Method for improving fluidity of ironmaking raw materials and ironmaking method

Abstract

To provide a fluidity improving agent for ironmaking raw materials having excellent fluidity, a method for improving fluidity of ironmaking raw materials using the fluidity improving agent, and an ironmaking method using the fluidity improving agent.SOLUTION: A fluidity improving agent for ironmaking raw materials comprises an ester compound. The ester compound has a flash point of 250°C or higher. The kinematic viscosity of the ester compound at 40°C is 1.0×10-4 m2 / s or less. The solubility of the ester compound in water at 25°C is less than 1 g / 100 g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a flowability improver for raw materials for ironmaking, a method for improving the flowability of raw materials for ironmaking, and a method for ironmaking. [Background technology]

[0002] It has been known to produce iron and steel from iron-making raw materials (e.g., coal, iron ore, limestone, recovered dust from each iron-making process, etc.). Specifically, coal is carbonized to produce coke, and iron ore and limestone are sintered to produce sintered ore, and the coke and sintered ore are then used to produce iron and steel.

[0003] In the production of coke, a method for increasing the bulk density of coal for coke production has been proposed in which polyoxyethylene alkyl ether sulfate (bulk density improver) is added to coal (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-77368 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, when raw materials for ironmaking arrive at and are stored in a raw material storage area, moisture adheres to the raw materials, which reduces the fluidity of the raw materials and leads to a problem of reduced productivity. Furthermore, raw materials for ironmaking are transported using transport equipment (e.g., conveyors, chutes, liners, grates, and hoppers), but the raw materials stick to the transport equipment, which reduces transportability. Therefore, methods for improving the fluidity of raw materials for ironmaking are being considered.

[0006] The present invention provides a flowability improver for ironmaking raw materials having excellent fluidity, a method for improving the fluidity of ironmaking raw materials using the flowability improver for ironmaking raw materials, and a method for ironmaking using the flowability improver for ironmaking raw materials. [Means for solving the problem]

[0007] The present invention [1] is directed to an ester compound, the ester compound having a flash point of 250°C or higher, and a kinematic viscosity at 40°C of 1.0 x 10 -4 m 2 / s or less, and the solubility of the ester compound in water at 25°C is less than 1 g / 100 g.

[0008] The present invention [2] further includes the flowability improver for raw materials for iron making described in the above [1], which contains mineral oil.

[0009] The present invention [3] includes the fluidity improver for raw materials for iron-making according to the above [1] or [2], in which the ester compound is a monoester compound.

[0010] The present invention [4] includes a method for improving the fluidity of raw materials for iron-making, which comprises blending the flowability improver for raw materials for iron-making described in any one of the above [1] to [3] to raw materials for iron-making.

[0011] The present invention [5] includes a method of making iron comprising a first step of carbonizing a first ironmaking raw material containing coal to produce coke, a second step of sintering a second ironmaking raw material containing iron ore to produce sintered ore, and a third step of producing steel from the coke and the sintered ore, wherein the first ironmaking raw material in the first step and / or the second ironmaking raw material in the second step is blended with a flowability improver for ironmaking raw materials described in any one of [1] to [3] above. [Effects of the Invention]

[0012] The flowability improver for raw materials for iron making of the present invention contains an ester compound, and the ester compound has a flash point of 250°C or higher and a kinematic viscosity at 40°C of 1.0 x 10 -4 m 2 / s or less, and the solubility of the ester compound in water at 25°C is less than 1 g / 100 g. Therefore, the fluidity can be improved.

[0013] The method for improving the fluidity of raw materials for iron-making of the present invention involves blending the flowability improver for raw materials for iron-making of the present invention with the raw materials for iron-making, thereby improving the fluidity.

[0014] In the iron-making method of the present invention, the flowability improver for iron-making raw materials of the present invention is blended with the first iron-making raw material in the first step and / or the second iron-making raw material in the second step, thereby improving the flowability. DETAILED DESCRIPTION OF THE INVENTION

[0015] 1. Fluidity improver for steelmaking raw materials A flowability improver for iron-making raw materials (hereinafter sometimes referred to as a flowability improver) improves (enhances) the flowability of iron-making raw materials.

[0016] Iron and steel raw materials are the raw materials used to produce iron and steel.

[0017] The raw materials for iron making are preferably powdered or granular, and have an average particle size of, for example, 0.1 μm to 100 mm, or preferably 10 μm to 10 mm.

[0018] Examples of raw materials for iron making include coal, iron ore, limestone, quicklime, slag, and collected dust.

[0019] The raw materials for iron making may be a single material or a mixture of the above materials.

[0020] The flow improver includes an ester compound.

[0021] <Ester compounds> An ester compound has one or more ester groups in one molecule and does not have a hydroxyl group or a carboxyl group.

[0022] An ester compound is a reaction product of an acid (carboxylic acid) and an alcohol.

[0023] Preferably, at least one of the acid and the alcohol has 10 or more and 30 or less carbon atoms.

