JP4133764B2 - Granulation method for sintered raw materials for iron making - Google Patents

Description

The present invention relates to a method for granulating a sintering raw material for iron making. More specifically, the present invention relates to a method for granulating a sintered raw material for iron making for granulating fine iron ore and the like in the production of sintered ore as a raw material for charging a blast furnace in the iron making process.

The iron making process is generally performed by charging sintered ore made of iron ore, lump ore, and pellets together with coke into a blast furnace. This sintered ore is pre-processed with sintering raw materials including iron ore, auxiliary raw materials, fuel, etc., filled in a sintering machine to a specific height to form a sintering bed, and then fired by firing the surface layer It is manufactured by doing. As a sintering machine, a downward suction type is usually adopted, and air necessary for sintering is circulated by suctioning from below the sintering raw material, and fuel is supplied downward from above the sintering raw material. By burning, the sintering raw material is sintered. For this reason, if the sintering raw material contains a lot of fine powder, the air permeability decreases due to clogging and the like, and the combustion rate of coke, which is the fuel, becomes slow, so the production efficiency of the sintered ore decreases. It becomes.

Therefore, in order to improve the air permeability in the sintering bed and improve the productivity, a pretreatment such as granulating the sintered raw material to form pseudo particles is performed. For example, granulation operations such as mixing iron ore as a raw material for sintering, auxiliary materials, fuel, and the like, adding a small amount of water, and stirring with a granulator are performed. The pseudo particles are generally particles in which fine particles of 0.5 mm or less are attached to the particles of 1 to 3 mm or more. The actions required for such granulation are to improve the quasi-granulating property in which fine particles adhere to the periphery of the core particles, and to make the quasi-particles difficult to collapse in the sintering process.
Recently, with the depletion of excellent agglomerates, the deterioration of powdered ore has also become severe, and the granulation properties of sintered raw materials tend to be worse than before. Technology that is highly effective is highly desired.

As a conventional granulation method of a sintering raw material, it is known to use a polymer compound such as polyacrylic acid as a binder for granulation of iron ore containing fine iron ore (for example, Patent Document 1, 2, 3 and 4). However, these technologies have room for improvement. That is, the sintering machine that sinters the sintering raw material adopts a downward suction type, and by sucking from below the sintering raw material, the air necessary for sintering is circulated and from above the sintering raw material downward. The raw material for sintering is sintered by burning the fuel. Here, the sintering raw material is ignited from above. Since the granulation property of coke is relatively low and the particle size is smaller than the average particle size of iron ore, the average content of coke in small particles or pseudo particles of small particle size becomes high. Normally, when charging pseudo particles from a drum feeder into a sintering bed, it is bent and inserted so that small particles are arranged in the upper layer via a sloping plate, etc., and the coke content in the upper layer of the sintering raw material layer is set. Higher to facilitate ignition from above. On the other hand, for example, when using a polymer compound such as polyacrylic acid as a binder for granulation of iron ore containing fine iron ore, if the granulation property of the sintered raw material is remarkably improved, the granulation property is compared. Granulate to low coke, coke adheres to large pseudo particles, and in the sintering bed, there are many in the lower layer of the sintering raw material layer, or is embedded in the adhering powder layer of pseudo particles, The coke content in the upper layer of the sintering raw material layer is lowered. As a result, the ignitability in the ignition furnace tends to be inferior, or the coke contained in the pseudo particles tends not to burn. Therefore, even when the granulating property of the sintered raw material is improved, a technique is required such that the fuel such as coke is deflected to the upper layer of the sintered raw material layer or is packaged into pseudo particles.
JP 59-50129 (page 1-3) JP-A-61-61630 (first page) JP 10-502417 A (page 1-3) International Publication No. 02/066688 pamphlet (pages 155-159)

The present invention has been made in view of the above situation, and is effective for granulating a sintered raw material for iron making, such as fine iron ore, in the production of sintered ore as a raw material for charging a blast furnace in the iron making process, Even when the granulation property of the sintering raw material for iron making is remarkably improved, the fuel such as coke is deflected to the upper layer of the sintering raw material layer to maintain and improve the ignitability of the sintering raw material layer. It aims at providing the granulation processing method of the sintering raw material for iron manufacture which can implement | achieve productivity of a sintered ore.

While the inventors have studied various methods for granulating the iron-making sintered raw material, when granulating the iron-making sintered raw material, fuel that requires coke and / or anthracite is also granulated. Focusing on the fact that it becomes difficult to maintain the ignition to the sintering raw material layer due to being embedded in the adhering powder layer of pseudo particles, part or all of coke and / or anthracite as a fuel, After the treatment with the hydrophobic substance, the fuel is preferably treated with one or more substances selected from the group consisting of a compound having a paraffin chain having 5 or more carbon atoms, a compound having a naphthene ring, a silicone and a fluorine-containing compound. It has been found that the granulation property of coke and the like drops selectively when added to granulated iron ore and granulated. Although the cause of this has not been clarified sufficiently, the hydrophobicity of coke and / or anthracite coal increases, making it difficult to granulate coke, and the particle size distribution of coke is directly reflected in the particle size distribution of the sintered raw material. The particle size distribution can be controlled. As a result, even when the sintering raw material for iron making is sufficiently granulated, it becomes difficult for the fuel to be housed, and the productivity of the sintering machine is remarkably improved. In addition, since the granulation property of coke can be controlled, the position of the fuel in the height direction of the sintered bed that is loaded with bending is improved, and the content of coke etc. in the upper layer of the sintering raw material layer is increased. The inventors have found that it is possible to sufficiently maintain and further improve the ignitability of the sintered raw material layer by the above, and have arrived at the present invention, conceiving that the above problems can be solved brilliantly. .

That is, the present invention is a method for granulating a sintered raw material for iron making containing fine iron ore in the presence of a fuel essentially containing coke and / or anthracite, and a method for granulating the sintered raw material for iron making Sintering for iron making comprising a step of granulating a fuel obtained by treating a part or all of coke and / or anthracite with a hydrophobic substance together with part or all of the remaining sintering raw material for iron making This is a raw material granulation method.
The present invention is also a method for granulating a sintered raw material for iron making containing fine iron ore in the presence of a fuel essentially comprising coke and / or anthracite coal, the method for granulating the sintered raw material for iron making described above Includes a step of granulating a fuel obtained by treating a part or all of coke and / or anthracite with a hydrophobic substance together with a part or all of the remaining sintering raw material for iron making, and This step is also a method for granulating a sintered raw material for iron making, which is performed in the presence of a polymer compound having at least one group selected from the group consisting of a carboxyl group, a sulfonic acid group and a salt thereof.
The present invention is described in detail below.

