JPH05195091A - Manufacture of sintered ore - Google Patents

Abstract

PURPOSE:To execute perfect and uniform calcination and to improve the yield of the calcination by measuring exhaust gas temp. at plural positions in the widthwise direction of a pallet at the time of calcining and adjusting oxygen adding quantity in the widthwise direction of the pallet according to this temp. CONSTITUTION:At the time of calcining of sintering ore, on the pallet plural measuring points are decided and divided into plural zones. Average temp. at each block is calculated and order of the calcining speed is decided from this temp. measured data. According to the obtd. calcining speed, the oxygen adding quantity uniformizing the calcining condition in the widthwise direction of the pallet in the ore discharging part is obtd. at each block. The opening degree of an oxygen flow rate adjusting valve is suitably adjusted to add the oxygen. By this method, at the time of calcining, the perfect and uniform calcination can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered ore which can improve the yield of firing.

[0002]

2. Description of the Related Art As is well known, in the sintering method, a mixture of powdered iron ore, powdered coke as a fuel, and powdered limestone as a solvent is placed on a grate called a pallet, and the built-in powdered coke is burned. This is a method for producing a blast furnace charging raw material by partially melting and binding fine iron ore with. As a sintering machine, a DL type (Dwight Lloyd type) of a continuous operation type, a GW type (Greenawald type) of a batch type, and an AI
Although there is B type, most of them are DL type at present.

In the DL type sintering method, a pallet connected is moved endlessly with sprocket wheels at both ends, and when the pallet reaches one end of the sinter machine, the sintering compound raw material is charged and ignited in an ignition furnace. While moving to the other end, the lower suction air gradually lowers the ignition surface as a combustion zone and reaches the other end when it reaches the pallet surface, and is discharged as cake, and the pallet becomes empty and turns over to the original position. It is a return method. The cake is cooled by a cooler, a crusher, and a sieving equipment, and is made to have a particle size suitable for a blast furnace, and sent by a belt. The sintering time is usually about 15 to 30 minutes, and the width of the high temperature zone for sintering from coke ignition to melt solidification by cooling is usually
20 to 80 mm.

By the way, the DL type sintering machine which has been in operation in recent years has been increased in size in order to improve the productivity, and in some cases, the pallet width reaches about 5 m. In such a large DL type sintering machine, the firing is uneven in the pallet width direction.
The problem is that the firing yield is reduced due to (burning unevenness). It is considered that the decrease in firing yield is caused by segregation of the sintering compounding raw materials.

By the way, technical developments relating to improvement of the firing yield during the production of sintered ores have been vigorously carried out. For example, a V-type charging method of charging the sintering compound material into a pallet from a surge hopper in a V-shape, a segregation ore feeding method of segregating the grain size and C content in the ore feeding section, and splitting at the ore feeding section. Various methods have been proposed, such as a method for improving the non-uniform firing state by measuring the temperature directly below the WB in the pallet width direction on the discharge side by controlling the amount of ore supplied by the gate, and a two-stage charging method.

[0006]

However, these techniques control the charging state of the sintering compounding raw material before firing, and the firing yield of the portion which is actually fired unevenly at the time of firing is controlled. It did not improve directly.
That is, in the manufacturing process of the sinter, so-called natural iron ore powder is ordinarily agglomerated as a blast furnace charging material. Therefore, conventionally, homogenization of iron ore such as magnetic separation and sizing, which has been performed immediately after mining, has already been carried out. In addition, improvement of the BL stacking method in the yard and sintering process,
Components such as precision improvement of quantitative cutting device and strengthening of mixing and granulation
Stabilization of particle size is also being promoted.

However, in the production of the sintered ore, a firing non-uniformity phenomenon actually occurs in the width direction of the pallet. Even if the ore supply amount is adjusted by the dividing gates provided in the width direction of the pallet to suppress the firing non-uniformity phenomenon, the firing non-uniformity in the width direction cannot be eliminated. That is, the above-mentioned problem with the conventional technique regarding the improvement of the firing yield at the time of manufacturing the sintered ore is that the variation due to the variation of the particle size and the components of the sintering compound raw material does not always occur in the same tendency. Yes, for example, the phenomenon that occurred in the mining department does not necessarily occur in the mining department at the same time. Therefore, the phenomenon in the mining section may be reversed, and even if the optimum conditions are determined before firing, the conditions are not always optimal throughout firing. It is an object of the present invention to provide a method for producing a sintered ore that can improve the firing yield by always performing a complete and uniform firing during firing.

