JP7527651B2 - Deodorant and its manufacturing method - Google Patents

Description

The present invention relates to a deodorant using aluminum dross as a raw material and a manufacturing method thereof, and in particular to a deodorant with high hydrogen sulfide adsorption capacity that uses aluminum dross as a deodorant carrier and a manufacturing method thereof.

When aluminum products or materials are melted in order to be recycled, the molten aluminum reacts with the air to produce oxides and nitrides. This by-product containing oxides is called aluminum dross, and most of it has been effectively used as secondary materials in steel manufacturing. However, in recent years, water and soil pollution caused by the elution of fluorine and other substances from steel slag has led some companies to stop using aluminum dross. One of the reasons why it contains components such as fluorine that are unsuitable for use in steel slag is that flux agents containing fluorine and chlorine are added during the melting process to increase the recovery rate and purity of metallic aluminum.

In this context, the amount of aluminum dross that is not effectively used as a secondary material in steel manufacturing is increasing, and most of it is disposed of in landfills as industrial waste. However, when aluminum dross is disposed of in landfills, there is a risk that hydrogen will be generated by the reaction between aluminum and water, ammonia will be generated by the reaction between aluminum nitride and water, salt damage will occur due to chlorides, and environmental pollution will occur due to fluorides. For this reason, there has been a demand for the development of new uses for aluminum dross.

Aluminum dross contains halogens, so it is desirable to remove the halogens if it is to be used effectively. A method of wet treating aluminum dross is known as a method of removing halogens, and Patent Document 1 discloses a method of oxidizing ammonia generated during wet treatment with ozone. Patent Document 1 also proposes uses for treated aluminum dross other than the steelmaking process, such as raw materials for various ceramic products such as building materials.

JP 2020-142190 A

Therefore, the present invention aims to provide a new use for aluminum dross.

The inventors of the present invention conducted extensive research to find new uses for aluminum dross, and discovered that a deodorant with excellent deodorizing performance could be obtained by stirring the aluminum dross in water, separating the solids, and firing the mixture. As a result of further research, the inventors discovered that a deodorant with excellent hydrogen sulfide adsorption performance and significantly improved deodorizing performance could be obtained by stirring the aluminum dross in water, separating the solids, drying the mixture, adding ferric sulfate, hydrated lime, and water, mixing the mixture, drying, and firing the mixture, and thus arrived at the present invention.

That is, the method for producing the deodorant of the present invention is characterized by stirring aluminum dross in water, separating the solids, adding ferric sulfate, hydrated lime, and water to the solids, mixing, and calcining the mixture.

Another feature of this method is that ozone is supplied to the water when the aluminum dross is stirred in the water.

The method is also characterized by stirring aluminum dross with added calcium carbonate in water.

Furthermore, after adding and mixing ferric sulfate, hydrated lime, and water, the mixture is dried and then fired without curing or filtering.

The deodorant of the present invention is characterized in that it is obtained by the method for producing a deodorant of the present invention.

The catalyst is also characterized in that the static hydrogen sulfide adsorption capacity 120 hours after the start of adsorption is 100 (gH ₂ S)/(100 g sample) or more.

It is also characterized by having a pH of 10 or higher.

The deodorant and manufacturing method of the present invention can provide a deodorant with excellent deodorant performance by using aluminum dross as a raw material.

FIG. 1 is an X-ray diffraction diagram of calcium carbonate used in an embodiment of the present invention.

The method for producing the deodorant of the present invention involves stirring aluminum dross in water, separating the solids, adding ferric sulfate, hydrated lime, and water, mixing, and calcining the mixture.

[Aluminum dross]
Aluminum dross is a by-product produced when aluminum is melted during the recycling process of aluminum products, and includes oxides such as aluminum oxide, nitrides such as aluminum nitride, as well as metallic aluminum and halogens.

The composition of the aluminum dross used in the present invention is not limited to a specific composition, and aluminum dross of various compositions can be used in the present invention, and any component in the aluminum dross may be adjusted. In addition, the form of the aluminum dross used in the present invention is not limited to a specific form, but it is preferably a powder in terms of its high reactivity with water.

