I have a friend that makes furniture. He gives me big bags of material that is bigger than sawdust, small than shavings. It isn't good for any purpose he has, so he gives it to me and I use it as brown material in my compost. He just gave me 6 big trash bags full. I was going to make a batch of charcoal for biochar this morning. I was going through my scraps getting pieces to fill the retort, and partway through filling it, I remembered the new stuff I just got. It's nearly all hardwood, and if it chars well, it's the ideal size for biochar, no crushing necessary. I filled the retort the rest of the way with the wood pieces. The batch is done now, but I won't open the retort until tomorrow, so I'll update with the results then. I'm very excited to see if it works. If it does, I have a great use for another waste stream, and the end result will be ideal for my use. Crushing charcoal isn't hard, but it takes time, it's messy, and it's dusty. The results are not nearly as uniform as this will be. I guess we'll all know tomorrow.
I'm currently using similar material for my "inside our wood-stove" retort, only mine is cedar shavings from a fellow's back-yard sawmill. I'll be sorry when it's gone as he's passed on (of old age - we all have to go sometime). The material chars well and the stuff that doesn't got into mulching the ducks, I've been mixing with various goodies, letting it sit a few days, and then adding it to raised beds.
I expect your experiment will go well and I'm really glad you're turning a waste product into value-added biochar!
I'm very happy with the way this charcoal turned out. It leaves no stains on your hands at all. The size and consistency is very good. I won't use this exclusively because I want some pieces of larger size, but the quality of this batch is excellent.
This summer I plan to experiment more with pit and trench charcoal making. I've played with it a little in the past, but the quality of charcoal from my retort is so much better, I can't get away from it at this point. It may be that I use the retort in the future for this very small stock and another method from larger things. The quantities from the trench /pit methods appeal to me if I can hone my technique to the point the quality is at least in the ballpark of my retort made charcoal. The adventure continues.