Dear Sir,

We have receintly commisioned a new limestone cement milling plant on site.

The problem we are encountering during the performance tests is that the blain tends to start increacing after 24hrs on the same samples. We mill to 4500, this increases to 4600 to 4800 on the same sample after a few days. All the precations have been taken to ensure the blain apparaitus and the people are properly trained and the results are confirmed as being correct.

Are you able to assist us in explaining this fenomina.

Thank you.

I suspect this may be a problem of the method used to assess the surface area (Blaine) of the limestone. As the ground limestone ages the inter-particles forces diminish and then then limestone will pack more tightly into the Blaine apparatus cell. The resistance to air permeation rises and the apparent surface area is higher.

We see the same situation for all cement types produced. At the shipping station it is always 100-300 cm2/g higher than after the cyclones. So I do not think is a matter of limestone cement. Also we faced it than we took samples mannually. And I saw it at all plantes I worked for. Personnaly I am OK with it. May be it is a matter of some static tailings which to be lost after some time... Or temperature reduced...

I do belive that the issue is with large unstability of limestone you have used for the mill. Therefore Blaine increases from initial set level. Also I recommend to check sampling procedure you used to check that.