JP3394720B2 - Simultaneous treatment of alumid ash and papermaking sludge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inevitably involves a basic and essential melting step of aluminum raw materials in manufacturing a wide variety of products made of aluminum (hereinafter abbreviated as "aluminum") or aluminum alloys. The aluminum dross residual ash that is generated and the papermaking sludge that is inevitably generated from the papermaking process that manufactures paper, using their respective physical properties,
At the same time, an alumina composition that can be easily and economically processed to effectively remove harmful impurities that are problematic in terms of environmental use or resource utilization and to be industrially useful resources The present invention relates to a method for simultaneously treating aluminum dross residual ash and papermaking sludge that can be collected as.

[0002]

2. Description of the Related Art Aluminum products made of aluminum or aluminum alloys have excellent properties in touch resistance, light weight, electrical conductivity, and heat conductivity, and are therefore used in vehicles, ships, machinery, electricity, construction, daily necessities, food and drink. It is used in an extremely large number of fields such as containers, and its usage forms are extremely diverse as ingots, rolled products, extruded products, forged products and processed products thereof.

In order to manufacture such an aluminum product, an aluminum melting step of melting an aluminum raw material is indispensable as a basic step regardless of the usage form.

In the aluminum melting step, the surface of the molten metal is always oxidized because aluminum or aluminum alloy is a metal that is easily oxidized.
Usually flux is used. However, it is difficult to completely prevent the surface of the molten metal from being oxidized in the aluminum melting step, and so-called aluminum dross containing aluminum oxide as a main component is inevitably generated on the surface of the molten metal.

Since this aluminum dross usually contains 80% by weight of aluminum, the aluminum dross, which has been scraped from the surface of the molten metal and solidified, is melted again, and a squeezing machine such as a rotary blade is used. Molten metallic aluminum is physically squeezed out and collected under high temperature and pressure, and if necessary, this operation is repeated a plurality of times to collect metallic aluminum as much as possible.

[0006] The residue after the metal aluminum is recovered from the aluminum dross as much as possible, that is, the aluminum dross residual ash mainly consists of aluminum oxide (alumina), but the metal aluminum (alloy also remains). In addition, it also contains aluminum nitride (AlN) which reacts with water to generate ammonia, which is an environmental problem.

The aluminum nitride contained in the aluminum dross residual ash usually reaches 5 to 20% by weight, and reacts with moisture in the air to generate ammonia even when left standing or stored, which is safe and environmentally friendly. In addition, the above problems are caused, and in a neutral or reducing atmosphere, it is fairly stable even at high temperatures, and it is an obstacle to the utilization of useful resources such as chemical industrial raw materials, ceramic raw materials, and alumina slag forming agents for metal refining. Has become.

Therefore, regarding aluminum dross residual ash,
So far, oxidative decomposition of the main harmful impurities aluminum nitride, in addition to performing pollution-free treatment by oxidation of dangerous fine-grained metal aluminum, or have been variously studied to reuse as an alumina source, As a method thereof, a hydrothermal treatment method and a high temperature calcination method have been known for a long time.

In the classical hydrothermal treatment method, a large amount of water, sometimes seawater, is added to aluminum dross residual ash, and the mixture is stirred while heating in an open container to react AlN + 3H ₂ O → Al (OH) ₃ + NH ₃ However, since a huge reaction tank is used, the burden of equipment costs and location conditions is large, the processing takes a long time, and the effect of removing aluminum nitride is not always sufficient. Therefore, it is essential to collect and dispose of ammonia, which complicates equipment and operations.

Further, in the high temperature calcination method, the aluminum dross residual ash is heated to more than red heat in an oxidizing atmosphere to oxidize and decompose aluminum nitride into alumina (Al ₂ O ₃ ). In order to decompose aluminum nitride containing up to 20% by weight to 90% by weight or more and reduce the amount of aluminum nitride in the product to 1% by weight or less,
A high temperature of up to 1300 ° C. is required, and there is a problem in that the cost of the equipment and energy increase.

