JPS5930716A - Method for utilizing aluminum ash - Google Patents

Abstract

PURPOSE:To utilize effectively aluminum ash by dissolving the ash in an aqueous soln. of NaOH to form sodium aluminate while recovering generated gas and by adding sodium silicate to the resulting soln. to convert the sodium aluminate into zeolite. CONSTITUTION:Aluminum ash produced as a by-product during the refining of Al or an Al alloy is dissolved in an aqueous soln. of NaOH having 10-50% concn., and water is added to dilute the soln. about 1.5-2 times. After adding gluconic acid, alkali gluconate, sorbitol or the like as required, the soln. is allowed to stand and filtered to remove insoluble matter. Sodium silicate is added to the resulting filtrate (sodium aluminate soln.), and zeolite is formed by vigorous stirring for about 6-7hr. Gas generated during the formation of sodium aluminate is recovered and utilized. The gas consists of about 90-99.9% H2, about 0.1-2% CH4 and the balance NH3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively utilizing aluminum ash.

Aluminum oxide, which is suspended in the molten metal when aluminum or aluminum alloy is melted in a rumbo or industrial furnace,
In order to remove brick powder or hydrogen gas dissolved in the molten metal, an appropriate flux is added, and the so-called aluminum ash, which is mainly composed of aluminum oxide, that floats on top of the molten metal is scraped out of the furnace. However, at this time, a part of the molten metal is drawn in, and in some cases, aluminum ash containing 50% or more of metallic aluminum may be taken out.

This aluminum ash, commonly referred to as secondary ash or secondary dross, is sent to a reclamation zone plant where a reclamation zone is produced from the fraction rich in metallic aluminum. Recycled aluminum in this case too? So-called secondary ash, which is mainly composed of aluminum oxide and floats above the fI hot water, is taken out.

This secondary ash also contains 50 to 40% of granular metal aluminum with a diameter of 2 to 5 mm, and the granular metal aluminum is separated using a sieve with a mesh size of 2 or less, and the aluminum is recycled by melting it again. While producing a lump, the aluminum oxide ash floating on top of the molten metal is removed. This ash is generated in a slightly larger amount than the secondary ash mentioned above, and is called tertiary ash or residual ash.

The tertiary ash may also contain 20% or more of metallic aluminum fine particles with a diameter of 0.50 or less, but it is necessarily economically difficult to regenerate metallic aluminum from this tertiary ash, and it is not necessary to dispose of it by dumping. There are also the following problems when doing so.

In other words, when high-temperature molten metal is treated with chlorine or other fluxes, when metallic aluminum partially exceeds 10,000 due to an exothermic reaction, nitrogen in the air and some metallic aluminum combine to form aluminum nitride. AltJ + 5H, o-+At(OH)s + NH3
・・・・・・−・−・・・・・・・−・・・ (1) At4C
3+12F(,O→4At(OH)s+5CH4・
・・・・・・・・・(2) Methane and ammonium gas are generated, and the metal aluminum fine particles, which have become high temperature due to the accumulation of reaction heat, cause an oxidation reaction with oxygen in the air, and partially 5000 If the temperature rises above ℃ and ignites, a phenomenon called electricity is generated, and there is a risk of explosion if water is poured in to extinguish the fire, so manufacturers of recycled lumps consider it a nuisance and spend a large amount of money to dispose of it by dumping it in seawater, etc. Disposed of by.

The present invention has been made in view of the above-mentioned poetic sentiments, in order to provide a more effective method of utilizing primary, secondary, and tertiary aluminum ash.

That is, in the present invention, sodium aluminate is produced by dissolving any one or more of the above-mentioned primary, secondary, and tertiary ash in a 10 to 50% caustic soda solution, and then silicon is added to the sodium aluminate solution. Synthetic zeolite is produced by adding acid soda, or aluminum hydroxide is produced by precipitation of aluminum hydroxide by adding seed crystals after diluting the sodium aluminate with water, or the gas generated during the production of the above sodium aluminate is produced. The present invention relates to a method of utilizing aluminum ash, which is characterized in that it is recovered.

The method of the present invention will be explained in detail below, but for reference, an example of the components of the above-mentioned aluminum 9mm primary, secondary, and tertiary ash (hereinafter simply referred to as primary ash, secondary ash, and tertiary ash) is shown below. Shown in Tables 1 to 5.

(Note 1) In addition to oxygen, a trace amount of nitrogen is included.

(Note 2) Calculated by multiplying by weight ratio.

Table 2 (Example of components of secondary ash) Table 5 (Example of components of tertiary ash) In the method of the present invention, secondary, secondary, and tertiary ash contain trace amounts of aluminum nitride, aluminum carbide, and silicide in addition to metallic aluminum. Of course, it is necessary to use ash that contains aluminum (each of which dissolves in caustic soda) and has a high content of metallic aluminum, but due to metallurgical technology and economical reasons, it is impossible to recover metallic aluminum quickly. It goes without saying that it is economically preferable to use . However, from the filtration yield after dissolving in the caustic soda solution, 1 % of aluminum soluble in the caustic soda solution is
It is preferable to use those containing 0- or more, preferably those having the quality shown in Item 2 of Table 6.

