JPH093671A - Washing method for tool for working aluminum material - Google Patents

Abstract

PURPOSE: To provide an aluminum washing method which separates and removes impurities out of an aged washing liquid, recovers sodium hydroxide and aluminum components of valuable matter and allows the reutilizing of the recovered sodium hydroxide again as a tool washing liquid. CONSTITUTION: This washing method for tools for working aluminum materials comprises dissolving away the aluminum sticking to the tools for aluminum materials in a washing treatment vessel 1 by using a washing liquid consisting of a sodium hydroxide soln. having a high NaOH concn. The sodium hydroxide soln. of 150 to 250g/liter NaOH concn. is used as the washing liquid and the washing liquid is partly and continuously withdrawn as the aged washing liquid from the washing treatment vessel. A flocculating and settling agent is added to this soln. to settle and separate the impurities. The resulted supernatant liquid is introduced into a hydrolyzing vessel 5 where the liquid is hydrolyzed in the presence of crystalline aluminum hydroxide seeds. The suspension is partly withdrawn and is subjected to sepn. of solid from the liquid, by which the crystalline aluminum hydroxide is recovered. The resulted clean liquid is circulated as the regenerated washing liquid to the washing treatment vessel 1 after heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning of a tool for processing an aluminum material, in which a tool used for processing such as plastic working or cutting of an aluminum material made of aluminum or an aluminum alloy is washed with a tool cleaning liquid containing sodium hydroxide. Regarding the method.

[0002]

2. Description of the Related Art For example, as a method for producing an aluminum mold, an extrusion process of an aluminum material is widely adopted. However, when an aluminum mold is produced by this extrusion process, each of them is processed according to the shape of the product. A die is prepared, and an aluminum material as a material passes through the die and is molded into a predetermined shape. When this extrusion operation is completed, the aluminum material is mechanically cut along the die surface, and some of it remains inside the hole of the die, but remains inside the hole of the die for correction and repair. The aluminum material is removed.

The removal of the aluminum material remaining inside the holes of the die is usually carried out by using an aluminum hydroxide solution having a concentration of about 200 to 450 g / liter as a cleaning liquid in the range of 80 to 1
It is carried out by dissolving an aluminum material under heating at about 00 ° C. When this cleaning solution is repeatedly used, aluminum gradually accumulates as sodium aluminate in the aluminum hydroxide of the cleaning solution, and the cleaning solution is accompanied by this. The rate of dissolution of aluminum in aluminum materials decreases, and the workability gradually decreases. If the solubility exceeds that of crystalline aluminum hydroxide (gibbsite), this dibsite precipitates and becomes cloudy, and there is a risk of adhering to vessel walls, etc. Therefore, it is necessary to replace the aged cleaning liquid with a new aluminum hydroxide solution after a predetermined amount of cleaning treatment or after a predetermined time of cleaning treatment. Therefore, the aged cleaning liquid after a predetermined amount or a predetermined time of cleaning process is treated as a waste liquid.

However, the cleaning aging liquid thus discharged during the tool cleaning process is usually 200 to 45.
In addition to containing 0 g / liter of sodium hydroxide, the aluminum content is equal to 0.2 in Al / NaOH equivalent ratio.
Colloids of fine particles such as carbon and boron nitride derived from lubricants used during extrusion processing and oxides such as Mg, Fe and Si derived from aluminum materials, which are dissolved at a concentration of about 0.7 It is contained in a suspended or dissolved state such as a gel or gel.

Therefore, although this cleaning aging liquid contains a large amount of useful sodium hydroxide and aluminum, there is no method for efficiently separating and removing useless impurities, and neutralization treatment is carried out. It is currently being disposed of.
And, in this neutralization treatment, useful sodium hydroxide and aluminum components are simply wasted, and
The use of a large amount of acid is essential for this neutralization process,
In addition, the treatment of the hydrous gel-like aluminum hydroxide sludge containing a large amount of water generated by the neutralization treatment has been added, and the treatment of the waste liquid of the cleaning aging liquid has become one of the great economic burdens.

