High SO3 in limestone used as additive

Dear All,

Compliments of the season to you all.

Please we changed our cement additive limestone source, the new limestone contains higher level of SO3, and due to this, our cement SO3 is going higher (SO3 analysis using XRF). 

Please do I need to change my Gypsum consumption to cater for this or the limestone SO3 does not take part in ettringite formation.

Please I do not have the setting time results yet (and i need to take a decision to prevent customer complaint).

Please kindly give your expert opinion with reasons.

Thanks

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re High SO3 in limestone used as additive

Please inform the concentration of volatile components content (K2O,Na2O,Cl & SO3) of kiln feed,Hot meal at the bottom stage cyclone and Clinker.After getting the volatile conent data we may suggest counterneasures in your specific case. 

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re High SO3 in limestone used as additive

Hello Haliff,

Yes, as Raj has pointed out, we would at least need to know your clinker K2O, Na2O and SO3 content. The reason is that if sufficient alkalis are present, SO3 will preferentially form alkali sulphates and/or calcium langbeinite (2CaSO4.K2SO4) in the clinker. If alkalis are deficient, SO3 will become incorporated into solid solution with the clinker minerals (particularly C2S).

If enough water-soluble alkali/calcium sulphates are produced, less gypsum may be used. However, if there is a molar deficiency of alkalis over sulphur, the excess SO3 is able to become incorporated into C2S. This would cause the C2S to become less reactive which inhibits further reaction with free lime to produce C3S, resulting in more C2S and less C3S in the clinker. This would detrimentally affect cement strengths.

From the clinker K2O, Na2O and SO3 contents we can calculate the SO3/Alkali ratio which can tell us which form the SO3 is likely to take in your clinker.

Regards,

Ted.

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re High SO3 in limestone used as additive

dear:

     S element in limestone change to SO2 from the mill to the cylclone 2. most of S in limestone are FeS2 and some organics containing S element.

     We have do some research of S's circle in cement industry.

     If you would want to discuss more details, you could cantact me.My email is xinyutatala@126.com. I work for Tianjin cement industry design and research inistiture in China.

 The attachments is S's circle in kiln in Chinses language. 

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