So for all the veins of interesting and deep analysis it sounds like musician’s poetic-choice. Given a former version mentions number foar coal. Like the Beetles: “Number nine, number nine, number nine …”
One of the most interesting things about the Dope is how often things I was taught in my youth are wrong. I was told - by a science teacher - that it referred to the hardness of the coal. Since I was a kid and teachers were never wrong, this is what I’ve believed all my life. This is what makes coming here so much fun.
Nope - while coal in a particular seam in a particular region of a particular basin could be especially hard, there is no direct link. Coal hardness is also something which is difficult to measure.
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There is a “hardness” in terms of a Mohs hardness, which is very rarely used and of little practical value (with US anthracite generally being harder than bituminous which is harder than sub-bituminous which is harder than lignite…note this may not hold true in other parts of the world, for reasons which I won’t go into).
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There is also the practical hardness or “grindability” of the coal, which is usually measured by a lab test involving a small grinder and which generates a number called the Hardgrove Grindability Index. This is a dimensionless number which tends to range from 35-60 for US coals, with really difficult to grind coals being 35 or less, and really easy to grind coals being 55 or higher.
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Finally, there is also a pseudo “hardness” which is determined by the abrasiveness of the coal, which is actually a function of the inherent and external minerals which are supplied with the coal - typically (in the US - other countries use a variety of methods) this is estimated by an index like the so-called “quartz index”, which is silica content - 1.5*alumina content (on a dry, ash-only basis). However, there are numerous variations on that index even within the US, and completely different ones as well.
But no, the seam number does not have any direct correlation with the hardness.
Oh I wasn’t doubting you at all - I know you know your stuff. I was just relating why I still enjoy coming here after nearly 10 years.
I wonder how many other things my teachers made up?
There was in years gone by a set of descriptors on a coarseness/fineness consistency basis used for the degree to which coal was pulverized for varying uses. Terms such as “stove coal” or “pea coal” referred not to the grade of coal but to its consistency on a cobble/pebble/sand-grain sort of scale. I found this near-defunct terminology online here.
Una -
any idea if Number 9 is met coal or steam coal?
In the electirc business, we usually just break out East App, West App, Powder River, and Illinois Basin. We mostly care about SO2 (high for the scrubbed plants, low for unscrubbed); heat content (obviously) and price. MTR or not matters - mostly as it applies to ash content and politics.
I’m guessing the met guys are looking at some different things.
Question, when coal is burned in a power plant what form is it in? Crushed to powder, large chunks, small pieces like Kingsford charcoal?
Most of the modern plants crush them into a powder, some units use ‘cyclone’ furnaces that burn 2 inch or so sized chunks. And some newer units are being built for gassification of the coal that will actually make the plant more like a Combined Cycle gas plant than a coal plant, with the potential for better emissions removals technology.
East and west App? Don’t you mean North and Central? While there is a “West” region to the Appalachian production region (which is typically high-sulfur, high-iron bituminous coal) and I guess the North, Central, and South could be lumped together as “East”, in my nearly 2 decades of work it’s very rare that I hear the terms west and east.
While you can coke a lot of coals, generally speaking #9 is not metallurgical coal.
Pulverized coal plants in the United States, which make up most of the large utility coal plants, tend to crush coal to a consistency of 60-80% passing through a 200 mesh screen, which means about a 74-micron hole. In other words, very fine - it feels like rough talcum powder when I grab it. Stoker furnaces, which probably outnumber pulverized coal units and which are typically used for small applications, can burn coal sized as large as 2 inches (or even 3 or more inches in rare cases). Cyclone combustors tend to burn coal sized from 0.5-inch to 1.5-inch, although some work with larger pieces. Which size of coal is ideal for a cyclone combustor is a bit of a balancing act, as you do not want combustion to happen too soon (and overheat the cyclone barrel) or too late (and get huge amounts of unburned coal blown into the slag or in the fly ash). Fluidized bed boilers work with a range of sizes which are often 1 to 2-inch - this also depends upon the type of bed material which is used. It’s sort of an involved question.
Yes - bit of brain hiccup there… [ETA: although, honestly, our usual term terms in my group are high sulfur NS, lower sulfur NS, high sulfur CSX, and low sulfur CSX - just because that’s how we usual view pricing (and we look at everything in $/mmbtu, so heat content doesn’t really matter)]
I was just looking through my old NS Horsepower guide and I see Mine Number 1131 as having the name:
US #9
It’s is Gary, WV, in the Pocahantas District - owned by Raw Coal Mining Co.
Think there’s any chance the songs are referring to this mine?
Merle Travis was from Muhlenberg County, Kentucky, about 200 miles from the start of the larger and better-known coal field in the Kentucky Appalachians and about 400 miles from Gary, W.V. Muhlenberg County is in the heart of the Western Coal Field and is perhaps best-known outside Kentucky for the reference in Paradise, which begins, “Daddy, won’t you take me back to Muhlenberg County.”
“If you’d like to have a logical explanation
How I happened on this elegant syncopation,
I will say without a moment of hesitation
There is just one hole
Fit for number nine coal
Gary, West Virginia,
Gary West Virginia,
Not Louisiana, Paris, France, New York, or Rome, but–
Gary, West Virginia,
Gary, West Virginia,
Gary West Virginia,
My home sweet home.”
Awesome, US #9 it is then, I’d say - I knew that book would come in handy one of these days.
My roomie the blacksmith says that specific coals are looked for because of their levels of impurities, and how they can positively or negatively affect whatever project they are working upon.
Yeah, that’s pretty much the way it is in the coal, power, and metallurgical industry world-wide, and what I’ve studied for nearly 20 years now.
And yet, here we are five years later… 
If you mix #9 coal into some sort of dilute paste, could you use it as an aphrodisiac?