Methods for sorting and reusing secondary aluminium dross

Abstract

The solid, liquid, and gaseous substances generated during the processing of secondary aluminum dross are reused. [Solution] The present invention comprises a reaction process which includes a process for classifying secondary aluminum dross, a process for deoxidizing the inside of a processing vessel, a process for stirring, mixing and reacting the secondary aluminum dross with water in the processing vessel, and a process for cooling or maintaining the temperature inside the processing vessel during the reaction; a gas-liquid phase process which includes obtaining hydrogen and a plurality of compounds from the gas-liquid phase of the slurry of secondary aluminum dross and water after the reaction process; and a solid phase process which includes obtaining an industrial solid phase material from the solid phase of the slurry of secondary aluminum dross of a predetermined particle size and water after the reaction process, wherein the liquid phase used or generated in the gas-liquid phase process and the solid phase process is rendered harmless and reused in each of the above processes. [Effect] Almost the entire amount of secondary aluminum dross and water used in the treatment can be reused without waste.

Description

[Technical Field]

[0001] The present invention relates to a method for separating and reusing secondary aluminum dross, making it reusable in each of the solid, liquid, and gaseous phases generated during the processing of secondary aluminum dross. [Background technology]

[0002] Aluminum production processes generate a residue called aluminum dross (aluminum ash), and it is said that tens of thousands of tons of this aluminum dross are generated annually in Japan. The biggest problem with aluminum dross disposal is that if left unattended (stored) or during processing, the aluminum nitride, metallic aluminum, and water it contains react, generating heat, ammonia, and hydrogen, which can cause fires, explosions, foul odors, and health problems.

[0003] Therefore, numerous methods for treating aluminum dross, which had not been established before, have been proposed, and these can be broadly classified into dry treatment and wet treatment. Dry treatment is a method in which the residual ash is heated to a high temperature of 1000°C or more in a rotary kiln or the like, and the constituent phases can be converted into oxides by combustion oxidation, which can be used as oxide raw materials, but it has the problem of high energy consumption and high cost. On the other hand, the wet treatment proposed in this application is a method in which aluminum dross is reacted with water, and is more cost-effective than the dry treatment method, but it is accompanied by the generation of ammonia, so the removal of the discharged ammonia has been a problem.

[0004] The main composition and mass fraction of aluminum dross is 10-30% metallic aluminum, 20-40% alumina, 7-15% silicon, magnesium, and iron oxides, and 15-30% potassium, sodium, calcium, magnesium chlorides, and other trace amounts of fluorides.

[0005] Aluminum dross is classified into primary aluminum dross and secondary aluminum dross, depending on the number of times metallic aluminum or aluminum alloys are recovered in the recycling process and their content.

[0006] Primary alumina dross is an insoluble slag produced in the process of producing metallic aluminum using electrolytic alumina. The metallic aluminum content in primary alumina dross is 30-85%, and it also contains other substances such as fluorides, alumina, and aluminum nitride.

[0007] Secondary aluminum dross is waste slag produced in the remelting process of primary aluminum dross or in the process of recovering metallic aluminum from spruced aluminum. The metallic aluminum content in secondary aluminum dross is 5-20%, and it also contains alumina, aluminum nitride, chloride compounds such as fluorine, and silicon dioxide.

[0008] The dangers of processing secondary aluminum dross are that, as mentioned above, the secondary aluminum dross reacts with water or moisture during wet processing to generate a gas phase of toxic, harmful, flammable, and malodorous gases such as ammonia (H3), methane (CH4), phosphine (PH3), hydrogen (H2), and hydrogen sulfide (H2S), and simultaneously, various heavy metals are present in the secondary aluminum dross (solid phase) after the gas phase has been generated.

[0009] Conventionally, the following Patent Documents 1 to 3 all propose a process for detoxifying and reusing aluminum dross through wet processing. For example, Patent Document 1 (Japanese Patent No. 7249075) describes a method for obtaining concrete material through the following steps: a process of pulverizing secondary aluminum dross, which is the residue of primary aluminum dross for recovering metallic aluminum or aluminum alloy in aluminum dross; a process of polishing the particles of secondary aluminum dross into a spherical shape; a process of deoxidizing by replacing the air in a container containing the spherical powdered secondary aluminum dross with nitrogen gas for reaction with water; a process of continuing the deoxidization process for a predetermined time to maintain the deoxidized state while mixing and reacting the water with the spherical powdered secondary aluminum dross; a process of separating and collecting the compounds produced by the reaction; and a process of repeatedly stirring and washing with water and separating the solid-liquid mixture obtained from the separate collection process.

[0010] Furthermore, Patent Document 2 (Japanese Patent No. 7249076) describes a method for safely producing hydrogen through the following steps: a process of crushing secondary aluminum dross into a powder; a process of polishing the particles of secondary aluminum dross into a spherical shape; a process of deoxidizing the spherical powdered secondary aluminum dross by replacing the air in a container for reacting it with water with nitrogen gas; a process of continuing the deoxidation process for a predetermined time to maintain the deoxidized state while mixing water and the spherical powdered secondary aluminum dross, wherein the process is divided into a reaction stage that generates heat, followed by a reaction stage that requires heat using the heat generated in the previous stage; a process of collecting the gases generated in each of these stages; and a process of extracting hydrogen from the collected gases.

[0011] Furthermore, Patent Document 3 (Japanese Patent No. 7252683) describes a process for pulverizing secondary aluminum dross, polishing the pulverized particles of secondary aluminum dross, deoxidizing the polished particulate secondary aluminum dross by replacing the air in a container for reacting it with water with nitrogen gas, and continuing the deoxidizing process for a predetermined time to maintain the deoxidized state while mixing and reacting the water and secondary aluminum dross. The process of mixing and reacting the water and secondary aluminum dross is shown to detoxify the secondary aluminum dross by performing, in this order, a first fractionation process to react with aluminum nitride, a second fractionation process to react with metallic aluminum, and a third fractionation process to react with gas-generating components remaining in the secondary aluminum dross to separate the gas phase and solid-liquid phase.

[0012] However, conventional technologies, including the aforementioned Patent Documents 1 to 3, have been limited to detoxifying the solid phase through washing and extracting hydrogen from the gas phase, and have not considered the detoxification and reuse of the substances produced in these processes.

[0013] In particular, regarding the water used in wet treatment, the water used for washing to detoxify the solid phase, and the reaction water used to react with hydrogen, no consideration was given to detoxifying the water used in each treatment process when they were recycled or discharged. [Prior art documents]

Patent Document

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0015] The problem to be solved is that conventionally, there has been no consideration regarding the detoxification and reuse of almost all substances generated or used in the wet treatment of secondary aluminum dross.

Means for Solving the Problems

[0016] To solve the above problems, the present invention provides a method for separately reusing secondary aluminum dross for detoxifying secondary aluminum dross, which is the residue of primary aluminum dross for recovering metallic aluminum or aluminum alloy in aluminum dross, and for detoxifying and reusing substances generated and used in this detoxification treatment. The method includes a reaction treatment step of classifying the solid phase of secondary aluminum dross into a predetermined particle size, replacing the inside of a treatment kettle where secondary aluminum dross of a predetermined particle size and water are mixed and reacted with nitrogen for deoxidation, charging the treatment kettle with secondary aluminum dross of a predetermined particle size and water, and stirring, mixing, and reacting them, and cooling or maintaining the temperature according to the temperature inside the treatment kettle during the reaction; a gas-liquid phase treatment step of obtaining hydrogen and a plurality of compounds from the gas-liquid phase of a slurry of secondary aluminum dross of a predetermined particle size and water after the reaction treatment step; and a solid phase treatment step of obtaining an industrial solid phase material obtained by detoxifying the solid phase from the solid phase of a slurry of secondary aluminum dross of a predetermined particle size and water after the reaction treatment step. Further, the liquid phase used or generated in the gas-liquid phase treatment step and the solid phase treatment step is detoxified and reused in the reaction treatment step, the gas-liquid phase treatment step, and the solid phase treatment step.

Effects of the Invention

[0017] The present invention can detoxify secondary aluminum dross by wet treatment, and can detoxify substances used in the detoxification treatment of secondary aluminum dross or substances generated during the detoxification treatment of secondary aluminum dross. Therefore, there is an advantage that almost all of it can be disposed of as general waste or reused as an industrial raw material. In particular, the water or liquid phase used in the detoxification treatment of secondary aluminum dross can be reused in the detoxification treatment and can be drained if unnecessary.

Brief Description of Drawings

[0018] [Figure 1] It is a flowchart showing the schematic process in the method of the present invention and the reaction process between secondary aluminum dross and water. [Figure 2] It is a flowchart showing the gas-liquid phase treatment process in the method of the present invention. [Figure 3] It is a flowchart showing the outline of the solid phase treatment process in the method of the present invention. [Figure 4] It is a flowchart showing the first washing treatment of the solid phase treatment process in the method of the present invention. [Figure 5] It is a flowchart showing the second washing treatment of the solid phase treatment process in the method of the present invention. [Figure 6] It is a flowchart showing the third washing treatment of the solid phase treatment process in the method of the present invention. [Figure 7] It is a flowchart showing the washing water treatment (1), (2), and (3) of the solid phase treatment process in the method of the present invention. [Figure 8] It is a diagram showing the schematic configuration of the treatment kettle used in the method of the present invention.

Modes for Carrying Out the Invention

[0019] The treatment method of the present invention will be described here with reference to FIGS. 1 - 8. FIG. 1 is a flowchart for explaining the whole. FIGS. 2 - 7 show subroutines for the gas phase treatment and solid phase treatment in FIG. 1, and FIG. 8 shows the treatment kettle used in the treatment method of the present invention. These drawings will also be referred to in the examples described later.

[0020] As shown in Figure 1, in this invention, from the start of the process to the end of the process, harmless general chemical raw materials, hydrogen, and general solid-phase raw materials are obtained, with harmful factors of secondary aluminodros eliminated, and the water used in the process is detoxified and recycled or discharged.