[0008]

Means for Solving the Problems The present inventor has conducted various studies in order to solve the above-mentioned problems, and measured the actual exhaust gas temperature at the time of firing for each site causing firing nonuniformity, and based on the measurement results, The present invention has been completed by finding that the above problems can be solved by adjusting the firing nonuniformity. Here, the gist of the present invention is a method of manufacturing a sintered ore using a sintering machine, at the time of firing, measuring the temperature of the exhaust gas of a plurality of parts in the pallet width direction, depending on the temperature And adding oxygen by adjusting the amount of addition in the width direction of the pallet.

More specifically, according to the present invention, the temperature of the exhaust gas is measured by, for example, a thermometer directly below the WB installed at a plurality of parts in the width direction of the pallet, and this temperature or the firing rate calculated for each part from this temperature is measured. Determine the degree of firing, that is, the occurrence of firing non-uniformity during firing, and install a width direction divided oxygen addition device in the sintering machine, for example, and determine the amount of oxygen added according to the degree of firing speed obtained. Is adjusted and oxygen is added to make the calcination state of the pallets uniform in the width direction in the mine ore.

In the manufacturing process of the sinter, the powdered iron ore, which is a natural underground resource, and the slag-forming agent are used, so that it is not possible to prevent the firing unevenness in the width direction of the pallet in the sintering machine. It is not an exaggeration to say that it is possible. Therefore, it is important how to stabilize the generated firing nonuniformity. Therefore, in the present invention, the firing non-uniformity phenomenon in the width direction is quantitatively detected during firing, and oxygen is added to the firing delay portion to forcibly increase the firing rate, thereby stabilizing the firing at the completion of firing. It is characterized in that uniform uniform firing is performed.

In the production process of the sinter, the iron ore powder and the slag-forming agent (limestone, SiO ₂ source, etc.) are combined to form an agglomerate suitable as a blast furnace charge. As a heat source, powder coke is usually added. In the sintering machine, after the mixture is ignited by the ignition furnace, the coke is burned by the downward suction air, and the iron ore powder and the gangue component are baked and solidified. Therefore, oxygen in the air reacts with carbon to cause an exothermic reaction based on the following reaction formula C + O ₂ = CO ₂ + Q (calorific value).

According to the present invention, the calcination non-uniformity phenomenon in the pallet width direction, which is considered to be caused by the segregation (particle size, component, C source) of the above mixture, is performed by adding oxygen as a substitute for air. Areas that have not progressed so much
By forcibly increasing the firing rate of (the part where the burn-in delay phenomenon occurs), the burn-in delay phenomenon is eliminated and the baking state in the width direction of the pallet is made uniform at the end of sintering.

[0013]

The structure of the present invention will be described in more detail below.
The sintering machine according to the present invention is not limited to a specific type of sintering machine, and may be a DL sintering machine, or a GW sintering machine or an AIB sintering machine. Good. However, in the following description of the present invention, since most of the currently used sintering machines are DL type sintering machines, the DL type sintering machine will be taken as an example.

First, in the present invention, the firing state in the width direction of the pallet is accurately obtained when firing with the DL type sintering machine.
As a concrete means, for example, a total of 30 points of 10 points in the width direction of the pallet and 3 points in the longitudinal direction are set as temperature measuring points, and a temperature gauge is installed directly under the great bar to measure the temperature of the exhaust gas. Thus, the firing state of one pallet at the time of firing is estimated from the temperature measurement pattern. That is, since the calcination proceeds rapidly in the part where the temperature of the exhaust gas is high (the calcination rate is high), and the calcination does not proceed so much in the part where the exhaust gas temperature is low (the calcination rate is low), the pallet temperature changes from the exhaust gas temperature. Understand the firing condition in the width direction.