In the method for granulating a sintered raw material for iron making according to the present invention, the sintered raw material for iron making is granulated in the presence of a fuel essentially comprising coke and / or anthracite.
The sintered raw material for iron making in the present invention contains fine iron ore, and usually contains other iron ore, auxiliary raw materials, fuel and the like. The fine iron ore is an iron ore mainly having a particle size of approximately 10 mm or less that cannot be used as a blast furnace raw material as it is.

In the present invention, a fuel obtained by treating a part or all of coke and / or anthracite coal with a hydrophobic substance is granulated together with a part or all of the remaining sintered raw material for iron making. In this case, as the preparation of coke and / or anthracite treated with a hydrophobic substance, a method in which the hydrophobic substance is added to coke and / or anthracite and stirred is suitable. In addition, the coke and / or anthracite can be treated by a method of reducing the hydrophilic portion present in a small amount of coke and / or anthracite by adding a substance that reacts with a hydrophilic group and stirring the mixture. Part or all of the above may be subjected to a hydrophobic treatment. In addition, as a fuel in this invention, what contains the coke and / or anthracite processed by a hydrophobic substance should just be contained. As a stirring method, for example, a method of mixing with a pan pelletizer, a drum mixer, an Eirich mixer, a Laedige mixer, a rod mill, a ball mill, a roller mill, or the like is suitable.

In the case of preparing coke and / or anthracite treated with the above hydrophobic substance, the hydrophobic substance is preferably a substance having higher hydrophobicity than coke and / or anthracite and having 5 carbon atoms. It is preferable to include one or more substances selected from the group consisting of the above-mentioned compound having a paraffin chain, a compound having a naphthene ring, silicone and a fluorine-containing compound, and more preferably a compound having a paraffin chain having 5 or more carbon atoms. preferable. In this case, preferred embodiments of the present invention include a compound having a paraffin chain having 5 or more carbon atoms, a compound having a naphthenic ring, a silicone, and a fluorine-containing compound in advance in part or all of coke and / or anthracite as fuel. After adding 1 or more types of substances chosen from the group which consists of, it adds to the sintering raw material for iron making containing a fine iron ore, and the form granulated. That is, part or all of the fuel in the present invention is one or more selected from the group consisting of coke and / or anthracite, a compound having a paraffin chain having 5 or more carbon atoms, a compound having a naphthene ring, silicone, and a fluorine-containing compound. It is preferable that it contains a substance.

The use ratio of the hydrophobic substance ([mass of hydrophobic substance] / [mass of coke and / or anthracite]) is preferably 0.05 / 100 or more, and 10/100 or less. Is preferred. That is, it is preferable that the addition amount of a hydrophobic substance is 0.05-10 mass% with respect to 100 mass% of coke and / or anthracite. If it is less than 0.05 / 100, the effect of selectively lowering the granulation property of the fuel and maintaining the ignition of the sintering raw material layer is hardly further improved. As the cost increases, the granulation property of the sintered raw material for iron making may be lowered. More preferably, it is 0.1 / 100 or more and 3/100 or less.
The mass of the hydrophobic substance, coke and / or anthracite is the total mass used in the present invention, that is, the mass of coke and / or anthracite added simultaneously with the hydrophobic substance, and before the addition of the hydrophobic substance. The mass of coke and / or anthracite blended (added) with the mass of coke and / or anthracite added after the hydrophobic substance is added.

As the compound having a paraffin chain having 5 or more carbon atoms, paraffins, isoparaffins and the like are suitable. For example, n-hexane, isohexane, n-decane, n-dodecane, isododecane, n-hexadecane and the like and these Compounds having a structure are preferred. In the present invention, the compound having a paraffin chain having 5 or more carbon atoms means other functional groups such as a vinyl group, a hydroxyl group, a carboxylic acid ester group, an ether group as long as it has a paraffin chain having 5 or more carbon atoms. Amide group, imide group, sulfonic acid ester group, amino group, aldehyde group, isocyanate group and the like. For example, octadecene, octadecyl alcohol, octadecyl isocyanate, octadecyl aldehyde, octadecyl vinyl ether, octadecyl mercaptan and the like are suitable.

As the compound having a naphthene ring, cyclopentane, cyclohexane, cyclooctane and the like and compounds having these structures are suitable. From the viewpoint of safety, the compound having a paraffin chain and the compound having a naphthene ring preferably have a flash point of 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 65 ° C. or higher. In addition, as said compound, even if a flash point is less than a preferable range, if it can fully exhibit the effect of this invention, it can use suitably.
The compound having a paraffin chain and the compound having a naphthene ring may be used alone, but it is economically preferable to use as a mixture of several kinds, for example, paraffin oil, liquid paraffin, paraffin wax, asphalt, heavy oil Oil-based lubricating oils such as spindle oil, refrigeration oil, compressor oil, dynamo oil, turbine oil, machine oil, engine oil, cylinder oil, marine engine oil, gear oil, aviation lubricating oil; animal oil and vegetable oil, etc. Is preferred. In addition, waste oil of edible oil discharged in the food industry, restaurant industry, general households, etc., and recycled oil obtained by removing or refining these impurities are preferred. Examples of the recycled oil include soybean oil, rapeseed oil, corn oil, palm oil, beef tallow recycled oil, and mixtures thereof. In addition, from the aspect of suppressing coke interior and maintaining ignition to the sintered raw material layer, liquid paraffin, crude oil fractions with a flash point of 65 ° C or higher, the above-mentioned petroleum-based lubricants, animal fats, vegetable oils, edible oils Waste oil and the above recycled oil are preferred, and liquid paraffin, edible oil waste oil and the above recycled oil are most preferred.

