The various underground workings of the Coalmont Colliery occur along the northeast bank of Blakeburn Creek, 1 to 3.5 kilometres northwest of Granite Creek, and 16.5 to 18.5 kilometres west-northwest of Princeton. The colliery is comprised of five mines, identified from southeast to northwest as the Nos. 1, 2, 3, 4 and 5 mines.
Coalmont Colliery is situated along the southwestern margin of the Tulameen Basin, a structural basin comprised of a northwest- striking syncline that preserves a sequence of sedimentary rocks, with lesser intercalated volcanics, of the Eocene Allenby Formation (Princeton Group), up to 840 metres thick. The sequence rests unconformably on a basement of Upper Triassic Nicola Group metamorphosed volcanics and sediments. The syncline doubly plunges towards the centre of the basin. In the northwest, the fold is open with both limbs dipping approximately 45 degrees. In the southeast, the fold is asymmetric with the dips being approximately 45 degrees and 20 degrees on the northeast and southwest limbs, respectively. The basin is bounded by high-angle faults and is dissected by additional high-angle northwest to northeast striking faults.
The mines are hosted in a coal-bearing shale member approximately 130 to 200 metres thick, underlain by up to 120 metres of sandstone, siltstone and andesitic volcanics, and overlain by 580 to 700 metres of sandstone and pebble conglomerate with interbeds of shale, ash and coal in the lower sections. The member consists of up to 30 metres of coal interbedded with shale, bentonite (ash) and sandstone. The coal occurs in the lower 80 metres of the member in a zone of mostly dirty coal and shale with lesser clean coal, averaging 21 metres thick, and ranging up to 37 metres in thickness. At least three major seams of cleaner coal are present in this coal zone. The aggregate coal thickness of the zone decreases to the north.
The underground workings at Coalmont Colliery are developed mostly in the Main seam, the uppermost seam in the coal zone. It strikes 146 degrees over most of its length and dips 18 to 30 degrees northeast, generally flattening with depth. To the southeast, in the Nos. 1, 2 and 3 mines the seam strikes approximately 168 degrees. It has been traced downdip in the No. 4 mine, the deepest of the five mines, for 970 metres. The five mines followed the seam over a total strike length of 2700 metres. Trenching and drilling northwest of the No. 5 mine indicates the enclosing coal zone continues for another 2300 metres, giving a total strike length of 5000 metres. The deposit is displaced vertically 150 metres along a northeast striking fault that separates the Nos. 1, 2 and 3 mines from the No. 4 mine. A dike is reported to follow this fault zone. A second fault, with a vertical displacement of 45 metres, separates the Nos. 4 and 5 mines.
The Main seam is 2.3 to 3.7 metres thick. In the Nos. 1, 2 and 3 mines, the seam is overlain by up to 0.3 metre of bentonite followed by 2.7 to 4.3 metres of dirty coal, and underlain by about 24 metres of interbedded dirty coal, clay and shale. To the northwest, in the No. 4 mine, it is overlain by up to 0.9 metre of bentonite.
A second seam of coal, separated from the overlying Main seam by 0.5 metre of intercalated sandstone and coal was mined in a limited way in the No. 4 mine. The seam is 2.1 metres thick, but the amount of mineable coal it contained was restricted to one or two small areas.
A third seam, 2.3 to 2.4 metres thick, lies 14.5 metres below the floor of the Main seam.
Northwest of the underground mines, the upper part of the coal zone contains a section 15 to 21 metres thick, comprised of beds up to 1 metre thick of clean to dirty coal and numerous thin rock partings. The section is in part equivalent to the cleaner coal mined in the underground workings. The rock partings consist of mudstone, coaly mudstone and bentonite. A seam of soft, light grey to cream-coloured bentonite up to 1 metre thick, occurs near the top of the coal interval, and is likely equivalent to the bentonite seam overlying the Main seam in the underground mines to the southeast. Dips over this portion of the coal zone range from 28 degrees in the south to 45 degrees to the north.
Open pit coal reserves (measured) are estimated at 7,418,280 tonnes, 9,240,230 tonnes and 11,232,000 tonnes, with strip ratios of 2.0:1, 2.5:1 and 3.0:1 respectively (Coal Assessment Report 200, page 22). This reserve estimate, totalling 27,890,510 tonnes, is for the 15 to 21-metre thick coal section lying northwest of the underground mines, over a strike length of 1500 metres and dip length of between 220 and 285 metres. A preliminary pit design suggests 10 million tonnes of raw coal can be extracted at an overall stripping ratio of 2.82 to 1 (Coal Assessment Report 200, page 23).
