MC: 1.7.10
Forge: 10.13.4.1624
Mods: GT-6.14.21, IC-2.2.827x, NEI-1.0.5.120, CodeChickenCore-1.07.48
A solid fuel burning box is not being extinguished while it is blocked by any solid block.
The only way to do it is to use an extinguisher.
THAT IS A FUCKING HUGE GAME-BREAKING BUG
I also tried GT6U and it yields the same result.
Well, actually it is being extinguished in around 1 minute after blocking it, I had tested it a few times.
But a liquid fuel burning box is extinguished instantly.
Burning boxes will be extinguished after current fuel is burned out. Liquid or gas fuels often have only a few ticks, so it just look like extinguished instantly.
Where could I find that out? It is not obvious imho.
Actually I’m heard from others,so I’m not sure about this.
big brain energy from this post 
Burning Boxes only check for Air right before consuming a piece of Fuel. So the larger the Burn Time of said Fuel you are using, the longer it takes for the Box to extinguish.
The easiest Solution to this is turning your Coal Bricks into Nuggets before burning them inside the Box, or using a different shorter burning Fuel.
And yes you can just handcraft Coal Gems into Coal Bricks, which might be more convenient for the Nuggets, and can also be placed in World!
As for that Post I just quoted:
Don’t just do that to new people!
But hey, at least I found out that a lone Smiley on one Line is being increased to twice the size, so you are getting away with it this time. 
It’s actually up to three emojis with no non-emojis on one line:
I recommend using a mortar to grind your coal to dust, and then use small or tiny dusts to power the burning box.
As to recommended reading, I suggest:
The crucible is the single biggest automation target in the game, so it can be very nuanced.
I would be using liquid fuel burning box for smelting as anyway I need to get rid of creosote from my coke oven. Whole coal is nice for things like heating boilers.