By the way, in the conventional simple oxidation firing method,
The decomposition of aluminum nitride is mainly carried out by the following reaction 2AlN + 3O ₂ → Al ₂ O ₃ + N ₂ , and aluminum nitride becomes alumina. If water is present in the course of this reaction, the following hydration reaction AlN + 3H ₂ O → Al (OH) ₃ + NH ₃ has the effect of promoting the decomposition of aluminum nitride.
The aluminum hydroxide generated thereby becomes alumina by the following dehydration reaction 2Al (OH) ₃ → Al ₂ O ₃ + 3H ₂ O during heating, and the water generated at that time promotes decomposition of aluminum nitride again. Exert a synergistic effect.

For this reason, conventionally, a method of adding aluminum hydroxide to the aluminum dross residual ash and baking it (Japanese Patent Laid-Open No. 8-192127) or a method of adding water to the aluminum dross residual ash and baking it ( Japanese Patent Publication No. 7-32901) has been proposed, but the former has a problem in economically obtaining aluminum hydroxide, which is not common, and the latter is usually hydrothermally treated. For example, the reaction does not proceed slowly at 100 ° C or lower so that it takes 4 to 7 days to decompose 80% by weight of aluminum nitride, and further, during the red hot firing, the adhered or added water vaporizes almost instantly. The effect is only slight as it will be lost.

On the other hand, paper obtained mainly by making vegetable filaments has been used as a means of recording and information transmission since ancient times, and in recent years, the fields of packaging, structures and household paper have been added, which has a negative impact on human life. It is considered essential, and its usage is increasing year by year.

Such paper is usually produced by virgin pulp produced in the pulping process of plant fiber raw materials such as wood, waste paper pulp made of waste paper itself, or a deinking process using waste paper as a raw material. DIP (deinking pulp) is used as a raw material, and is usually a beating step, a dissociation step, a sizing step, a filling step that includes various operations such as a filling step, a paper making step for making paper using a paper machine, a rewinder. It is manufactured through a finishing process including operations such as cutting, cutting, and coating operations. In each of these steps, various chemicals are added, paint is applied, and surface treatment is performed. Then, a paper suitable for a predetermined application is manufactured on a large scale.

[0015] However, in the factory wastewater generated in the papermaking process including these pulping process, deinking process, preparation process, papermaking process, finishing process, etc., soluble substances eluted from raw materials such as wood, pulp and waste paper , Fine fibers that cannot withstand papermaking, foreign substances contained in waste paper that are discharged during the deinking process, non-fibrous substances such as ink, paper paint, paper filler, etc., and washing water discharged from the papermaking process. Various insoluble solids such as suspended solids are contained, and so-called papermaking sludge is inevitably generated in order to remove these insoluble solids by solid-liquid separation from the viewpoint of environmental protection.

That is, in the wastewater treatment of the factory wastewater generated in this papermaking process, first, the factory wastewater is chemically treated, and then it is settled and separated in the coagulation sedimentation tank, and the supernatant liquid is extracted from the upper part and the bottom part thereof. The papermaking sludge slurry, which has been densified to a solid concentration of about 5% by weight, is extracted, and the papermaking sludge slurry is pressure-filtered to recover wet papermaking sludge, and the papermaking sludge slurry is pressure-filtered. The filtrate recovered in (1) is combined with the supernatant of the previous flocculation settling tank, and if necessary, it is subjected to chemical treatment again and then discharged.

The papermaking sludge recovered by the wastewater treatment in this papermaking process is usually in the form of a cake containing 50% by weight or more of water, and its solid content composition is a small amount of long fibers, a large amount of fine fibers, and a fine inorganic substance ( (Usually clay) and trace amounts of adhering water-soluble components attached. For this reason, it is difficult to solidify the papermaking sludge structurally as it is, and since it is decomposed by microorganisms, simple disposal such as landfill is extremely difficult.

