JPH0733532B2 - Blast furnace bottom erosion prevention method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing erosion of the bottom of a blast furnace, and more specifically, it uses only a tap hole whose slag ratio is equal to or higher than the average slag ratio to carry out the tap slag work, and thus The present invention relates to a method for preventing erosion of the bottom of a blast furnace for preventing erosion of refractory materials.

[0002]

2. Description of the Related Art The life of a blast furnace has exceeded 10 years due to advances in blast furnace repair technology and intermediate repair technology. Under these circumstances, it is the erosion state of the bottom of the furnace that determines the life of the blast furnace.

Conventionally, as a means for preventing erosion of the bottom of a furnace, a Ti source is charged into the furnace to generate titanium bear on the bottom of the furnace, and the fact that the titanium bear does not flow easily protects the bottom of the furnace. (For example, JP-A-50-12040
(See Japanese Patent Publication No. 5). However, in this method, a considerable amount of the charged Ti source is taken into the pig iron and the slag, and the quality of the hot metal and the quality of the slag are changed. Further, it is often attempted in actual operation to increase the amount of cooling water in the bottom of the furnace to prevent bottom erosion by increasing the amount of cooling. However, the refractory at the bottom of the blast furnace during operation has a thickness of 3 to 4 m, and the heat transfer of this refractory is rate-determining.

When the temperature of the bottom of the furnace rises abnormally, a measure of rest is taken as a last resort. The effect is great,
The temperature of the bottom of the hearth is also lowered to prevent bottom erosion. However, since the operation stopped during that time, nothing was produced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to effectively prevent the bottom corrosion of the blast furnace by keeping the blast furnace operation and without changing the quality of the produced pig iron and slag. The purpose is to propose a method.

[0006]

That is, according to the method of the present invention, when operating a blast furnace having a plurality of tap holes, the temperature of a thermometer attached to the bottom brick or the rate of temperature rise is above a specified level. When the slag ratio for each tap is less than the average slag ratio, only the taps are used for subsequent tapping, and the temperature of the thermometer attached to the bottom brick is below the specified level. Moreover, when the rate of temperature rise is below a specified level, another tap hole is used to carry out tapping slag.

[0007]

The structure of the present invention and its operation will be described below with reference to the drawings.

FIG. 1 is an explanatory view of a model experimental apparatus corresponding to the bottom erosion, FIG. 2 is an explanatory view of a filling structure of a blast furnace hearth part, and FIG. 3 is a model experiment corresponding to the bottom bottom erosion. FIG. 4 is an explanatory diagram of the apparatus, and FIG. 4 is a graph showing an operation transition when the present invention is carried out. Reference numeral 1 is a partition plate (impermeable layer), 2 is liquid 1 (similar slag), 3 is liquid 2 (similar hot metal), 4 is filled particles, 5 is a valve (left tap hole), and 5'is a valve. (Right tap), 6 is a tank for supplying the liquid 1 to the experimental apparatus, 7 is a tank for supplying the liquid 2 to the experimental apparatus, 8 is a liquid supply pipe, 9 is a non-permeable layer, and 10 is a tap. .

The present inventors have found that CAMP-ISIJ. 2 (1
989). As described in P91, it was found that a refractory layer of molten pig iron was present at the bottom of the blast furnace. The following is shown there. As shown in Fig. 2, when there is a difficult-to-permeable layer covering the furnace bottom, the furnace bottom temperature is low and there is no bottom erosion. If the difficult-to-permeable layer is partially or completely removed, hot metal flows into the furnace bottom. The bottom erosion progresses as the bottom temperature rises.

Further research has revealed the following. It is conceivable that the peaks of the poorly permeable layer in FIG. 2 are not always located at the center and may be biased. Assuming such a case, we conducted an experiment using a model experiment device in the laboratory and found that the slag ratio (= amount of slag / amount of slag) at each tap was found to be uneven if the center of the mountain in the impervious layer was biased. ), There is a deviation from the tap hole. Further, when the refractory layer is biased to the left as shown in FIG. 3, when alternate tapping is performed, the slag ratio of the left taphole (A) is lower than the average slag value, and the right taphole ( The slag ratio of B) becomes high. As shown in Fig. 1, when a part of the impervious layer disappears, that is, this is the period when the furnace bottom temperature rises and the furnace bottom is eroding in the actual machine, but in this case also the slag ratio is The left is low and the right is high. At this time, the amount of liquid flowing into the bottom of the furnace was measured, and it was found that the amount of tapping from the right was smaller than the amount of tapping from the example. In addition, when some suspension was mixed in the liquid and an experiment was performed, when tapping from the tap hole on the right, the suspension agglomerated at the break of the difficult-to-permeable layer below the tap hole, causing clogging. Raised and no liquid flowed into the bottom of the furnace. In the case of tapping from the opposite taphole, this phenomenon was not observed. This difference comes from the difference in the inflow speed of the liquid into the furnace bottom, and the lower the inflow speed of the liquid into the furnace bottom is, the more easily clogging occurs.

