CN107186216B - A kind of method that low cost low temperature direct-reduction prepares superfine iron powder - Google Patents
A kind of method that low cost low temperature direct-reduction prepares superfine iron powder Download PDFInfo
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- CN107186216B CN107186216B CN201710407863.4A CN201710407863A CN107186216B CN 107186216 B CN107186216 B CN 107186216B CN 201710407863 A CN201710407863 A CN 201710407863A CN 107186216 B CN107186216 B CN 107186216B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
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Abstract
The present invention relates to powder metallurgical technology more particularly to a kind of methods that low cost low temperature direct-reduction prepares superfine iron powder, specifically include that step 1, ultrapure iron concentrate powder is crushed and is classified, the ultrapure iron concentrate powder after being crushed and classified；Step 2 is aoxidized to obtain Fe to the ultrapure iron concentrate powder after being crushed and classified2O3Powder；Step 3, using reducibility gas by Fe2O3Powder is restored；Step 4, reduction terminate, and superfine iron powder preparation is completed.The invention has the benefit that raw material ultrapure iron concentrate powder amount is inexpensive greatly, method is simple, energy-saving and environmental protection, and can with serialization, produce superfine iron powder in enormous quantities；First ultrapure iron concentrate powder is crushed and is classified, is oxidized to Fe2O3It restores to obtain superfine iron powder after powder, can be effectively reduced the partial size and oxygen content of prepared superfine iron powder；Reduction process is charged using multilayer boat, can either improve the production efficiency of superfine iron powder, and can improve the utilization rate of reducing gas, has industrial value.
Description
Technical field
The present invention relates to powder metallurgical technologies more particularly to a kind of low cost low temperature direct-reduction to prepare superfine iron powder
Method.
Background technique
Iron powder is raw material important in powder metallurgy industry, is widely used in the fields such as automobile, household electrical appliances, metallurgy, chemical industry.
Superfine iron powder refers generally to thin iron powder of the average particle size less than 10 μm, compared with common iron powder (- 200 mesh), since its granularity is small, than
Surface is big and performances, the application range such as activity height and special electricity, magnetic, light, catalysis, absorption are boundless；With powder
Metallurgical product develops to the directions such as high-compactness, high intensity, complex-shaped, and the dosage of superfine iron powder is more and more.
The method for preparing superfine iron powder has very much, can be divided at present following several:
(1) reduction method, including gas phase reduction process and solid phase reduction method, gas phase reduction process mainly utilize FeCl2Equal molysite
Gas phase is formed at high temperature, passes through H2Molysite reduction is produced superfine iron powder, but this method technical process by equal reducibility gas
It is not easy to control, the high requirements on the equipment, it is difficult to be formed and be produced in enormous quantities；And solid phase reduction is then to utilize ferrous oxalate (FeC2O4·
2H2O), FeOOH (FeOOH) etc. is as presoma or directly by Fe2O3The oxide of equal iron is utilized as solid phase
H2Equal reducibility gas are restored to obtain superfine iron powder under certain conditions, and this method is possible to carry out large-scale ultra-fine
PRODUCTION OF IRON POWDER, but technical process is longer, higher cost.
(2) microemulsion method, microemulsion be transparent water droplet in the oil or the monodisperse system that is formed in water of oil droplet, dispersion
Particle diameter is 5~100nm；The thickness of particle size or aggregation molecular layer is close to nanoscale in Sturctures of Microemulsions, thus to receive
The preparation of rice material provides effecting reaction device；The microemulsion method of superfine iron powder is in microemulsion system using organic strong reductant
(such as NaBH4) reduction FeCl2Etc. low price molysite, then by water, organic matter and other suspended matters remove, it is vacuum dried, use magnetic separation
Method selects iron granules；This method is suitable for the preparation nanoscale superfine iron powder of small lot, but is poorly suited for large scale preparation
Micron-sized superfine iron powder.
