JPH1179801A - Method for producing alumina cement from aluminum residual ash - Google Patents

Abstract

(57) [Abstract] [Objective] The object of the present invention is to use aluminum residual ash with an aluminum content of 20% or more and less than 40% by-products of aluminum secondary alloy manufacturers that can only be disposed of as an alumina cement raw material. To make it available. SOLUTION: Alumina cement is obtained by mixing an aluminum residual ash containing 20 to 40% of aluminum with a calcareous raw material, and promoting a thermite reaction while pulverizing lump unreacted substances generated in a firing or melting step of the mixture. It is characterized by manufacturing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for processing 20 to 4
The present invention relates to an innovative method for producing a useful alumina cement using aluminum residual ash containing 0% of aluminum.

[0002]

2. Description of the Related Art Aluminum residue ash, which has been produced by-products of aluminum alloy manufacturers, is partially used as a heat insulator and slag-making agent for iron and steel. Depends on the situation. In addition, aluminum ash for steel manufacturers is preferred to have relatively high aluminum content from the purpose of use, and the aluminum content is specified in the pick-up conditions. At present, the above demand is small.

[0003] In order to minimize the melting of impurities (especially iron) in the scrap to be melted, aluminum secondary alloy manufacturers operate with a low aluminum melting temperature. Therefore, in the process of recovering molten aluminum from the dross scraped up from the melting furnace (ashing process), since the temperature of the dross is low, the aluminum in the dross should be recovered in a short time with good yield in accordance with the cycle time of the operation. Is difficult, and residual ash containing about 30 to 60% of aluminum is mainly generated.

[0004] The secondary alloy maker analyzes the aluminum content of the aluminum residual ash produced through the ash squeezing process, and if the aluminum content satisfies a specified value, sells it to a steel maker, and the aluminum ash that does not meet the specified value is sold. Residual ash is disposed of, but since aluminum residual ash contains a considerable amount of aluminum nitride and aluminum carbide, ammonia gas and hydrocarbon gas are generated when it comes in contact with moisture, which generates odors. Requires attention. In addition, disposal sites have recently been decreasing, and there is an urgent need for reuse.

Therefore, paying attention to the composition of aluminum residual ash,
By mixing aluminum residual ash and calcareous raw materials and firing or melting in a rotary kiln, aluminum nitride is decomposed,
A method for producing an alumina cement containing calcium aluminate as a main component has been proposed. A method for producing this kind of cement from aluminum residual ash and calcareous raw materials is disclosed in Japanese Patent Application Laid-Open Nos. 52-152929 and 54-6.
No. 5726, JP-A-63-28893, JP-A-7-5
Research has already been made as described in JP-A Nos. 3244 and 7-53246. However, the residual aluminum ash used in these studies is not of the type generated by the above-mentioned aluminum secondary alloy manufacturers, but is a dross reclaimer (= a professional supplier that regenerates aluminum from dross by squeezing) or aluminum Aluminum residue ash generated from a furnace that dissolves high-purity scrap is used, and the aluminum content is 20% or less. This is considered to be due to the following reasons. By the way, in the case of aluminum residual ash coming out of a dross reclaimer, in general, ashing is performed at a high temperature without considering the dissolution of impurities into recycled aluminum.
The residual ash has a low aluminum content of 5 to 20%.

When aluminum residual ash having a high aluminum content is mixed with a calcareous raw material and fired in a rotary kiln such as a cement kiln, the thermite reaction which proceeds with heat during the oxidation of metallic aluminum proceeds rapidly, and Becomes a lump, and its surface reacts at high temperature, but the inside of the lump becomes unreacted and remains as it is. In addition, the surface of the lumps easily adheres to the furnace wall in a molten state, and if adhered and grown on the furnace wall, continuation of the operation is hindered. Therefore, in view of these problems, it is considered that the above-mentioned research uses aluminum residual ash with little aluminum content.

In order to calcine aluminum residual ash and decompose aluminum nitride in aluminum residual ash,
It is necessary to maintain the furnace temperature at 700 ° C. or higher, and generally, the furnace is operated at 1100 ° C. or higher to increase the reaction rate.
However, using aluminum residual ash with a small amount of aluminum and firing at a high temperature as described above requires a lot of fuel, and further costs such as pulverizing the fired material into cement-like fine powder. In total, it is difficult to manufacture economically as a product.

[0008]

The aluminum ash with an aluminum content of 20% or more and less than 40% by-produced by a secondary aluminum alloy maker is difficult to handle as an alumina cement raw material for the above-mentioned reason. I have to do it. On the other hand, it is economically difficult to economically produce an alumina cement containing calcium aluminate as a main component by using aluminum residual ash having a small amount of aluminum alone. Against this background, the problem to be solved by the present invention is to reduce the fuel cost in the firing process by using aluminum residual ash which has been difficult to fire when the aluminum content is 20% or more and less than 40%, and is economically efficient. The aim is to develop a method of manufacturing alumina cement that can be used.

[0009]

According to the present invention, there is provided a method according to claim 1, wherein "a mixture of aluminum residual ash containing 20 to 40% of aluminum and a calcareous raw material is used in the firing or melting step of the mixture. The alumina cement is manufactured by promoting the thermite reaction while pulverizing the generated unreacted mass. "

[0010] According to this, aluminum residual ash having a high aluminum content of 20 to 40% is used as a raw material, and the raw material which has become a lump during the firing is fired while being pulverized, so that the firing is accelerated and the aluminum is removed. By using the aluminum ash with a large content, calcination can be advanced by efficiently utilizing the heat generated by the thermite reaction, and thereby the fuel cost can be saved.

