JPS5993842A - Sintering method of iron ore raw material - Google Patents

Abstract

PURPOSE:To measure directly the air permeability of a sintering raw material with a relatively simple mechanism and to control the same by detecting the air permeability with a permeability measurement device provided in the negative pressure section on the suction side for hot air of a sintering device and increasing or decreasing the amt. of the water to be added to the sintering raw material. CONSTITUTION:The raw material powder and granules supplied from a raw material hopper 5 to a kneader 6 are kneaded and humidified together with the water supplied through a flowmeter 7 and a water feed valve 8, and the mixture is sent as a sintering raw material A successively into a sintering device. The juncture 13a of a permeability measurement device 13 is connected, via a flow rate control valve 10, a pressure gauge 11, and an airflow meter 12, to a pipeline 9 for measuring gas permeability connected to the proper place of a hot air induction duct 4. A part of the material A is sampled and packed into a packing part 13b of the device 13 which is open at the top surface and has a fine meshed metallic screen 14 in the bottom. The valve 10 is controlled to maintain the specified suction pressure measured with the gauge 11 and thereafter the quantity of the air permeating the inside of the layer packed with the raw material is measured with the meter 12. A permeability index is calculted by a prescribed equation, and the calculated value and an optimum air permeability is compared, according to the difference whereof, the amt. of the water to be added to the device 6 is increased or decreased.

Description

[Detailed Description of the Invention] The present invention relates to a method for sintering iron ore raw materials, and in particular, by controlling the amount of water added to the raw material for sintering, the air permeability of the raw material is appropriately adjusted, and sintering is made as possible as possible. It relates to a method that can be carried out uniformly and efficiently.

Powdered iron ore for blast furnace charging is made by putting appropriate amounts of coke, limestone, binder, and return ore into a drum mixer, etc. together with an appropriate amount of water, mixing and conditioning the moisture, and then sintering it in a sintering device. The sintered ore is further processed through the steps of primary crushing, cooling, secondary crushing, and sieving, and is finally made into sintered ore having a diameter distribution of about 5 to 50 mm.

Here, the general sintering apparatus is a through-hole shown in FIG. 2 is supplied onto the
The overculm of the sintering device 80 passes through the ignition section 8a, the sintering section 8b, and the cooling section 8c in order and undergoes a predetermined treatment, and the culm is further processed in a crushing process (not shown) and the sieve is subjected to post-processing in a process etc. to sinter to an appropriate particle size. It becomes condensation.

That is, in the sintering process, static electricity is applied from above to below the raw material charging HA, and coke in the sintering raw material is ignited in the ignition section 3a. Then, in the sintering section 8b, the coke is ignited and burned toward the lower MiJ (141) by passing the hot air generated by the ignition combustion, and the sintering reaction progresses. 8C, where it is cooled and sent to a post-processing step (not shown).In the figure, 4 indicates a hot air induction duct.

By the way, it is well known that the permeability of the sintering raw material is extremely important for the efficient progress of the sintering reaction.
Forty-four proposals have been made to ensure optimal breathability. Factors that affect air permeability include the particle size structure of raw materials, binder rods, return ratio, amount of water added, filling rate of raw materials, etc. Among them, water content has a significant effect on air permeability. It has been confirmed that (Figure 2: graph showing the relationship between moisture content and air permeability of sintering raw materials), it is essential to control the amount of added moisture. Under these circumstances, a technique was proposed, for example, as disclosed in Japanese Patent Publication No. 17921/1983. In this method, a bypass is installed in the feed line of the sintering raw material, a part of the raw material is continuously extracted and its porosity or specific surface area is measured, and the appropriate moisture content is calculated from this measurement value and then added to the raw material. While setting the amount of added moisture, a part of the raw material is continuously extracted from the feed line, the actual moisture content of the raw material is measured, and this is compared with the set value to correct the set value, The aim is to appropriately control the air permeability of the sintering raw material by automatically controlling the amount of water added to the sintering material. This announced invention was made based on the knowledge that there is a linear relationship between the porosity of the sintering raw material and the appropriate moisture content, and is extremely effective as a means for controlling air permeability. it is conceivable that.