[0006]

Therefore, the present inventors have earnestly studied a method for effectively cleaning a tool for processing an aluminum material without wasting useful sodium hydroxide and aluminum components. As a result, a sodium hydroxide solution in a predetermined concentration range was used as a tool cleaning liquid, and a coagulating sedimentation agent was added to the cleaning aging liquid that had been aged after a cleaning treatment for a predetermined amount or for a predetermined time, and then sedimentation was performed. It was found that by separating, the fine particle suspension of impurities can be easily separated and removed, and the recovered supernatant can be circulated and used as a cleaning tool cleaning liquid, thus completing the method of the present invention.

Therefore, an object of the present invention is to effectively separate and remove useless impurities from the cleaning and aging liquid of a tool for processing aluminum materials, and recover valuable sodium hydroxide and aluminum components in a useful form. At the same time, another object of the present invention is to provide a method for cleaning a tool for processing an aluminum material, in which the recovered sodium hydroxide solution can be reused as a tool cleaning liquid again.

[0008]

That is, the present invention uses a tool cleaning liquid composed of a sodium hydroxide solution having a high NaOH concentration to heat aluminum adhered to a tool for processing an aluminum material composed of aluminum or an aluminum alloy by heating means. In a method for cleaning an aluminum material processing tool, which is melted and removed under heating in a tool cleaning treatment tank equipped with
NaOH concentration of 150 to 250 g /
Using a liter of sodium hydroxide solution, a part of the tool cleaning liquid is continuously withdrawn as a cleaning aging liquid from the above tool cleaning treatment tank, and a coagulating sedimentation agent is added to the extracted cleaning aging liquid to cause sedimentation separation. Then, the resulting supernatant is cooled and introduced into a hydrolysis tank, and is hydrolyzed in the presence of crystalline aluminum hydroxide seeds in this hydrolysis tank. A part of the suspension is hydrolyzed from the hydrolysis tank. This is a method for cleaning an aluminum material processing tool in which the crystalline aluminum hydroxide is extracted and solid-liquid separated to recover crystalline aluminum hydroxide, and the resulting clear solution is heated and then circulated as a recycled tool cleaning solution in the tool cleaning treatment tank.

In the cleaning method of the present invention, the tool for processing an aluminum material to be cleaned is a tool used during processing such as plastic processing or cutting of an aluminum material, particularly a die used in extrusion processing or the like. It is a tool of. Also,
The tool cleaning solution for cleaning these tools is NaOH
Concentration 150-250 g / liter, preferably 180-
It should be 220 g / l sodium hydroxide solution. When the NaOH concentration of this tool cleaning liquid is lower than 150 g / liter, the hydrolysis reaction rate increases,
The original difference in solubility becomes small, the amount of treatment solution unnecessarily increases, and the apparatus becomes large, which is uneconomical. On the contrary, when it exceeds 250 g / liter, the amount of aluminum dissolved per unit volume increases. In addition, the difference in solubility due to cooling does not increase so much, the hydrolysis reaction is delayed, and the precipitation amount of aluminum content per unit time and unit volume is rather reduced, which lowers the productivity. For example, sodium polyacrylate. Even if a flocculant-precipitating agent such as a high-molecular flocculant is added, efficient sedimentation separation cannot be expected.

In the present invention, when cleaning the tool with the tool cleaning liquid in the tool cleaning treatment tank, the cleaning efficiency is improved,
In order to enhance the hydrolyzability (hydrolysis driving force) for regenerating an aged tool cleaning liquid, and for the stability of the solution, it is usually carried out under heating at 80 ° C. or higher, preferably 90 to 110 ° C. A part of the tool cleaning liquid is continuously withdrawn as a cleaning aging liquid from the cleaning treatment tank. Since the tool cleaning treatment tank requires heating for the tool cleaning treatment, it is necessary to provide a heating means. Examples of this heating means include electric heating and direct or indirect heating with steam. To be done.

