JPH026593A - Production of binder pitch with low ash content - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing low ash binder pitch.

Conventional technology H contained in graphite electrodes for electric furnaces and carbon electrodes for aluminum refining
It is said that trace components such as a, Si, Zn, Pb, and Fe have an adverse effect on the usage characteristics of the electrode. For example, Ha is said to have a catalytic action that promotes oxidative consumption under the usage conditions of the electrode. Since Si forms hard SiC during the electrode manufacturing process, it is said that it has the effect of accelerating the wear of the blade in the final electrode processing process. Further, the trace components are eluted from the electrode during the process of using the electrode and mixed into the product, so when manufacturing products that require high purity, electrodes with a high content of the trace components cannot be used.

These trace components in the electrode are contained as ash in pitch, which is one of the raw materials for manufacturing the electrode. For the above reasons, the lower the ash content in the pitch, the better, and the best is zero ash content.

The ash content in pitch is the concentrated ash content in coal tar, which is a raw material for producing binder pitch.

Coal tar is produced as a by-product when coal is carbonized in a coke oven, and the coal tar generated in a coke oven is usually separated by sedimentation and centrifugation to remove large-sized sludge such as coke powder. . However, fine particles cannot be removed by the above operation, and these fine particles, which mainly contain the above-mentioned trace components, remain in the coal tar as ash.Normally, the coal tar after desludging contains no ash. Contains .01-0.2%. The soft pitch obtained by distilling this coal tar usually contains 0.01 to 0.25% ash. Binder pitch is usually obtained by thermally polymerizing soft pitch obtained by distilling coal tar.

The ash content in coal tar varies greatly depending on the type of coal used. The blending ratio of coal in a coke oven changes depending on various factors such as the coal supply situation.

For this reason, conventionally, when producing a low ash binder pitch, coal tar with a low ash content has been selected and used as a raw material.

In addition, as seen in JP-A-54-103213, soft pitch is obtained by removing the quinolinated content (hereinafter abbreviated as QI) from soft pitch using a centrifugal separation method, a solvent extraction method, etc. Binder pitch obtained by distilling to remove low-boiling components does not contain any ash.

Problems to be Solved by the Invention However, in the above method of selectively using the raw material coal tar, due to the constraint of ash content, not all of the generated coal tar can be used as a raw material for producing low ash binder pitch. However, there were problems in securing stable raw materials. For this reason, it has been desired to develop a method for producing low-ash binder pitch that does not depend on the properties of raw coal tar.

Furthermore, since the method proposed in Japanese Patent Application Laid-Open No. 54-1032f1 removes all QI in the tar, the above-mentioned electrode using this binder pitch has problems in terms of mechanical properties.

The present invention provides a method for producing a low-ash binder pitch that satisfies the required ash properties without depending on the properties of the raw material coal tar, while providing the pitch with the QI necessary to ensure the mechanical strength of the electrode. This is what we provide.

Means to solve problems The configuration of the present invention is as follows.

(1) A method for producing a low-ash binder pitch, which comprises adding and mixing an ash-free binder pitch to pitch obtained by thermally polymerizing soft pitch containing 0.01 to 0.25% ash.

(2) A method for producing a low-ash binder pitch, which comprises adding and mixing an ash-free binder pitch to a soft pitch containing 0.01 to 0.25% ash, followed by thermal polymerization.

(3) Production of a low-ash binder pitch characterized by adding and mixing a binder pitch obtained by thermally polymerizing an ash-free binder pitch to a pitch obtained by thermally polymerizing a soft pitch containing 0.01 to 0.25% ash. Method.

(4) A method for producing a low-ash binder pitch, which comprises adding and mixing ash-free soft pitch to soft pitch containing 0.01 to 0.25% ash and then thermally polymerizing the mixture.

The present invention will be explained in detail below.

FIG. 5 shows a known soft pitch manufacturing process, in which coal tar 14 generated from a coke oven 9 is desludged in a sedimentation separator 10 and a centrifugal separator 11, and then water is removed in a dehydration distillation column 12. Ash content removed: 0.01~
0.2%, TI2~15%, QII~10%, moisture O%
A soft pitch having a softening point of 20 to 40°C is obtained by removing low-boiling components from the coal tar in a coal tar distillation column 13.