[0024] Examples of the ester compound include a monoester compound, a diester compound, a triester compound, and a tetraester compound.

[0025] [Monoester compounds] Examples of the monoester compound include a reaction product of a monocarboxylic acid and a monool.

[0026] Examples of the monocarboxylic acid include an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, and an aromatic monocarboxylic acid. Preferably, the monocarboxylic acid is an aliphatic monocarboxylic acid.

[0027] Examples of the aliphatic monocarboxylic acid include saturated aliphatic monocarboxylic acids and unsaturated aliphatic monocarboxylic acids.

[0028] Examples of saturated aliphatic monocarboxylic acids include linear saturated aliphatic monocarboxylic acids having 10 to 30 carbon atoms.

[0029] Examples of saturated aliphatic monocarboxylic acids having 10 to 30 carbon atoms include decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid), nonadecanoic acid, and icosanoic acid.

[0030] Examples of unsaturated aliphatic monocarboxylic acids include linear unsaturated aliphatic monocarboxylic acids having 10 to 30 carbon atoms.

[0031] Examples of the straight-chain unsaturated aliphatic monocarboxylic acid having 10 to 30 carbon atoms include myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, and eicosenoic acid. A preferred example of the straight-chain unsaturated aliphatic monocarboxylic acid having 10 to 30 carbon atoms is oleic acid.

[0032] As the aliphatic monocarboxylic acid, from the viewpoint of improving fluidity, preferably, an unsaturated aliphatic monocarboxylic acid is used.

[0033] The monocarboxylic acids can be used alone or in combination of two or more kinds.

[0034] Examples of the monool include an aliphatic monool, an alicyclic monool, and an aromatic monool. Preferably, the monool is an aliphatic monool.

[0035] The aliphatic monool includes a linear aliphatic monool and a branched aliphatic monool.

[0036] Examples of the straight-chain aliphatic monool include straight-chain aliphatic monools having 1 to 9 carbon atoms and straight-chain aliphatic monools having 10 to 30 carbon atoms.

[0037] Examples of the linear aliphatic monool having 1 to 9 carbon atoms include methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, and 1-nonanol.

[0038] Examples of linear aliphatic monools having 10 to 30 carbon atoms include 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 1-pentadecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, 1-nonadecanol, and 1-eicosanol.

[0039] Examples of the branched aliphatic monool include branched aliphatic monools having 1 to 9 carbon atoms and branched aliphatic monools having 10 to 30 carbon atoms.

[0040] An example of the branched aliphatic monool having 1 to 9 carbon atoms is 2-ethylhexanol.

[0041] Examples of the branched aliphatic monool having 10 to 30 carbon atoms include 2-propylheptanol, 2-butyloctanol, 1-methylheptadecanol, 2-hexyloctanol, 1-hexylheptanol, isooctanol, isodecanol, and isotridecanol.

[0042] The aliphatic monool is preferably a branched aliphatic monool, and more preferably a branched aliphatic monool having 10 to 30 carbon atoms.

[0043] The monools can be used alone or in combination of two or more.

[0044] The monoester compound is obtained by subjecting a monocarboxylic acid (1 mole) and a monool (1 mole) to an esterification reaction.

[0045] A preferred example of the monoester compound is a reaction product of oleic acid and isotridecanol (isotridecyl oleate).

[0046] [Diester compounds] Examples of diester compounds include reaction products of monocarboxylic acids and diols, and reaction products of dicarboxylic acids and monools.

[0047] Examples of the dicarboxylic acid include an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aromatic dicarboxylic acid. Preferably, the dicarboxylic acid is an aliphatic dicarboxylic acid.

[0048] Aliphatic dicarboxylic acids include, for example, saturated dicarboxylic acids and unsaturated dicarboxylic acids.

[0049] Examples of saturated dicarboxylic acids include saturated dicarboxylic acids having 1 to 9 carbon atoms and saturated dicarboxylic acids having 10 to 30 carbon atoms.

[0050] Examples of saturated dicarboxylic acids having 1 to 9 carbon atoms include ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), n-butanedioic acid (succinic acid), n-heptanedioic acid (glutaric acid), n-hexanedioic acid (adipic acid), n-heptanedioic acid, n-octanedioic acid, and n-nonanedioic acid (azelaic acid).

[0051] Examples of saturated dicarboxylic acids having 10 to 30 carbon atoms include n-decanedioic acid (sebacic acid), n-undecanedioic acid, n-dodecanedioic acid, n-tridecanedioic acid, n-tetradecanedioic acid, n-pentadecanedioic acid, and n-hexadecanedioic acid.

[0052] Examples of unsaturated dicarboxylic acids include unsaturated dicarboxylic acids having 1 to 9 carbon atoms. Examples of unsaturated dicarboxylic acids having 1 to 9 carbon atoms include maleic acid, fumaric acid, and itaconic acid.

[0053] The dicarboxylic acids can be used alone or in combination of two or more kinds.

