JP2000290529A - Process for treating oxidized carbon black and carbon black treating device used for this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient process for removing deleterious by-products from a carbon black which was oxidized using a nitrogen-containing oxidizing agent, and a device and a treatment process suitable for this. SOLUTION: In a process for treating oxidized carbon blacks, oxidized by- products are removed from the oxidized carbon blacks by heating the oxidized carbon blacks in a device. The device is equipped with a casing which possesses multiple trays having a slit part which are aligned in the vertical direction. Each tray has a scraper which scrapes off the powder from the tray via the slit to transfer the powder from the upper tray to the lower tray. A hot air is allowed to flow through the casing to heat the powder on the tray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a processing apparatus and a processing method for removing harmful by-products from carbon black oxidized using a nitrogen-containing oxidizing agent.

[0002]

2. Description of the Related Art It is known that carbon black is oxidized to impart an acidic functional group to the surface to improve dispersion in various vehicles, and ozone, nitric acid, nitric oxide and the like are known as oxidizing agents. ing. The functional groups and the properties of the surface introduced by the oxidation of carbon black have not yet been sufficiently elucidated, and there are differences in the expression of the physical properties of the oxidized carbon black obtained depending on each oxidizing agent and oxidizing conditions.

[0003] Nitrogen-containing oxidizing agents such as nitric acid and nitric oxide are useful for obtaining oxidized carbon black having good physical properties. However, when these nitrogen-containing oxidizing agents are used, harmful oxidation by-products remain in the carbon black and need to be removed. Conventionally, carbon black is oxidized by putting carbon black into a heating device such as a rotary kiln, introducing a gas flow and an oxidizing agent into the carbon black, oxidizing the carbon black, and then introducing a gas such as air. A method for removing oxidation by-products from the surface of carbon black by heating while heating is known (JP-B-44-5691).

[0004]

However, such a conventional technique has the following problems. In such a method for removing harmful oxidation by-products by supplying air into a device such as a rotary kiln and contacting it with carbon black at a predetermined temperature, the flow rate of gas introduced into the device to increase efficiency is When the carbon black is increased, the carbon black powder is blown out of the kiln along with the gas flow, and it is difficult to adjust the residence time of the carbon black in the kiln. In order to increase the amount of air introduced per unit time per unit weight of carbon black to increase the production amount, and to secure a predetermined residence time, it is necessary to increase the apparatus diameter and the apparatus length, There is a problem that equipment costs, maintenance costs, and the like are high.

[0005] In addition, although a certain temperature or more is required to remove oxidation by-products, it is necessary to increase the heat conduction area inside the kiln in order to efficiently raise the temperature of carbon black in the kiln. . In the method using a kiln, a device having a heat transfer tube in the kiln is used to heat the carbon black by heat transfer from the heat transfer tube. It is necessary to increase the number of internal heat transfer tubes, etc., which complicates the kiln internal structure and inevitably causes fine irregularities.
Problems such as blockage occur.

When removing by-products from carbon black oxidized with a nitrogen-containing oxidizing agent, an exothermic reaction occurs, and the temperature of the carbon black increases. Since carbon black flows in the kiln in the axial direction, in order to adjust the temperature of the heated carbon black, lower the amount of hot air introduced into the kiln, lower the temperature of hot air, or lower the temperature of the body jacket. There is no other way. According to these methods, when the carbon black is continuously introduced into the kiln, the temperature of the carbon black on the inlet side is lowered to that of the carbon black that has just entered the kiln, resulting in a very poor efficiency. Driving is also difficult.

[0007] In the case of batch operation, an additional service tank is required, which increases the cost. It is also difficult to discharge products. SUMMARY OF THE INVENTION An object of the present invention is to provide an efficient method for removing harmful by-products from carbon black oxidized by using a nitrogen-containing oxidizing agent, and a suitable apparatus and processing method. An object of the present invention is to provide a device free from adhesion or the like.

[0008]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems. As a result, they have found an apparatus and a method that are simple and inexpensive in structure and that can efficiently remove harmful by-products from oxidized carbon black. That is, according to the present invention, (1) a plurality of trays each having a slit portion are provided in a casing in a vertical direction, and each tray sweeps powder on the tray from the slit, thereby lowering the tray from the upper tray. Heating the oxidized carbon black in a device that has a scraper for moving to the tray and heats the powder on the tray by circulating hot air through the casing, thereby oxidizing by-products from the carbon black A method for treating carbon oxide, which removes oxidized by-products from carbon oxide black, wherein (2) the method for treating carbon oxide black according to (1), wherein air is passed in parallel to the tray;

