JPH0796266A - Treatment of aluminum dross residual ash and production of cement raw material - Google Patents

Abstract

PURPOSE:To obtain a cement raw material by heating aluminum dross residual ash to a specific temp. under shaking and further heating the same to higher specific temp. to remove nitrogen and chlorine components. CONSTITUTION:Aluminum dross residual ash D is charged in one end part of a rotary kiln 2 arranged in an inclined state from a hopper 3 and the temp. in the rotary kiln 2 is held to 800-1300 deg.C by a burner 4 while the rotary kiln 2 is rotated to heat and stirr the residual ash D. The residual ash D is heated to the specific temp. during this period to be moved to a recovery box 6. After the completion of heating, the burner 4 is controlled to further heat the interior of the rotary kiln 2 to 1300-1600 deg.C. By this constitution, the chlorine and nitrogen components of the residual ash D are removed and alpha-alumina with purity of about 80% or more is received in the recovery box 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating aluminum dross residual ash and a production method for obtaining a raw material for cement from the aluminum dross residual ash.

[0002]

2. Description of the Related Art As is well known, cement, which has a very wide range of uses for construction of civil engineering and building structures,
Calcium oxide (CaO), silicon dioxide (Si
O ₂ ), aluminum oxide (Al ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ) and the like as its main components, and limestone containing calcium oxide, which has the highest content, and silicon dioxide, It is produced by using clay or bauxite containing aluminum oxide, ferric oxide, etc. as a main raw material, and adding silica and iron oxide raw materials to supplement silicon dioxide and ferric oxide.

On the other hand, in the aluminum melting step or the like, aluminum dross is generated as an oxide when aluminum is melted. This aluminum dross is melted again, and about 40% of the aluminum component is recovered by a rotary blade type squeezing machine or the like, and aluminum dross residue containing 50% by weight or less of residual metal aluminum, generally about 40% by weight, is retained. After being made into ash, it is mostly disposed of as industrial waste, but the aluminum nitride etc. remaining in this aluminum dross residual ash reacts with water to generate ammonia and hydrogen chloride, and to generate odors. Since it causes pollution, various pollution-free processing and reuse are being studied.

[0004]

As one method of reusing such aluminum dross residual ash, it is possible to use it as a substitute for the above-mentioned cement clay or bauxite. In such a case, the following method is used. There was a problem. That is, in the aluminum dross residual ash after recovering the aluminum component as described above,
A large amount of aluminum nitride (AlN) remains, and this aluminum nitride is hydrolyzed by moisture such as humidity and rainwater at room temperature as shown by AlN + 3H ₂ O → AL (OH) ₃ + NH ₃ to form ammonia. Is generated, which causes a bad smell. In addition, as a second point, a large amount of chlorine component still remains even after the above-mentioned aluminum component recovery process, and this chlorine component is present in various facilities such as cement manufacturing plants and structures such as metals after actual placement. This is a problem that it has a bad influence on the properties of cement, such as causing corrosion.

Therefore, the present inventors have previously filed Japanese Patent Application No. 5-4.
As proposed in No. 6828, it was found that by heating the aluminum dross residual ash in the temperature range of 1300 ° C to 1600 ° C, the chlorine component can be efficiently vaporized and removed.

However, the aluminum dross residual ash is relatively fine particles, and is composed of oxide particles containing metallic aluminum and metallic aluminum particles that could not be recovered, and the content of metallic aluminum is as described above. When it is high as described above, 40% or more remains. For this reason, when the aluminum dross residual ash is heat-treated in the above-mentioned high temperature range, particles containing metallic aluminum are welded to each other, resulting in the formation of large granular sintered bodies. The molten metal aluminum is oxidized on the surface portion of this lump, and the temperature thereof is rapidly increased to be covered with a semi-molten, solid and dense alumina-based sintered layer. As a result, in the inside of the above-mentioned lump, it was found that due to this dense surface layer, metallic aluminum and aluminum nitride were not sufficiently oxidized and remained, and chlorides were also left without being vaporized.

Then, first, the aluminum dross residual ash was heat-treated at 800 ° C. to 1300 ° C., which is lower than the above temperature range, while stirring the aluminum dross residual ash in the rotary furnace. As a result, 2AlN + 3/2 · O ₂ → Al ₂ O _As represented by ₃ + N ₂ , it has been found that most of aluminum nitride contained in aluminum dross residual ash chemically changes into aluminum oxide and nitrogen gas, and residual metal aluminum is also completely oxidized.