[0054] The diol may be, for example, an aliphatic diol, an alicyclic diol, or an aromatic diol. Preferably, the diol is an aliphatic diol.

[0055] Examples of diols include diols having 1 to 9 carbon atoms. Examples of diols having 1 to 9 carbon atoms include ethylene glycol, propylene glycol, butylene glycol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol. A preferred example of a diol having 1 to 9 carbon atoms is neopentyl glycol.

[0056] The diols can be used alone or in combination of two or more.

[0057] The diester compound can be obtained by esterifying a monocarboxylic acid (2 moles) with a diol (1 mole) or by esterifying a dicarboxylic acid (1 mole) with a monool (2 moles).

[0058] A preferred example of the diester compound is a reaction product of oleic acid and neopentyl glycol (neopentyl glycol dioleate).

[0059] [Triester compounds] Examples of triester compounds include reaction products of tricarboxylic acids and monools, and reaction products of monocarboxylic acids and triols.

[0060] Examples of tricarboxylic acids include aliphatic tricarboxylic acids, alicyclic tricarboxylic acids, and aromatic tricarboxylic acids. Preferably, the tricarboxylic acid is an aliphatic tricarboxylic acid.

[0061] Examples of the aliphatic tricarboxylic acid include saturated aliphatic tricarboxylic acids and unsaturated aliphatic tricarboxylic acids.

[0062] Examples of saturated aliphatic tricarboxylic acids include saturated aliphatic tricarboxylic acids having 1 to 9 carbon atoms and saturated aliphatic tricarboxylic acids having 10 to 30 carbon atoms.

[0063] Examples of saturated aliphatic tricarboxylic acids having 1 to 9 carbon atoms include butanetricarboxylic acid and pentanetricarboxylic acid.

[0064] Examples of saturated aliphatic tricarboxylic acids having 10 to 30 carbon atoms include hexanetricarboxylic acid and octanetricarboxylic acid.

[0065] Examples of unsaturated aliphatic tricarboxylic acids include unsaturated aliphatic tricarboxylic acids having 1 to 9 carbon atoms. Examples of unsaturated aliphatic tricarboxylic acids having 1 to 9 carbon atoms include aconitic acid.

[0066] The tricarboxylic acids can be used alone or in combination of two or more.

[0067] Examples of the triol include an aliphatic triol, an alicyclic triol, and an aromatic triol. Preferably, the triol is an aliphatic triol.

[0068] Examples of the aliphatic triol include aliphatic triols having 1 to 9 carbon atoms. Examples of the aliphatic triols having 1 to 9 carbon atoms include trimethylolethane, trimethylolpropane, trimethylolbutane, glycerin, and 1,3,5-pentanetriol. A preferred example of the aliphatic triols having 1 to 9 carbon atoms is trimethylolpropane.

[0069] The triols can be used alone or in combination of two or more.

[0070] The triester compound can be obtained by esterifying a tricarboxylic acid (1 mole) with a monool (3 moles), or by esterifying a monocarboxylic acid (3 moles) with a triol (1 mole).

[0071] The triester compound is preferably a reaction product of a monocarboxylic acid and a triol, and more preferably a reaction product of oleic acid and trimethylolpropane (trimethylolpropane trioleate).

[0072] [Tetraester compounds] Examples of the tetraester compound include a reaction product of a tetracarboxylic acid and a monool, and a reaction product of a monocarboxylic acid and a tetraol.

[0073] Examples of the tetracarboxylic acid include aliphatic tetracarboxylic acids, alicyclic tetracarboxylic acids, and aromatic tetracarboxylic acids. Preferably, the tetracarboxylic acid is aliphatic tetracarboxylic acid.

[0074] Examples of the aliphatic tetracarboxylic acid include saturated aliphatic tetracarboxylic acids and unsaturated aliphatic tetracarboxylic acids.

[0075] Examples of saturated aliphatic tetracarboxylic acids include saturated aliphatic tetracarboxylic acids having 1 to 9 carbon atoms and saturated aliphatic tetracarboxylic acids having 10 to 30 carbon atoms.

[0076] An example of the saturated aliphatic tetracarboxylic acid having 1 to 9 carbon atoms is butanetetracarboxylic acid.

[0077] An example of the saturated aliphatic tetracarboxylic acid having 10 to 30 carbon atoms is octanetetracarboxylic acid.

[0078] Examples of saturated aliphatic tetracarboxylic acids include saturated aliphatic tetracarboxylic acids having 1 to 9 carbon atoms. Examples of saturated aliphatic tetracarboxylic acids having 1 to 9 carbon atoms include 4-pentene-1,2,3,4-tetracarboxylic acid.

[0079] The tetracarboxylic acids can be used alone or in combination of two or more kinds.

[0080] Examples of the tetraol include an aliphatic tetraol, an alicyclic tetraol, and an aromatic tetraol. Preferably, the tetraol is an aliphatic tetraol.

