BR112012003768B1 - COLD CONNECTED CARBON COMPOSITES FOR HIGH OVEN AND THE METHOD FOR THEIR MANUFACTURE - Google Patents

Description

(54) Title: COLD CONNECTED CARBON COMPOUNDS FOR HIGH OVENS AND THE METHOD FOR THEIR MANUFACTURE (51) Int.CI .: C22B 1/243; C21B 5/00 (30) Unionist Priority: 21/08/2009 JP 2009-192273 (73) Holder (s): NIPPON STEEL & SUMITOMO METAL CORPORATION (72) Inventor (s): HIROKAZU YOKOYAMA; KAZUYA KUNITOMO; KENICHI HIGUCHI

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Invention Patent Descriptive Report for

COLD-CONNECTED CARBON COMPOUNDS COLD FOR HIGH OVENS AND THE METHOD FOR THEIR MANUFACTURE.

Technical Field [001] The present invention relates to agglomerates containing unburned carbon (cold bonded carbon composite agglomerates) for blast furnaces, which are produced by mixing and molding unprocessed carbon-containing raw materials and unprocessed iron-containing raw materials and then healing a molded body. Particularly the present invention relates to cold - bonded carbon composite agglomerates (iron ore agglomerates) having a carbon content (TC) in a range of 18 to 25% by weight and a porosity in a range of 20 to 30 %.

[002] The present patent application claims priority over Japanese patent application 2009-192273, filed on August 21, 2009, the content of which is incorporated herein by reference. Background of the Technique [003] Conventionally, various types of powders containing iron and powders containing carbon that are collected from various dust collectors in iron works are combined, a cement-based hydraulic binder is added, and the mixture is kneaded and shaped to manufacture of cold-bonded pellets and briquettes having diameters in a range of 8 to 16 mm that are used as unprocessed raw materials for a blast furnace.

[004] As a method for making cold-bonded carbon composite agglomerates, a process is known in which iron-making powder is granulated into pellets and the pellets are then cured and hardened. In the process in which iron-making powder is granulated into pellets, the size distribution of

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2/38 particle of the powder is adjusted within an appropriate range, then a binder such as quenched lime, cement, or the like and 5 to 15% water is added, and the mixture is granulated by a pelletizer or similar to obtain the pellets.

[005] In the method of manufacturing such cold-bonded carbon composite agglomerates, an increase in carbon content (TC) in cold-bonded carbon composite agglomerates was required for the purpose of reducing the rate of reducing agent in an operation blast furnace.

[006] For example, according to Patent Document 1, an unprocessed raw material containing iron oxide and a carbon-based carbon material (carbonaceous material) are combined, a binder is added, and the mixture is kneaded, molded, and cured to manufacture cold-bonded carbon composite agglomerates. Cold-bonded composite carbon agglomerates contain carbon, and the carbon content is 80 to 120% of the theoretical amount of carbon required to reduce iron oxide included in the unprocessed raw material containing iron oxide to obtain metallic iron. In addition, the binder is selected so that the resistance to crushing at normal pressure becomes 7850 kN / m ² or more, and then kneading, molding, and curing are performed. Since the reduction reaction occurs due to carbon mixed with iron oxide within cold-bonded carbon composite agglomerates, it is possible to improve the reduction rate.

[007] However, with regard to the cold-bonded carbon composite agglomerates of Document 1, the carbon content is limited to insure resistance, and it is not possible to obtain a sufficient rate-reducing effect in the blast furnace. In the case where a large amount of these cold-bonded carbon composite agglomerates are used in the blast furnace to obtain

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3/38 sufficiently the effect so that the rate of reducing agent is reduced, a quantity of heat absorption due to a dehydration reaction of the binder in the blast furnace becomes large. Therefore, a low temperature thermal reserve zone is formed. There is a disadvantage in that the disintegration of sintered ores (iron ore sintered) during reduction is facilitated by the low temperature thermal reserve zone.

[008] In Patent Document 2, attention is paid to the fact that particle sizes and carbon contents of carbon materials (carbonaceous materials) greatly affect hot resistance in an area of temperature reduction as well as cold resistance of composite pellets of cold-bonded carbon. [009] From the point of view, Document Document 2 proposes a process for the manufacture of cold-bonded carbon composite agglomerates for blast furnaces having a cold crushing resistance of 50 kg / cm ² or more. This manufacturing process includes: adding a hydraulic binder to fine spray of material containing iron that contains 40% by weight or more of iron and fine spray of carbon material (carbonaceous material) that contains 10% by weight or more of carbon; mixing the mixture while a water content is adjusted, and granulating. In the manufacturing process, the particle sizes of all unprocessed raw materials are set to 2 mm or less, the combination ratio of the fine powder of carbon material (carbonaceous material) is adjusted so that the carbon ratio contained (TC) in all unprocessed raw materials become in a range of 15 to 25% by mass, and the average size of the fine powder of carbon material (carbonaceous material) is set to be in a range of 100 to 150 micrometers.

[0010] As described above, with respect to agglomerates

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4/38 cold-bonded carbon composites for blast furnaces, improved carbon content, improved reduction rate, and improved cold strength and hot strength (which affect a degree of disintegration in the furnace) have been issues. In addition, cold-bonded agglomerates for blast furnaces require an appropriate water content in granulation and molding processes. In addition, since the strength of the cement-based binder is developed by a hydration reaction, the amount of combined water (crystallization water) is greater than that of the other unprocessed raw materials, and therefore, there is a disadvantage where a blast furnace break property is poor. [0011] On the other hand, converter dust generated in iron works is collected by a non-combustion gas processing apparatus and the converter powder as raw raw materials of iron is mixed with pulverized carbon, and pellets are produced. The pellets are partially reduced in reduced iron in a reduction furnace with a rotary threshold and are reused. The converter powder to be collected contains a large amount of water and has poor handling properties and poor mixing properties with other powders. Therefore, the converter powder is dried and then used. However, metallic iron having a large specific surface area is contained in a fine powdered state in the converter powder, and there is a problem in which the metallic iron reacts with air and generates heat due to oxidation in the case where the converter powder is excessively dried.

[0012] Patent Document 3 shows a process for recycling converter powder. The process includes: mixture of powder containing iron oxide and powder containing carbon in the converter powder that is collected by a non-combustion conversion gas dust collector; adjusting a water content of the mixture

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5/38 for 17 to 27% by weight; mixing molding to produce a molded body having a porosity of 40 to 54%; and reduction of the molded body through a reduction furnace with a rotary threshold. According to this process, heat generation due to oxidation of metallic iron is prevented, and a satisfactory rate of reduction can also be obtained.

