This heading covers only apatite and other natural calcium phosphates (tricalcium phosphates or phosphorites), natural aluminium calcium phosphates and phosphatic chalks (chalk naturally mixed with calcium phosphate).
These products remain in this heading even when ground for use as fertilisers or if they have been heat treated merely to remove impurities. But the heading does not include the products when they are calcined or further heat treated than for the removal of impurities (heading 31.03 or 31.05).
clhs@clhs.co.kr 
070-4214-8300