However, in this method, a part of the sintering raw material is extracted and once dried, the porosity and specific surface area are measured, and then the appropriate moisture content is calculated, and the actual moisture content is also measured and compared. This has the disadvantage that the control device is significantly more complex. Moreover, since it takes a considerable amount of time to dry the sintering raw material and to determine the hiU, there is a lack of quick response.

The present inventors focused on the above-mentioned circumstances, and developed a relatively simple e-
I! We have been conducting research in an effort to establish a technology that can directly measure and properly control the air permeability of sintered raw materials using wood, and that can also be sufficiently responsive to continuous operation. . The present invention was completed as a result of such research, and its configuration is such that an air permeability measuring device is connected to the negative pressure system on the hot air induction side of the sintering device through a ventilation line equipped with a pressure gauge and an airflow meter. A part of the sintering raw material is connected to the measuring device, the upper surface of the measuring device is opened to the atmosphere, and the air permeability of the sintering raw material is detected from the pressure and air volume of the airflow flowing through the wine in the direction of the negative pressure thread. The gist lies in adjusting the air permeability of the sintering raw material by increasing or decreasing the amount of water added to the sintering raw material accordingly.

The configuration and effects of the present invention will be explained below with reference to the drawings. The greatest feature of the present invention is that, as mentioned above, the air permeability control mechanism is simplified and quick response is ensured.In addition, the moisture content of the sintering raw material has the greatest effect on air permeability. By skillfully taking advantage of the fact that It also has a major feature in that it can be adjusted appropriately.

FIG. 8 is a schematic overall view showing an embodiment of the present invention, in which the raw material powder and granules supplied from the raw material hopper 5 to the kneading device 6 are
The sintering raw material A obtained by kneading and controlling the humidity together with water supplied through the flow meter 7 and the water supply valve 8 is sequentially fed into the sintering apparatus from the raw material supply section 1. In the present invention, a part of this sintering raw material A is collected and filled into an air permeability measuring device, which will be described in detail below.
The air permeability of the sintering raw material A is directly measured, and the amount of water added to the kneading device 6 is increased or decreased accordingly to adjust the air permeability to an appropriate value. That is, in the present invention, the air permeability measurement pipe line 9 is connected to an appropriate location of the hot air induction chute 16 or the duct 4, and the air permeability measuring device 18 is connected to this via the flow rate control valve lO1 pressure gauge 11 and air flow meter 12. . The measuring device 1B
is designed to have a structure as shown, for example, in FIG. At the bottom of the sintering material A, there is a wire mesh 14 with a mesh smaller in particle size than the sintering raw material A.
(Of course, a perforated plate etc. is also acceptable) is placed, and
The upper part is open to the atmosphere. To measure the air permeability, a certain amount of kneaded and humidity-controlled sintering raw material A is charged into the sintering raw material filling part 18b of the measuring device 18, and a constant suction pressure is maintained using the pressure gauge 11 as a guide. After adjusting the opening degree of the flow rate control valve 10 so that the amount of air passing through the raw material packed bed is adjusted using the air flow meter 12, the air permeability index of the sintered raw material is calculated according to the following formula.

Air permeability index (JPU) - ((passing air volume) / (suction area))
(Suction pressure)) 0.6 Suction area: ((0,196) π/4) m2 Layer height: m' Suction pressure crab ffmH2O Air volume: N, n37 = Inside the hot air suction duct 4, sintering is performed efficiently. It is necessary to secure the amount of induced air for good progress (generally -800 to -1600
Negative pressure is maintained at about m1H20, and the degree of negative pressure varies slightly depending on the position of the duct in the longitudinal direction of the sintering device (generally, the degree of negative pressure in the front duct of the sintering device is However, if the degree of negative pressure is too low, the measurement accuracy tends to decrease, while if the degree of negative pressure is too high, the measurement operability tends to decrease. The optimal connection position is a duct position where the degree of negative pressure is -800 to 1200 nmH20, preferably around -1000 nmH20.