Therefore, in the past, attempts have been made to make papermaking sludge a useful resource, for example, by using it as a building material board, a component of plant culture soil, or the like. Most of the papermaking sludge is incinerated at present, and ash obtained by burning and removing organic matter [so-called PS ash; usually SiO 2
₂ : 40 to 45% by weight, Al ₂ O ₃ : 25 to 35% by weight, Igros: 5 to 8% by weight, which is an inorganic substance (clay content), is merely used as a soil modifier. Absent.

However, the papermaking sludge has a large amount of attached moisture even though its oxidation reaction is an exothermic reaction in terms of energy, so that it is in a red-hot state under economical conditions in consideration of fuel cost and furnace material. It is difficult to completely oxidize and decompose PS, and PS ash contains some organic matter as is clear from the loss on ignition. Therefore, although the composition of PS ash obtained by incineration of papermaking sludge is almost the same as that of soil, there are some things that lead to an image deterioration such as a visually unpleasant color, sometimes a bad odor, and coloring of elution water. Therefore, there is still room for improvement as a product.

[0020]

Therefore, the present inventors efficiently and economically treat aluminum dross residual ash and papermaking sludge, which are inevitably generated in industrial activities and have a problem in recycling useful resources. As a result of earnestly studying a method that is environmentally friendly and can be made into a useful resource, aluminum nitride in aluminum dross residual ash is decomposed by water vapor present at 150 ° C. or higher during heating during firing. Focusing on the fact that the papermaking sludge contains water that is released at high temperatures in addition to simple adhered water, and by combining the characteristics of both, it is more effective than a simple conventional firing method. It was found that aluminum nitride can be decomposed at low temperature as much as possible, and the organic matter of papermaking sludge can be completely burned off to obtain an alumina composition that can be recycled as a useful resource. Thus, the present invention has been completed.

Therefore, the object of the present invention is to efficiently and simultaneously treat the aluminum dross residual ash and the papermaking sludge, both of which are problematic in terms of treatment or utilization of useful resources, and efficiently. Another object of the present invention is to provide a simultaneous treatment method of aluminum dross residual ash and papermaking sludge, which can be recovered as an industrially useful alumina composition by removing harmful impurities as much as possible.

Another object of the present invention is to decompose aluminum nitride at a lower temperature as much as possible and to completely combust organic matters in papermaking sludge as compared with a simple conventional firing method. Another object of the present invention is to provide a simultaneous treatment method for aluminum dross residual ash and papermaking sludge, which can be used as a component of an alumina composition while at the same time making an inorganic substance (corresponding to ash content) a useful resource.

[0023]

[Means for Solving the Problems] That is, the present invention provides an aluminum dross residue after recovering metallic aluminum or aluminum alloy from aluminum dross generated in an aluminum melting step of melting an aluminum raw material made of aluminum or an aluminum alloy. This is a simultaneous treatment method of aluminum dross residual ash and papermaking sludge, which comprises mixing ash and papermaking sludge collected by solid-liquid separation of sludge generated in wastewater treatment in the papermaking process, and firing the resulting mixture.

In the present invention, the aluminum dross residual ash to be simultaneously treated is, if it is by-produced from the melting step of melting the raw material made of aluminum or aluminum alloy,
It is not particularly limited and is usually an anhydrous powdery substance having a size of 250 μm or less, and its composition is generally metallic aluminum (Al).
8-15% by weight, aluminum oxide (Al ₂ O ₃ ) 50-60
% By weight, aluminum nitride (AlN) 5-20% by weight, iron content (as Fe) 0.5-2% by weight, silicon content (as Si) 0.5-10% by weight, magnesium content (as Mg) 0.6 .About.6% by weight, and contains some flux-derived alkali and Cl and F.