[0081] Examples of the aliphatic tetraols include aliphatic tetraols having 1 to 9 carbon atoms. Examples of the aliphatic tetraols having 1 to 9 carbon atoms include pentaerythritol and diglycerin. A preferred example of the aliphatic tetraols having 1 to 9 carbon atoms is pentaerythritol.

[0082] Tetraols can be used alone or in combination of two or more.

[0083] The tetraester compound can be obtained by esterifying a tetracarboxylic acid (1 mole) with a monool (4 moles), or by esterifying a monocarboxylic acid (4 moles) with a tetraol (1 mole).

[0084] The tetraester compound is preferably a reaction product of a monocarboxylic acid and a tetraol, and more preferably a reaction product of oleic acid and pentaerythritol (pentaerythritol tetraoleate).

[0085] As the ester compound, a monoester compound can be mentioned from the viewpoint of further improving the flowability.

[0086] The flash point of the ester compound is 250°C or higher, and for example, 350°C or lower, preferably 330°C or lower, and more preferably 310°C or lower.

[0087] When the flash point of the ester compound is equal to or higher than the lower limit, the availability can be improved.

[0088] The flash point can be measured using a Cleveland open cup flash point tester.

[0089] The kinematic viscosity of the ester compound at 40°C is 1.00 x 10 -4 m 2 / s or less, preferably 0.80 × 10 -4 m 2 / s or less, more preferably 0.60 × 10 -4 m 2 / s or less, more preferably 0.40 × 10 -4 m 2 / s or less, particularly preferably 0.20 × 10 -4 m 2 / s or less, most preferably 0.15 × 10 -4 m 2 / s or less, for example, 0.01 × 10 -4 m 2 / s or more.

[0090] When the kinematic viscosity of the ester compound at 40°C is equal to or less than the upper limit, the fluidity can be improved.

[0091] On the other hand, if the kinematic viscosity of the ester compound at 40°C exceeds the upper limit, the fluidity decreases.

[0092] The kinematic viscosity at 40°C can be measured in accordance with JIS K 2283.

[0093] The ester compound has a solubility in water at 25° C. of less than 1 g / 100 g, and for example, 0.01 g / 100 g or more.

[0094] That is, the ester compound is an oil that is substantially insoluble in water (in other words, an ester oil), and is distinguished from, for example, a surfactant.

[0095] When the solubility is equal to or less than the upper limit, the fluidity can be improved.

[0096] If the solubility exceeds the upper limit, the fluidity decreases.

[0097] The method for measuring the solubility will be described in detail in the Examples below.

[0098] The hydroxyl value of the ester compound is, for example, 0.5 mgKOH / g or less, or preferably 0.1 mgKOH / g or less.

[0099] The hydroxyl value of the ester compound can be measured according to the acetylation method or phthalation method in accordance with Method A or Method B of JIS K1557-1.

[0100] The acid value of the ester compound is, for example, 0.5 mgKOH / g or less, or preferably 0.1 mgKOH / g or less.

[0101] The acid value of the ester compound can be measured in accordance with JIS K 0070-1992 (potentiometric titration method).

[0102] The iodine value of the ester compound is, for example, 0.1 g / 100 g to 100 g / 100 g, or preferably 40 g / 100 g to 80 g / 100 g.

[0103] The iodine value of the ester compound can be measured in accordance with JIS K0070.

[0104] The ester compounds can be used alone or in combination of two or more.

[0105] The content of the ester compound will be described later.

[0106] In the above description, either the carboxylic acid or the alcohol in the diester compound is monofunctional, but both the carboxylic acid and the alcohol may be bifunctional. Specifically, the diester compound may be a reaction product of a dicarboxylic acid and a diol. In other words, the number of functional groups in the carboxylic acid and the alcohol is not limited as long as the carboxyl groups in the carboxylic acid and the hydroxyl groups in the alcohol are equal in amount. This also applies to triester compounds and tetraester compounds.

[0107] <Mineral oil> The flow improver may contain a mineral oil as needed. If the flow improver contains a mineral oil, the flow improver can be bulked up while maintaining the flow improving effect, thereby improving productivity.

[0108] Mineral oil is oil obtained by separating, distilling, and refining natural crude oil.

[0109] Examples of mineral oils include paraffinic hydrocarbons and naphthenic hydrocarbons, and preferably paraffinic hydrocarbons.

[0110] Mineral oils can be used alone or in combination of two or more types.

[0111] The content of mineral oil will be described later.

[0112] <Method of manufacturing flow improver> The flow improver can be obtained by mixing an ester compound with a mineral oil, which is optionally blended.

[0113] When the flowability improver contains an ester compound and a mineral oil, the content of the ester compound relative to the ester compound and the mineral oil is, for example, 20% by mass to 99% by mass, preferably 30% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, even more preferably 60% by mass to 88% by mass, and particularly preferably 75% by mass to 85% by mass.

[0114] Specifically, the content of the ester compound relative to the ester compound and the mineral oil is, for example, 20% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 75% by mass or more, and for example, 99% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 88% by mass or less, particularly preferably 85% by mass or less.