The cleaning aging liquid, which is obtained by cleaning the tool in this tool cleaning treatment tank, has a NaOH concentration of 150 to 25.
At 0 g / liter, aluminum content is Al / Na
The OH equivalent ratio can be up to about 0.7, but is preferably about 0.30 to 0.65, more preferably Al / NaO.
It is preferable that the H-equivalent ratio is contained in a concentration of about 0.35 to 0.60. This cleaning aging liquid contains, in addition to aluminum, carbon derived from a lubricant used during processing of an aluminum material, Fine particles such as graphite and boron nitride, and oxides such as Mg, Fe, and Si derived from aluminum materials are in a colloidal or gel-like suspended state (insoluble impurities)
Alternatively, it is contained in a dissolved state (soluble impurities).

In the method of the present invention, when treating the cleaning aging liquid extracted from the tool cleaning treatment tank, a flocculating precipitant is added to the cleaning aging liquid to cause sedimentation separation, and the cleaning aging liquid is added to the aging cleaning liquid. Impurities contained, at least insoluble impurities, are separated and removed as much as possible. The coagulating sedimentation agent used for this purpose may be any that can be used in an aging cleaning solution which is a sodium hydroxide solution having a high NaOH concentration, such as wheat flour, starches, and other sodium polyacrylate-based polymers. Examples thereof include a flocculant, and a sodium polyacrylate-based polymer flocculant is preferable.

The amount of the flocculating precipitant used depends on the concentration of NaOH in the aging cleaning liquid, impurities contained in the aging cleaning liquid,
Although it depends on the amount of insoluble impurities, it is usually the aging cleaning liquid 1
3 to 30 with respect to 1,000,000 (1,000,000) parts by weight
Parts by weight, preferably 5 to 15 parts by weight. If the amount of the flocculating / precipitating agent used is less than 3 parts by weight, the flocculating / precipitating property is poor and the purification is difficult.

In the present invention, the conditions for adding the flocculating sedimentation agent to the cleaning aging liquid and bringing them into contact with each other are particularly limited as long as the flocculation precipitating agent makes sufficient contact with impurities in the cleaning aging liquid. However, when the tool cleaning process is performed under heating, a coagulating sedimentation agent is added to the extracted cleaning aging liquid without cooling, preferably for maintaining sedimentation property and stability of the solution. It is advisable to keep contact with the solution while stirring, keeping in mind the heat retention. For example, when the tool cleaning treatment is performed under heating at 95 ° C, the extracted cleaning aging liquid is preferably contacted under stirring conditions for 70 to 95 ° C, more preferably 80 to 95 ° C. .

In the present invention, the supernatant obtained by this sedimentation separation is then cooled and introduced into a hydrolysis tank, where it is hydrolyzed in the presence of crystalline aluminum hydroxide seeds. Further, impurities, particularly insoluble impurities thereof, are usually condensed and removed in the dense portion in an amount corresponding to 5 to 10% of the total amount of the solution.

The dense portion containing a large amount of impurities generated by the sedimentation separation of the aging cleaning liquid has an amount of 1/10 to 10
Since it is greatly reduced to about 1/25, the object of the present invention can be achieved even if it is directly subjected to waste liquid treatment. However, while it still contains valuable substances such as sodium hydroxide and aluminum, it still requires a troublesome chemical waste liquid treatment process, or it is combined with the waste liquid of a nearby surface treatment factory and the waste liquid is treated collectively. In that case, it may be difficult to use the white gel-like aluminum hydroxide sludge produced there by a solid lubricant or the like, and in such a case, the dense portion is completely solid-liquid separated by a method such as filtration, The useful solution may be collected and combined with the supernatant. In that case, the insoluble matter in the tool cleaning liquid is originally extremely fine, and when it becomes dispersed again, solid-liquid separation becomes difficult. In that case, 0.5-10 g of calcium hydroxide is contained in the dense portion. A clear liquid can be easily obtained by a method such as filtration by adding / liter.