The aluminum dross residual ash usually contains an alkali metal derived from the flux, and an alkaline component (Na ₂ ) is contained in a calcined product (alumina composition) obtained by mixing with papermaking sludge and calcining at the same time. The total of O and K ₂ O) may be contained in the range of about 1 to 2% by weight. Therefore, when this alkali content becomes a problem due to the use of the alumina composition obtained by firing, it is preferable to wash the aluminum dross residual ash with water or a weakly acidic aqueous solution prior to mixing with the papermaking sludge. Soluble salts in the residual ash should be removed by dissolution. By this washing with water, the alkali content can be removed by 50 to 60% by weight, and the alkali content can be removed by about 70 to 80% by weight with a slightly acidic aqueous solution having a pH of about 4.
As a result, the alkali content in the alumina composition can be reduced to 1% by weight or less.

Similarly, the papermaking sludge to be simultaneously treated in the present invention may be any sludge generated in the wastewater treatment of the papermaking process, such as pulping step, deinking step, preparation step. It is not limited by the treating method and operating method in the forming step, the paper making step, the finishing step, etc., and the additives and chemicals used, and examples thereof include a chemical treating method for plant fiber raw materials such as wood, paper, or It is not particularly limited by the type of paper product, the added filler material, the sizing agent and the like.

This paper-making sludge is a soluble substance derived from raw materials such as wood, pulp, and waste paper, fine fibers that cannot withstand papermaking,
It contains various insoluble solids such as foreign matters derived from used paper, inks, paints for paper, non-fibrous substances such as fillers in paper, floating substances derived from the paper making process, and 50% by weight or more of attached moisture, and preferably The attached water content is 50 to 70% by weight. As an example of the composition, the solid content is 35 to 45% by weight, the attached water content is 55 to 65% by weight, and the composition of the solid content is carbon (C;
25-30% by weight of organic substances and vegetable fibers, SiO
₂ (from clay) 15 to 20% by weight and Al ₂ O
₃ (from clay) is 10 to 15% by weight, and the oxidative burning loss (burning loss and water of crystallization of inorganic substances) is about 40% by weight.

Further, this papermaking sludge contains water that cannot be removed by ordinary drying due to its structure and physical adsorption action, and as shown in the thermal decomposition test result shown in FIG. With the above, water is gradually released,
It releases a large amount of water at 250 to 400 ° C. In the present invention, it is considered that the properties of the papermaking sludge, in combination with the thermal decomposition properties of aluminum nitride, accelerate the reaction of rapidly decomposing the aluminum nitride into alumina.

In the present invention, the aluminum dross residual ash and the papermaking sludge are mixed before firing.
When alumidoross residual ash and papermaking sludge are mixed, lumps of papermaking sludge are easily generated.Therefore, in order to ensure uniform mixing and appropriate fluidity, the type of mixer and insertion method into the firing furnace If necessary, water may be added according to the circumstances.

The mixing ratio of the aluminum dross residual ash and the papermaking sludge varies depending on the amount of water adhering to the papermaking sludge, but it promotes the decomposition of aluminum nitride in the aluminum dross residual ash to leave it as much as possible. From the viewpoint of reducing the amount, the amount is preferably 10 to 100 parts by weight, more preferably 20 to 70 parts by weight, relative to 100 parts by weight of aluminum dross residual ash. If the mixing ratio of the papermaking sludge is too small, the effect of promoting the decomposition of aluminum nitride in the aluminum dross residual ash is not always sufficient, and even if it is too large, the decomposition of aluminum nitride is inhibited, and in the alumina composition obtained by firing. Undesirably increases the aluminum nitride content.

Although the detailed reaction mechanism is still unknown, if the above mixing ratio is appropriate, water vapor generated from the papermaking sludge during the heating process of the mixture obtained by mixing the two is The decomposition of aluminum nitride in dross residual ash is remarkably promoted, but if the mixing ratio of papermaking sludge becomes too large, the carbon content in the mixture increases and the atmosphere around each particle in aluminum dross residual ash becomes temporary. It is considered that it becomes reductive and hinders the oxidative decomposition of aluminum nitride.

