JPH0420970B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing sintered ore, and provides an energy-saving sintering method that reduces the unit consumption of coke. (Conventional technology) Iron ore, serpentine, silica stone, limestone, and coke as a sintering heat source are thoroughly mixed in a mixer using a conventional method, water is added to granulate the mixture, and the mixture is then charged into a sintering machine. do. The surface layer of the granulated product is ignited in the ignition furnace, air is sucked in from the suction duct at the bottom of the sintering machine, and the temperature rises to 1,300-1,400℃ due to combustion of fuel and coke, making the granulated product strong. It becomes a sintered body (Sinter Coke). The sintered ore used in the blast furnace is obtained by crushing, cooling, and sizing (5 to 50 mm) this sintered body. Sintered ore is required to have strong room-temperature strength that can be used in blast furnaces, resistance to low-temperature reduction and powdering performance, etc. Therefore, in order to maintain good quality, it is important to maintain a sintering temperature of 1,300 to 1,400°C during sintering so that the melting reaction can sufficiently proceed. Therefore, depending on the sintering conditions, the basic unit of coke has a large effect on the rise in manufacturing costs. (Problems to be Solved by the Invention) The present invention reduces the coke consumption rate of sintered ore, increases its yield, increases productivity, improves the strength of sintered ore, and improves the low-temperature reduction powdering rate. The aim is to control this to 40% or less. This will be explained in detail below. Sintered ore is charged into the melt furnace and the operation is fully underway. The chemical structure of the sintered ore, which is the main raw material for the smelting furnace, plays an important role in ensuring sufficient separation between the pig iron and the slag. Sintered ore generally has a total Fe content of 56-58% and CaO: 8% by weight.
~11% _{, SiO2} : 5-7%, _Al2O3 : 2.00% or less,
MgO: composition of 2.0% and basicity of 1.4-1.8 (CaO/
SiO ₂ ). After moisture is added to the sintering raw materials blended in the required composition ratio in a mixer using a conventional method, particles of 1 mm or more (hereinafter referred to as core particles) are attached to the sintering raw materials to form pseudo particles. Generally, the residence time of the raw material in the mixer for pseudo-granulation is about 4 to 6 minutes, and the pseudo-granulation particles are charged into the sintering machine, and the coke mixed in the particles is ignited in the ignition furnace. However, the combustion of coke moves to the lower side of the charging layer due to the air introduced from the bottom of the furnace, causing the evaporation of moisture in the charging material and the formation of limestone (CaCO ₃ ).
Decomposition to CaO and _CO2 takes place. At this time, CaO and Fe ₂ O ₃ generated by thermal decomposition,
Adherent particles composed of Al ₂ O ₃ , SiO ₂ , MgO and other impurities undergo a melting reaction, and the molten material is cooled and becomes a bonding medium (hereinafter referred to as bonding melt),
This results in the hard sintered body described above. This reaction is commonly called a sintering reaction. In the production of such sintered ore, the sintering reaction is mainly based on a melting reaction, and this melting reaction is greatly influenced by the component composition of particles acting on the reaction. However, when blending raw materials for sintering, the particle size distribution structure of the raw materials and the component composition of each particle depending on the manufacturer change, so in order to obtain a constant chemical composition of sintered ore, it is necessary to combine adhering particles that undergo a melting reaction and those that are generated by thermal decomposition. It is necessary to control the composition of CaO. (Means for Solving the Problem) For the reasons mentioned above, the present inventor manages the sintering reaction within a range in which the quality of the sintered ore is good, so that By selecting , the amount of coke used as a sintering raw material can be reduced. The present inventor investigated sintered ore with various component compositions through research, and determined the chemical composition of particles involved in the melting reaction in weight percent: Fe ₂ O ₃ : 62.0-66.5%, SiO ₂ : 8.0.
~11.5%, CaO: 20.0 _~ 23.0%, _Al2O3 : 2.8~3.8
%, MgO: If controlled at 1.8%, sintered ore of good quality can be obtained, and at the same time, the normal sintering temperature can be maintained at 1,300 to 1,300 %.
It has been revealed that it is possible to lower the coke consumption rate from 400℃ to around 1,250℃ and keep the coke consumption rate at a low level. (Example) The following will be explained through examples. In the example of the present invention, the chemical composition of the entire sintered ore is: total Fe in iron oxide: 56 ± 0.2%, SiO ₂ : 6.0 ± 0.2
%, CaO: 10.0±0.2%, _{Al2O3 :} 1.7±0.2%,
MgO: 1.8±0.2%, and basicity (CaO/SiO ₂ )
1.7 into a combined melt and the particles involved in the sintering reaction (limestone and iron ore less than 0.5 mm, serpentine,
The composition of the silica stones was classified into 7 groups as shown in Table 1.