[0013] According to this process, there is an effect of preventing heat generation due to oxidation when the molded body is reduced in the reduction furnace with a rotary threshold. Therefore, this process does not directly assist the improvement of the bursting property in a blast furnace that has different operating conditions such as operating temperature and the like. [0014] In addition, Document Patent 4 shows a process for reducing iron oxide through the use of a reduction furnace with a rotary threshold. This process includes: placing a molded body containing metal oxide and carbon on a moving sill; and heating of the molded body through the combustion gas heat of an upper part to effect reduction of burning. In the process, a porosity of the molded body containing ferric oxide is adjusted to a specific value. By adjusting the porosity of the molded body to the specific value, volume expansion generated by reducing the iron oxide from hematite to magnetite is absorbed by air holes. Therefore, stable reduction with less disintegration can be achieved.

[0015] This method is also effective for preventing disintegration during the reduction of the molded body in the reduction furnace with a rotary threshold. However, this process does not directly assist in preventing disintegration in a blast furnace that has different operating conditions such as operating temperature, reduction pattern, and the like.

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6/38 [0016] In order to improve disintegration resistance with respect to overflow due to water vapor, disintegration during reduction (disintegration due to reduction, reduction disintegration), and the like, an iron oxide reduction capacity in the agglomerates cold-bonded carbon composites, cold-shredded resistance, and hot-shredded resistance in order to provide cold-bonded carbon composite agglomerates for blast furnaces capable of performing efficient blast furnace operations, it is necessary to maintain the carbon content in the composite agglomerates carbon to blast furnaces at a constant level and fix a structural morphology in detail for porosity.

[0017] However, if the porosity is high, gasification of the carbonaceous materials and the rate of reduction of the iron oxide are promoted while the cold resistance and hot resistance are degraded. In addition, if the porosity is excessively low, there is a problem in which the disintegration in the oven such as overflow due to water vapor, disintegration during reduction, and the like becomes more noticeable.

Prior Art Document

Patent Document

Patent Document 1: Japanese unexamined patent application, first publication N ^o. 2003-342646

Patent Document 2: Japanese unexamined patent application, first publication N ^o. 2008-95177

Patent Document 3: Patent Application Unexamined Japanese, first publication ^No.. 2003-82418

Patent Document 4: Japanese unexamined patent application, first publication N ^o. 2003-89813 Exhibition of the Invention

Problems to be solved by the invention

Petition 870170093591, of 12/01/2017, p. 9/46

The object of the present invention is to specify the porosity and carbon content of carbon composite agglomerates that are suitable for efficient blast furnace operations; and therefore, the present invention aims to provide cold-bonded carbon composite agglomerates for blast furnaces that make it possible to carry out efficient blast furnace operations, and a process for their manufacture.

Means for solving problems [0019] The present inventors have examined a porosity and a carbon content of carbon composite agglomerates for blast furnaces. As a result, the present inventors have found that it is possible to provide cold-bonded carbon composite agglomerates capable of obtaining the following properties by controlling combination conditions and production conditions so that the porosity becomes in a range of 20 to 30% and the carbon content becomes in a range of 18 to 25% by mass in the cold-bonded composite carbon agglomerates.

(a) Excellent disintegration resistance with respect to bursting due to water vapor and disintegration during reduction (disintegration due to reduction, reduction disintegration) (b) High iron oxide reduction capacity in cold-bonded carbon composite agglomerates ( c) Promotion of reduction for peripheral iron ores (loaded iron-based substance) [0020] The combination conditions to be controlled are particle sizes (particle size distributions) of unprocessed raw materials, an amount of fine powder carbon, a combination amount of ores having a high content of combined water, an amount of cement, and the like. [0021] Cold-bonded carbon composite clusters for

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8/38 blast furnaces according to one embodiment is manufactured by mixing and kneading unprocessed raw materials containing iron, unprocessed raw materials containing carbon, and a binder, molding a kneaded substance to obtain a molded body, and then curing the molded body, where a carbon content (TC) is in a range of 18 to 25% by weight, and a porosity is in a range of 20 to 30%.

[0022] A method for manufacturing cold-bonded carbon composite agglomerates for blast furnaces in accordance with an embodiment of the present invention includes: forming a molded body by mixing and kneading unprocessed raw materials containing iron, raw materials raw materials containing carbon, and a binder and shaping a kneaded substance to obtain a shaped body; and obtaining cold-bonded carbon composite agglomerates through and subsequently curing the molded body, where in the formation of the molded body, one or more combination conditions selected from the group consisting of a water content in the raw materials, a particle size of the unprocessed raw materials, an amount of fine coke, an amount of ore combination having a high combined water content, and an amount of binder combination are adjusted so that a carbon content (TC) is in a range of 18 to 25% by mass and a porosity is in a range of 20 to 30% in the cold-bonded composite carbon agglomerates.

Effects of the Invention [0023] Cold-bonded carbon composite agglomerates for blast furnaces in accordance with an embodiment of the present invention Have sufficient carbon content to improve not only a rate of reduction of cold-bonded carbon composite agglomerates, but reduction rates for major raw materials are not

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9/38 processed products containing iron for blast furnaces such as sintered ores (sintered iron ore) and the like. In addition, the cold shredding strength of 100 kg / cm ² or more that is required for unprocessed raw materials for blast furnaces is maintained, and hot strength in a reduction temperature region is higher than that of iron ore pellets. conventional. [0024] Therefore, it is possible to suppress disintegration of the cold-bonded carbon composite agglomerates such as bursting due to water vapor, disintegration during reduction, and the like in blast furnace operations. In addition, it is possible to greatly reduce the rate of reducing agent (coke ratio) during blast furnace operations. As a result, efficient blast furnace operations can be carried out.

[0025] Since a non-sintering process (without burning) is applied to the process for manufacturing cold-bonded carbon composite agglomerates for blast furnaces in accordance with an embodiment of the present invention, it is possible to save energy and reduce CO2 as compared to a sintering (burning) process. In addition, it is possible to recycle powders generated in the ironmaking process as raw materials containing iron and carbon materials (carbonaceous materials) through a relatively simple and inexpensive process.

