JPS63140041A - Recarburized iron and its preparation - Google Patents

Abstract

PURPOSE:To prevent pulverization, moisture absorption and oxidation of porous iron and to produce recarburized iron for adjusting the carbon content of reduced iron, etc., by spraying a thermoplastic resin contg. a carbon source to the surface of the porous iron held at an adequate temp. and thereby coating said iron. CONSTITUTION:A rotary drum 1 having vanes 4 for agitation and a heater 9 is supported and rotated by a rotary supporting base 3 having a motor 2. The porous iron such as reduced iron pellets or lump iron ore is supplied by a feeder 7 to the drum 1. A molten thermoplastic resin contg. a carbon source is sprayed onto the surface of the above-mentioned porous iron by a heating sprayer 8. The porous iron is held at the temp. higher by about 10 deg.C than the softening temp. of said thermoplastic resin at this time. The iron may be heated to the softening temp. of the resin or above if desired after the above-mentioned spraying. Carbon powder, carbon black and coke powder having <=100mum grain size are used for said carbon source and the content of <=30wt% is more adequate. As the above-mentioned resin, a polyolefin resin such as PE and PP is appropriate.

Description

[Detailed description of the invention] Distributing chestnuts, packaging, melons, public and private The present invention relates to carburized iron and its manufacturing method.

When using reduced iron to produce steel products, a carbon source is added as a reducing agent to reduce the coexisting iron oxide when melting the reduced iron in an electric furnace. There is. As a carbon source, natural gas is used in the Hill method, Midrex method, Lyall method, etc., and coal is used in the Lurgi method, Kurzub method, I)nC method, and Kingroll-Metzter method. In the former case, the carbon content in the reduced iron is approximately 1.0-2.5% by weight, and in the latter 0.1-0.5% by weight. Generally, the amount of reducing agent is required to be about 2.0% based on the reduced iron, so it is actually necessary to further add carbon to the molten iron to adjust the carbon amount.

However, in the method of adding carbon directly to molten iron, the difference in specific gravity between carbon and iron is significant, so carbon floats to the surface and is oxidized on the surface and is consumed as carbon dioxide gas, which does not produce a sufficient reducing effect. There was a problem in that it was difficult to disperse uniformly.

On the other hand, porous iron such as reduced iron pellets and lamp iron ore is porous and brittle, easily pulverized by friction between iron lumps, absorbs moisture, or comes into contact with water or air.
The problem is that it is easily oxidized.

Means for Solving the Problems The present invention coats the surface of porous iron with a thermoplastic resin containing carbon powder to prevent the porous iron from becoming pulverized, absorbing moisture, and oxidizing. , which provides a way to adjust the carbon content.

That is, the present invention relates to carburized iron in which a porous iron surface is coated with a thermoplastic resin containing a carbon source, and a method for producing the same.

The carbon source used in the present invention is preferably carbon powder, such as coal powder, carbon black, coke powder, charcoal, petroleum pitch, petroleum coke, anthracite, electrode graphite scrap, graphite slap, waste carbon black, electrode graphite scrap, etc. For example, as an inexpensive raw material, there is fine coke, which is a by-product of coke obtained by a cold breeze method.

The particle size of carbon powder is 100 when applied by spray method etc.
μ! Hereinafter, in the case of the dipping method, a thickness of 1 mm or less is appropriate.

It is preferable that the carbon source accounts for 30% by weight or less of the total amount of the thermoplastic resin and carbon source, and if it exceeds 30% by weight, the coating film strength will decrease.

Examples of the thermoplastic resin used in the present invention include polyolefin resins such as polyethylene, borine [1-pyrene, polybutylene, and methylpentene, ethylene-vinyl acetate copolymer, and ethylene-ethyl (methyl) acrylate copolymer]. Olefin copolymer; poly-p-xylylene,
Polyvinyl acetate, polyacrylate, polymethacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl ether, polyacrylonitrile, thermoplastic polyester, polycarbonate, polybutadiene, polyi is polyolefin, polyolefin copolymer resin, vinyl acetate, etc., and polyolefin , particularly polyethylene.

These resins have a viscosity of 1 to 1000 at 200°C.
0cps, especially 10-7000cps, softening temperature 60
~200°C, particularly about 80~120°C is suitable.

If the viscosity of the thermoplastic resin is greater than 10,000 cps,
In addition to non-uniform mixing with the carbon source, the surface of the porous iron is not evenly coated, and the moisture absorption prevention effect of the resin coating is reduced. If the resin viscosity is less than l cps, the resin will be absorbed into the pores of the iron surface, so a large amount of resin will be required.