The coal is agglomerating but of generally poor coking quality and is high-volatile bituminous B and C in rank. Freshly exposed, the coal is black with a bright luster, and is commonly banded. The bright luster is attributed to its high vitrinite and low inertinite content. Nodules of bright clear amber (resinite) are widely scattered throughout the coal. Mineral matter consists primarily of quartz and kaolinite, with occasional siderite, orthoclase and sepiolite. Reflection measurements on the vitrinite (mean random reflection) in a 20 metre section exposed at the Blakeburn strip mine, ranged from 0.79 to 0.94 per cent, showing a general increase downward (Geological Survey of Canada Paper 72-39, pages 7 to 9). Five samples analyzed as follows (in per cent):
______________________________________________________________________ Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Moisture 7.9 6.00 5.30 5.7 3.9 Volatile matter - 26.60 30.10 31.3 31.7 Fixed carbon - 54.20 57.00 46.3 40.9 Ash 10.3 13.20 7.60 16.7 23.5 Sulphur - 0.40 0.30 0.4 0.5 Calorific value 11450 11470 11780 11030 10100 (B.T.U.'s per pound) Ash Fusion Temp. 1226 Celsius - - - - _____________________________________________________________________ |
Sample 1 is a bulk sample from either the No. 3 or No. 4 mines (Bulletin 14, page 20). Samples 2 and 3 are grab samples from the Nos. 3 and 4 mines, respectively (Bulletin 14, page 16). Sample 4 is a channel sample taken along the bottom 2.4 metres of the 24 metre thick coal zone exposed at the Blakeburn strip mine (Minister of Mines Annual Report 1954, page 235), and sample 5 is a chip sample taken across the same exposure over a stratigraphic thickness of 19.8 metres, (A.H. Lindley, 1962, pages 11, 12). Nine additional samples from the strip mine contained 2.41 to 5.09 per cent moisture, 21.38 to 34.42 per cent volatile matter, 39.98 to 63.11 per cent fixed carbon and 8.23 to 29.38 per cent ash (Geological Survey of Canada Paper 72-39, page 11). Samples from holes drilled northwest of the mines contained 36.54 to 41.17 per cent raw ash and 6640 to 7540 British Thermal Units per pound (air dry basis) (Coal Assessment Report 200, page 18, holes T-77-1 to T-77-5).
The deposit was initially explored by the B.C. Coal and Coke Company between 1908 and 1910. Columbia Coal and Coke Company (formerly B.C. Coal and Coke) continued development and eventually commenced production in 1912 with the opening of the No. 1 mine (nos. 2 and 4 tunnels). Coalmont Collieries Ltd. (formerly Columbia Coal and Coke) took over operations in 1914, opening up the No. 2 mine (nos. 2 and 6 tunnels) just west of the abandoned No. 1 mine in the same year. The No. 2 mine continued producing until 1923, and was replaced by the adjacent No. 3 mine to the west. This mine operated continuously between 1920 and 1935. Coalmont Collieries also operated the No. 4 mine (1924-1939) and the No. 5 mine (1936-1940), located successively farther northwest. Production from the deeper parts of the mines was limited by the squeezing of underground workings associated in part with the swelling action of bentonite seams. Total underground production amounted to 2,166,701 tonnes. Mullin's Strip Mine Ltd. produced an additional 148,268 tonnes at the Blakeburn strip mine between 1954 and 1957. This operation mined the 24-metre thick coal zone, situated between outcrop and the old workings of the No. 3 mine, in order to fuel Granby Consolidated Mining, Smelting and Power Company's steam-electric power station near Princeton. Total production between 1912 and 1957 is 2,314,970 tonnes.
Various operators explored the deposit for additional coal reserves between 1960 and 1982, including, Cyprus Anvil Mining Corporation between 1976 and 1982. The company conducted topographic, geological and geophysical surveys, trenching, bulk sampling and 1479 metres of diamond drilling in 12 holes. This work was focused on defining the northwestern extension of the mined coal measures.
