Iron oxides and hydroxides

28.21 - Iron oxides and hydroxides; earth colours containing 70 % or more by weight of combined iron evaluated as Fe203. 282 1.10 282 1.20 - Iron oxides and hydroxides - Earth colours Earth colours with a basis of natural iron oxides, containing 70 % or more by wei ht of combined iron calculated as Fe203, fall in this heading. For the p oses of assessmg w ether the 70 % limit has been reached, account must be taken of the tota iron content expressed as ferric oxide; thus a natural ferrous earth colour containing 84 % of ferric oxide (representing 58.8 % of pure iron) remains classified in the heading. E "P The heading also includes the following artificial oxides and hydroxides : (A) IRON OXIDES Ferric oxide (Fe203).Obtained from dehydrated ferrous sul hate or natural iron oxide. Fine1 divided owder, usually red but sometimes violet, yellowisI!' or black (violet, yellow or blacrc Bsed as a pigment (iron minim, .ewellers3rou e or colcothar , either m the ure state :g$kich case it is classified in this hea 'ng), or mixe with clay, ca cium sulphate benetian red), etc. (it then falls in Cha ter 32). It is used for rnakin ordinary or anti-rust paints, compounds for burnishing meta or polrshing lass, and vitrifia le compounds used to render the mass fusible in the manufacture of bottle-g ass. It also serves for preparing themite (mixed with aluminium powder), and for purifjmg coal gas, etc. f ? f d, f % (B) IRON HYDROXIDES (1) Ferrous hydroxide (Fe(OH)2). Obtained by the action of an alkali base on a ferrous salt. White solid which discolours in the presence of oxygen, turning into ferric hydroxide. (2) Ferric h droxide (brown oxide) (Fe(OH)3). Prepared by the action of an alkali base on a ferric s d A rust-coloured, reddish brown or vlolet-glintin product used as a pigment, either alone - in which case it is classified here - or mixed wi carbon, Prussian brown, etc. (saffion or Mars yellow), when it falls in headin 32.06. Ferric hydroxide is used in the manufacture of complex colours (Van brown, Van Dyck red,"English brown "," Swedish brown "). It is used 113 the pure state as an antidote to arsenic poisoning. f It is an amphoteric hydroxide which, after oxygenation, gives the ferrates of heading 28.41. This heading excludes : (a) Ferrous earth colours containing less than 70 % by weight of combined iron calculated as Fe203,or mixed together with other earth colours; micaceous iron oxide (heading 25.30). (b) Iron ores of heading 26.01, e-g., red haematite (including the oxides specular iron ore and rnartite), brown haematite (nainettes, the hydrated oxide containing iron and calcium carbonates), limonite (hydrated oxide), magnetite (magnetic oxide). (c) Iron scalin. s, crude oxides which become detached from the surface of iron brought to red heat or hammered beading 26.19). (d) Alkaline iron oxide for the purification of gas (heading 38.25). (e) Iron oxide (haematite) in the form of semi-preciousstones (heading 71.03 or 71.05). -