55 posts
TimePosted 26/05/2011 14:48:06
armankhan says

sand stone...

friends what is the role of sand stone in cement process?  in which kiln conditions we can  add, reduce or  increase sand stone to rawmeal?

trainee engnr......


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Bhaskar Agate
81 posts
TimePosted 27/05/2011 04:32:52

Re: sand stone...

Raw meal is a Chemical composition of major oxides Silica(SiO2),Alumina(Al2O3), Irion(Fe2O3),Lime(CaO) and other minor oxides which are burnt at 1400-1500 deg.centigrade inside the furnace (Kiln) to produce intermediate product clinker.Gypsum is then added to manufacture cement.

Silica contribution comes predominantly from Sandstone.Similarly, Alumina from Bauxite,Iron from Hametite and Lime from Limestone minerals. These are the raw materials that we get from mother earth to manufacture cement.




Ted Krapkat
536 posts
TimePosted 27/05/2011 06:13:44

Re: sand stone...

Hello Armankhan,

Like sand, the role of sandstone is usually as a silica corrective. If used in the raw mix,  sandstone is likely to be a source of coarse quartz (>45um) which, if present in large enough quantities and large enough particle size, may detrimentally affect the kiln feed burnability. So, it is important to ensure that you grind the sandstone component fine enough.

Ideally, it is preferable to use a silica corrective that does not contain quartz (such as diatomite) or contains quartz as very fine particles (such as high-silica clay).

If sand or sandstone is the only silica corrective available and coarse quartz becomes an issue, then it may be necessary to grind the sandstone separately. This is because of the large difference in grindability between limestone and sandstone. When milled together, the limestone is ground very fine while the sandstone remains predominately in the coarse fraction.

Another issue with sandstone could be a high alkali content. You would have to consider the contribution of alkalis from this source to see if an increase in alkalis might be a problem for you.

Also, the use of large quantities of sandstone would probably increase the wear rates of mill internals.

Hope this helps...





20 posts
TimePosted 27/05/2011 06:47:16
avisgop says

Re: sand stone...

Dear Armaan the form of silica present in the rawmeal plays am important role in the burnability of the material as rightly pointed out by Mr Ted and the silica normally is available either as amorphous or crystalline form. the amorphous form does not affect the burnability as it is better in reactivity but the crystalline form ie the quartz form is detrimental for the burnability and therefore less reactive. It is always better to have these type of additives ground finer for making the mix reactive. it is always better to have a silica contribution from limestone if there is an availability of siliceous limestone with good calcium carbonate content. You can try to use Kaolin( if available or anyother corrective) which has good amount of silica and alumina content With less impurities which could reduce you the consumption of Sandstone. regards Arvind