1156 posts
Cement chemistry Question 15
What in your opinion would be the effect, on clinker properties (reactivity, granulometry, hardness...) of having a high LSF (97-98) and silica module (SM) of 2.8 and a low alumina module (AM) around 1.3-1.4? Would the high LSF tend to rise the C3S content, improving early strengths? High MS would shift the relationship C3S/C2S towards more C3S? also improving later strengths...if so, doing the opposite would rise the C2S and also the late strengths...but lowering the early ones? What about granulometry? We have seen that low AM, but lower LSF and SM gives a better granulometry and a darker clinker ... would you think that it will be the same under the conditions cited before (high LSF and high SM)? We produce a pozzolanic cement (20 per cent substitution) and would like to improve our late strengths. I believe it can only be done by working on the clinker, besides improving all the milling conditions, like Blaine and fineness, mill fill, gas flow, etc ... Please let me know your opinion.
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1156 posts
Re: Cement chemistry
High LSF will certainly increase the C3S content and the early strength of your cement. The high SM will increase the total silicates rather than specifically the C3S, and strengths at all ages. If you reduce the SM you can expect strengths to go down. The darker colour with low AM arises because of the increase in the C4AF content at the expense of the C3A and will apply at the high LSF and SM, although colour will lighten as the SM rises due to less total flux (C4AF and C3A). In terms of granulometry the effects are more difficult to predict and depends of your definition of good granulometry. Lower AM and therefore higher C4AF may increase the size of the clinker nodules due to earlier liquid formation in the kiln, however C3A can be a more effective flux than C4AF due to the higher relative volume compared to C4AF. I certainly agree that improving clinker quality and mineralogy is the key to strength enhancement and control in all types of blended cement, including pozzolanic cements. Please look for an article in the February issue of International Cement Review which talks about this topic as implemented at the Ladce factory of Cementaren Povazska in Slovakia.
1156 posts
Cement chemistry Question 16
We are producing sulphate resistant cement clinker. We believe from the analysis of the clinker that we could also produce oilwell cement as per API standard. Do you have any comments (analysis attached).
Secondly, our ALM has been reduced from 1.25 to 0.70 while keeping LSF as 0.90 and SIM 2.25 we are facing following problems:
1.Ring in inlet causing inlet spillage
2.Thick coating at 27-28m hampering production
How can we overcome these problems?
1156 posts
Re: Cement chemistry
Some classes of oil well cement have low C3A content and are coarsely ground. The key to producing oil well cements is the testing that is required to achieve the certification. You need to investigate the costs of installing the equipment to conduct this testing on a regular basis and then apply for certification to produce oil well cements. The ring and coating problems are caused by the high Fe2O3 content of the SR raw mix. I suggest you increase the silica modulus of the raw mix.