074,0075 and 0082). In 1983, Uranerz completed core magnetic susceptibility studies, ground magnetic susceptibility and resistivity surveys (AF 74H04-0076, 0077, 0083). Extensive preparation was completed before mine start-up was achieved on 3 October 1983 (the date of the first ore feed). The first yellowcake was produced on 21 October 1983. The mine was slated to have a yearly capacity of 10 to 12 million lbs (5.4 million kg) U3O8 or a daily capacity of 780 tons. Between 1979 and 1983, Uranerz completed a series of hydrogeological, dewatering, geological and project engineering studies on the orebody (AF 74H04-0068). During the same period of time, further prospecting was completed on the lease (AF 74G-0013 and -0014). In 1984, Uranerz completed one drill hole (no. GP-1) in the Gaertner open pit (AF 74H04-0091;-0084). In 1985, Uranerz completed a DEEPEM survey over Key Lake Island grid and completed drill holes KLI-8, P-10 and P-11 in the Key Island-Boundary Creek area (AF 74H04-0093;-0085). No significant mineralization was intersected. Uranerz also lithologically mapped the tills in the west zimmer trenches (AF 74H04-0094). This work led to the conclusion that the West Zimmer radioactive boulder train/ dispersion fan source was the Key Lake orebodies. At the same time, the deposit area was detail mapped by Ramaekers. There was no production from the Key Lake Mine after July of 1999 as the mill was being reworked to process McArthur River ore. In 2000, the mill processed ore from the low grade stockpile (mixed McArthur River ore and Key Lake waste grading 3.4% U).
Production History
Production Period: 2022-10-01 to 2022-12-31 Cameco Corporation: Summary: - Uranium Production Period: 2002-01-01 to 2002-12-31 (open pit) 19,000.00 tonnes The Key Lake Mine was initiated to exploit the Gaertner, Deilmann and Cobble orebodies. Open pit mining commenced on the Gaertner deposit in 1981 and mine construction was completed September 1983. First ore received secondary crushing on 3 October 1983 and the first yellowcake was shipped 21 October 1983. The Gaertner pit was mined from 1983 to 1986. At the end of 1986, the Gaertner pit was closed and decommissioned. The Deilmann open pit commenced operation in 1989 and was mined out in May of 1997. The last ore was milled in 1999. At this time, the Deilmann open pit was converted into a tailings facility to hold McArthur River Mine tailings. KEY LAKE MINE ANNUAL PRODUCTION FIGURES _______________________________________ YEAR TONNES PRODUCTION RECOVERY MILLHEAD YEAR END MILLED (LBS. U3O8) RATE GRADE RESERVES _______________________________________________________________ 1983 24,877 1,123,476 93.90% 2.41 pre-production 1984 163,988 10,407,474 96.90% 2.95 185,000,000 1985 195,157 11,101,776 95.30% 2.72 174,000,000 1986 248,415 12,586,107 97.90% 2.31 161,000,000 1987 282,698 13,516,676 97.80% 2.21 147,100,000 1988 241,929 12,033,339 98.40% 2.29 135,000,000 1989 242,890 12,719,522 98.50% 2.40 123,000,000 1990 263,769 12,935,282 98.70% 2.25 110,000,000 1991 262,491 14,094,298 98.80% 2.44 95,700,000 1992 263,417 14,174,158 98.70% 2.45 81,300,000 1993 288,251 13,817,503 98.00% 2.22 77,500,000 1994 262,881 13,189,962 96.95% 2.32 69,900,000 1995 299,569 14,203,729 97.40% 2.20 51,800,000 1996 321,083 14,113,866 97.90% 2.03 36,001,487 1997 315,282 14,126,539 97.00% 2.09 ---------- 1998 323,382 14,000,000 97.40% 2.01 12,400,000 1999 