JPS62116727A - Method for controlling pelletization of sintering raw material - Google Patents

Abstract

PURPOSE:To quickly find out exact pelletization conditions by solving the material balance equation into which a pelletization speed function is incorporated for each of grain sizes, estimating the change of the grain size distribution of pelletized particles with time and adjusting the conditions for pelletizing raw materials and the conditions for operating pelletization. CONSTITUTION:The pelletization speed function to express the propability at which the particles meeting each other in a pelletizing machine combine each other is incorporated into the material balance equation to express the grain size distribution according to the progression of the pelletization. The equation is solved for each of the grain sizes to estimate the change of the grain size distribution with time according to the growth of the pelletized particles. The grain size distribution after the execution of the prescribed pelletization stage is determined from the estimated value. The conditions for the pelletizing raw materials and the conditions for operating the pelletization are adequate if the grain size distribution obtd. in such a manner coincides with the standard value. The conditions forthe pelletizing raw materials and the conditions for operating the pelletization are returned to a setting stage and the new conditions are set when the grain size distribution does not coincide with the standard value. The similar operations are thereafter carried out and the operations are repeated until the calculated value coinciding with the target grain size distribution is obtd.

Description

[Detailed description of the invention]

[Field of Application in Industry A] The present invention is directed to powdered ore f?, which is a raw material for producing sintered steel.
: Regarding the granulation control method during granulation, in detail, the raw material conditions such as the brand and composition of the sintering raw materials are influenced by the granulation operation conditions. This article relates to a sintering raw material granulation SLJ control method that can accurately determine Pi granulation raw material conditions or granulation operation conditions so as to obtain granules with the target particle size composition. [Prior art] Iron ore used as an iron source for blast furnace steelmaking needs to be agglomerated to improve ventilation per m1qI in order to increase and stabilize blast furnace operating efficiency. A typical method for this purpose is the sintering method.In other words, the sintering method is used to reduce the particle size (generally speaking, it is desirable that the total particle size is 8 am or less and 125 μm or less is less than 10%). ) is a method of burning and solidifying iron ore into a lump, and the granulation process that takes place prior to sintering is considered to be an important process that determines the quality of the sintered ore.In this granulation process, fine powder is Binder and other additives (limestone, quicklime, coke powder, return ore, etc.) are added to granular iron ore, and the humidity is controlled and granulated using a drum mixer, pan pelletizer, etc., and the particle size is adjusted to the specified size. During the sintering process, the granulation efficiency and properties of the granules (particularly the degree of pulverization during sintering; the properties of the granules are also closely related to the properties of the sintered substances). ) will vary significantly depending on the brand of raw material ore, the granulation conditions such as the amount of binder, or the granulation operation conditions.Therefore, it is possible to efficiently produce granules with desired physical properties. In order to obtain this, it is necessary to accurately understand the granulation property (easiness of granulation) of the raw material ore, and to mix additives such as binders that are adjusted according to the granulation property.
2. Furthermore, it is necessary to appropriately control the granulation operation conditions related to the operation of the granulator. As one of the above-mentioned granulation property evaluation methods, the method disclosed in "3rd Edition Iron and Steel Handbook", Volume 1 @, Refined Iron and Steel Manufacturing, pp. 3484-86 (published by Maruzen Co., Ltd.) is used.