The aluminum residual ash used here is a by-product from the melting process of various aluminum scraps by an aluminum alloy manufacturer, the aluminum content of which is 20% to 40%.
Aluminum ash less than 2, but aluminum content is 2
When using low aluminum content residual ash of 0% or less,
It is sufficient if a high aluminum content material such as aluminum chips is added and the total aluminum content is 20% or more and less than 40%. In addition, a high aluminum content residue ash having an aluminum content of more than 40% may be used instead of a high aluminum content material such as aluminum chips, or conversely, a low aluminum content residue ash may be added to the high aluminum content residue ash. May have an aluminum content of 20% or more and less than 40%.

The calcareous raw materials to be added include limestone [CaCO ₃ ], slaked lime [Ca (OH) ₂ ], and quick lime [CaO]. Strictly speaking, the addition ratio of calcareous raw materials is aluminum residual ash (main components are Al, Al
Si, Si in ₂ O ₃ , Si, SiO ₂ , Mg, MgO)
Although it varies depending on the content of O ₂ , Mg and MgO, it is generally blended by the following method. That is, when the aluminum residual ash and calcareous raw material are calcined, the oxide (Al
₂ O ₃ , CaO, SiO ₂ , MgO, etc.). Then, part of these oxides react to produce 2CaO.Al ₂ O _3.
SiO ₂ and MgO.Al ₂ O ₃ are formed, and the remainder forms various combined CaO.Al ₂ O ₃ . Then, As an example of the addition ratio of the calcareous material to aluminum residual ash, the CaO · Al ₂ O ₃ of the various conjugates can _{3CaO · Al 2 O 3, 12CaO} · 7Al 2 O 3, C
is formulated to form _{aO · Al 2 O 3, CaO} · 2Al 2 O 3.

The aluminum residual ash and the calcareous raw material to be blended are uniformly pulverized and mixed by a ball mill or the like in order to assist the reaction in the firing process. This mixture is fired or melted at about 1100 to 1500 ° C. in a rotary kiln to obtain a cementitious clinker. At this time, SiC, SiC,
A ceramic ball or refractory brick having high thermal shock resistance made of N or the like as a raw material is inserted into a furnace and rotated together with the raw material. The obtained clinker is pulverized to obtain a hydraulic material mainly composed of calcium aluminate.

[0014]

The present invention will be described below in detail. To a residual aluminum ash (A) and (B) containing an aluminum metal component (= Met-Al) shown in Table 1, calcium carbonate powder was added as a calcareous raw material at a weight ratio shown in Table 2, and the mixture was placed in a ball mill. Then, the mixture was crushed in a rotary kiln, and baked under the baking conditions shown in Table 2 with a residence time in the furnace of 2 hours. Table 3 shows the state of firing when operating under each firing condition.

As is clear from the comparison between Inventive Example-1 and Comparative Example-1, Inventive Example-1 has the same fuel efficiency as Comparative Example-1 fired using aluminum residue ash having a low aluminum content. , High furnace temperature is realized. Therefore, if the temperature in the furnace is the same, the fuel cost can be saved correspondingly. Further, as is apparent from the comparison between Inventive Example-2 and Comparative Example-2, the adhesion to the furnace wall caused when firing was performed using aluminum residue ash having a high aluminum content was eliminated by charging the crushed balls. ing.

The fired product obtained in Inventive Example-2 was pulverized by a ball mill so that the 200 mesh sieve residue (74 μm or more) was less than 5%. 60 parts by weight of water was added to 100 parts by weight of the pulverized product, kneaded, put into a mold having a diameter of 3 cm and a height of 5 cm, cured, and then demolded to obtain a molded product.
One week after kneading, the molded body was subjected to a compression strength test. For comparison, a similar molded body was prepared for a commercially available alumina cement No. 1, and a compression test was performed. Table 4 shows the results of the compression test. As a result of the compression test, strength equivalent to that of a commercially available alumina cement was obtained.

<< Table 1 Aluminum content (wt%) of aluminum residual ash subjected to test >> Met-Al residual ash-A 19.2 residual ash-B 29.9

<< Table 2 Blending and firing conditions >> Aluminum used Blending weight Pulverized ball Mixing rate Rate of residual metal ash Amount ratio With / without (kg / hr) Comparative example-1 No A 28 Comparative example-2 Aluminum residual ash: No 6 46 Invention Example-1 B Calcium carbonate: 4 Yes 39 Invention Example-2 Yes 50

<< Table 3 Conditions of Firing >> Maximum temperature in furnace (° C.) Heavy oil consumption (L / kg) Adhesion to furnace wall Comparative Example-1 1328 2.00 None Comparative Example-2 1440 1.02 Yes invention Example-1 1436 1.95 None Invention Example-2 1447 0.96 None

<< Table 4 Results of Compression Test (kgf / cm^Two) >>Invention Example-2 135 Alumina cement No. 1 137  The analysis values of Inventive Example-2 were as follows. << Analytical value of invention example-2 wt /% >>CaO Al ₂ O ₃ SiO ₂ Fe ₂ O ₃ MgO Other 23.6 58.5 8.2 2.9 6.1 0.7

[0021]

According to the present invention, aluminum residual ash containing 20 to 40% of aluminum, which had to be discarded in the past, can be used for refractories and civil engineering building materials without impairing economy and workability. It can be reused for cement.

Claims (1)

[Claims] An aluminum residue ash containing 20 to 40% of aluminum and a calcareous raw material are mixed, and a lump unreacted substance generated in a firing or melting step of the mixture is pulverized to promote a thermite reaction while promoting a thermite reaction. A method for producing alumina cement from aluminum residual ash, characterized by producing cement.