In the present invention, a recovered film of agricultural polyethylene, low-molecular In polyethylene which is a by-product of the polyethylene manufacturing process, active polypropylene, etc. can be used, and these may be used by mixing them in an appropriate ratio. When using active polypropylene, the carbon content can be increased to ζ7. - As porous iron, reduced iron pellets (porosity approximately 50%
), reduced iron briquettes obtained by hot compression (porosity: 20-30%), lamp iron ore (porosity: approximately 5
0%), etc., and these are usually used in the form of blocks of about 3 to 40 mm.

There are two methods of coating a porous iron surface with a carbon source-containing thermoplastic resin: a spray method and a dipping method. 1-, which causes surface rejuvenation, is preferred.

In the spray method, a thermoplastic resin in which a carbon source is dispersed is atomized, and the mist is sprayed onto a porous cooking surface maintained at a temperature lower than the softening temperature of the resin.

The mist may be either a molten resin mist or a powdered mist, but the particle size is preferably 100 μm or less. The sprayed mist, even if it is a molten mist, solidifies on the iron surface. As a result, the resin is not impregnated into the voids of the porous outer iron, and is effective in coating the surface with a small r+1. Therefore, the surface temperature of the porous outer iron and the like is preferably lower than the softening temperature of the resin, and is generally between room temperature and about 80°C. Since reduced iron pellets are usually obtained at 50 to 60°C, they can be used as they are.

The amount of carbon-containing thermoplastic resin attached to the porous outer iron is 1
Carbon-containing (T!A plastic resin 0.1~
4 parts by weight are suitable, especially 0.5 to 3 parts by weight. 0.1
If it is less than 4 parts by weight, the coating thickness will be insufficient, and if it is more than 4 parts by weight, it will only become uneconomical.If the method of the present invention is adopted, the porous outer iron can be uniformly coated with a small amount of resin as described above. can be coated with

The porous outer iron obtained by the above method has a carbon-containing thermoplastic resin mist attached to its surface, and many uncoated parts remain on its surface.

Therefore, the resin-coated young porous irons are brought into rotational contact with each other in a suitable rotating body to uniformly apply the resin to their surfaces. At this time, the temperature of the processing atmosphere is preferably maintained at a low temperature, particularly at a temperature lower than the softening temperature of the resin. By doing this, there is no risk that the iron surface not coated with resin will be exposed to high temperatures and oxidized, and in addition, the resin will not be impregnated into the voids of the porous outer iron more than necessary and consumed. . As a result, there is no need to carry out the processing in an inert gas atmosphere, making continuous processing easier and the structure of the processing apparatus simpler.

The carbon-containing resin-coated porous iron obtained by the above method has sufficient oxidation resistance as it is, has low water absorption, and is difficult to turn into dust. However, if necessary, the coated porous iron can be further coated with resin. It may be heated above the softening temperature. In this case, since the porous outer iron is coated with resin, oxidation due to heating can be prevented.

Post-heating is preferred in order to achieve the density and uniformity of the resin.

When this method is employed, it is preferable to use powdered coal of 100 μm or less as the carbon source. ! If it exceeds 00μ, clogging of the spray nozzle may occur.

An example of a method for manufacturing porous outer iron coated with a carbon-containing thermoplastic resin by the above-mentioned spray method will be described below with reference to FIGS. 1 to 11.

Fig. 2 is a left side view of the device in Fig. 1, and Fig. 3 is a left side view of the device shown in Fig. 1. -1 sectional view and FIG. 4 show a right side view. A cylindrical horizontal rotating drum (1) is rotatably installed on a rotating support (3) rotated by a motor (2),
There is a supply port (5) on the left side of the drum for supplying porous outer iron.
) and a heating spray device are provided, and a discharge port (6) for discharging the porous outer iron is provided on the right side of the drum. In order to use a continuous manufacturing method (one-way overflow method), the discharge port should be larger than the supply port, and the discharge port (
The height e) up to 6) may be made smaller than the height Qo) up to the supply port. A vane (4) is provided inside the drum.

A certain amount of porous outer iron and a carbon-containing thermoplastic resin to cover it are charged from the supply port by heating spray, and the drum 11 is rotated.Since the rotation of the porous outer iron is hindered by the blades, it does not fit well with each other. The resin contacts and is pressed by the co-rubbing effect, and the resin adheres uniformly.At that time, the porous iron surface is heated to the temperature of the wood (11) by climbing onto the heater (9). t, upper - resin coating of porous iron is 2
It may be done in a process.

That is, a porous iron surface coated with a carbon-containing thermoplastic resin in the same manner as described above is then heated, if necessary. In this case, since the resin film is formed in the first step, reoxidation due to heating can be suppressed.