Here, the calcium hydroxide added to the dense portion is not particularly limited, and may be ordinary industrial calcium hydroxide, and if it is a small amount, another alkaline earth metal such as beryllium (Be). ), Magnesium (Mg), strontium (Sr), barium (B
a) and radium (Ra) hydroxide, and some of these alkaline earth metal carbonates, bicarbonates, and other salts that form hydroxides in a strongly alkaline cleaning aging solution May be.

Further, instead of calcium hydroxide itself, a substance which reacts with sodium hydroxide in the dense portion to produce calcium hydroxide, such as calcium carbonate, may be added to the cleaning aging liquid. Well, the addition amount at this time is also such that the concentration of calcium hydroxide produced in the cleaning aging liquid is 0.
It should be in the range of 5 to 10 g / liter. Hereinafter, such a substance that reacts with sodium hydroxide in the dense portion to generate calcium hydroxide may be simply referred to as “calcium hydroxide”.

Here, as the particularly preferable calcium hydroxide, usual industrial calcium hydroxide can be used, but it is an aqueous suspension of calcium hydroxide in order to facilitate dispersion in a dense portion. It is preferably used in the form of lime milk, more preferably in the form of lime milk containing Ca (OH) ₂ at a rate of 10 to 200 g / liter.

The amount of calcium hydroxide added varies depending on the type, content, and dispersion state of impurities in the dense portion to be added. Calcium is replaced by "Ca (O
H) ₂ itself ”is usually added in the range of 0.5 to 10 g / liter, preferably 1 to 4 g / liter. If the amount of calcium hydroxide added is less than 0.5 g / liter, The effect of adding calcium is not sufficiently exerted, and when it is added in excess of 10 g / liter, the amount of solid insoluble matter to be separated and removed becomes too large, and the solid-liquid separation operation becomes troublesome. The added amount of calcium hydroxide can be easily determined by sampling a part of the dense portion, adding a fixed amount of calcium hydroxide to the sample, and performing a sampling test.

Further, the conditions for adding calcium hydroxide to the dense portion and bringing them into contact with each other are not particularly limited as long as the calcium hydroxide is sufficiently brought into contact with the impurities in the dense portion. When the sedimentation separation is carried out under heat retention, it is preferable to add calcium hydroxide to the extracted dense portion without cooling, and bring it into contact with stirring. Further, as the solid-liquid separation after the treatment with calcium hydroxide, a filtration method such as pressure filtration is economically preferable as it is from the viewpoint of simplifying and simplifying the equipment and the operation method.

In the present invention, the supernatant obtained by the sedimentation separation using a coagulating sedimentation agent or the clear liquid obtained by solid-liquid separation by adding calcium hydroxide to the dense portion thereof is then hydrolyzed. It is introduced into a decomposition tank and hydrolyzed in the presence of crystalline aluminum hydroxide (gibsite) seeds. Then, this hydrolysis method is not particularly limited, and conventionally known methods can be appropriately adopted. However, since the solubility of aluminum in a sodium hydroxide solution is greatly affected by temperature, these supernatants are used. For the clarified liquid and the clarified liquid, it is preferably 60 ° C. or lower, more preferably 45 to 55 ° C.
And then the cooled clarified liquid is introduced into a hydrolysis tank where it is hydrolyzed in the presence of crystalline aluminum hydroxide seeds.

The amount of crystalline aluminum hydroxide seeds added during this hydrolysis is about 2 to 6 times, preferably about 3 to 4 times the planned amount of crystalline aluminum hydroxide to be precipitated by hydrolysis. , Solid concentration 150-250g
It is preferable that it is about 1 / liter, and if it is less than 2 times the planned amount, the hydrolysis rate becomes slow, which is not preferable, and if it exceeds 6 times and too much, the hydrolysis rate is improved, but the slurry is dispersed by stirring. It becomes difficult to maintain the condition.

After being hydrolyzed in the hydrolysis tank in this way, a part of the suspension is extracted and solid-liquid separated, and the obtained clear liquid is heated and then regenerated in the tool washing treatment tank. It is circulated as a tool cleaning liquid, and the obtained crystalline aluminum hydroxide (dibsite) is recovered as a valuable resource.