Brief Description of the Drawings [0026] Figure 1 is a diagram showing relationships between degrees of porosity and disintegration during reduction of cold-bonded carbon composite agglomerates.

[0027] Figure 2 is a diagram showing relationships between porosities and bursting properties of cold-bonded carbon composite agglomerates.

[0028] Figure 3 is a diagram showing a relationship between a

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10/38 degree of disintegration during reduction and a higher K value of cold-bonded carbon composite agglomerates.

[0029] Figure 4 is a diagram showing relationships between carbon content (T.C) and breaking properties of cold-bonded carbon composite agglomerates.

[0030] Figure 5 is a diagram showing a relationship between a burst property and a higher K value of cold-bonded carbon composite agglomerates.

[0031] Figure 6 is a diagram showing relationships between porosities and cold crushing resistances of cold-bonded carbon composite agglomerates with different carbon contents.

[0032] Figure 7 is a diagram showing relationships between porosities and rates of reducing agent in a BIS oven of cold-bonded carbon composite agglomerates with different carbon contents.

[0033] Figure 8 is a diagram showing relationships between porosities and the reduction rates at 1000 ° C of agglomerated cold-bonded carbon composites with different carbon contents.

Best Mode for Carrying Out the Invention [0034] The cold-bonded carbon composite agglomerates for blast furnaces of the present embodiment are produced through a process in which raw materials containing iron, raw materials containing carbon, and a binder they are mixed and kneaded, a kneaded substance is molded to obtain a molded body, and the molded body is then cured. The carbon content (T.C. is in a range of 18 to 25% by weight, and the porosity is in a range of 20 to 30%. Therefore, it is possible to suppress disintegration of the composite carbon agglomerates

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11/38 cold bonded such as bursting due to water vapor, disintegration during reduction, and the like in blast furnace operations and the rate of reducing agent in a blast furnace can also be reduced.

[0035] In this embodiment, the carbon content (T.C) of the cold-bonded carbon composite agglomerates is fixed to be in a range of 18 to 25% by mass.

[0036] As will be described later in Examples, in the case where the carbon content (TC) exceeds 25% by mass, it is not possible to maintain the minimum cold grinding resistance that is necessary for use in a blast furnace (figure 6) . In addition, a bursting property becomes remarkable, and it is impossible to perform stable operations in a real blast furnace (figures 4 and 5).

[0037] In the case where the carbon content (T.C) is less than 18% by mass, a reduction rate improvement effect becomes small (figures 7 and 8). That is why it is not possible to obtain the effect of improving blast furnace operations.

[0038] The carbon content (T.C) of cold-bonded carbon composite agglomerates is preferably in a range of 20 to 23% by weight, and more preferably in a range of 22 to 23% by weight.

[0039] In this realization, the porosity of the cold-bonded carbon composite agglomerates is fixed to be in a range of 20 to 30%.

[0040] As will be described later in the Examples, in the case where the porosity is less than 20%, the reduction rate improvement effect is limited (figures 7 and 8). In addition, the degree of disintegration in the blast furnace is increased and there may be cases where the degree of disintegration exceeds the upper limit required for unprocessed raw materials used in the blast furnace (figure 1).

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12/38 [0041] In the case where the porosity exceeds 30%, the reduction rate improvement effect is saturated (figures 7 and 8). In addition, the cold crush resistance is decreased, and it becomes impossible to maintain the minimum cold crush resistance that is required for use in the blast furnace (figure 6).

[0042] The porosity of cold-bonded carbon composite agglomerates is preferably in a range of 23 to 27%, and more preferably in a range of 24 to 26%.

[0043] The method for manufacturing cold-bonded carbon composite agglomerates for blast furnaces according to the present embodiment includes: a step of forming a molded body in which raw materials containing iron, raw materials containing carbon, and a binder are mixed and kneaded, and a kneaded substance is molded to obtain the molded body, and a subsequent molded body curing step. In forming the molded body, one or more combination conditions selected from a group consisting of a water content in the unprocessed raw materials, a particle size of the unprocessed raw materials, an amount of fine coke (fine powdered coke) , a combination amount of ores having a high combined water content, and a combination amount of binder are adjusted so that the carbon content (TC) is in a range of 18 to 25% by weight and the porosity it is in a range of 20 to 30% in cold-bonded carbon composite agglomerates.

[0044] As the raw materials containing iron used in this realization, a sintering powder generated in the ironmaking process, a powder containing iron such as a burnt powder obtained by sludge containing burning oil, fine iron ores such as a feed pellet or the like having sizes of

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13/38 particles smaller than those of powdered iron ore for sintering, ores having a high content of combined water that contain a large amount of combined water (water of crystallization), and the like are exemplified.

[0045] As the raw materials containing carbon used in the making, a primary blast furnace powder, a coke powder, fine coke, anthracite, are exemplified.

[0046] In the realization, water content in unprocessed raw materials is also referred to as free water and means a water content included in unprocessed raw materials in a raw molded body after molding (before curing). By increasing the water content of unprocessed raw materials, it is possible to increase porosity. However, if the water content in unprocessed raw materials is excessively high, the degree of disintegration (bursting property) becomes greater. For this reason, it is preferable to adjust the water content of raw materials within a range of 8 to 15%.

[0047] In the realization, the particle size of the unprocessed raw materials means a heavy average value of d50 mass median sizes of the raw materials containing iron and the raw materials containing carbon to be used. By reducing the particle size of unprocessed raw materials, it is possible to decrease porosity. However, in the case where the size of unprocessed raw material particles is excessively small, the degree of disintegration (bursting property) becomes greater, and problems such as adhesion at the time of production and the like occur. For this reason, it is preferable to adjust the weighted average value of the median mass sizes d50 within a range of 10 to 50 micrometers.

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14/38 [0048] In the realization, fine coke means fine powdered coke having a median d50 size of 100 micrometers or less. By increasing the quantity of fine coke as raw raw materials containing carbon, it is possible to increase porosity. However, if the amount of fine coke is excessively small, there is a problem in which the degree of disintegration (bursting property) becomes greater. Therefore, it is preferable to adjust the amount of fine coke within a range of 10 to 30%.

[0049] In the realization, ores having a high content of combined water means ores that contain 5% or more of combined water (water of crystallization) such as Robe River, Yandicoogina, Marra Mamba, or the like. By increasing the quantity of ores having a high combined water content, it is possible to increase the porosity of the cold-bonded carbon composite agglomerates. However, if the quantity of ores having a high combined water content is excessively large, the degree of disintegration (bursting property) becomes greater. Therefore, it is preferable to adjust the amount of ore combination having a high combined water content within a range of 5 to 20%.

