Influence of reduction conditions on the expansion and microtexture of sintered hematite compacts during the transition to magnetite

Disintegration of Northern Cape iron ores under reducing conditions

“…1 The reduction atmosphere significantly affects breakdown, with much less disintegration in atmospheres which contain hydrogen and water vapour, compared with CO/CO 2 atmospheres. 7 This difference was related to the higher nucleation rate of magnetite in the hydrogen containing atmosphere, and 'inward dilation', where the expansion is accommodated by expansion into pre-existing pores. 7 The specific focus of the present work is on the reduction disintegration of ore from the banded iron formation of the Northern Cape region in South Africa.…”

“…7 This difference was related to the higher nucleation rate of magnetite in the hydrogen containing atmosphere, and 'inward dilation', where the expansion is accommodated by expansion into pre-existing pores. 7 The specific focus of the present work is on the reduction disintegration of ore from the banded iron formation of the Northern Cape region in South Africa. This ore is a significant export from South Africa (amounting to 27?4 Mt in 2006); 8 it is categorised as a 'Type 2/4' ore in the Goldring 9 scheme (that is, ore hosted in a banded iron formation, with some supergene enrichment).…”

Tribochemical Activation of Iron Oxide for the Reduction of NO with CO: How Lattice Defects Can Influence the Catalytic Activity

“…When the reaction with CO is not limited to the surface active sites then the catalysts is rapidly following the chemistry of the blast‐furnace reduction of iron oxide. This reaction pathway requires the diffusion of iron out of the bulk material and onto the surface 10. Thus it is necessary to maximize the number on active sites but at the same time the bulk diffusion of the iron atoms has to be controlled.…”

Tribochemische Aktivierung von Eisenoxid für die Reduktion von NO mit CO: Wie Gitterbaufehler die katalytische Aktivität beeinflussen können

“…[8] Über einen intermediären Schritt zu N 2 O wird schlieûlich N 2 gebildet. [10] Somit ist es erforderlich, einerseits die Zahl der aktiven Zentren zu maximieren, aber auch die Volumendiffusion von Eisen zu kontrollieren.Die tribochemische (d. h. durch Zerreiben hervorgerufene) Aktivierung von käuflichem Hämatit führte zu einer deutlichen Verbesserung der Materialeigenschaften als Katalysator. Eisenoxid weist gegenüber vielen anderen Katalysatoren eine hohe Selektivität zugunsten von N 2 , aber nicht von N 2 O auf, [6,9] was für die Anwendung als Umweltschutzkatalysator von groûer Bedeutung ist.…”

“…[10] Somit ist es erforderlich, einerseits die Zahl der aktiven Zentren zu maximieren, aber auch die Volumendiffusion von Eisen zu kontrollieren. Dieser Reaktionszweig erfordert eine Diffusion von Eisen aus dem Volumen an die Oberfläche.…”