| 摘要 |
1,196,494. Production of iron oxides and oxysulphates. SOC DES ACCUMULATEURS FIXES ET DE TRACTION. 20 Dec., 1967 [21 Dec., 1966]. No. 57849/67. Heading C1A. Ferric oxide free from manganese is prepared by heating a ferrous sulphate solution in an acid medium, and in the presence of an oxidizing agent and sodium or potassium ions, to a temperature such that a sodium or potassium iron oxysulphate is precipitated. This precipitate is washed and dried, and heated in an oxidizing atmosphere to obtain ferric oxide e.g. at 875-925‹ C. The oxidizing agent may be air, ozone or hydrogen peroxide, but preferably sodium or potassium chlorate is used, in which case the additions of further sodium or potassium ions (as hydroxide or carbonate) is not necessary. The following double oxysulphates may be precipitated: 4Fe 2 O 3 .6SO 3 .Na 2 O.7H 2 O (struetural formula given) and 3Fe 2 O 3 .5SO 3 .K 2 O. 5H 2 O. Reduction of the ferric oxide at 500-550‹ C. results in pure magnetite. |