After the above heating, the aluminum dross residual ash is further stirred with 130
0 ° C to 1600 ° C, preferably 1300 ° C to 1450 ° C
When heated to 1, since the aluminum metal was completely oxidized by the heating, the thermite reaction did not occur, and thus the chlorine component could be efficiently and sufficiently removed without solidification. Further, when the above-mentioned aluminum oxide, which occupies about 80% of the obtained treated substance, was examined by X-ray diffraction, they were suitable as raw materials for the cement, had few impure components, and were the most stable among alumina. It was found to be a good quality α-alumina.

The present invention has been made on the basis of the findings obtained in the process of developing such a method for treating aluminum dross residual ash. The present invention oxidizes metallic aluminum in aluminum dross residual ash, and at the same time, chlorine component and nitrogen. It is an object of the present invention to provide a method for producing a raw material for cement that obtains a raw material for cement from the aluminum dross residual ash by using the method for treating aluminum dross residual ash capable of efficiently removing components. .

[0010]

In order to achieve the above object, the method for treating aluminum dross residual ash according to the present invention is mainly intended to remove nitrogen components and oxidize residual metallic aluminum. While shaking the aluminum dross,
C. to 1300.degree. C., preferably 800.degree. C. to 1000.degree. C., in order to remove chlorine components, the aluminum dross residual ash after heating is further heated to 1300.degree. C. to 1600. The heating is carried out in a temperature range of 0 ° C, preferably 1300 ° C to 1450 ° C.

Further, the method for producing a cement raw material according to the present invention comprises oxidizing metal aluminum contained in the aluminum dross residual ash and removing nitrogen and chlorine components by the method for treating aluminum dross residual ash. It is characterized in that α-alumina is obtained and used as a raw material for cement.

Here, the heating temperature is set to 800 ° C. to 130 ° C.
Explaining the reason why the range is limited to 0 ° C, it is 800
If the temperature is lower than 0 ° C, a tentative oxidation removal effect of nitrogen components is observed, but it takes a long time to remove to a satisfactory value, which is not preferable from the viewpoint of treatment efficiency.
This is because, when the temperature exceeds 0 ° C., as described above, the surface portion of the burned body of the aluminum dross residual ash is solidified, and the metallic aluminum and aluminum nitride inside remain without being oxidized.

When the heating temperature is set to 1000 ° C. or lower, the temperature is not higher than the temperature (1050 ° C. or higher) at which the aluminum oxidation reaction rapidly occurs. Therefore, it is possible to reliably prevent the aluminum dross residual ash from solidifying. it can.

Next, the reason why the temperature of the reheating treatment is limited to the above range will be explained. Below 1300 ° C., although a chlorine component removing effect is observed, it takes a lot of time to remove to a satisfactory value. However, the treatment efficiency is not preferable, and when the temperature exceeds 1600 ° C., the chlorine component removing effect becomes saturated, so the range is limited to the above range. At this time, particularly, the temperature of the heat treatment is set to 1300 ° C to 14 ° C.
By setting the temperature in the range of 50 ° C., it is possible to reduce the fuel cost while maintaining the effect of removing the chlorine component, which is preferable.

[0015]

According to the method for treating aluminum dross residual ash according to the present invention, first, the aluminum dross residual ash is shaken, and the temperature is 800 ° C to 1300 ° C, preferably 800 ° C to 1 ° C.
By heating at 000 ° C, the surface of the aluminum dross residual ash powder does not solidify, and the aluminum dross residual ash is converted into aluminum dross residual ash as represented by 2AlN + 3/2 · O ₂ → Al ₂ O ₃ + N _2. Most of the contained aluminum nitride is chemically changed to aluminum oxide and nitrogen gas and removed, and the residual metallic aluminum is also completely oxidized.

Then, the above aluminum dross residual ash is
Similarly, when heated to 1300 ° C. to 1600 ° C., preferably 1300 ° C. to 1450 ° C. with shaking, the residual metallic aluminum remains without being solidified because the residual metal aluminum has already been oxidized by the heat treatment in the previous stage. The chlorine component is sufficiently removed, and a stable treated substance mainly containing α-alumina is obtained.

In this way, the treated substance in which the residual aluminum is oxidized and the chlorine component and the nitrogen component are removed in this way is a high-quality α-alumina which has the least impure component and is the most stable among alumina. Therefore, the above treatment produces a high-quality cement raw material that can substitute for clay or bauxite from the aluminum dross residual ash.

[0018]

EXAMPLES An example of the method for treating the aluminum dross residual ash and the method for producing a cement raw material according to the present invention will be described below. First, an aluminum dross residual ash treatment apparatus / cement raw material production apparatus (hereinafter, simply referred to as a treatment apparatus) suitable for carrying out the method of the present embodiment will be described.

