JP3840291B2 - Iron powder production method from steelmaking furnace dust - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention obtains iron powder for fusing, powdered metallurgy iron powder or iron powder as a reducing agent used for the regeneration treatment of etching waste liquid purified from dust generated during steelmaking blowing in a pure oxygen blowing converter, etc. The present invention relates to a method for producing iron powder from steelmaking furnace dust.
[0002]
[Prior art]
In the dust collected from a pure oxygen blowing converter, etc., there are coarse particles mainly composed of metallic iron generated in the middle stage of blowing, where the decarburization reaction is intense, and FeO, Fe ₃ O ₄ generated in the latter stage of blowing. Etc., and fine powder mainly composed of
These are collected in a lump and handled as raw materials with low added value, such as sintered ore for blast furnaces or pellets.
Conventionally, metal iron in such dust is collected, and added value is removed by removing impurities such as scale and slag, and attempts are made to use it for applications such as iron powder for fusing and iron powder for powder metallurgy. It has been.
For example, Japanese Patent Publication No. 57-44724 discloses a first process in which dust generated in a pure oxygen blown steel converter is recovered by a wet method, and the dust is classified to reduce particles of -44 μm size to 30% or less. Next, a second step of removing impurities such as scale and slag from the coarse dust by a wet pulverizer, a third step of removing impurities from the peeled dust to obtain metallic iron, and refining the metallic iron A method for extracting iron powder by the fourth step is described.
[0003]
[Problems to be solved by the invention]
However, in the method described in Japanese Patent Publication No. 57-44724, the third step of obtaining metallic iron by removing impurities from dust is performed by general classification, thin-flow or magnetic separation, There was a problem that a large amount of processing was difficult due to low processing capability and low removal efficiency.
Further, since the fourth step of refining metallic iron is performed in combination with iron oxide refining or purification treatment by dilute acid leaching, continuous treatment is difficult, and crushing treatment or washing treatment in a subsequent step is difficult. In addition to being complicated, there is a problem that a large amount of stable quality purified iron powder cannot be obtained.
[0004]
The present invention has been made in view of such circumstances, and can continuously process dust generated in a steelmaking furnace to produce high-purity refined iron powder with low purity variation in a large amount and at low cost. An object of the present invention is to provide a method for producing iron powder from steelmaking furnace dust.
[0005]
[Means for Solving the Problems]
The method for producing iron powder from steelmaking furnace dust according to claim 1, wherein the raw material dust is recovered from the dust iron powder containing impurities such as CaO generated from the steelmaking furnace by a wet method, and the raw material dust is collected by a ball mill or A wet pulverization step of pulverizing using a pulverizer such as a vibro mill, a water rinsing step of washing the wet pulverized product generated in the step with water and removing the impurities together with fine powder to obtain a washed iron powder, and pickling the washed iron powder. An iron powder production method from steelmaking furnace dust having an elution washing process for eluting and removing the impurities remaining after the treatment, wherein the water washing process is provided with a spiral body that is disposed at an angle and is rotationally driven. A process of washing the raw material dust discharged from the upper part of the spiral body with water while gradually discharging the raw material dust put into the water sedimentation tank by the sediment discharge means. The elution cleaning step is carried out while the washing iron powder put into the acid solution precipitation tank is gradually carried out by the acid solution precipitation carrying means provided with a spiral body that is inclined and rotated. The process comprises a step of pickling the washed iron powder ejected by an acid solution such as hydrochloric acid or sulfuric acid ejected from the upper part of the spiral body, and obtaining purified iron powder from which CaO is removed as much as possible from the acid solution precipitate discharging means. .
The method for producing iron powder from steelmaking furnace dust according to claim 2 is the method for producing iron powder from steelmaking furnace dust according to claim 1, wherein the refined iron powder has a CaO concentration of less than 0.1 wt%.
The method for producing iron powder from steelmaking furnace dust according to claim 3 is the method for producing iron powder from steelmaking furnace dust according to claim 1 or 2, wherein the acid solution has a hydrogen ion concentration (pH) of 0.5 to 3. 0 sulfuric acid or hydrochloric acid solution.
The method for producing iron powder from steelmaking furnace dust according to claim 4 is the method for producing iron powder from steelmaking furnace dust according to claim 2 or 3, wherein the acid solution is sulfuric acid, and the amount of sulfuric acid used is refined iron. 10 to 400 liters per ton of flour.
