... used as filler and improver. Purity: 98%min. Appearance: white powder. Heavy calcium carbonate, also called ground calcium carbonate, is ... Carbonate is widely used as filler and improver in plastic, paint, paper-making, rubber, pharmacy, feed, daily chemical, ceramics, ... Carbonate is widely used as filler and improver in plastic, paint, paper-making, rubber, pharmacy, feed, daily chemical, ceramics, ...