JP3502064B2 - Method for producing agglomerates of ironmaking raw materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to an agglomerated carbonaceous material interior
Hot iron by reducing reduced iron source and dissolving reduced iron or reduced iron
Belongs to the technical field of manufacturing
Slag and metal melt
Lowers the melt separation temperature and further reduces the sulfur content in metallic iron
Belonging to the technical field of agglomeration of ironmaking raw materials
It is. [0002] 2. Description of the Related Art Conventional agglomerates are iron ore powder which is an iron source.
Is mixed with coal powder, which is a coal material, to soften and / or reduce coal.
Or pressure molding within the melting temperature range, 5 minutes at the molding temperature range
By performing the above degassing process to produce agglomerates,
After that, the apparent density of reduced iron that reduced agglomerates was 2300
kg / m^Three It is the agglomerate which becomes above. The reason is stone
Press forming within the softening and / or melting temperature range of charcoal
As a result, the contact area between coal and iron ore powder increases.
The apparent density increases. As a result, thermal conductivity is good
This is because the reduction rate can be increased. Also,
Inorganic materials such as bentonite used in forming agglomerates
No need for material binders, which improves the quality of reduced iron
And increase the apparent density of reduced iron.
Can be. The apparent density of reduced iron is 2300kg / m^Three
Above, when the reduced iron is melted, the reduced iron
Dissolved in a short time without floating on the slag inside
There is an advantage to say. [0003] However, the conventional agglomeration
In products, some of the sulfur components contained in the raw materials are reduced iron,
Contained in metallic iron during the melting process of the original iron, lowering the quality of the hot metal
And desulfurization during the steel making process becomes indispensable.
This will increase costs. Also, if the melting point of the reduced iron slag is high,
Dissolution of slag and metal is delayed during dissolution of source iron
Metal metal separation efficiency is reduced, and
It takes a long time to increase the melting energy cost
Become. [0005] The present invention has been developed to solve the above problems.
Made by mixing iron source and carbon material, softening and melting the carbon material
Pressure molding within the temperature range, apparent density 2300kg /
m^ThreeWhen producing the agglomerates described above, iron sources and coal
Add the desulfurizing material as an auxiliary material to the raw material
By adjusting the basicity of the slag component,
Reduces the content of sulfur components in metallic iron,
Agglomeration of steelmaking raw materials that can improve separation efficiency
The purpose is to provide things. [0006] [Summary of the Invention]Iron source and charcoal
And the raw material obtained by mixing
Pressure molding inside, apparent density is 2300kg / m ^Three Less than
In producing the agglomerate, the grease of the carbon material is used.
The maximum flow rate MF is set to logMF ≧ 1.5,
Basicity of slag component (CaO / SiO _Two ) Is 1.
CaO is contained in the raw material so as to be in the range of 0.5 to 1.5.
Adding a substance and reducing the agglomerate in a reduction furnace
The melting and separation temperature of slag and metal is 15
00 ° C or less and the sulfur content in metallic iron is 0.04% or less
Method for producing agglomerates of iron making raw material
Is. [0007] [0008] [0009] The carbon material as a reducing material is 260
If the temperature exceeds ℃, thermal decomposition starts and softens and melts, and exceeds 550 ° C
And solidifies. In this temperature range, iron ore powder (iron source) and carbonaceous material
Is mixed and pressed to melt in the voids between iron ore powder particles.
Carbon material easily penetrates and firmly connects iron ore powders.
You. For this reason, conventional methods require a binder.
However, in the present invention, a binder is not required, and
Rank can be raised. In the present invention, this softening and melting property
Is used. Further, hot forming is performed in a temperature range of 260 to 550 ° C.
The formed agglomerate is allowed to stand at this molding temperature range for 5 minutes or more.
By performing degassing, the carbon material in the agglomerate
These volatiles are removed to increase the strength of the agglomerate and then reduced.
It is possible to prevent cracks caused by blistering of agglomerates in the process.
