Dear All,
Pl.let me know if any one has carried out plant scale study on clinker litreweight vs free lime for different clinker size fraction to arrive at appropriate clinker sieve for litreweight determination.If yes,then study report may pl. be forwarded on my e-mail ID bhaskar.agate@gmail.com
Awaiting quick responce.
Regards
Bhaskar Agate
Dear All,
An article has been published in ICR Aug.10 th issue page no.70 on the subject title "Quality Control of Cliner".Looking forward to readers feedback.
Regards
Bhaskar Agate
Bhaskar:
An article has been published in ICR Aug.10 th issue page no.70 on the subject title "Quality Control of Cliner".Looking forward to readers feedback.
Hi Bhaskar,
I just read your article in ICR and found it very interesting.
The introduction to the article mentions that your study has been extended to semi-dry and dry process kilns, but I couldn't find any information for those processes in the article. Over the years, I have had occasion to perform several similar studies on both semi-dry and dry process kilns, with mixed results.
In my experience, litreweight vs freelime correlations are reasonably good for wet-process kilns, marginally acceptable for some semi-dry process kilns but almost useless for large dry-process kilns. Have you also found this to be true?
As part of such litreweight vs freelime studies I always make a point of performing a clinker microscopy study (polished section) of each fraction as well. This can help explain why some kilns regularly produce clinker that just has no useful correlation at all.
I found that large dry-process kilns are generally very 'dusty'. i.e. large amounts of clinker dust returning with the secondary air. This dust may have already passed several times through the burning zone and therefore has zero free lime content and is composed mainly of alite crystals.
The dust forms an outer coating on clinker nodules which is typically 1-2mm thick. Under the microscope, it can be seen that this layer is extremely porous and is built up from individual dust particles cemented together in a sponge-like structure by thin bridges of liquid phase (originating from coal ash melted in the flame).
At first glance you might dismiss a 1-2mm thick layer as inconsequential, but the smaller the nodule selected for the litreweight test, the stronger the influence that this type of layer has on the overall nodule density. For example, if nodules with an average diameter of say 6mm are selected, a 1mm layer represents 70% of the total volume of the nodule! Even for a 10mm nodule, a 1mm layer comprises almost half of the volume of the whole nodule. So, the influence of a very thin, low-density layer is very significant.
As a result, such clinker nodules result in a low litreweight while at the same time a low free lime content.
Consequently because of this anomaly and others (such as very hard burned high LSF clinker), the litreweight vs freelime plot of large dry kilns looks more like a shotgun blast than any sort of straight line.
I would be interested in your comments.
Regards,
Ted.
Hi Ted,
At the outset let me first thank you for your useful comments. Your microscopic analysis has added value to my understanding on the subject for which I was looking for, as I could not use microscopy tool in my case study.
Because of the limitations of number of words I could not cover the findings of Case study on Semi-dry and dry process Kilns in ICR article. However, detailed case studies are respectively available in proceedings Vol.4 of Sixth NCB International Seminar on Cement and Building Materials New Delhi 24-27 November 1998 and 8th NCB International Seminar on Cement and Building Materials New Delhi: - Paper published on “Clinker Quality Control” Authors: R. K. Saxena, B. A. Agate & Durgaprasad.)
Findings in terms of clinker size and corresponding coefficient of co relationship are tabulated for comparison.
|
Clinker size mm |
Wet Kiln |
Semi dry Kiln |
Dry Kiln |
|
- 19 + 12 - 12 + 06 - 06 + 03 - 03 |
Too big size for liter weight pot - 0.690 - 0.793 - 0.805 |
- 0.640 - 0.570 * * |
- 0.918 - 0.935 - 0.930 - 0.884
|
* Too fine clinker and adequate quantity not available for litre weight determination even after screening 12-15 kgs. Sample.
Wet Kiln – Lower the clinker size higher co relationship
Semi dry Kiln – Lower the clinker size lower co relationship; Poor corelationship in comparison to Wet & Dry Kiln
Dry Kiln - Comparatively good corelationship
Considering all the norms that are spelled out in the article the following clinker size was proposed for litre weight determination parameter
|
Kiln |
Clinker size mm |
Coefficient of co relationship |
|
Wet Semi dry Dry |
- 06 - 19 + 06 - 12 + 03 |
- 0.823 - 0.610 - 0.930 |
It is evident from the above that as we move from Wet to Semi dry the co relationship is week which is in agreement with that of your detailed microscopic studies comments. However, for Dry process Kiln, corelationship studied is quite good. Details are available in the proceedings of 8th NCB Seminar on Cement and Building Materials: - Paper published on “Clinker Quality Control- A case study” Authors: R. K. Saxena, B. A. Agate and Durgaprasad.)
However, in my opinion the strong and weak coefficient of co relationship relativeness may be used together with other spelled out norms for the selection of the clinker size fraction for litre weight determination as a scientific, logical and practical approach in the absence of expensive microscopic examination of clinker. Is it not!
Well Ted, can we say that the investigation methodology that is developed and presented in the ICR magazine is unique!
Looking forward to your endorsement.
It would be nice if you could send soft copies of your study reports on Litrewt vs.free lime on my E-mail ID bhaskar.agate@gmail.com
Regards
Bhaskar Agate