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 for operating a blast furnace with which, even in the case where there is an increase in the powder ratio of coke to be charged into the blast furnace, it is possible to achieve the stabilization of blast furnace operation. The method includes blowing air through a tuyere disposed in a lower part of the blast furnace, successively measuring a particle size distribution of coke transported to the blast furnace, and adjusting at least one of a blast volume and a coke ratio in accordance with an index derived from the particle size distribution.

The present invention relates to an ironmaking feedstock comprising a solid CaFe.sub.3O.sub.5 phase. The ironmaking feedstock may be produced by a process comprising reacting a combination of a calcium source and magnetite at elevated temperature under reducing conditions sufficient to produce the solid CaFe.sub.3O.sub.5 phase. The product may be in the form of agglomerates such as pellets, with a compressive strength such that the product is suitable for transportation.

A method for measuring the softening and melting performances of iron ore in blast furnace is disclosed, which is implemented by a device including a high temperature furnace, gas supply system, a loading system and a weighing system. The method includes: step 1: the dried coke and iron ore specimen are placed in the graphite crucible in a specified way; step 2: the graphite crucible is placed in the high temperature furnace, and N.sub.2 is continuously fed into the high temperature furnace to reach an airtightness requirement; step 3: a vacuum pump is used to extract mixed gas in a hearth of the high temperature furnace and heating process is started; step 4: both the composition of mixed gas and pressure imposed on the iron ore are controlled according to the designed temperature variation; step 5: data are acquired to calculate.

The use of pellets comprising one or more thermoplastic material(s) of more than 40%, based on the total dry weight of the pellets and one or more cellulosic material(s) of more than 20%, based on the total dry weight of the pellets, as a reducing agent in a process for making pig iron in a blast furnace. The pellets can be provided in unground form, as a partial replacement of coke through the top of the blast furnace, or can be provided as reducing agent in the raceway in an amount of higher than 10 kg/ton iron.

A liquid feed for a basic oxygen furnace, a method to obtain the liquid feed and a steel plant producing such a liquid feed, wherein the liquid feed includes a first liquid iron stream of carburised molten scrap and a second liquid iron stream from an iron making process, thereby allowing a maximum use of scrap intake while preparing high quality steel products.

A method for charging raw materials into a blast furnace is provided. The blast furnace includes a bell-less charging device that includes a plurality of main hoppers and an auxiliary hopper. The auxiliary hopper has a smaller capacity than the main hoppers. The method includes discharging ore charged in at least one of the plurality of main hoppers and then sequentially charging the ore from a furnace center side toward a furnace wall side by using a rotating chute. After charging of the ore is started, only the ore is charged from the rotating chute at least until charging of 15 mass % of the ore is completed based on a total amount of the ore to be charged per batch; then discharging of small-size coke charged in the auxiliary hopper is started; and then, the small-size coke is charged together with the ore from the rotating chute.

The present invention relates to a process and to a system for eliminating the expandability of steel-plant slag, which comprises a primary crusher (3) to reduce the fragments according to their granulometry; a magnetic separator (4) to remove metallic fragments bigger than a determined granulometry (5); a rotary dryer (6) to dry slag free from bigger metallic fragments; an impact mill (11) to disaggregate and fragment slag particles that are bigger than a predetermined granulometry; a classifier (12) for aero-classification and drag of fine and superfine particles; a cooler (17) for cooling slag particles bigger than a predetermined granulometry by means of heat exchange and removal of the fine and superfine particles that were not collected by the impact mill (11); a vibrating sieve (21) provided with two or more decks (23, 24, and 25) with screens of predetermined sizes; low-intensity magnetic separators (26, 27 and 28), with generation of non-magnetic slag fractions free from metallic iron and from iron monoxide, and of magnetic fractions composed by metallic iron and iron monoxide; and low-intensity magnetic separators (35, 36 and 37) to reprocess the magnetic fractions with generation of concentrate with high metallic iron contents and a product with high concentration of iron monoxide.

A method for detecting an air flow distribution in a blast furnace, taking into account a heat exchange between an air flow and a solid material bed and the effect of a distribution of a material layer structure in a radial direction of a blast furnace on the radial air permeability of blast furnace, which affects a mode of air flow distribution, wherein the distribution of the air flow and the radial material layer structure of the blast furnace can be calculated by combining a cross-shaped temperature-measuring gun and other main blast furnace operating parameters. According to the detection method, a blast furnace operator can timely and accurately infer, from a change in a current radial air flow temperature distribution, the direction of change of the distribution of the air flow and the radial material layer structure at a furnace throat portion.

Provided is a blast-furnace operating method including: a first step of adjusting a charging rate of coke while monitoring a furnace-top temperature T.sub.top; a second step of adjusting an injection rate of pulverized coal while monitoring an in-furnace superficial gas velocity u and the furnace-top temperature T.sub.top; a third step of adjusting an oxygen-enrichment ratio of oxygen-enriched air while monitoring a tuyere combustion temperature T.sub.f and the furnace-top temperature T.sub.top; and a fourth step of determining whether an injection rate of the oxygen-enriched air needs to be adjusted, based on a value of the in-furnace superficial gas velocity u.