[0050] As the binder used in the making, an aging binder including fine powder containing granulated blast furnace slag as a main constituent and an alkaline stimulant, which is generically used, quenched lime, Portland cement, bentonite, and the like are exemplified. The amount of combination (amount of additive) of the binder can be appropriately determined taking into account other and similar conditions of combination. In the case where the amount of combination of the binder is excessively small, it is difficult to maintain

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15/38 sufficiently cold rolling resistance of cold-bonded carbon composite agglomerates. In addition, in the case where the amount of combination of the binder is excessively large, the amount of slag in the cold-bonded carbon composite agglomerates is increased, and the air permeability of the furnace part becomes unstable. Therefore, it is not possible to stably have a reducing agent rate reduction effect. From the above views, a particularly preferable range of the amount of binder combination is in a range of 5 to 19% by mass.

[0051] In the molding stage, unprocessed raw materials containing iron and unprocessed raw materials containing carbon cut from an unprocessed raw material hopper are loaded and mixed with a binder such as cement or the like in a wet ball mill, a Lodige mixer, or the like. Then, water is added, and then the mixture is kneaded. The kneaded substance of the unprocessed raw materials obtained after sufficient kneading is molded by a Pan pelletizer, a briquette machine, or the like. Then, in the molded body curing stage, the molded body is cured in the sun for several days until the necessary handling strength appears on a primary curing ground. Then, the molded body is cured in the sun on a secondary curing ground to allow sufficient resistance due to the binder such as cement or the like to arise. Therefore, cold-bonded carbon composite agglomerates for blast furnaces are produced. Then, cold-blown carbon composite pellets for blast furnace are supplied to, and used in the blast furnace. [0052] In the present embodiment, it is possible to fix the carbon content (T.C) to be in a range of 18 to 25% by mass and to fix the porosity to be in a range of 20 to 30% of the agglomerates

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16/38 cold-bonded carbon composites by adjusting production processes (pellets, briquettes) and combining conditions (a water content in unprocessed raw materials, a particle size of unprocessed raw materials, an amount of fine coke, a combination amount of ores having a high combined water content, and a combination amount of binder). In particular, it is possible to do so by adjusting one or more combination conditions selected from the group consisting of a water content in unprocessed raw materials, a particle size of unprocessed raw materials, an amount of fine cokes, a combination amount of ores having a high combined water content, and combination amount of binder.

[0053] Although a body molded in pellet is more porous than a body molded in briquette, any one of them can be selected depending on the conditions of unprocessed raw materials.

[0054] As described above, the greater the amount of cement combination (amount of binder combination) is, the finer the cold-bonded carbon composite agglomerates become. If one of the water content in unprocessed raw materials, the amount of fine carbon powder (amount of fine coke), or the amount of ore combination having a high content of combined water increases, the porosity increases. However, it is preferable to adjust them in consideration of molding performance, adhesion at the time of production, and product constituents.

[0055] Although carbon in the cold bonded carbon composite agglomerates of the present embodiment reduces iron oxide in the cold bonded carbon composite agglomerates, excess

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17/38 carbon still reduces iron ores in the periphery in the blast furnace. In the same way, it is possible to improve the reduction rate (figures 7 and

8).

[0056] In sequential blast furnace operations, CO (reducing gas) reduces iron ores while rising from a lower layer to an upper layer in the blast furnace. However, in the case where the blast furnace was operated only with the use of coke as a reducing material, the reducing gas reduction force is weakened in the upper layer of the ore layers, and there have been cases where ore reduction does not proceed enough.

[0057] On the other hand, when the cold-bonded carbon composite agglomerates of the present embodiment are used, it is possible to greatly improve the reduction efficiency particularly in the upper layer of the ore layers due to the presence of the cold-bonded carbon composite agglomerates of the present realization together with iron ores in the blast furnace. Since it is possible to greatly improve the reduction efficiency in the upper layer of the ore layers in which the reduction is difficult to proceed, the reduction efficiency of the entire blast furnace is greatly improved. Therefore, it is possible to reduce a greater amount of reduction materials than the amount of cokes which is the same as the excess amount of carbon in the cold-bonded carbon composite agglomerates of the present embodiment (figure 7). [0058] In addition, since the reduction efficiency of the entire blast furnace can be greatly improved, it is possible to reduce the rate of reducing agent in relation to blast furnace operations, which also includes pulverized coal injected through a nozzle. Since the rate of reducing agent can be reduced, it is also possible to reduce the amount of CO ₂ generated in the process of

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18/38 ironmaking and therefore to reduce environmental load.

Examples [0059] Hereinafter, descriptions of embodiments of the present invention based on specific Examples will be given. These are only embodiments, and the present invention is not limited to them.

(Example 1) (Production of cold-bonded composite carbon agglomerates) [0060] Raw materials containing iron, raw materials containing carbon, and a binder were used, and mixing, water addition, kneading, molding (granulation ) were performed while adjusting the combination quantities of unprocessed raw materials, a particle size, and a water content as shown in Table 1 to produce cold bonded carbon composite agglomerates.

[0061] With respect to the cold-bonded carbon composite agglomerates obtained, porosities were measured using a water process (based on JIS K2151) in which water displacement was performed to measure an apparent specific weight.

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Table 1

Inventive Example 1 Inventive Example 2 Inventive Example 3 Example Comparative Unprocessed raw materials containing iron (% by mass) 75 63 71 65 Details Sintering powder (% by mass) 55 40 35 30 Fine iron ores (% by mass) 10 5 30 10 Ores having a high content of combined water (% in 10 18 6 25 pasta) Ore brand having high combined water content Robe River Yandi-coogina Marra Mamba Robe River Unprocessed raw materials containing carbon (% by mass) 15 29 11 31 Details Primary blast furnace powder (% by mass) 0 1 0 12 Coke powder (% by mass) 1 0 0 8 Fine coke (% by mass) 12 27 11 8 Anthracite (mass%) 2 1 0 3 Binder (% by mass) 10 8 18 4 Details Granulated blast furnace slag 2 0 4 0 Portland cement 8 7 12 4 Bentonite 0 1 2 0 Total amount of combined raw materials (% by mass) 100 100 100 100 Water content in raw materials (% by mass) 12 14 9 16 Particle size of unprocessed raw materials, d50 (pm) 20 35 12 55 Carbon content composite agglomerates (% by mass) 20 24 19 26 cold-bonded carbon Porosity (%) 25 29 21 31

19/38

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20/38 [0062] Table 1 shows specific types of raw iron-containing raw materials, types of raw carbon-containing raw materials, water content in unprocessed raw materials, particle sizes of unprocessed raw materials (average values), the types of the combination quantities of ores including combined water (crystallization water), the types and combination quantities of the binders, the carbon contents and the porosities of the cold-bonded carbon composite agglomerates.

