JPH0469349A - Method for separating and recovering crude anthracene - Google Patents

Abstract

PURPOSE:To obtain the subject high-purity substance at a low cost by feeding cooled anthracene oil to a centrifugal separator, sticking the crystals of the crude anthracene to the peripheral sidewall of a basket, jetting a solvent to the aforementioned crystals, draining the liquid and then scraping off the crystals. CONSTITUTION:Anthracene oil in an amount of one batch is jetted from a jetting port 9 of a feed pipe 7 to the peripheral side face of a basket 3 during rotation at a prescribed rotational speed to form a crystal layer and a prescribed solvent (e.g. benzene, cyclohexane, acetone, tar base or light oil) (at 40-60 deg.C) is then jetted from jetting ports 10 of a feed pipe 8 to the crystal layer. The basket is subsequently rotated for a prescribed time to drain the liquid from the crystal layer. A scraping plate 11 is then advanced to the peripheral side face of the basket to scrape off the crystal layer and the resultant crystals are deposited through an opening 5 downward. The body of the centrifugal separator is provided with a heat insulating jacket 2 for keeping both the washing ability and the temperature in the basket constant.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for separating and recovering crude anthracene, and particularly provides a method for separating and recovering crude anthracene that can separate and recover highly purified crude anthracene at low cost. It is something.

(Prior Art) The 300-380°C fraction in tar distillation contains anthracene, carbazole, phenanthrene components, etc. and is called anthracene, tt+. The anthracene oil obtained by cooling the anthracene oil to precipitate crystalline components and separating and recovering them is called crude anthracene. Crude anthracene is used as a raw material for dyes and a digesting agent for pulp, while decrystallized anthracene oil is used as a raw material for creosote oil. A method for separating and collecting crystalline components is to use a centrifuge.

There are methods such as using a filter press, but the method using a centrifuge is shown below.

In the process of cooling anthracene oil and separating and recovering crude anthracene using a centrifuge, crude anthracene crystals with anthracene purity of about 30% are usually obtained, but depending on the nature of the raw material tar and the tar distillation conditions,
Purities as low as less than 25% may be obtained. Raw materials for the production of high-purity anthracene are required to have a purity of 25% or more, but conventionally, raw materials with a purity of less than 25% are pre-purified to increase the purity and produce high-purity andhracene of 90% or more. It is used as a raw material.

As a pre-purification method, there are two methods: (1) Adding a solvent such as tar light oil to dissolve the crystals, recrystallizing them and separating them by filtration, or (2) Using a press to remove the oil in the crude anthracene, There are ways to improve the purity of

(Problem to be solved by the invention) Although the method of recrystallizing by adding a solvent greatly improves the purity, it requires many steps such as dissolution, recrystallization pit filtration, and separation, and the processing time is longer than several tens of hours. The amount of solvent used is 4
The cost is high because it is ~6 times as large. Furthermore, since the method using a press only removes oil, the improvement in purity depends on the oil content in the crystals, but is only a few percent, which is small.

The present invention provides a method for separating and recovering crude anthracene, which can significantly improve purity at low cost.

(Means for Solving the Problems) The gist of the present invention is as follows. Anthracene oil cooled to a temperature at which the anthracene component crystallizes is supplied to a centrifuge, and crude anthracene crystals are attached to the peripheral wall of the basket of the centrifuge, and the attached crude anthracene crystals are scraped and collected. This separation and recovery method for crude anthracene is characterized in that, before scraping, a solvent is injected toward the crude anthracene crystals attached to the peripheral wall of the rotating basket.

(Function) In Fig. 1, 1 is a casing of a centrifuge, 2 is a heat insulating jacket provided on the outer periphery of the casing, 3 is a rotatably provided basket inside the casing, and 4 is a filter attached to the inner surface of the basket. The cloth 5 is a chute provided at the lower end of the casing 1 for discharging crystals. A gutter 6 is provided between the casing 1 and the basket 3 to receive the decrystallized anthracene oil, and is discharged to the outside of the centrifugal separator through an exhaust pressure pipe (not shown). 7 and 8 are anthracene oil supply pipes and solvent supply pipes, and 9 and 10 are injection ports thereof. The injection directions of the injection ports 9 and 10 are different in the circumferential direction. Reference numeral 11 denotes a scraping plate which is movable up and down within the basket and is movable toward the peripheral surface of the basket.

