Anyway, managed to fix the LaTEX mess from jakuub's link and this is the formula for the particle size where:
x_m = mean particle size (cm)
A = rock factor,
K = powder factor (in kg/m^3)
Q = mass of explsovies (in kg)
RWS = relative weight strength of the explosive (Apparently blastex is used and its RWS is
0.84)
X_m= A*(K^-0.8)*(Q^0.167)*((1.15/0.84)^0.905)
Once you figure out your powder factor AKA mass of explosives multiply it with blastex's energy density of 740 cal/g or 3098232 J/kg of explosive used per cubic meter (I used
this converter to convert from cal/g to joule/kg).
Rock factor and powder factor are apparently set and the mass of explosives is also apparently the same as powder factor.
Some powder factors
here (Or just use the average of
0.75 kg/m^3 here, the other link gives almost equal values AFAIK but using separate rocks is better IMHO).
Though I should note that this doesn't work for stuff that isn't stone. AKA you can't use this for metal or wood. Rock factor is within
7-13.
Some more details about the Kuz-Ram model
here