A number of potentially economic bentonite seams up to 2 metres thick occur in the coal zone, which is correlated with the bentonite- bearing Vermillion Bluffs shale of the Princeton Basin (Open File 1987-19). Exchangeable cation analyses and cation exchange capacity (CEC) in milli-equivalents per 100 grams on two samples from a bentonite bed, 1 to 2 metres thick, in the upper part of the coal zone are as follows (Open File 1987-19):
________________________________________________________________ Sample Magnesium Calcium Potassium Sodium CEC T77-12 12.2 56.1 2.8 0.1 n.d. OP-79-1 21.2 32.6 2.0 0.0 n.d. ________________________________________________________________ |
Sample T77-12 is from a drill hole and sample OP-79-1 is from the Blakeburn strip mine. A sample from a bed of bentonite overlying the Main seam in the No. 1 mine analyzed as follows (in per cent) (Geological Survey of Canada Memoir 47, page 52):
__________________SiO2 56.33 Al2O3 28.36 Fe2O3 1.37 CaO 1.60 MgO 0.73 TiO2 0.40 Alkalies 2.00 H2O 9.56 Total 100.55 __________________ |
This bentonite is strongly coloured by organic matter, and is exceedingly plastic, but has high air shrinkage at 11.8 per cent. Firing characteristics are as follows (Geological Survey of Canada Memoir 47, page 52):
______________________________________Cone Fire shrinkage Absorption (per cent) (per cent) 010 <1 2.5 05 nil 0.0 1 nil 0.0 ______________________________________ |
The clay cracks and warps during burning, but burns to a hard, cream- coloured body at cone 010. It is vitrified but not viscous at cone 20. A second sample of calcareous clay (bentonite?) from the No. 1 mine had average air shrinkage of 8.3 per cent and an average tensile strength of 150 pounds per square inch (Geological Survey of Canada Memoir 47, page 51).
Pacific West Coal Limited drilled, prepared a site for a 10,000 tonne bulk sample and conducted an environmental study in 1997 and 1998. They propose to mine 100,000 tonnes per year of high-volatite C to B bituminus coal.
Compliance Energy Corp. made a production decision based on a feasibility study completed in 2002 (Press Release, September 17, 2002). The project is a joint venture between Compliance Coal Corp. and Nissho Iwai Coal Development (Canada) Ltd.. Plans include trucking selectively mined coal to a wash plant at the Similco mine site (MINFILE 092HSE001).
In 2002, partners Compliance Energy Corp. (65 per cent) and Nissho Iwai Canada Ltd. (35 per cent) mined about 10,000 tonnes of thermal coal at the Basin Coal project. The project was formerly known as the Tulameen project. The project, with measured and indicated resources of 19 million tonnes, has a permit for up to 250,000 tonnes of annual coal production.
In 2003, at the Basin coal deposit, a joint venture of Compliance Energy Corp. (65 per cent) and Nissho Iwai Coal Development (Canada) Ltd. (35 per cent) extracted 20,000 tonnes of clean thermal coal.
In 2004, at the Basin coal mine, production of clean thermal coal more than doubled to about 40,000 tonnes. The operation was reported to be a joint venture of Compliance Energy Corp (65 per cent) and Sojitz Coal Development Ltd (35 per cent).
In 2005, the small Basin thermal coal mine expanded production to about 75,000 tonnes. The high volatile, bituminous B and C rank coal is sold mainly to cement plants and small greenhouse growers in southern BC. Compliance Energy Corp consolidated ownership of the property and improved the efficiency of the operation by moving the wash plant to the mine site. It was formerly at the Similco mine site, which will continue to serve as a load-out for highway trucks.
During 2006 the Basin mine produced 42,000 tonnes (Exploration and Mining in BC 2006 pg. 78). It ceased production and went on care and maintenance in September 2006. In 2008 minor amounts of stockpile were sold.
In a 2009 technical report completed for Compliance Energy Corporation reported combined measured and indicated resources as 87.015 million tonnes and inferred resources as 36.685 million tonnes (Technical Report for Compliance Energy Corporation, September 4, 2009, www.sedar.com)
In 2011 Coalmont Energy Corporation, a wholly-owned subsidiary of Arthon Industries Limited, acquired the Basin Mine from Compliance Energy. The company upgraded a logging road connecting the mine with the Coquihalla Highway, and built a new wash plant. The mine resumed production from June to October 2013, producing 100,000 tonnes of thermal coal that year (Information Circular 2014-5).
