阅读说明：本技术 一种铝合金型材碱蚀生产工序中碱液回收再利用的方法 (Method for recycling alkali liquor in aluminum alloy section bar alkali etching production procedure ) 是由 廖健 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种铝合金型材碱蚀生产工序中碱液回收再利用的方法,它包括以下步骤：S1、铝合金型材的碱蚀；S13、当碱蚀30~54min后,将铝合金型材从槽液中取出,从而完成了铝合金型材的碱蚀；S2、NaOH溶液的回收再利用,具体包括以下步骤：S21、检测槽液中Al<Sub>3</Sub><Sup>+</Sup>的浓度,当Al<Sub>3</Sub><Sup>+</Sup>浓度达到28g/L时,采用泵将碱蚀槽内的槽液抽排到晶析槽内；S23、采用泵将上层NaOH溶液抽排到回收桶中,然后将回收桶内的NaOH溶液倾倒于碱蚀槽内继续用于生产,形成闭路循环生产,从而实现了NaOH溶液的回收再利用；S3、铝离子的回收。本发明的有益效果是：提高型材表面质量稳定性、降低氢氧化钠损耗、减轻后期污水处理的困难、提高经济效益。(The invention discloses a method for recycling alkali liquor in an aluminum alloy section alkali etching production process, which comprises the following steps of S1 alkali etching of an aluminum alloy section, S13 taking the aluminum alloy section out of a tank liquor after 30 ~ 54min of alkali etching so as to finish the alkali etching of the aluminum alloy section, and S2 recycling NaOH solution, and specifically comprises the following steps of S21 detecting Al in the tank liquor 3 + When the concentration of Al is 3 + When the concentration reaches 28g/L, pumping and discharging the bath solution in the alkaline etching bath into a crystallization bath by using a pump; s23, pumping the upper NaOH solution into a recycling bin by a pump, pouring the NaOH solution in the recycling bin into an alkaline etching tank for continuous production to form a closed containerThe way is circulated for production, thereby realizing the recycling of NaOH solution; s3, and recovering aluminum ions. The invention has the beneficial effects that: the surface quality stability of the sectional material is improved, the sodium hydroxide loss is reduced, the difficulty of later-stage sewage treatment is reduced, and the economic benefit is improved.)

1. A method for recycling alkali liquor in an aluminum alloy section alkali etching production procedure is characterized by comprising the following steps: it comprises the following steps:

s1, alkaline etching of the aluminum alloy section, which comprises the following steps:

s11, filling tank liquor consisting of NaOH solution and organic acid sodium salt solution into an alkaline etching tank, and raising the temperature of the tank liquor to 45 ~ 50 ℃;

s12, placing the aluminum alloy section to be subjected to alkaline etching into an alkaline etching tank, removing a natural oxide film on the surface of the aluminum alloy section and slight scratches on the surface of the aluminum alloy section by using NaOH solution, exposing the aluminum alloy section to be uniformly, freshly and ideally, and simultaneously generating a large amount of Al with high added value in the tank liquor₃ ⁺Organic acid sodium salt and Al₃ ⁺The complexing reaction is carried out to generate NaAlO₂，NaAlO₂No or little hydrolysis, with the Al (OH) initially formed by hydrolysis₃The crystal nucleus particles do not grow up;

s13, taking the aluminum alloy section out of the bath solution after the alkali etching is carried out for 30 ~ 54min, thereby completing the alkali etching of the aluminum alloy section;

s2, recycling NaOH solution, and specifically comprising the following steps:

s21, detecting Al in bath solution₃ ⁺When the concentration of Al is₃ ⁺When the concentration reaches 28g/L, pumping and discharging the bath solution in the alkaline etching bath into a crystallization bath by using a pump;

s22, adding a proper amount of clear water into the crystallization tank to dilute the tank liquor, standing for 15 ~ 32min after dilution to cool the tank liquor, stirring the tank liquor by a stirrer after cooling, wherein the stirring speed is 540 ~ 550r/min, and promoting NaALO in the alkali liquor₂Hydrolysis, generating NaOH solution and Al (OH) after hydrolysis₃Slurry, after 12 ~ 20min standing, NaOH solution and Al (OH)₃Slurry demixing, Al (OH)₃The slurry is deposited at the bottom of the crystallizer and the NaOH solution is in Al (OH)₃An upper layer of slurry;

s23, pumping the upper NaOH solution into a recovery barrel by using a pump, pouring the NaOH solution in the recovery barrel into an alkaline etching tank for continuous production to form closed cycle production, thereby realizing the recovery and reutilization of the NaOH solution;

s3, recovering aluminum ions, which specifically comprises the following steps:

s31, opening the valve at the bottom of the crystallizer tank, and adding Al (OH)₃Discharging the slurry, sampling after flowing out for 2-3 min, and measuring Al (OH) after the sample is static for 45 ~ 47min₃The concentration of (c);

s32, detecting Al (OH)₃When the slurry concentration is 38-40%, all Al (OH) is discharged₃The slurry was then washed with a centrifuge to remove Al (OH)₃Slurry to obtain dry Al (OH)₃A crystal;

s33, pumping the separated washing liquid back to the crystallization tank.

