JP2000176306A - Method for recovering oil by magnetic separation and magnetic body for oil recovery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover oil floating on water surface. SOLUTION: Heavy oil 2 floating on sea water 1 is recovered by dispersing a magnetic body 3, and magnetically separated by a recovery apparatus 5 mounted on a recovery ship 4. The magnetic body 3 is provided with heightened affinity for the heavy oil 2 by coating the surface of a fine particle of magnetite 10 with a hydrophobic coating of stearic acid 11. The magnetic attractive force of the recovery apparatus 5 to the magnetite 10 affects also the heavy oil 2 through the stearic acid 11, and sea water 1 and the heavy oil 2 are efficiently separated by magnetic force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil recovery method by magnetic separation for recovering oil floating on the surface of water, such as heavy oil which has flown into the ocean or the like, and a magnetic material for oil recovery.

[0002]

2. Description of the Related Art Conventionally, when various oil components flow into the sea, rivers, lakes and marshes, drains in urban areas, etc., they are promptly collected to prevent environmental pollution and fire. However, if heavy oil spills into the ocean due to, for example, a ship accident, it will have a serious environmental impact, but heavy oil that has spread thinly over a wide sea surface has no effective recovery means, At present, people rely on methods such as picking up with a ladle or absorbing with an oil absorbent or the like.

[0003] As a prior art relating to recovery of oil spilled on the sea surface or the like, for example, Japanese Patent Application Laid-Open No. 51-97589 is known
And Japanese Patent Application Laid-Open No. 63-42751 propose that oil is recovered using magnetic force. JP-A-51-975
In 89, a magnetic substance is disposed on a lipophilic substance such as foamed polypropylene, and an oil-water separating agent having magnetism is formed. The oil-water separating agent is floated on the water surface to adsorb the oil on the surface, and the oil-water separating agent is attracted by magnetic force. Prior art for recovering oil by using a conventional technique has been disclosed. In the prior art disclosed in JP-A-63-42751, a polymer having affinity for oil carries a magnetic substance, and the polymer carrying the magnetic substance captures the oil. The oil is recovered by aspiration. Fine particles such as magnetite having an average particle diameter of 20000 ° or less are dispersed in the polymer to impart magnetism.

The Chemical Society of Japan, No. 56, 1998, No. 8,
On pages 3 to 565, a bulletin titled "Adsorption treatment of heavy oil using expanded graphite" at the 74th Annual Meeting of the Chemical Society of Japan in March 1998 is published. According to this preliminary report, expanded graphite adsorbs oil and can swell greatly in the form of an accordion. By absorbing oil due to capillary action in the gap and adsorbing oil on the graphite surface, the expanded graphite is 80 times or more its own weight. The oil can be selectively adsorbed.

[0005]

As described above, for example, for recovery of heavy oil spilled into the ocean, a method using magnetic separation or expanded graphite has been proposed, but an effective oil recovery method has been established. Absent. JP-A-51-97
If the prior arts such as 589 and JP-A-63-42751 are effective, for example, even in the case of enormous damage along the coast of the Sea of Japan due to heavy oil spill of the Nakhodka sank off the coast of San-in in January 1997, The reduction should have been possible. The method using the selective adsorption characteristics of expanded graphite can also avoid the situation where heavy oil etc. spreads thinly on the sea surface due to adsorption, but the large amount of spillage in accidents such as large tankers can be avoided. A method for efficiently recovering heavy oil and the like has not been established yet. For this reason, at present, it takes a lot of time and effort to collect as much heavy oil as possible,
The remaining heavy oil spreads thinly, leaving it to the natural purifying action.

SUMMARY OF THE INVENTION An object of the present invention is to provide an oil recovery method by magnetic separation and a magnetic material for oil recovery that can efficiently recover heavy oil spilled into the ocean or the like by using a magnetic separation method.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for recovering oil floating on the surface of water, which comprises dispersing fine particles of a magnetic material having a surface subjected to a hydrophobic treatment into oil on the surface of water, This is an oil recovery method by magnetic separation, wherein magnetism is imparted to oil through a magnetic material, and the magnetic material is attracted by a magnetic force to recover the oil.

