I can offer some help here. My basement is not set up well for coal delivery, so I have tried a few options using the leaf blower. Electric in my case, but I imagine a gas blower would move a lot more air.
First try consisted of 3" PVC, a tee with a toilet flange attached to a 5g bucket. This did not work very well at all. The 5g bucket was too small, and the 3" fitting was not large enough to prevent the coal from bridging the hole. What coal that did fall in was moved quite effectively into the bin, and some across the basement
Second try consisted of the same setup but using 4" PVC and a 19g plastic utility tub. This solved the bridging problem, and moved the coal, but not as well as the smaller pipe. More airflow would probably have made a huge difference. The 19g tub was much easier to deal with as we were using an auger to get the coal to the tub, thus controlling flow was not easy or practical.
In both cases the coal was delivered wet, and the second load was a 50/50 mix of rice and buck. Dust was a non issue since the coal was wet.
Austin Carter delivered both time, but as he has moved on in his career, the next load is on me. Thanks to the 24" of snow on the ground, I will not be able to access the one window in the basement this time around. And I will need coal shortly. So I am going to have to move the coal 70-80' from the driveway, through the bilco doors to the opposite side of the basement. I plan on using 4" PVC again, but using a furnace blower out of my old oil furnace, adapted down to the 4" PVC. I'll report back as to whether it works or not