Wear. The apparent density of agglomerates after degassing is
Because of the shrinkage, the agglomerates before and after degassing
The apparent density hardly changes. But degassing
The swelling of the agglomerates during the reduction process
The apparent density of the reduced iron increases. FIG. 4 shows the relationship between the apparent densities of agglomerates and reduced iron.
Show the person in charge. As shown in the figure, the apparent density of reduced iron
As the apparent density of the previous agglomerate increases,
It increases in proportion. Also, 50 for hot formed briquettes
When degassing is performed at 0 ° C for 30 minutes,
Briquette swelling disappears and apparent density increases.
You. Thus, degassing hot-formed briquettes
To reduce the apparent density to 2300 kg / m^Three Less than
By doing so, as shown in FIG.
When melting the original iron, the apparent density of the reduced iron
The density becomes larger than the apparent density of the slag, and the reduced iron
Submersion in slag promotes dissolution, increasing productivity during dissolution
improves. [0012] The above method for producing agglomerates of ironmaking raw materials is described.
In addition, one of the present inventors has filed Japanese Patent Application No. 10-081.
No. 540. [0013] DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
You. FIG. 1 shows a production process of agglomerates of iron-making raw materials according to the present invention.
1 shows an example of a conceptual diagram of a process. As shown in the figure,
The carbonaceous material and iron ore that are the raw materials are crushed by a crusher. At this time
In addition, CaO, an auxiliary raw material that is a desulfurizing material in iron ore or carbonaceous material,
Pulverize the ingredients together with the ingredients. Similarly, Hara
When adjusting the basicity of the slag component of the feed,
Or a carbonaceous material with a CaO-containing substance as an auxiliary material
Crush into pieces. Quicklime, slaked stone as CaO-containing substances
Ash, limestone and the like can be used. Carbon materials are iron ore
Pulverize to 1mm or less to keep the mixed state of
Is preferred. In addition, the carbonaceous material
Higher fluidity is preferable, and the blending ratio of carbon
Is preferably 30% or more by volume in the agglomerate. Grinding
Regarding the drying and preheating of iron ore and carbon material afterwards,
To reduce temperature fluctuations during mixing with iron ore due to fluctuations
Dry at a temperature of 200 ° C or less with a rotary dryer.
Dry and remove adhering water. On the other hand, iron ore is mixed with carbonaceous materials.
Rotary kill to reach the target molding temperature when
Preheat with heat. The mixing of the dried or preheated iron ore and the carbonaceous material includes:
Can be mixed in a short time to prevent overheating of part of carbon material
For example, a two-shaft mixer commonly used in this industry
Used. Adjust desulfurizer and basicity when grinding raw materials
When CaO as an auxiliary material is not added, separately pulverized Ca
Add O to the mixer and mix with iron ore and charcoal
Is also good. Also, keep the mixer in place to ensure the molding temperature.
Warm up. The mixed iron ore, carbonaceous material and CaO are heat
Adds to agglomerates (briquettes) using a forming machine for cold forming
Press forming. In press molding, agglomerates endure handling
It is sufficient if sufficient strength can be obtained, and therefore, molding pressure
The force is 1.5 t / cm or more. Molded in this way
As shown in FIG. 6 (b), the agglomerates were iron ore powder particles.
The molten carbon material penetrates into the gaps between the iron ores, strengthening the iron ores.
And the area of contact between the carbonaceous material and the iron ore also increases.
ing. In addition, the mixer and the molding machine have a closed structure,
Ejector, etc., for gas generated in a molding machine and a molding machine
The collected gas is collected at the end-of-reduction zone in the reduction furnace.
And is used as a reducing gas. The agglomerate after molding has a small amount of volatile components remaining.
You. When this is charged into the reduction furnace as it is, volatile components are generated.
Causes the agglomerates to expand, possibly cracking
Become To prevent this and increase the strength of agglomerates
At a temperature near or above the molding temperature.