[0006]
When the concentration of CaO in the refined iron powder is greater than 0.1 wt%, when the refined iron powder is repeatedly used for the recycling treatment of the etching waste liquid, CaO is concentrated in the solution and a scale is generated to generate a nozzle. This is not preferable because clogging occurs or etching ability is reduced.
Moreover, the following points are mentioned as a 2nd reason. In the etching waste liquid treatment, in order to keep the iron concentration in the regenerated liquid constant, the amount of the liquid after the etching waste liquid treatment increases to about 1.5 times that before the treatment. And in order to process this excess etching waste liquid, the waste liquid is blown into a furnace in an oxidizing atmosphere maintained at 650 ° C. to 660 ° C., thereby converting iron chloride in the waste liquid into iron oxide, chlorine gas, hydrogen chloride, etc. An operation for recovering hydrochloric acid and iron oxide is performed. Therefore, when the CaO concentration of the recovered iron oxide becomes high, iron oxide cannot be used for applications such as ferrite, and it is necessary to make the CaO concentration below an allowable value also in that sense.
[0007]
If the hydrogen ion concentration (pH) of the acid solution is less than 0.5, the acid solution becomes corrosive, and the equipment needs to be treated with a special acid resistance, resulting in an increase in equipment maintenance costs. On the other hand, when the hydrogen ion concentration is higher than 3.0, impurities including scale, slag and the like adhering to the iron powder cannot be sufficiently eluted, which is not preferable.
Moreover, when the usage-amount of the sulfuric acid which is the said acid solution will be less than 10 liters per ton of refined iron powder, an impurity will be eluted and removed and the refined iron powder of required purity cannot be obtained. On the contrary, even if the amount of sulfuric acid used is more than 400 liters, the amount of impurities eluted cannot be increased substantially, and no further acid treatment is required, and wastewater treatment in the subsequent process is required. Cost increases.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is an explanatory view showing a part of a steelmaking facility 10 to which a method for producing iron powder from steelmaking furnace dust according to an embodiment of the present invention is applied.
As shown in FIG. 1, a steelmaking facility 10 includes a converter 11 which is an example of a steelmaking furnace, a hood part 12 for collecting dust iron powder and generated gas disposed on the upper part of the converter 11, and a hood part. 12, an exhaust system 13 connected to the exhaust system 12, a chimney 14 exhausting the exhaust system 13, a wet classifier 19 for extracting raw material dust from dust iron powder collected in the exhaust system 13, and an exhaust A dust treatment tank 17 for treating dust iron powder collected by the jet water blown into the second jet port 16 in the system 13, and a thickener 18 for supplying the jet water blown into the second jet port 16; Have
[0009]
The wet classifier 19 includes a dust settling tank 20 for collecting dust collected by the jet water blown from the first injection port 15 in the exhaust system 13 and a rotating spiral body 22 inside the pipe. And a sediment carrying-out means 21 for carrying out a classification process by rolling up and raising the sediment in the pipe. In such a wet classifier 19, by supplying washing water or the like from the opened upper portion of the precipitate carrying-out means 21, the fine powder portion in the precipitate is selectively along the inner wall of the precipitate carrying-out means 21. The dust deposits that flow down and flow out and have a relatively large particle size in the precipitates and from which excess water has been removed are discharged from the upper end of the precipitate carrying means 21 so that the precipitates can be classified or washed. Yes.
The vicinity of the first injection port 15 and the second injection port 16 of the exhaust system 13 has a throttle structure. By blowing water into this orifice, mixing of exhaust gas or dust iron powder and water is effective. The dust iron powder captured by the water is discharged from discharge ports provided on the downstream side of the first injection port 15 and the second injection port 16, respectively.
[0010]
The dust precipitate is processed into a raw material dust (wet pulverized product) by a wet pulverization process in which it is pulverized and polished in a wet state using a pulverizer such as a ball mill or a vibro mill.
FIG. 2 is a configuration diagram of a hydroxy acid cleaning device 23 for performing water cleaning and acid cleaning of the obtained raw material dust.
As shown in FIG. 2, the acid cleaning device 23 includes a water cleaning device 24 and an acid cleaning device 30.
And the water washing apparatus 24 carries out the water sediment carrying out which is arranged in the water sedimentation tank 26 into which the said raw material dust is thrown in, and this water sedimentation layer 26 for processing the sediment of the said water sedimentation layer 26 incline. Means 27, and the acid washing device 30 is configured to remove an acid precipitation tank 32 into which the washed iron powder discharged from the upper part of the water precipitate carrying-out means 27 is charged, and the precipitate in the acid precipitation tank 32. And an acid solution precipitate carrying-out means 33 for scooping up, cleaning, classifying, and removing water.