[0021] (Processing pot): Figure 8 Many of the processes of the present invention are carried out in the processing vessel shown in Figure 8. Multiple processing vessels are provided depending on the process and processing sequence. The processing vessel is equipped with an inlet 1, a water intake 2, a vessel body 3, an ultrasonic stirrer 4, a stirring blade 5, a discharge valve 6, a slurry pump 7, a liquid level gauge 8, a speed reducer 9, a motor 10, an annular pneumatic supply pipe 11, a supply pipe 12, and a water-cooled heating jacket 13.

[0022] The ultrasonic stirrer 4 is used to generate vibrations and vortices in the slurry within the vessel 3 in order to improve stirring efficiency. The ultrasonic stirrer 4 is controlled to generate ultrasonic waves in the range of 20-80 kHz for vibrations, and optimally in the range of 30-50 kHz. The ultrasonic stirrer 4 is also controlled to generate vortices in the opposite direction to the rotation of the stirring blades 5.

[0023] The stirring blade 5 is controlled to a rotation speed in the range of 20-80 r / min, and optimally controlled to 40-60 r / min. The annular pneumatic pipe 11 is located at the inner bottom of the kettle body 3, is made of porous ceramics, and ejects carbon dioxide supplied from the pneumatic pipe 12.

[0024] -Reaction process between secondary aluminum dross and water: Figure 1- (Classification process) The primary aluminum dross and the separated secondary aluminum dross are stored in a sealed, moisture-proof container. The humidity inside this container is kept as low as possible. Next, the secondary aluminum dross removed from the moisture-proof container is sorted by particle size of 125 μm using a powder separator. Secondary aluminum dross with a particle size exceeding 125 μm is sent for further processing or returned to the moisture-proof container. On the other hand, secondary aluminum dross with a particle size of 125 μm or less is subjected to the next reaction with water.

[0025] Here, by using secondary aluminum dross with a particle size of 125 μm or less in the subsequent processing, the reaction rate with water is significantly improved, and the content of metallic aluminum and aluminum nitride in the residue after reaction with water is reduced, that is, the amount of unreacted material can be reduced. In this invention, it is desirable that the particle size is largely contained in the range of 1 to 25 μm, but in order to shorten the overall processing time, crushing and polishing are not included in the processing in this invention in order to achieve a particle size of 1 to 25 μm.

[0026] (Deacidification treatment) Next, the air (oxygen) inside the processing vessel is replaced with nitrogen. This process of replacing the air (oxygen) inside the processing vessel with nitrogen, i.e., deoxidization, reduces the risk of ignition and explosion during hydrogen extraction in the liquid phase treatment.

[0027] (Reaction process) The secondary aluminum dross with a particle size of less than 125 μm after classification is finally introduced into the processing vessel in a solid-liquid ratio (mass ratio) of 1:2-10, preferably 1:3-6. The order in which water and secondary aluminum dross should be added to the processing vessel is as follows: instead of adding all the water at once, approximately one-third of the total amount of water should be added first. The water introduced here may be fresh water, but in this invention, the detoxified treated water produced in the liquid phase treatment described later and the detoxified treated water produced in the solid phase treatment described later are reused in a cyclical manner.

[0028] Next, the secondary aluminum dross is added to the processing vessel, and at the same time, the remaining two-thirds of the total amount of water is added and stirred for a predetermined time. At the start of stirring, appropriate amounts of calcium hydroxide and catalyst are also added to the vessel. The conditions for the processing vessel are as follows: pressure inside the vessel is atmospheric pressure, and temperature is 5-99°C, preferably 80-90°C. The reaction time (stirring time) under these conditions is 5 hours to 48 hours. The above reaction time is defined as the time it takes for the metallic aluminum and the aluminum nitride in the secondary aluminum dross to react almost completely. The reaction (stirring) is considered complete when the clinker content of metallic aluminum and aluminum nitride in the reaction residue is found to be below a predetermined amount.

[0029] The amount of calcium hydroxide added at the start of stirring is 1-10% of the amount of secondary aluminum dross, preferably so that even when supersaturated, the pH of the stirred liquid phase (slurry) remains at 12-13. The catalyst added at the start of stirring shall be in an amount of 1-10%, more preferably 3-8%, of the mass of the secondary aluminosate. The catalyst shall consist of one or more of the following substances in their respective compositional (mass) proportions: sodium carbonate (1-10%), potassium carbonate (1-10%), sodium hydroxide (10-80%), potassium hydroxide (5-50%), carbide slag (10-30%), and sodium stannate (0.01-5%).

[0030] The reaction between secondary aluminum dross and water can be divided into three phases: induction, acceleration, and deceleration. During the "induction period," or approximately 0.5-1 hour after the start of the hydrolysis reaction, the reaction rate is slow and no significant exothermic reaction is observed. The "acceleration phase" occurs approximately 0.5-1 hours after the start of the hydrolysis reaction, when the reaction rate accelerates and is accompanied by significant exothermic activity. During the "deceleration phase," the reaction rate and heat generation rate slow down, and gradually heat generation ceases (the temperature inside the furnace decreases).

[0031] During the acceleration phase described above, the temperature inside the processing vessel exceeds the boiling point of water (100°C). When steam is generated inside the processing vessel, the internal pressure increases, making reaction control complex and difficult, and also making hydrogen production in the subsequent gas-liquid treatment process difficult. For this reason, the temperature inside the processing vessel is controlled not to exceed 100°C during the "induction phase" and the "acceleration phase." In this example, specifically, the temperature is adjusted by passing water through a water-cooled jacket 13 arranged around the outer circumference of the processing vessel. Since the water passed through the water-cooled jacket 13 is simply circulated and exchanged between the water-cooled jackets 13 of multiple processing vessels, fresh water (hereinafter referred to as "fresh water") is used in this example.

[0032] In this example, once the reaction temperature in the processing vessel rises to 70-90°C during the initial induction-acceleration phase, fresh water is passed through the water-cooled jacket 13, and the flow rate is controlled so that the rate of increase in the temperature inside the processing vessel is 0.1-3°C / min.

[0033] When the fresh water passes through the water-cooled jacket 13, if it is circulated, it is cooled by absorbing heat from the temperature inside the boiler, and the heated water is sent to another water-cooled jacket 13, for example, another boiler that has been processing earlier and has entered a slowdown phase, for use in maintaining its temperature. Of course, since it is fresh water, it can also be used as top-up water for the reaction described later. However, when it is circulated as in this example, it has the advantage of reducing the amount of fresh water that needs to be added, thereby lowering treatment costs. Furthermore, by using the water-cooled heating jacket 13, it is possible not only to prevent the temperature from exceeding 100°C, but also to suppress unnecessary temperature drops that hinder reaction promotion during the deceleration phase.

[0034] During the deceleration phase described above, when the heating rate stops, meaning the temperature inside the processing vessel stabilizes at a constant level, for example, in the range of approximately 80-90°C, the following control is performed to maintain this stable state for a certain period of time. For example, the temperature that remains constant within the range of 80-90°C during the measurement period is recorded as T1. Subsequently, once the temperature begins to decrease from T1 (a constant temperature), the cooling water heated during the acceleration phase is used as retaining water. The temperature of this retaining water is recorded as T2. When T2 > T1, the temperature difference between the two is set to 1-10°C. Then, the flow rate of the heat-retaining water flowing through the water-cooled jacket 13 is adjusted so that the temperature inside the processing vessel is maintained at 80-90°C during the deceleration phase.

[0035] After the above steps, the slurry, having completed its reaction with water, is separated into a gas-liquid phase and a solid phase. The gas-liquid phase is transferred to another processing vessel for the treatment shown in Figure 2, and the solid phase is transferred to another processing vessel for the treatment shown in Figures 3-7. The slurry is moved through pipes connecting the processing vessels to prevent it from being exposed to the outside air between them. After the reaction treatment of secondary aluminum dross with water is complete, the slurry is transferred to each treatment vessel, and after an interval of 1-2 hours, the water and secondary aluminum dross for the reaction are added again to perform the above procedure.

[0036] -Gas-liquid phase treatment process: Figure 2- (Summary) In the gas-liquid phase treatment process, the gas generated during the reaction treatment of the secondary aluminum dross with water, and the exhaust gas during deoxidation (exhaust) for 1 to 30 minutes, preferably 3 to 8 minutes, after the stirring of the reaction treatment is completed are collected. From the collected gas, hydrogen that meets the fuel hydrogen standard with a purity (mass fraction) of 99% or more is mainly obtained, and from the slurry obtained, compounds that are common industrial raw materials such as aluminum hydroxide, sodium bicarbonate, sodium sulfate, sodium chloride, ammonium chloride, and aqueous ammonia are obtained.

[0037] Furthermore, the liquid phase generated in the gas-liquid phase treatment process can be detoxified and used in the reaction treatment of water and secondary aluminosphate described above, or, if unnecessary, it can be discharged as it has been detoxified.

[0038] (Separation of the gas phase and primary liquid phase of wastewater after hydrogen generation) Hydrogen is generated and collected from the gas phase produced by reacting secondary aluminum dross with water, and the subsequent liquid phase, i.e., a high-ammonia nitrogen salt aqueous solution, is collected in a processing vessel.

[0039] The high ammonia nitrogen salt aqueous solution is transferred to another treatment vessel, and in the treatment vessel, the rotation speed is 40-150 r / min and the air flow rate is 10-30 m³. 3 The reaction is carried out with aeration at a rate of / min for approximately 0.5-3 hours to separate the mixture into ammonia gas (gas phase) and highly saline alkaline water (primary liquid phase).

[0040] • Ammonia water generation The ammonia gas obtained by the separation process described above is introduced into an absorption tower to obtain aqueous ammonia. The resulting aqueous ammonia solution can be used as a metal surface cleaner or as a general raw material for pharmaceuticals.

[0041] (1st liquid phase → 2nd liquid phase) Meanwhile, the primary liquid phase (highly alkaline aqueous solution) of the residual aqueous solution after the separation of ammonia gas as a gaseous component is transferred to another treatment vessel. In this treatment vessel, carbon dioxide is supplied at a rate of 1000-3000 mL / min while stirring the contents of the vessel at a rotation speed of 40-150 r / min until the pH of the primary liquid phase reaches pH 6 or higher to pH 7.

[0042] • Aluminum hydroxide The primary liquid phase after the above treatment is separated by filtration into a solid phase and a liquid phase (secondary liquid phase). The solid phase obtained by this filtration separation is "aluminum hydroxide," which can be used as a general raw material for pharmaceuticals, adsorbents, and pigments.

[0043] (Second liquid phase → Tertiary liquid phase) The secondary liquid phase separated above is transferred to another processing vessel, where carbon dioxide is supplied at a rate of 1000-3000 mL / min while stirring the contents of the vessel at a rotation speed of 40-150 r / min until the pH of the secondary liquid phase is between 5 and less than 6.0.

[0044] Sodium bicarbonate The secondary liquid phase after the above treatment is separated by filtration into a solid phase and a liquid phase (tertiary liquid phase). The solid phase obtained by this filtration separation is "sodium bicarbonate," which can be used as a general raw material for polishing, saponification, and washing.

[0045] (Third liquid phase → fourth liquid phase) The tertiary liquid phase is transferred to another processing vessel, where the tertiary liquid phase is stirred at a rotation speed of 40-150 r / min while maintaining a reaction temperature of 20-25°C and a reaction pressure of 1.85 MPa, until the pH of the tertiary liquid phase is between 3 and less than 5. Carbon dioxide is supplied at a rate of 1000-3000 mL / min with a carbon dioxide solubility of 0.06-0.07 mol / L, and one of the following extraction solvents is added to separate and extract the organic phase (quaternary liquid phase) and the inorganic phase (quaternary liquid phase). The volume ratio is organic phase:inorganic phase = 1:2.

[0046] The above-mentioned extraction solvent includes an extractant and a diluent. The extractant may be one or more of alkyl primary amines, secondary amines, trioctylamines, or trioctylmethylammonium salts. The diluent may be one or more of kerosene, tributyl phosphate, positive pentanol, positive hexanol, positive octanol, or isooctanool.

[0047] Sodium chloride and sodium sulfate The inorganic phase solution described above is heated to 90-100°C and then sent to a self-vapor mechanical compressor (MVR) apparatus. The compressor is operated until the sodium sulfate becomes supersaturated, at which point "sodium sulfate" and the mother liquor are obtained. When the sodium sulfate concentration in the mother liquor drops to 5%, the temperature is lowered to 50-55°C. This mother liquor is then sent to the self-vapor mechanical compressor (MVR) apparatus, the compressor is operated, and supersaturated "sodium chloride" is obtained.

[0048] In the self-contained mechanical compression apparatus described above, the water vapor generated at this stage has had all common toxic and harmful substances removed, so it may be released into the atmosphere or supplied as fresh water equivalent for the subsequent detoxification treatment of secondary aluminodros. The sodium sulfate obtained here can be used as a general raw material for desiccants, and the sodium chloride can be used as a general material for medical products, etc.

[0049] (Fourth liquid phase of the organic phase → inorganic liquid phase / organic liquid phase) The fourth liquid phase of the organic phase described above is transferred to another processing vessel. In this processing vessel, an aqueous ammonia solution (ammonia water) obtained by dissolving the gas phase described in (1) in water is added to the fourth liquid phase. The contents of the processing vessel are stirred at a rotation speed of 40-150 r / min, and back-extraction separation is performed to return the substances extracted into the organic phase from the solvent to the liquid phase. After separation, an organic liquid phase and an inorganic liquid phase are obtained. The volume ratio of the organic liquid phase to the inorganic liquid phase is approximately 1:0.5.

[0050] Ammonium chloride The above organic liquid phase is returned to the tertiary liquid phase. Meanwhile, the above inorganic liquid phase is concentrated and evaporated to obtain ammonium chloride. Ammonium chloride can be used as a general material for plating, fertilizers, etc. Furthermore, the water vapor separated during the evaporation of the inorganic liquid phase has had all common toxic and harmful substances removed, so it can be released into the atmosphere or supplied as fresh water equivalent for the subsequent detoxification treatment of secondary aluminodros.

[0051] Thus, all wastewater used in generating hydrogen from secondary alumina dross is repurposed as a general material, the water component is safely released into the atmosphere as water vapor, and is supplied as fresh water equivalent for the subsequent detoxification treatment of secondary alumina dross. This prevents an increase in wastewater volume by adding new fresh water, and also prevents the concentration of highly alkaline substances from gradually increasing in purity by not adding new fresh water.

[0052] More specifically, it has the following effects: By employing air aeration, ammonia can be removed from the liquid phase. This disrupts the buffering system of the liquid phase, making subsequent pH adjustment easier. Furthermore, the ammonia can be used in subsequent back-extraction, allowing for the complete reuse of wastewater.

[0053] -Solid phase treatment process: Figures 3-7- (Summary) Furthermore, after the reaction step between secondary aluminum dross and water, the solid phase, which is separated from the gas-liquid phase treatment step, is rendered harmless by washing in this solid phase treatment step. This washing removes heavy metal components from the solid phase, including Cl. - F - , K + kaNa + This reduces the concentration of impurity ions. The solid phase after washing is harmless and can be disposed of, but it is particularly suitable for use as a general industrial raw material, such as a cement additive for concrete.

[0054] When using the washed solid phase as a cement additive for concrete, it should be processed as follows: A solid-liquid mixture (slurry) with a solid phase moisture content (mass fraction) of 15-25% is diluted with water to a slurry content (mass) of 40-60%, and 0.001-0.05% cellulose ether is added as a mud stabilizer to prevent the solid phase from settling in the mud suspension. This additive is then added to the concrete cement material at a mass percentage (dry basis) of 1-20%, preferably 5-15%, and most preferably 8-12%.

[0055] Furthermore, the treated water used during the solid phase washing process (referred to as "washing water" in the solid phase washing process) and any added fresh water may be detoxified and then used for washing the solid phase, used as treated water for the reaction between the secondary aluminum dross and water, or discharged if unnecessary. A more detailed explanation is as follows.

[0056] (First cleaning process) Figure 4 The slurry is sent to a pressure filter for solid-liquid separation. The water content of the solid phase after pressure filtration is 15-25%. This solid phase is sent to the first processing vessel, and the liquid phase, along with the liquid phase separated in the second washing process described later, undergoes washing water treatment (1) before being used in the reaction between the secondary aluminum dross and water in the upstream process. Washing water treatment (1), (2), and (3) will be described later.

[0057] The solid phase and "washing water" are placed in the first processing vessel. The solid-liquid ratio (mass ratio) in the first processing vessel at this time is set to 1:3-10 for solid phase:liquid phase. This solid-liquid ratio is finely adjusted within the above range for each processing in the second and third processing vessels. The liquid level inside the vessel 3 at this time is set to be in the range of 50-80% of the internal height.

[0058] The "washing water" in the first washing treatment is obtained by combining the liquid phase separated in the solid-liquid separation described above with the liquid phase separated in the third washing treatment and performing washing water treatment (2).

[0059] The cleaning process begins by activating the agitator blade 5 and the ultrasonic stirrer 4. The rotation speed of the agitator blade 5 is controlled within the range of 20-80 r / min, with the optimal range being 40-60 r / min. Meanwhile, the ultrasonic stirrer 4's ultrasonic frequency is controlled within the range of 20-80 kHz, with the optimal range being 30-50 kHz. While stirring as described above, carbon dioxide supplied via the aeration pipe 12 is ejected from the annular gas phase pipe 11 until the slurry reaches a pH of 6 or higher and less than 7. Furthermore, after the slurry reaches a pH of 6 or higher and less than 7, one or more types of sulfuric acid, nitric acid, or organic acids are injected as a adjusting agent until the pH reaches 2 or higher and less than 6.

[0060] After this, further washing is performed until the tracer ion content is less than 10%. Specific ions (heavy metals or impurity ions) are "selected as tracer ions," samples are taken at predetermined intervals, and the tracer ion content is examined. The first washing process is terminated when the change in tracer ion content between two samples is less than 10%.

[0061] The following explains the "Selection of Tracer Ions" process. The content of heavy metals and impurity ions in the solid phase of the processing vessel is inspected and recorded as A1. A1 / A2 is calculated, and the ion with the highest value is selected as the tracer ion.

[0062] (Second cleaning process) Figure 5 The slurry from the first processing vessel after the first washing treatment is sent to a pressure filter for solid-liquid separation. The solid phase is charged into the second processing vessel, and the liquid phase, as described above, is used as washing water for the solid phase of the first washing treatment after the washing water treatment (1) in this example. The solid phase and "washing water" are charged into the second processing vessel. The liquid level inside the vessel body 3 of the second processing vessel is set to a range of 50-80% of the internal height. The aforementioned "washing water" is the liquid phase that was finally separated from the solid-liquid in the third washing treatment described later, and which has undergone washing water treatment (3).

[0063] The cleaning process begins by activating the agitator blade 5 and the ultrasonic stirrer 4. The rotation speed of the agitator blade 5 is controlled within the range of 20-80 r / min, with the optimal range being 40-60 r / min. Meanwhile, the ultrasonic stirrer 4's ultrasonic frequency is controlled within the range of 20-80 kHz, with the optimal range being 30-50 kHz. While stirring as described above, one or more types of sulfuric acid, nitric acid, or organic acids are added as adjusting agents until the pH reaches 2-6.

[0064] After this, further washing is performed until the tracer ion content is less than 10%. A specific ion (heavy metal or impurity ion) is selected as a tracer ion, and samples are taken at predetermined intervals to check the tracer ion content. The second washing process is terminated when the change in tracer ion content between two samples is less than 10%.

[0065] (Third cleaning process): Figure 6 After the second washing treatment, the slurry from the second processing vessel is sent to a pressure filter for solid-liquid separation. The solid phase is sent to the third processing vessel, and the liquid phase, as described above, in this example, is used for the reaction between the secondary aluminum dross and water in the upstream process after the washing water treatment (2). The solid phase and "washing water" are placed in the third processing vessel. The liquid level inside the vessel body 3 of the third processing vessel is set to a range of 50-80% of the internal height. The aforementioned "washing water" is supplemented with clean water, i.e., fresh water.

[0066] The cleaning process begins by activating the agitator blade 5 and the ultrasonic stirrer 4. The rotation speed of the agitator blade 5 is controlled within the range of 20-80 r / min, with the optimal range being 40-60 r / min. Meanwhile, the ultrasonic stirrer 4's ultrasonic frequency is controlled within the range of 20-80 kHz, with the optimal range being 30-50 kHz. While stirring as described above, one or more types of adjusting agents such as lime hydroxide, sodium hydroxide, oxalic acid, (calcium) carbide slag, and electrostatic slag are injected until the pH is less than 7-12, and ideally 9-11.