Figure 6.7 shows the production process of a known ash-less, QI-less binder pitch. Figure 6 shows the addition and mixing of aromatic solvent 7 and aliphatic solvent 8 to soft pitch 1. The precipitated component 15 is separated in the deashing unit IB to obtain ash-free, QI-free soft pitch 6. This soft pitch is fed to the pitch distillation column 4 to remove low molecular weight components, thereby producing ash-free, QI-free pitch. This is to obtain a binder pitch of 2 with less.

The ash content in the soft pitch 1 is determined in the deashing device 16 at a ratio of 0.2 to 0.5 parts of the aromatic solvent 7 to 1 part of the soft pitch 1, and 0.5 to 0.5 parts of the aliphatic solvent 8. It can be added and mixed at a ratio of 0.8 part, and the precipitated insoluble substances can be separated and removed, and as a result, soft pitch 6 with no ash content and no QI can be obtained.

Figure 7 shows that soft pitch 6 with no ash and no QI is obtained by adding and mixing aromatic solvent 7 to soft pitch 1 and separating ash and QI with a filtration device or centrifugal separator M11. is supplied to the pitch distillation column 4 and low molecular weight components are removed to obtain ash-free and QI-free binder pitch 2.

The present invention basically deals with soft pitch containing ash and QI obtained by the process shown in FIG. 5 and ash-free, QI-free soft pitch or ash-free pitch obtained by the process shown in FIG. By mixing with a QI-free binder pitch, a binder pitch containing QI can be obtained with a required ash content.

Figures 1 to 4 show the manufacturing process of the low ash binder pitch of the present invention.

Figure 1 shows soft pitch 1 containing ash and QI that has been thermally polymerized in a pitch reformer 3, and ash-free and QI-free binder pitch 2 added thereto, then fed to a pitch distillation column 4 and softened. By adjusting the point, a binder pitch 5 having the required ash content and QI can be obtained.

The ash content of binder pitch 5 is soft pitch l and ash content-less, Q
This is adjusted by adjusting the mixing ratio of I-less binder pitch 2. Other characteristic values of binder pitch 5 include temperature, pressure, residence time, etc. of pitch reformer 3 and pitch distillation column 4! ! Adjustments are made by doing this.

Figure 2 shows soft pitch 1 including ash and QI, and soft pitch 1 with no ash and QI.
A mixture of non-binder pitch 2 is thermally polymerized in a pitch reformer 3 and then supplied to a pitch distillation column 4.
By adjusting the softening point to OIm, a binder pitch 5 having a required ash content and containing QI can be obtained.

The ash content of binder pitch 5 is the same as soft pitch 1 and has no ash content, Q
This is adjusted by adjusting the mixing ratio of I-less binder pitch 2. Other characteristic values of the binder pitch 5 are adjusted by adjusting the temperature, pressure, residence time, etc. of the pitch reformer 3 and the pitch distillation column 4.

Figure 3 shows that soft pitch 1 containing ash and QI is thermally polymerized in the pitch modification device 3, and ash-free and QI-free binder pitch 2 is thermally polymerized in the pitch modification device 3.
After mixing, the mixture is supplied to a pitch distillation column 4 and the softening point is adjusted to obtain a binder pitch 5 having a required ash content and containing QI.

The ash content of binder pitch 5 is the same as soft pitch 1 and has no ash content, Q
This is adjusted by adjusting the mixing ratio of I-less binder pitch 2. Other characteristic values of the binder pitch 5 are adjusted by adjusting the temperature, pressure, residence time, etc. of the pitch reformer 3 and the pitch distillation column 4.

Figure 4 shows soft pitch l including ash content and QI, ash content less, and QI.
A mixture of low-res soft pitch 6 is thermally polymerized in a pitch reformer 3 and then supplied to a pitch distillation column 4 to obtain a binder pitch 5 containing K-QI with a required ash content. It is.

The ash content of binder pitch 5 is the same as soft pitch 1 and has no ash content, Q
This is adjusted by adjusting the mixing ratio of the I-less soft pitch 6. Other characteristic values of the binder pitch 5 are adjusted by adjusting the temperature, pressure, residence time, etc. of the pitch reformer 3 and the pitch distillation column 4.

