KR101748110B1 - Process for the recovery of cobalt oxide from the residues in the dmt process - Google Patents

Abstract

The present invention relates to a method for recovering concentrated cobalt oxide by treating a cobalt tar generated as a by-product in a process for producing dimethyl terephthalate (DMT) by a low-temperature thermal reaction and a magnetic separation process, wherein the cobalt tar is pulverized To obtain granular cobalt tar; A primary heat reaction step of thermally reacting the granular cobalt tar obtained in the pulverizing step with the primary heat reaction furnace at a temperature of 260 ° C or lower to evaporate and separate the DMT component contained therein to obtain a primary concentrated cobalt ingot; Pulverizing the primary concentrated cobalt ingot obtained in the primary thermal reaction step to a granular grain of not more than 5 mm and selectively concentrating the tar and tar-containing cobalt contained in the primary concentrated cobalt ingot under strong magnetic field to obtain tar cobalt; The cobalt oxide was recovered from the residues of the DMT production process as a second thermal reaction step in which tar cobalt obtained in the magnetic separation step was thermally reacted at 260 ° C or less in a secondary thermal reaction furnace to evaporate and separate the contained DMT components to obtain concentrated cobalt do.
As a result, cobalt tar, which is a residue of the DMT manufacturing process, is concentrated and recovered by low temperature thermal reaction and strong magnetic field lines without conventional incineration treatment or wet chemical treatment, The emission of pollutants hardly occurs.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for recovering cobalt oxide from a residue of a process for producing dimethyl terephthalate (DMT)

The present invention relates to a method for recovering cobalt oxide from residues of dimethyl terephthalate (hereinafter referred to as "DMT"), and more particularly to a method for recovering cobalt oxide from a residue of a high purity And a method for recovering cobalt oxide.

DMT is widely used as a raw material for polyester polymers, polyester fibers, films and molded products, together with Purified Terephtalic Acid (PTA).

There are various methods for producing DMT. Among them, the Witten process is widely used because it does not use a solvent and its reaction conditions are mild and easy to enlarge. It is also called a 4 stage air oxidation method because it is subjected to a 4-step reaction process.

In the DMT production process, when P-xylene is oxidized with air at 200-210 ° C and 12-25 ATM in the presence of an acetic acid catalyst containing cobalt, manganese and bromine, PTA is produced by a liquid phase reaction, When methanol is reacted with PTA, DMT is obtained. At this time, cobalt tar containing heavy metals such as cobalt as a byproduct of DMT process is generated as a residue.

Cobalt is one of the transition metals and is used not only as a catalyst in the process of producing DMT / PTA but also in various fields such as Li-ion battery, cemented carbide, super magnet and dye. However, It is rare metal.

Thus, several methods for recovering cobalt from process residues (cobalt tar) are known. For example, in Korean Patent No. 10-0575192, sodium hydroxide (NaOH) is added to a waste catalyst liquid to adjust the pH of the waste catalyst liquid to 4 to 6, and the waste catalyst liquid is introduced into a reaction settler; Introducing a slurry of sodium bicarbonate (NaHCO3) prepared by mixing sodium bicarbonate (NaHCO3) and water into a reaction settler to which the spent catalyst is added; Heating the slurry of sodium bicarbonate (NaHCO3) mixed with the spent catalyst to perform a chemical reaction and a precipitation reaction; And recovering the metal precipitate by filtering the reaction solution of the chemical reaction and the precipitation reaction. The method of recovering cobalt and manganese from spent catalysts in the production of terephthalic acid is disclosed. However, such a recovery method by liquid phase reaction has a problem of causing secondary environmental pollution due to a waste liquid containing cobalt generated in the process.

