"Big Vein" coal from Georges Creek Field - MD

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.

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.