JPS6221054B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing sintered ore for iron manufacturing. Sintered ore is widely used as a raw material for blast furnaces for iron manufacturing. Criteria for determining the quality of sintered ore include chemical composition, particle size distribution, cold strength, reduction pulverizability, etc. These are extremely important factors when operating a blast furnace, so they are constantly managed. Sintered ore is manufactured by melting fine ore and adhesively bonding it together as a bond. Therefore, the room temperature strength of the sintered ore increases as the number of bond bonds increases (that is, the amount of unmelted residue decreases). On the other hand, the main cause of reduction powdering is hematite that has been once melted and solidified (hereinafter referred to as secondary hematite).
It is determined by the amount of
The amount of secondary hematite increases, which worsens reduction powdering properties. Furthermore, in order to melt a large amount, it is necessary to take a longer firing time or to increase fuel consumption. If the amount of melting is small, the cold strength will decrease. These trends are shown in Figure 1. In reality, an appropriate melting rate is determined from various viewpoints such as quality of sintered ore, productivity, fuel consumption rate, etc. (for example, the shaded range in FIG. 1). Here, the melting rate will be described in detail later, but is generally defined as the volume ratio in the sintered cake of something that has a history of melting during the sintered ore manufacturing process. In the production of sintered ore, the raw materials used include a variety of miscellaneous ores, and their melting properties vary, so even under the same operating conditions, if the raw material composition changes, the melting rate will vary. In the conventional blending of raw material ores, measuring the melting rate requires a large amount of man-hours, so quality tests are conducted on directly manufactured products without knowing the melting rate, and the blending is changed until a satisfactory quality is obtained. I had to repeat it. Therefore, it takes a lot of time to find the appropriate raw material blending conditions.
This resulted in unnecessary mixing of raw materials and production of sintered ore. The purpose of the present invention is to calculate and estimate the melting rate from various physical property values of the raw ore, set the blending ratio of the raw ore in advance based on this, eliminate wasteful production of sintered ore, and improve the quality of the sintered ore. The aim is to stabilize the energy consumption and reduce various basic units. The method of the present invention is based on the high-temperature particle porosity, particle size distribution, and chemical composition of various raw material ores that have been measured in advance, the planned volume ratio of each ore in the mixed raw material containing various raw material ores, and the firing time. The melting rate of the blended raw material is calculated from the ignition furnace energy consumption unit and the fuel addition rate, and the volume blending rate of the raw material ore is finally determined so that the calculated value becomes the target melting rate. It is said that In the production of sintered ore, a wide variety of raw material ores are used, but the melting properties of these raw materials are all different and exhibit different values even under the same temperature history. As a result of experiments, the present inventors have found that during the production of sintered ore, the melting phenomenon of raw material particles occurs when the temperature exceeds 1100°C, Fe ₂ O ₃ and CaO in the raw material ore react, and calcium and
It was discovered that this is a reaction in which ferrite is formed, an initial melt is created, and the melt progresses so that the melt erodes from the outer periphery of the ore particles inward. Therefore, the melting rate Q is the cumulative value of this melting reaction, and is determined by the time t for maintaining the temperature necessary to maintain the melting reaction (hereinafter referred to as reaction time), the raw material particle size D, and the melting rate. It is expressed by the following equations (1) and (2) depending on the linear melting velocity V. where, j: Index indicating various ore brands of raw materials i: Index indicating particle size range of particle size distribution Qj: Melting rate of ore brand j (excluding pores and voids) QT: Melting rate of blended raw material (sintered ore) ( (excluding pores and voids) t: Reaction time (time for keeping the temperature in the bed above 1100°C) Vj: Linear melting velocity in ore brand j Di: Representative particle diameter in particle size range i Wij: Volume in particle size range i of ore brand j Rate Aj: Volumetric ratio of ore brand j in the blended raw materials The reason why the melting rate varies even with the same reaction time due to differences in various ores is that the particle size distribution differs depending on the raw material ore, and the linear melting speed differs. It's for a reason. This linear melting velocity can be determined for each brand of ore through basic melting experiments. In this melting experiment, a calcium ferrite melt was created in a crucible, a measurement sample was immersed in it according to the reaction time, and the melting linear velocity was determined by measuring the erosion length. An example of the experimental results is shown in Table 1.

[Table] The present inventors have found that the melting linear velocity can be estimated by the following equation (3) from the results of melting experiments and the physical properties of the raw ore. Melting linear velocity is
Particle porosity immediately before melting reaction excluding high-temperature decomposition vaporized content in ore particles (hereinafter referred to as high-temperature particle porosity)
There is a close correlation with the chemical composition. It was confirmed that there was a good correlation between the melting line velocity calculated by equation (3) and the measured value, as shown in Figure 2. Vj = ki (E) j + k ₂ (Al ₂ O ₃ ) j + k ₃ (SiO ₂ ) j + k ₄ (CaO) j + k ₅ (FeO) j + k ₆ (MgO) j + k ₇ (Na ₂ O) j + k ₈ (K ₂ O) j + k ₉ (TiO ₂ ) + k ₁₀ ... (3) where, k ₁ ~ _{k 10} : constant (E) j: high temperature particle porosity of ore brand j (Al ₂ O ₃ ) j ~ (TiO ₂ ) j: ore Concentration of each chemical component in brand j Conventionally, it took a lot of man-hours to actually measure the high-temperature particle porosity, but as a result of experiments, the present inventors found that the high-temperature particle porosity E is the particle porosity at room temperature. It was confirmed that Eo can be accurately calculated using the following equation (4) from the content of crystal water CW and carbonate MCO ₃ , which are the main components of high-temperature vaporization in the ore (Section 3).
(see figure). (E) j=1-{1-C ₁ (CW) j-C ₂ (MCO ₃ )
j} × { ₁ − (Eo) j: room temperature particle porosity in ore brand j C ₁ , C ₂ : constant The reaction time t is determined by the time during which the temperature history in the layer is maintained at 1100° C. or higher. The temperature history in the bed is determined by the operating conditions and the amount of fuel added, so it can be known in advance through operational tests and measurements. Further, the reaction time can be generally expressed as a function of firing time, ignition furnace energy consumption rate, and fuel addition rate, and an example of the relationship is shown in FIG. 4. As described above, by substituting the reaction time, raw material particle size distribution, and various physical properties of the raw material ore into equations (1) to (4), the melting rate of the blended raw materials can be calculated, and this calculated value provides the appropriate quality. The volume ratio of the raw material ore can be finally determined so as to match the target value. Examples Examples were carried out under the conditions shown in Table 2.

[Table] The reaction time t is given as a function of firing time, ignition furnace energy consumption rate, and fuel addition rate, and in this example, the reaction time corresponding to the data in Table 2 is calculated from each standard curve in FIG. The average time was determined to be 6.4 minutes. The appropriate melting rate was set at 80% from Figure 1. Table 3 shows the results of calculating the melting rate during firing of simple ore from the physical property values of various raw material ore brands. Based on this result, Table 4 shows examples of combinations that result in a melting rate of 80% during firing of the mixed raw materials. Fourth
Table 5 shows the results of actual operation for one month using the raw materials shown in the table, in comparison with the conventional method. Fifth
From the table, it can be seen that the products produced by the method of the present invention have less variation in quality, eliminate wasteful production of sintered ore, and reduce coke consumption.

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【table】 [Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between melting rate and sintered ore quality. FIG. 2 is a graph showing the correlation between actually measured values and calculated values of linear melting velocity. FIG. 3 is a graph showing the correlation between measured values and calculated values of high-temperature particle porosity. FIG. 4 is a graph showing the relationship between reaction time and various conditions.

Claims (1)

[Claims] 1 The high-temperature particle porosity, particle size distribution, and chemical composition of various raw material ores measured in advance, the planned volume ratio of each ore in the raw material blended with various raw material ores, firing time, and ignition furnace energy source. The melting rate of the mixed raw material is calculated from the unit and the fuel addition rate, and the volume blending rate of the raw material ore is finally determined so that the calculated value becomes the target melting rate. Production method.