1 (a) to 1 (c) schematically show the method of estimating the firing state. As shown in FIG. 3A, 30 temperature measuring points are determined on the pallet, and the neighboring 6 points are divided into A zone or E zone and 5 zone. And the same figure
Calculate the average temperature for each block as shown in (b).
In the example shown in FIG. 2B, the average temperature of the A block is 350 ° C., and the following temperatures are 300 ° C., 320 ° C., 280 ° C. and 300 ° C. Based on these temperature measurement data, as shown in (c) of the figure, the firing speed is ranked as follows: A zone: fast, B zone: slightly slow, C zone: slightly fast, D zone: slow, E zone: slightly slow. Is set in 5 steps.

The mounting position of the thermometer is not particularly limited, but it is located 1/3 upstream from the discharge side of the DL type sintering machine (2/3 from the supply side). If so, the temperature deviation can be sufficiently grasped, and oxygen addition and calcination reaction can be carried out in the remainder to the mine ore section, which is desirable.

Next, in the present invention, oxygen is added by adjusting the addition amount in the width direction of the pallet according to the firing rate obtained as described above. The purpose of adding oxygen is to partially increase the firing rate at the oxygen addition site. That is, when oxygen is added to the portion where the firing rate is slow, the firing rate of coke increases, and the firing reaction proceeds rapidly. In the production of ordinary sinter, the oxygen concentration in the atmosphere (air) is about 21%, but the oxygen concentration in the portion to which oxygen is added according to the present invention increases to, for example, 70% or more.

In the present invention, the concentration of oxygen added is not particularly limited. Generally, the higher the oxygen concentration is, the faster the firing reaction is. Therefore, the higher the oxygen concentration is, the higher the production cost is. On the other hand, although it is not necessary to use extremely high-purity oxygen, it is desirable that the oxygen concentration be at least about 70% by addition. Therefore, the concentration of oxygen added in the present invention is preferably 70% or more.

The method of adding oxygen to the pallet is not particularly limited, but may be carried out using a widthwise dividing oxygen adding device having a hood divided into 5 in the pallet width direction as shown in FIG. It is desirable to accurately control the amount added. It is not necessary to provide hoods on both sides of the pallet in this widthwise divided oxygen adding device. This is because oxygen is not required to be added to both side portions due to the occurrence of a gap between the pallet site plate and the firing zone due to the occurrence of tightness during firing, which increases air leakage.

Using such a widthwise divided oxygen adding device, based on the above-mentioned side temperature result, for each of the five blocks,
The amount of oxygen added to obtain a uniform calcination state in the width direction of the pallet in the mine ore is determined, and oxygen is added by appropriately adjusting the opening of the oxygen flow rate adjusting valve. In addition, a thermometer directly below the grade bar or a red tropics observation device using ITV is installed at the end of the mine ore to judge whether the above oxygen addition amount is appropriate, and further correct the oxygen addition amount. It is more desirable to have the function to do.

Thus, according to the present invention, the firing yield can be improved by always performing the firing completely and uniformly during firing. Furthermore, the present invention will be described with reference to examples, which are illustrative of the present invention and are not intended to limit the present invention.

[0022]

[Examples] The method for producing a sintered ore according to the present invention was confirmed by conducting a pot firing test. First, 49 kg of powdered iron ore and slag forming agent 18
Sintering mixture raw material consisting of kg and powder coke 3 kg
Baking with a (pot diameter of 300 mm) and in the middle of the firing
After a lapse of 20 minutes), the non-uniform firing state was confirmed. An outline of the firing state at that time is shown in FIG. Fig. 3 shows the state after the baking pot has been turned upside down and cooled with N ₂ gas. Fig. 3 (a) shows the position 100 mm from the top of the pot, and Fig. 3 (b) shows the top of the pot. The position of 200 mm from the top and the position of 250 mm from the top of the pan are shown in Fig. 6 (c).

