KR20190128275A - Method for treating high solid coal tar - Google Patents

Abstract

The present invention relates to a method for treating coal tar having the large amount of solids and, more specifically, to a method for recovering coal tar of which solids are removed from coal tar having the large amount of solids and obtaining coal tar sludge with the low content of quinoline as by-products. The method comprises the following steps: obtaining neutral oil by treating coal tar distillation oil with acids; mixing coal tar having solids and the neutral oil to prepare a mixture; and separating the mixture into a supernatant and coal tar sludge.

Description

Treatment method of coal tar containing a large amount of solids {METHOD FOR TREATING HIGH SOLID COAL TAR}

The present invention relates to a method for treating coal tar containing a large amount of solids, and more particularly, to recover coal tar from which solids have been removed from coal tar containing a large amount of solids, and to obtain coal tar sludge having a low quinoline content as a by-product. It is about a method.

Coal tar, which contains a large amount of solids, is extremely limited in its use as a byproduct during the production of coke used in the steel industry. In general, solids consist of a combination of various substances such as ash, quinoline insoluble (QI), coal, coke and Cenosphere. These solids must be removed from coal tar because they are not suitable for the raw material process for coal tar carbonaceous products. At this time, when the solid content cannot be sufficiently removed from coal tar, it is disposed of or used for fuel.

Conventionally, coal tar containing a large amount of solids is used alone or as a fuel by mixing with petroleum oil. Such coal tar contains more than 0.1 wt% of quinoline. As quinoline is recently designated as a toxic substance, coal tar having a quinoline content of more than 0.1 wt% cannot be used for fuel and must be disposed of.

Under the technical background described above, an object of the present invention is to provide a method for recovering coal tar from which solids have been removed from coal tar containing a large amount of solids and at the same time obtaining coal tar sludge having a low quinoline content as a by-product.

In addition, an object of the present invention is to provide a method for improving the utilization of the raw material coal tar by recovering the coal tar sludge having a low quinoline content and recovering the coal tar from which solids have been removed.

To this end, according to an aspect of the present invention, (a) acid treatment of distillate coal tar to obtain a neutral oil, (b) mixing the coal tar containing solids and the neutral oil to prepare a mixture and ( c) a process for treating coal tar comprising separating the mixture into a supernatant and coal tar sludge.

In addition, according to another aspect of the present invention, (a) acid treatment of the coal tar distillate fraction to obtain a neutral fraction, (b) mixing the coal tar containing solids and the neutral fraction to prepare a mixture, (c) A process for treating coal tar is provided, comprising: separating the mixture into a supernatant and coal tar sludge, and (d) reintroducing the coal tar sludge into step (b).

According to the present invention, coal tar from which coal is removed from coal tar containing a large amount of solids can be recovered and coal tar sludge capable of resourceization can be obtained with a quinoline content lower than the reference value as a by-product.

In addition, according to the present invention, the coal tar sludge having a low quinoline content is re-materialized to be recovered as coal tar from which solids have been removed, thereby improving the utilization of raw coal tar.

1 is a flowchart schematically showing a general coal tar processing method.
2 is a flowchart schematically illustrating a coal tar processing method according to an embodiment of the present invention.
3 is a flowchart schematically showing an acid treatment step of coal tar distillate.
4 and 5 are flowcharts schematically showing a coal tar processing method according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

As used herein, solids refers to solid components generally known to be included in coal tar, such as ash, quinoline insoluble (QI), coal, coke, Cenosphere and the like.

As used herein, coal tar sludge is similar to coal tar containing a large amount of solids, but the term coal sludge means sludge including solids as a by-product generated in a separation process for recovering coal tar.

Methylnaphthalene herein means mixed use of isomers such as 1-methylnaphthalene and 2-methylnaphthalene without distinction.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

1 is a flowchart schematically showing a conventional coal tar processing method.

