JP2003181494A - Separation method of iron particles and fats and oils in sludge - Google Patents

Abstract

(57) [Summary] [Problem] To provide a method for separating iron particles and oils and fats efficiently and reusably when separating iron particles and oils and fats from sludge containing iron particles and oils and fats. SOLUTION: An alkali solution is added to a sludge containing iron particles, oil and fat, and ultrasonic stirring is performed. At the same time, a magnetic force is applied to the iron particles using a magnet to cause the magnet to adsorb the iron particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating iron particles and fats and oils from sludge generated in a hot rolling process or a cold rolling process of a steel sheet.

[0002]

2. Description of the Related Art A rolling roll used when hot-rolling or cold-rolling a steel sheet (hereinafter referred to as "rolling") causes surface defects or wear due to friction with a steel sheet used for rolling. To do. Therefore, the surface of the rolling roll is ground regularly, and when it is difficult to repair the surface by grinding the rolling roll, the rolling roll is exchanged for operation. Such grinding or replacement of the rolling rolls increases the cost required for maintenance and management of the rolls and increases the manufacturing cost of the steel sheet.

Therefore, rolling lubricating oil is used for the purpose of reducing the friction coefficient between the rolling roll and the steel sheet. When the rolling lubricant is supplied between the rolling roll and the steel sheet, not only the friction coefficient between the rolling roll and the steel sheet decreases but also the rolling load decreases, so that the driving force of the rolling roll can be reduced. As a result, in addition to reducing maintenance costs for rolls, it also has the effect of reducing power consumption.

Generally, the rolling lubricant is mixed with water (also referred to as dilution water) and then supplied between the rolling roll and the steel sheet through a spray nozzle. By rolling, iron particles are peeled off from the steel plate or rolling roll and mixed in the mixed liquid of rolling lubricating oil and dilution water. In this way, the mixed liquid of the rolling lubricating oil and the diluting water is collected in the storage tank in a state in which iron particles are mixed (so-called sludge).

Rolling lubricating oils are various oils and fats such as mineral oil, palm oil, beef tallow, and synthetic esters to which a rust preventive agent and an emulsifier are added. Therefore, when the iron particles and fats and oils contained in the sludge recovered from the rolling process are separated, the iron particles can be reused as a raw material for iron making, and the fats and oils can be reused as fatty acids. Therefore, various techniques have been studied to separate iron particles and fats and oils.

[0006] For example, a technique of dissolving iron particles in sulfuric acid by adding sulfuric acid to a sludge containing iron particles and oils to separate and recover the oils has been known.
However, this technique has a problem that it is difficult to reuse the iron particles in addition to the fact that waste acid treatment equipment is required because sulfuric acid is used. Further, JP-A-64-15156 discloses a method and apparatus for recovering metal particles from sludge in rolling lubricating oil. In this technique, a sludge containing metal particles and fats and oils is dipped in an organic solvent and stirred, and a magnet is used to settle the metal particles downward. However, the technique disclosed in JP-A-64-15156 can separate and collect metal particles, but has a problem that it is difficult to reuse oil and fat because an organic solvent is used.

Further, JP-A-53-2383 discloses a method for treating oil-containing sludge. This technique is intended to separate iron particles and fats and oils by centrifuging a sludge containing iron particles and fats and oils. However, the technique disclosed in Japanese Patent Laid-Open No. 53-2383 has a problem that relatively coarse iron particles can be easily separated and recovered, but it is difficult to separate fine iron particles.

[0008]

The present invention solves the above problems and efficiently separates iron particles and oils and fats from the sludge containing the iron particles, oils and fats and dilution water. Moreover, it is an object of the present invention to provide a method of separating in a reusable state.

[0009]

According to the present invention, an alkali solution is added to a sludge containing iron particles, fats and oils and ultrasonic stirring is performed, and a magnetic force is applied to the iron particles using a magnet, This is a method of separating iron particles and fats and oils by adsorbing iron particles to a magnet. In the above-described invention, as a first preferred embodiment, it is preferable to centrifuge the sludge and add an alkaline solution to the sludge after removing the separated iron particles and perform ultrasonic agitation.

In a second preferred embodiment, the alkaline solution is preferably an aqueous NaOH solution.

[0011]

FIG. 1 is a sectional view schematically showing an example of an apparatus to which the present invention is applied. A sludge 1 containing iron particles, fats and oils and water is placed in a container 4 and an alkaline solution is added. Further, the ultrasonic vibrator 2 is immersed in the sludge 1. The ultrasonic vibrator 2 vibrates by ultrasonic vibration generated from an ultrasonic oscillator (not shown) to stir the sludge 1 (so-called ultrasonic stirring).

Since the alkaline solution is added to the sludge 1, soap reacts with the oil and fat in the sludge 1 to emulsify and easily separate from the iron particles by ultrasonic agitation. On the other hand, a magnet 3 is arranged below the container 4, and a magnetic force acts on the iron particles to adsorb them. In this way, the iron particles in the sludge 1 are attracted to the magnet 3. Therefore, it is possible to easily separate the iron particles from the sludge 1,
By using sludge 1 (solution containing soap) from which iron particles have been separated, it is possible to recover fats and oils in a reusable state such as fatty acids by a conventionally known method such as reaction with sulfuric acid. Further, iron particles adsorbed on the magnet 3 can also be collected and reused.

