KR20130066238A - Method for manufacturing sintered ore by using fine iron ore with high alumina content - Google Patents

Abstract

PURPOSE: A method for manufacturing sintered ore using iron ore fine with high contents of alumina is provided to increase the productivity of sinter, and to reducing sintering time by adding 4-5mm pellets into sintered materials. CONSTITUTION: A method for manufacturing sintered ore using iron ore fine with high contents of alumina comprises following steps. Water is added into sintered materials containing iron ore, supplementary materials, and fuel. The pellets are manufactured by mixing high-alumina iron ore fine with 3-4 weight% of AL2O3, low-alumina iron ore fine with less than 0.5 weight% of Al2O3, and assembly binders. The second assembly is performed by adding the pellets into the sintered materials. [Reference numerals] (AA) Iron ore; (BB) Supplementary material; (CC) Semimat; (DD) Fine coke + anthracite; (EE) High AI_2O_3 fine iron ore; (FF) Low AI_2O_3 fine iron ore; (GG) Binder for assembly

Description

METHODS FOR MANUFACTURING SINTERED ORE BY USING FINE IRON ORE WITH HIGH ALUMINA CONTENT}

The present invention relates to a method for producing a sintered ore using a high iron content of alumina.

In the conventional DWIGHT LLOYD type sintering process, iron ore, subsidiary materials (limestone, limestone, silica sand, etc.) and fuels (powdered coke, anthracite coal), etc. are put into a drum mixer to mix and water (raw material weight ratio). 7-8%) of the sintered blended raw material is made into pseudo-particles and charged to a certain height on the sintering machine bogie, and the surface of the sintered blended raw material is forced to suck air from below after ignition. Firing advances and a sintered ore is manufactured. After sintering is completed, the sintered ore is cooled by a crusher (crusher) in the light distribution unit, cooled to a cooler (cooler), classified into a particle size (5 to 50 mm) that is easy for charging and reaction in the blast furnace, and then transferred to the blast furnace.

In order to efficiently proceed the sintering reaction in the DL type sintering process and to produce a good quality sintered ore, it is important to secure air permeability so that an appropriate amount of air flows in the layer, and the sintering productivity is greatly influenced by the layer air permeability. Breathability in the sintered layer is also affected by the particle size distribution of the pseudo particle, there is a problem that the productivity decreases due to the increase of the sintering time when the ultra-fine fraction of the blended raw material increases.

In addition, when high alumina (Al ₂ O ₃ ) ore is used as a raw material for sintering, in terms of sintering operation, the melting point of the sintered melt and the decrease in fluidity decrease the strength and recovery of the sintered ore, resulting in a decrease in productivity. There is a problem that the low-temperature reduction differentiation index (RDI) of the sintered ore deteriorates due to the crystal structure instability due to the Al ₂ O ₃ solid solution. In addition, the blast furnace slag volume (slag volume) is increased in terms of blast furnace operation, due to the increase in viscosity due to the Al ₂ O ₃ component in the slag deterioration of slag discharge characteristics and blast furnace operation instability.

On the other hand, in the recent steelmaking process, Al ₂ O ₃ content of blast furnace slag is continuously increased due to the increase in the use of low-grade iron ore, approaching the management limit (16.5% or less). However, in the sintering process according to the conventional method, such high alumina ore is not used as a sintering raw material, and mainly iron ore having an Al ₂ O ₃ content of about 1 to 2.5% by weight has been used as a sintering raw material.

One aspect of the present invention is to provide a method for producing a sintered ore using a high content of alumina (Al ₂ O ₃ ) and iron ore and fine iron ore that has been avoided due to problems in the prior art.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

One aspect of the present invention, the step of primary granulation by adding water to the sintered blended raw materials including iron ore, secondary raw materials, semi-ores and fuel, high alumina powder having 3 to 4% by weight of Al ₂ O ₃ component Preparing a selective assembly by mixing iron ore, low alumina ferrous ore containing 0.5 wt% or less of Al ₂ O ₃ and a binder for assembling, and then pelletizing the selective assembly; and Provided is a method for producing a sintered ore using a high alumina content of iron ore, including the step of secondary granulation in addition to the completed sintered blended raw material.