The agglomerate is charged into the gas / solidification tank to solidify the carbon material,
Sometimes volatiles are also reduced. The agglomerates without volatiles are
As shown in FIG. 6 (c), gas holes (fine
Pores) are observed. Agglomerates produced in this way
The apparent density of the compound is 2400 kg / m^ThreeThat is all. Subordinate
Therefore, this degassing and solidification treatment prevents the collapse of agglomerates
However, this is an important step to obtain a high-density reduced iron.
The agglomerate obtained in this way is removed from the degassing / solidification tank.
After leaving, it is sieved, the upper part of the sieve is charged into a reduction furnace, and the powder under the sieve is
The raw material is returned to the mixer again. When producing agglomerates, CaO is used as a desulfurizing material.
By adding, during reduction or dissolution of reduced iron
On the other hand, CaO reacts with sulfur component contained in
Forming CaS to fix sulfur component contained in carbonaceous material
To reduce the sulfur content in metallic iron
You. In addition, iron sources containing sulfur components (including iron ore)
In some cases, some sulfur components react with CaO and become fixed.
Reduce the sulfur content in metallic iron. FIG. 2 shows the amount of CaO added and the sulfur component in metallic iron.
(S) is a graph showing the relationship with the amount, the abscissa is the agglomerate versus
The vertical axis indicates the S content in metallic iron.
Show. As shown in the figure, when the amount of CaO added increases,
It can be seen that the S content in iron decreases. Therefore, iron source
Want to desulfurize by knowing the amount of S contained in carbon and carbonaceous materials by analysis
By adding an amount of CaO corresponding to the amount of S to the raw material,
Therefore, it is possible to desulfurize the S content in the metallic iron to a predetermined amount.
You. Also, CaO is added during the production of agglomerates.
By adjusting the basicity of the slag component, the reduced iron
The melting point of slag can be lowered
Increase the efficiency of slag / metal separation and obtain clean metallic iron
be able to. Also, reducing the melting point of slag reduces
The melting temperature of iron decreases and the melting time can be shortened.
You. Furthermore, as described above, CaO acts as a desulfurizing material and
The quality of the pig can be improved. As a result, during the steelmaking process
Also reduces the desulfurization cost. SiO affecting basicity_Two Is iron in the raw material
It is mixed with ore and carbonaceous materials. Therefore, salt
Included in iron ore and carbonaceous materials to adjust the basis
SiO_TwoKnow the amount by analysis and match the basicity you want to adjust
By adding a small amount of CaO, the slurry in the reduced iron
It is possible to adjust the basicity of the
You. FIG. 3 shows basicity and slag / metal melting temperature.
Relationship between basicity and basicity and S content in metallic iron
The horizontal axis shows the basicity in reduced iron, and the left vertical axis
Shows the slag / metal melt separation temperature, and the right vertical axis shows gold
It shows the S content in the metallic iron. As shown in the figure,
Slag-metal melt separation temperature changes
You. On the other hand, the S content in metallic iron decreases as the basicity increases.
You can see that it goes down. As is apparent from FIG. 3, the present invention
Basicity of slag component of original iron (CaO / SiO_Two) To 1.
When the reduced iron is melted by adjusting the range from 0.5 to 1.5
In addition, the slag / metal melting / separation temperature is set to 1500 ° C or less,
S content in metallic iron can be reduced to 0.04% or less
You. In this way, the auxiliary materials are mixed in advance in the agglomerate
In this way, the agglomerates and auxiliary materials can be separated separately in a vertical furnace.
Rather than charging, less auxiliary ingredients are required and the amount of
If they are the same, the desulfurization efficiency increases. Therefore, agglomerates
By mixing the auxiliary raw materials inside, the amount of auxiliary raw materials can be reduced.
Thus, desulfurization efficiency can be improved. Secondary material is 1
The particle size of less than mm increases the density and strength of agglomerates.
And the desulfurization efficiency increases. Reduced iron obtained by reducing agglomerates in a reduction furnace is manufactured by
It can be charged to the blast furnace as iron raw material, or
It can also be used as a raw material for pig iron by charging it into a pora furnace.