Here, the amount of suspension extracted from the hydrolysis tank is determined by the amount of solution to be refluxed and the solid concentration,
Further, as a method for solid-liquid separation of this suspension, a filtration method such as pressure filtration may be used, but preferably the suspension is precipitated and separated, and the obtained supernatant is heated to perform the tool cleaning treatment. It is circulated in the tank as a cleaning tool cleaning liquid, and a part of the dense portion obtained by this sedimentation separation is filtered to recover crystalline aluminum hydroxide, and the filtrate is circulated in the hydrolysis tank together with the rest of the dense portion. Is good.

Here, in the case where the amount of the recycled tool cleaning liquid or the amount of sodium hydroxide circulated in the tool cleaning treatment tank is less than the tool cleaning liquid (washing aging liquid) extracted from the tool cleaning treatment tank and the balance cannot be balanced. If necessary, a new sodium hydroxide solution is appropriately introduced into the tool cleaning treatment tank so as to keep the overall liquid volume balance.

Further, in the method of the present invention, a supernatant liquid for sedimentation for cooling the tool cleaning liquid (cleaning aging liquid) extracted from the tool cleaning treatment tank and circulating it as a recycled tool cleaning liquid in the tool cleaning treatment tank. (Furthermore, the means for heating the clarified liquid for solid-liquid separation) is not particularly limited, and various cooling means and heating means can be adopted,
A heat exchanger such as a countercurrent bidirectional type is preferable. By using such a heat exchanger, the heat taken out from the tool cleaning treatment tank can be used as effectively as possible. The cooling means may be provided in the hydrolysis tank, and the heating means may be combined with the heating means provided in the tool cleaning treatment tank.

[0028]

According to the method for cleaning a tool for processing aluminum material of the present invention, the NaOH concentration of the tool cleaning liquid used is adjusted to a hydrolyzable concentration, that is, within the range of 150 to 250 g / liter, whereby a coagulating sedimentation agent is prepared. It enables the sedimentation and separation of impurities by means of, and enables the recovered cleaning aging liquid to be continuously hydrolyzed, and can be reused by circulating it as a recycled tool cleaning liquid in the tool cleaning process. In addition to effectively utilizing sodium hydroxide, the aluminum component can be recovered as useful crystalline aluminum hydroxide (dibsite).

[0029]

EXAMPLES The method of the present invention will be specifically described below based on examples and comparative examples. In addition, the measurement value of the insoluble metal oxide fine particles in the following Examples and Comparative Examples "anhydrous equivalent" means that the insoluble matter is filtered and washed with precision filter paper, and then calcined together with the filter paper to obtain the total ash weight. Is a value obtained by subtracting the ash weight of the filter paper from the obtained measured value.

Example 1 A die for extruding an aluminum material was washed at 94 ° C. and then recovered as a wash aging liquid to obtain a NaOH concentration of 240 g.
/ Liter, Al content 88 g / liter, graphite fine particles 20 mg / liter, and other insoluble metal oxide fine particles (anhydrous equivalent) 0.6 g / liter Then, 10 ml of 0.1% solution of sodium polyacrylate-based polymer flocculant (manufactured by Konan Chemical Industry Co., Ltd .: LTX-200S) was added thereto, and the mixture was stirred at 85 ° C. for 5 minutes, and then added to a 1-liter measuring cylinder. After putting it in, it was left to stand in a constant temperature water bath at 85 ° C., and after 2 hours, 800 ml of the supernatant was sampled and its properties were examined.

This supernatant has a NaOH concentration of 238 g / liter and an Al content of 87 g / liter, and is colorless containing 2 mg / liter of graphite-based fine particles and 3 mg / liter of other insoluble metal oxide fine particles (anhydrous equivalent). It was a transparent liquid.

