Special additional duty customs can avail

hi

      we are a manufacture we paid some special addtional duty on customs for import of raw material as well as capital goods . i want to know whether they duty paid by us can claim as cenvat credit ,for capital goods if any 50% in current year & 50% in subsquent year applicable and also we are not going to export ,so the credit i taken can adjust against payment of excise duty .please clarify as earliest.

Thanks in Advance