Normally the difference in LOI between kiln feed and hot meal is used to determine the calcination degree... but there is a catch in that simplistic approach. The problem with using simple LOI differences to measure calcination degree is that the LOI test overestimates the real LOI in hot meal and therefore underestimates the calcination degree.
This is because, at the temperature of the test (950 degC), alkalis, chloride even sulphur in the hotmeal are also partially volatile, causing the LOI of the hot meal to be 1-2% higher than the real (CO2) LOI. Considering that the usual range of LOI of hotmeal is 2-5%, this loss of volatiles represents a large error.
To allow for these volatiles, the following calculation should be used:-
LOIkf / (100-LOIkf ) – LOIs / (100-LOIs )
C = ------------------------------------------------------- * 100
LOIkf / (100-LOIkf )
CD = % calcination degree
LOIkf = LOI of kiln feed.
LOIs = LOI of hotmeal (bottom cyclone) sample.
re Re: Pre-Calcine
Dear Ted Sir,
You have explained very correctly on Degree of Calcination.
But my Question or said my problem is that How to measure correct LOI of Hot meal Sample,precisely saying Hot Meal is highly Hydroscopic material
1.After Taking sample from sampler Point it has to be kept in desicator for cooling then weigh or by kept in oven for 10 min then in disicator & then weigh it.What is correct step for it.
2.If Kiln is disturbed for dustyness from Quality point of view what we have to check like Raw Mix , Coal Ash,Precalciner Temp is correct or not i.e Hot meal DOC
3.How to measure effiiciency of PreHeater