The aluminum dross residual ash and the papermaking sludge can be mixed by mixing the both uniformly, and can be carried out by an arbitrary method such as a screw type, paddle type or raid type. When a lump of the mixture is generated during the mixing operation, it is preferable to lump the mixture into an appropriate size, for example, a size of 20 mmφ or less, and then calcine.

For the firing of the mixture of the aluminum dross residual ash and the papermaking sludge thus obtained, any firing furnace can be used as long as it can be oxidized, but preferably a fuel oil combustion type or gas combustion type is used. An internal heat countercurrent combustion rotary type firing furnace is convenient. When such a rotary type firing furnace is used, for example, the mixture is inserted from the above mixer by allowing it to fall naturally into the firing furnace through a water-cooled jacket type insertion tube having an inner diameter of 50 to 200 mm and the mixture in the furnace. You may make it crush naturally. If the inner diameter of the water-cooled jacket type insertion cylinder is too thin, it will be difficult to pass the mixture through the insertion cylinder due to an increase in pressure, and if it is too thick, it will be difficult to break the mixture.

Regarding the firing conditions for the mixture of aluminum dross residual ash and papermaking sludge, the firing temperature is usually 850 to 11
00 ° C, preferably 900 to 1000 ° C, and the rate of temperature rise is usually 10 to 30 ° C / min, preferably 15 to 25 ° C /
Minutes. If the firing temperature is lower than 900 ° C, there is a problem that the decomposition and removal of aluminum nitride and organic substances are insufficient.
On the contrary, if the temperature is higher than 1100 ° C., the effect is saturated, energy is wasted, and the maintenance cost of refractory bricks is increased. Even when the content of aluminum nitride in the alumina composition of the fired product is set to, for example, 0.5% by weight or less, the firing temperature up to 1100 ° C. is sufficient, and a high temperature of 1000 ° C. or higher is substantially unnecessary. Also,
Regarding the rate of temperature increase, if the temperature is slower than 10 ° C / min, the aluminum nitride decomposition promoting effect is actually saturated, and there is a problem that the equipment becomes unnecessarily long. Not only that, the decomposition of aluminum nitride becomes insufficient. In the present invention, in practice, in the case of a rotary firing furnace, 30 to 50 after the mixture is inserted.
The exit firing temperature may reach 900 to 1100 ° C. in minutes, and the material may stay for 10 to 15 minutes after reaching the maximum temperature.

After the firing is completed, the obtained fired product is cooled by an appropriate method and recovered as an alumina composition. The method for cooling the fired product is not particularly limited, and for example, a water-cooling type or air-cooling type rotary cooler may be used. Further, depending on the properties of the fired product, a fluidized bed cooler convenient for utilizing waste heat It is also possible to transfer to a heat resistant container and allow to cool naturally.

By the way, in the continuous firing of aluminum dross residual ash, when the particle size is approximately 250 μm or less, 50 μm
The following particles are contained in an amount of about 10 to 60% by weight, inevitably generate a large amount of dust, and the particle size of the generated inorganic oxide is also the particle size of the papermaking filler during the baking of the papermaking sludge. Dust is unavoidably generated with a diameter (10 μm or less), and it is not easy to collect these dusts.

However, in the present invention, since the aluminum dross residual ash and the papermaking sludge are wet mixed,
Dust (mixture of fired product powder and unfired product powder) generated in the process of firing this mixture and cooling the produced fired product is wet-collected and introduced into the process of mixing aluminum dross residual ash and papermaking sludge By doing so, the dust generated in the firing step of the mixture and the cooling step of the fired material can be recovered at a rate of almost 100%. When the dust is collected by a wet method, the amount of water used is such that it is convenient for transfer and does not become excessive in the mixing process.

According to the method of the present invention, the aluminum dross residual ash can be treated at a lower temperature by combining the thermal decomposition characteristics of the aluminum nitride in the aluminum dross residual ash with the moisture release characteristics of the papermaking sludge. Aluminum nitride can be decomposed as much as possible, whereby it can be recovered as an alumina composition that can be converted into a useful resource.

