JPS62188733A - Manufacture of sintered ore - Google Patents

Abstract

PURPOSE:To control quality characteristics of sintered ore into the desired range, by forecasting an index value of low temp. reduction powdering of sintered ore product from a prescribed condition at manufacturing stage of sintered ore, and adjusting arranging ratio of sintering material and moisture quantity at pelletizing so that the forecast value is approached to the aimed value. CONSTITUTION:Sintering material is charged to a prescribed sintering machine and iron ore is sintered while maintaining working conditions such as pallet speed, intake air quantity, charged layer thickness of sintering material. In this time, pseudo pellet diameter is calculated from arranging ratio of sintering material and moisture value at pelletizing, and +1,100 deg.C holding time is calculated thereby. Next, Al2O3/SiO2 ratio of molten part at sintering is obtd. from arranging ratio and chemical compsn. of sintering material, and powdering index value of low temp. reduction is forecast from calculated +1,100 deg.C holding time and Al2O3/SiO2 ratio of molten part. Then, arranging ratio of sintering material and/or moisture quantity at pelletizing is adjusted so that the forecast value is approached to the aimed value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing sintered ore. In more detail, the low reduction of sintered ore has a large impact on the stability of blast furnace operation and the fuel ratio. The present invention relates to a method for producing sintered ore in which the quality characteristics of sintered ore are controlled to fall within a desired range.

[Prior art] Since sintered ore makes up the majority of the iron ore charged into a blast furnace, the low-temperature reduction pulverizability and reducibility of sintered ore greatly affect the stability of blast furnace operation and the fuel ratio. Left and right. In other words, if the sintered ore undergoes significant low-temperature reduction and powdering, it will be reduced and powdered in the low-temperature region of the blast furnace (300 to 700°C region in the upper part of the shaft).
This sintered ore powder affects the ventilation inside the furnace, causing unstable furnace conditions such as slipping and hanging. Furthermore, if the reducibility is low, the amount of gas that is reduced in the lump state will be reduced, the gas utilization rate of the blast furnace will be reduced, and the blast furnace fuel ratio will be increased. Therefore, the low-temperature reduction pulverizability and reducibility of sintered ore are important quality characteristics for blast furnace operation, and operations have traditionally been conducted by setting management target values for these.

Conventionally, in order to find out whether or not this management target value is satisfied, a part of the produced sintered ore is periodically sampled, and the low-temperature reduction powdering property is measured using the low-temperature reduction powdering index (hereinafter referred to as RDI). We also conduct tests to measure the reducibility as the reduction rate (hereinafter referred to as Il+). In this case, the Low Temperature Reduction Indication Index (IIDI) is determined by heating 500 g of a sintered ore sample at 550°C with a reducing gas containing 30% CO and the balance N2.
× After 30 minutes of reduction treatment, this was made into 130mmφX 200
Pour it into a mmL barrel, rotate at 30 rpm for 30 minutes to powder, and measure -3 mm (X) and note it down. In addition, the return rate (Il+) is based on JIS M 871
Tests have been conducted in accordance with 3D.

[Problem that the invention seeks to solve]

Conventional management of low 4-reducibility and unidimensionality of sintered ore is based on the actual measured values of the produced sintered ore, that is, the target value and the actual measured value are compared. However, if the difference is outside the threshold value, feedback control is performed to adjust the sinter manufacturing conditions so that they are close to the target value, which causes a large time delay and makes it difficult to calibrate the actual measured value. For example, the production of sintered ore involves many steps such as raw material blending, mixing, sintering, pulverization, and cooling, so it is necessary to adjust the process once the actual measured values are obtained. Even though
Because of this time delay, defective products will occur during that time, resulting in a decrease in yield.

It is quite difficult to ensure accuracy in the adjustment operation. Furthermore, in order to find out whether or not the measured values of the low-temperature reduction pulverization index and reduction rate are abnormal values, it is necessary to conduct a large number of tests. Therefore, the conventional management of the low-temperature reduction powderability and reducibility of sintered ore is an extremely complicated and labor-intensive task, and it tends to have many problems in terms of the production yield and precision of sintered ore. .

The object of the present invention is to solve such problems.

[Means to solve problems]

In order to achieve the above-mentioned object, the present invention provides l? Predict the DI value and Ill value 2
The purpose is to achieve the above objective by manipulating this predicted value so that it approaches the target value, and the manipulated variables are feedforward using the blending ratio of sintering raw materials and the amount of water during granulation. The present invention provides a controlled method for producing sintered ore.

