Some aspects on porous properties of iron oxides containing foreign oxides reduced by hydrogen
- PDF / 571,518 Bytes
- 7 Pages / 603.28 x 783.28 pts Page_size
- 75 Downloads / 215 Views
diameters increased as the amount of pores increased, and that neither phenomenon was recognized in the wiistite containing AI2Oa. H. Schenck e t a l 7 have reported that the volume change and pore volume change of a pellet at various degrees of reduction showed that, at the range of lower reduction degrees where the wOstite phase did not appear, micropores and macropores were separately distributed in the pellet and, as the reduction temperature grew higher, the micropore size became greater. However, there have been only a few studies making the quantitative measurement of the porous properties during reduction and almost none on green hematite compacts such as porous iron ores. In this report, the changes in porous structure during reduction were compared between green hematite compacts and indurated hematite compacts and the influence of contained foreign oxides on their structure was investigated. EXPERIMENTAL Materials The iron ore used was from India: Dempo 8 (60 to 100 mesh). The pure hematite was of a commercial grade and powder (-325 mesh) of 99.9 pct purity as claimed by the supplier. The three kinds of powder which are shown in Table I were mixed in as foreign oxides. The samples were reduced in a hydrogen gas of 99.99 pct purity. Preparation of Samples Each of the foreign oxides (5 wt pct) was added to the pure hematite and mixed as homogeneously as possible to form mixtures. The mixtures specimens were compressed under the pressure of 1.5 kg/cm z into round green compacts (12.8q~ x 2.5 mm). Some of the green compacts thus made were preheated in an electric furnace for 6 h at 1100 ~ in air.
ISSN 0360-2141/81 / 1211-0691500.75/0 9 1981 AMERICAN SOCIETY FOR METALS AND THE METALLURGICAL SOCIETY OF AIME
VOLUME 12B, DECEMBER 1981--691
Table I. Characteristics of Foreign Oxide Powders in Hematite Compact
Composition (Pet) Sample Amorphous SiO2 3,-A1203 a-AI203
AIzO3 < 0.05 >97 99.9
SiO2 >99.8 < 0.1
HCI
Data Loading...