[0067] After this, further washing is performed until the tracer ion content is less than 10%. A specific ion (heavy metal or impurity ion) is selected as a tracer ion, and samples are taken at predetermined intervals to check the tracer ion content. When the change in tracer ion content between two samples is less than 10%, the washing is terminated.

[0068] In the third washing process, after the above washing, the slurry is sent to a pressure filter for solid-liquid separation. Pressure filtration is used to reduce the water content of the solid phase to 15-25%, and it is measured whether the solid phase meets, for example, environmental standards. If the solid phase does not meet the standards, the process returns to the washing process in the third washing process and is repeated until it meets the standards.

[0069] On the other hand, the liquid phase separated at this stage undergoes washing water treatment (3) and is used as washing water for the second washing treatment. Furthermore, if the solid phase separated at this stage meets the standards, it can be used as a solid phase raw material. As a raw material, it is particularly suitable for use in concrete materials. Of course, it can also be treated as general waste.

[0070] Wash water treatment (1)(2)(3): Figure 7 Wash water treatment (1), (2), and (3) are carried out in separate facilities, but the treatment itself is the same. First, the pH of the collected liquid phase is measured, and if the pH is less than 6-10, the process proceeds to the solid-liquid separation treatment described later. The reason for using separate facilities is that the properties of the liquid phase collected in each process and the destinations of the wash water from wash water treatment (1), (2), and (3) are different.

[0071] On the other hand, if the collected liquid phase has a pH of 6-10, an adjusting agent is added to adjust it to the pH range of 6-10, and it is allowed to stand for 2-5 hours. After that, solid-liquid separation is performed, and the small amount of solid phase is stored until it reaches a certain amount. Meanwhile, the liquid phase from the solid-liquid separation is used in each treatment. Of course, the liquid phase that has undergone this washing water treatment (1)(2)(3) can also be used as general wastewater.

[0072] By arranging the ultrasonic stirrer 4 and stirring blade 5 together, dispersing the solid phase cleaning process in first to third stages, and adjusting the pH value of the slurry to dissolve heavy metals and impurity ions to the maximum extent possible in the liquid phase, the cleaning efficiency of heavy metals and impurity ions is significantly improved, enabling the detoxification of the solid phase. Furthermore, by providing cleaning water treatment (1)-(3) in each of the first to third cleaning stages to detoxify the cleaning water, it becomes possible to detoxify not only the solid phase but also the liquid phase used to clean the solid phase.

[0073] Furthermore, by employing the tracer ion selection method, it is possible to quickly determine the cleaning effect and whether the heavy metal and impurity ions after cleaning meet the standards. Additionally, by using carbon dioxide as a pH adjuster, it can contribute to the realization of a negative carbon process.

[0074] Thus, in the present invention, when the total mass of secondary aluminum dross and the water used for the reaction (treated water) is taken as 100% in the reaction treatment of secondary aluminum dross and water, approximately 21±4% is harmless solid phase material obtained after solid phase treatment (including solid phase material remaining after the final solid-liquid separation in the slurry during solid phase treatment that requires further treatment), approximately 1.2±0.2% is harmless gas phase material obtained after gas phase treatment, approximately 0.8±0.5% is material used as a general chemical raw material, and approximately 77.2±4.4% can be used as harmless treated water that can be discharged. Note that there are a few percent of solid phase material remaining after the final solid-liquid separation in the slurry during solid phase treatment that requires further treatment, but in this invention, the explanation of how to treat this residual solid phase material has been omitted. [Examples]

[0075] Specific embodiments of the present invention will be described below with reference to Figures 1 and 8, which were referenced above, as well as Figures 2 to 7, which show subroutines for gas-phase and solid-phase treatment in Figure 1. In the following description, the explanation of the treatment vessel shown in Figure 8 will be omitted as it will be redundant with the above. Furthermore, "treated water" in the following description means water used in the treatment of the present invention and that has been rendered harmless, and also means washing water in the solid-phase treatment process. Furthermore, "fresh water" means clean water free of impurities. Furthermore, "slurry" means a mixture of some solid-phase components and liquid-phase components.

[0076] Example 1 -Reaction process between secondary aluminum dross and water (Figure 1)- (Classification process) Secondary aluminum dross was classified so that approximately 3.5% or more of the material had a particle size of 125 μm or larger, with the remainder being less than 125 μm. The portion exceeding 125 μm was sent for crushing or other processing, while the portion below 125 μm was supplied for subsequent processing.

[0077] (Deoxidation - secondary aluminum dross and water treatment) Nitrogen was blown into the treatment vessel used for the reaction between secondary aluminum dross and water to deoxidize it. The solid-liquid ratio (mass ratio) of secondary aluminum dross to treated water was set to 3.5 parts treated water to 1 part secondary aluminum dross. After adding approximately one-third of the specified amount of treated water to the treatment vessel, the secondary aluminum dross was added, and the remaining two-thirds of the treated water was added at the same time, followed by stirring for three minutes.

[0078] (Reaction process) The pressure inside the treatment vessel was set to atmospheric pressure and the initial temperature to 15°C when the secondary aluminum dross and treated water were introduced in the solid-liquid ratio (mass ratio 1:3.5) specified above. During the "induction phase," calcium hydroxide was added until supersaturated, adjusting the pH to 12.5. Furthermore, to accelerate the reaction, catalyst equivalent to 3% of the mass ratio of the secondary aluminosulfate was added. The catalyst composition (mass fraction) was 10% sodium carbonate, 20% sodium hydroxide, 10% carbide slag, and 0.03% sodium stannate.

[0079] When the "acceleration phase" was reached and the temperature inside the processing vessel reached 75°C, fresh water for cooling was flowed into the water-cooled jacket 13. The flow rate of the fresh water for cooling was controlled so that the rate of temperature rise inside the processing vessel was 1.2°C / min. Once the "deceleration phase" was reached, meaning the heating rate began to decrease, the flow rate of fresh water for cooling was gradually reduced until it was completely stopped. The internal temperature of the processing vessel when the supply of fresh water for cooling was stopped was approximately 87°C. When the temperature inside the processing vessel began to drop from the above temperature, a controlled flow rate of fresh water (91°C) for heat retention was circulated through the water-cooled jacket 13 to maintain the temperature of 87-88°C. In this example, for example, the fresh water for heat retention is circulated and supplied from the processing vessel in the heat treatment area.

[0080] In the reaction process in Example 1, it took approximately 22 hours for the metallic aluminum and the aluminum nitride in the secondary aluminum dross to react almost completely. The reaction was terminated when the clinker levels of metallic aluminum and aluminum nitride in the slurry were measured and fell below a predetermined value. The liquid phase, which is separated from the gas phase generated during the reaction process, is used in the next gas phase treatment.

[0081] -Gas-liquid phase treatment process (Figure 2)- (Separation of hydrogen from high-ammonia nitrogen salt aqueous solution) Hydrogen was generated and collected from the gas phase produced during the reaction treatment of secondary aluminum dross with water. The purity (mass fraction) of the hydrogen at this time was 99.99%. The subsequent liquid phase, i.e., a high-ammonia nitrogen salt aqueous solution, was collected in an aeration treatment vessel equipped with a porous ceramic at the bottom.

[0082] The components of the high-ammonia nitrogen salt aqueous solution in Example 1 are as follows: pH14 Hydroxide ion concentration: 0.6 mol / L Aluminum ion concentration: 15 g / L Total salt concentration: 12% Chloride ion concentration: 27.7 g / L Ammonia nitrogen concentration: 2000 mg / L Sulfide and thiosulfate concentrations: 1.98 g / L and 13.5 g / L

[0083] (Separation of ammonia and primary liquid phase) The high-ammonia nitrogen salt aqueous solution was transferred to another treatment vessel, which was set up as follows for processing. Subsequently, gas-liquid separation was performed, and the ammonia in the gas phase was passed through an absorption tower to obtain "ammonia water," while the liquid phase (primary liquid phase) was transferred to another treatment vessel for the next treatment. Rotation speed of the processing kettle: 40 r / min Airflow rate for aeration: 10 m 3 / min Aeration time: 1 hour

[0084] (1st liquid phase → 2nd liquid phase) The primary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "aluminum hydroxide" as the solid phase, while the liquid phase (secondary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1000 mL / min Rotation speed of the processing kettle: 40 r / min Continue the process under the above conditions until the pH reaches 7.

[0085] (Second liquid phase - Tertiary liquid phase) The secondary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "sodium bicarbonate" as the solid phase, while the liquid phase (tertiary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1200 mL / min Rotation speed of the processing kettle: 40 r / min Continue the process under the above conditions until the pH reaches 6.

[0086] (Third liquid phase → fourth liquid phase) The tertiary liquid phase was transferred to another processing vessel, which was set up as follows to process the material and obtain "sodium chloride" and "sodium sulfate." Meanwhile, the remaining tertiary liquid phase was extracted and separated to obtain the quaternary liquid phase of the organic phase and the quaternary liquid phase of the inorganic phase. The quaternary liquid phase of the organic phase was then transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1100 mL / min Rotation speed of the processing kettle: 40 r / min Extraction solvent: Extractant: alkyl primary amine; Diluent: kerosene Add the organic phase and inorganic phase so that their volume ratio is approximately 1:2. Reaction temperature: 20°C Processing vessel internal pressure: 1.85 MPa Solubility of carbon dioxide: 0.07 mol / L Continue the process under the above conditions until the pH reaches 3.

[0087] The fourth liquid phase of the inorganic phase described above was taken from the bottom of the processing vessel and sent to a self-steam mechanical compressor (MVR) apparatus. In this apparatus, it was heated to 100°C, and the compressor was operated to supersaturate the sodium sulfate to obtain "sodium sulfate" and "mother liquor".