Furthermore, aluminum dross containing metallic aluminum powder may ignite. For this reason, calcium carbonate may be added to aluminum dross as a non-flammable powder for safety reasons. In the present invention, aluminum dross to which such calcium carbonate has been added can also be used.

Each step in the manufacturing method of the deodorant of the present invention will be described below.

[Mixing process]
First, the aluminum dross is stirred in water. When the aluminum dross is stirred in water, the metallic aluminum contained in the aluminum dross reacts with the water to produce aluminum hydroxide and hydrogen, and the aluminum nitride reacts with the water to produce aluminum hydroxide and ammonia. The conditions for the hydration reaction treatment in this stirring process, such as the mixing ratio of the aluminum dross to the water, the temperature, and the stirring time, are not limited to specific conditions, but are preferably set so that the reaction between the aluminum nitride contained in the aluminum dross and the water proceeds efficiently. In addition, the stirring process is preferably performed until the generation of ammonia substantially stops.

Although the stirring method is not limited to a specific method, stirring by bubbling air into the water allows stirring and air supply to be performed simultaneously, which promotes the hydration reaction and also efficiently removes the hydrogen and ammonia produced by the hydration reaction from the water. When bubbling air, fine bubbles are preferable to further promote the hydration reaction.

In addition, if ozone is supplied to the water when the aluminum dross is stirred in the water, the generated ammonia reacts with the ozone to produce nitric acid, water, and oxygen, preventing the release of ammonia into the atmosphere. Therefore, in order to prevent the generation of foul odors during the manufacturing process, ozone may be supplied to the water in the stirring process. The conditions for the ozone supply method and supply amount in this hydration reaction treatment using ozone water are not limited to specific conditions, but it is preferable to set them so as to prevent the release of ammonia into the atmosphere. In addition, when bubbling is used for stirring, ozone may be supplied together with the air that is bubbled into the water.

[Separation process]
After the stirring step is completed, the solid content is separated. This separation step can be performed by a known method such as filtration. The obtained solid content is a chemically stable composition in which aluminum hydroxide is the main component, and aluminum metal, aluminum nitride, and halogens are removed from the raw aluminum dross by the hydration reaction treatment. After the separation step, the solid content may be dried, or may be transferred to the next mixing step without drying.

[Mixing process]
After the separation step is completed, ferric sulfate, slaked lime, and water are added to the separated solids and mixed. At this time, ferric sulfate is added in an amount of 5 to 20 parts by weight as Fe ₂ O ₃ , and slaked lime is added in an amount such that the atomic ratio of Ca/Fe is 2 to 5, relative to 100 parts by weight of the separated solids (corresponding to the dried product obtained by drying at 110° C.), thereby making it possible to make the pH of the deodorant obtained by the deodorant manufacturing method of the present invention 10 or more. The amount of water added is preferably 80 to 100 parts by weight. The amount of water added may be adjusted according to the amount of moisture already contained in the solids.

After that, no curing or filtering steps are required before the next firing step. This allows the deodorant of the present invention to be produced efficiently and without wasting time. In addition, because no filtering step is required, the added ingredients can be used effectively.

[Firing process]
After the mixing step is completed, the mixture is calcined. The aluminum hydroxide after the mixing step has a small specific surface area due to remaining adhering water and crystallization water, and does not function as a deodorant in this state. Therefore, in this calcination step, an appropriate heat treatment is performed to remove the adhering water and crystallization water and increase the specific surface area. The conditions of the heat treatment in this calcination step, such as temperature and time, are not limited to specific conditions, but are preferably set so that the specific surface area after heat treatment is large. The mixture is preferably calcined at a temperature of 300 to 400°C. It is preferable to dry the mixture before the calcination step, but drying can be omitted if molding is not required.

Here, if the heat treatment temperature is less than 300°C, the adhering water and crystal water may not be completely removed from the aluminum hydroxide, and the specific surface area of the aluminum hydroxide after heat treatment may not be increased. On the other hand, if the heat treatment temperature exceeds 400°C, the water is removed from the aluminum hydroxide and it is converted to aluminum oxide. If it is completely converted to aluminum oxide, the specific surface area decreases, which reduces its function as a deodorant, and this is not preferable.

