Why is there sulfur in coal? Coal is ancient plant material. I didn’t think plants had that much sulfur in them.
This list is for the human body, but I imagine any other living thing on Earth has a similar coposition:
Oxygen (65.0%)
Carbon (18.5%)
Hydogen (9.5%)
Nitrogen (3.2%)
Calcium (1.5%)
Phosphorus (1.0%)
Potassium (0.4%)
Sulfur (0.3%)
Sodium (0.2%)
Chlorine (0.2%)
Magnesium (0.1%)
Iodine (0.1%)
Iron (0.1%)
Chromium (trace)
Cobalt (trace)
Copper (trace)
Fluorine (trace)
Manganese (trace)
Molybdenum (trace)
Selenium (trace)
Tin (trace)
Vanadium (trace)
Zinc (trace)
So, about 3 grams of every kilogram is sulfer. And since most of the water is out of the coal by the time it’s mined, that percentage would be higher.
Sulfur comprises a significant amount of plant material. Coal is old plants.
AWD - perchance, would there be an internet link to that reference? thanks
Uhhh…define most. Many power plants burn lignites that are upwards of 50-60% moisture by weight.
Do you know just how lucky you are? This gal is an acknowledged World expert on coal and coal power plants, and just looooooves to talk about them!
Paraphrasing from the DOE Clean Coal Technology Report, the Combustion Engineering “Combustion Fossil Power” book, and Babcock & Wilcox “Steam”, and my 8 years of experience:
The sulfur in coal is the legacy of mineral deposits in sea or brackish water. Trapped inland by the land-mass upheaval, the seawater formed vegetation-rich primordial bogs, that when they evaporated left behind coal deposits.
Where fresh water was present during the “coalification” period, less sulfur is present in the coal. Where saltwater or brackish water was present, more sulfur is present. Because of the land structure of the Western US, most Western coals thus have much lower sulfur contents than Eastern coals. And Midwestern coals vary between the West and East overall. Wyoming Powder River Basin coals typically have a sulfur content of 0.3 to 0.6 %, while Eastern coals can be as high as 1.5 to 2.5%, or even much higher (I’ve seen 11% at one mine!)
The following is important - sulfur exists primarily in 3 forms in the coal:
Pyritic (sulfide ion): This is where sulfur is combined with iron in finely dispersed particles that are physically distinct from the coal. These particles can also form large pyrite rocks or crystals, and be as large as up to 2 to 3 inches across (I’ve got a bunch of them on my shelf right now in front of me). A coal plant with proper seperation equipment or washing equipment can remove a lot of the pyrtites, and thus a lot of the sulfur, but at a significant cost. This sulfur sometimes appears as the mineral marcasite also.
Sulfates (sulfate ion): This is where the sulfur is physically distinct from the coal, but the ions are sulfate ions, instead of sulfide ions (as in pyrites or marcasite). These are normally a very small part of the coal, except in Midwestern US states, where they can contribute as much as the Pyrites do.
Organic: This is where the sulfur is actually chemically bound to the carbon atoms in the coal structure. This sulfur cannot be practically removed in standard coal plant operations, but it can be removed in the case of Coal Gasification.
And yes, there is an exception. Very rarely elemental sulfur can occur in coals, but this almost never happens.
Most of the sulfur in coal is the Pyritic and the Organic types. In some coals, the pyritic sulfur can account for as much as 70% of the total sulfur, in others it amounts to as little as 5-10%. When combusted, both types of sulfur are released to form SO2 (sulfur dioxide), which is of course a major component of acid rain.
Any questions? 
The pyritic type sulfur found in the coal…is that where the “clunkers” come from? The town next door is home to the “largest fossil fuel power plant in the east,” and I know quite a few of the workers there. They’ve talked about chunks of iron that they call “clunkers” that bind up the coal pulverising equipment. Apparently its a big enough problem that there’s a large metal detector on the conveyor belt that will either cause the clunker to get tossed off the belt, or will shut down the whole belt if it can’t be removed. Are the clunkers from pyritic sulfur deposits, or are they just lumps of iron that are sitting in the coal seams?