According to an aspect of the present invention, it is possible to obtain a sintered ore with improved productivity and quality while utilizing high alumina iron ore and fine iron ore.

1 is a schematic diagram of a method of manufacturing a sintered ore according to a conventional method.
Figure 2 is a schematic diagram of a method of manufacturing a sintered ore according to an embodiment of the present invention.
3 is a structural diagram of a sintering pot tester (or sintering tester) generally used.

DETAILED DESCRIPTION Hereinafter, embodiments and embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and examples described herein.

Hereinafter, a method of manufacturing a sintered ore using a high iron content of alumina of the present invention will be described in detail with reference to FIGS. 1 to 3.

One aspect of the present invention, by the addition of water to the sintering blended raw material containing iron ore, additives, semi-glossy and fuel assembling primary, Al ₂ O ₃ component is 3 to 4% by weight high alumina fine iron ores, Al ₂ Mixing a low alumina ferrous ore containing 0.5 wt% or less of O ₃ and a binder for granulation and then pelletizing to prepare a selective assembly, and sintering blended raw materials in which the primary assembly is completed In addition to the second step of the step of providing a method for producing a sintered ore using a high alumina content iron ore.

Conventionally, a sintered ore was manufactured through a process proceeding as shown in FIG. 1. That is, the sintered blended raw material composed of iron ore, secondary raw materials, semi-ores, and fuel as powdered coke or anthracite coal is granulated (11, 12) together with water addition in a drum mixer, and then granulated and charged into a sintering tester (16). Go through the process.

However, in the present invention, as shown in Figure 2 by adding a new process in the middle of the conventional process was to find a way to use a high alumina iron ore and low alumina iron ore together.

Looking specifically, Al ₂ O ₃ component of from 3 to 4%, an average particle size an average particle size of 2.0 to 3.5mm and containing a high alumina fine iron ores, Al ₂ O ₃ component to less than 0.5% by weight and containing 0.05 weight to 0.1mm After mixing the low alumina ferrous ore and the binder for assembly in a high speed stirring mixer 13 and pelletizing in a pelletizer 14 to produce a selective assembly (15), the primary granulated (11) Adding the optional assembly to the sintered blending raw material further comprises the step of secondary assembly 12 in the secondary drum mixer.

Granulation refers to the manufacture of pseudo particles of sintered blended raw materials in the sintering process (particles are added by attaching fine particles to around the nucleus particles to add moisture). 1st and 2nd assembly are performed by connecting. In the 1st granulation process, the mixing function of powder is large with water addition, and in the 2nd granulation process, the pseudo granulation function by the rolling of the powder is large.

The assembling binder may be used without limitation as long as it is industrially commercially available, and the total amount of the assembling binder is 3 to 8% by weight based on the total weight of the high alumina iron ore and the low alumina iron ore. Considering the function and cost aspects of the is preferable.

In the recent steelmaking process, Al ₂ O ₃ content in the blast furnace slag is continuously increased due to the increase in the use of low-grade iron ore, which is close to the management limit (16.5% or less), but it is not properly utilized. High-alumina in using a sintering operation side the ore in the sintering raw material, productivity is lowered by the sintered ore strength and the recovery rate decreased as the melting point rises and the fluidity deterioration of sintering the melt, the secondary hematite from generating the melt of the Al ₂ O ₃ employed during crystallization Crystal structure instability deteriorates the low temperature reduction index (RDI) of the sintered ore. In terms of blast furnace operation, the blast furnace slag volume is increased, and the viscosity increases due to the increase of Al ₂ O ₃ component in the slag causes deterioration of slag emission and blast furnace operation instability.