In addition, since the papermaking sludge is also dispersed in the aluminum dross residual ash, it is sufficiently oxidized, no unburned carbon compound remains in the fired product, and no bad odor is generated. Inorganic substances derived from the fillers in paper existing in the sludge can also be made into useful resources as one component of the alumina composition.

Further, when the aluminum dross residual ash was singly burned, clinker was liable to be generated during the calcination, and sometimes the calcination operation was inconvenient, but in the case of the present invention, Such clinker generation is suppressed,
Safe and smooth firing work can be performed. this is,
It is considered that the baking temperature is relatively low and the steam generated from the papermaking sludge efficiently removes not only aluminum nitride but also other alkali compounds which are factors of the fusible or caking compound.

The alumina composition obtained by the method of the present invention contains alumina as a main component, contains 1% by weight or less of aluminum nitride and 0.5% by weight or less of metallic aluminum, does not contain an organic substance causing a bad odor, and contains alumina. Content is usually 70% by weight
The above can be made into useful resources.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below based on test examples, comparative test examples, examples, and comparative examples.

Test Example 1 Metal aluminum: 5.9% by weight, AlN: 14.5% by weight,
Al ₂ O ₃ : 57.0 wt%, Si (as SiO ₂ ):
Aluminum dross residual ash having a composition of 3.5% by weight (particle size 1
25 μm or less) 75 g, Al ₂ O ₃ : 13.7 wt%, SiO ₂ : 17.5 wt%, carbon content (C): 27.
Papermaking sludge with a dry matter composition of 8% by weight (moisture 60
%), And the resulting mixture is 75 mmφ
It was put in a crucible of No. 1 and fired at a predetermined firing temperature using a non-enclosed electric furnace. The relationship between the firing temperature and the content of aluminum nitride in the fired product (alumina composition) at this time is shown in FIG.

Comparative Test Example 1 The same procedure as in Test Example 1 was carried out except that only the residual ash of almidros was used, and the test was carried out at a predetermined baking temperature, and the relationship between the baking temperature and the content of aluminum nitride in the baked product was investigated. It was The results are shown in Figure 2.

As is clear from the results shown in FIG. 2, when aluminum dross residual ash is burned at the same time as the papermaking sludge, harmful aluminum nitride is approximately 300 ° C. or more as compared with the case where it is burned alone. Was also found to decompose at low temperatures. The content of metallic aluminum in the obtained fired product was
Except when the aluminum nitride content was 1% by weight or more, all were 0.3% by weight or less.

Test Example 2 The aluminum dross residual ash used in Test Example 1 and the papermaking sludge were mixed in various proportions, and the same procedure as in Test Example 1 was repeated.
Then, the relationship between the mixing ratio of the aluminum dross residual ash and the papermaking sludge and the aluminum nitride content in the fired product (alumina composition) was investigated. The results are shown in Fig. 3.

As is clear from the results shown in FIG.
Mixing papermaking sludge with 100 parts by weight of residual residual ash
When the ratio is 10 to 100 parts by weight, a remarkable mixing effect is exhibited,
The content of aluminum nitride in the fired product decreased to less than 1% by weight.
It was Especially when the mixing ratio of papermaking sludge is 20 to 70 parts by weight.
Has an aluminum nitride content of less than 0.5% by weight
It was The alumina content in the fired product is the aluminum dross.
Mixing ratio of papermaking sludge to 100 parts by weight of residual ash is 1
If 1 part by weight is 77.0% by weight, if 25 parts by weight
75.2 weight% in total, 73.2 weight in case of 43 weight parts
%, And in the case of 67 parts by weight, 71.4% by weight.
It was This is the ash composition in the papermaking sludge [Al ₂O₃/
(Al₂O₃+ SiO₂) = 44% by weight]
Is.