The silicone is a compound having an organopolysiloxane structure. In the present invention, the compound having the structure is not particularly limited, but a compound classified as silicone oil has high coke treatment efficiency. To preferred. Silicone oil is a mixture of various molecular weights mainly composed of linear dimethylpolysiloxane having a relatively low degree of polymerization.
The fluorine-containing compound may be any compound having a structure in which a fluorine atom is bonded to a carbon atom, but a compound having a tetrafluoroethylene structure is particularly preferable.

It is preferable that the fuel contains coke and / or anthracite and these are the main components. The amount of such fuel used varies depending on the properties of the raw material and the like, but is preferably 1 part by weight or more with respect to 100 parts by weight of the sintered raw material for iron making including fine iron ore, and 10 parts by weight. The following is preferable. If the amount is less than 1 part by weight, it may be difficult to maintain the ignition of the sintering material layer. If the amount exceeds 10 parts by weight, in the sintering bed, other than the surface layer of the sintering material layer, for example, the sintering material layer In the height direction, the coke content in the middle part and the lower part also tends to be high, so that the amount of heat becomes excessive at the time of sintering and the air permeability tends to deteriorate due to the increase in the melt. Furthermore, it is not preferable from the viewpoint of increasing the cost of fuel. More preferably, it is 2 parts by weight or more and 6 parts by weight or less. Note that the amount of fuel used here is the amount of all fuel used in the granulation process, and “the amount of all fuel used in the granulation process” is as described above. Further, the fuel containing coke and / or anthracite treated with the hydrophobic substance includes the mass of the hydrophobic substance.

Further, in the present invention, as the fuel, in addition to coke and / or anthracite, dust having a combustible carbon content of 5% by mass or more generated from inside and / or outside the ironworks, fine powder of coal or charcoal, etc. may be mentioned. It is done. With respect to the dust having a combustible carbon content of 5% by mass or more, since the carbon content varies, in the present invention, when calculating the mass as the fuel, the combustible carbon equivalent mass is used. To do. The mass in terms of carbon that can be combusted can be measured, for example, by applying a desired dust in place of the sieving portion of 1 mm or less of the pseudo particles in the “quantification of carbon content in the pseudo particles” of the examples. In the present invention, combustible carbon conversion is a carbon content obtained by subtracting a carbon content that cannot be used as a fuel such as carbon contained in limestone from the total carbon content. Accordingly, when the dust having a combustible carbon content of 5% by mass or more is treated with the hydrophobic substance of the present invention, when calculating the mass as the fuel, the combustible carbon equivalent mass contained in the dust And the total mass of the hydrophobic substance used. The timing of processing the fuel with the hydrophobic material may be any time as long as it is before the start of granulation, but it is added in the process of adjusting the particle size of the coke for sintering, for example, in the crushing process, or on the belt conveyor during transportation. The method is preferred.

The timing of mixing the fuel with a part or all of the remaining sintering raw material for iron making may be before the start of the granulation process, or until after the start of the granulation process. Also good. Mixing the fuel and a part or all of the remaining sintering raw material for iron making can be performed by adding fuel to a part or all of the remaining sintering raw material for iron making. In addition, the fuel may be mixed once in the iron-making sintered raw material, or may be mixed in a plurality of times.

The granulation treatment step is preferably performed in the presence of a polymer compound having at least one group selected from the group consisting of a carboxyl group, a sulfonic acid group and a salt thereof, and for iron making including fine iron ore A method of granulating a sintered raw material in the presence of a fuel essentially containing coke and / or anthracite, wherein the granulating method of the sintered raw material for iron making is part or all of coke and / or anthracite Including a step of granulating a fuel obtained by treating the fuel with a hydrophobic substance together with a part or all of the remaining sintering raw material for iron making, and the step of granulating includes a carboxyl group, a sulfonic acid group, and these A method for granulating a sintered raw material for iron making performed in the presence of a polymer compound having at least one group selected from the group consisting of the above salts is also one aspect of the present invention.
The form of using such a polymer compound is not particularly limited, and may be added to the iron-making sintering raw material once at the time of granulation, or may be added in a plurality of times. In addition to the polymer compound, a granulating agent as described below may be used in combination as the granulating agent. The granulation treatment agent means a compound or the like used for improving the granulation property when granulating a sintered raw material for iron making.
As the granulation method in the present invention, a granulation method using the same apparatus as the mixing method in the preparation of coke and / or anthracite treated with a hydrophobic substance is suitable.

The amount of the polymer compound used may be set as appropriate depending on the granulation properties of the sintering raw material, the type of the polymer compound, the type of equipment used, and the like. The polymer compound is preferably 0.001 part by weight or more, more preferably 2 parts by weight or less, based on 100 parts by weight of the starting material. If the amount is less than 0.001 part by weight, the effect of the present invention may not be sufficiently exhibited without being sufficiently granulated. If the amount exceeds 2 parts by weight, the polymer for the sintering raw material for iron making There is a possibility that the amount of the compound added becomes excessively large, and the sintered raw material for iron making becomes large and becomes difficult to sinter. More preferably, the polymer compound is 0.003 parts by weight or more and 1 part by weight or less.

As a granulating agent other than the above polymer compound, one or more kinds of quicklime, bentonite, lignin sulfite (pulp waste liquor), starch, sugar, molasses, water glass, cement, gelatin, corn starch and the like are used. it can.
As the usage-amount of the said granulation processing agent, it is preferable to set it as 0.05 weight part or more with respect to 100 weight part of sintering raw materials for iron manufacture containing a fine iron ore, and it shall be 3 weight part or less. preferable. More preferably, it is 0.1 parts by weight or more and 2 parts by weight or less.