[0008] According to the present invention, the oil floating on the water surface
Sprinkle fine particles of magnetic material with hydrophobic treatment on the surface,
Since magnetism is imparted to the oil and separated from the water by the magnetic force, the magnetic force acts on the oil through the fine magnetic material, and the oil can be adsorbed by the magnetic force and efficiently collected. Since the surface of the magnetic material of the fine particles is subjected to a hydrophobic treatment, the affinity of the magnetic material of the fine particles is larger in oil than in water. Since the bond between the magnetic substance and oil is strengthened by hydrophobic interaction, the magnetic substance does not disperse in water and is not lost. can do.

Further, the present invention relates to a method for recovering oil floating on a water surface, wherein an inorganic porous material containing expanded graphite containing a magnetic substance is sprayed on the oil on the water surface to absorb the oil. And an oil recovery method by magnetic separation, wherein the oil is recovered by magnetically attracting the inorganic porous material that has absorbed the oil.

According to the present invention, an inorganic porous material containing expanded graphite containing a magnetic material therein is sprayed on oil on the water surface,
Oil can be adsorbed on the inorganic porous material. Since a magnetic material is contained in the inside of the inorganic porous material containing expanded graphite, if a magnetic force is applied, the attractive force is applied to the inorganic porous material when the magnetic material is attracted by the magnetic force. The oil can be attracted and collected together with the inorganic porous material by the magnetic force with the same effect as if the magnetic force acts on the oil apparently by mediating the oil adsorption force on the surface of the oil.

Further, the present invention is characterized in that a buoy having a magnetic force is floated on a water surface on which the magnetic oil is floated.

According to the present invention, the buoy having the magnetic force is floated on the surface of the water on which the magnetic oil is floated, so that the oil with the magnetic force is held around the buoy, and the oil is thinned on the sea surface. Spreading can be prevented.

Further, the present invention is characterized in that the water surface on which the magnetic oil is floated is surrounded by a magnetic fence.

According to the present invention, the water surface on which the magnetic oil is floated is surrounded by the magnetic fence, so that the oil sucked by the magnetic force is prevented from traveling over the fence and spreading widely on the water surface. be able to.

In the present invention, the magnetic force is generated by utilizing a superconducting phenomenon.

According to the present invention, since the magnetic force generated by utilizing the superconducting phenomenon is utilized, a strong magnetic field generates an attractive force not only for a ferromagnetic material but also for a paramagnetic material, thereby efficiently imparting magnetism. The recovered oil can be recovered.

Further, the present invention relates to a magnetic substance for recovering oil floating on a water surface by magnetic force, the magnetic substance being fine particles magnetizable in a state of being dispersed in oil, and the surface of the magnetic fine particles. And a hydrophobic coating covering the magnetic material.

According to the present invention, the magnetic material of the fine particles can be magnetized in a state of being dispersed in the oil, and the surface of the magnetic fine particles is covered with the hydrophobic coating, so that the magnetic material of the fine particles having a strong affinity for the oil can be obtained. Is dispersed in oil, and the magnetic material of the fine particles is magnetized to be magnetically attracted, whereby an attractive force can be applied to the oil via the magnetic material of the fine particles. Therefore, by dispersing a magnetic material of fine particles whose surface is covered with a hydrophobic film in oil floating on the water surface, the oil can be efficiently recovered by magnetic force.

In the present invention, the hydrophobic coating is a fatty acid represented by CH ₃ (CH ₂ ) _n COOH.

According to the present invention, the surface of the magnetic material of the fine particles is covered with a fatty acid film to impart hydrophobicity, enhance affinity with oil, and perform efficient magnetic separation of oil.

In the present invention, the fatty acid is stearic acid.

According to the present invention, a coating of stearic acid is formed on the surface of the magnetic material of fine particles to impart hydrophobicity to the magnetic fine particles and increase the affinity with oil to efficiently recover oil by magnetic separation. Can be performed.

In the present invention, the magnetic material of the fine particles is a magnetic iron oxide containing magnetite.

According to the present invention, since magnetic iron oxide containing magnetite is used as the magnetic material of the fine particles, it is easy to be magnetized, and the attraction action by the magnetic force can be effectively used.