(3) vacuum vapor deposition method, refer to makes evaporation of metal in a vacuum, then by the cooling of its steam and condensation, and obtains gold
Belong to the method for superfine powder；The general epigranular of this obtained metal powder of method, narrowly distributing；But this method higher cost,
It is equally poorly suited for being prepared on a large scale micron-size superfine iron powder.
(4) carbonyl process, the preparation method of carbonyl iron dust generally first close iron powder and CO under certain temperature and pressure
As Fe (CO)5, then by Fe (CO)5It directly decomposes at a certain temperature and produces superfine iron powder；But due to carbonyl process system cost compared with
Height, and Fe (CO)5Be toxic explosive substance with raw material CO, entire process flow it is complicated for operation, these hinder carbonyl process
Application popularization.
(5) ball-milling method, application No. is 201110065044.9 patents to disclose the method using ball milling for Fe2O3Powder
It is milled to micron order, Ball-milling Time leads to hydrogen after dry in 7~48h, in 280~360 DEG C of at a temperature of going back through 5~20min
Original obtains superfine iron powder；And application No. is 200710063632.2 patents, carry out ball milling to iron oxide with ball mill first,
After the granularity of iron to be oxidized reaches≤10 microns, ball milling built-in temperature is risen to 200~400 DEG C, and be passed through reducibility gas (such as
H2Or CO) restored, to generate superfine iron powder.
(6) fluidize state method, application No. is 201210219328.3 patent disclose using fluidisation state method it is ultra-fine to carry out
The production method of iron powder: use the iron oxide red of steel plant's recycling purification as raw material, be conveyed to through feeding device from fluidized bed top
Fluidized bed, feeder are passed through also Primordial Qi and protection gas from fluidized-bed bottom, and gas makes after the gas distribution grid in fluidized bed
Raw material fluidisation, while agitating device improves the fluidized state of raw material by the blade rotation in fluidized bed, enhances gas-solid contact, mentions
High reaction efficiency；Heating device makes temperature in fluidized bed reach reduction temperature, later, starts reduction reaction, Fe in fluidized bed2O3
It is reduced into Fe；But fluidized bed process is easy to produce " defluidization " problem when producing iron powder, that is, is restored to one timing powder of metal Ferrum content
Body loses fluidisation ability because of bonding.Many grind also has been carried out to the defluidization phenomenon in Iron Ore Powder fluidizing reduction process both at home and abroad
Study carefully, and the patent of application number 201110136868.0 discloses the defluidization solved the problems, such as in fluidized bed process production superfine iron powder, i.e.,
The horizontal baffle for having centre bore is added in a fluidized bed reactor, it is existing to solve the defluidization in fluidization process production superfine iron powder
As.
Although these methods can't in conclusion having had investigated the method for much preparing superfine iron powder at present
It realizes and extensive, low cost prepares micron-sized superfine iron powder.
Summary of the invention
In view of above-mentioned analysis, the present invention is intended to provide a kind of low cost low temperature direct-reduction prepares the side of superfine iron powder
Method extensive, inexpensive prepares powder metallurgy industry superfine iron powder to solve the problems, such as to be unable to satisfy in the prior art.
The purpose of the present invention is mainly achieved through the following technical solutions:
A kind of method that low cost low temperature direct-reduction prepares superfine iron powder, mainly comprises the steps that
Ultrapure iron concentrate powder is crushed and is classified by step 1, the ultrapure iron concentrate powder after being crushed and classified；
Step 2 is aoxidized to obtain Fe to the ultrapure iron concentrate powder after being crushed and classified2O3Powder；
Step 3, using reducibility gas by Fe2O3Powder is restored；
Step 4, reduction terminate, and superfine iron powder preparation is completed.
