Berlin wrote:looks like some good stuff. Eastern coals like those in parts of Maryland typically have a high ash fusion temp and won't clinker easily. The problem with most eastern coals - especially low/mid volitile eastern coals is that they tend to have a high coke button and a high propensity toward agglomerating. This is when the coal melts together during burning and creates a mat of coke that is difficult to break up- coals that do this are no good for hand-firing, they'll make the occasional soot problem seem like a dream.
This Big Vein coal definitely swells more than the stuff I got up at Valier's, but not as bad as the stuff I got from Country Coal at Somerset. I threw 2 big chunks of the stuff from country coal in the stove, they expanded so much that I had coal falling out of the loading door when I opened the stove. The stuff from country coal put out good heat but it was very crumbly, and their ROM looked to have lots of fines in it.
It seemed that both of these coals broke apart fairly easy though after a 12 hour burn. I was somewhat concerned about how much the coal swells, in regards to how much force that puts against the inside of the stove, and if it could damage anything. I had seen this on Norfolk Southern's website when searching for "Coke Button"
Norfolk Southern Website wrote:
Coke button (See FSI) — A button-shaped piece of coke resulting from a standard laboratory test that indicates the coking or free-swelling characteristics of coal. A coke button is usually expressed in numbers from one to nine. This represents the size of the coke as compared to a standard. The more a coal swells and cokes, the higher the number assigned to it.
Expansion/contraction — As coal is coked, it contracts and expands to a certain degree. The pressure exerted on oven walls due to expansion may be great enough to cause damage to the walls. The expansion/contraction properties can be determined in laboratory tests.
Free swelling index (FSI) — A measure of the tendency of a coal to swell when heated under controlled conditions. It is used as an indication of the caking characteristics of coal when burned as a fuel. It is not recommended for determining the expansion properties of coals in a coke oven.