2. The method for recycling the alkaline solution in the alkaline etching production process of the aluminum alloy profile according to claim 1, which is characterized in that: the method also comprises a crystallization tank maintenance step, wherein the specific maintenance step is to detect the temperature in the crystallization tank, when the temperature of the crystallization tank reaches 44 ℃, the top cover of the crystallization tank is opened by half, and when the temperature of the crystallization tank is more than or equal to 45 ℃, the top cover of the crystallization tank is completely opened.

Technical Field

The invention relates to a method for recycling alkali liquor in an aluminum alloy section bar alkali etching production procedure.

Background

The production scale and the product quality of the building aluminum profile in China are improved, and the surface treatment process, quality and equipment are in contact with the international advanced level; with the increasing shortage of resources and energy, the continuous enhancement of environmental protection consciousness and the optimized recombination of industrial production, the aluminum profile production process is developed towards low energy consumption, low pollution and green environmental protection, and the influence of the anodic oxidation process on the environment is reduced as much as possible on the premise of ensuring the service performance.

Before the chemical pretreatment of the anodic oxidation surface treatment, the aluminum alloy section needs to be subjected to alkaline etching, and a natural oxide film on the surface of the aluminum alloy section and slight scratches on the surface of the section are removed by alkali liquor, so that the section is exposed to a uniform, fresh and ideal surface, and the anodic oxidation treatment of the aluminum alloy section in the later period is facilitated, therefore, the alkaline etching plays a crucial role in the surface quality of the aluminum material, and is a very important process. A large amount of Al with high added value is generated in the alkaline etching process₃ ⁺And the accumulated liquid in the tank can be precipitated, dehydrated, agglomerated and hardened to a certain degree, and is combined with the tank wall very firmly, so that a large amount of water is needed to wash the alkaline etching tank, and the influence on production is great. Due to a large amount of Al₃ ⁺Causes aluminum ions to combine with hydroxide ions in the NaOH solution, consumes a large amount of the NaOH solution, increases the cost of caustic etching, and generates a large amount of Al (OH) in the bath after combination₃The slurry, which is difficult to treat in the later stage. In addition, a large amount of Al₃ ⁺The existence of (2) makes the surface quality of the aluminum alloy section unstable, has larger difference, and reduces the quality of the section.

The tank liquor adopted by the alkaline etching is NaOH solution and organic acid sodium salt solution, and the organic acid sodium salt causes aluminum ions generated in the alkaline etching process to generate complexation with the aluminum ions so as to generate NaAlO₂，NaAlO₂No or little hydrolysis, with the Al (OH) initially formed by hydrolysis₃The crystal nucleus particles do not grow, and even if soft precipitation instead of hard blocks occurs, the problems of unstable surface quality and high mud yield of the aluminum alloy section cannot be solved. In order to solve the problems, nitrate or nitrite is added into the bath solution, so that the surface brightness can be improved, but ammonia nitrogen pollution is generated; the addition of the surfactant and the tackifier can ensure that the sand surface etched by the alkali has better effect but generates a large amount of sludge; also added corrosion inhibitorsTo reduce the consumption of alkali, but still have the following drawbacks: (1) the viscosity is high: the tank liquor of the alkaline etching additive can only be mixed with high-concentration Al₃ ⁺The method comprises the steps of (100 ~ 150 g/L) coexistence, uniform and corrosion inhibition reaction between alkali liquor and aluminum materials to achieve leveling effect, and better alkali sand effect, (2) higher alkali corrosion liquor temperature (50 ~ 75 ℃) and higher concentration (55 ~ 70 g/L), and (3) high water consumption, wherein the alkali liquor with higher concentration and viscosity is attached to the surface of the alkali corrosion aluminum material, and needs to be intensively washed by clear water.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for recycling alkali liquor in the alkali etching production process of aluminum alloy sections, which improves the surface quality stability of the sections, reduces the loss of sodium hydroxide, relieves the difficulty of later-stage sewage treatment and improves the economic benefit.