When molding, the mixture is dried after the mixing process is completed, and then the particle size is adjusted by grinding if necessary. An organic binder or an inorganic binder is added to the resulting dry powder, and after adjusting the moisture content, the mixture is molded by normal extrusion molding, rolling granulation, etc. After that, it is dried and fired to produce the deodorant as a molded product.

[Deodorants]
The deodorant obtained by the method for producing a deodorant of the present invention has extremely high hydrogen sulfide adsorption performance, and has a static hydrogen sulfide adsorption capacity of 100 (gH ₂ S/100 g sample) or more 120 hours after the start of adsorption.

It is also preferable that the deodorant obtained by the method for producing a deodorant of the present invention has a pH of 10 or more.

By maintaining a pH of 10 or higher, the sulfate radicals contained in the deodorant are fixed as insoluble sulfate salts and are not detected as soluble gypsum. Specifically, the sulfate radicals are insoluble by being fixed in the crystal structure of aluminum-iron ettringite. As a result, it is believed that the sulfate radicals do not adversely affect the deodorant ability.

When sulfate radicals exist as soluble gypsum, moisture is produced during deodorization, and the sulfate radicals dissolved in the moisture reduce the deodorizing ability of the iron ions. Sulfate radicals dissolved in water have a so-called poisoning effect.

However, the crystal structure of aluminum-iron ettringite can be confirmed at temperatures below 50°C because water of crystallization remains, but at temperatures above 300°C, the water of crystallization disappears and the material becomes amorphous, making it impossible to confirm the crystal structure. When the deodorant obtained by the manufacturing method of the present invention was immersed in water to cause a hydration reaction and then dried at 50°C, the crystal structure of aluminum-iron ettringite could be confirmed. This suggested that the crystal structure of aluminum-iron ettringite remains in the deodorant obtained by the manufacturing method of the present invention.

As described above, the deodorant obtained by the method for producing a deodorant of the present invention has extremely excellent deodorizing performance. Therefore, according to the deodorant and its production method of the present invention, it is possible to provide a deodorant with excellent deodorizing performance by using aluminum dross as a raw material.

The following is a detailed description of the embodiments of the deodorant and its manufacturing method of the present invention. Note that the present invention is not limited to the following embodiments, and various modifications are possible.

[Sample preparation]
(1) Preparation of a sample (sample A) subjected to a hydration reaction treatment 45 g of aluminum dross powder obtained from an aluminum manufacturer was dispersed in 450 mL of pure water, and air was bubbled at a flow rate of 0.5 L/min for 48 hours at 50° C. Then, the solid content was separated by filtration and dried at 110° C. The powder thus obtained was calcined at 400° C. for 2 hours to obtain sample A.

(2) Preparation of sample (sample B) subjected to hydration reaction treatment and ozone water treatment 45 g of aluminum dross powder obtained from an aluminum manufacturer was dispersed in 450 mL of pure water and stirred at 50° C. for 48 hours by bubbling air at a flow rate of 0.5 L/min. Then, the mixture was stirred at 50° C. for 24 hours while supplying ozone at a rate of 2 g/hour into the water via bubbling air at a flow rate of 0.5 L/min. Then, the solid content was separated by filtration and dried at 110° C. The powder thus obtained was used as carrier B. Then, carrier B was calcined at 400° C. for 2 hours to obtain sample B.

(3) Preparation of a sample (sample C) subjected to hydration reaction treatment after addition of calcium carbonate 45 g of aluminum dross powder obtained from an aluminum manufacturer and 9.0 g of calcium carbonate were dispersed in 450 mL of pure water, and air was bubbled at a flow rate of 0.5 L/min for 48 hours at 50°C. The solid content was then separated by filtration and dried at 110°C. The powder thus obtained was designated as carrier C. Then, carrier C was calcined at 400°C for 2 hours to obtain sample C.

(4) Preparation of a sample (sample D) in which ferric sulfate was added to carrier C 6.74 g of polyferric sulfate and 7.8 g of water were added as ferric sulfate components to 20 g of carrier C, and mixed for 5 minutes. Then, 2.0 g of slaked lime and 8.0 g of water were added, and mixed for 5 minutes. After 1 hour, the mixture was dried at 50°C for 6 hours without filtration, and then dried at 110°C for 2 hours. The powder thus obtained was calcined at 400°C for 1 hour to obtain sample D.