The present invention uses ultrapure iron concentrate powder for raw material, and this raw material sources are extensive, cheap, and due to this super
Pure iron concentrate powder main component Fe3O4Content can achieve 99% or more, property is firmly crisp, be easy to be ground into thinner particle,
It is not concerned about and is oxidized in crushing process, crushing process is easy to carry out；Ultrapure iron concentrate powder after being crushed and classified carries out oxygen
Change preparation Fe2O3It is restored after powder and prepares ultrapure iron powder, ultrapure iron concentrate powder can sufficiently obtained in low temperature and in the short time
Reduction, and the granularity of the superfine iron powder generated is more tiny compared with the prior art.
Meanwhile ultrapure iron concentrate powder be from specific Iron Ore Powder by it is selected and formed, be mainly characterized by purity is high,
Measure big, at low cost, formation Fe after then being refined, being aoxidized by the ultrapure iron concentrate powder2O3, however it is selected in the prior art
The raw material selected are iron oxide red, and main component is also Fe2O3, but the cost of iron oxide red wants high compared with ultrapure iron concentrate powder
, according to quality difference at 3400 yuan/ton~5000 yuan/ton, but ultrapure iron concentrate powder
Price be 1600 yuan/ton, plus processing cost also only 1900 yuan/ton or so；In the process of the present invention in raw material with
It is previous different, there are more apparent economic advantages.
Further, in the step 1, the breaking method to ultrapure iron concentrate powder is air-flow crushing or mechanically crushes,
Mechanical crush includes roll mill, vibromill or ball milling.
Further, in the step 1, the partial size after the ultrapure iron concentrate powder is crushed and classified is 1 μm~20 μm.
Raw material granularity is to influence the final highly important factor of iron particle size, because of the average particle size base of final superfine iron powder
This is consistent with the smashed average grain diameter of raw material, that is to say, that when the average particle size after raw material is crushed and classified is 5 μm, reduction
The granularity of superfine iron powder is also at 5 μm or so afterwards, therefore can reach control final products iron powder by controlling the granularity of raw material
The purpose of granularity.
Further, in the step 2, the ultrapure iron concentrate powder after being crushed and classified is heated to 300 DEG C in air
~450 DEG C, 1~2 hour is kept the temperature, Fe is obtained2O3Powder.
Further, in the step 3, Fe is restored in continuous reduction furnace2O3Powder.
Preferably, the continuous reduction furnace is to push away boat furnace or band oven.
Further, in the step 3, H is passed through in continuous reduction furnace2Or CO restores Fe2O3Powder, the H2Or
The direction of CO flowing and the Fe2O3Powder is run contrary.
Further, in the step 3, for reduction temperature between 600 DEG C~750 DEG C, recovery time range is 2~3h.
The present invention is fine granularity in order to keep final products in 600 DEG C~750 DEG C of at a temperature of reduction, because, temperature
The speed restored when too low is too slow, and the recovery time needed is too long, and the iron powder after restoring when temperature is too high is easy sintering, causes powder
The particle size growth at end, superfine iron powder not easy to produce.
Further, in the step 3, by Fe2O3Powder is fitted into single layer boat or the double-deck boat and is restored.
The number of plies of boat cannot be too many, and on the one hand being influenced the number of plies by burner hearth internal height cannot be too many, on the other hand, boat layer
Mostly, the processing technology of boat will be very troublesome for number, and fills powder in boat and powder is taken also to bother accordingly from boat, thus shadow
Ring the economy of production.
Preferably, in the step 3, by Fe2O3Powder is fitted into the double-deck boat and is restored.