The purpose of the invention is realized by the following technical scheme: a method for recycling alkali liquor in an aluminum alloy section alkali etching production procedure comprises the following steps:

s1, alkaline etching of the aluminum alloy section, which comprises the following steps:

s11, filling tank liquor consisting of NaOH solution and organic acid sodium salt solution into an alkaline etching tank, and raising the temperature of the tank liquor to 45 ~ 50 ℃;

s12, placing the aluminum alloy section to be subjected to alkaline etching into an alkaline etching tank, removing a natural oxide film on the surface of the aluminum alloy section and slight scratches on the surface of the aluminum alloy section by using NaOH solution, exposing the aluminum alloy section to be uniformly, freshly and ideally, and simultaneously generating a large amount of Al with high added value in the tank liquor₃ ⁺Organic acid sodium salt and Al₃ ⁺The complexing reaction is carried out to generate NaAlO₂，NaAlO₂No or little hydrolysis, with the Al (OH) initially formed by hydrolysis₃The crystal nucleus particles do not grow up;

s13, taking the aluminum alloy section out of the bath solution after the alkali etching is carried out for 30 ~ 54min, thereby completing the alkali etching of the aluminum alloy section;

s2, recycling NaOH solution, and specifically comprising the following steps:

s21, detecting Al in bath solution₃ ⁺When the concentration of Al is₃ ⁺When the concentration reaches 28g/L, pumping and discharging the bath solution in the alkaline etching bath into a crystallization bath by using a pump;

s22, adding a proper amount of clear water into the crystallization tank to dilute the tank liquor, standing for 15 ~ 32min after dilution to cool the tank liquor, stirring the tank liquor by a stirrer after cooling, wherein the stirring speed is 540 ~ 550r/min, and promoting NaALO in the alkali liquor₂Hydrolysis, generating NaOH solution and Al (OH) after hydrolysis₃Slurry, after 12 ~ 20min standing, NaOH solution and Al (OH)₃Slurry demixing, Al (OH)₃The slurry is deposited at the bottom of the crystallizer and the NaOH solution is in Al (OH)₃An upper layer of slurry;

s23, pumping the upper NaOH solution into a recovery barrel by using a pump, pouring the NaOH solution in the recovery barrel into an alkaline etching tank for continuous production to form closed cycle production, thereby realizing the recovery and reutilization of the NaOH solution;

s3, recovering aluminum ions, which specifically comprises the following steps:

s31, opening the valve at the bottom of the crystallizer tank, and adding Al (OH)₃Discharging the slurry, sampling after flowing out for 2-3 min, and measuring Al (OH) after the sample is static for 45 ~ 47min₃The concentration of (c);

s32, detecting Al (OH)₃When the slurry concentration is 38-40%, all Al (OH) is discharged₃The slurry was then washed with a centrifuge to remove Al (OH)₃Slurry to obtain dry Al (OH)₃A crystal;

s33, pumping the separated washing liquid back to the crystallization tank.

The method also comprises a crystallization tank maintenance step, wherein the specific maintenance step is to detect the temperature in the crystallization tank, when the temperature of the crystallization tank reaches 44 ℃, the top cover of the crystallization tank is opened by half, and when the temperature of the crystallization tank is more than or equal to 45 ℃, the top cover of the crystallization tank is completely opened.

The invention has the following advantages:

1. the concentration of the alkali liquor flowing back to the alkali etching tank after hydrolysis is higher than that of the flowing alkali liquor, so that the consumption of NaOH in the alkali etching process can be supplemented, and only the amount of alkali taken away by the aluminum alloy section is needed to be supplemented in production, so that the loss of NaOH solution is effectively reduced.

2. Al in alkaline etching liquid in alkaline recovery production control₃ ⁺｛Al(OH)₃Can effectively recycle Al in the bath solution₃ ⁺

The removal rate can reach 55 percent; about 25-30 kg of pure Al (OH) containing 10-15% of water can be generated per ton of silver white material (containing sand blasting material)₃Can effectively reduce the sludge of wastewater treatment and achieve the purpose of preventing and treating pollution.

3. Alkali liquor can be regenerated and recycled, the loss of liquid NaOH (30%) is about 70 kg/ton lower than that of the additive for alkaline corrosion, and no additive is added into the bath solution; recovered dry Al (OH)₃The content of the crystals reaches more than 90 percent, has great economic benefit and can be processed into alum, cryolite, inorganic flame retardant and the like.

4. The method has the advantages that the recycling production process flow is reasonably adopted, the loss and discharge of produced medicines are reduced, resources are recycled, the discharge of wastes is reduced, the environment-friendly pressure is reduced, the production process with long process flow, high water consumption, high energy consumption and much heavy metal is gradually abandoned, and a new green, environment-friendly and efficient surface treatment technology is developed, so that the economic sustainable development is realized.

Drawings

FIG. 1 is a process flow diagram for alkali recovery.

Detailed Description

The invention will be further described with reference to the accompanying drawings, without limiting the scope of the invention to the following: