JPS613847A - Method for sintering operation - Google Patents

Abstract

PURPOSE:To manufacture a sintered ore inexpensively with good productivity by mixing lime powder and coke powder in a specified ratio to granulate them while controlling the moisture, charging the granules between bed ore and raw material to be combined for sintering with a specified layer thickness, and sintering them. CONSTITUTION:Each powder is carried out from storage tanks 1, 2 so as to have the ratio of 96-99wt% lime stone powder and 4-1wt% coke powder, then these are granulated while adding water in a mixing granulator 3 to the mixture granules having about 3-9% water, and charged to a hopper 6. On a sintering machine pallet 7, the bed ore 81 is charged firstly from a hopper 4, next a mixing granulation part 82 is charged thereon at 1-4cm layer thickness from a hopper 6, further, the usual combining ore 83 is charged thereon from a hopper 5, and the sintering is performed. In this way, good aeration in sintering bed is maintained. Lime in the part 82 is converted to quicklime by the heat of coke combustion, the particle size becomes small due to the low strength, and almost whole of them come to return ore and are charged to a servo hopper 5.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a sintering method in which limestone is charged into a sintering machine separately from ordinary mixed raw materials and sintered in the production of sintered ore as a raw material for a steelmaking blast furnace. Regarding operating methods.

[Prior art]

Generally, when producing sintered ore for iron-making blast furnaces, the main raw materials are iron ore, coke breeze, limestone, and return ore from the crushing and sieving device of the sintering machine. The materials are mixed, humidity-controlled, granulated, used as sintering compound raw materials, and charged into the pallet of the sintering machine from the surge hopper.

On the other hand, on the grate of the sintering machine pallet, a bedding layer is formed by using sized sintered ore as a bedding layer to ensure air permeability and to prevent fusion to the grate. Charge the sintering compound raw materials. Next, the raw materials for the sintered layer formed on the sintered pallet are ignited by the burner of the ignition furnace, and are successively sintered downward from the top of the ore layer. Air for combustion is sucked downward from the surface of the ore layer by a sintering exhaust fan to become sintering combustion exhaust gas, which is then discharged into the atmosphere after dust removal.

The sintered layer that has been sintered is crushed in a primary crusher and then cooled in a cooler. After being sieved by a primary screen (50 sieves), the +50 sintered ore is re-pulverized in a secondary crusher. Secondary screen (15u sieve mesh) → Tertiary screen (
Sieve in the order of 8th screen) → 4th screen (5th screen), and screen 15 to 50 of each screen. ,．． 1.8-15.
．． Sintered ore with grain size of 5 to 8 is used as sintered ore for blast furnace raw material, and sintered ore with grain size of 15w in the fourth screen is used as return ore, sent to a return ore raw material hopper, and used as raw material for sintering compounding.

In the above sintering operation method, when the amount of fine powder raw material increases, the permeability in the sintering bed deteriorates and the productivity of the sintered ore decreases. In order to increase this air permeability, quicklime was conventionally added as a binder to improve granulation properties. However, quicklime is usually produced by decomposing and firing limestone in a rotary kiln or shaft furnace using fuel such as heavy oil, so the production cost is very high, and when used for sintering, sintered ore is This will increase the manufacturing cost of the product. On the other hand, Japanese Patent Publication No. 58-498 proposes a ``method for charging sintering raw materials'' as a method for producing quicklime using the waste heat of the sintering reaction.

Japanese Patent Publication No. 58-498 discloses a method for charging sintering raw materials into pallets with the aim of reducing NOx in waste gas generated in the sintering process compared to quicklime.

The purpose of this method is to reduce NOX in waste gas, and when charging a pallet with sintered mixed raw materials that have been mixed and granulated using a mixer or pelletizer, limestone is mixed with the mixed raw materials. It is characterized by charging the limestone in one or two or more layers to prevent mixing, and produces quicklime using the waste heat of the sintering reaction of the limestone on the pallet, which is then sintered together with the return ore. This is a method of using it as a blended raw material. However, this method has a low decomposition rate of limestone,
The problem was that the activity of the produced quicklime was also low.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art as described above, and the present invention aims to improve the decomposition rate of limestone and the activity of the produced quicklime in converting limestone into quicklime using the waste heat of the sintering reaction. The purpose of this project is to provide a sintering operation method that uses the quicklime to improve sintering productivity, and at the same time, uses the produced quicklime to replace conventional new quicklime, thereby reducing costs. Ru.

[Summary of the invention]

The present invention has been made to achieve the above object, and its gist is that coke powder is 4 to 1% and limestone powder is 96 to 1% by weight.
99 pieces of mixed raw materials are granulated under controlled humidity, and the mixed granules are placed between 1 to 100 g of mixed granules on the sintering machine pallet and the ordinary sintered mixed raw materials.
The sintering operation method is characterized in that a layer thickness of 4 crn is charged into a sintering machine and sintered.

In order to improve the decomposition rate and activity of limestone, the present inventors focused on coke powder, and using a pot test device,
As a result of various small tests, we have arrived at the present invention.

(1) First, we investigated the effect on the permeability of the lower lime layer by examining the change in sintering time when changing the lime layer thickness and coke mixture. (a) When the lime layer thickness is about 1α, the coke mixture changes. Regardless, the sintering time is almost the same (see Figure 2) (b) When the lime layer thickness increases to 3α and 5 rust, the sintering time becomes longer when no coke is added, but when coke is added, the sintering time is almost the same. This will shorten the sintering time.

(e) When lime powder and coke powder are mixed and granulated by adding water, the sintering time becomes equivalent to a lime layer thickness of 16n.

(Refer to Figure 6) (2) Regarding the properties of the produced quicklime, we investigated the changes in limestone decomposition rate and activity when the coke mixture and lime layer thickness were changed. (a) When the coke mixture was 0. has a limestone decomposition rate of 6
It is low, about 5-80%.

(b) As the coke content increases, the cracking rate improves by 5%
If it becomes more than that, it becomes 90 to 100 inches. (Refer to Figure 4) (C) When viewed in terms of activity, the activity is as shown in Figure 5, and there is an optimum value of 1 to 4% for coke blending.

(See Figure 5) (d) This is because the decomposition rate of limestone is low when the coke ratio is low, but since the activity of the decomposed product is high, there is an optimum value for the coke ratio.

(3) Regarding the influence of quicklime on the productivity of sintered ore,
As a result of providing a lower lime layer on the bedding ore, adding generated quicklime to the mixed raw materials, and examining the sintering time by changing the lime layer thickness, (a) The lime layer thickness was reduced to approximately 6 t-In. As the sintering time increases, the sintering time becomes gradually shorter.

(b) When increasing from 3 cm to 5 cm, the sintering time becomes longer again.

(e) The lime layer thickness is also set to an optimum value of 1 to 4 cIn. (6th
(See figure) (d) Production rate also depends on sintering time.

These findings were confirmed using an actual sintering machine.

The method of the present invention will be described based on FIG.

First, limestone powder and coke powder are cut out from respective storage tanks 1 and 2 at a predetermined mixing ratio of 4 to 1 weight of coke powder to 96 to 99 weight percent of limestone powder, and then water is sprinkled in a mixing granulator 3. The mixture is mixed and granulated, and water is added to obtain a mixed granulated product with a water content of 3 to 9%. The mixture and granules are placed in the bedding ore hopper 4.
The mixture is charged into a mixing granulation unit hopper 6 provided between the sintered raw material surge hopper 5 and the sintered raw material surge hopper 5. A bedding ore 81 is first charged onto a sintering machine pallet 7, and a mixing granulation section 82 is then charged thereon to a predetermined layer thickness, and a normal compounding raw material ore 83 is then charged to form a sintered layer 8. Sintered layer 8 by the burner of the ignition furnace 9
The upper surface layer is ignited, and as the sintering pallet 7 moves, the combustion air from above the sintered layer 8 is sucked in by a separately provided exhaust fan (not shown), and after a certain period of time it is fired and sintered. The cake is discharged from the end of the sintering machine, and the sintering exhaust gas passes through the exhaust fan and is exhausted after exhaust gas treatment.

Quicklime is created by mixing limestone powder and coke powder on the sintering machine pallet.

The baked sinter cake is crushed by a primary crusher 10, cooled by a cooler 11, crushed again by a secondary crusher 12,
It is sieved by screens 13 such as the next screen 131, the secondary screen 162, the tertiary screen 133, and the fourth screen 134, and is sent to the blast furnace as sintered ore with a size of 5 to 50 mm, and the 15M particle size is returned. It is sent to the return hopper as ore.

The calcined quicklime also passes through the crushing and sieving process, but due to its weak strength and fine grain size, almost all of it ends up in the -5m return ore. , -5 return ore is stored in the return ore tank 141 of the raw material blending bunker 14, and the quicklime that has entered the return ore is stored in the lime tank 142 along with the return ore. Ore tank 143. It is cut out at a predetermined blending ratio with each raw material from the coke tank 144, mixed and granulated in a primary mixer 15 and a secondary mixer 16, and charged into the surge hopper 5 described above as a sintering blended raw material.

In addition, in the blending of limestone powder and coke powder, the mixing ratio of coke is less than 1 g, and if it exceeds 4 g, the activity of the generated quicklime will decrease, so the balance should be 1 to 4 g. If the layer thickness of limestone powder and coke mixed granules between the sintering compound raw materials is less than 1.1tyR, the sintering time will be shortened little and the quicklime replacement rate will be small, and if it exceeds 4 layers, the sintering time will be reduced. 1crn to 4c as the production rate decreases for a long time.
The layer thickness was set to rn.

In addition, if limestone powder and coke powder are simply mixed, the permeability will be low, which will increase the sintering time and reduce productivity. Therefore, if water is added and the mixture is granulated at a moisture content of 6 to 9%, the present invention It is possible to achieve the objectives of

[Embodiments of the invention]

Examples of the present invention will be described below.

