| 摘要 |
1,245,169. Iron oxide. PFIZER Inc. 27 Feb., 1969 [13 Nov., 1968], No. 10681/69. Heading C1A. High purity ferric oxide is prepared by cultivating an iron oxide bacterium under aerobic conditions in the presence of elemental iron, ferrous iron, and "ferrous sulphate" equivalent to at least one grain per litre of ferrous iron, at a pH from 2À2-3 and a temperature of 15-40‹ C., thereby precipitating hydrous ferric oxide. The "ferrous sulphate" is defined as anhydrous ferrous sulphate copperas, technical FeSO 4 .7H 2 O, or the complexes such as FeSO 4 .(NH 4 ) 2 SO 4 .6H 2 O and FeSO 4 .K 2 SO 4 . To the reaction may be added ferric hydroxide, yellow ferric hydroxide or red ferric oxide as seed for the hydrous ferric oxide. The preferred embodiment is Thiobacillus ferrooxidans as bacterium, copperas as "ferrous sulphate" with a ferrous iron concentration of 5-6 gms. per litre and a pH of 2À6-2À8. The process may be made continuous by the continuous or periodic addition of elemental iron and "ferrous sulphate" and the continuous or periodic removal of the hydrous ferric oxide containing liquor from which the hydrous ferric oxide is separated, to which additional nutrients are added and which is recycled to the reaction stage. The aqueous medium in which the bacterium is cultivated should also contain a source of nitrogen either in the form of ammonium ions or nitrate ions along with other inorganic salts. After separation the hydrous ferric oxide may be calcined at preferably above about 650‹ C. |
