... commercially generated as a by-product during the manufacture of Titanium Dioxide, or as a by-product of the pickling of steel ... ferric oxide.Technical Index:ItemNational IndexEnterprise index (FeSO4 · H2O), % , ≥ 98 99 Fe,%, ≥ 19.7 20 Insoluble matter,%,≤ 0.5 0 ... ferric oxide.Technical Index:ItemNational IndexEnterprise index (FeSO4 · H2O), % , ≥ 98 99 Fe,%, ≥ 19.7 20 Insoluble matter,%,≤ 0.5 0 ...