In the above granulation treatment step, the granulation treatment may be performed using fine particles having an average particle size of 200 μm or less in combination for the purpose of preventing the granulated material from collapsing in a sintered bed or the like. The fine particles may be fine particles having the above average particle diameter, but calcium carbonate, kaolin clay, silica, silica sand, talc, bentonite, dolomite powder, dolomite plaster, magnesium carbonate, silica fume, anhydrous gypsum, sericite , Montmorillonite, shirasu, shirasu balloon, diatomaceous earth, calcined diatomaceous earth, silicon carbide, yellow iron oxide, strontium carbonate, barium carbonate, graphite, wollastonite, crecas sphere, carbon black, bengara, crushed serpentine, activated clay, portland cement , Ground silica, ground serpentine, magnesium oxide, baked Dust generated in processes other than leech stone and steelworks, specifically dust generated in thermal power plants such as fly ash and heavy oil ash, calami iron concentrate, copper slag, and alumina production processes generated in the coppermaking process In addition, red mud discharged in the above, flue gas desulfurization gypsum, asbestos dust and the like are suitable, and one or more kinds can be used. Preferably, it is at least one selected from the group consisting of calcium carbonate, fly ash, kaolin clay, silica, talc, bentonite, silica fume, and anhydrous gypsum.

The average particle diameter of the fine particles having an average particle diameter of 200 μm or less is preferably 0.01 μm or more, and preferably 100 μm or less. More preferably, it is 0.02 μm or more and 50 μm or less. Most preferably, it is 0.1 μm or more and 20 μm or less.
When the average particle diameter exceeds 200 μm, the ratio of large particles to which fine particles adhere is larger than the ratio of fine particles with the effect of suppressing the collapse of pseudo particles in a sintered bed or the like. It becomes difficult to be. On the other hand, when the thickness is less than 0.01 μm, the cohesive force of the fine particles becomes strong and it is difficult to disperse in the raw material for iron making.

The amount of the fine particles having an average particle diameter of 200 μm or less is preferably 0.1 parts by weight or more, and 10 parts by weight or less with respect to 100 parts by weight of the sintered raw material for iron making including fine iron ore. It is preferable to do. More preferably, it is 0.3 parts by weight or more and 1.5 parts by weight or less.
When the amount is less than 0.1 part by weight relative to 100 parts by weight of the raw material for iron making, it is difficult to obtain the effect of suppressing the collapse of the granulated product. Therefore, there is a risk that the manufacturing cost is wasted.

In the method for granulating a sintering raw material for iron making according to the present invention, sintering can be performed without the influence of coke interior or the like, which is a problem when sufficiently sintering the sintering raw material for iron making using the above polymer compound. For example, it is possible to sufficiently maintain the ignition of the sintered raw material layer. For example, as the granulation property, the GI index of a granulated product (pseudoparticle) having a particle size of 0.25 mm or less is 80 or more. It is preferable to improve the productivity of the sintering machine. More preferably, the GI index is 85 or more, and still more preferably 90 or more.
The GI index is one of evaluation methods disclosed in Steel Manufacturing Research No. 288 (1976), page 9, and represents the ratio of fine particles adhering around the core particles. The GI index was measured by drying the pseudo particles obtained by granulation operation at 80 ° C. for 1 hour and then classifying them using a sieve to obtain the particle size (pseudo particle size). No. (1976), page 9, and can be calculated by the following formula.
GI index = {(ratio of raw material of 0.25 mm or less before granulation−ratio of raw material of 0.25 mm or less after granulation) / (ratio of raw material of 0.25 mm or less before granulation)} × 100

Further, as the pseudo particles which are the granulated product obtained in the present invention, the carbon content (coke content) of the pseudo particles of 1 mm or less is preferably 3% by mass or more, and 3.5% by mass or more. More preferably. When a polymer compound, particularly a polymer compound having at least one group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a salt thereof is used as the granulating agent, it is preferably within the above range. .
The carbon content of the pseudo particles having a size of 1 mm or less is preferably measured by the following method. First, a sifted portion of 1 mm or less of the pseudo particles is mixed, and the whole amount is pulverized by a pulverizer such as a mill. About 1 g of pseudo particles after pulverization are collected in a container, and the mass is accurately measured (assumed to be Ag). Add 10 g of distilled water to lightly adjust, and add 1.2 g to 1.3 g of phosphoric acid to remove carbon contained in limestone out of the system as carbon dioxide. After being shaken by hand, it is sufficiently dried in a vacuum dryer set at 135 ° C. The contents are removed from the container, transferred to a mortar, crushed, and dried in an oven at 130 ° C. The mass of this dried product is measured (referred to as Bg). The amount of C (carbon) in the dried product is determined by elemental analysis (C%). The amount of carbon (coke amount) contained in the pseudo-ladder of 1 mm or less is calculated as follows.
Amount of coke contained in pseudo particles of 1 mm or less (%) = B (g) × C (%) / A (g)
In the present invention, the carbon content is a carbon content obtained by subtracting carbon that cannot be used (not burned) as a fuel such as carbon contained in limestone from the total carbon content.

The granulated product obtained by the granulation treatment method for the iron-making sintered raw material of the present invention can be sintered by a sintering machine to form a sintered ore. A sintered ore produced from such a granulated product obtained by the method for granulating a sintering raw material for iron making according to the present invention is one of the preferred embodiments of the present invention. Such a sintered ore improves the granulation property of the granulated material obtained in the method for granulating a sintered raw material for iron making according to the present invention, that is, the granulating property of the sintered raw material for iron making, and at the same time ignites the sintered raw material layer. It is useful to be produced from a granulated material that can maintain sufficient productivity of the sintered ore.

The productivity of sintered ore production in the present invention can be measured by the product yield and production rate of the sintered ore. For example, the product yield can be measured by sintering after sintering in the sintering pot test. It can be evaluated by measuring the proportion of particles having a particle size of 5 mm or more when 50 kg of ore (sinter cake) is dropped 5 times onto a steel plate from a height of 2 m. The production rate can be calculated by the following equation.
Production rate (t / day / m ² ) = total mass of particles having a particle size of 5 mm or more after product yield evaluation (t) / sintering time (day) / surface area of sintering machine (pan) (m ² )

Below, the high molecular compound which has at least 1 type of group selected from the group which consists of a carboxyl group in this invention, a sulfonic acid group, and these salts is demonstrated. In the polymer compound, a salt of a carboxyl group or a sulfonic acid group is a group having a structure in which a hydrogen atom in a carboxyl group or a sulfonic acid group is replaced with a metal atom or the like, and means a group in the form of a salt. To do.

