On the basis of data obtained by means of analyzing coal, a first and second coal type satisfying conditions are selected, the ash melting point of the mixed coal resulting from mixing the first and second coal types is derived on the basis of a four-dimensional state diagram for SiO.sub.2CaOMgO-20% Al.sub.2O.sub.3, on the basis of the ash melting point of the mixed coal and the four-dimensional state diagram, an additive causing the ash melting point of the mixed coal to be at least 1400 C. at the lowest quantity when added to the mixed coal is selected from SiO.sub.2, MgO, and CaO, the addition quantity of the additive is derived, the first coal type and second coal type are mixed to result in the mixed coal, and the addition quantity of the additive is added to the mixed coal.

Provided is a method for preparing blast furnace blow-in coal that can, at a low cost, obtain blast furnace blow-in coal that suppresses occlusion by blast furnace blow-in ash or accretion of blast furnace blow-in ash in a pathway leading to a tuyere of a blast furnace main body, while suppressing a decrease in the amount of heat release. The method includes selecting first and second coal types satisfying conditions (S2, S3), on the basis of the CaO content in the ash when the oxides of Al, Si, Ca, and Mg in the ash is 100 wt % and the Al.sub.2O.sub.3 content in the ash is 20 wt %, deriving the mixing ratio of the first and second coal types that results in the CaO content in the ash of the mixed coal being at least 40 wt % (S4), and mixing the first and second coal types (S5) at the mixing ratio.

A method for preparing coal which is to be injected into a blast furnace includes: a step (S1) for analyzing the ash of coal in a raw-coal stage and determining the contents (wt %) of At Si, Ca and Mg in the ash; a step (S2) for deriving the ash melting point of the coal on the basis of the obtained data: a step (S3) for selecting a metal species to be supported on the coal and deriving the amount thereof to be supported on the basis of the obtained data so as to adjust the melting point of the ash of the coal to 1200 to 1400 C.; a step (S4) for making the metal supported on the coal in the derived amount by an ion-exchange method; and a step (S5) for carbonizing the coal obtained in the step (4).

A Powder feeding system for feeding powder in a feed tank via a valve for powder downstream of the feed tank and through a powder delivery pipe, the Powder feeding system including: a powder fluidizing portion provided in the feed tank and configured to introduce fluidizing gas for fluidizing the powder; and a powder refluidizing portion provided between the powder fluidizing portion and the valve for powder and configured to introduce refluidizing gas for refluidizing the powder.

A blast furnace includes: a blast furnace body; raw material charging means for charging raw material into the blast furnace body; hot air blowing means for blowing hot air into the blast furnace body; a drying apparatus etc. for evaporating moisture in low-grade coal; a dry distillation apparatus etc. for carbonizing dried coal; a cooling apparatus etc. for cooling carbonized coal; a pulverization apparatus etc. for pulverizing the carbonized coal cooled by the cooling apparatus; a storage tank for storing powdered coal; a nitrogen gas supply source, a conveyor line and a cyclone separator etc. for conveying the powdered coal pulverized by the pulverization apparatus to the inside of the storage tank by generating a gas flow with the nitrogen gas; and an injection lance etc. for feeding the powdered coal inside the storage tank to hot air that is blown into the blast furnace body.

A process for processing metal ore includes: reducing a metal ore, particularly a metallic oxide, in a blast furnace shaft; producing furnace gas containing CO.sub.2, in the blast furnace shaft; discharging the furnace gas from the blast furnace shaft; directing at least a portion of the furnace gas directly or indirectly into a CO.sub.2-converter; and converting the CO.sub.2 contained in the furnace gas into an aerosol consisting of a carrier gas and C-particles in the CO.sub.2-converter in the presence of a stoichiometric surplus of C; directing at least a first portion of the aerosol from the CO.sub.2-converter into the blast furnace shaft; and introducing H.sub.2O into the blast furnace shaft. By virtue of the reaction C+H.sub.2O.fwdarw.CO.sub.2+2H, nascent hydrogen is produced in the blast furnace which causes rapid reduction of the metal ore. The speed of reduction of the metal ore is thus increased, and it is possible to increase either the throughput capacity of the blast furnace or to reduce the size of the blast furnace. An aerosol in the form of a fluid is easily introducible into the blast furnace shaft.

A method for a blast furnace includes pulverizing coal to make pulverized coal, and pulverizing iron ore to make pulverized iron ore, and injecting the pulverized coal and the pulverized iron ore from a tuyere. A loss on ignition of the iron ore is greater than or equal to 9% by mass and less than or equal to 12% by mass, an injection rate of the pulverized coal is greater than or equal to 150 kg/tp, and an injection rate of the pulverized iron ore is greater than or equal to 2.5 kg/tp and less than or equal to 50.0 kg/tp.

A method for producing pig iron using a blast furnace including a tuyere, the method including charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace and reducing and melting the iron ore material in the first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere. The iron ore material contains a reduced iron molded product obtained by compression molding of reduced iron, the auxiliary reductant contains pulverized coal, a blending amount of the reduced iron is greater than or equal to 200 kg per ton of pig iron to be produced, a reducing agent ratio of a reducing agent containing the coke and the pulverized coal is less than or equal to 440 kg/tp, and a pulverized coal ratio is greater than or equal to 130 kg/tp.

A production method of pig iron using a blast furnace with a tuyere includes: charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace; and reducing and melting the iron ore material in the charged first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere, in which: an aggregate for letting through the hot air to a central portion of the blast furnace is blended into the first layer; and the aggregate contains a reduced iron molded product obtained through compression molding of reduced iron.