[0063] It was verified that the cold-bonded carbon composite agglomerates of the realization can be produced by adjusting the water content in unprocessed raw materials, the particle size of unprocessed raw materials, the amount of combination of ores having a high combined water content, and the amount of binder within the range shown in Table 1.

[0064] Here, it is not necessary to limit the granulation equipment, and any granulation equipment with functions for kneading unprocessed raw materials, adding water, granulating and sieving a molded body is applicable and a kneading machine, a granulator, and the like are not particularly limited.

(Example 2) (Influence of Porosity) [0065] Cold-bonded composite carbon agglomerates having different porosities were prepared to examine the influence of porosity on a phenomenon of disintegration of cold-bonded carbon composite agglomerates in the kiln.

[0066] The raw materials containing iron and the raw materials containing carbon which were the same as those in Example 1 were fractured and mixed

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21/38 with cement (binder). The mixture was kneaded, and a kneaded substance was molded. The molded body obtained was cured for a predetermined period to produce cold bonded carbon composite agglomerates having a carbon content (T.C) of 15% by mass or 25% by mass.

[0067] Here, the combination quantities of the raw materials containing iron and the raw materials containing carbon have been set to constant values, and the molding pressure for compression molding and the amount of cement have been adjusted to produce carbon composite agglomerates. cold bonded having a porosity of 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%. In addition, by fine-tuning the brand of unprocessed raw materials containing carbon according to the change in the amount of cement combination, the carbon content was made constant at 15% by mass or 25% by mass.

[0068] A disintegration property (disintegration property during reduction) has been assessed through the following process in which a test for disintegration during reduction (JIS M8720) has been applied. The temperature of a 500 g sample was raised to N2 and maintained at 550 ° C in reducing gas containing 30% CO for a predetermined period. At this time, a reduction time at 550 ° C was set to 1 minute, 10 minutes, 30 minutes, or 60 minutes; and for that, samples for measurement were produced. Then, 900 rotation speed impact was applied to the sample for measurement on a speed test machine. The ratio of particles having sizes of 2.8 mm or less in the sample for measurement after application of rotation impact (degree of disintegration (-2.8 mm%)) was measured, and the property of disintegration during reduction was assessed based on degree of disintegration (-2.8 mm%). The results for cold-bonded carbon composite pellets

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22/38 having a carbon content (TC) of 25% by mass are shown in Table 2 and figure 1. Here, the degree of disintegration (-2.8 mm%) measured by applying a test for disintegration during reduction also will be referred to as the degree of disintegration during reduction in this specification.

Table 2

Disintegration property during reduction (degree of disintegration during reduction); Degree of Disintegration (-2.8 mm%) Porosity (%) Reduction Time (minutes) 1 minute 10 minutes 30 minutes 60 minutes 5.1% 10 20 40 80 10% 7.5 15 30 60 15.6% 6.25 12.5 25 50 20.2% 5 10 20 40 24.8% 4.75 9.5 19 38 30% 4.5 9 18 36 33.9% 4 8 16 32 39.4% 3.75 7.5 15 30

[0069] In addition, the burst property in the blast furnace, which is the biggest weakness of cold-bonded agglomerates, has also been assessed.

[0070] The burst property was measured using the following process with reference to an iron ore crackle test process (ISO 8371): Iron ore - Determination of description index). 500 g of a sample was quickly heated to a maximum temperature of 700 ° C in N ₂ . At this time, in order to examine the influence of heating speed (temperature rise speed), the heating speed was fixed at 5 ° C / minute, 50 ° C / minute, 500 ° C /

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23/38 minutes, or 1000 ° C / minute; and for that, samples for measurement were produced. Then, the ratio of particles having sizes of 6.3 mm or less in the sample for measurement (degree of disintegration (-6.3 mm%)) was measured, and the degree of disintegration was assessed as the burst property. The results for the cold-bonded carbon composite agglomerates having a carbon content (T.C) of 15% by mass are shown in Table 3 figure 2.

Table 3

Breaking property; Degree of disintegration (-6.3 mm%) Porosity and (%) Speed c l temperature rise (° C / minute) 5 ° C / minute 50 ° C / minute 500 ° C / min O 1000 ° C / min O 5.1% 10 20 40 80 10% 10 20 40 80 15.6% 8.75 17.5 35 70 20.2% 7.5 15 30 60 24.8% 6,875 13.75 27.5 55 30% 6.25 12.5 25 50 33.9% 5.625 11.25 22.5 45 39.4% 5 10 20 40

[0071] In general, a disintegration phenomenon caused by gas generation due to evaporation and gasification of contained water and combined water (water of crystallization) (derived from iron ore and cement) is called bursting. In addition, a disintegration phenomenon caused by slack generation, volume expansion, and internal stress that occurs in connection with the reduction is called disintegration during reduction. In this specification, the inventors aim to define conditions by considering the degree of disintegration in the furnace, regardless of the causes of the phenomena; and so disintegration can be used for both

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24/38 in some cases in the description that follows.

[0072] Referring to figure 1, it can be understood that the reduction time has a great influence while the degree of disintegration is intended to be decreased when the porosity is increased. Disintegration during reduction is caused by volume expansion and internal tension at the time of reduction from hematite to magnetite, and the most active disintegration is observed at around 550 ° C. For this reason, it is known that disintegration during reduction depends on residence time at around 550 ° C. That is, in the reduction in temperatures of 550 ° C or more, the disintegration is actually reduced. Therefore, residence time at 550 ° C as well as porosity affect disintegration during reduction.

[0073] In the reduction furnace with a rotary hearth, the temperature rise speed is 1000 ° C / minute, which is high, and the residence time at 550 ° C is about 1 minute. Therefore, disintegration during reduction is small in scale. On the other hand, in the blast furnace, the residence time at 550 ° C is in a range of 10 minutes (central part) to 60 minutes (peripheral part); and therefore, there is a problem that the rate of disintegration during reduction becomes higher.

