CN108166011B

CN108166011B - Aluminum industry slag reduction oil removal and chromizing agent compatible and pollution reduction spraying system

Info

Publication number: CN108166011B
Application number: CN201711471764.9A
Authority: CN
Inventors: 熊映明
Original assignee: Foshan Sanshui Xiongying Innovation Center For Aluminum Surface Technnologies Co ltd
Current assignee: Foshan Sanshui Xiongying Innovation Center For Aluminum Surface Technnologies Co ltd
Priority date: 2017-12-29
Filing date: 2017-12-29
Publication date: 2020-06-23
Anticipated expiration: 2037-12-29
Also published as: CN108166011A

Abstract

The invention discloses a degreasing and chromizing agent compatible and pollution-reducing spraying system for slag reduction in aluminum industry, which comprises an oil removing groove, a first non-flowing water washing groove group, a chromizing groove, a second non-flowing water washing groove group, a spraying groove and a draining groove, wherein aluminum sequentially passes through the oil removing groove, the first non-flowing water washing groove group, the chromizing groove, the second non-flowing water washing groove group, the spraying groove and the draining groove; the oil removing tank and the second non-flowing water washing tank group are respectively communicated with the first non-flowing water washing tank group, oil removing liquid is arranged in the oil removing tank, chromizing liquid is arranged in the chromizing tank, and the oil removing liquid and the chromizing liquid are compatible with each other; the water pump is used for pumping water in the spraying groove and the draining groove into the second non-flowing water washing groove set. The compatibility of the selected components to the degreasing fluid is concerned for the first time. The invention realizes zero discharge of waste water and waste residue in spray chromizing treatment and water saving in production.

Description

Aluminum industry slag reduction oil removal and chromizing agent compatible and pollution reduction spraying system

Technical Field

The invention relates to the technical field of metal surface treatment, in particular to a spraying system for aluminum industry slag reduction, which is compatible with an oil removing and chromizing agent and capable of reducing pollution.

Background

The aluminum and the aluminum alloy have the advantages of excellent processing performance, good corrosion resistance, beautiful surface, high recovery rate and the like, are widely applied to the industries of buildings, transportation, machinery, electric power and the like, and have more obvious trend of expanding the application of the aluminum by replacing the steel with the aluminum in recent years. The aluminum processing industry is a traditional industry, and more particularly, the sunrise industry which is full of bobby vitality. According to statistics, developed countries in Europe and America consume more than 32kg of aluminum materials per year, but China only has about 13kg of aluminum materials per year and is only about one third of developed countries, and domestic aluminum material consumption has huge growth space, but under the new economic normal state, the problems of high energy consumption, large total pollution discharge amount and low resource recovery rate also become bottlenecks and obstacles for industry development.

The production in the aluminum industry comprises the working procedures of electrolysis, casting, pressure processing, surface treatment and the like, and waste water and waste residues are generated in different degrees in all the working procedures during production. A large amount of aluminum ash is generated during electrolysis and casting, alkaline waste liquid is corroded by alkali in the extrusion process, and various waste water and waste residues containing acid, alkali, treatment agents, chromium, nickel heavy metal ions and other complex components are generated in the surface treatment process.

The spraying pretreatment of the chromium-containing toxic waste residue generated by oil removal and chromizing accounts for 20 percent of the total amount of the waste residue generated by surface treatment of aluminum processing enterprises.

The powder spraying aluminum profile has the advantages of beautiful surface, rich colors, good corrosion resistance and weather resistance, and the like, and becomes the largest surface treatment variety of the aluminum profile, and accounts for more than 60 percent of the total amount. The surface of the section bar is pretreated before spraying, a layer of compact conversion coating is generated on the surface of the aluminum material through chemical reaction, the conversion coating has certain corrosion resistance, and more importantly, the base material and the spraying coating can be firmly combined together.

Chromium-containing wastewater is generated after spraying chromizing pretreatment, chromium belongs to a class of pollutants, the wastewater is collected and treated independently, and the wastewater can be discharged after reaching the standard. The waste water containing hexavalent chromium is generally treated by an oxidation-reduction method, i.e. reducing agents such as ferrous sulfate and sodium pyrosulfite are used to treat Cr in the waste water⁶+ reduction to Cr³⁺Then, the pH value of the wastewater is adjusted to 7-8, and alkali and flocculating agent are added to lead Cr to be³⁺Formation of Cr (OH)₃Precipitating, and dehydrating by flocculation, sedimentation and filter pressing to form chromium hydroxide (trivalent chromium) chromium slag. The flow of the chromium-containing wastewater treatment is shown in FIG. 3. The chromium slag belongs to dangerous waste and must be legally transferred to a qualified third-party institution for standard disposal.