On the other hand, in the DL type sintering process, in order to efficiently proceed the sintering reaction and to manufacture good quality sintered ore, it is important to secure air permeability so that an appropriate amount of air flows in the layer, and the sintering productivity is greatly affected by the layer air permeability. . In particular, when using an ultrafine iron ore having an average particle size of 0.1 mm or less and a particle size of 0.15 mm or less, 90 wt% or more, air permeability is poor and sintering productivity is low. The air permeability in the sintered layer is also affected by the particle size distribution of the pseudoparticles, and in order to improve the air permeability, it is effective to reduce the proportion of fine powder rather than increase the average particle diameter. Therefore, there is a need for a pretreatment process for minimizing the fraction of sintered raw materials.

In order to improve the sintering productivity and the quality of the sintered ore while solving the problems of the high alumina iron ore and ultra fine iron ore as described above, the present invention contains 3 to 4% by weight of Al ₂ O ₃ component in the iron ore during the production of sintered ore for blast furnace Exploring the use of high alumina iron ore as sintering raw material. However, since the Al ₂ O ₃ content is almost 4% by weight or more in commercially available sintered iron ore, the upper limit is 4% by weight, but the ore containing more alumina is not excluded. Here, high alumina powdered iron ore means sintered iron ore having an average particle size of 2.0 to 3.5 mm while containing 3% by weight or more of Al ₂ O ₃ components relative to the total weight of the iron ore.

In addition, when using iron ore having a very fine powder ratio such as ultra fine iron ore, the method of using as a raw material for sintering through separate pretreatment was also considered.

Therefore, Al ₂ O ₃ in the blended raw material In order to suppress the increase of the components and to improve the sinterability, in addition to the high alumina iron ore and low-alumina iron ore and granulation binders were prepared green pellets (green pellets) having an average particle size of 4 ~ 5mm to prepare a selective assembly. In addition, the selective assembly was introduced into a conventional sintering compound raw material assembling process, and the sintering was performed after the secondary granulation 12 in the secondary drum mixer, thereby improving the sintering productivity and quality. Here, low alumina iron ore refers to iron ore having an average particle size of 0.05 to 0.1 mm while containing Al ₂ O ₃ component in an amount of 0.5% by weight or less relative to the total weight of the iron ore.

Iron ore used in the conventional method is not limited to hematite, brown iron or the like, Al ₂ O ₃ In terms of the content of the component, Al ₂ O ₃ as distinguished from the high alumina iron ore of the present invention It means iron ore containing less than 3% by weight of the component. And the subsidiary materials may include, but are not limited to, quicklime, limestone, silica. As the fuel, powdered coke, anthracite, or the like may be used.

In addition, in addition to the particle size distribution of the pseudoparticles in the sintering process, the strength significantly affects the breathability of the sintered layer, and the breathability is desirable to have the strength to withstand the mechanical and thermal shocks that the granules undergo during transportation, charging, and firing. Do. Good ventilation makes it easy to adjust the productivity and quality of the sintered ore. Therefore, in the assembly process, it is important to make a pseudo particle having a strength that can secure a constant breathability despite the change of raw material properties (particle size, etc.).

To this end, in the present invention, after the selective assembly is made, the dropping strength before drying is 30% or more, and the dropping strength after drying is 50% or more. The strength of the optional assembly is necessary to maintain the structure of the pseudo particle layer in the drying zone under the hot melting zone during the sintering process. As the drop strength increases after drying of the optional assembly, the upper limit is not particularly specified because the breathability of the sintered layer is good. However, if the drop strength index of 50 ~ 80% level sintered layer is more breathable.

Hereinafter, the present invention will be described in detail by way of examples.