(Example 3) (Allowable range of degree of disintegration during reduction) [0074] In order to perform stable operations in a real blast furnace, it is necessary to set a higher K value being in the range of 0.4 or less in general. From the upper limit of the upper K value, a permissible range of the degree of disintegration during reduction of the cold-bonded carbon composite agglomerates was examined. [0075] The combination quantities of unprocessed raw materials have been adjusted so that the carbon content (T.C)

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25/38 became 25% by mass, and cold-bonded carbon composite agglomerates having different porosities were produced in the same manner as in Example 2.

[0076] The degrees of disintegration (-2.8 mm%) were measured in the same way as in the evaluation process for the disintegrating property during reduction in Example 2.

[0077] In addition, in order to assess air permeability of a shaft part during the use of the blast furnace, the upper K values were measured using the following process. In a blast furnace having an internal volume of 4500 m ³ , several types of cold-bonded carbon composite agglomerates having different porosities (for example, degrees of disintegration) were used to perform short-term tests. Cold-bonded composite carbon agglomerates at a content of 10% by weight of the total content of iron-based charged substances were mixed and loaded into an ore layer. According to operating specifications for the blast furnace under basic conditions, the rate of reducing agent was 480 kg / tp, and a weight ratio between ores and coke was 5.0. An air flow resistance value (upper K value) at the top of the shaft was calculated from a measurement value of a pressure probe installed on an oven wall. The results obtained are shown in Table 4 and figure 3.

Table 4

Porosity (%) Degree of disintegration during reduction (-2.8mm%) Higher K value (-) 5.1 22 0.3 10 39 0.39 15.6 50 0.45 20.2 55 0.51 24.8 58 0.52

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30 43 0.43 33.9 20 0.28 39.4 25 0.35

[0078] Figure 3 shows a relationship between the degree of disintegration and the upper K value of cold-bonded carbon composite agglomerates. As described above, in order to perform stable operations in the real blast furnace, it is necessary to set the upper K value to be in a range of 0.4 or less. From the relationship between the degree of disintegration (degree of disintegration during reduction) and the upper K value of the cold-bonded carbon composite agglomerates shown in figure 3, it can be understood that with respect to the cold-bonded carbon composite agglomerates having the carbon content of 25% by weight, the upper K value is raised to above 0.4 and it is difficult to carry out stable operations when the degree of disintegration (degree of disintegration during reduction) exceeds 40%. Therefore, it is important to decrease the degree of disintegration (degree of disintegration during reduction) to 40% or less for cold-bonded carbon composite agglomerates having a carbon content of 25% by weight.

[0079] Referring to figure 1, the degrees of disintegration are relatively low values in the case where the porosities are in a range of 20% or more. On the other hand, the degrees of disintegration are limited to 20% and suddenly increased when the porosities are in the range of 20% or more. This trend is particularly noticeable in the case where the reduction time is 30 minutes or more. On the other hand, in the case where the porosity is fixed to a range of 20% or more, it is possible to suppress the degree of disintegration (degree of disintegration during reduction) to 40% or less even in the case where the reduction time is 60 minutes. This is considered to be due to the internal stress caused by the expansion of

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27/38 volume of dry-bonded composite carbon agglomerates to be dispersed due to air holes when porosity is increased and therefore disintegration during reduction is considered to be suppressed. In the same way, in order to solve the problem of disintegration (disintegration during reduction) of cold-bonded carbon composite agglomerates for blast furnaces, it is necessary to fix the reduction time to be as short as possible and fix the porosity to be in a range of 20% or more.

[0080] Referring to figure 2, the disintegration (bursting property) tends to be reduced when the porosity is increased; however, the influence of the temperature rise speed is notable. This is considered to be because the amount of generation and the amount of water vapor discharge are not balanced within the sample for a time when the temperature rise speed is higher and the internal pressure is increased. In the reduction furnace with a rotary hearth, the temperature rise speed is 1000 ^o / minute which is high, and the dry-bonded carbon composite agglomerates explode easily. On the other hand, the speed of temperature rise in the blast furnace is in the range of 5 ° C / minute (part and peripheral) to 50 ° C (central part). Therefore, with reference to figure 2, it is possible to consider that the disintegration problem (bursting property) does not occur when cold-bonded carbon composite agglomerates having a carbon content of 15% by mass are used in the blast furnace.

(Example 4) (Influence of carbon content) [0081] Next, the influence of the carbon content | (T.C) of cold-bonded carbon composite agglomerates was examined. [0082] Cold-bonded carbon composite agglomerates having

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28/38 different carbon content (T.C) and porosity were prepared to examine the influence of carbon content (T.C) on disintegration (bursting property).

[0083] In the same way as in the process for Example 2 where the combination quantities of the raw materials containing iron and the raw materials containing carbon, molding pressure for compression molding, and the amount of cement were adjusted, cold-bonded carbon composite agglomerates were produced in which the carbon content (TC) was 15% by mass, 18% by mass, 25% by mass, or 30% by mass and the porosity was 10%, 20%, 30%, or 40%.

[0084] In the same way as in the evaluation process for the burst property in Example 2 except that the heating speed (temperature rise speed) was fixed to 50 ° C / minute, the degrees of disintegration (-6.3 mm%) were measured to assess the breaking properties. Here, the heating speed of 50 ° C / minute is the most severe temperature rise condition in the blast furnace. The results obtained are shown in Table 5 and figure 4.

Table 5

Surf Property; Degree of Disintegration (-6.3mm%) Carbon Content (% in large scale) Porosity (%) 10% 20% 30% 40% 15 20 15 10 5 18 30 20 15 10 25 40 30 25 20 30 50 35 30 25

[0085] As shown in figure 4, it can be understood that the disintegration due to bursting is increased when the content

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29/38 carbon (T.C) in cold-bonded composite carbon agglomerates is increased. This is considered to be due to the matrix resistance of the cold bonded carbon composite agglomerates being decreased when the carbon content (T.C) is increased and so resistance against the pressure of internally generated gas is decreased. Therefore it is necessary to consider the bursting property in the case where the carbon content (T.C) is in a range of 18% by mass or more as in the realization.

(Example 5) (Permissible burst property range) [0086] As described above, it is necessary to set the upper K value to be in a range of 0.4 or less in order to perform stable operations in the actual blast furnace. From the upper limit of the upper K value, the permissible range for the burst property of the cold-bonded carbon composite agglomerates was examined.