As another example, U.S. Pat. No. 4,464,477 discloses a process for the preparation of a mixture comprising para-xylon and methylditoluene in liquid form in the DMT process of Witten, in the presence of a dissolved heavy metal oxidation catalyst, Oxygen-containing gas, and then the oxidation product is esterified with methanol under high temperature and high pressure. The high boiling point distillation residue is mixed with water or a dilute aqueous solution of water-soluble low molecular aliphatic monocarboxylic acid at 70 to 160 ° C to extract and the extract is returned to the oxidation step, A method for recovering and reusing an oxidation catalyst containing cobalt and / or manganese from a residue characterized by recycling the high boiling distillation residue and the extractant, which is recovered and reused. Such a recovery method by the liquid phase reaction has a problem of causing secondary environmental pollution due to the waste liquid containing cobalt generated in the treatment process.

In another example, the process residue (cobalt tar) is treated as a general waste and incinerated, and the ash is chemically treated to produce cobalt sulfate or cobalt chloride. However, in the incineration treatment method, a large amount of carbon dioxide is generated at the time of incineration, and there is a risk of scattering of cobalt oxide in the atmosphere. Such cobalt is known to be toxic to the respiratory system, digestive system, nervous system, eyes, ears and skin due to inhalation or exposure, as well as reproductive / teratogenic, genotoxic, mutagenic and carcinogenic toxicants.

1. Korean Patent Registration No. 10-0450528 (November 26, 2004) 2. Korean Registered Patent No. 10-0575192 (April 28, 2006) 3. Korean Patent No. 10-1083351 (November 15, 2011) 4. United States Patent 4,410,449 (October 18, 1983) 5. U.S. Pat. No. 4,464,477 (August 07, 1984) 6. U.S. Pat. No. 4,609,634 (September 02, 1986)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a recovery method that does not generate secondary environmental pollution and air pollutants during the extraction of cobalt components from residues of the DMT production process.

It is an object of the present invention to accomplish a low temperature thermal reaction of cobalt tar which is a residue of a DMT manufacturing process and a process of concentrating and recovering cobalt components by strong magnetic field lines.

The concentrating and recovering step includes a crushing step of crushing cobalt tar into particles of 5 mm or less to obtain granular cobalt tar; A primary heat reaction step of thermally reacting the granular cobalt tar obtained in the pulverizing step with the primary heat reaction furnace at a temperature of 260 ° C or lower to evaporate and separate the DMT component contained therein to obtain a primary concentrated cobalt ingot; A step of grinding the primary condensed cobalt ingot obtained in the primary thermal reaction step to a granular particle of 5 mm or less and selectively concentrating the tar and tar-containing cobalt contained in the primary concentrated cobalt ingot under strong magnetic field to obtain tar cobalt; And a second heat reaction step of thermally reacting the tar cobalt obtained in the magnetic force selection step at 260 ° C. or less in the secondary heat reaction furnace to evaporate and separate the contained DMT component to obtain concentrated cobalt.

And a granular cobalt tar of 5 mm or less is obtained by using a crusher in the pulverization step.

The first heat reaction furnace in the first heat reaction stage is tubular, and the DMT component discharged from the tubular furnace in the gaseous phase is cooled to 40 ° C or lower by the cooling means and is recovered by the cyclone dust collector.

Further, the magnetic field of the magnetic force selecting step is characterized by being 7,000 to 9,000 Gauss (G).

And the secondary heat reaction furnace in the secondary heat reaction stage is a tunnel type.

According to the present invention, cobalt tar, which is a residue of the DMT manufacturing process, can be concentrated and recovered by low-temperature thermal reaction and strong magnetic field lines without conventional incineration treatment or wet chemical treatment, So that there is almost no emission of air pollutants due to the air pollution.

1 is a process flow diagram showing a preferred embodiment of the present invention.
2 is a block diagram of the cobalt tar used in the crushing step of FIG.
FIG. 3 (a) is a view showing a primary thermal reaction disposed in a process of the primary thermal reaction step of FIG. 1, and FIG. 3 (b) is a photograph showing a primary cobalt ingot.
FIG. 4A is a DMT cooling line connected to the primary thermal reaction furnace of FIG. 3A, and FIG. 4B is a DMT photographed. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a process flow chart showing a preferred embodiment of the present invention. The method for recovering cobalt oxide from the residues of the DMT production process of the present invention comprises a DMT production process containing about 5.0 to 6.0 wt% of a cobalt component Of cobalt tar is concentrated and recovered with a cobalt oxide component of 80.0 wt% or more per low temperature thermal reaction and strong magnetic field lines.

