We are facing severe problem of balling ball size is sometimes around 2m dia which chokes the hammer crusher and we are forced to stop the kiln. What are the possible reasons form such big balls, how is a kiln operater responsible for this, how a kiln operator can avoid such balls through process changes, how we can avoid the balls by changing the chemical composition of kiln feed.

We hear of these problems with increasing regularity. At one factory the problem was associated with an increase in the Mn₂O₃ content of the kiln feed associated with one of their additives. There are also instances where an increase in the MgO content of the kiln feed gives rise to balling problems. However, the most likely cause is a difference in the clinkering range of the material in the kiln brought about by variation in the sulphate content. A heavy coating tends to form and the material is then dammed behind this coating and agglomerates into a large clinker ball. You must ensure that there are good combustion conditions in the main burner of the kiln to minimise the recirculating sulphates. The other process response is likely to be an adjustment in either the alighnment or the primary air supply to the main burner of the kiln. Regarding the chemistry then any changes which adjust the liquid content will change the clinkering range in the kiln. Addition of calcium fluoride to the kiln feed is also helpful.

I am working on a project for my university studying the different technologies used in the cement production process from different companies, and I would like to know if any corporation has already constructed its process with a fluidised bed cement kiln for commercial operation and could reach acceptable efficiency. Also, I am researching for the system with most number of steps at the preheater, and the performance of the process compared to other ones.

I am not aware of any commercial operations using fluidised bed for industrial cement clinker production. There are pilot and research installations but not of commercial capacity. There are number of kilns with six-stage preheaters. This brings the exhaust gas temperature down to less than 300 degrees Celcius. However, the most economic number of preheater stages is usually five as increased capital costs for six stages cannot be recovered by the energy savings. A company might choose a six-stage preheater if there is a shortage of water for exhaust gas cooling and conditioning. Therefore most of the existing six-stage preheater kilns are in desert environments.