[0011]
The water precipitate transporting means 27 and the acid liquid sediment transporting means 33 are so arranged that their lower portions are immersed in the water precipitation tank 26 and the acid precipitation tank 32 and have an angle of 10 to 15 degrees with respect to the horizontal direction. In addition, at least the upper part of each of the carrying-out means 27 and 33 has a half structure and is opened.
In addition, spiral bodies 28 and 34 are provided inside the water precipitate discharge means 27 and the acid liquid precipitate discharge means 33 to scrape and deposit the sediment deposited in the precipitation tanks 26 and 32, By rotating the helical bodies 28 and 34 with a motor (not shown) or the like, the precipitates caught in the gaps between the helical bodies 28 and 34 and the carrying-out means 27 and 33 are moved upward along the carrying-out means 27 and 33. It has become.
Further, a water supply pipe 25 and an acid solution supply pipe 31 are arranged on the upper portions of the respective carry-out means 27 and 33, and the cleaning water or the acid solution is supplied to the open portions of the upper portions of the respective carry-out means 27 and 33. it can.
Accordingly, the precipitates that move up and down in each of the unloading means 27 and 33 and the washing water or acid solution that flows down by gravity in each of the unloading means 27 and 33 are effectively stirred and mixed, and Particles having a relatively small particle size are washed away, descend in the respective carrying-out means 27, 33 and are accumulated in the respective sedimentation tanks 26, 32, and the precipitate from which the fine particles have been removed is discharged from the upper part of each carrying-out means 27, 33. It is supposed to be discharged.
[0012]
Then, about the iron powder manufacturing method from the steelmaking furnace dust which concerns on one embodiment of this invention using the said steel manufacturing equipment 10 and the hydroxyl-acid washing | cleaning apparatus 23, based on the iron powder manufacturing flowchart shown in FIG. I will explain.
First, raw material dust containing moisture discharged from the wet classifier 19 of FIG. 1 is put into a primary grinding ball mill (not shown) using a raw material feeder (not shown) (steps S1 and S2 shown in FIG. 3).
The primary grinding ball mill is a substantially cylindrical ball mill capable of processing the raw material dust continuously fed by the raw material feeder, the rotational speed of the cylinder is 20 to 36 rpm, and the amount of balls serving as a grinding medium is 3 to 5 Tons.
The supply amount of water containing raw material dust fed to the primary grinding ball mill is 200 to 1000 liter / hr (average: 270 liter / hr), and the concentration of raw material dust is 50 to 80 wt% (average: 65 wt%).
[0013]
The residence time or processing time of the raw material dust in such a primary grinding ball mill is about 60 to 120 minutes, and a part of impurities contained in the raw material dust can be separated from the iron powder by this wet pulverization process. It has become.
Here, the reason why the wet pulverization step is performed as described above is that the dust itself collected from the converter 11 is a moist powder containing a large amount of moisture as described above, and if the dry process is performed, the drying step is performed as a preliminary treatment. And the subsequent pickling treatment is performed in a wet manner, so that a drying treatment is required again, which is uneconomical.
In addition, when dry pulverization is performed, dust is likely to be generated, and this dust countermeasure is required, and the cost required for environmental countermeasures becomes large.
[0014]
Next, the processed product discharged from the primary grinding ball mill is subjected to a precleaning akins having the same configuration as the wet classifier 19 shown in FIG. 1 to wash away the separated impurities (step S3).
Here, the speed of the fluid that rises in the dust settling tank 20 and overflows is 3 to 10 m / hr (average: 5 m / hr), and the washing water supplied to the opened upper portion of the precipitate discharge means 21. The supply amount was ³ to 25 m ³ / hr (average: 5 m ³ / hr).
The cleaning process by the pre-cleaning akins further separates and removes part of the impurities separated from the iron powder in the processed product, and also removes a small part in the iron powder at the same time, thereby increasing the particle size. The particle size distribution can be shifted in the direction.
[0015]
Subsequently, the mixture discharged from the pre-cleaning akins is pulverized through a secondary grinding vibro mill (not shown) (step S4).
The secondary grinding vibro mill is a vibration pulverizer with a capacity of 1000 liters, the supply amount of water containing raw material dust is 200 to 1000 liters / hr (average: 270 liters / hr), and the concentration of raw material dusts is 50 to 80 wt. % (Average: 65 wt%).