Referring to FIG. 1, a general coal tar treatment method includes coal tar containing a large amount of solids alone and coal tar sludge with a large amount of solids removed by centrifugation, super decanting, or settling. Coal tar and coal tar distillate or petroleum kerosene containing a large amount of solids are mixed to prepare a mixture, and then the mixture is separated into coal tar from which solids are removed and coal tar sludge with a large amount of solids separated by a separation process.

At this time, when the coal tar containing a large amount of solid alone is separated into a solid portion and a liquid portion, when the solid is concentrated, there is a problem in that the viscosity becomes high and transfer is impossible. In addition, since the quinoline contained in the coal tar is also included in the coal tar sludge, the quinoline content of the coal tar sludge is more than 0.1 wt%, so it is difficult to reuse or recycle it.

In addition, when a mixture of coal tar containing a large amount of solids and untreated coal tar distillate is used, the effect of removing quinoline from coal tar sludge is minimal due to quinoline present in the coal tar distillate. In addition, when petroleum oil is used instead of coal tar distillate, coal tar recovery efficiency is not preferable.

2 is a flow chart schematically showing a coal tar treatment method according to an embodiment of the present invention, Figure 3 is a flow chart schematically showing an acid treatment step of coal tar distillate.

Referring to Figure 2, the coal tar treatment method according to an embodiment of the present invention comprises the steps of (a) acid treatment of distillate coal tar to obtain a neutral oil, (b) by mixing the coal tar containing the solid content and the neutral oil Preparing a mixture and (c) separating the mixture into a supernatant and coal tar sludge.

Step (a) is an acid treatment of the coal tar distillate to obtain a neutral oil free of quinoline.

Coal tar distillate fraction refers to an oil fraction obtained by distilling coal tar, and generally refers to an oil having a boiling point of 200 ° C to 400 ° C. The oils in the boiling point range from 200 ° C to 400 ° C include naphthalene, methylnaphthalene (1-methylnaphthalene, 2-methylnaphthalene), quinoline, Acenaphthene, Dibenzofuran, Anthracene, and Phenanthrene.

As used herein, the coal tar distillate may include 20 wt% or more methylnaphthalene, and more preferably, the coal tar distillate may include 25 wt% or more methylnaphthalene. If the content of methylnaphthalene is less than 20wt%, coal tar recovery efficiency may be lowered.

In addition, the oil in the boiling point 200 ℃ to 400 ℃ region may include a tar salt such as quinoline, isoquinoline, indole and the like. Such tar salts can be further recovered in subsequent processes to further enhance the economic value of the raw materials. Accordingly, the coal tar distillate used herein preferably comprises at least 0.2 wt% quinoline.

Acids used for acid treatment of coal tar distillate include hydrochloric acid, sulfuric acid, nitric acid, zeolites, activated carbon, and the like. When using hydrochloric acid, sulfuric acid, or nitric acid, it is preferable to use a dilute acid solution having a concentration of 1% to 30%. Do.

When the coal tar distillate and the acid solution are mixed by a mixing method such as stirring to prepare a mixture and then separating the mixture, the mixture is separated into a neutral oil layer from which tar salts are removed and a layer (water layer) containing tar salts. Can be.

The tar salt may be neutralized with a basic material such as sodium hydroxide and then extracted to obtain a material such as quinoline, isoquinoline or the like by a distillation process.

The neutral oil included in the neutral oil layer from which the tar salt is removed may include 20 wt% or more of methylnaphthalene and may contain 0.1 wt% or less of quinoline. At this time, the content of quinoline in the neutral fraction may be preferably 0.08 wt% or less, more preferably 0.05 wt% or less.

That is, by treating the coal tar distillate fraction, quinoline can be selectively removed while maintaining the content of methylnaphthalene in the distillate fraction.

Subsequently, step (b) is a step of preparing a mixture by mixing a coal oil containing quinoline-free neutral oil and a large amount of solids.