[0088] As described above, once the sodium sulfate concentration in the mother liquor was reduced to 5% by the extraction of sodium sulfate, the temperature was lowered to 50°C, and the mother liquor was sent to another self-vapor mechanical compression (MVR) apparatus. In this apparatus, the compressor was operated to concentrate and supersaturate the mixture to obtain sodium chloride. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0089] (Fourth liquid phase of the organic phase → inorganic liquid phase / organic liquid phase) The following conditions were used to obtain "ammonium chloride". The above-mentioned "aqueous ammonia solution" was added to the fourth liquid phase of the organic phase so that the volume ratio of organic phase to inorganic phase was approximately 1:0.5. Back-extraction and separation treatment was performed on the fourth liquid phase of the organic phase after the addition of an aqueous ammonia solution, with the treatment vessel rotation speed set to 40 r / min. The inorganic liquid phase separated above was concentrated and evaporated to obtain ammonium chloride, while the organic liquid phase was returned to the tertiary liquid phase. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0090] The wastewater treated by the gas phase in Example 1 was as follows. All obtained general chemical raw materials (excluding ammonia water) had a purity of 90% or higher, and the entire amount of high-ammonia nitrogen salt aqueous solution was treated. Aluminum hydroxide 1.30 t Sodium bicarbonate 2.20 t Ammonium chloride 0.10 t Sodium chloride 0.80 t Sodium sulfate 1.40 t Ammonia solution 0.30 t (concentration range 5-15%)

[0091] -Solid-phase treatment process (Figures 3-7)- (First washing process: Figures 3, 4, and 7) Meanwhile, the secondary aluminum dross is reacted with water to separate the gas-liquid phase from the solid phase, and the solid phase is sent to the first processing vessel. At this time, the water content of the solid phase was 18%. In the first treatment vessel, the treated water from the washing water treatment (1) and (2) was added as washing water at a mass ratio of 3.4 to the solid phase 1, and the liquid level in the first treatment vessel was raised to 55%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. In addition, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Carbon dioxide was supplied to the processing vessel, and the pH was adjusted to 6.5. After the pH reached 6.5, nitric acid was added as a adjusting agent to adjust the pH to 3. The solution was adjusted to pH 3 and then washed for 18 minutes. During the 18-minute washing time, chloride ions (Cl - ) was selected as a tracer ion, and samples were taken at 5-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to less than 10% between two consecutive samplings, and the washing process was repeated after adjusting the pH to 3 until the content fell below 10%. The first washing process was terminated when the content fell below 10%.

[0092] (Second cleaning process: Figures 3, 5, and 7) The slurry sent from the first treatment kettle was subjected to solid-liquid separation. The solid phase was sent to the second treatment kettle, and the liquid phase was sent to the washing water treatment (1) respectively. The solid phase and the treated water from the washing water treatment (3) were injected into the second treatment kettle as washing water, and the liquid level height in the second treatment kettle was set to 55%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. Also, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Nitric acid was added as an adjusting agent to adjust the pH to 2. After adjusting the pH to 2, it was washed for 22 minutes. During the 22-minute washing time, chloride ions (Cl - ) were selected as tracer ions, sampled at 5-minute intervals, and the content of the tracer ions was inspected. The washing after adjusting the pH to 2 was repeated until the change in the chloride ion content became less than 10% between two consecutive samplings. When it became less than 10%, the secondary washing treatment was terminated.

[0093] (Tertiary washing treatment Figures 3, 6, 7)- The slurry sent from the second treatment kettle was subjected to solid-liquid separation. The solid phase was sent to the third treatment kettle, and the liquid phase was sent to the washing water treatment (2) respectively. The solid phase and pure water were injected into the third treatment kettle as washing water, and the liquid level height in the third treatment kettle was set to 55%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. Also, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Lime water was added as an adjusting agent to adjust the pH to 8. After adjusting the pH to 8, it was washed for 22 minutes. During the 22-minute washing time, chloride ions (Cl - ) were selected as tracer ions, sampled at 5-minute intervals, and the content of the tracer ions was inspected. The washing after adjusting the pH to 8 was repeated until the change in the chloride ion content became less than 10% between two consecutive samplings. When it became less than 10%, the next treatment was carried out. In the next step, solid-liquid separation was performed on the slurry in the third processing vessel. The liquid phase after solid-liquid separation was sent to the washing water treatment (3), and the treated water from the washing water treatment (3) was reused as washing water for the second washing treatment. On the other hand, the solid phase after the solid-liquid separation was tested for heavy metal and impurity ion content using a prescribed testing method. If it met the prescribed standards, the process was terminated. If it did not meet the standards, the process was repeated by returning to the initial washing after solid-liquid separation in the third washing process (returning the solid phase) and repeating the subsequent processes.

[0094] (Application of detoxified solid phase to concrete materials) Solid phases that meet the prescribed standards can be disposed of as general waste, but in this example, they were reused as a cement additive for concrete. The solid phase water content (mass fraction) after solid-liquid separation was 22%. This water-containing solid-liquid mixture (slurry) is diluted with water to a slurry content (by mass) of 50%, and 0.003% cellulose ether is added as an auxiliary material to stabilize the mud and prevent the solid phase in the mud suspension from settling. The aforementioned auxiliary material was added to the cement material of the concrete at a mass ratio of 18% (wet basis).

[0095] Example 2 -Reaction process between secondary aluminum dross and water (Figure 1)- (Classification process) Secondary aluminum dross was classified so that approximately 4.2% or more of the material had a particle size of 125 μm or larger, with the remainder being less than 125 μm. The portion exceeding 125 μm was sent for crushing or other processing, while the portion below 125 μm was supplied for subsequent processing.

[0096] (Deoxidation - secondary aluminum dross and water treatment) Nitrogen was blown into the treatment vessel used for the reaction between secondary aluminum dross and water to deoxidize it. The solid-liquid ratio (mass ratio) of secondary aluminum dross to treated water was set to 3.8 parts treated water to 1 part secondary aluminum dross. After adding approximately one-third of the specified amount of treated water to the treatment vessel, the secondary aluminum dross was added, and the remaining two-thirds of the treated water was added at the same time, followed by stirring for three minutes.

[0097] (Reaction process) The pressure inside the treatment vessel was set to atmospheric pressure and the initial temperature to 24°C when the secondary aluminum dross and treated water were introduced in the solid-liquid ratio (mass ratio 1:3.8) specified above. During the "induction phase," calcium hydroxide was added until supersaturated to adjust the pH to 12.3. Furthermore, to accelerate the reaction, catalyst equivalent to 5% of the mass ratio of the secondary aluminosulfate was added. The catalyst composition (mass fraction) was 12% sodium carbonate, 18% sodium hydroxide, 14% carbide slag, and 0.04% sodium stannate.

[0098] When the "acceleration phase" was reached and the temperature inside the processing vessel reached 88°C, fresh water for cooling was flowed into the water-cooled jacket 13. The flow rate of the fresh water for cooling was controlled so that the rate of temperature rise inside the processing vessel was 0.5°C / min. Once the "deceleration phase" was reached, meaning the heating rate began to decrease, the flow rate of fresh water for cooling was gradually reduced until it was completely stopped. The internal temperature of the processing vessel when the supply of fresh water for cooling was stopped was approximately 93°C. When the temperature inside the processing vessel began to drop from the above temperature, a controlled flow rate of fresh water (95°C) for heat retention was circulated through the water-cooled jacket 13 to maintain the temperature of 92-93°C. In this example, for example, the fresh water for heat retention is circulated and supplied from the processing vessel in the heat treatment area.

[0099] In the reaction process in Example 2, it took approximately 27 hours for the metallic aluminum and the aluminum nitride in the secondary aluminum dross to react almost completely. The reaction was terminated when the clinker levels of metallic aluminum and aluminum nitride in the slurry were measured and fell below a predetermined value. The liquid phase, which is separated from the gas phase generated during the reaction process, is used in the next gas phase treatment.

[0100] -Gas-liquid phase treatment process (Figure 2)- (Separation of hydrogen from high-ammonia nitrogen salt aqueous solution) Hydrogen was generated and collected from the gas phase produced during the reaction treatment of secondary aluminum dross with water. The purity (mass fraction) of the hydrogen at this time was 99.99%. The subsequent liquid phase, i.e., a high-ammonia nitrogen salt aqueous solution, was collected in an aeration treatment vessel equipped with a porous ceramic at the bottom.

[0101] The components of the high-ammonia nitrogen salt aqueous solution in Example 2 are as follows: pH14 Hydroxide ion concentration: 0.55 mol / L Aluminum ion concentration: 16 g / L Total salt concentration: 13% Chloride ion concentration: 28 g / L Ammonia nitrogen concentration: 1900 mg / L Sulfide and thiosulfate concentrations: 1.88 g / L and 12 g / L

[0102] (Separation of ammonia and primary liquid phase) The high-ammonia nitrogen salt aqueous solution was transferred to another treatment vessel, which was set up as follows for processing. Subsequently, gas-liquid separation was performed, and the ammonia in the gas phase was passed through an absorption tower to obtain "ammonia water," while the liquid phase (primary liquid phase) was transferred to another treatment vessel for the next treatment. Rotation speed of the processing kettle: 50 r / min Airflow rate for aeration: 12 m 3 / min Aeration time: 1.5 hours

[0103] (1st liquid phase → 2nd liquid phase) The primary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "aluminum hydroxide" as the solid phase, while the liquid phase (secondary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1200 mL / min Rotation speed of the processing kettle: 30 r / min Continue the process under the above conditions until the pH reaches 7.

[0104] (Second liquid phase - Tertiary liquid phase) The secondary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "sodium bicarbonate" as the solid phase, while the liquid phase (tertiary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1300 mL / min Rotation speed of the processing kettle: 55 r / min Continue the process under the above conditions until the pH reaches 6.

[0105] (Third liquid phase → fourth liquid phase) The tertiary liquid phase was transferred to another processing vessel, which was set up as follows to process the material and obtain "sodium chloride" and "sodium sulfate." Meanwhile, the remaining tertiary liquid phase was extracted and separated to obtain the quaternary liquid phase of the organic phase and the quaternary liquid phase of the inorganic phase. The quaternary liquid phase of the organic phase was then transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1450 mL / min Rotation speed of the processing kettle: 50 r / min Extraction solvent: Extractant: Secondary amine; Diluent: Tributyl phosphate Add the organic phase and inorganic phase so that their volume ratio is approximately 1:2.2. Reaction temperature: 21°C Processing vessel internal pressure: 1.80 MPa Solubility of carbon dioxide: 0.065 mol / L Continue the process under the above conditions until the pH reaches 3.