Since the speed of reduction carries out being first to increase to reduce afterwards with reduction process, so that reduction process is in final stage
Very slowly, cause the utilization rate of reducing gas lower, so that production cost is increased, in order to solve this problem, side of the present invention
Method develops the restoring method of the double-deck boat, i.e., the double-deck boat is used in reduction apparatus, the bisque in every layer of boat is very thin, such as 5mm
Left and right, to improve the utilization rate of reducing gas, meanwhile, the double-deck boat can greatly improve yield, accordingly decrease unit of the product electricity
Consumption, hydrogen consumption, to reduce production cost, it is as follows why the double-deck boat can play the role of such main cause: (1) adopting
The contact area that hydrogen and powder are considerably increased with the double-deck boat is conducive to the progress of redox reaction；(2) also due to oxidation
Original reaction can output steam, and steam belongs to oxidizing atmosphere, so that redox reaction is difficult to carry out, and the double-deck boat is by burner hearth
Interior space is divided into two layers, and comparatively vapour quantity is reduced in each layer, is conducive to the progress of reaction.
Further, the double-deck boat includes upper layer boat, lower layer's boat and branch angle, and the branch angle is located at the upper layer boat under
Between layer boat.
Further, the branch angle has 4, and the one end at the branch angle is located at the edge of lower layer's boat, the branch angle
The other end be located at the edge of upper layer boat lower end.
Branch angle is used to support upper layer boat, prevents upper layer boat from tilting because unstable, causes the unrestrained of powder.
The present invention has the beneficial effect that:
(1) raw material ultrapure iron concentrate powder amount used in the present invention is inexpensive greatly, and the method for the present invention is simple, energy-saving and environmental protection,
And it can be with serialization, mass production superfine iron powder；
(2) present invention is oxidized to Fe by the way that first ultrapure iron concentrate powder is crushed and is classified2O3It restores and is surpassed after powder
Thin iron powder can be effectively reduced the partial size and oxygen content of prepared superfine iron powder；
(3) reduction process of the present invention burns boat using multilayer and charges, and can either improve the production efficiency of superfine iron powder, again
The utilization rate of reducing gas can be improved, there is industrial value.
Detailed description of the invention
Attached drawing is only used for showing the purpose of specific embodiment, and is not to be construed as limiting the invention, in entire attached drawing
In, identical reference symbol indicates identical component.
Fig. 1 is the shape appearance figure of ultrapure iron concentrate powder in the embodiment of the present invention 1；
Fig. 2 be the embodiment of the present invention 1 in ultrapure iron concentrate powder be crushed and classified after shape appearance figure；
Fig. 3 is Fe in the embodiment of the present invention 12O3The shape appearance figure of powder；
Fig. 4 is the shape appearance figure of superfine iron powder prepared in the embodiment of the present invention 1；
Fig. 5 is the shape appearance figure of superfine iron powder prepared in the embodiment of the present invention 1；
Fig. 6 is the shape appearance figure of superfine iron powder prepared in comparative example 1；
Fig. 7 is the top view of the double-deck boat of the present invention；
Fig. 8 is the main view of the double-deck boat of the present invention；
Fig. 9 is the left view of the double-deck boat of the present invention.
In figure, the upper layer 1- boat, 2- branch angle, 3- lower layer boat.
Specific embodiment
Specifically describing the preferred embodiment of the present invention with reference to the accompanying drawing, wherein attached drawing constitutes the application a part, and
Together with embodiments of the present invention for illustrating the principle of the present invention.
Embodiment 1
Step 1, ultrapure iron concentrate powder is poured into jet mill grinding machine carry out ultrapure iron concentrate powder air-flow crushing and point
Grade controls the granularity of ultrapure iron concentrate powder after crushing and classification by adjusting air-flow crushing and grading technology parameter, wherein this
The design parameter of air-flow crushing and classification in embodiment are as follows: pulverizer compressed air require is 10m3/ min, classifier impeller turn
Speed is 3 000r/min, and the average grain diameter of the ultrapure iron concentrate powder after being crushed and classified using above-mentioned parameter is 4.6 μm；It is ultrapure
The pattern that fine iron breeze is crushed and classified front and back is shown in that Fig. 1 and Fig. 2, Fig. 1 are that the pattern before ultrapure iron concentrate powder is crushed and classified shines
Piece, Fig. 2 are the pattern photo after ultrapure iron concentrate powder is crushed and classified, by figure can, it is evident that before being crushed and classified it is super
The particle size distribution of pure iron concentrate powder is very wide, existing very thin powder, also there is many very thick powder, than if any being much more than
20 μm of powder；After crushing and classification, the size distribution of ultrapure iron concentrate powder becomes extremely to concentrate, i.e., granularity is not much different,
Between 1-10 μm, and most of powder size concentrates on 4 μm or so.