After determining the air permeability index of the sintered raw material A in this manner, compare that value with the optimum air permeability determined in advance, and increase or decrease the amount of water added to the raw material kneading device 6 according to the difference. By doing so, the air permeability to the sintering raw material is adjusted to the above-mentioned optimum air permeability. Since the optimum air permeability varies slightly depending on the type of raw material (both materials, etc.), particle size, blending ratio, etc., it may be determined in advance through preliminary experiments, but it is usually 20 to 80 according to the JPU index. These operations may be performed manually, but as shown in the figure, the flow rate control valve 10, pressure gauge 11, air flow meter 12, flow rate control valve 8, and flow meter 7 are connected to a control device 15 equipped with a comparison calculation function. It is preferable that the amount of water added can be automatically, accurately, and quickly adjusted in response to changes in air permeability. In any case, the time required to measure the air permeability of sintered raw material A is at most 1
The permeability of the sintering raw material can be maintained at an optimum state by performing this operation at regular intervals, although it may take less than about 0 minutes. As I explained to Shuko, the permeability changes depending on the particle size of the raw materials, the mixing ratio of lime powder, etc., or the return ore ratio.
In order to control such variable factors, it is sufficient to frequently repeat the air permeability adjustment operation before and after the change, and after the air permeability has become almost stable, the frequency of the air permeability adjustment may be returned to the normal adjustment operation frequency.

Incidentally, FIG. 5 is a performance graph showing an example of control when the amount of fine ore powder among the blended raw materials is increased, and the air permeability adjustment according to the present invention is performed at the position of the white arrow. As is clear from this result, even if the blended water content is the same as IY, the air permeability decreases rapidly due to an increase in the amount of fine ore powder (immediately before the white arrow). If the amount is increased and the water content of the sintering raw material is reduced to 1 sq., the air permeability returns to an appropriate value and a good sintering condition can be achieved.

The present invention is roughly constructed as described above, and its effects can be summarized as follows.

[11] Since this is a method of measuring the air permeability of the sintering raw material itself and adjusting the amount of water added according to its fluctuations to restore the appropriate air permeability, the 1-juku mechanism is simple and extremely practical.

(2) Since the negative pressure system of the sintering equipment is directly used as the air source for air permeability measurement, there is no need for a special air source, and the air permeability can be measured under conditions that closely approximate the ventilation conditions inside the sintering equipment. It is possible to perform measurements and has high control accuracy.

(3) Since the air permeability measurement and water addition amount adjustment can be carried out in a very short time, the method has excellent quick response and is extremely suitable for continuous sintering.

[Brief explanation of the drawing]

Figure 1 is a schematic longitudinal cross-section diagram illustrating an iron ore sintering device.
The figure is a graph showing the relationship between the moisture content of the sintering raw material and the electrical conductivity.
Fig. g8 is a schematic overall view showing an example of the present invention, Fig. 4 is a longitudinal cross-sectional view illustrating an example of the air permeability measuring device, and Fig. 5 is an experimental graph showing an example of operation. 1...Sintering raw material supply section 2...Grate 8a...
Ignition part 8b...Sintering part 3C...Cooling part
4... Hot air induction duct 7... Flow meter
8...Flow rate control valve 9...Air permeability measurement pipe line 10...Flow rate control valve 11...Pressure needle 12...
・Air flow meter 18...Performance measuring device
Illusion

Claims (1)

[Claims] In order to sinter the iron ore raw material for blast furnace charging, an air permeability measuring device is connected to the negative pressure system on the hot air induction side of the sintering device via a ventilator equipped with a pressure gauge and an air flow meter. The measuring device is filled with the sintering raw material and its upper surface is opened to the atmosphere, and the air permeability of the sintering raw material is detected from the pressure and air volume of the airflow flowing through the fins in the direction of the negative pressure system, and the sintering is performed accordingly. A method for sintering iron ore raw material, characterized by adjusting the permeability of the sintered raw material by increasing or decreasing the amount of water added to the raw material.