re Raw mix adjustment for courser quartz and calcite

Mr. Ted rightly pointed out that your C3S content indicates that free lime in the clinker is around 2-3%.Coarse quartz particles seems your main concerns.Coarse quartz coming in your raw mix is either fom limestone or corrective material used for silica correction.The possible ways to reduce quartz content in raw mix are, i) If a high content of the hard quartz particles must be reduced,separate grinding may be necessary. ii) Alternative Silica corrective material should be examined.Different sands may have identical chemistry but different sizes of quartz.

If high quartz material could not be avoided then Separate grinding of quartz beraing material will be necessary.However,separate grinding require more energy and capital investment.

Advantage of reduced coarse quartz particles:

1. Easier to avoid big C2S clusters.

2.Will normally improve clinker grindability.

Please examine the kiln feed, % Quartz and Calcite on +45micron and +125 micron by Optical Microscope .Recommended value of minerals in the Kiln Feed: Calcite +125µm - <3%, Quartz +45µm - <9%.

Please also check the possibility if you can reduce your raw mix residue on +212 micron  to zero.

Regards,

Raj Sahu

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re Raw mix adjustment for courser quartz and calcite

Dear Mr. Ted and Mr. Sahu

Thanks for your input.

Plant normally measured KF slurry residue on 212 micron. For filtration , - 5 micron is very crucial for and plant tried to maintained not less than 20 – 22 %. Residue on 45 micron is maintained around 50 to 55%.

Plant is using Laterite as flux material along with limestone. No silica correctives are being added. Quartz content is low in Laterite.

I rechecked the C3S content as per following formula and C3S is coming ~43 with average free lime content 2.8 to 3%

C3S = 4.07 (CaO-F.CaO) – 7.6 SiO₂ – 6.72 Al₂O₃ – 1.43 Fe₂O₃

Plant does not have margin to increase LSF in limestone. Pet coke usage is just started and under stabilization stage.

As SiO2 in KF is in higher side around 13.5, reduction is SR further is too difficult. Consistent usage of pet coke will help to reduce SR.

Present Raw mix

SiO2 ~ 22.4 , Al2O3 ~ 5.3, Fe2O3 ~ 4.1 , CaO ~ 64.7 , MgO ~ 0.68 , Na2O  - 0.26 , K2O - 0.6 , SO3 ~ 0.6 , Free CaO ~ 3.0 , LSF ~ 90, SM ~ 2.4 , AM ~ 1.31 , ASR ~ 1.22 , C3S ~ 39 , C2S ~ 34.8 , C3A ~ 7.2 , C4AF ~ 12.3

Proposed raw mix

SiO2 - 22.2 , Al2O3 - 5.8 , Fe2O3 - 3.7 , CaO - 64.8 , SO3 - 0.85 , LSF - 91, SM - 2.34 , AM - 1.57 , ASR - 0.9, C3S - 39.4 , C2S - 34, C3A - 9.1

Please comment whether Fe2O3 reduction will be beneficial or not?

Regards

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re Raw mix adjustment for courser quartz and calcite

Have you any scope to add hydrocyclones to your wet mill circuit and reject the coarser material?

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re Raw mix adjustment for courser quartz and calcite

Hello 

In our wet grinding one part og limestone is seperated through hydro cyclone and courser part is enriched through floatation plant and finer part is directly added in KF.

Another part of limestone around 10 to 12% is ground with lateriate (flux material) and directly mixed with KF.

Mixed KF is sent to filtration plant for cake formation where kiln waste gas is used to dry cake in crushed dryer and fed to the preheater top.

Regards

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