Here, coal tar includes solids such as ash, quinoline insoluble (QI), coal, coke, Cenosphere, and the like, and the content of solids may be 7% to 35%. When the content of solids in the coal tar exceeds 35%, the difficulty of recovering the coal tar from which the solids have been removed rapidly increases, and it is preferable to use coal tar having a solid content of 35% or less.

At this time, the mixing ratio of coal tar and neutral oil is preferably 1: 0.2 to 1: 2. If the neutral oil is used in less than 0.2 parts by weight of coal tar, there is a fear that the recovery efficiency of the coal tar is removed, the content of quinoline contained in the separated coal tar sludge may exceed 0.1wt%. On the other hand, if neutral oil is used in an amount greater than 2 parts by weight of coal tar, the recovery efficiency of coal tar can be improved, and the content of quinoline contained in the separated coal tar sludge can be maintained at 0.1 wt% or less, but there is a concern that the process economy will be lowered. have.

The mixing of coal tar and a large amount of quinoline-free neutral oil containing a large amount of solids can be carried out by various known stirring methods. For example, in order to use decanting as a separation method, it is preferable to mix at 40 to 120 degreeC, and to use to settling, it is preferable to mix at 100 to 300 degreeC.

Subsequently, the mixture prepared by mixing coal tar containing a large amount of solids and neutral oil free of quinoline is separated into a supernatant and coal tar sludge (step (c)).

The mixture can be separated into supernatant and coal tar sludge by methods such as centrifugation, super decanting, stationary settling and the like.

The higher the temperature upon centrifugation, super decanting or settling, the better the solvent is not evaporated, for example, it may be carried out in a temperature range of about 20 to about 150 ° C. In addition, the centrifugal force during centrifugation may be about 1,500G to about 10,000G. The greater the value of the centrifugal force (G-force), the higher the solids removal rate from coal tar and the recovery rate of coal tar from the raw material.

The supernatant separated through this separation method includes coal tar from which solids have been removed, and the content of coal tar in the supernatant separated in step (c) may be 30% to 90% of the raw coal tar in step (b). The content of coal tar in the supernatant separated in step (c) is the content of methylnaphthalene in the neutral oil used in step (b), the content of neutral oil mixed with the raw coal tar in step (b), and the amount of neutral oil used in step (c). It can be variously adjusted according to the separation method and separation conditions.

In addition, the content of solids contained in coal tar in the supernatant separated in step (c) may be 7wt% or less, preferably 5wt% or less, and more preferably 3wt% or less. Generally, solids in the recovered coal tar are mostly QI (Quinoline insoluble), which is separated from the coal tar by the general subsequent treatment process (distillation, etc.), and then remains in the coal tar pitch.

Meanwhile, the quinoline content in the coal tar sludge separated in step (c) is 0.1 wt% or less, and may be reused or recycled because the quinoline content is lower than the reference value. In addition, the viscosity of the coal tar sludge separated in step (c) is 800 cP or less at 80 ℃, can be easily transported by a pump or the like.

4 and 5 are flowcharts schematically showing a coal tar processing method according to another embodiment of the present invention.

Referring to Figure 4, the coal tar treatment method according to another embodiment of the present invention (a) acid treatment of distillate coal tar to obtain a neutral oil, (b) by mixing the coal tar containing the solid and the neutral oil Preparing a mixture, (c) separating the mixture into a supernatant and coal tar sludge, and (d) reintroducing the coal tar sludge into step (b).

According to the invention, the coal tar sludge separated in step (c) may contain coal tar not recovered.

Accordingly, in step (d), coal tar sludge containing unrecovered coal tar can be re-injected and used in step (b), in which case it is possible to improve the utilization rate of the raw coal tar.

At this time, the coal tar sludge may be used by mixing with coal tar containing a large amount of solids or by replacing coal tar containing a large amount of solids.

In addition, the utilization rate of the raw material coal tar can be further improved by repeating steps (b) to (d) several times. The number of repetitions of steps (b) to (d) may be appropriately selected in consideration of the content or viscosity of solids contained in coal tar sludge.