In the present invention, prior to the addition of the alkaline solution, the sludge 1 is centrifuged in advance to separate and remove relatively coarse iron particles, that is, the sludge 1 which is a fine particle which cannot be separated by centrifugation. It is preferable to add an alkaline solution to the sludge 1 containing various iron particles, fats and oils and perform ultrasonic stirring as shown in FIG. 1 because the recovery efficiency of the iron particles is improved. Further, it is preferable to use an aqueous NaOH solution as the alkaline solution, since the fats and oils become soaps and are easily separated from the dilution water, and are inexpensive and easily available.

In the present invention, the magnet 3 may be either an electromagnet or a permanent magnet. If an electromagnet is used, the strength of the magnetic force applied to the iron particles can be easily adjusted, and further, by cutting off the electric current, the adsorbed iron particles can be easily recovered from the magnet 3. On the other hand, when a permanent magnet is used, iron particles can be adsorbed by a simple device, and therefore the cost of manufacturing and maintaining the device can be reduced. It may be appropriately selected in consideration of the characteristics of the electromagnet and the permanent magnet.

As described above, since sulfuric acid is not used in the present invention, large-scale equipment such as waste acid treatment is not required.
Moreover, both the iron particles and the oil and fat recovered from Sludge 1 can be reused.

[0016]

[Examples] In a cold rolling facility, a mixed solution obtained by emulsifying palm oil as a rolling lubricating oil with dilution water was sprayed onto a rolling roll to perform cold rolling. Iron particles were mixed in the mixed liquid of palm oil and dilution water recovered in the storage tank, and it was in a so-called sludge state.

The sludge 1 was placed in a container 4 and
A 0.05% by weight aqueous NaOH solution was added. The amount of the NaOH aqueous solution added was twice the mass of the sludge 1 in the container 4. Further, as shown in FIG. 1, the ultrasonic vibrator 2 was immersed in the sludge 1, and the sludge 1 was ultrasonically stirred. In this way, the fats and oils contained in Sludge 1 were emulsified and separated and recovered from the dilution water as soap. On the other hand, after using an electromagnet as the magnet 3 to adsorb the iron particles contained in the sludge 1, the electric current of the electromagnet was cut off to recover the iron particles. This is Example 1 of the invention.

Further, the sludge 1 is centrifuged (5000 rpm, 4
After removing the relatively coarse iron particles by separation for 1 minute), a NaOH aqueous solution was added to Sludge 1 containing fine iron particles, fats and oils and dilution water as in Invention Example 1 and ultrasonically stirred.
Since some of the oils and fats were separated by centrifugation, the separated oils and fats were collected. The other conditions are the same as those of the first example of the invention, so the description thereof is omitted. In this way, oil and fat and iron particles were recovered from Sludge 1. This is Invention Example 2.

As a comparative example, sludge 1 was centrifuged (5000 rpm, 4 minutes) to separate relatively coarse iron particles. At this time, some of the oils and fats were separated. In this way, iron particles and fats and oils were recovered from Sludge 1. The amounts of fats and oils and iron particles recovered from Sludge 1 were investigated for Invention Examples 1 and 2 and Comparative Example. The results are shown in Table 1. The recovery amounts of fats and oils and iron particles shown in Table 1 are values obtained by indexing the recovery amounts of iron particles and fats and oils with the mass of sludge 1 housed in the container 4 being 100. The recovery amount of iron particles and fats and oils of Inventive Example 2 is the total value separated by centrifugation, addition of NaOH aqueous solution, and ultrasonic agitation.

[0020]

[Table 1]

As is clear from Table 1, when the invention examples 1 and 2 were compared with the comparative example, the recovered amounts of iron particles and fats and oils were larger in the invention examples 1 and 2. Further, when comparing Inventive Example 1 and Inventive Example 2, the recovered amounts of fats and oils were equivalent, but the recovered amount of iron particles was larger in Inventive Example 2. In this way, it was confirmed that iron particles and fats and oils can be efficiently separated in the present invention.

[0022]

INDUSTRIAL APPLICABILITY According to the present invention, iron particles and oils and fats can be efficiently and reusably separated from a sludge containing iron particles, oils and fats and dilution water.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of an apparatus to which the present invention is applied.

[Explanation of symbols]

1 sludge 2 Ultrasonic transducer 3 magnets 4 containers

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Kawashima             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Chiba Steel Works, Ltd. (72) Inventor Katsuhiko Kato             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Chiba Steel Works, Ltd. F term (reference) 4D059 AA10 AA11 BE37 BK22 BK25                       DA01                 4D071 AA52 AB23 DA15

Claims (3)

[Claims] 1. An alkali solution is added to a sludge containing iron particles, fats and oils and ultrasonic agitation is performed, and a magnetic force is applied to the iron particles by using a magnet so that the iron particles are attached to the magnet. A method for separating iron particles and fats and oils, characterized by adsorbing. 2. The ultrasonic stirring is carried out by adding the alkaline solution to the sludge after removing the separated iron particles by centrifuging the sludge.
The method for separating iron particles and fats and oils according to. 3. The method for separating iron particles and fats and oils according to claim 1, wherein the alkaline solution is a NaOH aqueous solution.