[Table] Since limestone participates in the sintering reaction after the decomposition reaction, the basicity of the combined melt changes depending on the amount of SiO ₂ in the attached particles. In the experiment, the composition ratio of CaO and SiO ₂ was kept constant.
i.e. phillips and muan
B ₀ point (eutectic point) at which the lowest melting point occurs in the Fe ₂ O ₃ −CaO−SiO ₂ acid component phase diagram (Figure 1) of
Based on the basicity of 2.5, Fe ₂ O ₃ is converted into A ₀ , B ₀ , C ₀ ,
The composition was set at the point D ₀ , and the composition ratio of CaO and Fe ₂ O ₃ was kept constant, and SiO ₂ was set at the compositions B ₁ , B ₂ , B ₃ , and B ₀ . Sintered ore was produced from the sintered raw materials having the above compositions with coke ratios of 3.5% and 2.9%. The coke consumption rate, yield, and low-temperature reduction powdering rate for each composition were measured, and the results shown in FIG. 2 were obtained. At this time, the low-temperature reduction powdering rate is 500 to 600℃ in the blast furnace.
2.83mm reduced to powder from the nearby reducing atmosphere
The following sintered ores were expressed in terms of weight ratio. According to FIG. 2, although the values of each index differ depending on the coke ratio, it can be seen that the diagram shows almost the same shape for each coke ratio. According to (a) in Figure 2, within the range that does not reduce productivity, when the composition is B ₀ and C ₀ , that is,
It was found that the coke ratio was minimized when the amount of Fe ₂ O ₃ was 61.89 to 66.89%. (b) in Figure 2
According to this, when the composition is B ₀ and B ₃ , that is, the amount of SiO ₂ is
The coke consumption rate and other indices are good in the range of 9.52 to 11.90%, and according to Figure 2 and the ternary phase diagram of Phillips and Muan, the mixing ratio of the sintering raw materials, Fe _{2O3 , SiO2}
And the composition of CaO is within the range of B ₀ , C ₀ , B ₃ respectively, that is, the weight ratio is Fe ₂ O ₃ : 62.0 to 66.5%, SiO ₂ :
When CaO was in the range of 8.0 to 11.5% and CaO was in the range of 20.0 to 23.0%, the coke consumption rate could be minimized while maintaining the quality of the sintered ore. Next, the effect of increasing the amount of Al ₂ O ₃ is on Fe ₂ O ₃ of B ₀ ,
Calculate the amount of Al ₂ O ₃ based on the composition of SiO ₂ and CaO.
We measured the basic unit and quality when increasing the amount to 2.2, 2.4, 2.8, and 3.8. The results are shown in FIG. According to Figure 3,
As the amount of Al ₂ O ₃ increases, the room temperature strength (the room temperature strength is the sintered ore of 10 mm or more after charging 23 ± 0.5 kg of sintered ore of 10 to 50 mm in a 1050 mm cylinder and rotating 200 times at 20 rpm) (expressed as a weight ratio) and the yield were good, but the low-temperature reduction powdering rate deteriorated. The amount of Al ₂ O ₃ is 2.8 to 3.8% by weight with a controlled value of low temperature reduction powdering rate of 40% or less
It was found that the contribution of coke to unit savings is large in the case of The amount of MgO is approximately 1.8% by weight, and the remainder is unavoidable impurities. (Effect of the invention) From the above results, the composition of particles involved in the melting reaction is determined to be Fe ₂ O ₃ : 62.0 to 66.5 and SiO ₂ : 8.0 to 66.5 by weight.
11.5, CaO: 20.0 _~ 23.0, _Al2O3 : 2.8~3.8, MgO
and other impurities, if carried out within the range,
It has become clear that producing 1 ton of sintered ore can sustainably reduce the coke consumption by approximately 3 kg, and at the same time produce good quality sintered ore.

[Brief explanation of drawings]

Figure 1 is the ternary phase diagram of Fe ₂ O ₃ −SiO ₂ −CaO,
Figure 2 is a diagram showing the coke consumption rate, yield, quality, etc. when sintered ore is manufactured with each composition in Table 1, and Figure 3 is a diagram showing the effect of Al ₂ on coke consumption rate, yield, and quality. FIG. 3 is a diagram showing the influence of O ₃ .

Claims (1)

[Claims] 1 Total Fe in iron oxide in weight percent: 56.0~
58.0%, _SiO2 : 5.0-7.0%, CaO: 8.0-11.0%,
In the method for producing sintered ore with a structure of Al ₂ O ₃ : 2.0% or less and MgO: 2.0% or less, the limestone involved in the dissolution reaction is calculated as CaO, and the structure of adhered particles of 0.5 mm or less is Fe ₂ in weight percent. _O3 : 62.0~66.5, _SiO2 :
8.0 _~ 11.5, CaO: 20.0~23.0, _Al2O3 : 2.8~3.8,
A method for producing sintered ore characterized by containing MgO and other impurities.