This invention relates to magnetite-based sintered iron ore wherein a magnetite ore powder, which is not currently utilized owing to its low reducibility index among iron ore materials serving as a main material in iron-making processes, is improved so as to have a high reducibility index, and to a method of manufacturing the same.

A screening apparatus comprises superposed screening decks with an upper one of the screening decks having a pellet input, and each screening deck ends with an oversize pellet output, the screening decks have screens to screen the green ore pellets from top to bottom, the oversize pellet outputs feeding the travelling grate through pellet chutes with the oversize green ore pellets of one of the upper and the lower one of the screening decks being superposed to oversize green ore pellets of the other one of the lower and the upper one of the screening decks, the pellet chutes defining a curved delivery path with an input slope at the chute pellet input greater than an output slope of the chute pellet output to reduce a delivery speed of the green ore pellets from the oversize pellet output to the travelling grate. There is also provided a method for screening and delivering green ore pellets onto a travelling grate of an induration furnace.

A screening apparatus comprises superposed screening decks with an upper one of the screening decks having a pellet input, and each screening deck ends with an oversize pellet output, the screening decks have screens to screen the green ore pellets from top to bottom, the oversize pellet outputs feeding the travelling grate through pellet chutes with the oversize green ore pellets of one of the upper and the lower one of the screening decks being superposed to oversize green ore pellets of the other one of the lower and the upper one of the screening decks, the pellet chutes defining a curved delivery path with an input slope at the chute pellet input greater than an output slope of the chute pellet output to reduce a delivery speed of the green ore pellets from the oversize pellet output to the travelling grate. There is also provided a method for screening and delivering green ore pellets onto a travelling grate of an induration furnace.

The invention concerns a method of operating a sinter plant, where a sinter mix is fired in a sintering machine, the method including crushing fired sinter to below an upper particle size limit; screening the crushed sinter to remove fines and separate at least two sinter size fractions, typically smaller, intermediate and upper size fractions; storing each of the at least two sinter size fractions in a respective, separate storage bin, where
the screened sinter fractions are not mixed again at the sinter plant but are forwarded to the blast furnace plant, where they are stored in respective, separate storage bins, and the screened sinter fractions can be intermediately stored in separate bins at the sinter plant, before being forwarded to the blast furnace.

The invention concerns a method of operating a sinter plant, where a sinter mix is fired in a sintering machine, the method including crushing fired sinter to below an upper particle size limit; screening the crushed sinter to remove fines and separate at least two sinter size fractions, typically smaller, intermediate and upper size fractions; storing each of the at least two sinter size fractions in a respective, separate storage bin, where
the screened sinter fractions are not mixed again at the sinter plant but are forwarded to the blast furnace plant, where they are stored in respective, separate storage bins, and the screened sinter fractions can be intermediately stored in separate bins at the sinter plant, before being forwarded to the blast furnace.

A method produces a high-strength sintered ore while maintaining a high production rate by performing appropriate oxygen enrichment at a position closer to an ore discharging section than an ignition position without using gaseous fuel in the operation of a sintering machine. In a method for producing sintered ore including sequentially combusting carbonaceous material in a sinter bed (raw material charged layer) in a DL sintering machine to sinter the mixed raw material, in performing oxygen enrichment from above the raw material charging layer on the sintering machine, the oxygen enrichment is performed at a position closer to the ore discharging section than the position where 4 minutes have passed since the upper surface of the charging layer was ignited

A method of processing iron ore fines from various possible sources, with particle size up to 0.15 mm (through 100 mesh sieve) with no or limited comminution, directly into the intense mixer, with a set of binders in specific proportions, aiming to optimize physical and metallurgical properties of the pellets with minimal binder addition, thus not compromising the quality of steel products. The binders are starch, sodium silicate and sodium hydroxide, among others. The mixture with adjusted moisture content goes through conventional balling discs or drums and size screening. The green pellets then undergo drying with forced air at around 150° C. for a short time. The pellets obtained have excellent metallurgical properties, and compression resistance around 70 kgf/pellets, without the high and undesirable economic and environmental costs of the conventional indurating process. An alternative embodiment (FIG. 3) considers indurating the pellets at temperatures below 1,200° C. to obtain similar mechanical resistance than pellets made by the conventional induration process, with temperatures above 1,300° C.

An apparatus for the thermal treatment of lump or agglomerated material in a firing machine includes a travelling grate configured to convey the material through the firing machine. A firing chamber has a ceiling and side walls and is configured to generate temperatures required for the thermal treatment. The ceiling has a plurality of openings and the side walls have a plurality of burners that are directed obliquely upwards. A cooling zone is configured to pass cooling gases through the thermally treated material so as to heat the cooling gases. A recuperation tube is configured to recirculate the heated cooling gases to the firing chamber through the openings in the ceiling.

An apparatus for the thermal treatment of lump or agglomerated material in a firing machine includes a travelling grate configured to convey the material through the firing machine. A firing chamber has a ceiling and side walls and is configured to generate temperatures required for the thermal treatment. The ceiling has a plurality of openings and the side walls have a plurality of burners that are directed obliquely upwards. A cooling zone is configured to pass cooling gases through the thermally treated material so as to heat the cooling gases. A recuperation tube is configured to recirculate the heated cooling gases to the firing chamber through the openings in the ceiling.

Apparatus for supplying diluted gaseous fuel to not more than a lower limit combustion concentration at downstream of suction type sintering machine including a hood having similar width as a circularly-moving pallet and arranged above charged layer to surround the pallet in all directions, pipes disposed at upper position of charged layer in the hood and supplying the fuel air inside the hood, baffle plates formed by arranging plate materials having dog-leg shaped cross-section in plural rows and steps at intervals in the widthwise and height directions, respectively, of the hood to make each interval formed between adjacent plate materials in widthwise direction of the hood in each steps vertically alternate; fences having a void and arranged on both sides upper ends of the hood; vortex suppressing plates formed between fences at intervals having a void ratio, 20˜80%; whereby the gaseous fuel leakage supplied to the outside is prevented.