[ Comparative example ]

As shown in Table 1 and Table 2, various iron ores were prepared and blended.

ironstone Chemical composition (wt.%) Average particle size
(mm) 0.15mm
Below Total Fe FeO SiO ₂ Al ₂ O ₃ CaO MgO A 62.98 0.00 3.02 1.46 0.06 0.08 2.03 18.9 B 65.55 0.24 1.62 1.57 1.72 0.17 2.29 21.7 C 58.15 0.07 5.29 1.42 0.04 0.04 3.27 6.0 D 61.65 0.07 3.51 2.06 0.01 0.04 1.85 19.9 E 56.43 0.05 5.51 3.23 0.08 0.07 3.50 13.0 F 66.74 0.47 2.41 0.40 0.02 0.03 0.09 92.0 G 68.33 26.56 2.63 0.05 0.11 1.42 0.07 90.0

Table 1 shows the chemical composition and the particle size of each iron ore used.

division Formulation-1 Formulation-2 Formulation-3 Particle size (mm)
ironstone
(wt.%)



A 12.4 7.4 7.4 8 or less B 13.4 7.9 7.9 8 or less C 34.9 20.6 20.6 8 or less D 3.9 2.3 2.3 8 or less E 0 11.4 11.4 8 or less F 0 15.2 0 0.1 or less G 0 0 15.2 0.1 or less
Supplementary material
(wt.%)
quicklime
Limestone
Silica sand 1.6
9.2
0.4 1.6
9.2
0.4 1.6
9.2
0.4 1 or less
3 or less
1 or less Semigloss (wt.%) 19.9 19.9 19.9 5 or less Powder Coke (wt.%) 1.8 1.8 1.8 3 or less Anthracite (wt.%) 2.5 2.5 2.5 3 or less Total (wt.%) 100.0

Table 2 is a compounding table consisting of three different mixing ratios of powdered coke and anthracite as iron ore and subsidiary materials, semi-ores, and fuels.

In order to manufacture the sintered ore by the conventional method (FIG. 1), the process was carried out by mixing according to the above Formulation 1, 2 and 3, and finally, CaO: 8.9 wt%, SiO ₂ : 5.0 wt%, MgO : 0.6 wt%, Al ₂ O ₃ : 1.7 wt%, slag volume: 16.3 wt%, basicity (CaO / SiO ₂ ratio): 1.8 to obtain a sintered ore to measure the productivity and quality.

[ Honor ]

In order to manufacture the sintered ore by the method of the present invention (FIG. 2), in the formulation-2 and the formulation-3 of Table 2 above, the iron ores A, B, C, and D are added to the primary granulation process, and the iron ores E and F , G is added to the process of making a selective assembly, and then a sintered ore is prepared to finally produce CaO: 8.9 wt%, SiO ₂ : 5.0 wt%, MgO: 0.6 wt%, Al ₂ O ₃ : 1.7 wt%, slag volume : 16.3 wt%, basicity (CaO / SiO ₂ ratio): 1.8 to obtain the sintered ores was measured productivity and quality. The compounding table is shown together in one table in order to apply equally to the conventional method and the method of the present invention in terms of the addition amount of the main substances used.

The mixing ratio is similar to the actual raw material conditions of the sintering process, iron ore is two types of hematite spectroscopy (A, B), two types of hematite spectroscopy (C, D), high alumina iron ore (E) and low Two alumina ferrous ores (F or G) were used. In the formulation 1, the blending ratio of high alumina powdered iron ore (E) was 0% by weight, and in the blending 2 and blend-3, 11.4% by weight of the high alumina powdered iron ore (E) was blended with Al ₂ O ₃ of the sintered blended raw material. In order to maintain the same content, low alumina iron ore (F or G) was blended in 15.2% by weight. 9.2% by weight of limestone, 1.6% by weight of quicklime, and 0.4% by weight of silica sand were used, and 19.9% by weight of semi-glossy and 4.3% by weight of coke and anthracite were used as fuels. Al ₂ O ₃ content of the prepared sintered ore 1.7 wt%, slag amount 16.3 wt%, basicity (CaO / SiO ₂ ratio) was maintained at the same level of 1.8.