Example (1) The soft pitch IL with an ash content of 0.08% obtained by the process shown in Fig. 5 was thermally polymerized, and the soft pitch IL obtained by the process shown in Fig. 6 was added.
After adding and mixing 0.9 t of binder pitch with an ash content of 0.01% or less, the softening point was adjusted to 105° C. by distillation to obtain binder pitch. The quality of the binder pitch is toluene insoluble content (hereinafter abbreviated as TI) 25.5
%, QI5.8%, fixed carbon (hereinafter abbreviated as FC) 58
．． 0%, and ash content was 0.04%.

(2) Soft pitch IT with an ash content of 0.08% obtained by the process shown in FIG. 5 was obtained by the process shown in FIG. 6. After adding and mixing 0.9 t of binder pitch with an ash content of 0.01% or less and thermally polymerizing, the softening point was adjusted to 105° C. by distillation to obtain binder pitch. The quality of the binder pitch is T I 29.2%, QI 9.0%, FC 58.5%,
The ash content was 0.05%.

(3) 1 ton of soft pitch with an ash content of 0.08% obtained through the process shown in FIG. After addition and mixing, the softening point was adjusted to 105° C. by distillation to obtain binder pitch. The quality of the binder pitch is T I 29.8%, QI 9.2
%, FC513.0%, and ash content 0.05%.

(4) 2.7 tons of soft pitch with an ash content of 0.01% or less obtained by the process in Figure 6 was added to 1 ton of soft pitch with an ash content of 0.08% obtained in the process in Figure 5 and mixed with Φ, and thermally polymerized. Thereafter, the softening point was adjusted to 105° C. to obtain a binder pitch. The quality of the binder pitch is T I 25.0%, QI 6.
0%, FC57.8%, and ash content 0.06%.

The properties of the soft pitch, including the ash content and QI listed in (1) to (4) above, are: softening point 30.0°C, T I 15.5%,
The QI was 5.6%.

In addition, the properties of the binder pitch with an ash content of 0.01% or less in (1) to (4) are a softening point of 88.5°C, a TI of 9.3%,
QI was 0%. The heat treatment conditions for thermal polymerization in (1) to (4) were a temperature of 380°C and a residence time of 12 hours.

Effects of the Invention The features of the present invention are soft pitch including ash content and QI;
By mixing with soft pitch of less or binder pitch, P2000 can have the QI required to ensure the mechanical strength of the electrode, and the ash in the pitch can be reduced without depending on the properties of the raw material coal tar. It is possible to reduce the amount to a target value.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams of the manufacturing process of the low ash binder pitch of the present invention. FIG. 5 is an explanatory diagram of a conventional soft pitch manufacturing process. FIGS. 6 and 7 are explanatory diagrams of the conventional manufacturing process of ash-free and QI-free binder pitch. 1...Soft pitch, 2...Ash content-less, QI-less binder pitch, 3...Pitch reformer, 4-fisted fist pitch distillation column, 5...Binder with required ash content and containing QL Pitch, 6 - Ash content free, QI free soft pitch,
7. Aromatic solvents, 8. - Aliphatic solvents, 9@.
- Coke oven, 10... Sedimentation separation device, 11... Filtration device or centrifugal separator, 12... Dehydration distillation column,
13... Coal tar distillation column! 4+1・Fist coal tar, 15...Sedimentation component, 1B...Deashing device.

Claims (1)

[Claims] (1) Production of a low-ash binder pitch characterized by adding and mixing an ash-free binder pitch to pitch obtained by thermally polymerizing soft pitch containing 0.01 to 0.25% ash. Method. (2) A method for producing a low-ash binder pitch, which comprises adding and mixing an ash-free binder pitch to a soft pitch containing 0.01 to 0.25% ash, followed by thermal polymerization. (3) Production of a low-ash binder pitch characterized by adding and mixing a binder pitch obtained by thermally polymerizing an ash-free binder pitch to a pitch obtained by thermally polymerizing a soft pitch containing 0.01 to 0.25% ash. Method. (4) A method for producing a low-ash binder pitch, which comprises adding and mixing ash-free soft pitch to soft pitch containing 0.01 to 0.25% ash and then thermally polymerizing the mixture.