Meanwhile the present invention is crushed and classified front and back to ultrapure iron concentrate powder and has carried out laser particle size analysis, as shown in table 1.
The mean particle size D 50 of ultrapure iron concentrate powder is 15.3 μm before being crushed and classified, and maximum powder partial size D90 reaches 41.1 μm, partial size
Powder D10 less than 4.5 μm only accounts for the 10% of total powder weight.And the ultrapure iron concentrate powder average grain diameter being crushed and classified
D50 is 4.6 μm, and maximum powder granularity has been reduced to 9.6 μm, illustrates that powder size becomes smaller and becomes after being crushed and classified
Granularity is concentrated.
1 ultrapure iron concentrate powder laser particle size analysis result of table
Ultrapure iron concentrate powder after being crushed and classified is put into Muffle furnace and carries out airoxidation by step 2, Muffle furnace
Temperature be set as 300 DEG C, oxidization time is 1 hour, obtains Fe2O3Powder, obtained Fe2O3The color of powder is in dark red
Color, Fe2O3Powder morphology as shown in figure 3, by Fig. 3, it can be seen that after heated oxide Fe2O3The granularity of powder relative to
Fe3O4It does not change significantly, also maintains the powder size of raw material；
Step 3, to Fe2O3Powder is restored, and reduction is carried out in continuous boat pushing furnace, the heading-length of the furnace
For 6m, cooling segment length is 7m, reducing gas H2, the effective dimensions of boat is 450mm × 450mm, and boat is placed on graphite pallet
(graphite pallet is having a size of 500mm × 500mm), to reduce the frictional resistance between boat and boiler tube bottom, the present embodiment is used
Boat be the double-deck boat, specifically: by Fe2O3Powder is put into the double-deck boat, and the upper and lower every boat of boat charges 600 grams, and the double-deck boat is put into company
Continuous formula pushes away in boat furnace, and reduction temperature is 720 DEG C, and pushing away the boat time is that 15min is pushed away once, Fe2O3Recovery time of the powder in high temperature section
For 3h, the flow of hydrogen is 12m3/ h, high temperature section of the present invention refer to bringing-up section；
Step 4, reduction terminate, and take out the double-deck boat, and superfine iron powder preparation is completed, and composition analysis result is as shown in table 2, shape
Looks are as shown in Figure 4,5；The superfine iron powder granularity restored after oxidation processes as can be seen from Figure is more tiny, and is sweeping
Retouching 2000 times of electron microscope (SEM) amplification can be clearly seen that the primary particle size of particle is respectively less than 5 μm, and primary grain
Combination between degree is also more open, primary particle size refer under the microscope it can be seen that, the granularity of smallest particles distinguished,
Second particle, particle as shown in Figure 4 are known as by the biggish particle that different number of primary particle is bonded together；It generates
The reason of above-mentioned phenomenon may be that fine iron breeze after oxidation processes can be abundant in lower temperature and shorter time
It is restored；This also illustrates ultrapure iron concentrate powder carrying out oxidation processes, makes its ingredient by Fe3O4Become Fe2O3, due to this two
The difference of the kind structure of matter, so that the process of reduction is easier to carry out, obtained superfine iron powder sintering activity is higher, more suitable for
The application of powder metallurgy product；
The method of the present invention must be such that some primary particles are bonded together, and be realized by suitable reduction temperature, because
If reduction temperature is too low, at such as less than 600 DEG C, the recovery time on the one hand needed is too long, high production cost, another party
Face, the primary particle after reduction does not have any bonding phenomenon, in this way since the tiny specific surface area of particle is very big, so that it holds very much
Easily cause spontaneous combustion in air oxidation fever, thus not easy to store.