The porous iron surface coated with the carbon-containing thermoplastic resin in the same manner as above may be further coated with the carbon-containing thermoplastic resin by repeating the same operation as the second step. At that time, the resin used in the first step and the resin used in the second step may be different. For example, in the first step, a resin that is difficult to impregnate into the porous iron surface, such as a thermoplastic resin with a molecular weight of about 5000, is used.
A resin having a molecular weight of about 1500 may be used in the second step. Further, a resin with high wear resistance may be used in the second step.

This second step does not necessarily need to employ the above method, and may also employ a dipping method. In this case, since the resin coating is formed in the first step, penetration of the resin into the porous iron due to immersion can be suppressed.

However, in such a case, conditions should be adopted so that the resin coating formed in the first step does not dissolve again.

As mentioned above, in the spray method, carbon-containing material is added to the porous iron surface.
This makes it possible to apply uniformly while suppressing resin absorption as much as possible, and also to supply carburized iron without causing oxidation, powdering, tearing, etc.

The second method of the present invention is a dipping method. With the above spray method, it is possible to carburize 6 degrees without actively suppressing the absorption of resin into porous iron, but it is necessary to carburize pig iron, steel, soft iron, etc., which require a large amount of carburization. Preferably, the carburized iron itself contains a large carbon source. A dipping method can be used for that purpose.

In the immersion 11 method, a low viscosity resin is melted and a carbon source is dispersed therein. As the carbon source, it is preferable to use carbon powder of about 1 mm or less. The particle size of carbon powder is 1IllI1
If it is larger than 1, the carbon powder itself becomes a source of dust due to friction and collision of porous iron during handling and transportation.

Porous iron is immersed in this carbon-containing aqueous resin liquid, then pulled out and cooled if desired.

The present invention will be explained below using examples.

Hitane carp 1 Reduced iron pellets preheated to 75℃ (
As shown in Figure 1, the porosity is 55% and the water absorption rate is 15%.
A fixed amount is continuously supplied from the supply device (7) to the rotating drum (+
) and carbon black (particle size 50 μm)
20% by weight mixed resin (molecular weight 1400, softening point 8
34% by weight of polyethylene resin at 3°C, 34% by weight of active polypropylene resin with a softening point of 110°C, and 12% by weight of high molecular weight polyethylene resin with a molecular weight of 330,000 and a softening point of 86°C) were heated in a heating spray device (8). While continuously supplying the mixture to a liquid mist at a rate of 2% by weight relative to the pellets, the inner wall of the drum was heated to 180° C. by a drum heater (9), and carburized iron was obtained using a rotary overflow method. The obtained carburized iron was released outdoors for 1 month at 11 vol.
L, changes in metallization rate, water absorption rate during rainfall and one rotation strength were observed. The results are shown in Table-1.

Measured by analysis.

Water absorption rate: Calculated by exposing sample 1009 for 5 hours during rainfall of average rainfall m2IllllI/■, and immediately weighing after absorbing the water adhering to the surface to the filter paper.

Rotational strength: Calculated rotational strength index and abrasion strength index based on J 15-M-8712.

Example 2 Reduced iron pellets heated to 75°C in advance (
A fixed amount of carbon black (particle size: 50 μm) and a mixed resin containing 20 wt.
Molecule m1400. Polyethylene resin 34 with a softening point of 83°C
Weight% and softening point! Aqueous polypropylene resin (34% market weight at 10°C and high molecular weight polyethylene resin (12% by weight, molecular weight 330,000, softening point 86°C)) was heated and sprayed into a liquid mist, and 4% by weight was added to the pellets.
llk1shi^a+-41tob~1-x-1V-J), +
Big+I! L? -I011'/'', rotated, and obtained carburized iron by one overflow method.The obtained carburized iron was left outdoors for one month, and changes in metallization rate, water absorption rate during rain, The rotational strength was observed.The results are shown in Table-1.

Kanshi carp Reduced iron pellets preheated to 75℃ (
A fixed amount of the mixed resin (porosity 55%, water absorption rate 15%) containing 30% by weight of carbon black (particle size 50 μm) was continuously charged into a rotating drum in the same manner as in Example 1.
Molecule fill 400. 30% by weight polyethylene resin with a softening point of 83°C, 30% by weight of an active polypropylene resin with a softening point of 110°C, a molecular weight of 330,000, and a softening point of 86°C.
A high molecular weight polyethylene resin (10% by weight) was made into a liquid mist by heating spray, and while continuously feeding the pellets at a rate of 2% by weight, the inner wall of the drum was heated to 180°C, the drum was rotated, and the overflow [1 Carburized iron was obtained by one method. The obtained carburized iron was left outdoors for one month,
Changes in metallization rate, water absorption during rainfall, and rotational strength were observed. The results are shown in Table-1.

