Raw material input for sale against ct-3

Dear Experts,

We are the manufacturers of non-ferrous castings. Only one customer of ours is 100% EOU, and he is issuing CT-3 for not charging any excise duty. One of our consultant is saying you can not take Input on Raw Material purchases for sale against CT-3, because you are not charging output. We have lot of raw materials like copper, zinc, aluminum, tin, lead etc to create a non-ferrous castings and in one melt we will be having the material of 100% EOU unit's and other customer’s. If the consultant is correct on his part how to bifurcate the raw material input. If any notification is there, kindly let me know.

Kindly clarify the same.

Thanks in Advance

Regards

ANTONY RAJ