[0115] When the content of the ester compound is equal to or more than the above lower limit and equal to or less than the above upper limit, the fluidity can be further improved.

[0116] The content of the mineral oil relative to the ester compound and the mineral oil is, for example, 1% by mass to 80% by mass, preferably 5% by mass to 70% by mass, more preferably 10% by mass to 50% by mass, even more preferably 12% by mass to 40% by mass, and particularly preferably 15% by mass to 25% by mass.

[0117] Specifically, the content of the mineral oil relative to the ester compound and the mineral oil is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, particularly preferably 15% by mass or more, and for example, 80% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, particularly preferably 25% by mass or less.

[0118] When the content of the mineral oil is equal to or greater than the lower limit, the flowability improver can be increased in volume while maintaining the effect of improving flowability, thereby improving productivity.

[0119] If the content of the mineral oil is equal to or less than the upper limit, the viscosity change of the mineral oil due to the temperature change can be suppressed, and as a result, the reliability can be improved.

[0120] This produces a flow improver.

[0121] 2.Method for improving the fluidity of raw materials for steelmaking In the method for improving the fluidity of raw materials for iron making, a flowability improver is blended with the raw materials for iron making. Specifically, the raw materials for iron making and the flowability improver are mixed together using a known mixing device (a mill, a kneader, a mixer) and / or a raw material transfer system (a conveyor, a chute, a liner, a grate).

[0122] As for the kneading conditions, the kneading time is, for example, 1 minute to 120 minutes.

[0123] The blending ratio of the flowability improver relative to the total amount of the ironmaking raw materials and the flowability improver is, for example, 0.010 mass% to 2.000 mass%, preferably 0.050 mass% to 1.300 mass%, more preferably 0.100 mass% to 0.900 mass%, even more preferably 0.120 mass% to 0.600 mass%, and particularly preferably 0.140 mass% to 0.480 mass%.

[0124] Specifically, the blending ratio of the flow improver is, for example, 0.010% by mass or more, preferably 0.050% by mass or more, more preferably 0.100% by mass or more, even more preferably 0.120% by mass or more, particularly preferably 0.140% by mass or more, and for example, 2.000% by mass or less, preferably 1.300% by mass or less, more preferably 0.900% by mass or less, even more preferably 0.600% by mass or less, particularly preferably 0.480% by mass or less.

[0125] When the blending ratio of the flowability improver is equal to or greater than the lower limit, the flowability can be improved.

[0126] When the blending ratio of the flowability improver is equal to or less than the upper limit, stickiness caused by the flowability improver can be suppressed, and flowability can be improved.

[0127] In the method for improving the fluidity of raw materials for iron making, a flowability improver is blended with the raw materials for iron making, thereby improving the fluidity.

[0128] In the above explanation, the flowability improver is produced in advance by mixing the ester compound with the mineral oil, which is added as needed, and then this flowability improver is added to the raw materials for ironmaking. However, when the flowability improver is used, the ester compound and the mineral oil, which is added as needed, can also be added to the raw materials for ironmaking.

[0129] 3. Ironmaking method The ironmaking method includes a first step of carbonizing a first ironmaking raw material containing coal to produce coke, a second step of sintering a second ironmaking raw material containing iron ore to produce sintered ore, and a third step of producing steel from the coke and sintered ore.

[0130] In this iron-making method, a flowability improver is blended into the first iron-making raw material in the first step and / or the second iron-making raw material in the second step.

[0131] In the following explanation, a case where a flowability improver is blended with both the first iron-making raw material in the first step and the second iron-making raw material in the second step will be described in detail.

[0132] <1st process> In the first step, the first ironmaking raw material is carbonized to produce coke.

[0133] To produce coke by carbonizing the first ironmaking raw material, first, a flowability improver is blended with the first ironmaking raw material in the first step.

[0134] The first iron-making raw materials include at least coal, and preferably include coal and collected dust.

[0135] In the first step, the blending ratio of the flowability improver to the total amount of the first ironmaking raw material and the flowability improver is the same as the blending ratio of the flowability improver to the total amount of the ironmaking raw material and the flowability improver described above.

[0136] Next, the first ironmaking raw materials are carbonized to produce coke. Specifically, the first ironmaking raw materials are transported to a coke oven, and the first ironmaking raw materials are carbonized in the coke oven under known conditions to produce coke.

[0137] <Second process> In the second step, the second ironmaking raw material containing iron ore is sintered to produce sintered ore.

[0138] To produce sintered ore by sintering the second iron-making raw materials, first, a flowability improver is blended with the second iron-making raw materials in the second step.

[0139] The second iron-making raw materials include at least iron ore, and preferably include limestone, quicklime, and collected dust in addition to iron ore.

[0140] In the second step, the blending ratio of the flowability improver to the total amount of the second ironmaking raw materials and the flowability improver is the same as the blending ratio of the flowability improver to the total amount of the ironmaking raw materials and the flowability improver described above.

