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Technical Cement Forum / Carbon floating problem with fly ash based cement

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Raju Verma 28/01/2014 11:54:29

Carbon floating problem with fly ash based cement

Dear Expert !

We are facing a problem with black particle floating issue for fly ash based cement.

Plant is using fly ash ~ 30% in PPC cement and fly ash with LOI varies from 2 to 8%. When fresh concrte is made black particle is floated on the surface. Floating particle is collected and analysed with PSD of <5 micron.

Cement PSD ( 3 to 32 micron is around 58 to 60%) with 5 micron passing PSD is around 10%

Plant has to use this fly ash only due to availability and cost reason.

Please guggest any suitable solutions for this.

Thanks & regards

Tushar

Ted Krapkat 31/01/2014 01:39:10

Hello Tushar,

There are several ways to remove carbon from flyash so that it is suitable for use in cement or concrete;-

1. Pretreat the flyash by heating in a fluidised bed to burn off the carbon. (Energy released by the burning carbon may be recovered from this system and used to offset the cost somewhat)

2. Remove the carbon using a froth floatation system. (This requires the drying of the flyash after carbon removal.)

3. Remove the carbon from the flyash via an electrostatic extraction method.

All of these methods are expensive and require specialised equipment, but there is no cheap way to effectively remove the carbon from high carbon flyash.

You may have to consider an alternate source of flyash or paying extra for a lower carbon flyash.

Regards,

Ted.

Raj Sahu 31/01/2014 05:05:49

Please see the attached article on technological options for the separations high LOI Flyash.

Attached files

Separation_high LOI_flyash.pdf

Raju Verma 03/02/2014 13:11:57

Thanks Mr. Ted and Mr. Sahu for your suggestion

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