The composition analysis result of 2 reduced iron powder of table
The present invention prepares comparative example 1 for embodiment 1, and comparative example 1 is that system is reduced directly after crushing ultrapure iron concentrate powder
Standby ultrapure iron powder, specific steps are as follows:
It is step 1, identical as the step 1 of embodiment 1；
Step 2 restores the ultrapure iron concentrate powder after being crushed and classified, reduction be in continuous boat pushing furnace into
Ultrapure iron concentrate powder after being crushed and classified is fitted into the double-deck boat by row, and the temperature of bringing-up section is disposed as 780 DEG C, every 15min
A boat is pushed away, can calculate material in high temperature section total recovery time is 3h, and the flow of hydrogen is 12m3/ h is filled in every boat and is crushed
With 600 grams of ultrapure iron concentrate powder after classification；
Step 3, reduction terminate, and take out the double-deck boat, and superfine iron powder preparation is completed, as shown in fig. 6, the iron powder after reduction
There is slight agglomeration, meanwhile, the ingredient of superfine iron powder is analyzed, as shown in table 3.
The composition analysis result of 3 superfine iron powder of table
It is compared by embodiment 1 and comparative example 1, all iron content of superfine iron powder is greater than the complete of comparative example 1 in embodiment 1
Iron content, meanwhile, the oxygen content of 1 superfine iron powder of embodiment is less than the oxygen content of superfine iron powder in comparative example 1；In addition, this implementation
The reduction temperature of example 1 significantly reduces, and therefore, the present embodiment 1 is relative to comparative example 1, by will be after ultrapure iron concentrate powder initial oxidation
Reduction, effectively reduces oxygen content in superfine iron powder, while reducing reduction temperature, so that production cost further decreases.
It is noted that the calculation method of recovery time are as follows: reduction furnace high temperature segment length (m)/(60min/ pushes away the boat time
(min) length of * boat)=6/ (60/15*0.5)=3h, for the double-deck boat, time of every boat in reduction furnace must reach 3h,
Otherwise standard requirements are not achieved in the oxygen content after restoring；But for Fe2O3Reduction temperature can suitably reduce, embodiment 1
In use 720 DEG C of reduction temperature, and by Fe in comparative example 13O4The temperature of direct-reduction must then can be only achieved at 780 DEG C
It is required that.
It is noted that the present invention prepares superfine iron powder using the double-deck boat, hydrogen can be made full use of, be saved
The usage amount of reducing gas, while the oxygen content of superfine iron powder is improved, there is important industrial application value.
Embodiment 2
The present invention is that initial oxidation is Fe after crushing ultrapure iron concentrate powder2O3, then direct-reduction prepares ultrapure iron powder, but
Boat used in its reduction process is single layer boat, specific steps are as follows:
It is step 1, identical as the step 1 of embodiment 1；
It is step 2, identical as the step 2 of embodiment 1；
Step 3, by Fe2O3Powder is put into single layer boat, and single layer boat charges 600 grams, and reduction temperature is 720 DEG C, pushes away the boat time
It is pushed away once for 10min；
Step 4, reduction terminate, and take out single layer boat, and superfine iron powder preparation is completed, the partial size of prepared superfine iron powder
Uniformly, average grain diameter is less than 5 μm.