Examples of the polymer compound include (1) a polymer compound having a carboxyl group and / or a salt thereof, (2) a polymer compound having a sulfonic acid group and / or a salt thereof, and (3) a carboxyl group and / or a salt thereof. , And any one or more of polymer compounds having a sulfonic acid group and / or a salt thereof. As such a polymer compound, at least one monomer selected from the group consisting of a monomer having a carboxyl group, a monomer having a sulfonic acid group, and a monomer having a salt thereof is essential. What can be obtained by superposing | polymerizing with the monomer composition made into is preferable. Such monomers can be used singly or in combination of two or more, but more preferably, (1) a monomer having a carboxyl group and / or its relative to 100 mol% of the total monomer composition A monomer composition containing at least one of a monomer having a salt and (2) a monomer having a sulfonic acid group and / or a monomer having a salt thereof in an amount of 10 mol% or more. It is. When the content of the monomer (1) and / or (2) in the monomer composition is less than 10 mol%, the granulation effect may not be sufficiently obtained in the selective granulation step. More preferably, it is 30 mol% or more, and particularly preferably 50 mol% or more. Among the more preferable polymer compounds described above, those obtained by polymerizing a monomer having a carboxyl group and / or a monomer having a salt thereof are more preferable. That is, the polymer compound is polymerized with a monomer composition containing 10 mol% or more of a monomer having a carboxyl group and / or a salt thereof with respect to 100 mol% of the total monomer composition. More preferably.

The monomer having a carboxyl group or a salt thereof has a carboxyl group such as (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, crotonic acid, acrylamide glycolic acid, etc. Monomers and their salts are preferred. These may be used alone or in combination of two or more. Among these, (meth) acrylic acid and / or a salt thereof is more preferable. That is, the polymer compound having a carboxyl group and / or a salt thereof in the present invention is preferably a polymer obtained by polymerization with a monomer composition mainly composed of (meth) acrylic acid and / or a salt thereof. More preferred is acrylic acid and / or a salt thereof. Moreover, as a salt, alkali metal salts, such as sodium and potassium; Alkaline earth metal salts, such as calcium and magnesium; Ammonium salt; Organic amici salts, such as monoethanolamine and triethanolamine, are suitable. Among these, alkali metal salts such as sodium and potassium, and ammonium salts are preferable, and sodium salts are more preferable.

Examples of the monomer having a sulfonic acid group or a salt thereof include sulfonic acid groups such as vinyl sulfonic acid, styrene sulfonic acid, sulfoethyl (meth) acrylate, and 2-acrylamido-2-methylpropane sulfonic acid. Preferred are monomers having a salt thereof and salts thereof. These may be used alone or in combination of two or more.

In addition to the monomer having a carboxyl group, the monomer having a sulfonic acid group, and the monomer having a salt thereof, the above monomer composition includes other copolymers that can be copolymerized with these monomers. 1 type (s) or 2 or more types may be included.
Examples of the other copolymerizable monomers include 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2 -Monomers having an acidic phosphate group such as (meth) acryloyloxyethylphenyl phosphate; monomers having an acid group such as a vinyl acid monomer such as vinylphenol, and salts thereof are preferred.

Examples of the other copolymerizable monomers also include polyalkylene glycol (meth) acrylates such as polyethylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, and methoxypolyethyleneglycol monoacrylate; Polyalkylene glycol monoalkenyl ether monomer formed by adding ethylene oxide to methyl-3-buten-1-ol; polyethylene glycol monoethenyl ether monomer formed by adding ethylene oxide to allyl alcohol; A monomer having a polyalkylene glycol chain such as maleic acid polyethylene glycol half ester to which polyethylene glycol has been added is preferred. Among these monomers having a polyalkylene glycol chain, a monomer having a polyalkylene glycol chain having a chain length of 5 mol or more and 100 mol or less in terms of ethylene oxide is easy to obtain, It is preferable from the viewpoints of improvement in polymerizability and polymerization. More preferably, it is a monomer having a polyalkylene glycol chain having a chain length of 10 mol or more and 100 mol or less in terms of ethylene oxide.

As said other copolymerizable monomer, the following compound can be used besides the thing mentioned above.
Methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylic acid (N, N-dimethylaminoethyl), (meth) acrylic acid (N, N-diethylaminoethyl) C1-C18 (meth) acrylic acid alkyl esters such as aminoethyl (meth) acrylate; (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (Meth) acrylamide and its derivatives such as (meth) acrylamide; vinyl acetate; (meth) acrylonitrile; base-containing monomers such as N-vinyl-2-pyrrolidone, vinylpyridine and vinylimidazole; N-methylol (meth) acrylamide , N-butoxymethyl (meth) acrylamide and other cross-linkability (Meth) acrylamide monomers; hydrolyzable groups such as vinyltrimethoxysilane, vinyltriethoxysilane, γ- (meth) acryloylpropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, allyltriethoxysilane A silane monomer in which is directly bonded to a silicon atom; a monomer having an epoxy group such as glycidyl (meth) acrylate, glycidyl ether (meth) acrylate; 2-isopropenyl-2-oxazoline, 2-vinyl-2 -Monomers having an oxazoline group such as oxazoline; monomers having an aziridin group such as 2-aziridinylethyl (meth) acrylate and (meth) acryloylaziridine; vinyl fluoride, vinylidene fluoride, vinyl chloride, chloride A monomer having a halogen group such as vinylidene; E) Esters of acrylic acid with polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol Polyfunctional (meth) acrylic acid ester having a plurality of unsaturated groups in the molecule such as fluoride; polyfunctional (meth) acrylamide having a plurality of unsaturated groups in the molecule such as methylenebis (meth) acrylamide; diallyl phthalate, diallyl maleate Polyfunctional allyl compounds having a plurality of unsaturated groups in the molecule, such as diallyl fumarate; allyl (meth) acrylate; divinylbenzene.

When (co) polymerizing the monomer, a chain transfer agent may be used for the purpose of adjusting the molecular weight. Examples of the chain transfer agent include compounds having a mercapto group such as mercaptoethanol, mercaptopropionic acid, t-dodecyl mercaptan; carbon tetrachloride; isopropyl alcohol; toluene; hypophosphorous acid, sodium hypophosphite, sodium bisulfite, etc. A compound having a high chain transfer coefficient is preferred. These may be used alone or in combination of two or more. The amount of the chain transfer agent used is preferably 0.005 to 0.15 mole per mole of monomer.

