JPS61130391A - Production of tar pitch - Google Patents

Abstract

PURPOSE:To obtain tar pitch which has a high solid carbon content and is suitable for use as a material for the production of electrodes, by treating tar middle oil having a b.p. within a specified range with sulfuric acid and adding the separated oil layer to coal tar (pitch). CONSTITUTION:Dilute or concn. sulfuric acid is added to tar middle oil having a boiling range of 80-230 deg.C. The mixture is kept at 150-360 deg.C for 5min to form a substance having a b.p. of 300-420 deg.C. The separated oil layer is washed with an aq. alkaline soln. and added to coal tar or coal tar pitch to obtain the desired tar pitch having a high solid carbon content. The tar pitch is used as a binder for electrodes to give electrodes having excellent bulk specific gravity and physicalproperties.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing tar pitch with an improved fixed carbon content from coal tar with a low fixed carbon content.

(Prior Art) Conventionally, it is known that the fixed carbon content of tar pitch is determined by the fixed carbon content of coal tar, which is a raw material. In other words, the fixed carbon content of the coal tar produced is determined by the type of coking coal charged into the coke oven, the structure of the coke oven, and its operating conditions.For example, as the operating rate of the coke oven increases, the fixed carbon content decreases. becomes higher. Furthermore, this relationship also applies to pitch after distillation. In other words, even if a heat treatment operation is performed after distillation, as long as pitches have the same softening point level, other qualities may differ, but the fixed carbon content remains the same. Therefore, it has conventionally been thought that it is not possible to improve the fixed carbon content in the process of producing tar pitch from coal tar.

(Problems to be Solved by the Invention) The present invention focuses on the points between the above-mentioned conventional techniques and uses coal tar with a low fixed carbon content, and adds additives to it to reduce the fixed carbon content. The purpose is to produce high pitch.

(Means for solving the problem) In order to achieve the above-mentioned object, the present inventors have conducted numerous studies and found that the following are essential requirements: l) Mix diluted sulfuric acid or concentrated sulfuric acid with oil in tar, δ) adding this oil layer to coal tar or tar pitch, dissolving and mixing it, and δ) distilling or heat treating this mixture to produce pitch with improved fixed carbon content. The present invention was achieved by developing a method.

The method for disposing of tar pitches of the present invention uses an oil in tar having a boiling point range of 80 to 280°C, mixes sulfuric acid with the oil in tar, and separates the oil. It is characterized by adding tII# to coal tar or coal tar pitch.

Generally, fractionated oils having various boiling points are produced by distillation of coal tar, but in the present invention, in particular, the fraction in the boiling point range of 80 to 280°C, that is, the oil in tar, is produced. need to use. This is because tar light oil or heavy oil is inherently less effective in improving the fixed carbon content of manufactured tar pitches.

In the method of the present invention, sulfuric acid is mixed with the above-mentioned oil in tar having a boiling point range of 80 to 280°C at a concentration of well over 1 weight.b Generally, sulfuric acid is added to the oil in tar at a ratio of 1 weight or more. ◇ Then, as described above, by holding the mixture of oil in tar and sulfuric acid at a temperature of 15 to 860°C for about 5 minutes or more, the substance having a boiling point of 800 to 420°C is reduced by several percent to 50% by weight. generate. At this time, the higher the sulfuric acid concentration or the higher the holding temperature, the more high boiling point substances are produced. If the sulfuric acid concentration is 1 part by weight or less, high boiling point substances cannot be sufficiently produced. Therefore, in the present invention, as mentioned above, sulfuric acid with a concentration of 1 part by weight or more is used. If too much is produced, the separation between the oil layer and the sulfuric acid layer becomes poor, but by adding a diluting solvent such as benzene to lower the specific gravity of the oil layer and increase the difference in specific gravity with the sulfuric acid layer, high boiling point substances can be removed. The oil layer containing the sulfuric acid layer can be easily separated from the sulfuric acid layer.

Since the fractionated oil containing high-boiling substances thus obtained contains residual sulfuric acid, it is washed with an alkaline aqueous liquid I in an amount of about 5% more by weight in consideration of the problem of equipment corrosion in the subsequent process. The sulfuric acid-treated oil in tar obtained by the alkali treatment is added at a weight ratio of 0.01 to 10 to 1 part of coal tar, and the mixture is distilled or heat-treated to produce pitch.

It was confirmed that the fixed carbon content of the pitch obtained by the sulfuric acid addition treatment as described above was increased by about 8 tatami at the same softening point compared to the pitch not subjected to the sulfuric acid addition treatment.