The present invention prepares comparative example 2 for embodiment 2, and comparative example 2 is that the double-deck boat for using 1 reduction process of comparative example changes
For single layer boat, specific steps are as follows:
It is step 1, identical as the step 1 of embodiment 1；
Step 2 restores the ultrapure iron concentrate powder after being crushed and classified, reduction be in continuous boat pushing furnace into
Row, the ultrapure iron concentrate powder after being crushed and classified is fitted into single layer boat, the temperature of bringing-up section is disposed as 780 DEG C, every 10min
A boat is pushed away, can calculate material in high temperature section total recovery time is 2h, and the flow of hydrogen is 12m3/ h is filled in every boat and is crushed
With 600 grams of ultrapure iron concentrate powder after classification；
Step 3, reduction terminate, and take out single layer boat, and superfine iron powder preparation is completed.
It is compared by embodiment 2 and comparative example 2, reduction temperature reduces in embodiment 2, the oxygen of prepared superfine iron powder
Content reduces.
It is noted that the calculation method of 2 recovery time of the present embodiment: reduction furnace high temperature segment length (m)/(60min/ is pushed away
The length of boat time (min) * boat)=6/ (60/10*0.5)=2h, it is high from entering that every boat powder can be calculated for single layer boat
Temperature section is 2h to the high temperature section time experienced out, and for the double-deck boat, every 15min pushes away a boat, and is identical stove, phase
Same boat, only becomes upper layer and lower layer boat, the amount of powder in every boat is also identical, so the time that each boat is undergone in furnace is
6/ (60/15*0.5)=3h can produce qualified product in such a situa-tion, but for the double-deck boat yield compared with single layer
Boat improves 33%.
It is noted that the thickness for filling powder in boat influences whether the reduction situation of powder, therefore, boat used in the present invention
The thickness control of middle dress powder can guarantee the efficiency and Fe that fill powder in 5mm in this way2O3Sufficiently reduction.
It is noted that the recovery time of the present invention is longer, reduction temperature is higher, this is because institute in the present invention
Oxygen content≤0.5% in the superfine iron powder of production, because this is minimum oxygen for the iron powder of powder metallurgy industry
Content requirement, powder metallurgy industry iron powder wishes that the lower its oxygen content the better, because oxygen can hinder metallic sintered products being sintered
Densification in the process, to influence the intensity of metallic sintered products；And according to the reduction mechanism of iron oxide it is recognised that more arriving also
Former final stage, reduction process carry out slower, so the recovery time that the present invention uses is longer, reduction temperature is higher, with
Ensure that the oxygen content in final reduced iron powder reaches requirement.
It is noted that the present invention also proposed to improve the utilization rate of hydrogen as far as possible using the double-deck boat, because
During the gas reduction of iron oxide, the actual flow of reducing gas often beyond restoring 5~10 times of tolerance needed for theory,
That is the utilization rate of also Primordial Qi is very low, so improving the utilization of also Primordial Qi the invention proposes the method for the double-deck boat
Rate, to reduce production cost.
As shown in figs. 7-9, including upper layer boat 1, lower layer's boat 3 and branch angle 2, branch angle 2 are located at bilayer boat used in the present invention
Between upper layer boat 1 and lower layer's boat 3, it is used to support upper layer boat 1, guarantees the stabilization of upper layer boat 1；Branch angle 2 has 4, is column, rectangular
Body, square shape, 4 branch angles 2 are located on four angles of lower layer's boat 3, and the one end at branch angle 2 and the bottom surface of upper layer boat 1 are solid
Fixed connection, the other end at branch angle 2 are fixedly connected with lower layer boat 3；Upper layer boat 1 is identical as lower layer's 3 structures of boat, is removal upper surface
Square or cuboid.
It is noted that upper layer boat 1 will not shake or move when branch angle 2 can guarantee to push away boat, while guaranteeing upper layer
Charge in boat 1 and lower layer's boat 3 is same, these advantages can guarantee the raising of production efficiency.
It is noted that the double-deck boat is stainless steel boat, and material SUS310s, with a thickness of 3mm, upper layer boat 1 and roof of the furnace
Distance and upper layer boat 1 it is equal with the distance between lower layer boat 3, preferably the distance between upper layer boat 1 and lower layer's boat 3 be 20~
30mm, most preferably distance are 20mm.
