CPV code 24313300 designates Carbonates in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
24313300 sits under 24313000 (Sulphides, sulphates; nitrates, phosphates and carbonates) and groups 2 more specific sub-codes. When classifying a tender, choose the narrowest code that still covers the full subject of the contract.