butchs37 wrote:Ok coal berner maybe you can help me out on this I can understand the fly ash issue but how does adding bone give you more burn time? I can see how it might on a hand fired but cant understand how it can on a stoker.
Being bone is formed in the coal & with the coal it as a small % of Carbon in it and it does burn to a point but not to a
ash being it is harder then coal and does not burn up all the way like pure coal does it will hold heat keeping the fire hot longer hence holding the fire longer . The State & Fed Anthracite standard's book for sizing processing & Rules & Regs for coal shows the charts and it states that the coal Processing Companies can use up to 3% slate & 4% bone in with the coal.
and most of the breakers will add or keep in a small amount of both Just to help keep the ash content up so it will burn
better and give heat . There is a cut off on coal ash content being to low to burn meaning it burns to fast & Having to much fly ash usually it is 5% or below but it will also depend on the Vein of coal & if it is White Ash or Red ash .
That's why you will see the bigger coal Companies / Breakers mix there lower ash coal with higher ash coal to get the right or a good % of ash content .
Now with all this said I prefer myself low to no bone in the coal I burn and I prefer Red ash coal with low ash content 6.5 to 7.5 % over White ash coal for the heat value being most of Red ash coal has a higher btu value content then white ash coal does.
And like you said this has a lot more to do with Hand fed stoves Furnaces & boiler's holding fires on a natural draft
Then it does with Stoker stoves Furnaces & boilers . But it does benefit both maybe a little more with Auto stokers using combustible Fans that create more draft that may have Problems with to much fly ash build up in the stack pipe creating a draft issue Using to low of a ash content percent coal