CementUser:

Also we see a variation in sulphur content of the white cement from the range of 2.6 to 3.5. We find the issue of lumping more in those white cements where the sulphur content is higher.

 Since SO3 content is directly proportional to the amount of gypsum present in the white cement, this observation tends to confirm that the lumping is related to the gypsum. 

CementUser:

Also this issue is not found in products with same characteristics, but no hydrated lime from the same mill.

This, however, suggests another cause;- There may be residual water in the hydrated lime, which may also vary from batch to batch. Anhydrous CaCl2 will quickly take up this free moisture and possibly cause lumping, if there is sufficient moisture present.

Regards,

Ted.

Thank you for your reply.

Anhydrous calcium chloride which is used is a necessity as this product is actually a type of paint.A lower dosage will result in the product not setting at all. The dosage of Cacl2 in the product has not changed since when the issue did not exist.

The final product which is discharged has moisture content less than 0.8% at time of discharge. 

Ted,

Gypsum content of the cement manufacturer is not in my control. 

As indicated, we have alreay removed lime. However, the problem may reoccur if the cement manufacturer again increases the gypsum. In the same time/period the particle size of the cement too has varied a lot. If it is helpful, I can post a graph of the test data over the last 2 years of the cement manufacterer.

 I have done all I can do at my end, including QC to raw material change to anti caking agent incorporation.

So how do I take care of this issue at my end?

 Please advise.

CementUser:

Gypsum content of the cement manufacturer is not in my control.

 As indicated, we have alreay removed lime. However, the problem may reoccur if the cement manufacturer again increases the gypsum. In the same time/period the particle size of the cement too has varied a lot. If it is helpful, I can post a graph of the test data over the last 2 years of the cement manufacterer.

 I have done all I can do at my end, including QC to raw material change to anti caking agent incorporation.

So how do I take care of this issue at my end? 

I guess that all you are left with is to approach the cement supplier and voice your concerns with his product. Most cement companies have a technical sales team who can help customers with technical issues like this, especially if the problem is related to variability of their product.

 Good luck,

 Ted.