In a word, the treatment and disposal cost of the chromium-containing wastewater and waste residue is high, the enterprise is heavily burdened, and the method has environmental hazard, regardless of 'talking about chromium color change' of governments or enterprises.

In order to solve the pollution problem caused by the chromizing process, a large amount of chromium-free process substitution researches are carried out at home and abroad for many years and are generally applied to the aluminum profile industry. The chromium-free process mainly comprises two technical routes, namely a titanium-zirconium system and a silane system, and the chromium-free passivation process of fluotitanic acid and fluozirconic acid of the titanium-zirconium system is mainly applied in Chinese aluminum section factories. The quality of the passive film and the spraying layer of the process can basically meet the requirement of GB 5237, but the passive film and the spraying layer are inferior to a chromized film in certain indexes and overall stability, and the passive film and the spraying layer are not subjected to outdoor long-term inspection. And the chromium-free passivation process has strict control requirements, the conversion film has no color, the quality of the film layer is difficult to judge on site, and the product is likely to be unqualified if careless. In order to ensure the product quality, the fluorocarbon paint spraying section bar and the curtain wall veneer still adopt the chromizing process. More importantly, chromium-free reagents such as fluotitanic acid and fluozirconic acid contain fluorine, and the pollution problem of the fluorine is caused by using the chromium-free chemical reagents with strong toxicity. The front door drives wolf and the back door drives tiger, and the process of replacing pollution by the same non-environment-friendly process is not the optimal choice.

Among all the chemical conversion coatings, the chromized coating has the best corrosion resistance and has a self-repairing function, which is related to the retention of hexavalent chromium in the coating structure, and the corrosion resistance of other chemical conversion coatings can not reach the level of the chromized coating. Therefore, the chromizing process is still irreplaceable as long as the problem of hexavalent chromium wastewater and waste residue pollution of the chromizing process is solved.

The chromate chemical conversion treatment is the most common aluminum product pretreatment process, has been applied for decades at home and abroad, has mature technology, easy control of the process, good quality of a chromizing film layer and very stable quality of a spraying layer. However, hexavalent chromium contained in the chromating solution and the conversion coating has strong toxicity, and governments have set a series of policies to limit the adoption of the process in some fields, the most important of which is that: on 13.2.2003, the "RoHS directive" for restricting the use of 6 toxic and harmful substances such as hexavalent chromium in electrical and electronic equipment, which is passed through by the european union, is mainly directed to electrical and electronic equipment products. However, in other fields, such as aerospace, building aluminum alloy doors, windows and curtain walls, no relevant foreign policy report is found at present. In Europe and America, the spraying pretreatment of aluminum profiles and curtain wall aluminum plates also adopts a great deal of chromizing treatment process.

In recent years, national environmental protection regulation is becoming stricter, and many local governments in China take the environmental hazards of hexavalent chromium and trivalent chromium in the traditional chromate passivation to waste water and waste residue and the difficulty in treatment and regulation into consideration, and develop an environmental protection policy of strictly limiting the adoption of the traditional chromium-containing passivation process. The Buddha mountain is the most concentrated area of aluminum products in China, the aluminum profile industry is one of the pillar industries in the Buddha mountain market, how to actively and scientifically deal with the national environmental protection laws and regulations, guide enterprises to grasp opportunity transformation and upgrade, accelerate the popularization and application of a spraying pretreatment process without generating waste water and waste residues, protect the environment and benefit descendants, and the Buddha mountain aluminum profile is worthy of common discussion and thinking of governments and enterprises.

Modern aluminum processing enterprises have the urgent need of treating waste water and waste residue after spraying pretreatment, but the existing treatment method is too simple, and the chromium-containing waste water and waste residue generated by the chromizing process and the fluorine-containing waste water and waste residue generated by the chromium-free process all face the environmental protection pressure of treating the toxic waste water and waste residue. The society will pay for expensive disposal costs to dispose of these wastes.

In the prior art, the spraying pretreatment process flow is as follows: hanging workpieces → acid etching and degreasing → water washing → chromizing → water washing → draining → drying → coating. The production line for the aluminum profile coating pretreatment is divided into 2 types of vertical lines and horizontal lines, wherein the vertical lines adopt a full-automatic spraying mode; the horizontal wire was dipped all at once as shown in fig. 6.