[0106] The fourth liquid phase of the inorganic phase described above was taken from the bottom of the processing vessel and sent to a self-steam mechanical compressor (MVR) apparatus. In this apparatus, it was heated to 100°C, and the compressor was operated to supersaturate the sodium sulfate to obtain "sodium sulfate" and "mother liquor".

[0107] As described above, once the sodium sulfate concentration in the mother liquor was reduced to 5% by the extraction of sodium sulfate, the temperature was lowered to 50°C, and the mother liquor was sent to another self-vapor mechanical compression (MVR) apparatus. In this apparatus, the compressor was operated to concentrate and supersaturate the mixture to obtain sodium chloride. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0108] (Fourth liquid phase of the organic phase → inorganic liquid phase / organic liquid phase) The following conditions were used to obtain "ammonium chloride". The above-mentioned "aqueous ammonia solution" was added to the fourth liquid phase of the organic phase so that the volume ratio of organic phase to inorganic phase was approximately 1:0.45. Back-extraction and separation treatment was performed on the fourth liquid phase of the organic phase after the addition of an aqueous ammonia solution, with the rotation speed of the processing vessel set to 35 r / min. The inorganic liquid phase separated above was concentrated and evaporated to obtain ammonium chloride, while the organic liquid phase was returned to the tertiary liquid phase. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0109] The wastewater treated by the gas phase in Example 2 was as follows. All obtained general chemical raw materials (excluding ammonia water) had a purity of 90% or higher, and the entire amount of high-ammonia nitrogen salt aqueous solution was treated. Aluminum hydroxide 1.50 t Sodium bicarbonate 2.00 t Ammonium chloride 0.09 t Sodium chloride 0.90 t Sodium sulfate 1.30 t Ammonia solution 0.33 t (concentration range 5-15%)

[0110] -Solid-phase treatment process (Figures 3-7)- (First washing process: Figures 3, 4, and 7) Meanwhile, the secondary aluminum dross is reacted with water to separate the gas-liquid phase from the solid phase, and the solid phase is sent to the first processing vessel. At this time, the water content of the solid phase was 22%. In the first processing vessel, the treated water from the washing water treatment (1) and (2) was added as washing water at a mass ratio of 4.2 to the solid phase 1, and the liquid level in the first processing vessel was raised to 60%. The rotation speed of the stirring blade 5 was controlled to 60 r / min. In addition, the frequency of the ultrasonic stirrer 4 was controlled to 60 kHz. Carbon dioxide was supplied to the processing vessel, and the pH was adjusted to 6.8. After the pH reached 6.8, nitric acid was added as a adjusting agent to adjust the pH to 3.5. The solution was adjusted to pH 3.5 and then washed for 25 minutes. During the 25-minute washing time, chloride ions (Cl - ) was selected as a tracer ion, and samples were taken at 5-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 3.5 and washed repeatedly between two consecutive samplings until it fell below 10%. The first washing process was terminated when the chloride ion content fell below 10%.

[0111] (Second cleaning process: Figures 3, 5, and 7) The slurry sent from the first processing vessel was subjected to solid-liquid separation. The solid phase was sent to the second processing vessel, and the liquid phase was sent to the washing water treatment (1). The solid phase and the treated water from the washing water treatment (3) are injected into the second treatment vessel as washing water, and the liquid level in the second treatment vessel is raised to 60%. The rotation speed of the stirring blade 5 was controlled to 60 r / min. The frequency of the ultrasonic stirrer 4 was also controlled to 60 kHz. Nitric acid was added as a adjusting agent to adjust the pH to 2.5. The solution was adjusted to pH 2.5 and then washed for 28 minutes. During the 28-minute washing time, chloride ions (Cl - ) was selected as a tracer ion, and samples were taken at 5-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 2.5 and washed repeatedly between two consecutive samplings until it fell below 10%. The second washing process was terminated when the chloride ion content fell below 10%.

[0112] (Third cleaning process: Figures 3, 6, and 7) The slurry sent from the second processing vessel was subjected to solid-liquid separation. The solid phase was sent to the third processing vessel, and the liquid phase was sent to the washing water treatment (2). The solid phase and fresh water were injected into the third processing vessel as washing water, and the liquid level in the third processing vessel was raised to 60%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. In addition, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Calcium hydroxide was added as a adjusting agent to adjust the pH to 9. The solution was adjusted to pH 9 and then washed for 25 minutes. During the 25-minute washing time, chloride ions (Cl - ) was selected as a tracer ion, and samples were taken at 5-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 9 and washed repeatedly between two consecutive samplings until it fell below 10%. Once it fell below 10%, the next treatment was performed. In the next step, solid-liquid separation was performed on the slurry in the third processing vessel. The liquid phase after solid-liquid separation was sent to the washing water treatment (3), and the treated water from the washing water treatment (3) was reused as washing water for the second washing treatment. On the other hand, the solid phase after the solid-liquid separation was tested for heavy metal and impurity ion content using a prescribed testing method. If it met the prescribed standards, the process was terminated. If it did not meet the standards, the process was repeated by returning to the initial washing after solid-liquid separation in the third washing process (returning the solid phase) and repeating the subsequent processes.

[0113] (Application of detoxified solid phase to concrete materials) Solid phases that meet the prescribed standards can be disposed of as general waste, but in this example, they were reused as a cement additive for concrete. The solid phase water content (mass fraction) after solid-liquid separation was 24%. This water-containing solid-liquid mixture (slurry) is diluted with water to a slurry content (by mass) of 50%, and 0.0025% cellulose ether is added as an auxiliary material to stabilize the mud and prevent the solid phase in the mud suspension from settling. The aforementioned auxiliary material was added to the cement material of the concrete at a mass ratio of 22% (wet basis).

[0114] Example 3 -Reaction process between secondary aluminum dross and water (Figure 1)- (Classification process) Secondary aluminum dross was classified so that approximately 5.7% or more of the material had a particle size of 125 μm or larger, with the remainder being less than 125 μm. The portion exceeding 125 μm was sent for crushing or other processing, while the portion below 125 μm was supplied for subsequent processing.

[0115] (Deoxidation - secondary aluminum dross and water treatment) Nitrogen was blown into the treatment vessel used for the reaction between secondary aluminum dross and water to deoxidize it. The solid-liquid ratio (mass ratio) of secondary aluminum dross to treated water was set to 4.2 parts treated water to 1 part secondary aluminum dross. After adding approximately one-third of the specified amount of treated water to the treatment vessel, the secondary aluminum dross was added, and the remaining two-thirds of the treated water was added at the same time, followed by stirring for four minutes.

[0116] (Reaction process) The pressure inside the treatment vessel was set to atmospheric pressure and the initial temperature to 21°C when the secondary aluminum dross and treated water were introduced in the solid-liquid ratio (mass ratio 1:4.2) specified above. During the "induction phase," calcium hydroxide was added until supersaturated to adjust the pH to 12.6. Furthermore, to accelerate the reaction, catalyst equivalent to 5% of the mass ratio of the secondary aluminosulfate was added. The catalyst composition (mass fraction) was 8% sodium carbonate, 24% sodium hydroxide, 12% carbide slag, and 0.04% sodium stannate.

[0117] When the "acceleration phase" was reached and the temperature inside the processing vessel reached 92°C, fresh water for cooling was flowed into the water-cooled jacket 13. The flow rate of the fresh water for cooling was controlled so that the rate of temperature rise inside the processing vessel was 0.9°C / min. Once the "deceleration phase" was reached, meaning the heating rate began to decrease, the flow rate of fresh water for cooling was gradually reduced until it was completely stopped. The internal temperature of the processing vessel when the supply of fresh water for cooling was stopped was approximately 91°C. When the temperature inside the processing vessel began to drop from the above temperature, a controlled flow rate of fresh water (95°C) for heat retention was circulated through the water-cooled heating jacket 13 to maintain the above temperature of 90-91°C. In this example, for example, the fresh water for heat retention is circulated and supplied from the processing vessel in the heat treatment area.

[0118] In the reaction process in Example 3, it took approximately 33 hours for the metallic aluminum and the aluminum nitride in the secondary aluminum dross to react almost completely. The reaction was terminated when the clinker levels of metallic aluminum and aluminum nitride in the slurry were measured and fell below a predetermined value. The liquid phase, which is separated from the gas phase generated during the reaction process, is used in the next gas phase treatment.

[0119] -Gas phase treatment process (Figure 2)- (Separation of hydrogen from high-ammonia nitrogen salt aqueous solution) Hydrogen was generated and collected from the gas phase produced during the reaction treatment of secondary aluminum dross with water. The purity (mass fraction) of the hydrogen at this time was 99.99%. The subsequent liquid phase, i.e., a high-ammonia nitrogen salt aqueous solution, was collected in an aeration treatment vessel equipped with a porous ceramic at the bottom.

[0120] The components of the high-ammonia nitrogen salt aqueous solution in Example 3 are as follows: pH14 Hydroxide ion concentration: 0.57 mol / L Aluminum ion concentration: 13 g / L Total salt concentration: 16% Chloride ion concentration: 25 g / L Ammonia nitrogen concentration: 1888 mg / L Sulfide and thiosulfate concentrations: 1.7 g / L and 11 g / L

[0121] (Separation of ammonia and primary liquid phase) The high-ammonia nitrogen salt aqueous solution was transferred to another treatment vessel, which was set up as follows for processing. Subsequently, gas-liquid separation was performed, and the ammonia in the gas phase was passed through an absorption tower to obtain "ammonia water," while the liquid phase (primary liquid phase) was transferred to another treatment vessel for the next treatment. Rotation speed of the processing kettle: 46 r / min Airflow rate for aeration: 13 m 3 / min Aeration time: 1.3 h

[0122] (1st liquid phase → 2nd liquid phase) The primary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "aluminum hydroxide" as the solid phase, while the liquid phase (secondary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1314 mL / min Rotation speed of the processing kettle: 38 r / min Continue the process under the above conditions until the pH reaches 7.

[0123] (Second liquid phase - Tertiary liquid phase) The secondary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "sodium bicarbonate" as the solid phase, while the liquid phase (tertiary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1500 mL / min Processing kettle rotation speed: 45 r / min Continue the process under the above conditions until the pH reaches 6.