As shown in FIG. 1, the concentration and recovery process includes a crushing step of crushing cobalt tar into particles of 5 mm or less to obtain granular cobalt tar; A primary heat reaction step of thermally reacting the granular cobalt tar obtained in the pulverizing step with the primary heat reaction furnace at a temperature of 260 ° C or lower to evaporate and separate the DMT component contained therein to obtain a primary concentrated cobalt ingot; A step of grinding the primary condensed cobalt ingot obtained in the primary thermal reaction step to a granular particle of 5 mm or less and selectively concentrating the tar and tar-containing cobalt contained in the primary concentrated cobalt ingot under strong magnetic field to obtain tar cobalt; And a second thermal reaction step of thermally reacting the tar cobalt obtained in the magnetic force selection step at 260 ° C or less in a secondary thermal reaction furnace to evaporate and separate the contained DMT component to obtain concentrated cobalt.

In the cobalt tar, for example, at least 90 wt% of cobalt tar is composed of a DMT component, and fluorine (F), manganese (Mn), and the like are added to the cobalt tar. , And contains about 5.5 wt% of cobalt (Co). The cobalt tar has irregular sized masses as shown in the photograph of FIG. Such cobalt tar is crushed into granules of 5 mm or less using a crusher to promote a uniform thermal reaction and a reaction rate.

The granulated cobalt tar after the pulverization step is continuously fed into the hopper directly connected to the primary heat reaction furnace by the conveyer conveying means and subjected to the first thermal reaction step. FIG. 3A is a photograph showing a primary reaction furnace. The primary heat reaction furnace is a tubular furnace in which a tube having a diameter of about 300 mm is arranged long, and a conveying means for moving the cobalt tar introduced into the hopper to the opposite side of the hopper.

For example, the conveying means may be a spiral-type rotary screw closely attached to the inner wall, or a system in which the tubular body is rotated by providing the tubular body at a predetermined slope. FIG. 3A is a photograph showing the primary heat reaction furnace. The granular cobalt tar charged into the hopper of the primary heat reaction furnace shown in the photograph is heated and moved in the opposite direction to the hopper. At this time, it is preferable to arrange the first-order thermal reaction furnace in two or more stages in order to secure a residence time of 10 minutes or more.

In addition, the first heat reaction furnace is an indirect heating method in which a heat source such as hot wire is externally heated to maintain the internal temperature at a low temperature of about 260 ° C., thereby evaporating the DMT contained in the granular cobalt. In order to sufficiently evaporate DMT, it is preferable that the granular cobalt tar is allowed to move for about 10 minutes in the first heat reaction furnace.

 Particulate cobalt tar is evaporated from the DMT contained in the granular cobalt tar in the primary heat reaction during the stay at a low temperature of about 260 ° C in the primary heat reaction furnace, and the cobalt oxide component is concentrated to about 17.0 wt%. Figure 3b shows a primary cobalt ingot exiting the primary heat reactor exiting the exit. As shown in the photograph, the granular cobalt tar charged in granules of 5 mm or less in the first reactor is aggregated into irregular masses again.

As described above, the granular cobalt moves inside the first-order thermal reaction furnace and evaporates DMT contained in the gas phase. The DMT component, which is vaporized in the gaseous phase, is cooled to 40 ° C or lower while passing through a cooling duct exposed to the air in the discharge process. FIG. 4A is a photograph showing a cooling line arranged and connected to the rear end of the primary thermal reaction furnace. In the case of 300 mm in diameter of the first reaction furnace and 60 m 3 / hour of DMT gas flow, the diameter of the cooling line is preferably 150 mm .