Further, the present invention provides a magnetic material for recovering oil floating on a water surface by magnetic force, wherein the inorganic porous material contains expanded graphite which selectively absorbs oil on the surface, and the inorganic porous material contains And a magnetic material contained therein.

According to the present invention, since the magnetic material of fine particles is dispersed in the inorganic porous material containing expanded graphite which selectively adsorbs oil on the surface, the oil on the water surface is adsorbed by the inorganic porous material. The oil adsorbed on the inorganic porous material by the magnetic force can be efficiently collected. Expanded graphite as an inorganic porous material is mainly composed of carbon, so the recovered expanded graphite can be burned and disposed of, and it can be quickly recovered and treated in the event of an emergency fuel oil spill. It is possible.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic concept of recovering heavy oil flowing out on the sea surface as one embodiment of the present invention. FIG. 1A shows a schematic configuration for recovering the heavy oil 2 using a magnetic separation method in a state where the heavy oil 2 that has flowed out due to an accident or the like is floating on the surface of the seawater 1.
The magnetic material 3 is dispersed in the heavy oil 2. The recovery boat 4 that recovers the heavy oil 2 has a recovery device 5 that suctions the magnetic body 3 by magnetic force. The recovery device 5 is also provided with a pump, and the heavy oil 2 is sucked together with the seawater 1 from the sea surface by the water absorption pipe 6, and the remaining seawater 1 from which the heavy oil 2 has been recovered is returned to the sea by the drain pipe 7. The magnetic substance 3 can be dispersed in the heavy oil 2 by spraying the magnetic substance 3 together with a gas or a liquid.

A magnetic separation device is provided in the recovery device 5, and the magnetic material 3 is sucked from a mixed solution of seawater 1 and heavy oil 2. As shown in FIG. 1B, the magnetic substance 3 of the present embodiment is formed by covering the surface of a magnetite 10 as a magnetic substance of fine particles with stearic acid 11, which is a kind of fatty acid. The magnetite 10 is easily magnetized by single magnetic domain particles and shows hydrophilicity, but the surface of the magnetite 10 is covered with stearic acid 11, so that the magnetic body 3 as a whole shows hydrophobicity. Since the surface of the stearic acid 11 has a high affinity with the heavy oil 2 due to the hydrophobic interaction, the magnetic substance 3
When the magnetite 10 is attracted by the magnetic force of the magnetic separator in the recovery device 5, the surrounding heavy oil 2 is also attracted to the magnetic separator and the separation of the seawater 1 and the heavy oil 2 is performed. It can be performed. The magnetic substance 3 can be recovered from the separated heavy oil 2 by using a magnetic force or the like and used repeatedly.

As described above, the heavy oil in which the magnetic substance 3 is suspended can be selectively separated by magnetic force.
Secondary waste can be minimized, the system can be used repeatedly, and the processing speed can be increased. From these characteristics, it is possible to perform oil recovery with a view to environmental protection. The magnetite 10 used for imparting magnetism to the heavy oil 2 is an inverse spinel-type iron oxide, which is abundant in resources and can be used at low cost without causing any harm to the environment. Other magnetic oxides of magnetite can be used as well.

FIG. 2 shows a basic operation procedure for recovering the heavy oil 2 as shown in FIG. When a heavy oil 2 spill accident or the like occurs, the collection procedure of step a1 is started. In step a2, the magnetic substance 3 is sprayed on the heavy oil 2 that has flowed out. The heavy oil in which the magnetic substance 3 is dispersed is sucked by magnetic force, separated from the seawater 1 by using the recovery device 5 in step a3, and the recovery procedure is ended in step a4. In the present embodiment, for example, as described above, stearic acid 11
The magnetic body 3 which has been subjected to the process of forming the film of the above is used. The recovery of the heavy oil 2 using such a magnetic substance 3 is based on the knowledge obtained from the following experimental results.

