What is the fire point of sucrose with an average particle diameter of 60 micrometres?
I managed to find the answer in the MSDS of sugar given by the US Department of Labour, after some searching.

In the MSDS found here there is an ignition temperature (which I imagine to be the same as the fire point) of 350 C, with a minimum explosion concentration of 0.045 g/l in air. There also seems to be a possible ignition from a dramatic increase in pressure (mentioned in the MSDS to be 5,000 psi/sec), though no further dangers are expressed.