[0141] Next, the second ironmaking raw materials are sintered to produce sintered ore. Specifically, the second ironmaking raw materials are transported to a sintering furnace, and the second ironmaking raw materials are sintered in the sintering furnace under known conditions to produce sintered ore.

[0142] <3rd process> In the third process, steel is produced from the coke and sintered ore.

[0143] Specifically, the coke and sintered ore are transported to a blast furnace to produce pig iron under known conditions, and the pig iron is then transported to a converter to produce steel under known conditions.

[0144] In this iron-making method, a flowability improver is blended into the first iron-making raw material in the first step and the second iron-making raw material in the second step, thereby improving the flowability.

[0145] In the above explanation, the flowability improver is blended into both the first iron-making raw material in the first step and the second iron-making raw material in the second step, but the flowability improver can also be blended into either the first iron-making raw material in the first step or the second iron-making raw material in the second step. In more detail, the flowability improver can be blended not into the first iron-making raw material in the first step and blended into the second iron-making raw material in the second step, or the flowability improver can be blended not into the second iron-making raw material in the second step and blended into the first iron-making raw material in the first step.

[0146] Furthermore, in the above description, the ironmaking method is carried out in the order of the first step, the second step, and the third step, but the order is not limited as long as the first step and the second step are carried out before the third step.

[0147] Specifically, the second step, the first step and the third step may be carried out in this order, or the first and second steps may be carried out simultaneously, followed by the third step.

[0148] 4. Effects The flow improver contains an ester compound, and the ester compound has a flash point of 250°C or higher and a kinematic viscosity at 40°C of 1.0 x 10 -4 m 2 / s or less, and the solubility of the ester compound in water at 25°C is less than 1 g / 100 g. Therefore, the fluidity can be improved.

[0149] Specifically, when raw materials for ironmaking arrive at and are stored in a raw material storage area, moisture adheres to the raw materials, which reduces the fluidity of the raw materials, resulting in a problem of reduced productivity. Furthermore, raw materials for ironmaking are transported using transport equipment (e.g., conveyors, chutes, liners, grates, and hoppers), but the raw materials stick to the transport equipment, resulting in a problem of reduced transportability. Therefore, methods for improving the fluidity of raw materials for ironmaking are being considered.

[0150] As a method for improving the fluidity of raw materials for iron making, a method of drying the moisture adhering to the raw materials for iron making is being considered.

[0151] However, drying the moisture adhering to the raw materials for iron making requires a certain amount of time and / or large-scale equipment, which reduces productivity.

[0152] Furthermore, as a method for improving the fluidity of raw materials for iron making, a method of molding the raw materials for iron making in advance has been investigated.

[0153] However, this method has the disadvantage of reducing productivity because the raw materials for iron making must be shaped in advance.

[0154] In addition, as a method for improving the fluidity of raw materials for iron making, a method of blending heavy oil with the raw materials for iron making is being considered.

[0155] However, heavy oil has the disadvantage of having a low flash point.

[0156] Furthermore, as a method for improving the fluidity of raw materials for iron making, a method of blending surfactants with the raw materials for iron making is being considered.

[0157] However, from the viewpoint of further improving productivity, further improvement in fluidity is required.

[0158] In contrast, flow improvers can improve the flowability of raw materials for iron making simply by adding them, thereby improving productivity.

[0159] The flow improver contains an ester compound, and the ester compound has a flash point of 250°C or higher and a kinematic viscosity at 40°C of 1.0 x 10 -4 m 2 / s or less, and the solubility of the ester compound in water at 25°C is less than 1 g / 100 g.

[0160] That is, the flow improver comprises an ester oil having a high flash point and a low kinematic viscosity.

[0161] Such ester oil can coat the surface of the raw materials for iron making, thereby improving the fluidity of the raw materials for iron making.

[0162] Furthermore, the flow improver improves the flowability of the raw materials for iron making, thereby improving the bulk density of the raw materials for iron making.

[0163] On the other hand, by increasing the bulk density of the iron-making raw materials, the strength of the coke and iron ore obtained from the iron-making raw materials can also be improved. [Example]

[0164] The present invention will be described in more detail below with reference to examples and comparative examples. It should be noted that the present invention is in no way limited to these examples and comparative examples. The specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(numeric values ​​defined as "equal to or less than" or "less than") or lower limit values ​​(numeric values ​​defined as "equal to or greater than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the "Description of the Invention" above.