In FIG. 1, reference numeral 1 in the drawing denotes a processing apparatus. This processing apparatus 1 is charged with aluminum dross residual ash D, and a rotary kiln 2 for heating the aluminum dross residual ash D while stirring. And an untreated aluminum dross residual ash D is stored, and the aluminum dross residual ash D is charged into the rotary kiln 2 from one end side thereof, and a dross residual ash hopper 3;
A burner 4 arranged on the other end side of the rotary kiln 2 for heating the inside thereof, a fuel tank 5 for supplying fossil fuel such as heavy oil to the burner 4, and the other end openings of the burner 4 and the rotary kiln 2 are provided. It is roughly configured by a collection box 6 arranged so as to cover it.

The rotary kiln 2 is provided so as to be inclined at a predetermined angle so that one end side thereof is upward, and the aluminum dross residual ash D charged from one end side is stirred as the inclination and the rotation around the axis line occur. At the same time, it is conveyed toward the other end. An exhaust duct 7 is connected to the other end of the rotary kiln 2. Further, a preheater is arranged between the dross residual ash hopper 3 and the rotary kiln 2 as required, and the aluminum dross residual ash D to be fed into the rotary kiln 2
Is preheated.

Next, the processing apparatus 1 thus constructed
An embodiment of the present invention will be described together with the action of. First, the burner 4 is ignited to heat the inside of the rotary kiln 2 to a predetermined temperature, and the rotary kiln 2
Is rotated around the axis at a predetermined rotation speed. From this state, aluminum dross residual ash D is continuously charged from the dross residual ash hopper 3 and the burner 4 is controlled to control the temperature in the rotary kiln 2 to 800 ° C to 1300.
C., preferably maintained in the temperature range of 800.degree. C. to 1000.degree. Then, the aluminum dross residual ash D charged into the rotary kiln 2 from one end thereof is repeatedly heated while being heated to the predetermined temperature, and is repeatedly scraped up by the rotation of the rotary kiln 2 and then dropped. The rotary kiln 2 is gradually fed to the other end side due to the inclination of the rotary kiln 2.

After the above heating is completed, the burner 4 is controlled to control the temperature inside the rotary kiln 2 to 1300.
The aluminum dross residual ash is further heated in a state of being kept in the range of ℃ to 1600 ℃. About 80% or more of the aluminum dross residual ash D conveyed to the other end of the rotary kiln 2 by the above heat treatment is α
-Alumina, which is dropped from the rotary kiln 2 into a recovery box 6 and recovered, and is used as a raw material for aluminum oxide in cement.

Incidentally, clay, which is usually used as a raw material of aluminum oxide for cement, contains silicon dioxide and ferric oxide necessary for the cement in addition to the aluminum oxide. Therefore, when the aluminum dross residual ash is used as a raw material for the cement, in order to supplement these silicon dioxide and ferric oxide components, a larger amount of silica and iron oxide raw material than in the past is added. Will be required.

According to the above-mentioned embodiment, first, the aluminum dross residual ash D is stirred in the rotary kiln 2 to be 800 ° C. to 1300 ° C., preferably 800 ° C. to 10 ° C.
By heat treatment in the temperature range of 00 ° C., the surface portion of the granular material of the aluminum dross residual ash D does not solidify, and as shown by 2AlN + 3/2 · O ₂ → Al ₂ O ₃ + N ₂ , aluminum Aluminum nitride contained in dross residual ash can be completely removed by chemically changing it to aluminum oxide and nitrogen gas.
Residual metallic aluminum can also be completely oxidized.

In addition, the aluminum dross residual ash D, which has been subjected to the above heat treatment, is heated to 1300 ° C. to 1600 ° C. while being stirred in the rotary kiln 2 as well, so that the residual metallic aluminum is already heated by the heat treatment in the preceding stage. Since it has been oxidized, the fired body does not solidify, and as a result, it is possible to obtain a treated substance in which residual chlorine components are efficiently removed.

Moreover, in the treated substance thus obtained, the residual aluminum is oxidized, and the chlorine component and the nitrogen component are removed.
Since it is a high-quality α-alumina containing few impure components and is the most stable among alumina, it can be used as a high-quality cement raw material that can substitute for clay and bauxite.

[0027]

[Experimental Example] Next, based on the above-mentioned example, by heating the aluminum dross residual ash in the temperature range of 800 ° C to 1300 ° C, the residual metallic aluminum in the aluminum dross residual ash is oxidized and the chlorine component is removed. An experimental example showing removal will be described. The contents (%) shown below are all weight%. First, as the aluminum dross residual ash to be treated, 5 kg of aluminum dross residual ash containing 9.7% aluminum nitride (AlN) and 41% residual metallic aluminum was prepared. Then, as a comparative example, the aluminum dross residual ash was heat-treated in an air atmosphere for 5 hours at temperatures of 200 ° C., 400 ° C., and 600 ° C., respectively. As a result, 200
In the heat-treated product at 7.degree. C., aluminum nitride remained at 7.27% and metallic aluminum remained at 41%. Further, the one heat-treated at 400 ° C. had 6.92% aluminum nitride and 33% metallic aluminum remaining, and the one heat-treated at 600 ° C. had 6.58% aluminum nitride and metallic aluminum. 36% remained.