The steps for recovering crude anthracene using a centrifuge are as follows. (2) Anthracene oil corresponding to one batch is injected from the injection port 9 of the supply pipe 7 onto the circumferential side of the rotating basket at a constant rotational speed to form a crystal layer on the circumferential side of the basket. ■After spraying a predetermined amount, rotate the basket for a predetermined period of time to remove liquid from the crystal layer. ■ The scraping plate 11 is advanced toward the peripheral side of the basket, enters into the crystal layer, and then lowered to scrape off the crystals, discharge them to the discharge chute through the opening 5 at the lower end of the basket, and deposit them below the lower end of the chute. .

In the above process, after forming a crystal layer, a predetermined amount of a predetermined solvent is injected from the injection port 9 toward the crystal layer via the supply pipe 8. As a result, solvent-soluble components in the crude anthracene crystals are selectively removed, increasing the anthracene content. Incidentally, the above steps can also be made continuous in batches using a sequencer.

Examples of the solvent to be sprayed are those that selectively dissolve substances other than anthracene in the crude anthracene, and known benzene, toluene, cyclohexane, acetone, tar base, light oil, etc. can be used.

The temperature of the solvent to be sprayed in the method of the present invention is preferably 40"C or higher in order to improve purity, and 60"C or lower is preferred to prevent dissolution of anthracene.

The solvent passes through the crude anthracene crystals while dissolving the solvent-soluble components in the crude anthracene crystals by centrifugal force, passes through the filter cloth, and is discharged to the outside of the centrifuge. Therefore, dissolution, filtration, and deliquification can be performed in the same process.

The solvent is sprayed so as to be uniformly supplied to the crystal surfaces. In addition, in order to keep the cleaning ability constant, in the example of the present invention, a heat insulation jacket is provided on the main body of the centrifugal separator to keep the atmospheric temperature inside the basket constant.

(Example) Table 1 shows the case of solvent injection using tar light oil at a solvent temperature of 6°C. Rotate the centrifuge to 750r
pm (500G), and the solvent injection time was 10
20 minutes, and the dewatering time was 10 minutes. Table 2 also shows the specifications of the centrifugal separator used in this example. Table 3 shows the composition of the tar light oil used in this example.

Table 4 shows the case of solvent injection using Hensen at a solvent temperature of 50°C.

These solvent injections have the advantage that they can improve purity in a short processing time of 10 to 20 minutes during the process of separating and recovering cooled anthracene oil using a centrifuge, and that the amount of solvent used can be reduced to the same level as the amount of crystals of crude anthracene. There is.

Table 1 Table 2 When using Tal diesel By injecting a solvent into crude anthracene crystals in the basket of a centrifuge, it is possible to improve the purity of anthracene at low cost, shorten processing time, and significantly improve purity.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the method of the present invention using a centrifuge. 1-Casing 2・Heat insulation jacket 3・Basket 4・・Filter cloth 5・Chute 6・Decrystallized anthracene oil receiving gutter 7・Anthracene oil supply pipe 8・・Solvent supply pipe 9・Anthracene oil injection port 10・・Solvent injection port 11...Scraper

Claims (1)

[Claims] Anthracene oil cooled to a temperature at which the anthracene component crystallizes is supplied to a centrifuge, and crude anthracene crystals are attached to the peripheral wall of the basket of the centrifuge, and the attached crude anthracene crystals are scraped off and recovered.Separation and recovery of crude anthracene A method for separating and recovering crude anthracene, which comprises injecting a solvent toward crude anthracene crystals adhering to the peripheral wall of a rotating basket before scraping.