Comparative Example 1 Reduced iron pellets heated to 75°C in advance (
A fixed amount of porosity 55%, water absorption 15%) was continuously charged into a rotating drum in the same manner as in Example 1, and mixed resin (42.5% by weight of polyethylene resin with molecules m 1400 and a softening point of 83°C) 42.5% by weight of an active polypropylene resin with a softening point of 110°C and a polymer with a molecular Rik of 330,000 and a softening point of 86°C...polyethylene resin 15tfffn
%) was made into a liquid mist by heating spray, and while continuously supplying the mixture at a ratio of 2% by weight to the pellets, the drum l and inner wall were heated to 180° C. and rotated. Carburized iron was obtained using the overflow method, and the obtained carburized iron was left outdoors for t months to observe changes in metallization rate, water absorption during rain, and rotational strength. The results are shown in Table-1.

Comparative Example 2 Reduced iron pellets heated to 75°C in advance (
Porosity: 55%, water absorption: 15%) was continuously charged into a rotating drum in a fixed amount in the same manner as in Example 1, and mixed resin containing 40% by weight of carbon black (particle size: 50μ) (molecular weight: 1400, softening point) 83℃ polyethylene resin 25.5
Weight% and softening point! Acrylic polypropylene resin 25° 5% by weight at 10°C, molecular fi'i 330,000, softening point 86
Polymer at °C! The inner wall of the drum was heated to 180° C. and rotated while continuously supplying a liquid mist (9% by weight of n-polyethylene resin) to the pellets at a ratio of 2% by weight to the pellets. Carburized iron was obtained by one overflow method, and the obtained carburized iron was left outdoors for one month to observe changes in metallization rate, water absorption rate during rain, and rotational strength. The results are shown in Table-1.

Comparative Example 3 Uncoated reduced iron pellets were left outdoors for one month, and changes in metallization rate were observed, as well as water absorption during rain and rotational strength. The results are shown in Table-I.

Oijimaji ↓ Lamp iron ore (porosity 50%, water absorption rate 9.6%) that had been heated to 75°C in advance was continuously charged into a rotating drum in a fixed amount in the same manner as in Example 1. This contains 20% by weight of carbon black (particle size 50 μm) (f mixed resin (
34% by weight of a polyethylene resin with a molecular weight of 400 and a softening point of 83°C, 34% by weight of an active polypropylene resin with a softening point of IIO°C, and 12% by weight of a high molecular weight polyethylene resin with a molecular weight of 330,000 and a softening point of 86°C) were heated and sprayed. A liquid mist was produced by heating the inner wall of the drum to 180° C. and rotating while continuously supplying the mixture to the lamp at a ratio of 11% double weight. Carburized iron was obtained by one overflow method, and the drop strength of the obtained carburized iron was evaluated. Table 2 of the results
Shown below.

Falling strength: Calculate the falling strength (%) by % Example 5 Lamp iron ore preheated to 75°C (porosity 50%, water absorption 9.6%) ) was continuously added to a rotating drum in a fixed amount in the same manner as in Example 1, and a mixture of carbon black (particle size 50 μm) containing 20% by weight (T mixed resin (
Polyethylene resin 34 with molecule m+4oo and softening point 83°C
Actic volip with weight% and softening point of 110°C
High polymer lit polyethylene resin! Double! n%) was made into a liquid mist by heating spray, and the amount was 4% by weight based on the lamp.
The inner wall of the drum was heated to 180° C. and rotated while being continuously supplied at a rate of . Carburized iron No. 12 was obtained using the overflow method, and the drop strength of the obtained carburized iron was evaluated. The results are shown in Table-2.

Example 6 Lamp iron ore (porosity 50%, water absorption rate 9.0%) that had been heated to 75°C in advance was continuously charged into a rotating drum in a fixed amount in the same manner as in Example 1. Carbon black (particle size 50μm) 30wt h1% a mixed resin (
Molecule m1400. Polyethylene resin 30 with a softening point of 83℃
30% by weight of an active polypropylene resin with a softening point IIθ°C and 10% by weight of a high molecular weight polyethylene resin with a molecular h of 1,330,000 and a softening point of 86°C) was made into a liquid mist by heating spraying, and 2% by weight was applied to the lamp. The inner wall of the drum is heated to 180°C while being continuously supplied at a certain rate,
Rotated. Obtain recarburized iron by one overflow method,
The drop strength of the obtained carburized iron was evaluated. The results are shown in Table-2.