It is noted that bilayer boat structure very simple of the present invention, easily carries out upper layer boat under in this way
The loading and unloading work of layer boat, convenient for improving working efficiency；As long as the application guarantees the spacing between upper and lower level boat, so that it may guarantee
Hydrogen flowing quantity is essentially identical between upper and lower boat, to guarantee that the reduction effect of material in boat up and down is consistent, without by special
Boat structure guarantee the identical of hydrogen flowing quantity state.
In conclusion the present invention provides a kind of method that low cost low temperature direct-reduction prepares superfine iron powder, pass through by
Fe is oxidized to after ultrapure iron concentrate powder crushing and classification2O3, then carry out reduction and prepare superfine iron powder, obtain tiny ultra-fine of granularity
Iron powder, meanwhile, using the double-deck boat in reduction process, effectively increase the utilization efficiency of hydrogen；Had using the method for the present invention
Ultrapure iron concentrate powder former material doses is inexpensive greatly, and technical process is simple, energy-saving and environmental protection, and can with serialization, produce in enormous quantities it is ultra-fine
The features such as iron powder.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by anyone skilled in the art,
It should be covered by the protection scope of the present invention.
Claims (4)
1. a kind of method that low cost low temperature direct-reduction prepares superfine iron powder, which is characterized in that mainly comprise the steps that
Ultrapure iron concentrate powder is crushed and is classified by step 1, the ultrapure iron concentrate powder after being crushed and classified；
Step 2 is aoxidized to obtain Fe to the ultrapure iron concentrate powder after being crushed and classified2O3Powder；
Step 3, using reducibility gas by Fe2O3Powder is restored；
Step 4, reduction terminate, and superfine iron powder preparation is completed；
In the step 1, the breaking method to ultrapure iron concentrate powder is air-flow crushing or mechanical crushing, the mechanical crushing
Including roll mill, vibromill or ball milling；
In the step 1, the partial size after the ultrapure iron concentrate powder is crushed and classified is 1 μm~20 μm；
In the step 2, the ultrapure iron concentrate powder after being crushed and classified is heated to 300 DEG C~450 DEG C in air, heat preservation 1
~2 hours, obtain Fe2O3Powder；
In the step 3, by Fe2O3Powder is packed into the double-deck boat and is restored, and reduction temperature is between 600 DEG C~750 DEG C, reduction
Time range is 2~3h；
The bilayer boat includes upper layer boat, lower layer's boat and branch angle, and the branch angle is between the upper layer boat and lower layer's boat；
The superfine iron powder being prepared is used for field of powder metallurgy.
2. the method that a kind of low cost low temperature direct-reduction according to claim 1 prepares superfine iron powder, which is characterized in that
In the step 3, Fe is restored in continuous reduction furnace2O3Powder.
3. the method that a kind of low cost low temperature direct-reduction according to claim 2 prepares superfine iron powder, which is characterized in that
In the step 3, H is passed through in continuous reduction furnace2Or CO restores Fe2O3Powder, the H2Or CO flowing direction with it is described
Fe2O3Powder is run contrary.
4. the method that a kind of low cost low temperature direct-reduction according to claim 1 prepares superfine iron powder, which is characterized in that
The branch angle has 4, and the one end at the branch angle is located at the edge of lower layer's boat, and the other end at the branch angle is located on described
The edge of layer boat lower end.
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| CN110773749A (en) * | 2019-11-19 | 2020-02-11 | 河北林松金属粉末科技有限公司 | Method for preparing superfine iron powder by rapid direct reduction |
| CN110842211A (en) * | 2019-12-17 | 2020-02-28 | 云南驰宏国际锗业有限公司 | Method for controlling particle size of superfine germanium powder |
| CN113458406B (en) * | 2021-06-29 | 2022-09-30 | 河北林松金属粉末科技有限公司 | Method for quickly producing superfine iron powder |
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