Abstract
The thermal phase transformation of the iron-manganese phase of the PacificOcean manganese nodules were studied by the differential thermal and X-ray diffractionmethods. X-ray powder patterns of the heated samples at the temperature of 600°C to 1000°C show the occurrence of hematite, bixbyite and cubic and tetragonal (Fe, Mn) 3O4. Bixbyiteproduced by the heat treatment of the iron-manganese phase gives an abnormal X-ray patternin comparison with the standard sample of bixbyite. Cubic (Fe, Mn) 3O4 is produced notonly by the reaction of bixbyite with hematite over 900°C, but also at the lower temperature, such as 600°C. While, tetragonal (Fe, Mn) 3O4 is a reaction product of cubic (Fe, Mn) 3O4with bixbyite over 900°C in the case of manganese rich nodules. The species and quantitiesof the products after the heat treatment are assumed to be mostly influenced by the relativecontents of iron and manganese in the manganese nodule.