Referring to Figure 5, the coal tar treatment method according to another embodiment of the present invention comprises the steps of (a) the acid treatment of distillate coal tar to obtain a neutral oil, (b) mixing the coal tar containing the solid and the neutral oil Preparing a mixture, (c) separating the mixture into a supernatant and coal tar sludge, (d) mixing the coal tar sludge separated in step (c) with the neutral oil obtained in step (a). And (e) separating the mixture prepared in step (d) into a supernatant and coal tar sludge.

The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention is not limited thereto.

Example 1

A mixture was prepared by stirring and mixing 40 parts by weight of a 10% concentration sulfuric acid solution to 100 parts by weight of coal tar distillate containing 28 wt% of methylnaphthalene and 1.3 wt% of quinoline at room temperature. The prepared mixture was separated and separated into an upper neutral layer and a lower moisture layer, from which tar salt components were removed. The quinoline content in the neutral fraction was 0.02 wt%.

The water layer in the lower layer was added with an equivalent amount of sulfuric acid, stirred, and mixed, followed by separating an oil layer containing a tar salt component and a water layer in which sodium sulfate was dissolved.

The mixture was prepared by stirring and mixing 100 parts by weight of neutral oil at 100 parts by weight of raw coal tar including 25% solids at a temperature of 80 ^° C. for 30 minutes. The prepared mixture was placed in a centrifuge and maintained for 5 minutes at a centrifugal force of 3000 G-force.

The separated supernatant was distilled under reduced pressure at a pressure of 0.1 kg / cm ² and a temperature of 240 ^° C. to separate neutral oil to recover coal tar.

Coal tar was recovered by 50% of the raw coal tar, the solid content of the recovered coal tar was 0.4%. The viscosity of the bottom coal tar sludge of the centrifuge was 250 cP at a temperature of 80 ^° C., and the quinoline content was 0.08 wt%.

Example 2

100 parts by weight of neutral oil prepared in the same manner as in Example 1 to 100 parts by weight of raw coal tar including 18% solids was stirred and mixed at a temperature of 150 ^° C. for 30 minutes to prepare a mixture.

The prepared mixture was introduced into a stationary settler in a nitrogen atmosphere at a temperature of 150 ^° C. and 5 kg / cm ² pressure, and allowed to stand for 2 hours. The supernatant was separated at a flow rate of 70% by volume relative to the input flow rate of the stationary settler.

The separated supernatant was distilled under reduced pressure at a pressure of 0.1 kg / cm ² and a temperature of 240 ^° C. to separate neutral oil to recover coal tar.

Coal tar was 60% of the raw coal tar was recovered, the solid content of coal tar was 3%. The viscosity of the lower coal tar sludge in the stationary settler was 310 cP at a temperature of 80 ^° C., and the quinoline content was 0.06 wt%.

Example 3

A mixture was prepared by stirring and mixing 50 parts by weight of a neutral oil prepared in the same manner as in Example 1 to 100 parts by weight of raw coal tar including 25% solids at a temperature of 80 ^° C. for 30 minutes.

The prepared mixture was placed in a primary centrifuge and maintained for 10 minutes at a centrifugal force of 3000 G-force. The viscosity of the lower coal tar sludge of the first centrifuge was 330 cP at a temperature of 80 ^° C.

A mixture was prepared by stirring and mixing 50 weights of the neutral oil prepared in the same manner as in Example 1 to 100 weight parts of the lower layer coal tar sludge of the first centrifuge at a temperature of 80 ^° C. for 30 minutes.

The prepared mixture was placed in a secondary centrifuge and maintained for 10 minutes at a centrifugal force of 3000 G-force. The viscosity of the lower coal tar sludge of the secondary centrifuge was 220 cP at a temperature of 80 ^° C., and the quinoline content was 0.03 wt%.

The supernatant separated in the primary centrifuge and the secondary centrifuge was distilled under reduced pressure at a pressure of 0.1 kg / cm ² and a temperature of 240 ^° C. to remove neutral oil to recover coal tar. The recovered coal tar recovered 70% of the raw coal tar, and the solid content in the coal tar was 0.2%.