Comparative Test Example 2 Solid content of 60% by weight was obtained by adding only water to the almidross residual ash.
After that, it was fired in the same manner as in Test Example 2. Result is,
2.0% by weight when the content of aluminum nitride is 1.8% by weight and only aluminum dross residual ash is fired alone (mixing ratio of papermaking sludge to 100 parts by weight of aluminum dross residual ash in FIG. 3 is 0 parts by weight). Although a slight effect of accelerating the decomposition of aluminum nitride was observed as compared with Example 1, it cannot be said that a special effect was exhibited as compared with the case of mixing papermaking sludge.

Example 1 Using aluminum dross residual ash and papermaking sludge shown in Table 1,
These aluminum dross residual ash, papermaking sludge and water were continuously charged into a screw type continuous mixer at a ratio of 75 parts by weight of aluminum dross residual ash, 25 parts by weight of papermaking sludge and 70 parts by weight of water, respectively, and the mixture was mixed. The mixture is continuously mixed with a machine for a residence time of 2 minutes, and the mixture discharged from the outlet of the mixer is directly charged into a rotary kiln having a length of 15 m and a diameter of 1.2 mφ (the firing temperature at the inlet is room temperature), and the firing temperature at the outlet is set. 1
Firing under conditions of 000 to 1050 ° C. and residence time of 1 hour,
The calcined product was collected from the outlet of the rotary kiln and cooled using a water-cooled rotary chiller to obtain an alumina composition of the calcined product.

[0050]

[Table 1]

The dust generated during the firing of the mixture and the cooling of the fired material is sprayed or sprayed with water and wet-collected,
It was introduced into a screw type continuous mixer and returned to the mixture together with aluminum dross residual ash and papermaking sludge. At this time, the water content in the mixture was adjusted to always maintain 50% by weight. The composition of the obtained alumina composition was examined, and the presence or absence of an offensive odor after being moistened with water was examined. The results are shown in Table 2.

Example 2 The aluminum dross residual ash used in Example 1 and water were introduced into a washing tank at a solid concentration of 200 g / liter, and washed in this washing tank for a residence time of 3 minutes, and then for a residence time. The washed aluminum dross residual ash having a solid concentration of 50 wt% was extracted from the bottom of the sedimentation tank for 10 minutes, and the washed aluminum dross residual ash thus obtained was used to produce paper sludge in the same manner as in Example 1 above. Simultaneous treatment was performed to obtain an alumina composition of a fired product. Regarding the obtained alumina composition,
The composition was examined and the presence or absence of an offensive odor after moistening with water was examined. The results are shown in Table 2.

Comparative Example 1 Using only the aluminum dross residual ash used in Example 1, firing was performed under the same conditions as in Example 1 to recover a fired product, and an alumina composition of the fired product was obtained. The composition of the obtained alumina composition was examined, and the presence or absence of an offensive odor after being moistened with water was examined. The results are shown in Table 2.

Comparative Example 2 A calcined product obtained by calcining only papermaking sludge (papermaking sludge incineration ash) was recovered from the calcining furnace of a paper mill in operation, Koyo Paper Co., Ltd., and calcined. The composition of the product was examined, and the presence or absence of an offensive odor after moistening with water was examined. The results are shown in Table 2.

[0055]

[Table 2]

As is clear from the results shown in Table 2, by mixing the aluminum dross residual ash with the papermaking sludge, the decomposition of aluminum nitride is promoted, and the alumina composition to be obtained is also problematic in alkali and chlorine. Is also removed, and most of the organic substances in the papermaking sludge are also removed to obtain a white odorless, good quality resourceable product.

[0057]

According to the present invention, the aluminum dross residual ash and the papermaking sludge, both of which have problems in terms of treatment or utilization of useful resources, can be efficiently treated at the same time in terms of resources and equipment. , Harmful impurities can be removed as much as possible and can be recovered as an industrially useful alumina composition, and aluminum nitride can be decomposed as much as possible at a lower temperature than the conventional firing method, Moreover, the organic matter in the papermaking sludge can be completely burned and the inorganic matter (ash content) can be made into a useful resource as one component of the alumina composition.

[Brief description of drawings]

FIG. 1 is a graph showing the thermal decomposition characteristics of a 105 ° C. dried product of an example papermaking sludge.