[0124] (Third liquid phase → fourth liquid phase) The tertiary liquid phase was transferred to another processing vessel, which was set up as follows to process the material and obtain "sodium chloride" and "sodium sulfate." Meanwhile, the remaining tertiary liquid phase was extracted and separated to obtain the quaternary liquid phase of the organic phase and the quaternary liquid phase of the inorganic phase. The quaternary liquid phase of the organic phase was then transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1520 mL / min Rotation speed of the processing kettle: 54 r / min Extraction solvent: Extractant: Trioctylamine; Diluent: Pentamol Add the organic phase and inorganic phase so that their volume ratio is approximately 1:2.3. Reaction temperature: 23°C Processing vessel pressure: 1.77 MPa Solubility of carbon dioxide: 0.06 mol / L Continue the process under the above conditions until the pH reaches 3.

[0125] The fourth liquid phase of the inorganic phase described above was taken from the bottom of the processing vessel and sent to a self-steam mechanical compressor (MVR) apparatus. In this apparatus, it was heated to 100°C, and the compressor was operated to supersaturate the sodium sulfate to obtain "sodium sulfate" and "mother liquor".

[0126] As described above, once the sodium sulfate concentration in the mother liquor was reduced to 5% by the extraction of sodium sulfate, the temperature was lowered to 50°C, and the mother liquor was sent to another self-vapor mechanical compression (MVR) apparatus. In this apparatus, the compressor was operated to concentrate and supersaturate the mixture to obtain sodium chloride. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0127] (Fourth liquid phase of the organic phase → inorganic liquid phase / organic liquid phase) The following conditions were used to obtain "ammonium chloride". The above-mentioned "aqueous ammonia solution" was added to the fourth liquid phase of the organic phase so that the volume ratio of organic phase to inorganic phase was approximately 1:0.43. Back-extraction and separation treatment was performed on the fourth liquid phase of the organic phase after the addition of an aqueous ammonia solution, with the rotation speed of the treatment vessel set to 48 r / min. The inorganic liquid phase separated above was concentrated and evaporated to obtain ammonium chloride, while the organic liquid phase was returned to the tertiary liquid phase. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0128] The wastewater treated by the gas phase in Example 3 was as follows. All obtained general chemical raw materials (excluding ammonia water) had a purity of 90% or higher, and the entire amount of high-ammonia nitrogen salt aqueous solution was treated. Aluminum hydroxide 1.20 t Sodium bicarbonate 1.90 t Ammonium chloride 0.07 t Sodium chloride 0.70 t Sodium sulfate 1.10 t Ammonia solution 0.30 t (concentration range 5-15%)

[0129] -Solid-phase treatment process (Figures 3-7)- (First washing process: Figures 3, 4, and 7) Meanwhile, the secondary aluminum dross is reacted with water to separate the gas-liquid phase from the solid phase, and the solid phase is sent to the first processing vessel. At this time, the water content of the solid phase was 22%. In the first treatment vessel, the treated water from the washing water treatment (1) and (2) was added as washing water at a mass ratio of 4.2 to the solid phase 1, and the liquid level in the first treatment vessel was raised to 65%. The rotation speed of the stirring blade 5 was controlled to 60 r / min. In addition, the frequency of the ultrasonic stirrer 4 was controlled to 35 kHz. Carbon dioxide was supplied to the processing vessel, and the pH was adjusted to 6.2. After the pH reached 6.2, nitric acid was added as a adjusting agent to adjust the pH to 3.8. The solution was adjusted to pH 3.8 and then washed for 32 minutes. During the 25-minute washing time, chloride ions (Cl - ) was selected as the tracer ion, and samples were taken at 8-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 3.8 and washed repeatedly between two consecutive samplings until it fell below 10%. The first washing process was terminated when the chloride ion content fell below 10%.

[0130] (Second cleaning process: Figures 3, 5, and 7) The slurry sent from the first processing vessel was subjected to solid-liquid separation. The solid phase was sent to the second processing vessel, and the liquid phase was sent to the washing water treatment (1). The solid phase and the treated water from the washing water treatment (3) are injected into the second treatment vessel as washing water, and the liquid level in the second treatment vessel is raised to 65%. The rotation speed of the stirring blade 5 was controlled to 60 r / min. The frequency of the ultrasonic stirrer 4 was also controlled to 35 kHz. Nitric acid was added as a adjusting agent to adjust the pH to 3.2. The solution was adjusted to pH 3.2 and then washed for 28 minutes. During the 28-minute washing time, chloride ions (Cl - ) was selected as the tracer ion, and samples were taken at 8-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 3.2 and washed repeatedly between two consecutive samplings until it fell below 10%. The second washing process was terminated when the chloride ion content fell below 10%.

[0131] (Third cleaning process: Figures 3, 6, and 7) The slurry sent from the second processing vessel was subjected to solid-liquid separation. The solid phase was sent to the third processing vessel, and the liquid phase was sent to the washing water treatment (2). The solid phase and fresh water were injected into the third processing vessel as washing water, and the liquid level in the third processing vessel was raised to 65%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. Additionally, the frequency of the ultrasonic stirrer 4 was controlled to 35 kHz. Carbide slag was added as a adjusting agent to adjust the pH to 10. The solution was adjusted to pH 10 and then washed for 28 minutes. During the 28-minute washing time, chloride ions (Cl - ) was selected as the tracer ion, and samples were taken at 8-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 10 and washed repeatedly between two consecutive samplings until it fell below 10%. Once it fell below 10%, the next treatment was performed. In the next step, solid-liquid separation was performed on the slurry in the third processing vessel. The liquid phase after solid-liquid separation was sent to the washing water treatment (3), and the treated water from the washing water treatment (3) was reused as washing water for the second washing treatment. On the other hand, the solid phase after the solid-liquid separation was tested for heavy metal and impurity ion content using a prescribed testing method. If it met the prescribed standards, the process was terminated. If it did not meet the standards, the process was repeated by returning to the initial washing after solid-liquid separation in the third washing process (returning the solid phase) and repeating the subsequent processes.

[0132] (Application of detoxified solid phase to concrete materials) Solid phases that meet the prescribed standards can be disposed of as general waste, but in this example, they were reused as a cement additive for concrete. The solid phase water content (mass fraction) after solid-liquid separation was 18%. This water-containing solid-liquid mixture (slurry) is diluted with water to a slurry content (by mass) of 50%, and 0.003% cellulose ether is added as an auxiliary material to stabilize the mud and prevent the solid phase in the mud suspension from settling. The aforementioned auxiliary material was added to the cement material of the concrete at a mass ratio of 21% (wet basis).

[0133] Example 4 -Reaction process between secondary aluminum dross and water (Figure 1)- (Classification process) Secondary aluminum dross was classified so that approximately 2.6% or more of the material had a particle size of 125 μm or larger, with the remainder being less than 125 μm. The portion exceeding 125 μm was sent for crushing or other processing, while the portion below 125 μm was supplied for subsequent processing.

[0134] (Deoxidation - secondary aluminum dross and water treatment) Nitrogen was blown into the treatment vessel used for the reaction between secondary aluminum dross and water to deoxidize it. The solid-liquid ratio (mass ratio) of secondary aluminum dross to treated water was set to 3.8 parts treated water to 1 part secondary aluminum dross. After adding approximately one-third of the specified amount of treated water to the treatment vessel, the secondary aluminum dross was added, and the remaining two-thirds of the treated water was added at the same time, followed by stirring for four minutes.

[0135] (Reaction process) The pressure inside the treatment vessel was set to atmospheric pressure and the initial temperature to 18°C ​​when the secondary aluminum dross and treated water were introduced in the solid-liquid ratio (mass ratio 1:3.8) specified above. During the "induction phase," calcium hydroxide was added until supersaturated to adjust the pH to 12.8. Furthermore, to accelerate the reaction, catalyst equivalent to 4% of the mass ratio of the secondary aluminosulfate was added. The catalyst composition (mass fraction) was 5% sodium carbonate, 16% sodium hydroxide, 14% carbide slag, and 0.01% sodium stannate.

[0136] When the "acceleration phase" was reached and the temperature inside the processing vessel reached 82°C, fresh water for cooling was flowed into the water-cooled jacket 13. The flow rate of the fresh water for cooling was controlled so that the rate of temperature rise inside the processing vessel was 1.1°C / min. Once the "deceleration phase" was reached, meaning the heating rate began to decrease, the flow rate of fresh water for cooling was gradually reduced until it was completely stopped. The internal temperature of the processing vessel when the supply of fresh water for cooling was stopped was approximately 84°C. When the temperature inside the processing vessel began to drop from the above temperature, a controlled flow rate of fresh water (87°C) for heat retention was circulated through the water-cooled jacket 13 to maintain the temperature of 84-85°C. In this example, for example, the fresh water for heat retention is circulated and supplied from the processing vessel in the heat treatment area.

[0137] In the reaction process in Example 4, it took approximately 16 hours for the metallic aluminum and the aluminum nitride in the secondary aluminum dross to react almost completely. The reaction was terminated when the clinker levels of metallic aluminum and aluminum nitride in the slurry were measured and fell below a predetermined value. The liquid phase, which is separated from the gas phase generated during the reaction process, is used in the next gas phase treatment.

[0138] -Gas-liquid phase treatment process (Figure 2)- (Separation of hydrogen from high-ammonia nitrogen salt aqueous solution) Hydrogen was generated and collected from the gas phase produced during the reaction treatment of secondary aluminum dross with water. The purity (mass fraction) of the hydrogen at this time was 99.99%. The subsequent liquid phase, i.e., a high-ammonia nitrogen salt aqueous solution, was collected in an aeration treatment vessel equipped with a porous ceramic at the bottom.