Methods for (co) polymerizing the above monomers include various conventionally known polymerization methods such as oil-in-water emulsion polymerization, water-in-oil emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation weight. A combination method, a solution polymerization method, an aqueous solution polymerization method, a bulk polymerization method and the like can be employed. Among these, the aqueous solution polymerization method is preferable from the viewpoint of reduction in polymerization cost (production cost) and safety.

The polymerization initiator used for the polymerization may be a compound that decomposes by heat or a redox reaction to generate radical molecules. Moreover, when performing superposition | polymerization by aqueous solution polymerization method, it is preferable to use the polymerization initiator provided with water solubility. Examples of the polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; 2,2′-azobis- (2-amidinopropane) dihydrochloride, 4,4′-azobis- (4-cyano Water-soluble azo compounds such as pentanoic acid; thermal decomposable initiators such as hydrogen peroxide; hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and Rongalite, potassium persulfate and metal salts, ammonium persulfate and sodium bisulfite A redox polymerization initiator comprising a combination of the above is preferred. These may be used alone or in combination of two or more. What is necessary is just to set suitably as the usage-amount of a polymerization initiator according to a monomer composition, polymerization conditions, etc. FIG.

The polymerization conditions such as the reaction temperature and reaction time in the above polymerization may be appropriately set according to the composition of the monomer, the type of the polymerization initiator, etc. The reaction temperature is 0 to 150 ° C. Is preferable, and it is more preferable to set it as 40-105 degreeC. The reaction time is preferably about 3 to 15 hours. As a method for supplying the monomer to the reaction system when the polymerization is performed by an aqueous solution polymerization method, a batch addition method, a divided addition method, a component dropping method, a power feed method, or a multistage dropping method can be used. The polymerization may be performed under normal pressure, reduced pressure, or increased pressure.

In the production of the polymer compound, the concentration of the non-volatile component containing the polymer compound contained in the polymer compound aqueous solution obtained when the aqueous solution polymerization method is adopted is preferably 70% by mass or less. When it exceeds 70 mass%, there exists a possibility that a viscosity may become high too much.

As the polymer compound having a sulfonic acid group and / or a salt thereof, β-naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, aromatic aminosulfonic acid polymer and the like can be used.

The polymer compound having at least one group selected from the group consisting of carboxyl groups, sulfonic acid groups and salts thereof in the present invention preferably has a weight average molecular weight of 1,000 to 1,000,000. If the weight average molecular weight is less than 1000, the action as a dispersant may be reduced. If it exceeds 1,000,000, the viscosity of the polymer compound becomes too high, and it may be difficult to add so that the action as a dispersant is sufficiently exhibited. More preferably, it is 3000 or more and 100000 or less. In the present specification, the weight average molecular weight is a value measured under the following measurement conditions.

(Weight average molecular weight measurement conditions)
Column: Aqueous GPC column “GF-7MHQ” (trade name, manufactured by Showa Denko KK) One carrier liquid: 34.5 g of disodium hydrogen phosphate dodecahydrate and 46.2 g of sodium dihydrogen phosphate dihydrate Ultrapure water is added to make the total amount 5000 g.
Aqueous solution flow rate: 0.5 ml / min
Pump: “L-7110” (trade name, manufactured by Hitachi, Ltd.)
Detector: Ultraviolet (UV) detector “L-7400” (trade name, manufactured by Hitachi, Ltd.), wavelength 214 nm
Molecular weight standard sample: sodium polyacrylate (sodium polyacrylate having a weight average molecular weight of 1300 to 1360000 available from Soka Kagaku)
The analysis sample is prepared by diluting with the carrier liquid so that the polymer compound is 0.1% by mass in solid content.
However, the following measurement conditions are applied to polymer compounds that cannot be measured under the above measurement conditions.
Model: Waters LCM1
Carrier solution: 115.6 g of sodium acetate trihydrate dissolved in a mixture of 10999 g of water and 6001 g of acetonitrile, and further adjusted to pH 6.0 with 30% aqueous sodium hydroxide solution Flow rate: 0.8 ml / min
Column: Water-based GPC column “TSKgel GuardColumnSWXL + G4000SWXL + G3000SWXL + G2000SWXL” (manufactured by Tosoh Corporation)
Column temperature: 35 ° C
Detector: Waters 410 Differential refraction detector Molecular weight standard sample: Polyethylene glycol The analytical sample is prepared by diluting with the carrier solution so that the polymer compound is 0.1% in solid content.

The polymer compound preferably has a dispersity of 12 or less. If the degree of dispersion exceeds 12, the action of dispersing fine iron ore tends to be small, and the action of making pseudo particles tends to decrease. More preferably, it is 10 or less. The degree of dispersion is the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn), and represents the molecular weight distribution. The number average molecular weight is measured by the same method as the weight average molecular weight.
These polymer compounds may be added in a solid form, but are preferably added in the form of an aqueous solution having a solid content concentration of 0.1 to 70%.

The method for granulating a sintered raw material for iron making according to the present invention comprises the above-described configuration, and is used for granulating a sintered raw material such as fine iron ore in the production of sintered ore as a raw material for charging a blast furnace in the iron making process It is effective and improves the granulation property of the sintering raw material for iron making, and at the same time, the fuel such as coke is deflected to the upper layer of the sintering raw material layer to maintain and improve the ignitability of the sintering raw material layer. Sinter ore productivity can be realized.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

The GI index, product yield, production rate, and carbon content (coke content) of pseudo particles in Examples and Comparative Examples were measured by the following methods.
(GI index of pseudo particles)
The pseudo particles obtained by the granulation operation were dried at 80 ° C. for 1 hour and classified using a sieve to obtain the particle size (pseudo particle size). The GI index of the granulated pseudo particles is one of the evaluation methods disclosed in Steel Manufacturing Research No. 288 (1976), page 9, and indicates the ratio of fine particles adhering around the core particles. The GI index was measured according to the method described in Steel Manufacturing Research No. 288 (1976), page 9.
In the measurement of each of the following Examples and Comparative Examples, the GI index of pseudo particles having a particle diameter after granulation of 0.25 mm or less was determined.
Moreover, the GI index (pseudo graining index) of pseudo particles of 0.25 mm or less was calculated by the following formula.
GI index = {(ratio of raw material of 0.25 mm or less before granulation−ratio of raw material of 0.25 mm or less after granulation) / (ratio of raw material of 0.25 mm or less before granulation)} × 100

(Product yield, production rate)
In the product yield, in the sintering pot test, 50 kg of sintered ore after sintering (sinter cake) was dropped 5 times on a steel plate from a height of 2 m. The ratio was evaluated by measuring. The production rate was calculated by the following formula.