FIG. 3 shows the comparison of the recovery rate of magnetite-suspended oil in distilled water with a white circle and in a 0.55 M (mol) NaCl aqueous solution (brine) corresponding to seawater in a black circle. Shown. Heavy oil C is used as the oil, and magnetite has an average particle size of 0.2 μm. Heavy fuel oil C is charged into 50 g of distilled water or saline at a ratio of 5 g, and magnetite is further added at a ratio of 0.025 g to 0.1 g, and stirred for 5 minutes using a magnetic stirrer. After the stirring, a samarium-cobalt (Sm-CO) permanent magnet is applied to the bottom of the container, the portion attracted by the magnetic force is fixed to the bottom of the container, and the supernatant is discarded. Then, after removing the water remaining in the container, the weight of the heavy oil is measured, and the recovery rate is calculated according to the following first formula. Here, the weight of the magnetite is sufficiently small relative to the weight of the heavy oil, and is ignored.

[0032]

(Equation 1)

[0033] The wall surface adhesion amount is the weight of heavy oil on the wall surface of the container. The amount of adhesion to the wall surface is determined by stirring water and heavy oil in the same procedure, then discarding the mixture from the container without using a permanent magnet, and measuring the water after removing the water.

From the results shown in FIG. 2, it can be seen that when the ratio of magnetite added to heavy oil is increased, the recovery rate is increased. Thus, the possibility of magnetically separating heavy oil and water and recovering heavy oil by this method is considered. It turned out that there is. Also, instead of distilled water, the same salt concentration as ordinary seawater, 0.55
Since the separation could be carried out in the same manner even with a molar (mol / dm ³ ) aqueous solution of sodium chloride, it was confirmed that this separation method was applicable to seawater.

Next, when magnetic separation is carried out in the ocean, it is necessary to reduce the amount of magnetite used for heavy oil in order not to place a burden on the environment and to improve economic efficiency.
As a method therefor, it is considered that the surface of magnetite, which is hydrophilic, is changed to hydrophobic, so that heavy oil easily adheres to the surface of magnetite particles, and the recovery rate is improved.

FIG. 4 shows the result of a hydrophobizing treatment for forming a stearic acid film on the surface of magnetite. Solid circles show data for the saline solution of FIG. 3, white circles show results with hydrophobic surface treatment with stearic acid. When the stearic acid treatment is performed, the recovery rate can be increased about 1.5 times on average. Since there is no difference in the magnetic properties and particle size of the magnetite itself, it can be seen that the hydrophobizing treatment is very effective in increasing the recovery rate of heavy oil.

The stearic acid 11 shown in FIG. 1B is a kind of fatty acid represented by the following second formula. An alcohol solution in which such a fatty acid is adjusted to a predetermined concentration is prepared, and a magnetic substance of fine particles is charged and mixed, and the alcohol is removed by elevating the temperature to remove the alcohol. A coating can be formed. CH ₃ (CH ₂ ) _n COOH (2)

FIG. 5 shows the experimental results on the relationship between the number of carbon (C) atoms of the fatty acid represented by the formula (2) and the recovery rate of heavy oil. In the recovery experiments, heavy fuel oil C was used as described above, and magnetite was used at a weight ratio of 1% to the oil. From the experimental results shown in FIG. 5, it can be seen that stearic acid having a total of 18 carbon atoms and n = 16 has the best recovery rate. However, it can be seen that the recovery rate of other fatty acids is particularly good if the number of carbon atoms is 10 or more.

The following Table 1 shows that the weight ratio of various oils was 1% by using a magnetic material 3 whose surface was hydrophobized with stearic acid 11 as shown in FIG.
The recovery rates when added are shown for comparison. ◎ mark is recovery rate 6
At 0% or more, ○ indicates 20 to 60%, and △ indicates 1 to 20%. From the results in Table 1, it is determined that any oil can be recovered.

[0040]

[Table 1]

As a magnetic substance applicable to the present invention, not only a fatty acid such as stearic acid but also a treatment with an aromatic carbon acid as a surface treatment for imparting hydrophobicity can impart hydrophobicity. Can be granted. Basically,
In addition to fatty acids, for example, a silane coupling agent or a titanium coupling agent represented by the following chemical formula 1 is also applicable. If the material has a linear or side chain alkyl group disposed on the surface, the hydrophobicity of the alkyl group represented by the following chemical formula 2 can enhance the affinity with oil such as heavy oil.

[0042]

Embedded image

[0043]

Embedded image

Also, as a magnetic material of fine particles, FIG.
In addition to the magnetite shown in (b), other magnetic oxides can be used as described above. In particular, considering use in a strong magnetic field of 1 T or more generated using a superconducting coil or the like, a paramagnetic iron oxide such as hematite or goethite can be used. in this way,
If a magnetic force is generated using the superconductivity phenomenon, the efficiency and speed of oil recovery can be increased.

