| 摘要 |
Oxidisable pellets of crude iron core are hardened in a furnace using a horizontal or circular grid which carries a bed of pellets along a horizontal path through the furnace; and the pellets are heated by hot gases. The furnace has a zone (1) which is either the region of max. furnace temp. or is downstream of that region; in zone (1), the average pellet temp. is 593-1204 degrees C, and the current of gas travels downwards towards the bed. The periphery of at least part of zone (1) is covered by >=2 hoods to make a protected zone (1a, 1b) on each side above the grid which travels under the hoods; and >=1 current of oxygen is projected downwards under each hood onto the periphery of the grid so that the pellets are exposed to the O2 for >=5 seconds in zones (1a, 1b). The pellets are pref. at 704-1093 degrees C and exposed for min. 10 seconds in zones (1a, 1b), esp. using an excess of O2 above the theoretical amt. for converting the peripheral magnetite into haematite. Used for mfr. of iron ore pellets which are strong enough to withstand bulk storage, handling and transport without crumbling, before the pellets are used in a blast furnace for steel making. |