FIG. 2 is a graph showing the relationship between the firing temperature and the content of aluminum nitride in the fired product when firing the mixture of the aluminum dross residual ash and the papermaking sludge alone and the aluminum dross residual ash. is there.

FIG. 3 is a graph showing the relationship between the mixing ratio of aluminum dross residual ash and papermaking sludge and the content of aluminum nitride in the fired product.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaharu Sugiyama Inventor Masaharu Sugiyama 1-34-1, Kambara, Kambara-cho, Anbara-gun, Shizuoka Nippon Light Metal Co., Ltd. Group Technology Center (72) Noboru Sugiyama Kambara-cho, Anbara-gun, Shizuoka 1-34-1 Nippon Light Metal Co., Ltd. within the group technology center (72) Inventor Hiroshi Watanabe 1-34 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Nihon Light Metal Co., Ltd. within the group technology center (72) Inventor Nanba Masatoshi, Tokyo 2-22 Higashishinagawa, Shinagawa-ku, Nihon Light Metal Co., Ltd. (72) Inventor Katsutoshi Kawano 165-1 Hinode-cho, Fuji City, Shizuoka Prefecture Sunmic Shizuoka Building Sanmic Chiyoda Stock Company In-house (72) Inventor Shigeru Ohkune 165-1 Hinodecho, Fuji City, Shizuoka Prefecture Sunmic Shizuoka Building Sanmic Chiyoda Stock Company In-house (7 2) Inventor Shigeo Nakamura 450 Hina, Fuji City, Shizuoka Prefecture Koyo Paper Manufacturing Co., Ltd. Technical Department (56) References JP-A-63-302932 (JP, A) JP-A-9-310129 (JP, A) JP Japanese Unexamined Patent Publication No. 6-135761 (JP, A) Japanese Unexamined Patent Publication No. 51-114219 (JP, A) Japanese Unexamined Patent Publication No. 8-192127 (JP, A) Japanese Unexamined Patent Publication No. 9-176752 (JP, A) Japanese Unexamined Patent Publication No. 63-291678 (JP , A) Japanese Patent Publication Sho 7-32901 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B09B 3/00-5/00 C22B ^7/ 00-7/04 C22B 21/00 -21/06 C02F 11/00

Claims (6)

(57) [Claims] 1. The aluminum dross residual ash after recovering metallic aluminum or aluminum alloy from the aluminum dross generated in the aluminum melting step of melting an aluminum raw material made of aluminum or an aluminum alloy, and the wastewater treatment in the papermaking process. A method for simultaneous treatment of aluminum dross residual ash and papermaking sludge, which comprises mixing the obtained sludge with a papermaking sludge that is separated by solid-liquid separation and firing the resulting mixture. 2. The residual amidross ash is washed with water or a weakly acidic aqueous solution prior to mixing with the papermaking sludge.
Simultaneous treatment of aluminum dross residual ash and papermaking sludge described in. 3. The papermaking sludge has a water content of 50 to 50.
The simultaneous treatment method of aluminum dross residual ash and papermaking sludge according to claim 1 or 2, which is 70% by weight. 4. The aluminum dross according to claim 1, wherein the mixing ratio of the almidross residual ash and the papermaking sludge is 10 to 100 parts by weight of the papermaking sludge with respect to 100 parts by weight of the aluminum dross residual ash. Simultaneous treatment of residual ash and papermaking sludge. 5. The firing temperature of the mixture of the almidross residual ash and the papermaking sludge is 900 to 1100 ° C.
4. The method for simultaneously treating the aluminum dross residual ash according to any one of 4 and the papermaking sludge. 6. The dust collected in the step of firing the mixture and cooling the fired product is wet-collected, and the dust collected in the wet is introduced into the step of mixing the aluminum dross residual ash and the papermaking sludge. The method for simultaneously treating the aluminum dross residual ash according to any one of 1 to 5 and the papermaking sludge.