(3) The air flowing in parallel on the tray is
(1) The method for treating oxidized carbon black according to the above (1) or (2), which has a hot air flow area and a cooling water area, (4) flowing air at a gas linear velocity of 0.05 to 1.0 m / sec. (5) The method for treating oxidized carbon black according to any one of (1) to (4), wherein the temperature of air is controlled so that the temperature of oxidized carbon black is 100 to 180 ° C. A method for treating oxidized carbon black according to

(6) The method for treating oxidized carbon black according to any one of (1) to (4), wherein the thickness of the deposited layer of carbon black is 50 mm or less, (7) a slit is provided in the casing. A structure that has a plurality of trays in the vertical direction, each tray has a scraper that sweeps and moves the powder on the tray, and heats the powder on the tray by flowing hot air through the casing. (8) The apparatus for treating oxidized carbon black according to (7), wherein the tray has a disk shape, (9) the carbon black is oxidized with a nitrogen-containing oxidizing agent, and 8) The method for producing oxidized carbon black, characterized in that the nitrogen-containing oxidizing agent is removed to 100 ppm or less by treating in the treatment apparatus described in 8).

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
The type of carbon black to be treated in the present invention is not particularly limited. The carbon black typically includes, but is not limited to, a furnace black obtained by a furnace method and a channel black obtained by a channel method. In particular, furnace black is relatively inexpensive and is generally distributed in large quantities, but carbon black produced in a production furnace often has an insufficient amount of acidic functional groups on the surface, and is not suitable for oxidation treatment. Often provided. The carbon black may be in the form of powder in the state of being recovered from a carbon black production furnace, in the form of granules obtained by dry granulation or wet granulation of the powder, or in the form of flakes obtained by a compression operation. Things and the like,
In the present invention, the carbon black can be used without any particular limitation. However, from the viewpoint of reaction efficiency, powdery carbon black is generally preferably used.

As the oxidizing agent used in the oxidation treatment, ozone, nitric acid, and nitrogen oxide are typical. Particularly, when oxidizing using nitrogen oxide such as nitric acid or nitric oxide, various kinds of by-products are produced. It is known that nitrogen-containing compounds remain in carbon black. Therefore, it is necessary to remove them.

In the present invention, the removal is performed by treating the carbon black in a specific device. The treatment is to remove the adhered components by stirring, and furthermore,
Achieving effects obtained by stirring carbon black in the apparatus, such as efficient removal of adhering components by heating while stirring. The term "stirring" as used herein means that the carbon black is moved by a scraper in the apparatus or is mixed while falling from the upper tray to the lower tray.

This device has a casing, a tray having a slit portion, and a scraper. The casing forms the outer shell of the device. A plurality of trays having slit portions are present in the vertical direction in the casing. The scraper sweeps the powder on the tray so that the powder falls from the slit of the tray and falls on the lower tray. That is, the powder gradually moves from the upper tray to the lower tray among the plurality of trays in the casing. At that time, hot air is circulated in the casing, and the powder on the tray is heated by the hot air while moving.

An example of an apparatus that can be suitably used in the present invention will be described below with reference to FIGS. FIG. 1 is a schematic longitudinal sectional view showing an example of the processing apparatus of the present invention. In the figure,
1 is a powder supply nozzle and 2 is a powder discharge nozzle. Reference numeral 3 denotes a hot air air inlet nozzle. From here, hot air is introduced into the device. As the hot air to be introduced, air heated by a heat exchanger or the like may be used. The temperature of the air may be determined based on the charged amount, the amount of water, and the like so as to obtain a desired carbon temperature.

Reference numeral 4 denotes an outlet nozzle for hot air introduced from the inlet nozzle for hot air. Reference numerals 5 and 6 denote airflow adjusting damper valves for adjusting the flow of air. 7 is a cooling air introduction nozzle, and 8 is a cooling air outlet nozzle. Reference numerals 9 and 10 are air flow adjusting damper valves for adjusting the flow of the cooling air. Reference numeral 11 denotes a main body casing, which is preferably in a cylindrical shape, and is preferably made of a metal material such as mechanical structural steel and stainless steel, which is resistant to corrosion and structural strength.

Reference numeral 13 denotes a tray plate for loading carbon black, which is generally preferably disk-shaped. Twelve holes are formed at equal angles as shown in the plan view of FIG.
The sheet is conveyed to a tray plate below L.
The positions of the holes are designed so that the positions are slightly different in each tray plate. Reference numeral 12 denotes a hollow shaft for fixing and rotating the tray plate 13. As the 12 hollow shafts rotate, the 13 disc-shaped tray plates rotate, and are transferred to the tray plate below the holes 26a to 26L by the fixed 24 scraper. By performing similar operations sequentially in the lower direction, heat can be efficiently transmitted to the carbon black. A desired number may be selected depending on the size of the 26-hole device.

