Saprina,
It is no surprise that you find scattered values for the index.
Just consider the LSF. Clearly the optimum LSF will vary from one plant to another depending on how easy the burning conditions are. The burning conditions themselves do not only depend on the burning index but also on the fuels used or the cycles occuring in the kiln.
Note also that definitions are not well normalized and therefore, you should specifiy the definitions you are using. For example, do you take free lime and SO3 and alkalies into account in the burnability index? Personally, I use regularly a certain burnability index, but I have never paid attention to a "burnability factor".
Similarly, what would you call the "liquid phase at the burning zone"? Do you mean the physical value (difficult to know)? Do you mean the standard Lea definition? Would you include the SO3 and alkalies just for stoechiometry or with the full physics of liquid formation? I even think that the actual thermodynamic data are not well known and I am always surprised to see such data available in "standard packages" like mtdata.
The same discussion would apply for the minimum burning temperature. 2% free lime shifts that by about 40°C. And the formula you propose does not take the cycles into account which therefore leads -in principle- to different objectives for different plants.
Your question is quite interresting, but I have difficuty to give a clear answer, except to say that for many reason these data should be very dispersed indeed.