The sintered raw materials and pellet raw materials in the examples and comparative examples described below were all in an absolutely dry state. The weight average molecular weight of the polymer in the polymer aqueous solution was measured by polyethylene glycol conversion by GPC (gel permeation chromatography).
(Quantification of carbon content in pseudo particles)
The sifted portion of 1 mm or less of the pseudo particles after the GI index measurement is mixed, and the whole amount is pulverized by a pulverizer such as a mill. At this time, the average particle size after pulverization is set to 50 μm or less. If there are too many sieving parts that cannot be pulverized at one time, pulverize them twice or more, and mix them uniformly after pulverization.
About 1 g of pseudo particles after pulverization are collected in a commercially available PP (polypropylene) container having a capacity of 120 ml, and the mass is accurately measured (assumed to be Ag). Add 10 g of distilled water and let it blend lightly. In order to remove carbon contained in limestone out of the system as carbon dioxide, 1.2 g to 1.3 g of phosphoric acid was added, and the container was shaken by hand while foaming was observed, and then heated to 135 ° C. Dry thoroughly with the set vacuum dryer. The contents are removed from the PP container, transferred to a mortar, crushed, and dried in an oven at 130 ° C. At this time, when the content does not become powder, it is pulverized and dried again after drying in an oven at 130 ° C. The mass of the content after drying (referred to as composition 1) is measured (referred to as Bg). The amount of C in the composition 1 is determined by elemental analysis (C%). The amount of carbon contained in pseudo particles of 1 mm or less is calculated as follows.
Amount of carbon contained in pseudo particles of 1 mm or less (%) = B (g) × C (%) / A (g)

[Example 1]
Powder coke having a particle size distribution shown in Table 1 is sieved with a 0.25 mm sieve, and 10000 parts under the sieve, and liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd.) (Coke modification) as a hydrophobic substance in the present invention. Agent 1) 200 parts was added and stirred with a mixer for 10 minutes. The treated coke was remixed with the top portion of the sieve at the same mass ratio as before sieving (the coke obtained by remixing the treated coke is referred to as treated coke 1). That is, the 0.25 mm under sieve in Table 1 was replaced with the same mass of treated coke.
Sintered raw materials (raw materials for iron making) having the composition shown in Table 2 were prepared. Here, the treated coke 1 was used as the powder coke.

70000 parts of the above-mentioned sintered raw material was put into a drum mixer, and 5250 parts of a sodium polyacrylate aqueous solution having a weight average molecular weight of 6000, which was prepared in advance to a non-volatile content of 0.4% as a dispersant in the composition (sintered raw material). Was sprayed (added) over 1.5 minutes using a spray bottle. The ratio of sodium polyacrylate to the sintering raw material was 0.03%. After spraying, the above-mentioned composition to which the dispersant was added (final composition for granulation treatment) was further stirred at the same rotational speed for 3 minutes to perform granulation treatment (pseudo granulation).
Further, from the obtained pseudo particles, about 1 kg was sampled uniformly, the contained moisture was measured, and the pseudo particles were dried and classified using a sieve to obtain the GI index of the pseudo particles. Furthermore, a portion of 1 mm or less of the pseudo particles after the GI index measurement was remixed, and the whole amount was pulverized using a hammer mill so that the average particle diameter was 50 μm or less. The amount of coke contained in the pseudo particles of 1 mm or less was measured for the pseudo particles after pulverization by the above method. The results are shown in Table 3.
The obtained pseudo particles were sintered in a 50 kg scale pan test to obtain sintered ore. The test conditions were as follows: the sintering pot had a diameter of 300 mm, a height of 600 mm, a layer thickness of 550 mm, and a suction negative pressure of 9.8 kPa (constant). The productivity of the obtained sintered ore was measured. These results are summarized in Table 3.

[Example 2]
Powder coke having a particle size distribution shown in Table 1 is sieved with a 0.25 mm sieve, and 10000 parts under the sieve, and as a hydrophobic substance in the present invention, VALFLON spray (manufactured by Inai Co., Ltd., active ingredient polytetrafluoroethylene) ) (Coke modifier 2) 200 parts were sprayed and stirred with a mixer for 10 minutes. The treated coke was re-mixed with the top portion of the sieve at the same mass ratio as before sieving (the coke obtained by re-mixing the treated coke is referred to as treated coke 2). That is, the 0.25 mm under sieve in Table 1 was replaced with the same mass of treated coke.
Sintered raw materials (raw materials for iron making) having the composition shown in Table 2 were prepared. Here, the treated coke 2 was used as the powder coke.
In the same manner as in Example 1, the GI index and the coke amount and productivity contained in the pseudo particles of 1 mm or less were measured. The results are shown in Table 3.

[Example 3]
The powder coke having the particle size distribution shown in Table 1 is sieved with a 0.25 mm sieve, and 10000 parts under the sieve, and as a hydrophobic substance in the present invention, silicon oil (manufactured by Toshiba Silicone Co., TSF-433) (coke 200 parts of modifier 3) was added and stirred with a mixer for 10 minutes. The treated coke was remixed with the top portion of the sieve at the same mass ratio as before sieving (the coke obtained by remixing the treated coke is referred to as treated coke 3). That is, the 0.25 mm under sieve in Table 1 was replaced with the same mass of treated coke.
Sintered raw materials (raw materials for iron making) having the composition shown in Table 2 were prepared. Here, the treated coke 3 was used as the powder coke.
In the same manner as in Example 1, the GI index and the coke amount and productivity contained in the pseudo particles of 1 mm or less were measured. The results are shown in Table 3.