That is, in the present invention, a sintering raw material is loaded into a predetermined sintering machine,
In producing sintered iron ore while maintaining the operating conditions of the sintering machine, such as pallet speed, suction air volume, and sintering material loading layer thickness, within the set value range.

(1) Calculate the pseudo grains and diameter after granulation from the blending ratio of the sintering raw materials and the moisture content during granulation, predict the high temperature holding time during sintering from this pseudo grain size, and The A7!20*1SiOt ratio of the molten part during sintering is determined from the blending ratio and chemical composition, and the low-temperature reduction powdering index of the sintered ore is predicted from the high-temperature holding time and the Ae zo3/5iOz ratio. A method for producing sintered ore, which comprises adjusting the blending ratio of sintering raw materials and/or the amount of water during granulation so that the predicted value of the 4-reduction morphing index approaches the target value.

and.

(2) Calculate the pseudo particle size after granulation from the blending ratio of the sintering raw materials and the moisture content during granulation, calculate the maximum temperature during sintering from this pseudo particle size to 1γ, and calculate the maximum temperature during sintering. The porosity after sintering is predicted from the relationship with the amount of void reduction, and the area ratio of the calcium ferrite phase and the area ratio of the primary hematite in the sintered ore ifL are calculated from the blending ratio of the sintered raw materials.
The reduction rate of the sintered ore can be predicted from the porosity, the area ratio of the calcium ferrite phase in the sintered ore mineral, and the area ratio of the primary hematite. IL, a method for producing sintered ore characterized by adjusting the blending ratio of sintering raw materials and/or the amount of water during granulation so that the predicted value of the reduction rate approaches the target value. be.

The contents of the present invention will be specifically explained below based on tests conducted by the present inventors.

Figure 1 shows the sintering pot device used in the test. Reference numeral 1 designates a sintering pot, in which a sintering raw material 3 is loaded onto a rostrum 2 and sucked from below the sintering pot 2 by exhaust air a4. At this time, a damper 6 is interposed in the air chamber 5 below the Rosdol 2, and the amount of suction air is adjusted by the device of the damper 6. During sintering, the coke present on the upper surface of the sintering raw material 3 is ignited by propane gas, and the sintering raw material is sintered and sintered while downward suction is performed by driving the exhaust fan 3. As a result of conducting numerous sintering tests using such test equipment, we found that the low-temperature reduction index (RDI) was determined by the sintering temperature holding time during sintering and the A120 of the molten part.
It was found that there is a close relationship with the 3/SiO□ ratio.

FIG. 2 shows the results of investigating the relationship between high temperature retention time during sintering and RDI while keeping the blending conditions of the sintering raw materials constant. In other words, the blending conditions of the sintering raw materials are the same, and the suction air volume by operating the damper 6 and the granulation conditions (
By changing the pseudo particle size of the sintering raw material, the time for which it is held at a high temperature of 1100°C or higher during sintering (hereinafter referred to as
+1100℃ holding time) is changed, and this +
1100°C holding time and RDI (according to the test described above)
%) is plotted. From Figure 2,
It can be seen that the RDI increases with a constant relationship as the holding time (minutes) at +1100°C increases.

FIG. 3 shows the measurement results of the melting ratio during sintering for each particle size of each brand of iron ore in the sintering raw material. As shown in Figure 3, the melting ratio differs depending on the two particle sizes, and the degree of melting also differs depending on the brand. Normally, the generation of melt in the high temperature range during sintering starts from the surface layer of the sintering raw material, and even if the fine particles are completely melted, the sintering ends with the center of the coarse particles unmelted. The results in Figure 3 show that the melting ratio of fine particles increases, and that the melting ratio of each brand varies depending on the composition of the ore, such as the density of the ore and differences in the content, even if the particle size is the same. It shows that each is different. The inventors.

As a result of calculating the chemical composition of the molten part during sintering from the melting ratio and chemical composition of each particle size of the various sintering raw materials used in the test, and examining the relationship between the calculated chemical composition and RDI in detail,
It has been found that RDI has a close relationship with the A'zos/SiO□ ratio of the molten zone. FIG. 4 shows this relationship.

As shown in Figure 4, when various sintering raw materials are sintered with a constant holding time of +1100°C, the I?
I) What about I? As the A j2 zo*1 SIOz ratio of the 8 melting zone increases, it increases with a certain relationship. therefore.

From the relationship in Figure 4 and the relationship in Figure 2 above, the low temperature reduction pulverization index (1101) of sintered ore is +1100°C.
It can be predicted based on the holding time and the A 1 zoi/SiO□ ratio of the melted zone.