Considering the above experimental results, the following can be said in the case of an actual machine. When the deviation from the taphole appears,
It shows that the impermeable layer is offset from the center. Moreover, if the furnace bottom temperature rises in that state,
That means that the part of the impervious layer disappears as shown in FIG. 1 and the liquid enters the furnace bottom and begins to erode the furnace bottom. Therefore, if tapping from the taphole with the larger slag ratio at that time is considered to be less intrusion of hot metal to the furnace bottom and less erosion of the furnace bottom than tapping from the taphole that is not so large. In addition, if the iron is tapped only at the tap hole for a long period of time, a suspension of the quiche graphite or coke ash, which is a constituent material of the refractory layer generated in the hearth, in the melt is Repair cuts and stop the flow of melt to the bottom of the furnace. Therefore, the erosion of the bottom of the furnace stops and the temperature of the bottom of the furnace also decreases.

[0012]

EXAMPLES The present invention was carried out in a blast furnace having an internal volume of 2584 m ³ and two tap holes. Table 1 shows the main operating specifications at this time.

[0013]

[Table 1]

The operation history is shown in FIG. The period A in FIG. 4 is a period corresponding to a comparative example in which the present invention is not carried out, and is a period in which alternate tapping is continued even if the furnace bottom temperature rises. The brick thickness estimated from the furnace bottom two-point thermometer is greatly reduced. Therefore, the present invention is implemented from the period B. In this blast furnace, when the bottom temperature exceeds 220 ° C, or when the rate of rise in the bottom temperature is 5 ° C / day or more, the tap hole deviation is judged, and the slag ratio exceeds the average slag ratio. So I decided to tap on one side. Also,
When the furnace bottom temperature was 225 ° C or less and the rate of rise of the furnace bottom temperature was 0.5 ° C / day or less, it was decided to tap the other tap hole. After using this method, the brick thickness estimated from the furnace bottom two-point thermometer did not decrease. Regarding the quality of the hot metal and slag, not to mention Ti, the chemical composition and the hot metal temperature did not change. Also, there was no rest air due to abnormal rise in bottom temperature.

Since the boundary value of the furnace bottom temperature is determined by the installation position of the thermometer, the brick material, etc., the value differs for each blast furnace.

[0016]

By carrying out the present invention, it is possible to prevent the erosion of the furnace bottom refractory while maintaining the amount of tapping metal and without changing the quality of the hot metal and slag.

[Brief description of drawings]

FIG. 1 is an explanatory view of a model experiment device corresponding to a bottom erosion.

FIG. 2 is an explanatory diagram of a filling structure of a hearth of a blast furnace.

FIG. 3 is an explanatory diagram of a model experimental device corresponding to a case where a furnace bottom does not erode.

FIG. 4 is a graph showing a transition of operation when the present invention is carried out.

[Explanation of symbols]

 1 Partition plate (hardly permeable layer) 2 Liquid 1 (similar slag) 3 Liquid 2 (similar hot metal) 4 Filled particles 5 Valve (left iron tap) 5'valve (right iron tap) 6 Liquid for experimental equipment 1 supply tank 7 supply tank for liquid 2 to experimental equipment 8 liquid supply pipe 9 impermeable layer 10 taphole

Claims (1)

[Claims] 1. When operating a blast furnace equipped with a plurality of tap holes, when the temperature of a thermometer attached to the bottom brick or the rate of temperature rise exceeds a specified level, The slag ratio (amount of slag / amount of slag) is higher than the average slag ratio, only subsequent tap slag is carried out, and the temperature of the thermometer attached to the bottom brick is below the specified level. A method for preventing erosion of the bottom of a blast furnace, characterized in that when the rate of temperature rise falls below a specified level, another tap hole is used to carry out tap slag.