JPS6124456B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sintering operation 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 produced 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 once been 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, a variety of miscellaneous ores are used as raw materials, and their melting properties vary, so even under the same operating conditions, if the raw material composition is changed, 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 predict the melting rate in the sintering furnace in advance from the physical property values of the sintering raw material and the measured firing rate, set the firing rate so that this becomes the target value, and eliminate unnecessary sintered ore. The aim is to eliminate manufacturing, stabilize the quality of sintered ore, and reduce various basic units. The operating method of the present invention calculates the melting rate of the blended raw materials from the actual value of the sintering rate and the physical properties of each raw material ore calculated in advance in the process of manufacturing sintered ore, and adjusts the melting rate so that the calculated value becomes the target melting rate. It is characterized by controlling the firing speed. 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 phenomenon of melting of ore particles occurs when the temperature exceeds 1100℃, CaO in the raw material reacts, forms calcium ferrite, and creates an initial molten liquid. It was discovered that this reaction progresses melting so that the molten liquid gradually erodes from the outer periphery of the ore particles toward the inside. Therefore, the holding time t at 100° C. or higher and the melting rate Q of the blended raw materials are expressed by the following equation (1). moreover,
The melting rate of the blended raw materials when held at 1100℃ or higher for 6 minutes is the melting rate qj of each single ore brand.
(1100℃ or more for 6 minutes) is expressed as equation (2) by taking a weighted average. Q=・(t/6)n...(1) However, t: Holding time over 1100℃ (minutes) n: Constant j: Index indicating various brands of raw materials qj: Melt rate of ore brand j (excluding pores and voids) wj: Melting rate of ore brand j in the blended raw materials Volumetric ratio The melting rate qj of each single ore brand when held at 1100°C or higher for 6 minutes can be experimentally determined in the laboratory when raw materials are received. An example of the measurement results is shown in the first section.
Shown in the table.

[Table] The reason why the measured melting rate was determined when the holding time at 1100°C or higher was 6 minutes was because the average holding time at 1100°C or higher was 6 minutes based on the temperature history in the layer during sintering operation. Because there is. Hereinafter, the melting rate of a certain ore brand when the holding time at 1100°C or higher is 6 minutes is referred to as the melting index of the ore brand. By suitably combining different melting indexes, the melting rate of the compounded raw materials can be varied. In this case, the melting rate of the raw materials can be changed by changing the brand of ore or by adjusting the particle size of the same brand. For example, in the case of SF Hammersley, when the average diameter is 3, 2, and 1 mm, the melting index is
79.0, 84.0, 98.0Vo1%. Now, this holding time t has a close relationship with the firing speed v, and this relationship is shown in FIG. 2. Also, when expressed as an equation, it is shown as equation (3). Figure 2 shows the firing speed v
The holding time t at 1100°C or higher was investigated while varying the temperature. t=av ² +bv+c...(3) where, v: Firing speed (mm/min) a, b, c: constants There are various ways to measure the firing speed v, but the simplest method is as shown in Figure 3. As shown in , in the sintering machine 1, sintering is considered to be completed when the temperature of the sintering exhaust gas in the window box 3a at the front stage reaches its peak, the sintering time (T) is measured, and the amount of the raw materials mixed at this time is determined. v=H/T can be determined from the layer height (H). The firing speed v is determined by the sintering machine 1 as shown in FIG.
In this step, the rotation speed of the firing blower 2, the opening degree of the damper 31 of the wind box 3, the height of the raw material layer in the pallet 4, the raw material packing density, the amount of moisture added to the raw material granulation mixer 5, the granulation degree, etc. are adjusted. controlled by FIG. 5 shows an example of the effect on the firing rate v when these factors are changed. The melting rate is calculated by substituting the melting index qj for each ore brand, its volume mixing ratio wj, and firing speed v found in the above manner into equations (1) to (3), The raw material blend or firing rate is controlled to match the melting rate to the target quality. <Example> The operating method of the present invention was carried out after DL type sintering.
Using ore brands A to H having different melting indexes shown in Table 2, a DL type sintering machine was controlled so that the melting rate of the blended raw materials was constant.

[Table] In the DL type sintering machine 1 shown in FIG. 4, each time the blending ratio of the raw material ore is changed, the melting rate of the blended raw materials will change if the firing rate is constant. As described above, the firing speed v is determined by detecting the peak time of the sintering exhaust gas temperature (that is, the sintering time T) by the thermometer 32 installed in the window box 3, and by detecting the peak time of the sintering exhaust gas temperature (that is, the sintering time T). It was calculated by detecting the height H of the raw material layer in the pallet 4 from the set height (v=H/T). Calculate the firing speed at which the melting rate Q of the mixed raw materials is constant from the set volume blending ratio of the raw material ores and the melting index of each raw material ore at that time, and set the rotation speed of the firing blower 2 to maintain this firing speed. The operation was carried out by adjusting the opening degree of the dumper 31 of the wind box 3, the set height of the cut-off plate 6, and the amount of water injected from the mixer water injection pipe 51 to the raw material granulation mixer 5 (Fig. 6). For reference and conversely, in order to ensure the production volume, the volume blending ratio of the raw material ore is set so that the firing speed v is constant and the melting index q of the blended raw material is constant.
The operation was carried out by adjusting wj (Fig. 7). Table 3 shows comparative examples between examples based on the method of the present invention and the conventional method. As can be seen from Table 3, according to the method of the present invention, the quality of the sintered ore was stabilized, and at the same time, it was possible to improve the quality of the sintered ore and reduce the coke consumption rate.

【table】 [Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the melting rate and the quality of sintered ore. Figure 2 shows the firing speed and temperature inside the molten layer, 1100℃.
The above is a graph showing the relationship with the retention time. FIG. 3 is a graph showing the sintering exhaust gas temperature in each wind box. Figure 4 shows the method of the present invention being applied.
Schematic diagram of the DL type sintering machine. FIG. 5 is a graph showing an example of the tendency of the relationship between firing speed and each condition. 6th
The figure is a graph explaining an example when the firing rate is controlled based on the method of the present invention. FIG. 7 is a graph illustrating an example when the blending ratio of blended raw materials is controlled for reference. 1: Sintering machine, 2: Sintering blower, 3: Window
box, 4: pallet, 5: raw material granulation mixer,
6: Cut-off plate, 31: Damper, 3
2: Thermometer, 51: Water injection pipe.

Claims (1)

[Claims] 1. In the process of manufacturing sintered ore, the melting rate of the blended raw materials is calculated from the measured firing rate and the various physical properties of each raw material ore calculated in advance, and the firing rate is adjusted so that the calculated value becomes the target value. A firing operation method characterized by: