we have 6700tpd china plant. we have high free lime now adays in our clinker our raw mill residue 13% on 90micron. coal mill residue 14% on 90micron. still on high liter weight we have high free lime aboe 2%. also snow ball formation observing in kiln. how to contro this....
Hello Armankhan,
It sounds like your raw meal is very hard to burn. This can be due to either high LSF, coarse silica or coarse calcite in the raw meal, all of which will leave excess free lime in the clinker which cannot be burned out completely, even by harder burning. Because you are burning harder (high litre weight) to try and lower the free lime, the burning zone is extending further than normal back up the kiln and these "snowballs" are forming due to liquid phase occurring in areas of the kiln where it would not normally be present.
I can only suggest that you reduce your raw meal LSF, if possible... or check for coarse silica (quartz) or even coarse calcite (limestone) in your kiln feed.
Also, have you changed fuels recently? If you are suddenly using a fuel with much lower ash and have not lowered the raw meal LSF to compensate, the raw meal LSF will be too high for the low ash fuel.
Regards,
Ted.
sir.. lsf of our clinker is 89 to 90. ash 10% in coal. we have not change our coal. still we have high free lime even on high litre weight also snow ball formation and some times cakes formation also observed in cooler but free lime high above 2%
Hello Armankhan,
Have you considered reducing your raw meal fineness?
What silica corrective do you use and how much? Do you have much coarse silica (>45um) or calcite (>90um)? Also, do you add any other alternative fuel or material streams to the kiln?
Regards,
Ted.