You. The agglomerate of the raw material for iron making before reduction is
As a raw material, it can be charged into a vertical furnace in this state.
You. Here, FIG. 7 shows the agglomerate before reduction (unreduced agglomeration).
Tumbler rotation strength based on JIS M8712
A test was conducted, and the -1 mm powder ratio and the crush strength at the time of the test were compared.
It shows the relationship. As shown in the figure, unreduced agglomeration
If the crushing strength of the compound is 400 N / piece or more, -1 mm powder
Rate is reduced to 17 mass% or less, and it can be used for vertical furnaces such as blast furnaces.
It can be understood that it can withstand the handling at the time of charging. Not yet
Basicity of slag component of reduced agglomerate (CaO / SiO
_Two ) Is in the range of 1.05 to 1.5,
If the cellar maximum flow rate MF is logMF ≧ 1.5, the pressure is
A crushing strength of 400 N / piece or more was obtained (see Example 3 described later).
) And a vertical furnace such as a blast furnace. In addition,
ー The highest flow rate of the cellar is measured based on JIS M8801.
It is a specified value. [0025] Embodiment 1 The present invention will be described below with reference to embodiments.
The carbonaceous material shown in Table 1 and the iron ore powder shown in Table 2 were combined with a carbonaceous material of 22%
After mixing at a mass ratio of 78% of iron ore powder, the composition shown in FIG.
As a desulfurizer in the mixer before shaping, Ca
3% by mass ratio of O was added and mixed. Molding 450
At about 3cm in volume at a molding pressure of 2t / cm^ThreeAgglomeration of
The product was formed on a twin roll forming machine. 500 ° C, 30 after molding
For a minute. View of agglomerates at this time
Hanging density is 2300kg / m^ThreeThat was all. In addition,
ー The highest flow rate of the cellar is measured based on JIS M8801.
Specified. [0026] [Table 1] [0027] [Table 2] [0028] The above agglomerate is placed in a horizontal reduction furnace at 1400 ° C.
For 10 minutes. The results are shown in Table 3.
You. As shown in Table 3, the metallization ratio of reduced iron (M.Fe /
T. Fe) is 98.45%, and S in metallic iron is 0.06%.
%. As a comparative example, no desulfurizing material was added.
In the case, S in the metallic iron was 0.11%. like this
Was formed by adding quicklime as a desulfurizing material to the raw material
The agglomerates are desulfurized during the reduction process, and the desulfurization
It is reduced. The apparent density of reduced iron is 2400kg / m^Three
It is. [0029] [Table 3] [0030] Example 2 As in Example 1, the results are shown in Tables 1 and 2.
Carbon material and iron ore powder, mass of carbon material 22%, iron ore powder 78%
After mixing at a ratio, the base was added to the mixer before molding shown in FIG.
Add CaO for adjusting the degree of mixing, mix and adjust the basicity.
Adjusted to 1.2. Molding conditions and degassing after molding
The conditions are the same as in the first embodiment. A reduction melting experiment was performed on the agglomerate.
As a result of measuring the slag / metal melt separation temperature,
The melt separation temperature was 1440 ° C. Soshi
At this time, S in the metallic iron was 0.03%. this
As described above, CaO for adjusting the basicity is added to the raw material.
The formed agglomerate is used as slag and meta during the dissolution process after reduction.
The melting temperature can be lowered, and the melting temperature can be lowered.
You. In addition, desulfurization is also performed, reducing desulfurization processing in subsequent processes
Is done. In the reduction melting experiment, the high-temperature softening of iron ores was performed.
The test was conducted based on the chemical test method. [0032] [Example 3] As the carbon material, the highest flow rate MF
4 kinds of coals in logMF range from 1.23 to 3.54
Each is crushed and the particle size is 74 μm or less 70 to 80% by mass
Coal powder was used. Iron ore shown in Table 2 for each coal powder
Mixed with stone flour, mass ratio of coal powder 22%, iron ore powder
Then, the limestone powder shown in Table 4 was added to the mixer before molding shown in FIG.
