I am presently working in a cement company in a senior management level in technical services and very much interested to know about the process involved in producing white cement based wall putty and the steps of testing its characteristics. One company here in India makes this product very successfully.

I'm afraid I don't know the detail of how that particular company make their white cement wall putty. However, it must involve mixing the white cement with a solvent which prevents the hydration of the cement. Boiled linseed oil is commonly used with glazing putty. When applied to the walls this solvent carrier evaporates allowing the white cement to hydrate and slowly harden.

We are white cement manufacture in India. Presently we are facing the problem in clinker-quenching problem at out let of Rotary Decoloriser (Clinker quenching cum dryer). Our plant was originally design on 100 per cent oil fired (LSHS/RFO) but currently we have replaced fuel from oil to pet coke. Now we are using 90 per cent pet coke & 10 per cent oil in kiln. Due to using the pet coke the we getting very poor clinkerisation and most of 90 per cent clinker comes in dust form and the balance 10 per cent is clinkerisation. As in Decoloriser we are having the 4 nos. water nozzles consisting of water flow control valve & flow meter for measurement of water flow. For controlling we have PID controller between steam temperature V/s flow control valve. In this PID as & when steam temperature changes corresponding the position of valve also change but after using of pet coke we observe that change of steam temp is very frequent due to dusty clinker hence we are unable to control uniform clinker temperature.

I am familiar with the need to quench the clinker for white cement production. Also with the operation and control of such quenchers. The poor nodulisation of the clinker will be a consequence of the sulphur content of the pet coke you are using to fire your kiln. Have you tried to increase the fluoride content of the clinker to combat this effect? Regarding control of the water flow to the quencher. I would discontinue the use of the PID loop which has the steam temperature as its controlled variable and water flow control valve position as manipulated variable. The water flow can be adjusted in direct relation to the clinker production rate (feed rate) of the kiln. However, steam temperature must continue to be monitored to avoid condensation in the quencher exhaust ductwork and dust collection cyclones. The appropriate water flow for a given feed rate to the kiln must correspond with a flow that ensures the steam temperature remains above the dew point all along the exhaust gas flow path.

Hot clinker is quenched in water losing useful heat, can you syggest heat recovery without altering process of quenching.

The white cement clinker must be quenched as it falls from the kiln to freeze the clinker minerals in their high temperature form. However, this quenching does not need to be to ambient temperature or anything like that. 600 degrees C is sufficient. Therefore quenching in water sprays to this temperature, leaving some sensible heat in the clinker is possible. However, how much useful heat could then be recovered from the clinker is debatable.

We have recently conducted some raw meal burnability testing on samples with varying residue and C₃S. Results showed little dependence on these two variables. Following further investigation I was told burnability can be highly dependent on 45 micron insoluble residue. What are your thoughts on this? I am still reluctant to believe the low dependence on C₃S because in the kiln I am still observing significant fuel variations with changing C₃S.

The classical burnability index takes into account both the chemical composition (i.e. LSF, C₃S etc.) and also the fineness and mineral composition of the kiln feed. The theory is that large quartz (SiO₂)grains and lime (CaO) grains are very difficult to combine in the kiln, and this is fairly well established. You can get the formula from the proceedings of the IEEE 2002 in Jacksonville.