[A method of evaluating by pseudo-graining index is known, and it has been confirmed that this pseudo-graining index has a high correlation with the air permeability of the sintered material. [Problems to be solved by the invention] However, these methods for evaluating granulation properties evaluate granulation properties based on data obtained by actually conducting granulation tests. The method of determining the basic physical properties of the iron ore itself and evaluating the granulation properties based on that is not effective, so if the brand of iron ore raw material changes or the raw material blending ratio is changed, a granulation test should be carried out each time. Line 12: By repeating trial and error, the optimum granulation conditions (including granulation raw material conditions such as water content and granulation operation conditions) according to the granulation properties of the granulated i-material powder must be set. figure,
A great deal of time and effort was spent on setting the granulation conditions. The present invention was made in consideration of these circumstances, and
The purpose is to be able to accurately estimate the granulation properties of the granulation raw material powder based on its basic physical properties, and to properly set granulation conditions based on the estimated granulation properties. The purpose of this study is to establish a technology that enables granulation control, and provides a granulation control method that can quickly find accurate granulation conditions without conducting preliminary granulation experiments. Means for Solving Problem E] The granulation control method according to the present invention combines particles encountered in a granulator during a mass balance equation that expresses a particle size distribution that changes as granulation progresses. By including the granulation rate interval representing the probability and solving the above mass balance equation for each particle size, the particle size distribution of the granulated particles under pre-given granulation raw material conditions and granulation operation conditions can be determined. The gist of this method is to estimate the temporal change in the granulation material and adjust the granulation raw material conditions or granulation operation conditions so as to obtain the target particle size distribution. 1 Effect] The present invention is directed to the progress of granulation of raw material powder (growth of pseudo particles)
The granulation rate function, which represents the probability that particles encountered in the granulator will coalesce, is included in the mass balance equation that represents the change in particle size due to granulation. Since it is determined by the difference between the force and the drag force, by solving the above material balance equation for each particle size, we can determine the relationship between the 5 granulation conditions and granulation growth, that is, the conditions on the granulation raw material side (for example, the raw material The particle size distribution of the granulated product when the brand and blending ratio, moisture content, binder amount, etc.) and the conditions of the granulation operation (for example, the configuration and specifications of the granulator, and the fit conditions) are specified. By determining the temporal change in granulation, it is possible to determine the particle size distribution after a specific granulation time has elapsed, but as is clear from the examples below, the particle size distribution determined by calculation cannot be obtained by conducting granulation experiments. It has been confirmed that the particle size distribution corresponds well to the measured particle size distribution. Therefore, by variously changing the granulation raw material conditions and granulation operation conditions and recalculating the particle size distribution, it is possible to almost accurately know the various conditions under which a granulated product matching the target particle size distribution can be obtained. By the way, from the size X at time dt during granulation, (x
＋c! The mass balance of particles growing to x > is as follows [1
It can be expressed by one equation. ...[11 Here, x and y are the particle diameters, s (x, y) are the weight proportions of the granulation speed particles, and s (x, y) is the inside of the granulator as described above. It represents the probability that the particle bears of It is considered that it is proportional to the difference between the tensile strength (O7) of
[,0] In the [11] formula, 0 is determined by the particle size composition of the particle layer, moisture content, binder content, iron ore brand (including the unique adhesiveness and shape factor of each region), etc.
This value can be actually measured as a relative value by a tensile test or a shear test of the granulated material. Further, K and σ can be determined by performing nonlinear multiple regression analysis on a large number of granulation experiment data using the granulator. Therefore, it can be obtained by substituting the values of σ and σ into the above [+1′] formula. When s(x,, y) is incorporated into the tribute balance equation [I] as a granulation rate function and this equation is solved for each granulation, the raw material powder under the granulation raw material conditions and - granulation operation conditions can be calculated. It is possible to know the particle size distribution of granules during the granulation process. Therefore, if the granulation raw material conditions and granulation operation conditions are changed/i*u so that the particle size distribution at the time of completion of the granulation operation matches the target particle size distribution, the granulation raw material conditions are optimal to ensure the target particle size composition. and granulation operation conditions can be set. In addition, when the brand, blending ratio, etc. of the granulation raw material are determined in advance, the same calculation as above can be performed using only the granulation insertion conditions as a variable to determine the optimal granulation when using the relevant granulation raw material. Operation conditions can be determined. Figure 1 is a block diagram outlining the process of setting the granulation raw material conditions and granulation operation conditions.The first step is to set the granulation raw material conditions and granulation operation conditions (iron ore brand, initial The particle size, blending ratio, moisture content, binder fi type and amount, and the operating state of the granulator are set), and the value of σ and σ are determined according to these setting conditions. 20 values were selected based on the tensile test @ or shear test data, and these values were calculated according to the above [1