Comparative Example 1 1 liter of the same gray-black suspension die-washing aging liquid used in Example 1 was used, and instead of sedimentation separation using a coagulating sedimentation agent, No. 1 was used. It suction-filtered using the filter paper of 24 on the conditions of 80 degreeC and 0.5 atmosphere. The operation of suction filtration was carried out promptly, but a large amount of solid impurities passed through, and the obtained filtrate was NaO.
H concentration 239 g / liter, Al content 88 g / liter,
Graphite-based fine particles 16 mg / liter, and other insoluble metal oxide fine particles (anhydrous equivalent) 0.4 g /
It had a grayish black suspension of 1 liter and was almost unchanged from that before suction filtration.

Example 2 A die for extrusion of aluminum material was washed at 95 ° C. and then recovered as a wash aging liquid to obtain a NaOH concentration of 210 g.
/ Liter, Al content 77 g / liter, boron nitride-based fine particles 15 mg / liter, and other insoluble metal oxide fine particles (anhydrous equivalent) 0.25 g / liter in a gray suspension-like die cleaning aging liquid 1 liter Then, 10 ml of 0.1% solution of sodium polyacrylate-based polymer flocculant (manufactured by Konan Chemical Industry Co., Ltd .: LTX-200S) was added thereto, and the mixture was stirred at 85 ° C. for 5 minutes, and then added to a 1-liter measuring cylinder. Put it in and leave it in a constant temperature water bath at 85 ° C.
After 2 hours, 800 ml of the supernatant was collected.

Next, 168 g of crystalline aluminum hydroxide (gibsite) seeds (gibsite seed concentration of 210 g / l) were added to 800 ml of the obtained supernatant, and the mixture was added at 55 ° C.
The mixture was hydrolyzed under stirring at 24 hours, while the hydrolysis rate was examined after 24 hours, 48 hours and 72 hours, and then solid-liquid separation was performed by filtration.

The hydrolysis rate after 24 hours was 30%, the hydrolysis rate after 48 hours was 36% and the hydrolysis rate after 72 hours was 39%, and the obtained crystals were beautiful with a purity of 99% or more. It is white, and the finally recovered filtrate is NaO.
H concentration 210 g / liter, Al content 41 g / liter,
Graphite fine particles 1 mg / liter or less, and other insoluble metal oxide fine particles (anhydrous equivalent) 1 mg /
It was a colorless and transparent liquid of liter or less.

Comparative Example 2 Using 1 liter of the same gray-black suspension die-washing aging liquid used in Example 2, instead of sedimentation separation using a coagulating sedimentation agent, No. 3 was used. Suction filtration was performed under the conditions of 80 ° C. and 0.5 atm using the filter paper of No. 24, and the obtained filtrate was hydrolyzed, and the hydrolysis rate, the purity and properties of the obtained crystals, and the filtrate were the same as in Example 2. Was investigated. The solid-liquid separation after hydrolysis cannot be carried out in the same manner as in Example 2, and the operations of centrifugation, revulping and centrifugation were repeated three times.

The hydrolysis rate after 24 hours was 24%, the hydrolysis rate after 48 hours was 32% and the hydrolysis rate after 72 hours was 37%, and the obtained crystals were gray with a purity of 98% and viscous. The filtrate was thick and the final recovered filtrate was NaOH.
It was a suspension opaque liquid having a concentration of 210 g / liter, an Al content of 45 g / liter, graphite-based fine particles of 2 mg / liter, and other insoluble metal oxide fine particles (anhydrous equivalent) of 6 mg / liter.

Example 3 As shown in FIG. 1, a tool cleaning treatment tank 1 equipped with a heating means (not shown), a flocculating sedimentation agent contact tank 2, and a sedimentation separation tank 3
, A heat exchanger 4, a hydrolysis tank 5, and a sedimentation separation tank 6 are connected, and a vacuum filter 7 is connected to the sedimentation separation tank 6 as a solid-liquid separation device. An auxiliary line 8 is provided for joining the filtrate of No. 7 with the supernatant of the sedimentation tank 6 as necessary, and the sedimentation tank 3 is provided with a dense portion to be contacted with lime milk. The contact tank 9 and the vacuum filter 10 were connected to each other, and a line for joining the filtrate from the vacuum filter 10 with the supernatant of the sedimentation separation tank 3 was provided to form a die cleaning line.