The chemical composition and particle size of the iron ore used in the present invention can be confirmed through Table 1. Al ₂ O ₃ content of hematite (A, B) and hematite spectroscopy (C, D) in terms of the composition of iron ore is about 1.4-2.1 wt.%, Whereas Al ₂ O ₃ of high alumina iron ore (E) The content was the highest at about 3.2 wt.%, And the Al ₂ O ₃ content of the _two low-alumina iron ores (F, G) was very low at 0.05 to 0.4 wt.%. In addition, in terms of the particle size of the iron ore, two low-alumina iron ores (F, G) have an average particle diameter of 0.07 to 0.09 mm, and the differential ratio (weight ratio of particles of 0.15 mm or less) exhibits an ultra fine powder characteristic of about 90 to 92 wt.%. .

2 shows a schematic diagram of a method for producing a sintered ore according to the present invention. In the sintering pot test, sintered blended raw materials consisting of iron ore, minor raw materials, semi-ores, and fuel, except high alumina iron ore (E) and low alumina iron ore (F, G), are added to the drum mixer for 2 minutes. Car assembly (11) was carried out, at which time the granulated water secretion was set to 7.5%. On the other hand, the selective assembly was prepared using a binder for assembly 4% on the basis of the high alumina iron ore (E) and low alumina iron ore (F or G). Molasses and industrial CaO were used as granulation binders, and 2.5% by weight of molasses and 1.5% by weight of industrial CaO were added based on high alumina iron ore (E) and low alumina iron ore (F or G). At this time, the high alumina powdered iron ore (E) and the low alumina powdered iron ore (F or G) is uniformly mixed for 3 minutes with the addition of a binder for assembling in the high speed stirring mixer 13, and then the pelletizer 14 A spherical selective assembly 15 was prepared by pelletizing for 6 minutes. This was added to the primary granulated sintered blending material, followed by secondary granulation 12 for 2 minutes in a drum mixer, and uniformly mixed to prepare a final granulated product for sintering.

Table 3 shows the particle size and the drop strength of the selective assembly 15 according to the present invention.

division High Alumina Iron Iron Ore (E) +
Low Alumina Ferrous Ore (F) High Alumina Iron Iron Ore (E) +
Low Alumina Iron ore (G) ore
Mixing ratio
(wt.%) E 42.8 42.8 F 57.2 0 G 0 57.2 Binder (wt.%) 4.0 4.0 Assembly
Particle size (mm) 8 or more 0.3 1.8 5 or more 36.8 27.1 3 or more 43.8 43.2 1 or more 12.0 18.1 1 or less 7.2 9.8 Average particle size 4.46 4.08 Assembly
Drop strength (%) Before drying 34.1 46.4 after drying 55.5 55.2

The average particle diameter of the obtained selective assembly is 4 to 5 mm, and the proportion of 1 to 5 mm granulated particles is about 90% or more. In addition, the drop strength of the selective assembly was obtained by the following formula (1), after the three-times drop of the prepared 4 ~ 6mm optional assembly (600g) three times at 2m height to define the weight ratio (g) of particles of 4mm or more as a percentage. It was. The drop strength of the selective assembly before drying was 34-46% and 55% after complete drying.

3 shows a structural diagram of a sintering pot tester. The sintered blended raw materials completed until the second assembly as described above was charged to the sintering pot (250 mm in diameter, 600 mm in height) 21, and the loading density was maintained at 1.9 t / m ³ level. After the charging was completed, the ignition furnace 31 preheated to 1050 ° C. was moved to the upper portion of the pot, and after ignition (1 minute), the negative pressure was measured through a negative pressure gauge 28 to proceed to sintering with a negative pressure of 1,500 mmAq. Was investigated. Productivity, recovery rate, rotational strength and low temperature reduction rate (RDI) of the manufactured sintered ores were calculated by the following equations (2) to (5), and the sintering time was based on the time when the exhaust gas 30 reached the maximum temperature. Decided. The firing side temperature was sensed through a thermocouple (R-type) 23, the temperature of the exhaust gas was measured via a thermocouple (K-type) (26).