215,703 9,700,000 96.50% 2.07 2,200,000 2000 90,000 1,044,000 94.75% 0.53 1,195,000 2001 83,000 778,000 98.40% 0.43 938,000 2002 19,000 228,000 98.93% 0.56 708,000 2003 0 0 ------ ---- 708,000 2004 0 0 ------ ---- 708,000 2005 0 0 ------ ---- 708,000 2006 0 0 ------ ---- 708,000 _______________________________________________________________ Summary: - Uranium: 228,000.00 lb @ 0.56 % Production Period: 2001-01-01 to 2001-12-31 (open pit) 83,000.00 tonnes Summary: - Uranium: 778,000.00 lb @ 0.43 % Production Period: 2000-01-01 to 2000-12-31 (open pit) 90,000.00 tonnes Summary: - Uranium: 1,044,000.00 lb @ 0.53 % Production Period: 1999-01-01 to 1999-12-31 (open pit) 215,703.00 tonnes Summary: - Uranium: 9,700,000.00 lb @ 2.07 % Production Period: 1998-01-01 to 1998-12-31 (open pit) 323,382.00 tonnes Summary: - Uranium: 14,000,000.00 lb @ 2.01 % Production Period: 1997-01-01 to 1997-12-31 (open pit) 315,282.00 tonnes Summary: - Uranium: 14,126,539.00 lb @ 2.09 % Production Period: 1996-01-01 to 1996-12-31 (open pit) 321,083.00 tonnes Summary: - Uranium: 14,113,866.00 lb @ 2.03 % Production Period: 1995-01-01 to 1995-12-31 (open pit) 299,569.00 tonnes Summary: - Uranium: 14,203,729.00 lb @ 2.20 % Production Period: 1994-01-01 to 1994-12-31 (open pit) 262,881.00 tonnes Summary: - Uranium: 13,189,962.00 lb @ 2.32 % Production Period: 1993-01-01 to 1993-12-31 (open pit) 288,251.00 tonnes Summary: - Uranium: 13,817,503.00 lb @ 2.22 % Production Period: 1992-01-01 to 1992-12-31 (open pit) 263,417.00 tonnes Summary: - Uranium: 14,174,158.00 lb @ 2.45 % Production Period: 1991-01-01 to 1991-12-31 (open pit) 262,491.00 tonnes Summary: - Uranium: 14,094,298.00 lb @ 2.44 % Production Period: 1990-01-01 to 1990-12-31 (open pit) 263,769.00 tonnes Summary: - Uranium: 12,935,282.00 lb @ 2.25 % Production Period: 1989-01-01 to 1989-12-31 (open pit) 242,890.00 tonnes Summary: - Uranium: 12,719,522.00 lb @ 2.40 % Production Period: 1988-01-01 to 1988-12-31 (open pit) 241,929.00 tonnes Summary: - Uranium: 12,033,339.00 lb @ 2.29 % Production Period: 1987-01-01 to 1987-12-31 (open pit) 282,698.00 tonnes Summary: - Uranium: 13,516,676.00 lb @ 2.21 % Production Period: 1986-01-01 to 1986-12-31 (open pit) 248,415.00 tonnes Summary: - Uranium: 12,586,107.00 lb @ 2.31 % Production Period: 1985-01-01 to 1985-12-31 (open pit) 195,157.00 tonnes Summary: - Uranium: 11,101,776.00 lb @ 2.72 % Production Period: 1984-01-01 to 1984-12-31 (open pit) 163,988.00 tonnes Summary: - Uranium: 10,407,474.00 lb @ 2.95 % Production Period: 1983-01-01 to 1983-12-31 (open pit) 24,877.00 tonnes Summary: - Uranium: 1,123,476.00 lb @ 2.41 %
Reserves and/or Resources
2023-12-01 Summary: Key Lake: Proven and Probable Mineral Reserve of 700,000.00 lb - Uranium @ 0.52 % 2021-12-31 Summary: Key Lake: Proven Mineral Reserve of 61,100.00 tonne - Uranium: 700,000.00 lb @ 0.52 % 2002-01-01 Reserves of 272 t U grading 0.44% U. Summary: Historic reserve (unspecified) - Uranium: 272.00 ton @ 0.44 % 1995-02-24 Key Lake deposit mineable reserves: 1,554,000 tonnes ore grading 1.58% U3O8 (81,300,000 lbs U3O8). Summary: Key Lake: Historic reserve (unspecified) of 1,554,000.00 tonne - Uranium: 81,300,000.00 lb @ 1.58 % 1983-01-01 Proven reserves given at time of mine opening: 182.4 million pounds uranium oxide with an average grade of 2.5% U3O8 per ton. Summary: Historic proven reserve - Uranium: 182,400,000.00 lb @ 2.5 %
Go back