[0087] In the same way as in the process for Example 2, except that the combination quantities of the raw raw materials containing iron and the raw raw materials containing carbon, molding pressure for compression molding, and the amount of cement were adjusted, cold-bonded carbon composite agglomerates were produced in which the carbon content (TC) was 20% by mass and the porosities were of various values.

[0088] In the same way as in the evaluation process for the burst property in Example 2, except that the heating speed (temperature rise speed) was fixed to 50 ° C / minute, the degrees of disintegration (-6 , 3 mm%) were measured to assess breaking properties. [0089] Higher K values were measured in the same way

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30/38 as in Example 3 with the use of cold-bonded carbon composite agglomerates at a content of 10% by weight of the total content of iron-based charged substances. The results obtained are shown in Table 6 and figure 5.

Table 6

Breakout Property, Degree of Disintegration; (-6.3mm%) Higher K value (-) 10 0.28 20 0.32 30 0.4 40 0.51 50 0.6

0090] Figure 5 shows a relationship between the bursting property and the upper K value of cold-bonded carbon composite agglomerates having a carbon content (T.C) of 20% by weight. From figure 5, the influence of the burst property on the air permeability of the blast furnace was examined in the case where the cold-bonded carbon composite agglomerates were used at a content of 10% by weight of the total content of charged substances based on iron in the blast furnace.

[0091] From the relationship between the bursting property and the upper K value of the cold-bonded carbon composite agglomerates used in the blast furnace shown in figure 5, it can be understood that the upper K value is raised above 0.4 and it becomes difficult to perform stable operations when the burst property exceeds 30%. Likewise, it is important to decrease the burst property to 30% or less.

[0092] In Examples 2 and 3, it can be understood from figure 2 that the burst property becomes less noticeable in

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31/38 as the porosity becomes greater. In addition, it can also be understood from figure 1 that it is necessary to fix the porosity to be in a range of 20% or more. Referring to figure 4, it can be understood that the burst property becomes 30% or less in the case where the carbon content (TC) is in a range of 25% by mass or less in the carbon composite agglomerates attached to cold having a porosity of 20% or more. In the same way, it can be understood that it is necessary to fix the carbon content (T.C) to be in a range of 25% by mass or less.

(Example 6) (Cold crush strength, reduction rate at 1000 ° C and reducing agent rate in BIS oven) [0093] As in the process for Example 2 except that the combination quantities of the raw materials do not processed materials containing iron and unprocessed raw materials containing carbon, molding pressure for compression molding, and the amount of cement were adjusted, cold-bonded carbon composite agglomerates were produced in which the carbon content (TC) was 15 % by mass, 18% by mass, 25% by mass, or 26% by mass and the porosity was 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0094] For unprocessed raw materials loaded into blast furnaces, resistance to tolerate handling up to blast furnace loading such as transportation, granulation, and the like. As an index of such strength, cold shear strength of cold bonded carbon composite agglomerates was measured in this example.

[0095] Cold crush strength was measured as follows based on JIS M8718 iron ore pellet strength test process. Compression load was loaded onto a sample at a prescribed pressure casserole speed, a

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32/38 load value when the sample breaks was measured, and an average value of 100 samples was evaluated as the cold crush resistance. The results obtained are shown in Table 7 and figure 6.

Table 7

Cold crushing resistance (kg / cm ² ) Porosity (%) Carbon Content (% by mass) 15% in pasta 18% in pasta 25% in pasta 26% in pasta 5.1% 450 400 450 300 10% 470 420 420 250 15.6% 460 410 380 160 20.2% 342 292 300 95 24.8% 220 170 200 60 30% 156 106 100 40 33.9% 88 38 50 0 39.4% 99 49 30 0

[0096] Figure 6 shows a relationship between the porosity and the cold crushing strength of cold-bonded carbon composite agglomerates.

[0097] Referring to figure 6, it can be understood that the cold grinding resistance does not depend on the carbon content and is substantially determined depending on a difference in porosities in the case where the carbon contents (18% by mass, 25% mass) are in the carbon content range according to the realization. With respect to both composite carbon agglomerates having the carbon contents described above, in the case where the porosities were in a range of 30% or more, it was difficult to maintain 100 kg / cm ² which is the lower limit of the cold crush resistance for blast furnace use. Likewise, it is necessary that the porosity is fixed to be in a range of 30% or less from the

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33/38 view of the cold crushing resistance.

[0098] With respect to cold-bonded carbon composite agglomerates having a carbon mass of 26% (which exceeds the upper limit of 25% by mass of the range prescribed in the realization), the cold grinding resistance is less than 100 kg / cm ² (the lower limit for use in the blast furnace) when the porosity is 20% or more. Likewise, it is necessary for the carbon content to be fixed to be in a range of 25% by mass or less. If the amount of combined coke is excessively large, the amount of binder that penetrates the openings in the coke is increased. In the same way, it is considered that it becomes difficult to obtain the strength in an efficient way through binder in the case where the carbon content exceeds 25% by mass.

[0099] Next, for the cold-bonded composite carbon agglomerates obtained, the rate of reducing agent in a BIS oven and the rate of reduction at 1000 ° C were measured as follows and based on a property evaluation test process at the time of use in the blast furnace (BIS oven: see Iron and Steel, 72 (1984), 1529).

[00100] Cold-bonded carbon composite agglomerates at a content of 10% by weight of the total content of iron-based charged substances were uniformly mixed in the ore layers and loaded in the BIS furnace to form a layered structure with a layer of coke. The BIS furnace is a test apparatus for simulating a countercurrent reaction of a shaft part in the blast furnace, and the BIS furnace includes a reaction pipe in which sintered ores (iron ore sintering) and coke are loaded into a structure. layer and an electric furnace of vertical movement type. The amount of charge was adjusted so that the weight ratio of iron oxide to carbon became 5.0. Gas having a quantity of Bosch gas and a

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34/38 composition corresponding to an operation, in which the rate of reducing agent was 480 kg / tp and a blowing rate of fine pulverized carbon (pulverized coal) was 150 kg / tp, was supplied to the BIS oven to be carried out ore reduction.

[00101] Axis efficiency and temperature of the thermal reserve zone in the BIS oven were measured, and the heat and material balance was calculated based on the measured values. The rate of reducing agent in the BIS oven was obtained based on the balance of heat and material.