Table 4 shows the results of the sintering pot test according to the comparative example and the invention example of the present invention.

division
Comparative example Honor Formulation-1 Formulation-2 Formulation-3 Formulation-2 Formulation-3 Productivity (t / d / m ² ) 36.4 35.3 34.4 37.0 36.6 Sintering time (minutes) 20.1 21.0 22.5 20.0 21.3 Recovery rate (%) 64.8 64.9 65.5 64.4 65.6 Rotational strength (%) 69.3 68.6 69.2 68.4 69.1 RDI (%) 46.6 50.7 49.8 46.5 45.2

11.4% high alumina powdered iron ore (E) is blended as in compound 2 and compound-3, and 15.2% low alumina powdered iron ore (F or G) is mixed to maintain the same Al ₂ O ₃ content of the sintered blended raw materials. In one case, according to the conventional method for processing sintered blended raw materials, the productivity decreased due to the increase of the sintering time while increasing the proportion of the fine powder in the blended raw materials, and the RDI of the sintered ore increased.

However, by the method of the present invention, when the selective assembly of the average particle size of 4 ~ 5mm size consisting of high alumina powdered iron ore (E) and low alumina powdered iron ore (F or G) is prepared and added to the sintered blending raw materials, Compared to the method of sintering time is shortened, sintering productivity is increased. In addition, the strength and recovery rate of the sintered ore obtained by the present invention can be maintained at the same level as in the conventional method, and the low temperature reduction index (RDI) of the sintered ore is also improved. As such, in the present invention, a high-alumina iron-iron ore (E) and low alumina iron-iron ore (F or G) are used to prepare a selective assembly having an average particle size of 4 to 5 mm and assemble together with the existing sintered compound raw material to make high alumina ore. (E) Al ₂ O ₃ of sintered blended raw materials according to use It can be seen that the effect of improving the sintering productivity and quality together with the suppression of component rise is exhibited.

11: 1st Assembly 12: 2nd Assembly 13: Mixing in a High Speed Stirring Mixer
14: Pelletizing in the Pelletizer 15: Optional Assembly
16: Sintered 21: Sintered pot 22: Sintered blended raw materials
23: thermocouple (R-type) 24: upper light 25: windbox
26: thermocouple (K-type) 27: Great Bar 28: negative pressure gauge
29 valve 30 sintered flue gas 31 ignition furnace

Claims (6)

Primary granulation by adding moisture to the sintered blended raw material including iron ore, secondary raw materials, semi-ores and fuels;
Al ₂ O ₃ component is 3 to 4% by weight high alumina fine iron ores, Al ₂ O ₃ component and then a mixture of a low alumina minutes binder for iron ore and assembly included in an amount of not more than 0.5 wt% pellet palletizing by the selected granulated Manufacturing; And
And sintering ore by adding the selective assembly to the sintered blended raw material of which primary granulation is completed. The method of claim 1,
The high alumina powdered iron ore has an average particle size of 2.0 to 3.5mm, a method of producing a sintered ore using a high alumina-ferrous iron ore. The method of claim 1,
The low alumina powdered iron ore has an average particle size of 0.05 to 0.1mm, a method for producing a sintered ore using a high alumina-containing iron ore. The method of claim 1,
The average particle size of the selective assembly is 4 to 5mm, a method for producing a sintered ore using a high alumina content iron ore. The method of claim 1,
The total amount of the binder for assembling is 3 to 8% by weight relative to the total weight of the high alumina iron ore and low alumina iron ore, the production method of the sintered ore using a high alumina content iron ore. The method of claim 1,
Drop strength after complete drying of the selective assembly is 50% or more, a method for producing a sintered ore using a high alumina-ferrous iron ore.

Images