On the other hand, the holding time at +1100°C has a correlation with the pseudo particle size of the sintering raw material, as long as the sintering conditions such as ventilation amount and layer thickness remain unchanged. Figure 5 shows this correlation. Here, the pseudo particle size after mixing and granulating the sintering raw materials can be determined by the following procedure.

Of the particle size composition of the sintering raw material determined from the blending ratio.

Adhering -0.25mm part, 0.25~0.5mm
The parts can be empirically expressed by the following equations (1) and (2), respectively.

Proportion of the -0.25 mm portion of the sintered raw material becoming adhered powder by mixing and granulation (χ) = 0.49 X + 2.6
9...fi+0.25~0.5m in sintering raw material
Proportion of part m becoming adhered powder due to mixed granulation (χ) =
1.79 X -285,04...(2) Here,
X = 190+19. + -11a2.

Saturated moisture value of sintered raw material a-Moisture value during mixed granulation-□ It is.

Particle size composition of core particles in sintering raw material - Particle size composition of sintering raw material - Particle size composition of attached powder... (3)
and the pseudo particle size is.

Pseudo particle size=average diameter of core particles+18.13X amount of adhered core particles per unit surface area (g/cm2) (4).

Therefore, the pseudo particle size can be calculated from the blending ratio of the sintering raw materials and the moisture value at the time of mixing and granulation, and from this pseudo particle size +110
The 0°C holding time can be calculated, and the calculated +1lOO°C holding time and the A 1 zox/SiO□ of the molten part
ROT can be predicted from the ratio.

On the other hand, regarding reducibility, which is another quality characteristic of sintered ore,
After conducting extensive research into methods for predicting this,
It was found that R1 can be described by the mineral phase and porosity of the sintered ore. That is, as a result of repeated detailed tests and analyzes of various sintered ores, the present inventors found that R1 can be described by the following equation (5).

R1(χ) = a+bx+cy+dz
...(5 squares.

×: Area ratio of calcium ferrite in the mineral phase of sintered ore (%) y: Area ratio of primary maquito in the mineral phase of sintered ore (%)
) Z: Porosity (%).

a = 15.246. b==0.193. c.
= −0,303°d = 0.967.

Therefore, if the independent variable X+y+2 can be estimated from manipulated variables such as the blending ratio of the sintering raw materials and the moisture value during granulation, the RI value can be predicted.

According to numerous tests conducted by the present inventors, the area ratio of calcium ferrite in the mineral phase of sintered ore (hereinafter c, f, (χ)
It was found that the area ratio of primary maquito in the mineral phase of sintered ore (hereinafter referred to as p, Otsu (X)) can be estimated by the following procedure.

Figure 6 shows that only a single brand of iron ore is used as the sintering raw material, silica sand and limestone are added so that 5iOz = 5.5%, basicity is -1.6, and 4% coke powder is added. c, f of the sintered ore obtained when sintering.

(χ) and p, r, (χ) are shown for each brand. As shown in Figure 6, the proportions of c, f, (χ) and p, otsu (χ) mineral phases have fixed values that vary depending on the brand of iron ore. By adding a predetermined weight according to the blending ratio of the brand when blending stones, c, f, (χ), p, and (χ) in the sintered ore can be calculated.

Regarding the porosity, a melt is generated during sintering and this melt enters the voids, so the voids in the sintered ore are reduced compared to when the sintering raw material is charged. The porosity at the time of raw material charging can be calculated from the charging ff1 (volume 9 weight) and the true specific gravity of the raw material, but in order to estimate the porosity of the sintered ore after sintering, it is necessary to calculate the porosity based on the melt generation during sintering. It is necessary to quantify the amount of void reduction.

FIG. 7 shows an outline of the apparatus used by the present inventors to actually measure the porosity. This device heats a standard sample 11 and a test sample 12 placed inside an electric furnace 10 while applying a constant load, and compares and measures the amount of void reduction due to temperature rise. Support tube that holds down from above, 14
15 is a detection rod, 15 is a micrometer, 16 is a balance weight, 17 is a minute weight, 18 is a core, and 19 is a differential transformer field.

Figure 8 shows the SiO□
The graph shows the results of measuring the amount of void reduction at each temperature by blending silica sand and limestone so that basicity = 5.5% and basicity = 1.6. As shown in FIG. 8, the amount of void reduction with sintering temperature varies between brands depending on the origin of the ore, such as the density of the ore and differences in contained components, but shows a constant value for each brand. therefore.