Are added in various amounts and mixed, and the basicity is adjusted.
It was changed in the range of 0.0 to 2.0. Molding conditions and
The degassing conditions after shaping are the same as in Example 1. [0033] [Table 4] The crushing strength of the agglomerate was measured, and the
FIG. 8 shows the basicity of the slag component in the agglomerate (CaO /
SiO_Two ) And the grease cellar maximum flow rate MF and lump of charcoal
This is shown as a diagram showing the relationship between the crushing strength of the formed material. Figure
The amount of limestone added increases the slag component in the agglomerate.
Basicity (CaO / SiO_Two ) As the pressure increases
The crushing strength tends to decrease, but it is the best charcoal
The crushing strength may increase as the flow rate MF increases.
I understand. In addition, as is clear from FIG.
Basicity (CaO / SiO_Two ) Is 1.05-1.
In the range of 5, the maximum flow rate MF of the charcoal
By setting logMF ≧ 1.5, the crushing strength is 4
Agglomerates of more than 00N / piece can be obtained and
It can be charged into vertical furnaces such as blast furnaces.
Wear. [0035] As is clear from the above description,
DepartureClearlyThe agglomerates of the related steelmaking raw materials are C
Since the aO-containing substance is added, the added CaO is removed.
Produces a sulfurizing action and a basicity adjusting action.
It is possible to obtain low-purity metallic iron. Also, agglomeration
During the melting of reduced iron, which has reduced
To reduce melting energy costs and reduce desulfurization
Since it is performed, desulfurization treatment in a subsequent step is reduced. Ma
WasThe present inventionThe agglomerates of steelmaking raw materials related to
Uses a carbon material with a maximum flow rate of the greaser above a certain value
Because of this, the crushing strength is high and it is hard to be powdered.
Furnace can also be charged.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a conceptual diagram of a production process of an agglomerate of an iron-making raw material according to the present invention. FIG. 2 is a diagram showing the relationship between the amount of CaO added and the amount of S in metallic iron. FIG. 3 is a diagram showing a relationship between basicity and a slag / metal melt separation temperature, and a relationship between basicity and the S content in metallic iron. FIG. 4 is a diagram showing the relationship between the apparent density of agglomerates before reduction and the apparent density after reduction. FIG. 5: apparent density of 1600 kg / m ³ and 2400 k
It is a figure which shows the result when the agglomerate after reduction of g / m < ³ > was melt-tested in the crucible. FIG. 6 is a schematic view of the internal structure of the agglomerate, where (a) is a conventional agglomerate, (b) is an agglomerate before degassing, and (c)
FIG. 3 is a schematic view of the internal structure of the agglomerate after degassing of the present invention. FIG. 7 is a diagram showing the relationship between the crushing strength of agglomerates and the powder ratio in a rotational strength test. FIG. 8 is a graph showing the relationship between the basicity of the slag component in the agglomerate and the maximum flow rate of the ghee cellar of the carbonaceous material, and the effect of the crushing strength of the agglomerate.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuzo Ito 1-6-14 Edobori, Nishi-ku, Osaka-shi, Osaka Nissay Higobashi Building Inside Industrial Service International Inc. (56) References JP-A-11- 92833 (JP, A) JP-A-62-50420 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22B 1/00-61/00 C21B 13/10

Claims (1)

(57) [Claims] [Claim 1] A raw material obtained by mixing an iron source and a carbon material is
Pressure molding within the softening and melting temperature range of
The degree is 2300 kg / m ³ Producing agglomerates that are above
On the occasion, log the maximum flow rate MF
MF ≧ 1.5, basicity of slag component in the raw material
(CaO / SiO ₂ ) Is in the range of 1.05 to 1.5
And adding a CaO-containing substance to the raw material,
The slag and
Metal melt separation temperature of 1500 ° C or less and metallic iron
Characterized in that the sulfur content in it is less than 0.04%
Method for producing agglomerates of ironmaking raw materials .