The primary cobalt ingot injected in the magnetic force selection step is solidified into an irregular mass as shown in FIG. 3B. Therefore, in order to effectively perform the magnetic force selection, the primary cobalt ingot must be crushed to a predetermined particle size. The primary cobalt ingot is charged into the hopper by a double screw conveyor to crush the ingot, and crushed into granules of 5 mm or less. The primary cobalt ingot that has been crushed to a granular shape of 5 mm or less passes through, for example, a roller type magnetic separator to induce cobalt oxide, which is a ferromagnetic substance, and allows the non-magnetic tars to pass therethrough.

The granular cobalt ingot of 5 mm or less, which is attracted to the magnetic separator, is concentrated to about 46.0 wt% of tar cobalt by the cobalt oxide content. In this case, the magnetic field of the magnetic separator is preferably a strong magnetic field of 7,000 to 9,000 Gauss (G) in order to attract the cobalt oxide dispersed in the primary cobalt ingot crushed into granules of 5 mm or less.

The second thermal reaction step is a process of further concentrating cobalt by evaporating DMT which is still remaining in tar cobalt concentrated to 46.0 wt% of cobalt oxide in the magnetic separation step. In order to further concentrate the cobalt, tar cobalt is introduced into the secondary heat reaction furnace. In this case, the secondary heat reaction furnace is preferably a batch type or a tunnel type for intermittently treating a certain amount of cobalt. The secondary thermal reaction furnace is maintained at about 260 DEG C to evaporate the DMT remaining in the tar cobalt. When the tar cobalt is allowed to stay in the secondary heat reaction furnace for about 10 to 20 minutes, the DMT component contained therein is evaporated, and 80.0 wt % Or more of concentrated cobalt oxide can be obtained. The DMT components evaporated and discharged in the gaseous phase in the secondary thermal reaction furnace are cooled to 40 ° C or less by cooling means such as air in the discharge process, the DMT cooled to 40 ° C or less is changed to powder, and the powdered phase- And collected by a clone dust collector. At this time, the recovered tar can be supplied as fuel for the plasma incinerator.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (5)

A method for extracting and recovering a cobalt component from cobalt tar which is a residue generated in a process for producing dimethyl terephthalate (DMT)
Crushing the cobalt tar into particles of 5 mm or less to obtain granular cobalt tar;
A primary thermal reaction step of thermally reacting the granular cobalt tar obtained in the pulverizing step at 260 ° C or less in a primary thermal reaction furnace to evaporate and separate the contained DMT component to obtain a primary concentrated cobalt ingot;
The first concentrated cobalt ingot obtained in the first thermal reaction step is pulverized into granules having a size of 5 mm or less and the tar and cobalt-containing cobalt contained in the primary concentrated cobalt ingot are selectively concentrated under strong magnetic field to obtain tar cobalt ;
The second step of the thermal reaction in which tar cobalt obtained in the magnetic force selecting step is subjected to a thermal reaction at 260 ° C or less in a secondary thermal reaction furnace to evaporate and separate the contained DMT components to obtain concentrated cobalt, A method for recovering cobalt oxide from water.
The method according to claim 1,
And recovering cobalt oxide from the residue of the dimethyl terephthalate (DMT) production process, wherein granular cobalt tar having a size of 5 mm or less is obtained by using a crusher in the crushing step.
The method according to claim 1,
Wherein the DMT component discharged in the gaseous phase from the tubular furnace is cooled to 40 ° C or lower by the cooling means and is recovered by the cyclone dust collector. A method for recovering cobalt oxide from a residue of a phthalate (DMT) production process.
The method according to claim 1,
Wherein the magnetic field of the magnetic force selecting step has a magnetic field of 7,000 to 9,000 Gauss (G).
The method according to claim 1,
Wherein the second heat reaction furnace in the second heat reaction step is a tunnel type, and the cobalt oxide is recovered from the residue of the step of producing dimethyl terephthalate (DMT).

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