In these comparative examples, the aluminum nitride is not sufficiently oxidized to remove the nitrogen component,
Moreover, it can be seen that the metallic aluminum remains without being oxidized.

Then, next, the aluminum dross residual ash is subjected to 800 times in an air atmosphere for 5 hours, respectively.
Heat treatment was carried out at temperatures of 1000C, 1200C and 1300C. As a result, in the case of heat treatment at 800 ° C., aluminum nitride was reduced to 4.0% and metallic aluminum was also reduced to 22.0%, both of which were greatly reduced. Further, in those heat-treated at 1000 ° C., 1200 ° C. and 1300 ° C., the contents of aluminum nitride are 0.3%, 0.2% and 0.2%, respectively.
The contents of metallic aluminum are 0.9% and 0.
Since it was 9% and 0.8%, respectively, it was found that aluminum nitride and metallic aluminum were almost completely oxidized.

[0030]

As described above, the method for treating aluminum dross residual ash according to the present invention first removes nitrogen components and oxidizes residual aluminum. The aluminum dross residual ash is heated to 800 ° C to 1300 ° C, preferably 800 ° C to 1000 while shaking the ash.
Since the aluminum dross residual ash after heating is further heated in the temperature range of 1300 ° C to 1600 ° C in order to remove the chlorine component by heating in the temperature range of 0 ° C, the aluminum dross residue is not removed. Most of the aluminum nitride contained in the ash can be changed to aluminum oxide and nitrogen gas, and the residual metallic aluminum can be completely oxidized and the chlorine component can be completely removed. Since it is possible to efficiently obtain a treatment substance that does not have a harmful effect due to its components, it is possible to economically reuse the aluminum dross residual ash.

Further, in the method for producing a cement raw material according to the present invention, the residual metallic aluminum is oxidized from the aluminum dross residual ash and the nitrogen and chlorine components are removed by the method for treating the aluminum dross residual ash. , Most of them are aluminum oxide (α-alumina)
Since the treated substance of the aluminum dross residual ash can be obtained, a stable and high-quality aluminum oxide raw material in cement can be produced from the above aluminum dross residual ash.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a processing apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 1 Processing equipment 2 Rotary kiln 4 Burner D Aluminum dross residual ash

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C04B 7/02 7/24 (72) Inventor Mitsuo Fujigo 85 Hiramatsu, Susono-shi, Shizuoka Mitsubishi Aluminum Co., Ltd. Within

Claims (7)

[Claims] 1. The aluminum dross residual ash is shaken while the aluminum dross residual ash is heated at 800 ° C. to 1300 ° C.
After heating in the temperature range of 1300 ° C. to 160 ° C.
A method for treating aluminum dross residual ash, characterized in that the residual metallic aluminum in the aluminum dross residual ash is oxidized and the nitrogen component and chlorine component are removed by heating in the temperature range of 0 ° C. 2. The first heating is performed at 800 ° C. to 100 ° C.
The method for treating aluminum dross residual ash according to claim 1, wherein the method is performed in a temperature range of 0 ° C. 3. The method for treating aluminum dross residual ash according to claim 1, wherein the aluminum dross residual ash contains 50% by weight or less of metallic aluminum. 4. The aluminum dross residual ash is shaken while the aluminum dross residual ash is kept at 800 ° C. to 1300 ° C.
And then heating the aluminum dross residual ash in the temperature range of 1300 ° C to 1600 ° C,
A method for producing a raw material for cement, which comprises oxidizing the residual metallic aluminum in the aluminum dross residual ash and removing the nitrogen component and the chlorine component to obtain α-alumina and use it as a raw material for cement. 5. The aluminum dross residual ash is shaken while the aluminum dross residual ash is kept at 800 ° C. to 1300 ° C.
5. The method for producing a cement raw material according to claim 4, wherein the aluminum dross residual ash is heated in the temperature range of 1300 ° C. to 1450 ° C. 6. The first heating is performed at 800 ° C. to 100 ° C.
The method for producing a cement raw material according to claim 4 or 5, which is performed in a temperature range of 0 ° C. 7. The method of producing a raw material for cement according to claim 4, wherein the aluminum dross residual ash contains 50% by weight or less of metallic aluminum.