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2011-Sustainable Industrial Processing Summit
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| Editors: | Florian K |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2012 |
| Pages: | 828 pages |
| ISBN: | 978-0-9879917-0-6 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Dissolution Of Chromite In Slags
Rauf Hurman Eric1; Orhan Demir1;1UNIVERSITY OF THE WITWATERSRAND, Johannesburg, South Africa;
Type of Paper: Invite
Id Paper: 374
Topic: 4
Abstract:
The dissolution of chromite from Bushveld Complex of South Africa in liquid slags was studied experimentally. The slag compositions chosen were representative of the ferrochromium production and stainless steel making. The dissolution process was monitored by chemical analysis of the samples taken from the melt at predetermined time intervals and SEM-EDAX analysis of reacted chromite cylinders. Experimental procedure involved the use of rotating cylinder technique in an inductively heated quartz reaction tube under the flow of argon gas in the temperature range 1550 to 1665 degrees centigrade. Empirical relations between the slag composition and the dissolution of chromite and the effect of different degrees of reducing conditions were established by using a statistical model. With this, a large amount of information in regard to the effect of slag composition on the dissolution of chromite was made available over a large range of slag compositions for practical applications.The empirical relations have shown that the chromite dissolution in silica-alumina-calcium oxide-magnesium oxide slag system increased with increasing alumina, increasing basicity, decreasing silica and decreasing oxygen partial pressure in the system. The dissolution of chromite also increased with increasing rotational speeds indicating the possibility of diffusion control of the process. SEM-EDAX studies on the reacted chromite cylinders showed that coring took place within the chromite grains subjected to dissolution reactions for a sufficient length of time. Chromium and iron concentrations in the chromite phase were decreasing when moving from the centre toward the surface of the grains where else aluminium and magnesium concentrations were increasing in the same direction indicating the opposite diffusion of these species. The slag also penetrated into the chromite grains increasing the silica content of the grains together with alumina and magnesium oxide.