By substituting the granulation rate function into the formula [1], the granulation rate function [S(x,,y)] under the granulation raw material conditions and granulation operation conditions can be obtained. , and solving for each particle size, it is possible to estimate the change in the IT particle size distribution over time as the granules grow. Then, based on the estimated value, the particle size distribution after performing the predetermined granulation process can be determined, so if this particle size distribution matches the target particle size distribution of the granulated material, the above-mentioned granulation The raw material conditions and granulation and cutting conditions will be adjusted to suit the conditions and the process will be transferred to actual operation. On the other hand, if the calculated value of the particle size distribution does not match the target particle size distribution, return to the step of setting the granulation raw material conditions and granulation operation conditions, set new conditions, and repeat the same operation to achieve the target particle size distribution. This operation can be repeated until a matching calculated value is obtained, and when the calculated value of the particle size distribution matches the target particle size distribution, the granulation raw material and granulation operation conditions can be considered appropriate and transferred to actual operation. When setting new conditions, fix the raw material brand and blending ratio and make various changes to other conditions, and if these changes alone cannot deal with the problem, then change the raw material brand, or change the raw material brand. It is preferable to deal with this problem by increasing the amount of the compound. [Example] Using an experimental drum-type granulator with a diameter of 50 mm and an IX depth of 35011□I, ore powder collected from a blending pile at a steel mill was used as a granulation raw material. O7 and a were determined using the following method for the raw material powder. Raw material powder blending composition> Granulation raw material conditions><K, σ7. Measuring method of σ〉 σy knee 25・Gμm ore particles with moisture 5.6% 5Ca1
1.・Tensile test value when adding 5%, 1Lffg/c
m' K Pa) Nonlinear multiple regression value of granulation test data σ When incorporating into the above equation [111] and solving the physical acquisition equation for each particle size, and calculating the temporal change in particle size distribution, the results shown by the solid line in FIG. 2 were obtained. On the other hand, using the experimental drum-type granulation loss described above, an actual granulation experiment was conducted under the same conditions as above, and the granulation was completed for a specified period of time. ! i
After examining the particle distribution of the granulated product after a, we obtained the measured values shown by O2△ and square marks in Figure 2, and it was confirmed that both values agreed well with the values obtained by calculation. Ta. Also, according to the experience of the present inventors, wr, m in the granulation raw material
It has been confirmed that by blending an appropriate amount of tt ore powder, pseudo-particle formation is promoted and granulation properties are improved. , In order to clarify the appropriate amount of fine ore to be added,
The above method (however, as a raw material ore, the average particle size is 250μ
m blended jig pile ore is used, the additives are water: 5.6%, CaO: 1.5%, and the fine ore is 1250 ur++, 10 to 40% of the raw ore.
Addition 1] Furthermore, the particle size distribution of the granulated product was determined according to (the granulation time was 13 minutes). The ratio of the average particle diameter before and after granulation is calculated as the granulation index (A, 1 ==DprOd, /
Df, aed ), −2,50 μm 11
The relationship between the mixing ratio of fine ore and Ai was determined by calculation, and a granulation experiment was actually conducted to compare the results with the above calculated values. The results are shown in Figure 3.2 The calculated values obtained according to the method of the present invention and the experimental values are very similar, and in both cases,
-Highest A when 20% of 250urn @ powder is mixed.
A common result was that the i value was obtained. In addition, in Figure 4, 3F4 @ fine ore (a... soft hematite ore, b... limonite ore 2, C... hard hematite ore) is selected, and X is added according to the above method.
This figure shows the results of similarly determining the particle size structure after granulation for Q minutes. In the calculations to derive the results shown in Figure 4, differences in ore brands are treated as differences in the tensile strength of each compact, but these calculation results are based on the already known granulation characteristics of each ore. Responds well. [Effects of the Invention] The present invention is configured as described above, but in short, the granulation process is carried out based on the physical characteristics of the raw material itself and the values determined by the granulation device, operating conditions, etc. for obtaining sintered ore. The granulation efficiency and the particle size distribution of the granules can be almost accurately estimated by calculation from the substance J matrix formula of the granules. Therefore, even if the grain size distribution of the granules is predetermined, the granulation raw material conditions and granulation operation conditions can be determined based on calculations to ensure the target particle size distribution. Trial-and-error granulation experiments that were required each time the brand, blending ratio, etc. are changed can be omitted. Moreover, with the conventional method of setting appropriate granulation conditions through granulation experiments, the best granulation conditions cannot be found unless a large number of systematic granulation experiments are conducted that target various variable factors. However, in the case of the present invention, all that is required is to obtain the tensile strength data σ, which is determined by the operating conditions including the granulation device, and σ, which is roughly determined by the granulation raw material conditions. Since fluctuations in granulation speed and particle size distribution can be accurately determined through calculation, optimal granulation conditions corresponding to the brand of raw material ore can be determined extremely quickly and reliably just by using a simple calculation device. Can be set.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the process of setting conditions employed in the present invention, and FIGS. 2 to 4 are graphs showing experimental data obtained in Examples. 1 person Kobe Steel, Ltd. Figure 1 Q,,'l 0.5 1 5
101 children 17 fl 1 -25. (brn! bF'E stone $im+S) Figure 4 Moisture 5.6% 0.2 1 5
10 particle diameter (ff)

Claims (1)

[Claims] A granulation rate function that represents the probability that particles encountered in the granulator coalesce is included in the mass balance equation that expresses the particle size distribution that changes as granulation progresses, and the mass balance equation can be modified for each particle size. By solving the equation, it is possible to estimate the temporal change in the particle size distribution of the granulated particles under the pre-given granulation raw material conditions and granulation operation conditions, and adjust the granulation raw material so that the target particle size distribution is obtained. A method for controlling granulation of sintered raw materials, characterized by adjusting conditions or granulation operation conditions.