[0165] <Ingredient details> The trade names and abbreviations of the components used in each example and comparative example are detailed below. Isotridecyl oleate: Flash point 250°C or higher, kinematic viscosity (40°C) 0.14 x 10 -4 m 2 / s, solubility in water at 25°C less than 1g / 100g, acid value less than 0.5mgKOH / g, hydroxyl value less than 0.5mgKOH / g, commercially available Neopentyl glycol dioleate: Flash point 250°C or higher, kinematic viscosity (40°C) 0.18 x 10 -4 m 2 / s, solubility in water at 25°C less than 1g / 100g, acid value less than 0.5mgKOH / g, hydroxyl value less than 0.5mgKOH / g, commercially available Trimethylolpropane trioleate: Flash point 270°C or higher, kinematic viscosity (40°C) 0.47 x 10 -4 m 2 / s, solubility in water at 25°C less than 1g / 100g, acid value less than 0.5mgKOH / g, hydroxyl value less than 0.5mgKOH / g, commercially available Pentaerythritol tetraoleate: Flash point 300°C or higher, kinematic viscosity (40°C) 0.68 x 10 -4 m 2 / s, solubility in water at 25°C less than 1g / 100g, acid value less than 0.5mgKOH / g, hydroxyl value less than 0.5mgKOH / g, commercially available K68: Paraffin-based mineral oil, product name "Super Oil K68", manufactured by ENEOS Corporation BJ100: Paraffinic mineral oil, product name "Shell Morina S1 BJ 100", manufactured by Shell Alscope DA-330S: Anionic surfactant, polyoxyethylene alkyl (C12, 13) ether sodium sulfate (3E.O.), product name "Alscope DA-330S," solubility in water at 25°C of 1g / 100g or more, manufactured by Toho Chemical Co., Ltd. Finesurf 230: Nonionic surfactant, polyoxyethylene secondary alcohol ether (3E.O.) Product name: Finesurf 230, solubility in water at 25°C of 1g / 100g or more, manufactured by Aoki Oil & Fat Co., Ltd.

[0166] <Production of flow improver> Examples 1 to 14 and Comparative Examples 1 to 5 200 g (moisture content 9.5%) of powdered coal (steel raw material) that had passed through a sieve (mesh opening 3 mm) was mixed with the components (ester compound, mineral oil, anionic surfactant, nonionic surfactant, and oleic acid) based on the formulation shown in Table 1, and the mixture was kneaded for 1 minute using a pot mixer.

[0167] This resulted in a kneaded product containing the flowability improver and coal. The numerical values ​​for each component in Table 1 indicate the blending ratio of each component to the total amount of coal and each component.

[0168] Examples 15 to 17 and Comparative Example 6 Each component was mixed with 100 g (moisture content 9.5%) of powdered coal (steel raw material) that had passed through a sieve (mesh opening 3 mm) based on the formulation shown in Table 2, and the mixture was kneaded for 1 minute using a pot mixer.

[0169] This resulted in a kneaded product containing the flowability improver and coal. The numerical values ​​for each component in Table 2 indicate the blending ratio of each component to the total amount of coal and each component.

[0170] Examples 18 to 20 and Comparative Example 7 200 g (moisture content 9.5%) of powdered iron oxide (ironmaking raw material) that had passed through a sieve (mesh opening 3 mm) was mixed with each component based on the formulation shown in Table 2 and kneaded for 1 minute using a pot mixer. The iron oxide is a substitute for iron ore and collected dust, and contains divalent iron and trivalent iron.

[0171] This resulted in a kneaded material containing the flowability improver and iron oxide.The numerical value of each component in Table 2 indicates the blending ratio of each component to the total amount of iron oxide and each component.

[0172] <Evaluation> (flash point) The flash points of the ester compounds of the examples were measured using a Cleveland open cup flash point tester, and the results are shown in Tables 1 and 2.

[0173] (Kinematic viscosity) The kinematic viscosity at 40°C of the ester compound of each example was measured in accordance with JIS K 2283. The results are shown in Tables 1 and 2.

[0174] (Solubility in water at 25°C) The solubility in water at 25°C was measured for the ester compound of each Example and the surfactant of each Comparative Example. Specifically, in an environment of 25°C, 19.80 g of water was placed in a lidded test tube, and 0.20 g of a sample (the ester compound of each Example and the surfactant of each Comparative Example) was added to the water. The mixture was shaken 100 times and allowed to stand for 1 hour. Thereafter, the upper part of the liquid surface was visually observed. If an oil film remained on the upper part of the liquid surface, the solubility in water at 25°C was determined to be less than 1%. On the other hand, if no oil film remained on the upper part of the liquid surface, the solubility in water at 25°C was determined to be 1% or more. The results are shown in Tables 1 and 2.

[0175] (Liquidity) [Bulk density] The experimental conditions were 20°C and humidity 60%. First, a funnel was prepared and the bottom opening was plugged. Next, the kneaded materials of Examples 1 to 14 and Comparative Examples 1 to 5 were poured into the top opening (diameter 12 cm) of the funnel. Specifically, the kneaded materials were poured in until the height reached 45 cm from the bottom opening.

[0176] Next, a cylindrical stainless steel cup (height 10 cm, diameter 5 cm) was prepared. The upper end opening of the cylindrical stainless steel cup was connected to the lower end opening of the funnel, and the plug at the lower end opening of the funnel was removed. This caused the kneaded material in the funnel to freely fall toward the cylindrical stainless steel cup. At this time, part of the kneaded material overflowed from the upper end opening of the cylindrical stainless steel cup. Next, the kneaded material overflowing from the upper end opening of the cylindrical stainless steel cup was scraped off using a spatula with a length of 15 cm. Next, the mass of the cylindrical stainless steel cup containing the kneaded material was measured, and the bulk density was calculated from the volume of the cylindrical stainless steel cup.

