Hindustan Zinc s revenue from operations during the quarter ended September declined 16% year-on-year to Rs 6,619 crore as against Rs 8,127 crore in the same quarter of the previous year. The company has reported an EBITDA (earnings before interest, tax, depreciation and amortisation) of Rs 3,139 crore, down about 24% year-on-year. Margins too declined to 46.2%.