FIG. 6 shows another embodiment of the present invention.
The buoy 20 is dropped in a state where the magnetic substance 3 is dispersed in the heavy oil 2 floating on the surface of the seawater 1, and the magnet 21 in the buoy 20 is dropped.
The basic concept of preventing heavy oil 2 from spreading thinly by suction is shown below. FIG. 6A shows a single unit, and FIG.
Shows a state in which ten or more buoys 20 are thrown in and continuously operated by the built-in magnet 21 to serve as an oil fence. Such a buoy 20 can be efficiently used, for example, when a spill accident of the heavy oil 2 occurs, the magnetic substance is sprayed on an aircraft immediately, and the buoy 20 is dropped on the spill site to prevent the spread of the heavy oil 2.

FIG. 7 shows a basic concept of a fence 25 for preventing the spread of heavy oil 2 floating on seawater 1 as still another embodiment of the present invention. A magnet 26 is included in the fence 25, and the magnetic substance 3 dispersed in the heavy oil 2 is attracted by magnetic force, so that the heavy oil 2 passes over the fence 25 and receives the seawater 1.
Can be prevented from spreading widely on the surface of the object.

In each of the embodiments of the present invention described above, the heavy oil 2 floating on the surface of the seawater 1 is collected and prevented from spreading. However, other oils shown in Table 1 and also crude oil and industrial waste are used. The present invention can also be applied to the recovery of waste oil and the like discarded as waste and the prevention of contamination. As shown in FIG. 3 and FIG. 4, the present invention can be similarly applied to seawater or fresh water, and oil can be easily separated from the water surface.

The oil such as the heavy oil 2 recovered by the recovery device 5 as shown in FIG. 1 contains the magnetic material 3, so that the magnetic material 3 is further separated by the magnetic force and the magnetic material 3 is used repeatedly. It is also possible. Also, if magnetite 10 or the like is used as the magnetic material 3, since it has abundant resources and has no influence on the environment, it can be burned together with, for example, heavy oil 2. For example, the recovery vessel 4 urgently recovers the heavy oil 2 from the spill accident and burns the separated heavy oil 2 for disposal, or mixes the recovered heavy oil 2 with the magnetic material 3 into fuel for incineration of refuse. Can be incinerated.

[0049]

As described above, according to the present invention, a magnetic material of fine particles having a surface subjected to a hydrophobic treatment is dispersed to impart magnetism to oil, and is efficiently separated from water by being attracted by magnetic force. be able to.

Further, according to the present invention, the magnetic material of fine particles is dispersed in expanded graphite which can selectively adsorb the oil to the surface, so that the oil can be efficiently separated from the water together with the expanded graphite.

Further, according to the present invention, it is possible to prevent the oil from being magnetically adsorbed around the buoy and spreading thinly on the water surface.

Further, according to the present invention, the oil can be surrounded by the fence, and the oil can be prevented from spreading over the water surface through the fence by the magnetic force.

Further, according to the present invention, oil can be efficiently recovered by a strong magnetic force generated by utilizing the superconducting phenomenon.

Further, according to the present invention, the magnetic material of fine particles is dispersed in oil, and the oil is strongly bonded to the magnetic material of fine particles by the affinity of the hydrophobic coating covering the surface of the magnetic material of fine particles. Oil can be efficiently recovered by the magnetic force acting on the magnetic material.

Further, according to the present invention, since the fatty acid is used to form a film for increasing the affinity of the fine magnetic particles with the oil, the hydrophilic magnetic fine particles can be easily imparted with hydrophobicity. it can.

Further, according to the present invention, since stearic acid is used as a fatty acid, a small amount of fine particles of a magnetic substance can be efficiently dispersed in oil to impart magnetism to oil.

Further, according to the present invention, since a magnetic oxide containing magnetite is used as the magnetic material of the fine particles, it can be easily magnetized in oil, and the oil can be efficiently recovered using magnetic force. it can. Even in the case where the recovered oil is burned, it can be disposed of with little influence on the environment.