[Example 4]
By the method described in WO 02/066688, a sodium acrylate / methyl acrylate copolymer having a weight average molecular weight of 33000 (composition ratio of sodium acrylate is 78.7 mol%, copolymer 1) is obtained. It was.
On the other hand, 10000 parts of powder coke having the particle size distribution shown in Table 1 and 400 parts of mixed vegetable oil B standard (made by Haruo Co., Ltd.), which is a recycled oil and fat as a hydrophobic substance, are added and mixed for 10 minutes with a mixer. 4 was obtained.
In Example 1, 5250 parts of the aqueous copolymer 1 solution previously adjusted to a non-volatile content of 0.27% was replaced with 5250 parts of an aqueous sodium polyacrylate solution having a weight average molecular weight of 6000 previously adjusted to a non-volatile content of 0.4%. The coke amount contained in the quasi-particles having a GI index of 1 mm or less and the production rate were evaluated in the same manner as in Example 1 except that the treated coke 4 was used instead of the treated coke 1. The results are shown in Table 3. The addition amount of the copolymer with respect to the sintering raw material was 0.02%.

[Example 5]
In the manufacturing method of the processing coke 1 described in Example 1, the processing coke is used except that 100 parts of plant mixed oil B standard (manufactured by Haruo), which is a recycled oil, is used instead of 200 parts of liquid paraffin as a hydrophobic substance. The processing coke 5 was obtained by the same method as the manufacturing method 1. Sintering raw materials (iron-making raw materials) having the compositions shown in Table 2 were prepared. Here, the treated coke 5 was used as the powder coke.
In Example 1, 5250 parts of the aqueous copolymer 1 solution previously adjusted to a non-volatile content of 0.27% was replaced with 5250 parts of an aqueous sodium polyacrylate solution having a weight average molecular weight of 6000 previously adjusted to a non-volatile content of 0.4%. The coke amount contained in the pseudo particles having a GI index of 1 mm or less and the production rate were evaluated in the same manner as in Example 1 except that the treated coke 5 was used instead of the treated coke 1. The results are shown in Table 3. The addition amount of the copolymer with respect to the sintering raw material was 0.02%.

[Comparative Example 1]
Sintered raw materials (raw materials for iron making) having the composition shown in Table 2 were prepared. Here, the powder coke used was not sieved.
In the same manner as in Example 1, the GI index and the coke amount and productivity contained in the pseudo particles of 1 mm or less were measured. The results are shown in Table 3.

[Comparative Example 2]
Sintered raw materials (raw materials for iron making) having the composition shown in Table 2 were prepared. Here, the powder coke used was not sieved.
70000 parts of the sintered raw material and 840 parts of quicklime were put into a drum mixer, and 5600 parts of water was sprayed (added) to the composition (sintered raw material) using a spray bottle over about 1.5 minutes. After spraying, the above-mentioned composition to which the dispersant was added (final composition for granulation treatment) was further stirred at the same rotational speed for 3 minutes to perform granulation treatment (pseudo granulation). In the same manner as in Example 1, the GI index and the coke amount and productivity contained in the pseudo particles of 1 mm or less were measured. The results are shown in Table 3.

[Comparative Example 3]
In Comparative Example 1, in place of 5250 parts of a sodium polyacrylate aqueous solution having a weight average molecular weight of 6000 adjusted to 0.4% nonvolatile content in advance, a β-naphthalenesulfonic acid formalin condensate previously adjusted to 14.7% nonvolatile content was used. The productivity of sintered ore was measured in the same manner as in Example 1 except that 5250 parts of an aqueous solution of a certain mighty 150 (trade name: manufactured by Kao Corporation) was used. The amount of β-naphthalenesulfonic acid formalin condensate added to the sintering raw material was 1.1%. Firing was impossible due to poor ignition of the sintered raw material.

[Example 6]
In Example 1, in place of 5250 parts of an aqueous sodium polyacrylate solution having a weight average molecular weight of 6000 adjusted to 0.4% nonvolatile content in advance, a β-naphthalenesulfonic acid formalin condensate previously adjusted to 14.7% nonvolatile content was used. The productivity of sintered ore was measured in the same manner as in Example 1 except that 5250 parts of an aqueous solution of a certain mighty 150 (trade name: manufactured by Kao Corporation) was used. The amount of β-naphthalenesulfonic acid formalin condensate added to the sintering raw material was 1.1%. The results are shown in Table 3.

In Table 3, “Note” indicates that the fire was extinguished immediately after ignition and firing was not possible.

Claims (5)

A method of granulating a sintered raw material for iron making containing fine iron ore in the presence of a fuel that essentially requires coke and / or anthracite coal,
The method for granulating the sintered raw material for iron making is preliminarily made from a compound having a paraffin chain having 5 or more carbon atoms, a compound having a naphthene ring, a silicone and a fluorine-containing compound in part or all of coke and / or anthracite. After adding and stirring one or more hydrophobic substances selected from the group consisting of, added to a sintered raw material for iron making containing fine iron ore, selected from the group consisting of carboxyl groups, sulfonic acid groups and salts thereof It is a method of granulating in the presence of a polymer compound having at least one group,
The compound having a paraffin chain having 5 or more carbon atoms and the compound having a naphthene ring have a flash point of 65 ° C. or higher,
The polymer compound is a polymer compound obtained by polymerizing a monomer composition mainly composed of (meth) acrylic acid and / or a salt thereof, and / or a β-naphthalenesulfonate formalin condensate. <br/> A method for granulating a sintered raw material for iron making. The method for granulating a sintered raw material for iron making according to claim 1, wherein the addition amount of the hydrophobic substance is 0.05 to 10% by mass with respect to 100% by mass of coke and / or anthracite. The said high molecular compound is polymerized by the monomer composition containing 10 mol% or more of (meth) acrylic acid and / or its salt , The sintering raw material for iron manufacture of Claim 1 or 2 characterized by the above-mentioned. Granulation treatment method. The polymer compound is obtained by an aqueous solution polymerization method.
The granulation processing method of the sintering raw material for iron manufacture in any one of Claims 1-3 characterized by the above-mentioned. The polymer compound has a weight average molecular weight of 1,000 to 100,000.
The granulation processing method of the sintering raw material for iron manufacture in any one of Claims 1-4 characterized by the above-mentioned.