When blending various ores, the amount of void reduction during sintering can be calculated by adding weights according to the blending ratio of the two ore brands, and the amount of void reduction during sintering can be calculated by combining the porosity at the time of raw material charging and the amount of void reduction during sintering. From this, the porosity of the sintered ore can be estimated.

The maximum temperature during sintering is estimated as shown in Figure 9.
A certain correlation is observed between the particle size of the sintered raw materials and the particle size during mixing and granulation. Therefore, as described above, since the pseudo-i particle size can be calculated from the blending ratio of the sintering raw materials and the moisture content, the maximum temperature during sintering can be estimated from this pseudo-particle size.

From the above, for Ill, c, f, (χ) and p, O (
χ) can be further predicted using the blending ratio and the porosity of the sintered ore, which is determined using the maximum temperature during sintering calculated from the moisture value during mixing and granulation.

Example 1 The RDI and RI of the sintered ore that would be obtained by sintering the sintered raw materials with the blending ratio shown in Table 1 after granulating them with a moisture content of 6.0% were predicted, and the RDI and R of the sintered ore obtained by
Compare with the actual measurement value of 1.

Table 1 Old: Each m-hydrated moisture value (%) of coke The saturated moisture value of the sintering raw material is determined by formula (6) using the weighted average using the saturated moisture value and blending ratio of each brand determined in advance. When calculated according to the following, 12.80% is obtained.

Saturated moisture value of sintering raw material = =Σ-4-M1 x 0.01 = 12.80
...(6) Therefore, when calculating the value of a in formulas (1) and (2) of the main text from this saturated moisture value, -
It becomes 0.4.

Also, the value of X is 180.6. Therefore, (1
) The proportion (χ) in which the -0.25 mm portion of the sintered raw material becomes adhered powder by mixing and granulation is 91.20%.

The proportion of the 0.25 to 0.5 mm portion of the sintered raw material according to (2) that becomes adhered powder by mixing and granulation is 49.14. It is calculated as %.

The particle size structure (true particle size) before granulation with the blending ratio shown in Table 1 was obtained by measurement, and is as shown in Table 2. Since the proportion of adhering powder due to mixed granulation is known, the part obtained by excluding the -0.25 mm and 0.25 to 0.5 mm adhering parts from the true particle size in Table 2 becomes the core particle, and therefore, the core particle The particle size structure of can be expressed as shown in Table 3.

Then, the harmonic mean particle diameter of the core particles is given by the following equation (7): 1
．． It is found to be 116mm.

Table 2 (Particle size distribution before granulation) Table 3 (Particle size distribution of core particles) Now, if 100g of sintering raw material is mixed and granulated with 6.0% moisture, the amount of adhesion at the -0.5mm portion The surface area of the core particle is 2 from the following equations (8) and (9), respectively.
It can be calculated as 4.3g and 1017.7cm2.

-Amount of adhesion at 0.5mm portion = 8.9 x O,492+ 21.8 x O,9
12 = 24.3 (g) (8) Surface area of core particle - rc d2n' = 1o17.7 cm2 (9 squares, n (number) = 6W/(πd1ρ).

W (weight) = 100-24.3. ρ (specific gravity')
= 3.9°d (particle size) = 0.1116cm
It is.

Therefore, the adhesion amount per unit area is 24.3/1017.7 = 0.023 g/cm", and from equation (4) in the main text, the pseudo particle size after granulation is 1.11
It can be calculated as 6 + 0.43 = 1.546 mm,
Using this pseudo particle size, +11(
10°C holding time is approximately 1.52 minutes, maximum temperature is 126 (
Ic and IIn can be determined.

On the other hand, A 1 of the melted part when the sintering raw materials in Table 1 are sintered
The zox/SiO□ ratio was 0.293 according to analysis.

To this melting part 7! zO:+/5i02 ratio and the above +1
The RDI is calculated as 32.96 using the first-order 00 equation based on the 100°C holding time.

RDI = (^2□O:+/SiO□) X 27.
7 + 27.0 + 2.9

First, c, f, (χ) and ρ, (χ) of sintered ore are estimated using the 00 formula and the αδ formula.

c, f, (χ) = a Xo, 458 + b Xo
, 346 + c Xo, 341 + d xo, 287
+ e Xo, 222 ... αυp, r, (χ
) = a Xo, 038 + b
Xo, 044 + c Xo, 032+
d xo, 117 + e xo, 211 --
(However, aJ + C + d + 8 is the ratio of each brand of iron ore, which is the main raw material, to the main raw material.