Further, according to the present invention, since the magnetic material is dispersed in the inorganic porous material containing expanded graphite which selectively adsorbs the oil on the surface, the magnetic force is also used to recover the oil by the inorganic porous material. Thus, the collection can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a simplified cross-sectional view showing a basic concept of an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of the concept of FIG. 1;

FIG. 3 is a graph showing the relationship between the recovery rate of heavy oil and the addition rate of magnetite with respect to distilled water and saline.

FIG. 4 is a graph showing the relationship between the presence or absence of surface treatment for imparting hydrophobicity to magnetite, the recovery rate of heavy oil, and the amount of magnetite added.

FIG. 5 is a graph showing the relationship between the carbon number of fatty acids and the oil recovery.

FIG. 6 is a simplified plan view showing a concept of retaining heavy oil in another embodiment of the present invention.

FIG. 7 is a simplified cross-sectional view showing a concept of retaining heavy oil in still another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 seawater 2 heavy oil 3 magnetic material 4 recovery boat 5 recovery device 10 magnetite 11 stearic acid 20 buoy 21, 26 magnet 25 fence

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[Submission date] December 24, 1999 (1999.12.
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 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Keisuke Fukunaga 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kawasaki Heavy Industries, Ltd., Tokyo Head Office (72) Inventor Yasutaka Kuramochi, Hamamatsucho, Minato-ku, Tokyo 2-4-1, World Trade Center Building, Tokyo Head Office, Kawasaki Heavy Industries, Ltd. (72) Inventor Akira Iwata 118, Futatsuka, Noda-shi, Chiba Kawasaki Heavy Industries, Ltd. Noda Plant (72) Inventor Shigehiro Nishijima, Hatano, Kameoka-shi, Kyoto 3-50 Gongen Machihirono (72) Inventor Shinichi Takeda 1-4-1 Tsushima Nishizaka, Okayama City, Okayama Prefecture (72) Inventor Atsushi Nakahira 2-5-54, Goryominegadoucho, Nishikyo-ku, Kyoto, Kyoto F-term (reference) 2D025 BA31 4D051 AA01 AB07 CA26 DD22 EA02 EA08 EA11 EB02 EC02 EC09 EC11 4D061 DA09 DB20 DC01 EA18 EC02 EC05 EC11 ED20 FA06 FA20

Claims (10)

[Claims] 1. A method of recovering oil floating on a water surface, comprising: dispersing fine particles of a magnetic material whose surface has been subjected to a hydrophobic treatment into the oil on the water surface; And recovering the oil by attracting the magnetic material with a magnetic force. 2. A method for recovering oil floating on a water surface, comprising: an inorganic porous body containing expanded graphite containing a magnetic substance therein;
Sprinkle on oil on the water surface to absorb the oil, and magnetically attract the inorganic porous material that has absorbed the oil,
An oil recovery method by magnetic separation, comprising recovering oil. 3. The oil recovery method by magnetic separation according to claim 1, wherein a buoy having a magnetic force is floated on a surface of the water on which the magnetized oil floats. 4. The method for recovering oil by magnetic separation according to claim 1, wherein a water surface on which the magnetic oil is floated is surrounded by a fence having magnetic force. 5. The oil recovery method according to claim 1, wherein the magnetic force is generated using a superconducting phenomenon. 6. A magnetic material for recovering oil floating on a water surface by magnetic force, wherein the magnetic material is a fine particle magnetizable in a state of being dispersed in the oil, and covers a surface of the magnetic material of the fine particle. A magnetic material for oil recovery, comprising: a hydrophobic coating. 7. The magnetic material for oil recovery according to claim 6, wherein the hydrophobic coating is a fatty acid represented by CH ₃ (CH ₂ ) _n COOH. 8. The magnetic material for oil recovery according to claim 7, wherein the fatty acid is stearic acid. 9. The magnetic material for oil recovery according to claim 6, wherein the magnetic material of the fine particles is a magnetic iron oxide containing magnetite. 10. An inorganic porous body containing magnetic graphite for recovering oil floating on a water surface by magnetic force, the expanded porous graphite including a surface for selectively adsorbing oil, and an inorganic porous body contained in the inorganic porous body. And a magnetic material for oil recovery.