That is, in the present invention, the tar oil treated with sulfuric acid has the effect of improving the fixed carbon content, and even if the sulfuric acid-treated oil in tar is added to coal tar in the process of producing tar pitch from coal tar, It is also possible to improve the fixed carbon content of the tar pitch produced by adding it to

In general, the carbonization rate of tar pitch used as a caking agent for electrodes or pitch for impregnation for the purpose of densifying electrodes is an important characteristic because it affects bulk specific gravity and physical properties of electrodes. It is said that the higher the fixed carbon content is, the more desirable the fixed carbon content is. By adding sulfuric acid-treated tar oil obtained by adding sulfuric acid at an appropriate concentration to coal tar or pitch, it is possible to improve the fixed carbon content of tar pitches, making it suitable for use in electrode manufacturing. A suitable tar pitch could be produced.

(Example 1) 70 parts by weight of sulfuric acid was blended into tar oil having a boiling point range of 80 to 230°C at a weight ratio of 6:1, and the mixture was stirred and mixed at room temperature for 80 minutes. At this time, the temperature in the liquid rose to 40°C. Thereafter, the mixture was left to stand and separated, and the upper tar oil layer was separated. Furthermore, 5 parts by weight of IJ carbonate solution was added to the tar oil layer at a weight ratio of 10=1, mixed, and separated by standing.

The sulfuric acid-added oil thus obtained was blended at a weight ratio of 1.2 to 1 coal tar, and then a pitch having a softening point of about 80°C was distilled by atmospheric distillation while adjusting the amount of distilled oil. On the other hand, for comparison purposes, the same coal tar without the above-mentioned treated oil was distilled under atmospheric pressure to produce a pitch with almost the same softening point.

Next, the fixed carbon content of pitches with and without treated oil was measured, and the comparison results of these fixed carbon content are shown in Table 1.

From the above table of Table 1, it can be seen that the fixed carbon content of the treated oil-added pitch in this series is about 3 weight higher than that of the non-additive pitch (ordinary pitch).

(Actual m row 2) In the same manner as in Example 1, oil in tar was treated to make pitch. Then, the treated oil after sulfuric acid treatment and alkali washing was distilled off at atmospheric pressure to remove 60 g of the pre-distillate, and the remaining 40 wt.
0 weight attack and 100 weight ill were added respectively to make pitches for the second type competition. Table 2 shows the properties of these pitches.

Table 2 As is clear from Table 2, pitch with added oil has a lower softening point than pitch without additives, but the fixed carbon content increases by 2 to 8 weight range. I understand. Furthermore, it can be seen that the quinoline solvable content did not change.

(Example 8) Oil in tar having a boiling point range of 80-28O<0>C and 70 parts by weight of sulfuric acid were blended in a weight ratio of 5:1. At this mixing stage,
While the reaction vessel was left at room temperature in the actual mflll, the reaction vessel was immersed in a constant temperature bath maintained at 60°C and GO'C, stirring and mixing was performed for 80 minutes, and the upper tar oil layer was separated.

At this time, the temperature in the liquid during mixing is 60℃ in the constant temperature bath.
When the temperature was 75°C, the temperature rose to 95°C when the temperature was 80'C. The subsequent operations were performed under the same conditions as in Example 1 to create a pitch. The results of measuring the fixed carbon content of the obtained pitch were measured in the third
Shown in the table.

#! Table 8 From the above table, it can be seen that when mixing tar oil and sulfuric acid vinegar, the effect of improving the fixed carbon content of pitch can be further enhanced by heating.

(Real [114] Oil in tar with a boiling point range of 80 to 28oC and 4 degrees of sulfuric acid by weight were blended in a weight ratio of 5:1, stirred and mixed at 80oC for 80 minutes, and then separated on a stand. Then, the upper tar oil layer was separated.Furthermore, 5 parts by weight of sodium carbonate solution was added to the tar A/oil layer at a weight ratio of 10=1, mixed, and separated by standing.

The thus obtained treated oil was distilled off at atmospheric pressure to remove 60 weight of the pre-distillate, and the remaining 40 weight of the residue was used as an additive oil, and this added oil was added to coal tar in a weight ratio of 1:1. Afterwards, pitch with a softening point of about 80°C was produced by distillation under atmospheric pressure. On the other hand, the additive-free pitch for comparison is the same pitch as in Example 1.

The measurement results of the softening point and fixed carbon content are shown in Table 4.

It can be seen that in this example, the fixed carbon content of the added pitch was increased by about 2 weights.

Claims (1)

[Claims] 1. Using tar oil with a boiling point range of 80-230℃,
A method for producing tar pitches, which comprises mixing sulfuric acid with the oil in tar and adding the separated oil layer to coal tar or coal tar pitch.