Anthracite Quality Vs. Density (Weight Per Unit Volume)?

To my knowledge, anthracite coal is separated from rocks and debris by floating it (whereby the undesirables sink). This would indicate that carbon is lighter than rocks and presumably some other coal contaminants that lead mainly to ash in the end.

By inference, and therein extending the above logic one step further, while at the same time assuming that all other factors remain equal (such as size uniformity, degree of fines, volatiles, etc...) to as high a degree as is possible, the more carbon content, the less dense should be the coal. If this is sound logic, then the coal that weighs the least in a full pail (or by any other volume unit of measure one may choose) should potentially have the highest carbon content. And since in the end carbon content is what is ultimately desired in high quality anthracite, higher carbon content should mean more potential BTU's. And lighter anthracite should have higher carbon content.

Short version: If you have some really light weighing yet full anthracite coal pails, all else being equal, you just might have some great anthracite there!!!

Does this sound right?

Not necessarily. I used Harmony which was a great coal. It weighed 32-35 pounds per bucket on average. The Lehigh is much heavier. It goes 38-39 pounds per bucket. It all comes down to how much heavier low grade coal is mixed in with it to get it to burn properly. Coal has to have a certain percentage of ash to keep from clinkering. The more dense(heavier) the coal is, the less ash it will generate. You have to mix more bone in it to get it to burn right. Harmony was a great coal because it burned great with low ash. It was the perfect density that it didn't need fillers. The "fillers" are what effect the weight in the end.

Scottscoaled wrote: The "fillers" are what effect the weight in the end.

Do more fillers mean less BTU's?

UAE Harmony pea weighted noticeably less in my pails than any other coal I've used to date, and was probably the best coal I've burned to date.

Actually,not exactly, but this is getting at the difference between met coal( metallurgical)and steam coal(coal to make heat).Met coal is higher in carbon,more desirable for that purpose,and steam coal is higher in volatiles,more desirable for heat or power generation.The high carbon coal is more dense than the high vol coal,and the higher vol coal will therefore weigh less by volume,due to its higher vol,or gas content.So,if you want heat,you will get more from the higher vol coals.As the coal fields are laid out,the higher carbon coals are on the east end of all the fields and as you move west,they become higher vol,this goes for all the veins.These are geological facts.When we sell coal to the steel industry,we are selling carbon units per dollar,and when we sell to power plants or for home heat ,we are selling btus per dollar.Don't believe old wives tales about needing any amount of bone or wood or impurity of any kind.

So what you sell to the steel factories is the same coal as the coal you sell to the home owner?

Fifthg, would you know if Harmony was so light, and also so well regarded for its heat, due to its high carbon content, or was it actually favored (as well as being light in weight) due to lower carbon content and higher volatiles? I.E., what made it so good and at the same time so light in weight? How did it rate for contaminants such as bone (slate)?

The steel mills will be happier with higher carbon coals,from the east,like Lehigh,and the home owner will like the western coals,like Harmony's higher vol coal.Harmony coal was both low ash and high vol,great for home heat.Blended coals and coals mid-field tend to keep everyone happy.Also,ash fusion temperature governs clinkering,which is when the ash fuses,or melts.This has nothing to do with coal purity.Certain veins have a tendency to clinker more than others.The orchard vein comes to mind,but It does not always clinker.It too,seems to be a regional thing.

There is lots of anthracite in Alaska, Alabama and Colorado too,
not that its big deal.

SO much of this depends strictly on the amount of vegetation that
rotted into the ground during the period before the dinosaurs waddled
across Pangea/Gondwanaland etc.

From what I remember there is a coal mine in PA that has a dinosaur foot print
that turned to rock from the surface mud from when a dinosaur walked through the area
while the coal was becoming coal during the carboniferous period.
.

I can tell you this much, we test our coal daily, and when the highest carbon lowest ash coal runs through the bagging plant there is a noticeable amount more coal in the bags...

Lower ash coal is less dense whether it is lower ash high carbon or lower ash high vol,because the high ash material is not coal at all.High ash is never a desirable component of coal,it is an impurity.

Also remember that different layers in the same coal seam can have different density's....normally not alot, altho on one mine I was on (admittedly bit coal) the difference in weight between the dense coking coal and the coal that was used for carbon filters was about 20%......very very noticeable when you picked up two lumps of the same size.

Of course there are different densities within the same vein, but the bottom line is the carbon is what burns and creates BTU. Last week we ran on day 90.3% fixed carbon, 3.8% volatile's and 5.9% ash, the next day we ran 89.67% Carbon, 3.93% vol and 6.4% ash and even with those slight variances there was a difference in the amount of coal in the bag to get the same weight..

Carbon burns and volatile gasses burn.Higher vol coal has higher BTU value,derived from the volatile content,than an equal ash,but higher carbon coal.That should help explain the point."Just the facts,Ma'am"

LehighanthraciteMatt wrote:Of course there are different densities within the same vein, but the bottom line is the carbon is what burns and creates BTU. Last week we ran on day 90.3% fixed carbon, 3.8% volatile's and 5.9% ash, the next day we ran 89.67% Carbon, 3.93% vol and 6.4% ash and even with those slight variances there was a difference in the amount of coal in the bag to get the same weight..

Your numbers add up to 100% in each case.Therefore, something is wrong with the numbers.For example,Your test numbers will add up to 100% in the test when all components are included,sulfur is not in your result.That would be a reduction in your total carbon number.These are not real numbers you posted.This would not make a big difference in burning,but would be more factual.

the sulfur in coal is part volatile part as, they don't account for the overall numbers our sulfur in each sample was 0.5 and 0.47 % but that number fits into part volatile material part as. one of those samples was independent from Cardan Laboratories, not on site....