[00102] In addition, after the ore reduction by the BIS kiln was completed, sintered ores and cold-bonded carbon composite agglomerates at a position of 1000 ° C were collected. Then, chemical analyzes were performed on the sintered ores collected and the cold-bonded carbon composite agglomerates, and the reduction rate at 1000 ° C was obtained from the analysis values. Here, the reduction rate at 1000 ° C represents a reduction property of the total iron-based charged substances including the loaded cold-bonded carbon composite agglomerates.

[00103] The results obtained are shown in Tables 8 and 9 and figures 7 and 8.

Table 8

Reducing agent rate in BIS oven (kg / tp) Porosity (%) Carbon Content (% by mass) 15% in pasta 18% by mass 25% pasta in 5.1% 501 500 481 10% 500 495 477 15.6% 499 483 473 20.2% 498 471 461 24.8% 498 463 453

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Reducing agent rate in BIS oven (kg / tp) Porosity (%) Carbon Content (% by mass) 15% in pasta 18% by mass 25% pasta in 30% 497 461 451 33.9% 497 460 450 39.4% 497 460 450

Table 9

Reduction Rate ) at 1000 ° C (%) Porosity (%) Carbon Content (% by mass) 15% in pasta 18% in pasta 25% in pasta 26% in pasta 5.1% 50 55 69 70 10% 51 58 73 74 15.6% 52 62 77 78 20.2% 53 74 89 90 24.8% 54 82 97 98 30% 54 84 99 100 33.9% 55 85 100 100 39.4% 55 85 100 100 [00104] Figures 7 and 8 show respecl the agent fee

reducing agent and the reduction rate at 1000 ° C in the BIS oven in the case where the cold-bonded carbon composite agglomerates at a content of 10% by weight of the total content of the iron-based charged substances were uniformly mixed in the ore layers. Referring to figures 7 and 8, it can be understood that the rate of reduction at 1000 ° C is increased while the rate of reducing agent is decreased when the carbon content becomes higher. When the carbon content is 15%, the reduction rate at 1000 ° C is markedly decreased, and the efficiency of blast furnace operations is decreased. In the same way, the limit

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36/38 lower carbon content (T.C) is fixed at 18%.

[00105] In addition, the reduction rate at 1000 ° C is improved when the porosity is increased. Even in cold-bonded carbon composite agglomerates having a carbon content (T.C) of 18% by mass, the reduction rate reaches 75% and the reducing agent rate reaches 470 kg / tp when the porosity is 20%. However, in the case where the porosity is less than 20%, a reduction rate enhancement effect at 1000 ° C and reduction rate of reducing agent is limited, and substantially the same result is obtained as that in a case without cold-bonded carbon composite agglomerates. In addition, it was found that the effect of improving the reduction rate at 1000 ° C and reducing the rate of reducing agent was saturated in the case where the porosity exceeds 30%. Therefore, it can be understood that the porosity can be fixed to be in a range of 20% or more to 30% or less for composite carbon agglomerates having a carbon content (TC) of 18% by mass and 25% by weight. pasta.

[00106] From the results above, it can be understood that cold-bonded carbon composite agglomerates in which the carbon content (TC) is in a range of 18 to 25% by mass and the porosity is in a range of 20 to 30% can be used in order to more efficiently exhibit the effects of the degree of disintegration, the burst property, the cold crush resistance, the reduction rate, and the rate of reducing agent in blast furnace operations.

[00107] Here, free water is taken in hydrates in the cold-bonded carbon composite agglomerates due to a hydration reaction of the cement during curing from among the manufacturing processes including mixing, kneading, molding, and curing. Therefore, the total combination amount of raw materials does not

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37/38 processed is slightly varied on manufacturing processes for the above reason; however, the amount of variation is extremely small, and it is possible to consider the amount of total combination to be difficult to change. Therefore, for example, the amount of binder combination is substantially the same as the binder content in the manufactured cold-bonded carbon composite agglomerates. The same is true for the other constituents, and their amounts of combination during manufacturing processes are substantially the same as the levels in the cold-bonded composite carbon agglomerates. Industrial Applicability [00108] Cold-bonded carbon composite agglomerates according to an embodiment of the present invention have a sufficient carbon content to improve not only the reduced rate of cold-bonded carbon composite agglomerates, but also the reduced rate of the main unprocessed raw materials containing iron for blast furnaces such as sintered ores and the like in blast furnace use. In addition, the cold shear strength of 100 kg / cm ² or more is maintained which is required as raw materials for blast furnaces, and superior hot strength is achieved in the reduction temperature range compared to a conventional case. Therefore, it is possible to greatly reduce the rate of reducing agent (coke rate) in blast furnace operations.

[00109] In addition, according to the process for manufacturing cold-bonded carbon composite agglomerates according to an embodiment of the present invention, it is possible to save energy and reduce CO2 compared to a burning process. In addition, it is possible to recycle dust generated in the ironmaking process as raw materials containing iron and

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38/38 carbon (carbonaceous materials) through a relatively simple and inexpensive process.

[00110] Therefore, the realization of the present invention can preferably be applied to a technical field related to the carbon composite agglomerates used in blast furnaces.

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1/1

Claims (2)

1. Cold-bonded carbon composite agglomerates for blast furnaces that are manufactured by mixing and kneading unprocessed raw materials containing iron, unprocessed raw materials containing carbon, and a binder, molding a kneaded substance to obtain a body molded, and then curing the molded body, characterized by the fact that a carbon content (TC) is in a range of 18 to 25% by mass, and a porosity is in a range of 20 to 30%. 2. Method for the manufacture of cold-bonded carbon composite agglomerates for blast furnaces, the method comprising: forming a molded body by mixing and kneading unprocessed carbon-containing raw materials, unprocessed iron-containing raw materials, and a binder and molding a kneaded substance to obtain a molded body; and obtaining cold-bonded carbon composite agglomerates through subsequent curing of the molded body, characterized by the fact that in the formation of the molded body, one or more combination conditions selected from a group consisting of a water content in the raw materials does not processed, a particle size of unprocessed raw materials, an amount of fine coke, an amount of ore combination having a high content of combined water, and an amount of combination of a binder are adjusted so that a carbon content (TC) becomes in a range of 18 to 25% by weight and a porosity becomes in a range of 20 to 30% in cold-bonded carbon composite agglomerates. Petition 870170093591, of 12/01/2017, p. 42/46 1/5