WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
25.18 Dolomite, whether or not calcined or sintered, including dolomite roughly trimmed or merely cut, by sawin or otherwise, into blocks or slabs of a rectanguIar (including square) shape; dglomite ramming mix, 2518.10 - Dolomite not calcined or sintered - Calcined or sintered dolomite 25 18.30 - Dolomite ramming mix 25 18.20 Dolomite is a natural double carbonate of calcium and magnesium. The heading covers crude dolomite as well as calcined and sintered dolomite. Dolomite is calcined at a temperature range of 700 OC - 1000 'C to convert it into magnesium and caIciurn oxides by releasing carbon dioxide. On the other hand, sintered dolomite is obtained by heating dolomite to a temperature range of 1700 OC - 1900 OC when it becomes a refractory material. The heading also ~ncludesdolomite which has been roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (includmg square) shape. This heading further includes dolomite ramming mixes which are used as refractory materials (e.g., for furnace linin ). These products are traded in powder or granular form consisting on the field of application or predominantly of crus ed sintered dolomite. tem erature at which the mix will be used, different non- ydraulic binding agents (e.g., tar, pitc ,resins) are used. t DepenhnE However, the heading does not cover crushed dolomite for concrete aggregates, road metalling or railway ballast (heading 25.17).
Notes. 1.- Except where their context or Note 4 to this Chapter otherwise requires, the headings of this Chapter cover only products which are in the crude state or which have been washed (even with chemical substances eliminating the impurities without changing the structure of the product), crushed, ground, powdered, levigated, sifted, screened, concentrated by flotation, magnetic separation or other mechanical or physical processes (except crystallisation), but not products which have been roasted, calcined, obtained by mixing or subjected to processing beyond that mentioned in each heading. The products of this Chapter may contain an added anti-dusting agent, provided that such addition does not render the product particularly suitable for specific use rather than for general use. 2.- This Chapter does not cover : (a) Sublimed sulphur, precipitated sulphur or colloidal sulphur (heading 28.02); (b) Earth colours containing 70 % or more by weight of combined iron evaluated as Fe O 2 3 (heading 28.21); (c) Medicaments or other products of Chapter 30; (d) Perfumery, cosmetic or toilet preparations (Chapter 33); (e) Dolomite ramming mix (heading 38.16); (f) Setts, curbstones or flagstones (heading 68.01); mosaic cubes or the like (heading 68.02); roofing, facing or damp course slates (heading 68.03); (g) Precious or semi-precious stones (heading 71.02 or 71.03); (h) Cultured crystals (other than optical elements) weighing not less than 2.5 g each, of sodium chloride or of magnesium oxide, of heading 38.24; optical elements of sodium chloride or of magnesium oxide (heading 90.01); (ij) Billiard chalks (heading 95.04); or (k) Writing or drawing chalks or tailors' chalks (heading 96.09). 3.- Any products classifiable in heading 25.17 and any other heading of the Chapter are to be classified in heading 25.17. 4.- Heading 25.30 applies, inter alia, to : vermiculite, perlite and chlorites, unexpanded; earth colours, whether or not calcined or mixed together; natural micaceous iron oxides; meerschaum (whether or not in polished pieces); amber; agglomerated meerschaum and agglomerated amber, in plates, rods, sticks or similar forms, not worked after moulding; jet; strontianite (whether or not calcined), other than strontium oxide; broken pieces of pottery, brick or concrete.