Comparative Example 1

The mixture was prepared by stirring and mixing 100 parts by weight of coal tar-based absorbent oil at a temperature of 80 ^° C. for 30 minutes to 100 parts by weight of coal tar including 25% solids.

The prepared mixture was introduced into a centrifuge and separated for 10 minutes with a centrifugal force of 3000 G-force. The separated supernatant was distilled under reduced pressure at a pressure of 0.1 kg / cm ² and a temperature of 240 ^° C. to separate absorbent oil to recover coal tar.

The recovered coal tar recovered 50% of the raw coal tar, and the solid content in the coal tar was 0.7%. The viscosity of the lower coal tar sludge of the centrifuge was 230 cP at a temperature of 80 ^° C., and the quinoline content was 0.85 wt%.

According to Comparative Example 1, when the coal tar-based absorbent oil, which is a kind of general coal tar distillate, was used as the solvent, it was confirmed that the quinoline content of the lower layer coal tar sludge was higher than the reference value (0.1 wt%).

Comparative Example 2

A mixture was prepared by stirring and mixing 100 parts by weight of petroleum kerosene in 100 parts by weight of coal tar including 25% solids at a temperature of 80 ^° C. for 30 minutes.

The prepared mixture was introduced into a centrifuge and separated for 10 minutes with a centrifugal force of 3000 G-force. The separated supernatant was distilled under reduced pressure at a pressure of 0.1 kg / cm ² and a temperature of 260 ^° C. to separate petroleum kerosene to recover coal tar.

The recovered coal tar recovered 15% of the raw coal tar, and the solid content in the coal tar was 0.3%. The viscosity of the bottom coal tar sludge of the centrifuge was 580 cP at a temperature of 80 ^° C., and the quinoline content was 0.57 wt%.

According to Comparative Example 2, since petroleum kerosene does not mix well with the raw coal, the recovery of coal tar is low and the quinoline content of the lower coal tar sludge is higher than the reference value (0.1 wt%).

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

Claims (10)

(a) acid treating the coal tar distillate to obtain a neutral fraction;
(b) preparing a mixture by mixing coal tar including solids and the neutral oil; And
(c) separating the mixture into a supernatant and coal tar sludge;
Including;
The quinoline content in the coal tar sludge separated in step (c) is 0.1 wt% or less,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
In step (a), the content of quinoline in coal tar distillate is at least 0.2 wt%, the content of quinoline in neutral fraction is at most 0.1 wt%,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
Step (a) is
Mixing the coal tar distillate with an acid solution to prepare a mixture; And
Separating the mixture into a layer comprising a neutral oil layer from which tar salts are removed and a tar salt;
Including,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
Coal tar in step (b) comprises from 7% to 35% solids,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
In step (b), the mixing ratio of coal tar and neutral oil is 1: 0.2 to 1: 2,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
The content of coal tar in the supernatant separated in step (c) is 30% to 90% of the coal tar in step (b),
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
The content of solids contained in coal tar in the supernatant separated in step (c) is 7wt% or less,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
The viscosity of the coal tar sludge separated in step (c) is not more than 800 cP at 80 ℃,
A method of treating coal tar containing a large amount of solid content.
The method of claim 1,
Preparing a mixture by mixing the coal tar sludge separated in step (c) with neutral oil; And
Separating the mixture into a supernatant and coal tar sludge;
Further comprising,
A method of treating coal tar containing a large amount of solid content.
(a) acid treating the coal tar distillate to obtain a neutral fraction;
(b) preparing a mixture by mixing coal tar including solids and the neutral oil;
(c) separating the mixture into a supernatant and coal tar sludge; And
(d) re-charging the coal tar sludge to step (b);
Including;
The quinoline content in the coal tar sludge separated in step (c) after re-injection is 0.1 wt% or less,
A method of treating coal tar containing a large amount of solid content.

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