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Copyright, Don Sinclaire, 2011
The graph below shows the percentages of the main components of coal. Coal ranges from anthracite on the left to sub-bituminous and lignite on the right. I created the graph based on samples described in Alberta Research Council reports.
The main components are:
1) Sulphur - 0.2-0.8%, contributes to the smell of the coal fire, too small to show on graph.
2) Ash - Typically 4 to 10%, forms the clinker in the bottom of the fire pot. Severity of clinker formation depends not only on the percentage of ash but also on the amount of coal fed into the fire in order to get the necessary heat.
3) Moisture - This is the natural water that is in the coal as it is found in the seam, not the moisture added or removed later. The moisture content is not a big issue for smithing purposes, since we water the coal down anyway, but it can be an indirect indicator of volitiles in the coal and the grade of coal. High moisture content results in a "poor storage" rating of the coal since the lumps start to fall apart as the coal dries out- also not an issue for us. The only down side of moisture in coal is that you are paying for it--- a 400 pound barrel of domestic coal will have 100 pounds of water in it.
The remaining items are the ones that contribute to the heat output of the coal:
4) Fixed Carbon - Pure carbon that we burn as coke in the firepot. This is our main source of heat.
5) Volatiles - Gasses, oils and tar in the coal. These ignite at a lower temperature, and help keep the fire burning (Anthracite for example has very little volatile material and will go out as soon as you stop the blower). In a power plant, the volatiles contribute to the total heat output of the coal, but for smithing purposes, we burn off the volatiles in the coking process, and that heat goes up the chimney. Most of the heat we actually use comes from the fixed carbon.
For smithing purposes, we want low to medium volatile bituminous coal---enough volatile material to keep the fire burning, make the coal "sticky" to form lumps of coke and to make the coke porous. High volatile bituminous coal will not coke, and even thought it may have high BTU/pound output, a significant amount of that heat is lost up the chimney.
In Alberta, Antracite is found in the Cascade region near Banff. Low to medium volatile bituminous coal is found in the Grande Cache and Cadomin (Luscar mine) and in the Crowsnet Pass area. These areas produce "Metalurgical Coal" which is what we want. Unfortunately all of it is shipped out in unit trains and they won't sell us any in small (truck load) quantities.
Even at Robb, which is relatively close to Cadomin, the coal is high volatile bituminous and sub-bituminous and suitable only for heating. The Alberta Research Council maps show that as you go east of the Rockies, the moisture content (and volatiles) goes up rapidly and the BTU/pound drops. There were no reports of any "metalurical" or "smithy" coal anywhere on the Prairies.
Analysis of Alberta Coal, Report #14, Scientific and Industrial Research Coucil of Alberta, 1925.
Coals of Alberta - Their Occurrence, Analysis and Utilization, Edgar Stansfield and W. Albert Lang,
Research Council of Alberta Report No. 35, 1944
Catalogue of Coal Mines of the Alberta Plains, Research Council of Alberta, 1964.
Coal Quality Variation in Alberta Tertiary Coals, D. Nikols and S. Treasure, 1990.
2010 NI 43-101 Technical Report, Grande Cache Coal Corporation, 2010
From: Scientific and Industrial Research Coucil of Alberta, 1925. The maps above are a bit difficult to read, but are included to show how the coal grades fall off as you go east of the Rockies.
Research Council of Alberta, 1944