Determination of FeO content in Clinker

Dear Ted,

I  would like to know the procedure for determination of FeO in Clinker. I am aware about the magottaux method of ascertaining the reduced condition which is a conformatory test, but i would like to know by chemical wet analysis the % percentage of FeO.Also let me know if there is any detrimental effect of the presence of FeO in the Iron Ore.

Regards

Arvind

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Re: Determination of FeO content in Clinker

Hello Arvind,

1. There are a multitude of methods for the wet-chemical analysis of ferrous iron, but few of them are simple. The reason for this is that FeO is very easily oxidised during the typical sample dissolution stage.

 However, I have located this method through research on the web;-

http://www.minsocam.org/ammin/AM70/AM70_961.pdf

It may be of use to you.

2. Because of the highly oxidising conditions present in the kiln, the oxidation state of the iron in the raw materials is not usually an issue. Even elemental iron (such as in tyre wire) will oxidise to Fe2O3 under normal kiln conditions, if it remains reasonable finely divided.

The FeO content in iron ore should not be a problem. Indeed some plants have used  magnetite (FeO.Fe2O3) as their iron corrective, without the slightest detrimental effect.

Regards,

Ted.

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Re: Determination of FeO content in Clinker

Dear Ted, Thank you for you valuable inputs. Will there will be a fluctuation in the LOI of Kiln feed due to presence of FeO and secondly as per your experience what would be the FeO content in the Clinker when it is under reduced conditions.

Regards

Arvind

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Re: Determination of FeO content in Clinker

Hello Arvind,

Whether or not there is a significant change in kiln feed LOI will depend on the exact amount of any increase in FeO content in the kiln feed.

For example;-

FeO reacts with O2 upon heating to form Fe2O3 by the following equation;-

2 FeO + 1/2 O2 = Fe2O3

Therefore, from the molecular weights;- 143.7g FeO + 16g O2 will produce 159.7g Fe2O3

This means that FeO has an "LOI" of (146.7-159.7)/146.7*100 = -11.1% (actually a Gain On Ignition of 11.1%)

So, if we increase the FeO content of the kiln feed by 1% (while keeping the LSF, S.R. and A.R constant) we will reduce the LOI by (1/100*11.1) = 0.11%

ie. 0.11% drop in LOI for every1% increase in FeO for the same kiln feed chemical moduli.

To answer your second question;-

Due to the active promotion of an oxidising kiln atmosphere in most well-operated kilns, I have never come across Fe+2 levels in clinker more than about 500-800ppm in normal grey cement kiln operation. This is why you need a very sensitive test (Magotteaux) to detect Fe+2 in clinker. 

However, I'm sure it is possible to produce clinker containing much more Fe+2 if the reducing conditions in the burning zone are very exceptionally strong (eg burning coal impinging directly on the clinker bed)

Hope this helps,

Ted.

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