Example 1 Using a pot test device with a diameter of 30 cIn and a height of 48 crn, using the blended raw materials of the actual machine, a 1 cm layer of limestone and coke blended on the top of bedding ore (marked in the figure) 3 upper M (○) The relationship with the sintering time was determined when the layer thickness was 5 m (marked with Li) and the mixing ratio of coke and limestone was changed. The raw materials used in the actual machine are as shown below.

Blend ore 9 lime, quicklime, total Co96 Return ore mixture ratio standard 84chi 16% -100% 3.5
% (4,0) 25-chi B 86-chi 12-chi 2-chi 10"0% 35% (4,0) 25-chi The results of the pot test are shown in Figure 2.

As shown in Figure 2, when the thickness of the lime layer is about 11 ann, the sintering time is almost the same regardless of the coke blending ratio, but when the lime layer thickness is increased to 3 or 5 tM, the coke blend is reduced to 0. It was found that the sintering time becomes longer when the sintering time is increased, and the sintering time becomes shorter when coke is added. Furthermore, when limestone powder was pre-granulated (x in the figure), the sintering time was shortened as shown by the arrow, and this effect was recognized.

Example 2 Under the same conditions as Example 1, coke and limestone powder were granulated and the layer thickness was 6 mm (marked with ○ in the figure) and 5 m (marked B), and the relationship between coke blending ratio and sintering time I asked for

The results are shown in FIG.

When mixed and granulated as shown in FIG. 3, the sintering time is equivalent to the lime layer thickness 13 in Example 1, and is approximately equal to the sintering time in the standard formulation, so the effect of mixed granulation is clear.

Example 3 A pot test was conducted in the same manner as in Example 2 to determine the properties of the produced quicklime, that is, the relationship between the lime decomposition rate, activity, and coke blending ratio. The results are shown in FIGS. 4 and 5. The measurement of Unao activity was carried out using the amount of hydrochloric acid required for extraction with 4N hydrochloric acid.

As shown in Figure 4, when the coke blending ratio is 0, the limestone decomposition rate is low at 65 to 80 grams, and as the coke blend increases, the decomposition rate improves, and when the coke blending ratio increases to 60 grams or more, the limestone decomposition rate is 90 to 100 grams. becomes.

On the other hand, as shown in FIG. 5, it is clear that the activity has an optimum value between 1 and 4 L% of coke blending ratio.

Example 4 Similar to Example 1, a pot test was conducted in which a mixed granulated layer consisting of 2% limestone powder was provided between the blended raw materials and bedding ore, and produced lime was blended into the blended raw materials. The relationship between the lime layer thickness and the sintering time was determined by varying the quicklime mixture. The results are shown in FIG.

As shown in FIG. 6, the sintering time was shortest when the lime layer had a thickness of about 3 cIn, and a layer thickness of Fi1 to Fi4 gave preferable results.

Example 5 An actual sintering machine () (let width 5 m) was constructed according to the arrangement shown in Figure 1.
), water was added to a mixture of 3 g of coke powder and the balance of lime powder, and the mixed granules having a moisture content of 6 g were charged to a thickness of 6 g onto the bedding ore of a sintering machine pallet.

Next, the blended raw materials (the above-mentioned standard blending ratio) were charged, and connected firing was performed at a let speed of 3.9 m/-.

As a result, the lime decomposition rate was 95% and the activity was 120 C, C/4.
Quicklime of Nrt is obtained, and the productivity of sintered ore is 1.4.
The result of t/d h r was obtained and the normal 1.3 t/m
It was confirmed that this was an improvement of about 8 cm compared to the 2000 hr, and that the unit consumption of limestone was also reduced.

〔Effect of the invention〕

According to the sintering operation method of the present invention, unlike the conventional sintering method that uses sintering waste heat to generate quicklime, the decomposition rate of limestone is high, and quicklime with high activity is produced. Therefore, the sintering productivity is improved and the production cost of sintered ore is significantly reduced.

[Brief explanation of drawings]

Figure 1: An explanatory diagram of the method of the present invention; Figure 2: A diagram of the relationship between coke blending ratio and sintering time in the first embodiment of the present invention;
FIG. 6 is a diagram of the relationship between coke blending ratio and sintering time in the second embodiment, and FIGS. 4 and 5 are in the sixth embodiment. FIG. 6 is a diagram showing the relationship between coke blending ratio, lime decomposition rate, and activity, and FIG. 6 is a diagram showing the relationship between lime layer thickness, quicklime blending ratio, and sintering time in the fourth embodiment. In the figure 1... limestone powder storage tank, 2... coke powder storage tank,
6...Mixing granulation device, 4...Bedding hopper, 5...
・Surge hopper, 7... Sintering machine pallet, 8...
Sintered layer, 81--Bedding layer, 82--Mixed granulation layer, 83--Blended raw material layer, 9--Ignition furnace, 10--
- Crusher, 13... Screen, 14... Raw material blending bunker, 15.16... Fusa.

Claims (1)

[Claims] Weight ratio: 4-1% coke powder, 96-9% lime powder
A 9% mixed raw material is granulated with controlled humidity, and the mixed granules are placed between the bedding ore on the sintering machine pallet and the normal sintered mixed raw material.
A sintering operation method characterized in that a layer thickness of 4 cm is charged into a sintering machine and sintered.