Wow, what an inferno.
That looks just like pulverized coal combustion in huge 1,000 MW utility boiler furnaces. Not a surprise because pulverized wheat is pulverized carbon, probably at the same particle size distribution.
Flour mill explosions used to be a thing.
My recollection is that you can fill the end of a straw with flour and then forcefully blow it out over an open candle to get a nice demonstration of flour’s flammability.