We are having Polysius design ILC six-stage kiln have dimension of 3.8m ID and 64m length. We are firing 100 petcoke in both main firing and calciner firing. We are facing problem of reduction in output and percentage of fines generation in clinker increased.The kiln feed and petcoke chemical analysis are as under: SiO₂ 13.80 - 14.10 Al2O₃ 3.6 - 3.75 Fe₂O₃ 3.4 -3.6 CaO 42.7 - 42.9 MgO 0.7 - 0.9 SO₃ 0.1 -0.16 K₂0 0.28 - 0.35 Na₂O 0.10 - 0.12 Cl 0.06- 0.09 Petcoke Analysis C 88.5 - 89.5 H₂ 3.8 - 4.2 S 6.0 - 6.5 Violatile Content 9.8 -10.4 Calorific Value 7960 - 8020 Kcal/Kg Coal Ash Content 0.30 - 0.70 Please suggest suitable counter measures to increase throughput rate and stable running of kiln.

Unfortunately these problems are regularly reported on kilns burning petroleum coke. The problem is caused by the sulphur content in the petroleum coke. This has the effect of reducing the viscosity of the flux and this leads to the increased fines generation in the clinker. You must ensure that you have good oxidising conditions in the burning zone to minimise the recirculation of sulphates. After that you need to change the chemistry to adjust the viscosity of the flux. Increasing the Al₂O₃ content may help, but perhaps the best solution would be to add some calcium fluoride to the kiln feed.

What would be the recommended ball charge and combination to produce masonry cement at 6000 cm²/g. the component percentage are clinker= 50 per cent, limestone=45 per cent, gypsum=5 per cent. I tried researching on this, but the suggested ball charge and combination would always refer to OPC at 3000-3200cm²/g. We are still in the process of rehabilitating an old cement mill, and except for the ball charge, the mill internals are in good condition. What frequency of axial tests would you recommend? We intend to start the tests at 85 per cent ball charge.

I am not surprised that you could not find what you were looking for by research. You will have to find the optimum ball charge for your particular mill making this masonry cement by a series of axial tests while charging the mill to 100 per cent media loading. The only thing you can predict is that you will need a much smaller overall ball charge due to the high fineness you require and the easy grindability of the limestone. I would start the axial tests at a lower filling degree. Probably 60 per cent. If you leave it to 85 per cent you might not be able to correct the total charge to the optimum with the remaining 15 per cent.