By the wet grinding process using this secondary grinding vibro mill, impurities remaining on the iron powder in the mixture are further finely ground to obtain raw material dust in which the separation efficiency of iron powder and impurities in the subsequent processes is increased. be able to.
Here, FIG. 4 shows a change in CaO concentration, which is an example of impurities in the processed material containing iron powder, and 2-7 wt% before being charged into the primary grinding ball mill (A in FIG. 4). It can be seen that the CaO concentration that was in the range of 5 decreased to the range of 0.5 to 5 wt% after the treatment with the pre-cleaning akins (B in FIG. 4).
However, since a large amount of impurities still remain in such raw material dust (wet pulverized product), the purity is not sufficient as a reducing agent used for the recycling treatment of etching waste liquid, and it is used as it is. Can not.
For this reason, it is necessary to further perform a cleaning classification process on the raw material dust by using a hydroxy acid cleaning device 23 as shown in FIG.
[0016]
First, as a first stage (step S5) of the cleaning process using the hydroxy acid cleaning device 23, the raw material dust is introduced into the water precipitation tank 26 through the raw material dust supply pipe 29 from the upper part of the water cleaning device 24.
As a result, the iron powder portion having a large specific gravity in the raw material dust gradually precipitates, and a sediment layer is formed at the bottom of the water precipitation tank 26.
And the spiral body 28 arrange | positioned in the water sediment carrying-out means 27 is rotated by drive devices, such as a motor.
On the other hand, at this time, the washing water using the water supply pipe 25 3~25m ³ / hr: supplied at a feed rate of (average 25 m ³ / hr), the downward flow by the washing water of the water precipitate out means 27 The raw material dust is thrown into the water precipitation tank 26 and an overflow flow is generated from a portion with a light specific gravity, and the rising speed is in the range of 3 to 10 m / hr (average: 5 m / hr). Adjust to. Thereby, the separation and purification of the raw material dust is performed efficiently.
[0017]
By the above operation, the fine powder portion in the raw material dust is washed out together with the overflow, and the coarse particle portion is selectively discharged from the upper part of the water precipitate discharge means 27 as washing iron powder.
Since most of the impurities are contained in the fine powder portion, the impurities (CaO) in the raw material dust are largely removed in the range of 0.3 to 1.7 wt% as shown in FIG. Washed iron powder having a particle size distribution shifted to the coarse particle side is obtained.
Next, as a second stage (step S6) using the hydroxy acid cleaning apparatus 23, the obtained cleaning iron powder is put into the acid precipitation tank 32 from the upper part of the acid cleaning apparatus 30 through a supply pipe.
As a result, a portion having a large specific gravity in the washed iron powder is gradually precipitated, and a precipitate layer is formed at the bottom of the acid precipitation tank 32.
[0018]
And while rotating the helical body 34 arrange | positioned in the acid-solution precipitation carrying-out means 33 with a motor, an overflow flow is formed in the acid precipitation tank 32, the raising speed is 3-10 m / hr (average: 5 m / hr). hr).
On the other hand, at this time, 98 wt% sulfuric acid having a specific gravity of 1.9 is supplied at a supply rate of 30 to 100 liters / hr using the acid solution supply pipe 31, and the downward flow caused by the acid solution is conveyed to the acid solution precipitate carrying-out means. 33 is formed inside.
At this time, the hydrogen ion concentration (pH) of the acid solution in the acid cleaning device 30 was set in the range of 0.5 to 3.0.
Through the above operation, the fine powder portion in the washing iron powder flows down and is accumulated in the acid precipitation tank 32, and the washing iron powder is washed away by the acid solution flowing down along the acid solution precipitate carrying-out means 33 and the overflow flow in the solution. The impurities contained therein are effectively eluted and removed, the coarse particle portion containing the refined iron powder is selectively discharged from the upper part of the acid liquid precipitate carrying-out means 33, and the supernatant waste liquid in the acid precipitation tank 32 is discharged from the upper part. .
[0019]
And the processed material containing the refined iron powder by which the impurity (CaO) in refined iron powder was removed significantly 0.01-0.10 wt% which is the range below an allowable value as shown to D of FIG. 4 is obtained. be able to.
5 and 6 are graphs showing the relationship between the CaO concentration in the finally obtained refined iron powder and the basic unit of hydrochloric acid and the basic unit of sulfuric acid used in the acid cleaning device 30, respectively.