In this die cleaning line, the tool cleaning tank 1 has a NaOH concentration of 210 g / liter and Al.
A tool cleaning solution of 3 m ³ at a rate of 80 g / liter was charged, the tool cleaning treatment tank 1 was operated at 95 ° C., and the bath exchange amount was 5.74 m ³ / day. Molecular flocculant (Konan Chemical Industry: LTX
-200S) 57% / day of 0.1% solution was continuously added, and the sedimentation and separation tank 3 was continuously sedimented and separated at 90 ° C.

[0040] From the settling tank 3 extracted and dense portion 0.42 m ³ / day of the supernatant 5.63M ³ / day and 90 ° C. of 90 ° C., for dense portion introduced into the contact vessel 9, wherein Calcium milk with Ca (OH) ₂ concentration of 100 g / liter
After being brought into contact with liters / day, the solution was filtered by a vacuum filter 10 and 0.44 m ³ / day of the recovered filtrate (clarified liquid) was combined with the supernatant of the sedimentation separation tank 3 and introduced into the heat exchanger 4. And cooled to 57 ° C.

Settling / separating tank 3 cooled by this heat exchanger 4.
The supernatant liquid and the filtrate of the vacuum filter 10 are charged into the hydrolysis tank 5, and the hydrolysis tank 5 is maintained at a solution amount of 15 m ³ , a crystalline aluminum hydroxide concentration of 250 to 280 g / liter, and a temperature of 55 ° C. And the residence time in the sedimentation separation tank 6 is set to 1 hour, 5.88 m ³ / day of the supernatant liquid is extracted from the sedimentation separation tank 6, and the heat exchanger 4 is used for 8 hours.
Heat to 5 ° C and add 3k of NaOH to the heated supernatant.
g / day was replenished to prepare a recycled tool cleaning liquid, which was circulated in the tool cleaning treatment tank 1.

Further, a part of the dense portion of 1.1 m ³ / day from the sedimentation separation tank 6 is introduced into a vacuum filter 7, and the filtrate obtained by filtering there is the rest of the dense portion from the sedimentation separation tank 6. It was combined with 1.7 m ³ / day and circulated again in the hydrolysis tank 5, and crystals were washed with 0.27 m ³ / day of water from the top of the cake of the vacuum filter 7 and then crystallized as a product. Aluminum hydroxide was recovered.

In the tool cleaning treatment tank 1, about 150 kg / day of the aluminum material attached to the die and brought into the die is melted, and in the vacuum filter 10, the filter cake 1 having a moisture content of about 50% is melted.
3 kg / day was collected, and 501 kg / day of crystalline aluminum hydroxide (adhered water content: 10% by weight) was recovered from the water washing tank 8 as a product.

The crystalline aluminum hydroxide obtained was a beautiful white crystal having a purity of 99% or more. Furthermore, this die cleaning line was continuously operated for 20 days, but the tool cleaning liquid in the tool cleaning treatment tank 1 was not the planned NaO.
The H concentration was maintained at 210 g / liter and the Al content was 80 g / liter, and the operation was smooth.

Comparative Example 3 A tool cleaning treatment tank was constructed with a NaOH concentration of 300 g / liter.
Material cleaning liquid 2.4m^Three, And this tool cleaning tank
5 ° C, average bath exchange 1.2m^Three/ Day drive to waste
Cleaning aging liquid extracted (NaOH concentration 300 g / liter
And a concentration of Al of 125 g / liter),
Actual capacity of 10 m using 480 kg / day of acid ^ThreeDilution neutralization tank
At 75m^ThreeNeutralization at a rate of / day, followed by sedimentation
Solid-liquid separation was performed and the filtrate was subjected to wastewater treatment. At this time, in processing
Difficult-to-use hydrous gel aluminum hydroxide containing 75% water
The amount of sludge generated reached 1,900 kg / day.

[0046]

According to the method of cleaning a tool for processing aluminum materials of the present invention, unnecessary impurities are effectively separated and removed from the cleaning aging liquid generated by the cleaning treatment of the tool for processing aluminum materials, and it is a valuable resource. The sodium hydroxide and aluminum components can be recovered in a useful form.