The number of the 13 tray plates may be determined according to the desired carbon black residence time. The size of the plurality of trays located in the up-down direction may be determined based on the desired residence time and processing amount of carbon black. In addition, the number may be determined in consideration of the number of trays and the amount of carbon black deposited per tray. If the number of trays is too small, the effect of stirring the carbon black powder is reduced, and the effect of removing by-products is reduced.

Reference numeral 14 denotes a lower bearing of 12 hollow shafts, 15 denotes a gear for transmitting rotation to the 12 hollow shafts, 15 denotes a driving gear, and 17 denotes a prime mover. Reference numeral 18 denotes a drive shaft for rotating 20 turbo fans. 19 is an upper bearing, 20 is a turbo fan, and 12 hollow shafts have openings between the circular tray plates that do not reduce the strength, so that the internal fan can efficiently flow the internal air flow. Become. Reference numeral 21 denotes a reduction gear, and reference numeral 22 denotes a prime mover, which has a structure for rotating a fan through a chain of 23.

FIG. 2 is a plan view of 13b in FIG. 24
Is a scraper for scraping carbon black from the holes 26 of the tray plate 13. Reference numeral 25 denotes a layer thickness adjusting plate for adjusting the carbon black dropped from the powder supply nozzle 1 and the hole 26 of each tray plate 13 to a uniform layer thickness. Numeral 26 is a rectangular tray provided with a rectangular carbon black drop hole which is radially formed at an equiangular angle. There are 12 such holes from 26a to 26L.

The vertical relationship between the trays and the opening 26 will now be described with reference to FIG. FIG. 3 is an image diagram showing the flow of the movement of the powder from the upper tray to the lower tray.
As shown in FIG. 3, the holes are opened little by little so as to be present in each of the trays 13a to 13d, and the dropped carbon black is adjusted to a desired thickness by a 25-layer thickness adjusting plate. After that, about one rotation, the scraper 24 falls on the lower tray. 27a is a carbon black powder deposited state after falling, and 27b is a carbon black powder adjusted to a desired layer thickness by a layer thickness adjusting plate. The same operation is performed sequentially, and the lower part is extracted from the lowermost part. If the thickness of the carbon black is too thick, the heat of the hot air is transmitted only to the surface layer of the deposited layer, resulting in poor efficiency. The thickness is preferably 50 mm or less. Preferably 10 to 40 m
m is good. More preferably, if it is 25 to 35 mm, by-products can be efficiently removed.

It has been clarified that carbon black to which a nitrogen compound adheres generates heat when the nitrogen compound is desorbed by contact with hot air. For this reason, it is possible to control the carbon black to a desired temperature range by appropriately introducing hot air and cold air so as not to raise the temperature excessively, thereby suppressing excessive heat generation. Introducing nozzle 7 for cooling air in FIG.
By introducing cold air from the nozzle and discharging it from the cooling air discharge nozzle 8, it is possible to prevent the temperature of the carbon black from rising above a desired temperature. A plurality of cooling air introduction nozzles 7 may be provided at appropriate disc-shaped tray intervals to control the temperature of carbon black.

The flow direction of the hot air is preferably parallel to the tray. Hot air is flowed in parallel to the deposited carbon black, and is scraped off from the disc-shaped tray by a scraper to obtain the effect of stirring. At this time, if the flow rate of the hot air is small, the effect of removing the by-products is small. Therefore, the flow velocity of hot air is 0.05 ~
1 m / sec is good. Preferably 0.1 to 0.6 m / s
ec, more preferably 0.15 to 0.4 m / sec. The scattered carbon black may be collected by a solid-gas separator such as a bag filter and returned to the supply side. However, if this amount is large, the equipment cost increases. Therefore, it is desirable to operate at a desired gas flow rate that does not scatter as much as possible.

In order to remove by-products adhering to carbon black, it is necessary to keep the carbon black powder under desired temperature conditions. This temperature is 100 to 100 in the case of removing nitrogen-containing compounds by-produced by oxidation with nitric acid or the like.
180 ° C. When the temperature is preferably 120 to 160 ° C, more preferably 130 to 150 ° C, by-products can be efficiently removed. The apparatus and processing method of the present invention
_{(2) It} can be removed to 100 ppm or less as the degree of removal.
Furthermore, it can be removed to 50 ppm or less. As the processing apparatus of the present invention described above, a commercially available multi-stage flash dryer used for drying powders such as resin pellets, sugar, and starch can also be used.