[0177] The above procedure was carried out a total of 10 times. The bulk density improved with each repetition. This is presumably because the coal and flowability improver were gradually mixed during the above procedure, resulting in an increase in the amount of flowability improver coating the coal surface.

[0178] Then, at the 10th time, the bulk density stopped improving. From this, it is inferred that the coal and the flowability improver were sufficiently mixed at the 10th time. For the evaluation of bulk density, the 10th time, at which the coal and the flowability improver were sufficiently mixed, was used.

[0179] Separately, as a blank test, the above procedure was carried out 10 times using 200 g of coal only (coal not containing a flowability improver). As a result, the test conditions for the blank test were the same as the test conditions for the 10th bulk density test in Examples 1 to 14 and Comparative Examples 1 to 5.

[0180] From the bulk density of the 10th blank test, the increase rate of the bulk density at the 10th time was calculated for Examples 1 to 14 and Comparative Examples 1 to 5. It can be seen that a higher increase rate of the bulk density indicates better fluidity.

[0181] [Classification test] The experimental conditions were 20°C and 60% humidity. First, in Examples 15 to 20 and Comparative Examples 6 and 7, the retention rate (particle size distribution) of the ironmaking raw materials (the ironmaking raw materials before blending each component) on each sieve was measured in advance. Specifically, the ironmaking raw materials were classified using a sieve with a 1 mm mesh size and a sieve with a 300 μm mesh size, in that order. For classification, the sieves were struck and vibrated 100 times from the side. Then, the mass of the ironmaking raw materials on the 1 mm sieve, the mass of the ironmaking raw materials on the 300 μm sieve, and the mass of the ironmaking raw materials below the 300 μm sieve were measured. The retention rate on each sieve was then calculated based on the following formulas (1) to (3). Retention rate on 1 mm sieve = (mass of raw materials on 1 mm sieve / total mass of raw materials) × 100 (1) Retention rate on the 300 μm sieve = (mass of raw materials on the 300 μm sieve / total mass of raw materials) × 100 (2) Retention rate under the 300 μm sieve = (mass of ironmaking raw materials under the 300 μm sieve / total mass of ironmaking raw materials) × 100 (3)

[0182] Next, all the raw materials for iron making were collected, and the components were blended and mixed as described above to produce a kneaded product containing the flowability improver and the raw materials for iron making. Next, the remaining ratio of the kneaded product on each sieve was measured according to the same procedure as described above.

[0183] The increase / decrease rate of the retention rate for each sieve was calculated based on the following formulas (4) to (6). The results are shown in Table 2. It can be seen that a higher increase / decrease rate of the retention rate for the 300 μm sieve indicates that adhesion of the raw materials to each other is suppressed and that the flowability is excellent. Increase / decrease rate of residue on 1mm sieve = residue on 1mm sieve of kneaded material - residue on 1mm sieve of steelmaking raw material (4) Increase / decrease rate of residue on 300 μm sieve = residue on 300 μm sieve of kneaded material - residue on 300 μm sieve of steelmaking raw material (5) Increase / decrease rate of residue under 300 μm sieve = residue under 300 μm sieve of kneaded material - residue under 300 μm sieve of steelmaking raw material (6)

[0184] Table 2 also shows, as Reference Example 1, the retention rate on each sieve and the rate of increase or decrease in the retention rate on each sieve when coal is classified twice without using a flowability improver. Table 2 also shows, as Reference Example 2, the retention rate on each sieve and the rate of increase or decrease in the retention rate on each sieve when iron oxide is classified twice without using a flowability improver.

[0185] [Table 1]

[0186] [Table 2]

Claims

1. Contains an ester compound, The flash point of the ester compound is 250°C or higher, The ester compound has a kinematic viscosity at 40°C of 1.0 x 10 －４ m ２ / s or less, The flowability improver for raw materials for iron and steel making, wherein the ester compound has a solubility in water at 25°C of less than 1 g / 100 g.

2. The flowability improver for raw materials for iron making according to claim 1, further comprising a mineral oil.

3. The fluidity improver for raw materials for iron making according to claim 1, wherein the ester compound is a monoester compound.

4. A method for improving the fluidity of raw materials for iron making, comprising blending the flowability improver for raw materials for iron making according to any one of claims 1 to 3 with raw materials for iron making.

5. a first step of producing coke by carbonizing a first ironmaking raw material containing coal; a second step of sintering the second ironmaking raw material containing iron ore to produce sintered ore; and a third step of producing steel from the coke and the sintered ore, 4. An iron-making method, comprising blending the flowability improver for iron-making raw materials according to claim 1 with the first iron-making raw material in the first step and / or the second iron-making raw material in the second step.

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