(5) Preparation of a sample (sample E) in which ferric sulfate was added to carrier B 6.74 g of polyferric sulfate and 7.8 g of water were added as ferric sulfate components to 20 g of carrier B, and mixed for 5 minutes. Then, 4.5 g of slaked lime and 8.0 g of water were added, and mixed for 5 minutes. After 1 hour, the mixture was dried at 50°C for 6 hours without filtration, and then dried at 110°C for 2 hours. The powder thus obtained was calcined at 400°C for 1 hour to obtain sample E.

[Testing and Analysis]
(1) Hydrogen sulfide static adsorption test 0.20 or 0.5 g of powder sample was placed in a 10 or 20 L Tedra bag, and 10 or 20 L of hydrogen sulfide with a concentration of 1% by volume was poured into the Tedra bag, and the test was started. 100 mL of gas was sampled from the Tedra bag at 6 hours, 24 hours, 48 hours, 72 hours, 120 hours, and 168 hours after the start of the test, and the remaining concentration of hydrogen sulfide was measured using a hydrogen sulfide detector tube manufactured by Gastec Corporation. The results are shown in Table 1.

The static hydrogen sulfide adsorption capacity was then calculated from the initial concentration and the residual concentration. The results are shown in Table 2.

From the values of the hydrogen sulfide static adsorption capacity shown in Table 2, it was confirmed that in samples D and E, the hydrogen sulfide static adsorption capacity 120 hours after the start of adsorption was 100 (g-H ₂ S/100 g sample) or more, and samples D and E had higher hydrogen sulfide adsorption performance than samples A to C.

In other words, aluminum dross was stirred in water, the solids were separated, dried, and sintered (A-C), but aluminum dross was stirred in water, the solids were separated, and then ferric sulfate, hydrated lime, and water were added, mixed, and sintered (D, E) and showed higher hydrogen sulfide adsorption performance.

(2) pH Measurement The measurement was carried out in accordance with JGS 0211-2000. That is, a sample in a natural water content state adjusted to a particle size of 10 mm or less was placed in a beaker, water was added so that the mass ratio of water (including the water in the sample) to the dry mass of the sample was 5, and the mixture was stirred and left to stand for 1 hour to prepare a sample solution. The pH of this sample solution was then measured. The results are shown in Table 1.

The pH values shown in Table 1 show that samples A to C had a pH of less than 10, while samples D and E had a pH of 10 or higher.

(3) Quantitative Analysis Quantitative analysis was carried out based on JIS M8853:1998, which is defined as a method for chemical analysis of aluminosilicate raw materials for ceramics. The results are shown in Table 3.

The ignition loss values shown in Table 3 indicate that all samples A to C had an ignition loss of 20% or more. A large ignition loss indicates a large number of hydroxyl groups. Furthermore, the greater the number of hydroxyl groups, the higher the adsorption performance of the deodorant can be expected.

[material]
The above experiments were carried out using the following materials:

(1) Calcium carbonate: Grade 1 reagent (Cica) manufactured by Kanto Chemical Co., Ltd. was used.

The results of qualitative analysis performed using a Rigaku Corporation ZSX Primus II X-ray fluorescence analyzer are shown in Table 4.

Figure 1 shows the results of measurements taken using the Rigaku Corporation RINT-Ultima III X-ray diffraction device.

(2) Calcium hydroxide (slaked lime)
The reagent (Cica) grade 1 manufactured by Kanto Chemical Co., Ltd. was used.

(3) Polyferric sulfate As the ferric sulfate component, polyferric sulfate manufactured by Nittetsu Mining Co., Ltd. was used. The properties are shown in Table 5.

Claims (4)

A method for producing a deodorant, characterized by stirring aluminum dross in water, separating the solids, adding ferric sulfate, hydrated lime, and water, mixing, and firing. The method for producing the deodorant described in claim 1 is characterized in that ozone is supplied to the water when the aluminum dross is stirred in the water. The method for producing the deodorant according to claim 1 or 2, characterized in that aluminum dross to which calcium carbonate has been added is stirred in water. The method for producing a deodorant according to any one of claims 1 to 3, characterized in that after adding and mixing ferric sulfate, hydrated lime, and water, the mixture is dried and then calcined without curing or filtering.