[0025]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. (Example 1) "# 47" manufactured by Mitsubishi Chemical Corporation was oxidized by the following method. A mixed gas having a nitric acid gas concentration of 5.0% by volume obtained by evaporating 70% nitric acid in air is preheated to 100 ° C., and a gas flow of 10 m / sec is set at a gas temperature of 10%.
It is circulated in a pipe controlled at 0 ° C., and is dispersed by an ejector while quantitatively supplying carbon black at a rate of 240 g / min such that nitric acid is 15.0 parts by weight with respect to 100 parts by weight of carbon black. After the carbon black was oxidized with the residence time in the pipe being 20 seconds, the gas flow accompanying the carbon black was cooled to 50 ° C., and the gas after the reaction and the oxidized carbon black were separated in the collection bag. Obtained oxidized carbon black (NO ₂ amount
20,000 ppm) was introduced into a multi-stage flash dryer ("2011 type" manufactured by Showa Kakoki Co., Ltd.) as schematically shown in FIGS. 1 to 3 to remove oxidation by-products. The processing conditions are as follows.

Supply amount of carbon black: 160 to 300 kg / hr Temperature of carbon black: 150 to 160 ° C. Dry gas flow rate: 0.3 m / sec Number of trays: 11

For the above oxidized carbon black, the NO ₂ amount of the treated oxidized carbon black collected from the powder discharge nozzle 2 was measured. As shown in Table 1, 30
It was confirmed that NO ₂ could be removed up to 28 PPM in minutes. The measurement method of NO ₂ is JISk-0104 ”
It was measured using a zinc reduced naphthylethylenediamine method (NEDA method), which is a method for analyzing nitrogen compounds in exhaust gas.

[0028]

[Table 1]

[0029]

As described above, in the case of a conventional horizontal rotating device such as a kiln, it is necessary to increase the installation area, and the size of the device itself is increased, and the manufacturing cost is increased. The residence time of carbon black in the kiln is determined by the angle of the blades in the kiln and the flow velocity and direction of the gas flowing inside, but this adjustment is necessary for powders with a low bulk density such as carbon black. difficult. On the other hand, according to the processing apparatus of the present invention, since a multi-stage cylindrical structure can be used, the site area can be reduced, and the residence time of carbon black can be designed and adjusted by adjusting the number of tray plates. There are advantages such as simplicity and simplicity of the structure, and low production cost. In the kiln, it is difficult to adjust the temperature of the carbon black at each part in the flow direction. However, the processing apparatus of the present invention measures the temperature of the carbon black on each tray plate with a thermocouple or the like and adjusts the temperature to a predetermined temperature. The temperature of the carbon black can be controlled by controlling the temperature of the air introduced into the casing. In addition, by adjusting each inlet valve, the amount of hot air flowing through each tray plate can be adjusted, and by-products can be efficiently removed.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing an example of a processing apparatus of the present invention.

FIG. 2 is a plan view of 13b in FIG.

FIG. 3 is an image diagram showing a flow of powder moving from an upper tray to a lower tray.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G070 AA01 BB21 CA25 CB18 DA21 4J037 AA02 CA08 CA18 DD20 EE02 EE19 EE25 EE28 EE33 EE47 EE48 FF05

Claims (9)

[Claims] 1. A casing has a plurality of trays having a slit portion in a vertical direction in a casing, and each tray sweeps powder on the tray from a slit so that the tray is placed on a tray lower than an upper tray. Removing oxidized by-products from carbon black by heating the oxidized carbon black in a device having a scraper to be moved and capable of heating the powder on the tray by flowing hot air through the casing; A method for treating oxidized carbon black, comprising removing oxidized by-products from oxidized carbon black. 2. The method for treating carbon oxide black according to claim 1, wherein air is circulated in parallel with the tray. 3. The method for treating carbon oxide black according to claim 1, wherein the air flowing in parallel on the tray has a hot air flow region and a cooling flow region. 4. The air has a gas linear velocity of 0.05 to 1.0 m /
The method for treating carbon oxide black according to any one of claims 1 to 3, which is circulated in seconds. 5. The temperature of the oxidized carbon black is 100 to 100.
The temperature of air is controlled so as to be 180 ° C.
A method for treating oxidized carbon black according to any one of claims 1 to 4. 6. A carbon black deposited layer having a thickness of 50
The method for treating oxidized carbon black according to any one of claims 1 to 5, which is not more than mm. 7. A casing has a plurality of trays having slits in a vertical direction in a casing, and each tray has a scraper for sweeping and moving powder on the trays,
A carbon oxide black processing apparatus having a structure capable of heating powder in a tray by flowing hot air through a casing. 8. The apparatus for treating carbon oxide black according to claim 7, wherein the tray has a disk shape. 9. Oxidation wherein carbon black is oxidized with a nitrogen-containing oxidizing agent, and the carbon black is treated in the processing apparatus according to claim 7 to remove the nitrogen-containing oxidizing agent to 100 ppm or less. A method for producing carbon black.