Further, the cleaning aging liquid of the tool for processing an aluminum material that has been collected can be efficiently regenerated, and can be circulated and reused again as a regenerated tool cleaning liquid, so that it is difficult to process filter cake and hydrous gel-like aluminum hydroxide sludge. Generation can be suppressed as much as possible, and consumption of sodium hydroxide and sulfuric acid for neutralization can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a flow chart of a die cleaning line showing a method for cleaning an aluminum material processing tool according to a third embodiment of the present invention.

[Explanation of symbols]

1 ... Tool cleaning treatment tank, 2 ... Coagulation sedimentation agent contact tank, 3, 6
… Sedimentation separation tank, 4… Heat exchanger, 5… Hydrolysis tank, 7, 1
0 ... Vacuum filter, 8 ... Auxiliary line, 9 ... Lime milk contact tank.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C23F 1/36 C23F 1/36 1/46 1/46 C23G 1/36 C23G 1/36 (72) Inventor Yoshiro Tanaka 3-13-12 Mita, Minato-ku, Tokyo Within Japan Light Metals Co., Ltd.

Claims (5)

[Claims] 1. A tool cleaning liquid consisting of a sodium hydroxide solution having a high NaOH concentration is used to heat aluminum attached to a tool for processing an aluminum material composed of aluminum or an aluminum alloy in a tool cleaning treatment tank equipped with a heating means. In a method for cleaning a tool for processing an aluminum material, which is dissolved and removed in a solvent, a NaOH concentration of 15 is used as the tool cleaning liquid.
Using a sodium hydroxide solution of 0 to 250 g / liter, a part of the tool cleaning liquid is continuously withdrawn as a cleaning aging liquid from the tool cleaning treatment tank, and a coagulating sedimentation agent is added to the extracted cleaning aging liquid. Then, the supernatant liquid obtained is cooled, introduced into a hydrolysis tank, hydrolyzed in the presence of crystalline aluminum hydroxide seeds in this hydrolysis tank, and suspended from the hydrolysis tank. A part of the aluminum material is characterized in that it is solid-liquid separated and crystalline aluminum hydroxide is recovered, and the resulting clear solution is heated and then circulated as a recycled tool cleaning solution in the tool cleaning treatment tank. Method for cleaning tools. 2. A suspension extracted from the hydrolysis tank is separated by sedimentation, and the obtained supernatant is heated and circulated as a recycled tool cleaning liquid in the above tool cleaning treatment tank. The method for cleaning an aluminum material processing tool according to claim 1, wherein a part of the dense portion is filtered to recover the crystalline aluminum hydroxide, and the filtrate is circulated in the hydrolysis tank together with the rest of the dense portion. 3. A tool cleaning treatment tank performs a tool cleaning treatment at 90 to 110 ° C. to obtain an Al / NaOH equivalent ratio of 0.35.
The washing aging solution of 0.60 was taken out, and it was 45 in the hydrolysis tank.
While hydrolyzing at ~ 60 ° C, the suspension extracted from this hydrolysis tank is subjected to solid-liquid separation to collect a clear liquid having an Al / NaOH equivalent ratio of 0.25 to 0.40 as a regenerating tool cleaning liquid, The method for cleaning an aluminum material processing tool according to claim 1, which is circulated in a tool cleaning treatment tank. 4. A dense portion obtained by adding a coagulating sedimentation agent to a washing aging liquid and then separating by sedimentation, adding 0.5 to 10 g / liter of calcium hydroxide, and then solid-liquid separation by filtration to clarify. The method for cleaning an aluminum material processing tool according to any one of claims 1 to 3, wherein the liquid is recovered and the recovered clear liquid is circulated in a hydrolysis tank. 5. Ca is added as calcium hydroxide.
The method for cleaning an aluminum material processing tool according to claim 4, wherein lime milk having a concentration of (OH) ₂ 10 to ₂₀₀ g / liter is added.