[0139] The components of the high-ammonia nitrogen salt aqueous solution in Example 4 are as follows: pH14 Hydroxide ion concentration: 0.59 mol / L Aluminum ion concentration: 15 g / L Total salt concentration: 18% Chloride ion concentration: 29.0 g / L Ammonia nitrogen concentration: 1650 mg / L Sulfide and thiosulfate concentrations: 1.5 g / L and 16 g / L

[0140] (Separation of ammonia and primary liquid phase) The high-ammonia nitrogen salt aqueous solution was transferred to another treatment vessel, which was set up as follows for processing. Subsequently, gas-liquid separation was performed, and the ammonia in the gas phase was passed through an absorption tower to obtain "ammonia water," while the liquid phase (primary liquid phase) was transferred to another treatment vessel for the next treatment. Rotation speed of the processing kettle: 48 r / min Airflow rate for aeration: 15 m 3 / min Aeration time: 1.5 hours

[0141] (1st liquid phase → 2nd liquid phase) The primary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "aluminum hydroxide" as the solid phase, while the liquid phase (secondary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1517 mL / min Rotation speed of the processing kettle: 44 r / min Continue the process under the above conditions until the pH reaches 7.

[0142] (Second liquid phase - Tertiary liquid phase) The secondary liquid phase was transferred to another processing vessel, which was set up as follows for processing. After that, solid-liquid separation was performed to obtain "sodium bicarbonate" as the solid phase, while the liquid phase (tertiary liquid phase) was transferred to another processing vessel for the next step. Carbon dioxide flow rate: 1750 mL / min Rotation speed of processing kettle: 56 r / min Continue the process under the above conditions until the pH reaches 6.

[0143] (Third liquid phase → fourth liquid phase) The tertiary liquid phase was transferred to another processing vessel, which was set up as follows to process the material and obtain "sodium chloride" and "sodium sulfate." Meanwhile, the remaining tertiary liquid phase was extracted and separated to obtain the quaternary liquid phase of the organic phase and the quaternary liquid phase of the inorganic phase. The quaternary liquid phase of the organic phase was then transferred to another processing vessel for the next step. The following conditions were used to process the materials, yielding "sodium chloride" and "sodium sulfate". Carbon dioxide flow rate: 1780 mL / min Processing kettle rotation speed: 60 r / min Extraction solvent: Extractant: Trioctylmethylammonium salt; Diluent: Positive hexanol Add the organic phase and inorganic phase so that the volume ratio is approximately 1:2.11. Reaction temperature: 25°C Processing vessel internal pressure: 1.8 MPa Solubility of carbon dioxide: 0.07 mol / L Continue the process under the above conditions until the pH reaches 3.

[0144] The fourth liquid phase of the inorganic phase described above was taken from the bottom of the processing vessel and sent to a self-steam mechanical compressor (MVR) apparatus. In this apparatus, it was heated to 100°C, and the compressor was operated to supersaturate the sodium sulfate to obtain "sodium sulfate" and "mother liquor".

[0145] As described above, once the sodium sulfate concentration in the mother liquor was reduced to 5% by the extraction of sodium sulfate, the temperature was lowered to 50°C, and the mother liquor was sent to another self-vapor mechanical compression (MVR) apparatus. In this apparatus, the compressor was operated to concentrate and supersaturate the mixture to obtain sodium chloride. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0146] (Fourth liquid phase of the organic phase → inorganic liquid phase / organic liquid phase) The following conditions were used to obtain "ammonium chloride". The above-mentioned "aqueous ammonia solution" was added to the fourth liquid phase of the organic phase so that the volume ratio of organic phase to inorganic phase was approximately 1:0.49. Back-extraction and separation treatment was performed on the fourth liquid phase of the organic phase after the addition of an aqueous ammonia solution, with the treatment vessel rotation speed set to 50 r / min. The inorganic liquid phase separated above was concentrated and evaporated to obtain ammonium chloride, while the organic liquid phase was returned to the tertiary liquid phase. The water evaporated here was reused as treated water after distillation, rendering it harmless.

[0147] The wastewater treated by the gas phase in Example 4 was as follows. All obtained general chemical raw materials (excluding ammonia water) had a purity of 90% or higher, and the entire amount of high-ammonia nitrogen salt aqueous solution was treated. Aluminum hydroxide 1.20 t Sodium bicarbonate 1.90 t Ammonium chloride 0.07 t Sodium chloride 0.70 t Sodium sulfate 1.10 t Ammonia solution 0.30 t (concentration range 5-15%)

[0148] -Solid-phase treatment process (Figures 3-7)- (First washing process: Figures 3, 4, and 7) Meanwhile, the secondary aluminum dross is reacted with water to separate the gas-liquid phase from the solid phase, and the solid phase is sent to the first processing vessel. At this time, the water content of the solid phase was 22%. In the first processing vessel, the treated water from the washing water treatment (1) and (2) was added as washing water in a mass ratio of 6 to the solid phase 1, and the liquid level in the first processing vessel was raised to 70%. The rotation speed of the stirring blade 5 was controlled to 65 r / min. In addition, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Carbon dioxide was supplied to the processing vessel, and the pH was adjusted to 6.2. After the pH reached 6.2, acetic acid and oxalic acid were added as adjusting agents to adjust the pH to 4.2. The solution was adjusted to pH 4.2 and then washed for 20 minutes. During the 20-minute washing time, chloride ions (Cl - A tracer ion was selected, and samples were taken at 6-minute intervals to examine the tracer ion content. The chloride ion content was adjusted to pH 4.2 and washed repeatedly between two consecutive samplings until it fell below 10%. The first washing process was terminated when the chloride ion content fell below 10%.

[0149] (Second cleaning process: Figures 3, 5, and 7) The slurry sent from the first processing vessel was subjected to solid-liquid separation. The solid phase was sent to the second processing vessel, and the liquid phase was sent to the washing water treatment (1). The solid phase and the treated water from the washing water treatment (3) are injected into the second treatment vessel as washing water, and the liquid level in the second treatment vessel is raised to 70%. The rotation speed of the stirring blade 5 was controlled to 65 r / min. The frequency of the ultrasonic stirrer 4 was also controlled to 40 kHz. Acetic acid and oxalic acid were added as adjusting agents to adjust the pH to 3.2. The solution was adjusted to pH 3.2 and then washed for 28 minutes. During the 28-minute washing time, chloride ions (Cl - ) was selected as the tracer ion, and samples were taken at 8-minute intervals to examine the tracer ion content. Washing was repeated until the change in the chloride ion content became less than 10% between two consecutive samplings where the change was continuous, and after adjusting the pH to 3.2. When it became less than 10%, the secondary washing treatment was terminated.

[0150] (Tertiary washing treatment Figures 3, 6, 7)- The slurry sent from the second treatment kettle was subjected to solid-liquid separation. The solid phase was sent to the third treatment kettle, and the liquid phase was sent to the washing water treatment (2), respectively. The solid phase and fresh water were injected into the third treatment kettle as washing water, and the liquid level height in the third treatment kettle was set to 70%. The rotation speed of the stirring blade 5 was controlled to 55 r / min. Also, the frequency of the ultrasonic stirrer 4 was controlled to 40 kHz. Calcium carbide slag was added as an adjusting agent to adjust the pH to 10. Washing was performed for 25 minutes after adjusting the pH to 10. During the 25-minute washing time, chloride ions (Cl - ) were selected as tracer ions, sampled at 6-minute intervals, and the content of the tracer ions was inspected. Washing was repeated after adjusting the pH to 10 until the change in the chloride ion content became less than 10% between two consecutive samplings where the change was continuous. When it became less than 10%, the next treatment was performed. For the next treatment, that is, for the slurry in the third treatment kettle, solid-liquid separation was performed. The liquid phase after solid-liquid separation was sent to the washing water treatment (3), and the treated water treated in the washing water treatment (3) was reused as the washing water for the secondary washing treatment. On the other hand, the solid phase after the above solid-liquid separation was inspected for the content of heavy metals and impurity ions by a specified inspection method. If it met the specified standards, the treatment was terminated. If it did not meet the standards, it was returned to the washing after the first solid-liquid separation in the tertiary washing treatment (the solid phase was returned), and the subsequent treatments were repeated.

[0151] (Application of the detoxified solid phase to concrete materials) The solid phase that met the specified standards could be discarded as general waste, but in this example, it was reused as a cement admixture for concrete. The solid phase water content (mass fraction) after solid-liquid separation was 24%. This water-containing solid-liquid mixture (slurry) is diluted with water to a slurry content (by mass) of 24%, and 0.002% cellulose ether is added as an auxiliary material to stabilize the mud and prevent the solid phase in the mud suspension from settling. The aforementioned auxiliary material was added to the cement material of the concrete at a mass ratio of 22% (wet basis).

[0152] Thus, with the present invention, by reacting secondary aluminum dross with water, hydrogen and other general industrial materials can be obtained from the gas-liquid phase, the solid phase can be rendered harmless to obtain general industrial materials such as cement material for concrete, and the water (liquid phase) used in each process can also be rendered harmless and made into a state where it can be disposed of (wastewater) or reused. [Explanation of symbols]

[0153] 3 Pot body 4. Ultrasonic stirrer 5. Agitation blades 11 Annular air supply pipe 13 Water-cooled heated jacket

Claims

[Claim 1] A method for detoxifying secondary aluminum dross, which is the residue of primary aluminum dross used to recover metallic aluminum or aluminum alloys in aluminum dross, and for the detoxification and reuse of the secondary aluminum dross generated and used in this detoxification process, A process for classifying the solid phase component of secondary aluminum dross to a predetermined particle size. A process in which secondary aluminum dross of a predetermined particle size is mixed with water, and the inside of the processing vessel is purged with nitrogen to deoxidize it. The process involves adding secondary aluminum dross of a predetermined particle size and water to the aforementioned processing vessel, and then stirring, mixing, and reacting the mixture. A process in which cooling or heating is performed during the reaction according to the temperature inside the processing vessel, A reaction process that carries out the following: A gas-liquid phase treatment step is performed to obtain hydrogen and a plurality of compounds from the gas-liquid phase of a slurry of secondary aluminum dross of a predetermined particle size and water after the reaction treatment step. A solid phase treatment step is performed to obtain an industrial solid phase material from the solid phase of a slurry of secondary aluminum dross of a predetermined particle size and water after the reaction treatment step, in which the solid phase has been rendered harmless. It is equipped with, and furthermore, The liquid phase used or generated in the aforementioned gas-liquid phase treatment step and the aforementioned solid phase treatment step is rendered harmless and reused in the aforementioned reaction treatment step, the gas-liquid phase treatment step, and the aforementioned solid phase treatment step. Methods for sorting and reusing secondary aluminum dross.

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