Anonymous carp ↓ Lamp iron ore (porosity 50%, water absorption rate 9.6%) that had been heated to 75°C in advance was continuously introduced into a rotating drum in a fixed amount in the same manner as in Example 1. This is mixed with resin (molecule fn 1400. 42.5% by weight of polyethylene resin with a softening point of 83°C, 42.5% by weight of an acidic polypropylene resin with a softening point of 110°C, and a high molecular weight polyethylene resin with a molecule h of 1,330,000 and a softening point of 86°C. 15% by weight) is made into a liquid mist by heating spray, and double layered on the lamp! R
While continuously supplying at a rate of %, the inner wall of the drum was heated to 180℃
heated and rotated. Overflow was evaluated in one way. The results are shown in Table-2.

Comparative Example 5 A constant amount of lamp iron ore (porosity 50%, water absorption 9.6%) heated to 75°C in advance was continuously charged into a rotating drum in the same manner as in Example 1. Mixed resin containing 40% by weight of carbon black (particle size 50 μm) (molecular fit 1400, polyethylene resin 2 with a softening point of 83°C)
25.5% by weight of an active polypropylene resin with a softening point of 110°C and 9% by weight of an active polypropylene resin with a molecular weight of 1.33 million ff and a softening point of 86°C) was made into a liquid mist by heating spray and applied to a lamp. Against double 111
While continuously supplying at a rate of %, the inner wall of the drum was heated to 180℃
heated and rotated. Carburized iron was obtained by one overflow method, and the drop strength of the obtained carburized iron was evaluated. The results are shown in Table-2.

Comparative Example 6 The falling strength of uncoated lamp iron ore was observed. Display the results -
Shown in 2.

Table 2 Effects of the Invention The carburized iron of the present invention has its surface coated with resin, making it difficult for the porous iron to be pulverized during transportation. The carbon content can be adjusted to an appropriate level by blending it with other iron having a low carbon content. In addition, since carburized iron itself has a considerable specific gravity, it is easy to mix uniformly even when added to molten iron (it does not disappear on the surface of molten iron and is effectively used). This makes it difficult for the resin to be absorbed into the porous iron, and the porous iron can be coated with a small amount of resin.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the apparatus for continuously producing reduced iron pellets of the present invention, Fig. 2 is a left side view of the apparatus shown in Fig. 1 (reduced iron pellet supply port), and Fig. 3 is a sectional view along I-1 and Figure 4 shows the right side view (reduced iron pellet discharge port). (+) Rotating drum, (2) motor, (3) rotating support, (4) blade, (5) supply port,
(6) Discharge port, (7) Continuous reduced iron pellet supply device, (8) Heating spray device, (9) Drum heater.

Claims (1)

[Claims] 1. Carburized iron in which a porous iron surface is coated with a thermoplastic resin containing a carbon source. 2. Carburized iron according to item 1, wherein the carbon source is coal powder, carbon black, or coke powder. 3. Carburized iron according to item 1, wherein the thermoplastic resin is a polyolefin resin. 4. The first carbon content in the coating component is 30% by weight or less
Carburized iron as described in section. 5. Carburized iron according to item 1, wherein the porous iron is reduced iron pellets or lamp iron ore. 6. Spray the molten thermoplastic resin onto a porous iron surface held at a temperature below about 10°C above the softening temperature of the thermoplastic resin containing a carbon source, and if desired, use this to soften the resin. A process for producing carburized iron that involves heating it above temperature. 7. The method for producing carburized iron according to item 6, wherein the carbon source is coal powder, carbon black, or coke powder. 8. The manufacturing method according to item 6, wherein the carbon source has a particle size of 100 μm or less. 9. The method according to item 6, wherein the thermoplastic resin is a polyolefin resin. 10. The method according to item 6, wherein the carbon content in the coating component is 30% by weight or less. 11. The method according to item 6, wherein the porous iron is reduced iron pellets or lamp iron ore. 12. A method for producing carburized iron by impregnating porous iron in a thermoplastic resin liquid containing a carbon source to form a carbon-containing film on the iron surface. 13. The method according to item 12, wherein the carbon source is coal powder, carbon black, or coke powder. 14. The manufacturing method according to item 12, wherein the carbon source has a particle size of 1 mm or less. 15. 12th thermoplastic resin is polyolefin resin
Manufacturing method described in section. 16. The method according to item 12, wherein the carbon content in the coating component is 30% or less. 17. The method according to item 12, wherein the porous iron is reduced iron pellets or lamp iron ore.