As shown in FIG. 5 and FIG. 6, if the acid basic unit is too low, the ratio deviating from the allowable amount of CaO in the product becomes high. Conversely, if the acid basic unit exceeds the saturation amount, the amount of decrease in CaO concentration decreases. Acid cost, waste acid treatment cost, equipment maintenance cost will rise.
Therefore, in consideration of the above, it is possible to make the sulfuric acid basic unit necessary for obtaining 1 ton of refined iron powder as a product to be 10 to 400 liters, more preferably in the range of 270 to 400 liters. Is desirable. The hydrochloric acid basic unit can be set to 25 to 700 liters / ton, more preferably 550 to 700 liters.
The sulfuric acid and hydrochloric acid used here are those corresponding to a hydrogen ion concentration (pH) in the range of 0.5 to 3.0, and are treated depending on factors such as CaO content in the raw material dust and other compositions. 5 and 6 show that the CaO concentration in the iron powder to be produced varies.
[0020]
Next, in step S7, the treated product after the acid washing treatment was treated using a secondary washing akins having the same structure as that of the water washing device 24 to wash the acid treated product.
At this time, the remaining acid solution can be removed by supplying cleaning water such as industrial water at a supply rate of 1 to 10 m ³ / hr.
In step S8, the treated product after the acid solution treatment was subjected to an air dryer to remove moisture in an air stream at 150 to 250 ° C.
When the particle size distribution of the purified iron powder after drying was measured, (1) 750 to 150 μm, (2) 150 to 105 μm, (3) 105 to 74 μm, (4) 74 to 63 μm, (5) 63 to 44 μm, (6) 44 μm or less are (1) 0 to 20 wt%, (2) 5 to 40 wt%, (3) 20 to 60 wt%, (4) 5 to 25 wt%, (5) 10 to 30 wt%, (6) ▼ 1 to 19 wt%. The range of (1) may be 710 to 150 μm.
In addition, a typical composition of such refined iron powder is such that the total Fe containing Fe, FeO, and Fe ₂ O ₃ is 96 wt% or more, metal Fe is 92 wt% or more, FeO is 6 wt% or less, and CaO is 0 0.5 wt% or less, SiO ₂ was 0.1 wt% or less, and carbon (C) was 0.7 wt% or less.
[0021]
In the final step S9, the refined iron powder is classified by using a vibration sieve having a sieve mesh in the range of Tyler standard sieve 100 mesh to 150 mesh, and the iron powder on the sieve. Can be used as the purified iron powder for removing copper in the treatment of the etching waste liquid, and the iron powder used for sieving can be used as the purified iron powder for removing nickel.
The 100-mesh and 150-mesh Tyler sieves are sieves having openings of 147 μm and 104 μm, respectively.
[0022]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, The change of the conditions etc. which do not deviate from a summary are all the application scopes of this invention.
For example, in the present embodiment, the case where the water cleaning device and the acid cleaning device are different from each other has been described, but such a water cleaning step and an elution cleaning step are performed using the same wet classifier. It can also be done. In this case, the cleaning iron powder discharged from the wet classifier can be temporarily stored in a storage tank, and the cleaning iron powder taken out from the storage tank can be processed using the same wet classifier.
Moreover, it is also possible to remove impurities in the raw material dust more reliably by repeating the water washing step and the acid washing step by combining a plurality of sets of water washing devices and acid washing devices as necessary.
[0023]
【The invention's effect】
In the method for producing iron powder from steelmaking furnace dust according to claims 1 to 4, the lower part of the water precipitate carrying means is inclined and arranged in a water precipitation tank to which raw material dust is supplied, and the water precipitate carrying means A fine powder containing impurities in the rising and moving precipitate is formed by rotating the helical body provided in the interior to move the precipitate and by forming a downward flow with water jetted from directly above the helical body. The portion is washed away with washing water, and the washed iron powder washed and classified from the upper part of the water precipitate carrying-out means can be obtained.
Subsequently, the spiral of the acid liquid precipitate carrying means arranged in an inclined manner in the acid precipitation tank to which the washing iron powder is supplied is rotated to move the precipitate upward, and hydrochloric acid, sulfuric acid, etc. By supplying the acid solution to form a downward flow, the impurities adhering to the iron powder in the ascending and moving precipitate can be effectively eluted with the acid solution to obtain a purified iron powder.