A caustic soda solution with a concentration of 10% or less can be used, but in the case of producing synthetic zeolite, it is necessary to concentrate by evaporation etc. after dissolving the primary, secondary, and tertiary ash, so the concentration is 10% or less in terms of energy efficiency. A concentration of ~50%, preferably 20-25% is used. The amount of caustic soda solution used is 400 to 6 per 40 g of soluble aluminum.
Approximately 0.00 tel is preferable. In addition, since tertiary ash dissolves in caustic soda solution with a rapid reaction, in order to prevent bath loss, either tertiary ash or caustic soda solution is added to the other in small amounts over a long period of time. It is desirable to do so.

After the primary, secondary, and tertiary ash have been completely dissolved in the caustic soda solution, filtration is performed, and in order to facilitate this filtration operation, the ash is diluted with water.

The dilution ratio is preferably about 1.5 to 2.0 times the total amount.

In addition, before filtration, the liquid is allowed to settle, and during this settling, gluconic acid or It is desirable to add at least one of tartaric acid or its alkali salt, triethanolamine, and sorbitol. By adding these compounds, it is possible to prevent the oxidation of low-valent Fe dissolved in the solution (Japanese Patent Application No. 57-45680).
(see issue). The amount of these compounds (hereinafter referred to as antioxidants) to be added is preferably about 5 to 59 G per 16 of the solution.

Furthermore, when using low-grade ash with a soluble aluminum content of 50% or less, a large amount of undissolved matter will be suspended in the solution after dissolution is completed, but if this suspension does not settle down even after a long period of time, After addition of the above-mentioned antioxidant, an organic flocculant (for example, an acrylamide-based hydrolysis product, etc., product name: Himorok 3) that acts even under alkaline conditions with a pH of 14 or higher
8-120, SS-L50.88-140, etc.) from 10 to
It is possible to add about 50 ppm.

After adding the above-mentioned antioxidant and organic flocculant, the solution obtained by filtration contains, in addition to these agents, approximately 1 to 4 units of NaC/;, 1 unit or less of alkali fluoride, etc. Although it exists,
Regardless of the presence of these, high-grade synthetic zeolite (1.Tl54A in this case) can be produced by adding sodium silicate (for example, No. 5185) by a known method.

By adding aluminum hydroxide as a seed crystal instead of sodium silicate and stirring at room temperature for 4 days or more, high purity aluminum hydroxide can be produced by the so-called Bayer method. In this case, if the amount of seed crystals added is too small, there will be no effect, and if it is too large, it will be meaningless, so 0.05 to
．． 0197 is preferable.

Furthermore, in the method of the present invention, when the primary, secondary, and tertiary ash described above is dissolved in a caustic soda solution, a large amount of gas is generated at the same time as sodium aluminate is produced. This gas varies slightly depending on the raw material ash used, but in general,
H290~999chi, CH2O, 1~2゜0chi, NI(
This gas is also collected at the same time because it has a composition of 3 and can be effectively used for various purposes.

Various known methods can be used to recover the gas. For example, in a method of storing the gas in the upper space of a water tank, the entire amount of NH, is absorbed into the water, and H2 containing a trace amount of CH, can be recovered.

Note that the amount of H and gas generated when producing 1 ton of synthetic zeolite can be calculated using Zeolite X 2 .

The method of the present invention will be demonstrated below using experimental examples.

Experiment 1 (1) Dilute 250 mt of 48% caustic soda solution to about 500 ml and put it in an evaporating dish with a diameter of 50 am, and add a small amount of Mitsukisei shown in 1 ml of Table 5 into this! 4
．． When about 1 to 2 g of aluminum was gently added, the metal aluminum in the tertiary ash suddenly caused an exothermic reaction and was dissolved in the caustic soda solution while generating gas. The reaction at this time is thought to occur according to the following formula.

At+ Na0F(+H,O→NaAt0.+H
, -- (4) Continue to add a small amount of Mibukisei, and when the violent reaction that occurs after the addition has finished, repeat the operation of adding a small amount of Mibukisei again, and in about 50 minutes, the Mibukisei will reach 100V. The total amount of Mibuki-Nari that was inputted (at the time when the input of 10091 was completed,
Since the caustic soda solution was in a boiling state due to the heat of reaction, water was added to bring the total volume to 800 mA.

In addition, approximately 59% sodium gluconate was added to prevent the formation of aluminum hydroxide due to hydrolysis of the generated sodium aluminate and to prevent the oxidation of dissolved Fe.

After leaving for about 48 hours, suction filtration was performed using glass fiber F paper GC-90, water was added to the filtrate, and the entire volume was io
o at.

The results of analyzing the components of this liquid + 000 mt were analyzed in the fourth section.
Shown in the table.