As mentioned above, the maximum temperature of the sintering raw material is 126
Since it is estimated to be 0'c, a, b, c, d, e of formula 09
When the amount of void reduction is calculated from the relationship between the sintering temperature and the amount of void reduction shown in FIG. 8 using the value of , the amount of void reduction is 5.21%. On the other hand, the porosity when charging the sintering raw material was actually measured to be 55.
It was 5%. Therefore, the porosity of sintered ore is 50.3
It can be estimated that %.

Therefore, in equation (5), c, f, (χ) = 32.5
67, p, r, (χ)-7,864, porosity = 5
By substituting 0.3% IN = 67.79%
The predicted value is obtained.

When we actually produced sintered ore and measured the RDI and III of the obtained finished sintered ore, we found that Il[actual value of lI -33,
4%, and the actual value of R1 was 68.2%.

Example 2 The same procedure as in Example 1 was repeated except that the blending conditions of the sintering raw materials and the moisture value during granulation were varied to obtain RDr and RI.
Calculate the predicted value of , and calculate the ROT and l? of the obtained sintered ore.
The actual value of I was measured. These predicted values and actual measured values are shown in FIGS. 10 and 11. As is clear from these results, the predicted values are in very good agreement with the actual values, and therefore, according to the present invention, feedforward is performed using the blending ratio of sintering raw materials and the moisture value during granulation as manipulated variables. It can be seen that a sintered ore product having the target R[)I value and R1 value can be manufactured by the control.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of the sintering pot device used in the test of the method of the present invention, Figure 2 is a relationship between +1100°C holding time and low temperature reduction index (RDI), and Figure 3 is a diagram of the relationship between iron ore A diagram showing the melting ratio during sintering for each brand particle size, Figure 4 shows the melting part A j
! go3/5iOz ratio and low temperature reduction pulverization index (RDI)
Figure 5 is a diagram showing the relationship between the grain size of the sintered raw material during granulation and +1100°C storage/waiting time, and Figure 6 is a diagram showing the relationship between the grain size during sintering raw material granulation and +1100°C holding/waiting time. c for each brand when
A diagram showing f, (χ) and p, r, (χ), Figure 7 is a 1a18 cross-sectional view of a thermomechanical analyzer that measures the amount of void reduction during sintering, and Figure 8 is a diagram showing the difference between each brand of iron ore. Figure 9 shows the relationship between the sintering temperature and the amount of void reduction; Figure 9 shows the relationship between the pseudo grain size and the maximum temperature during sintering; Figure 1O shows the relationship between the predicted RDI value and the measured 1101 value; Figure 11 shows the relationship between the predicted RDI value and the measured 1101 value. is a relationship diagram between the predicted R1 value and the actually measured III value.

Claims (2)

[Claims] (1) Load the sintering raw material into the specified sintering machine, and sinter the iron ore while maintaining the operating conditions of the sintering machine, such as pallet speed, suction air volume, and sintering raw material loading layer thickness, within the set value range. When producing ore, the pseudo grain size after granulation is calculated from the blending ratio of the sintering raw materials and the moisture content during granulation, the high temperature holding time during sintering is predicted from this pseudo particle size, and the sintering Al_2O_3/S in the melted part during sintering based on the blending ratio of sintering raw materials and chemical composition
Determine the iO_2 ratio and calculate the high temperature holding time and Al_2O_3/
Predicting the low temperature reduction powdering index of sintered ore from the SiO_2 ratio,
A method for producing sintered ore, which comprises adjusting the blending ratio of sintering raw materials and/or the water content during granulation so that the predicted value of the low-temperature reduction powdering index approaches a target value. (2) Load the sintering raw material into the specified sintering machine, and sinter the iron ore while maintaining the operating conditions of the sintering machine, such as pallet speed, suction air volume, and sintering raw material loading layer thickness, within the set value range. When producing ore, the pseudo grain size after granulation is calculated from the blending ratio of the sintering raw materials and the moisture content during granulation, and the maximum temperature during sintering is calculated from this pseudo grain size. Predict the porosity after sintering from the relationship between and the amount of porosity reduction during sintering, and
Calculate the area ratio of the calcium ferrite phase and the area ratio of primary hematite in the sintered ore mineral from the blending ratio of the sintered raw materials, and calculate the porosity, the area ratio of the calcium ferrite phase and the area of primary hematite in the sintered ore mineral. Sintering characterized by predicting the reduction rate of sintered ore from the ratio, and adjusting the blending ratio of sintering raw materials and/or the water content during granulation so that the predicted value of the reduction rate approaches the target value. Method of producing ore.