As is clear from FIG. 3, 100 m from the top of the pan
It can be seen that although the firing is almost completely completed at the position of m, the non-uniform firing portion expands downward. In this example, the firing is performed in a state where the amount of air leakage is much smaller than that in a sintering machine in an actual production line, but still significant firing nonuniformity occurs as shown in FIG. 3 (c). From this, it is considered that a more serious firing non-uniform zone occurs in a sintering machine in an actual production line.

Next, 20 minutes after the start of firing, another sintering compound material was charged into the firing pot, and the temperature of the exhaust gas of the pallet was measured at 10 thermometers installed directly under the great bar.

According to the temperature measurement result, oxygen of 90% purity was added in an amount of 1 Nm ³ to a portion where the temperature of the pallet was low, and then 10
Bake for minutes. The width of the red tropical zone in the peripheral portion was measured in the reverse direction of the thus fired product and found to be 35 mm ± 3 mm. Further, it was crushed by a breaker, divided as shown in FIG. 4, dropped by an SI tester 5 times, and then the -5 mm ratio was measured by a 5 mm sieve mesh, and a result of 12% ± 0.8% was obtained. On the other hand, in the conventional method that does not add oxygen,
There was a variation of 15-23%.

Therefore, according to the present invention, it was confirmed by experiments that the firing yield was significantly improved by adding oxygen. In addition, the occurrence rate, yield, productivity, and coke consumption rate of the return ore in the method for producing a sintered ore according to the present invention are compared with those in the conventional method for producing a sintered ore in which oxygen is not added. Each is shown in FIG.

As is apparent from FIGS. 5 and 6, according to the present invention, the amount of return ore produced in the production of sintered ore was reduced, and the firing yield was significantly improved. The yield was calculated as product / calcined amount (cake weight) × 100 (%). As is clear from FIG. 7, the productivity was improved by improving the defective firing zone. As a cause of the improvement in productivity, the reduction of return ore and the increase of the firing rate by the addition of oxygen in the firing failure zone (firing delay state) lead to the increase of the firing rate as a whole.

As is apparent from FIG. 8, the production specifications (coking unit) of the sinter were improved. According to the present invention, when the basic unit of coke according to the prior art is 100,
Sintered ore of the same quality was obtained in 92%. The cause is considered to be the effect of reducing return ore and the effect of reducing the combustion efficiency of coke by adding oxygen. As other improvements, reduction of power source unit and improvement of steam recovery of waste heat boiler were confirmed. It is considered that the productivity was improved for electric power, and the red ore sintered ore input to the cooler was stabilized for steam.

[0029]

As described in detail above, according to the present invention, by performing a perfect and uniform firing at the time of firing,
It has become possible to improve the firing yield. The present invention relates to improvement of the firing yield of sintered ore. In recent years, global warming due to CO ₂ generation has been highlighted as a global environmental problem. As a countermeasure, it is important to suppress the consumption of the C source as a part of energy saving, but the present invention that contributes to the improvement of the firing yield of the sinter is also effective as one of such countermeasures. That is, by improving the firing yield of the sinter, the input coke can be saved and the consumption of the C source can be suppressed. The significance of the present invention having such effects is extremely remarkable.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a method for estimating a firing state in a method for producing a sintered ore according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a method of adding oxygen to a pallet according to the present invention.

FIG. 3 is an explanatory diagram showing an outline of a firing state in Examples.

FIG. 4 is an explanatory diagram showing a crushing situation by a breaker in an example.

FIG. 5 is a graph showing the rate of occurrence of return ore in the example in comparison with a conventional method for producing a sintered ore without oxygen addition.

FIG. 6 is a graph showing a yield in an example in comparison with a conventional method for producing a sintered ore without adding oxygen.

FIG. 7 is a graph showing the productivity in Examples in comparison with a conventional method for producing a sintered ore without oxygen addition.

FIG. 8 is a graph showing a unit of coke in an example in comparison with a conventional method for producing a sintered ore without oxygen addition.

Claims (1)

[Claims] 1. A method of manufacturing a sintered ore using a sintering machine, wherein the temperature of exhaust gas at a plurality of parts in the pallet width direction is measured during firing, and the temperature of exhaust gas in the pallet width direction is measured according to the temperature. A method for producing a sintered ore, comprising adjusting the amount of addition and adding oxygen.