Accordingly, it is possible to continuously process the dust generated from the steelmaking furnace, and to produce high-purity purified iron powder with a small variation in purity and in a large amount at a low cost.
[0024]
In particular, in the method for producing iron powder from the steelmaking furnace dust according to claim 2, since the CaO concentration of the refined iron powder is less than 0.1 wt%, this refined iron powder is used as a reducing agent in the regeneration treatment of the etching waste liquid. Even when used, CaO is not accumulated in the regeneration cycle. For this reason, the CaO concentration of the etching solution can be maintained below a predetermined level, and it becomes easy to perform the etching process under appropriate conditions.
In the method for producing iron powder from steelmaking furnace dust according to claims 3 and 4, since a sulfuric acid or hydrochloric acid solution having a hydrogen ion concentration limited to a specific range is used for the acid solution, the amount of impurities such as CaO in the refined iron powder is reduced. While being able to maintain at a predetermined level, it is possible to manage the acid solution cost, the waste acid treatment cost, and the equipment maintenance cost within an appropriate range.
In the method for producing iron powder from steelmaking furnace dust according to claim 4, since the acid solution is sulfuric acid and the amount of sulfuric acid used is set in a specific range, impurities can be removed in a more optimized range. There can be produced highly purified iron powder with little variation.
[Brief description of the drawings]
FIG. 1 is a partial configuration diagram of a steelmaking facility to which a method for producing iron powder from steelmaking furnace dust according to an embodiment of the present invention is applied.
FIG. 2 is an explanatory view of a hydroxy acid cleaning apparatus to which the iron powder production method is applied.
FIG. 3 is a flowchart of the iron powder production method.
FIG. 4 is a graph showing changes in CaO concentration in iron powder in each processing step.
FIG. 5 is a graph showing the relationship between CaO concentration in product iron powder and hydrochloric acid basic unit.
FIG. 6 is a graph showing the relationship between CaO concentration in product iron powder and sulfuric acid basic unit.
[Explanation of symbols]
10 Steel making facilities 11 Converter (steel making furnace)
DESCRIPTION OF SYMBOLS 12 Hood | hood part 13 Exhaust system 14 Chimney 15 1st injection port 16 2nd injection port 17 Dust processing tank 18 Thickina 19 Wet classifier 20 Dust precipitation tank 21 Precipitate removal means 22 Spiral body 23 Hydroxic acid washing device 24 Water washing device 25 Water Supply pipe 26 Water precipitation tank 27 Water precipitate discharge means 28 Spiral body 29 Raw material dust supply pipe 30 Acid cleaning device 31 Acid solution supply pipe 32 Acid precipitation tank 33 Acid liquid precipitate discharge means 34 Spiral body

Claims (4)

A wet pulverization process in which raw material dust is recovered from a dust iron powder containing impurities such as CaO generated from a steelmaking furnace by a wet method, and the raw material dust is pulverized using a pulverizer such as a ball mill or a vibro mill; A steelmaking furnace having a water washing step of washing the pulverized product with water and removing the impurities together with fine powder to obtain washed iron powder, and an elution washing step of eluting and removing the remaining impurities by pickling the washed iron powder. A method for producing iron powder from dust,
The water washing step is ejected from the upper part of the spiral body while gradually discharging the raw material dust put into the water sedimentation tank by a water sediment transport means provided with a spiral body that is inclined and rotationally driven. Comprising a step of washing the raw material dust carried out by water,
The elution cleaning step is carried out at an upper portion of the spiral body while gradually discharging the cleaning iron powder charged into the acid liquid precipitation tank by the acid liquid precipitate transporting means provided with a spiral body that is inclined and rotationally driven. Comprising a step of pickling the washed iron powder carried out by an acid solution such as hydrochloric acid or sulfuric acid ejected from
A method for producing iron powder from steelmaking furnace dust, wherein purified iron powder from which CaO has been removed as much as possible is obtained from the acid solution precipitate discharging means. The method for producing iron powder from steelmaking furnace dust according to claim 1, wherein the refined iron powder has a CaO concentration of less than 0.1 wt%. The method for producing iron powder from steelmaking furnace dust according to claim 1 or 2, wherein the acid solution is a sulfuric acid or hydrochloric acid solution having a hydrogen ion concentration (pH) of 0.5 to 3.0. The method for producing iron powder from steelmaking furnace dust according to claim 2 or 3, wherein the acid solution is sulfuric acid, and the amount of sulfuric acid used is 10 to 400 liters per ton of refined iron powder.

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