prawn_86
Mod: Call me Dendrobranchiata
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- 23 May 2007
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Hey geo's - I see this thread has fallen silent for awhile which is a pity as much was learnt via the excellent contributors.
I have a coal question which may or may not belong on this thread but anyway -here goes. What does it mean when a coal deposit has a high ash content? Is this an issue for a thermal coal deposit. I know that it is not great for coking coal.
Would appreciate anyone's feedback on this.
Cheers
B'man
Thanks guys- perfect.
So if I have interpreted this correctly, the higher the ash content, the lower the carbon content, and the less efficiently the coal will generate heat when it burns (or something along those lines).
So for high volume, lower energt type uses (ie electricity generation where you produce steam at boiling point of 100 degree), you can medium ash content thermal coal. Then for uses where you need very high heat transfer (ie steel production), you need high carbon-content coking coal.
Reason I asked is that REY have a massive +1 billion tonne potential thermal coal deposit but it has medium ash content. So it is fair to surmise it will not be suitable to steel making but should be ok for electricity generation (in Canning basin so will be shipped to India).
Thanks guys- perfect.
So if I have interpreted this correctly, the higher the ash content, the lower the carbon content, and the less efficiently the coal will generate heat when it burns (or something along those lines).
So for high volume, lower energt type uses (ie electricity generation where you produce steam at boiling point of 100 degree), you can medium ash content thermal coal. Then for uses where you need very high heat transfer (ie steel production), you need high carbon-content coking coal.
PS: yep this thread is great esp for us 'try hard' weekend geologists!!
Hey Bushman, yes ash content is important as its rubbish and has to be disposed of.
Us anthracite burners over here consider ash greater than 10% as crap coal but if you were to compare it too many brown coals (NSW/Vic) than thats as pure as the driven snow.
A significant proportion of ash (Silicates or sand being common, clay if brown coal) is also Iron products particularly iron pyrites (fools gold).
As a rule of thumb 1 tonne of coal will give 5 tons of steam or 2.5MW (in generation).
As to boiling at 100deg C thats only your kettle
Boiling point is governed by pressure not temperature (atmospheric pressure being 101 kPaA) and generators usually make steam from at least >12MPa. The site I'm on atm will be sub-critical @ 17.8MPa and places like Kogan Creek in Qld run critical @ >22MPa (critical being when water and steam exist in the same phase).
Carbon content is all important in coal as the heat (energy) from combustion comes from the chemical reaction converting carbon to CO2.
Hence gas produces less CO2 than coal as its hydrocarbon is dominated by hydrogen not carbon.
Yes theres a lot of coal in the Canning also.
What are you studying btw DJ ?
We can never have enough rocklickers imo:
Can anyone tell me how 1970`s and 80`s 2 dimensional seismic can estimate 2 billion barrels of oil in a 21 km by 21 km area?
It is okay if no one can, I understand the difficulty of making such an estimate.
Reason I asked is that REY have a massive +1 billion tonne potential thermal coal deposit but it has medium ash content. So it is fair to surmise it will not be suitable to steel making but should be ok for electricity generation (in Canning basin so will be shipped to India).
Bushman,
If you look through some of REY's data, try and find out if they have done any preliminary testing on the coal. Apparently, rather important parameter (among several others) will be the mositure content, which is also related to the volatile content and naturally the energy released during combustion. Coal with a moisture content above 15% would be of questionable quality.
Almost all thermal power stations are set up to accept coal of a specific blend, ie. a particular moisture and ash content, or else the coal can wreak havoc with equipment such as the injectors in the plant. So in terms of marketing and selling the product, it may require blending with other coals to reach a certain "composition" before export.
So this is quite a different scenario compared to talking about coking coal used for making steel.
Hope this helps.
jman
Hey DJ,
I'm presently on a site where Griffin Energy are building two 208MW coal fired boilers.
So is it geology that your studying?
J
Yeah studying Exploration Geology and Geophysics majors. Want a job with the big boys when I have finished the degree.
Thanks for the extensive input everyone , interesting topic. Could someone please help me establish a fundamental framework so that I can work towards a realistic valuation of a mining stock .
I can appreciate there are alot of variables and cross market considerations involved in such an estimation so I will outline some figures and general estimates in the hope of learning a few things.
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