See…I can kind of talk power plants too… If you ever want to know about cable tray fires, I’m the guy to talk with 
Well, the answer is most likely none of the above. You may think it’s for pyrites and iron, since pyrites are often referred to as para-magnetic, which means they can be removed in a strong enough magnetic field. However, while pyrites are abrasive and do cause greatly increased wear over the long term, they are not the primary concern for the pulverizers (mills) as they can be ground. The primary concern is what is often referred to as “tramp iron”, which is actually broken pieces of mining equipment, rail equipment, coal yard equipment, and general garbage that are shoveled in with the rest of the coal. After all, the plant is paying by the ton…
You may wonder just how much tramp iron winds up in coal. Well, the answer is - sometimes a lot. I have stood by pulverizers and seen large pieces of iron go flying out on a frequency of once every 10 minutes or so. This tramp iron specifically consists of such things as blades, ball bearings, wire, swing hammers, gears and gear teeth, bolts, railroad spikes, nuts, etc. Sometimes even whole sections of railroad rail! These can seriously screw up a coal mill if not removed or rejected by the mill.
I also know of a couple plants that found dead bodies in the coal, from a different sort of “tramp” who froze to death while riding in the coal cars. Ugh.
Of course, if you have a ball tube mill, then you don’t care quite as much about tramp iron - anything that goes into a ball tube mill comes out as dust from the other end, whether it’s coal or railroad spikes. The metal may screw up the equipment that transports the coal to the ball mill, so it’s always best to remove it.
I have to admit - I’ve never heard the term “clunkers”, always just “rejects” or “tramp iron”. Now “clinkers” are what they call the large pieces of slag that drop from the boiler waterwalls and suspended tubes and go clanging off of the bottom of the boiler, so I’m sure they’re not referring to that.
What is the name of the plant you are nearby? It’s likely I’ve been there…
Oh! I just figured it out - you must mean Brayton Point, correct? I’ve been there a couple times…
Shoot! Brayton Point is big (1600 MW), but Mt. Storm WV (1662 MW), Paradise KY (2558 MW), Cumberland TN (2600 MW), Mansfiled PA (2741 MW), Keystone PA (1872 MW) etc. are all bigger. But it depends on where you define “East”
I’m impressed…Brayton Point it is. Although, since PG&E bought it, now its called “Somerset Station” or something like that. They’ve billed themselves as the largest plant in the east for years…maybe they mean “northeast” and just say east to boost their collective egos.
We’ve got the Montaup Power Plant in Somerset also, but I’m sure you already knew that. Nothing of note about that one, though.
And just for laughs, a picture I snapped at Brayton Point a year or two ago. This was the first time the plant had been 100% shut down since they opened back in the mid 60’s. There’s something unsettling about seeing the outgoing cables from the generators all burning together. Think of welding on a grand scale. 1000lbs of dry chem didn’t even make the fire blink. Scary stuff, but not as scary as the line we got very nonchalantly from the plant operators: “we don’t know if it completely shut down, so be careful.” Gee, thanks, a gazillion watts might be flowing through here, I’m about to pour some water on it, and you tell me to be careful? You power plant people must have rocks in your heads to deal with that much electricity on a regular basis
This is true, they are often very “odd” about determining if the electricity is on or not.
You know, I’ve walked down I don’t know how many power units , from Arizona to Italy, and one thing always strikes me: I have no trouble walking past shaking pipes carrying 2600 psia 1005 F steam, which would cut me in half if a pinhole leak developed. I have no problem standing on top of a CE 1103 mill, which would blow me clean through the roof if it decided to have a “puff” at that point. I was sucked up against the inlet grating on a 4000 hp Forced Draft fan, and had to inch my way off of it. I’ve walked in every dangerous spot in the plant that doesn’t require a bunny suit, and still the thing that creeps me out is the sound of the electrical corona from the primary switchyard - like the sound of a 100-foot angry hornet. (shudder) I hate electricity!
Yep, here it is.
Anthracite, please check out http://boards.straightdope.com/sdmb/showthread.php?threadid=38163this post