(1i) Mibuki Nari 15o9 shown in Table 5, No. 2 above (1
) was added to a caustic soda solution under the same conditions as above, water was added to make the total volume 900 at, and 1 g of sodium gluconate was added to this to facilitate washing of a large amount of floating matter suspended in the solution. Organic flocculant (Himoloku 5S-120)
+Oppm was added, and after leaving for 2 hours, the above (1
) in the same manner as above, add water to solution F, and reduce the total volume to 1
000 votes.

Table 4 shows the results of analyzing the components of this citrus liquid + o o o mt.

Table 4 Experiment 2 Furnace liquid (sodium aluminate liquid) obtained in Experiment 1 (1)
For 100011L/, 517g% of JI8 No. 5 sodium silicate was obtained in (11) of Experiment 1, and for 1000" of the dried aluminate solution (sodium aluminate solution), TIS
No. 5 sodium silicate 5149 was added and the zeolite synthesis reaction was carried out for 6 to 7 hours with strong stirring according to a known method). After the reaction, a glass fiber furnace cloth GC-90 was used to synthesize the zeolite. /), and the zeolite remaining on the furnace cloth was washed with about s o vat of water and dried in a drying oven at 100° C. for 12 hours.

The yield and performance of each zeolite thus obtained were examined, and at the same time the components of each p-liquid collected were analyzed. The results were as shown in Table 5.

Table 5 (Note 13 Aluminum 2A/
.

The percentage of the actual yield relative to the theoretical amount of zeolite calculated from In other words, the amount calculated by 4.

(Note 2) Calcium adsorbed by 1g of zeolite is CaC
O5 conversion ■ Equivalent value This experiment 6 Experiment IC) From the reaction equation (4) shown in (1), theoretically from the Mitsuki 100'9 shown in floor 1 of Table 3, at room temperature and normal pressure. You should get OH1.

Therefore, using the experimental equipment shown in Figure 1, we performed H
2 gases were recovered.

After pouring 1,000 ml of the ml shown in Table 5 into a glass bottle 1, add 50 ml of caustic soda solution with a concentration of 2509/ml.
℃, then quickly close the mouth with a rubber stopper 2 with a glass tube, guide the generated gas through the rubber tube 5, and pour it into the water basin 4.
A measuring cylinder 5 having an IL capacity was filled with water and introduced into the cylinder which was turned upside down.

The amount of gas thus recovered was 5401 n1.

In addition, this recovered gas contains H, 99.5%, OH, 0.1%
, there was residual air.

Experiment 4 (Using 150g of Mibukisei shown in column 1 of Table 6, 2
Sodium aluminate solution was prepared in exactly the same manner as in (1) of Experiment 1, except that 509 Zta degree caustic soda solution was used and 0.19% of sodium gluconate was added to Solution F. 1 g of aluminum hydroxide cL was added to this liquid as a seed crystal, and the mixture was stirred using a magnetic stirrer for about 4 days.

The precipitated aluminum hydroxide was filtered using f) C-90, and the aluminum hydroxide on the door cloth was washed with so many tons of pure water, and then dried in a drying oven at 100°C for 12 hours.

At the same time, the yield and purity of the aluminum hydroxide P obtained in this manner were verified, and the above solution was adjusted to 10 o o rat again and the components were analyzed. are shown in Table 6 together with the component values of the stock solution before addition of the seed crystals.

(It) Aluminum hydroxide was produced under the same conditions as in (1) above, except that 200 g of Mibukise shown in Kan 2 in Table 6 was used, and the same tests and analyzes as in (1) above were performed. The results are shown in Table 6.

Table 6

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the experimental apparatus used in the gas recovery experiment of the present invention. Agents 1) Akira Agent Ryo Hagiwara - Procedural Amendments Director of the Japan Patent Office Kazuo Wakasugi1, Indication of the case Patent Application No. 137458 of 19822, Name of the invention Method of utilizing aluminum ash3, Person making the amendment Relationship to the case Patent applicant 4, agent (and 1 other person) Contents of the amendment in column a of the “detailed description of the invention” of the specification (1) Changed “poetic sentiment” on page 4, line 13 of the specification to “actual circumstances” correct. (2) (3) in the second bottom line of Table 5 on page 14 of the same page After "was." These are the results of analysis using gas chromatography. jKiriniri Zuzu

Claims (3)

[Claims] (1) Aluminum ash is dissolved in a 10-50% caustic soda solution to produce sodium aluminate, and then sodium silicate is added to the sodium silicate solution to produce synthetic zeolite. A method of utilizing aluminum ash, which is characterized by recovering gas generated during the production of acid soda. (2) Dissolve aluminum ash in 10 to 50 grams of caustic soda solution to produce sodium aluminate, then dilute the sodium aluminate solution with water, add seed crystals, and precipitate aluminum elate. A method for utilizing aluminum ash, characterized in that, at the same time, the gas generated during the production of the sodium aluminate is recovered. (3) Claim (1) characterized in that during the production of sodium aluminate, one or more of gluconic acid or an alkali salt thereof, tartaric acid or an alkali salt thereof, triethanolamine, or sorbitol is added; (
2) The method described.