The No. 1 acid oil removing tank is generally selected from sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, hydrofluoric acid, sodium fluoride, ammonium bifluoride and a proper amount of surfactant for oil removal. When the aluminum material is deoiled, the aluminum is subjected to the following chemical reaction in deoiling liquid containing mixed acid and fluorine:

1. removing natural oxide film

Al₂O₃+6H⁺＝2Al³⁺+3H₂O (1)

2. Melting aluminum and deburring

2Al+6H⁺＝2Al³⁺+3H₂↑ (2)

3. Aluminum-fluorine complexing and stable deoiling liquid

6Al³⁺+F^-+H₂O＝AlF₆ ^3-+Al(OH)F₅ ^3-+Al(OH)₂F₄ ^3-

+Al(OH)₃F₃ ^3-+Al(OH)₄F₂ ^3-+Al(OH)₅F^3-+6H⁺(3)

4. Passivating the aluminum surface and reducing the dissolved aluminum

2Al+3NO₃ ^-＝Al₂O₃+3NO₂ ^-(4)

According to the formulas (1) and (2), the higher the acid concentration is, the faster the aluminum dissolving speed is; according to the formulas (3) and (4), the surface of the aluminum material is passivated, the amount of dissolved aluminum is restricted, and the pressure of crystal precipitation of bath solution is reduced; meanwhile, due to the existence of high-concentration nitric acid, aluminum exists in the forms of fluoroaluminate and hydroxyfluoroaluminate instead of being precipitated and separated out by aluminum fluoride or aluminum phosphate, the bath solution is stable, does not decompose, does not scale and can run for a long time.

4# chromizing tank, typically containing CrO₃Potassium dichromate K₂Cr₂O₇Sodium fluoride, nitric acid, potassium ferricyanide K₃Fe(CN)₆Sodium silicate Na₂SiO₃Hydrofluoric acid, boric acid, sodium molybdate, a stabilizer (prepared by mixing 2 organic acids containing carboxyl and hydroxyl), and the like. When the aluminum material is chromized, a layer of passivation film which is difficult to dissolve in water and mainly consists of chromate is formed on the surface of the metal. The 4# groove chromizing film-forming process is relatively complex, and the reaction mechanism is as follows:

1. dissolving aluminum and precipitating hydrogen on the surface of aluminum material

2Al+6HF＝2AlF₃+3H₂↑ (5)

AlF₃Reacting according to (3) to produce fluoroaluminic acid and hydroxyfluoroaluminic acid

2. The separated hydrogen reduces the hexavalent chromium into trivalent chromium, and the trivalent chromium is deposited on the surface of the aluminum in the form of chromium hydroxide colloid due to the increase of the pH value at the two-phase interface of the aluminum alloy and the chromizing liquid

3H₂+2CrO₃＝2Cr(OH)₃↓ (6)

3. The chromium hydroxide colloid is combined with hexavalent chromium to form trivalent chromium and hexavalent chromium oxide on the surface of aluminum

2Cr(OH)₃+CrO₃＝Cr(OH)₃·Cr(OH)·CrO₄↓

+H₂O＝Cr(OH)₃·Cr(OH)₂·HCrO₄↓ (7)

4. The pH value of the interface of two phases of the aluminum alloy and the chromizing liquid is increased, so that aluminum ions and hydroxide radicals generate gelatinous aluminum hydroxide, and the aluminum hydroxide is dehydrated on the surface of the aluminum alloy to form an alumina film which is difficult to dissolve in water

2Al³⁺+6OH^-＝2Al(OH)₃↓＝Al₂O₃↓+3H₂O (8)

5. The fluoroaluminate electrically adsorbed on the surface of the aluminum alloy reacts with trivalent chromium to generate a chromium fluoroaluminate film

Cr³⁺+AlF₆ ^3-＝CrAlF₆↓ (9)

6. Molybdate is used as an oxidative promoter, and the molybdate and aluminum ions form an aluminum molybdate compound protective film on the surface of aluminum

3H₂MoO₄+2Al³⁺＝Al₂(MoO₄)₃↓+6H⁺(10)

7. With potassium ferricyanide K₃Fe(CN)₆As an oxidation promoter, potassium ferricyanide and aluminum ions form an aluminum ferricyanide composite protective film on the surface of aluminum

Fe(CN)₆ ^3-+Al³⁺＝AlFe(CN)₆↓ (11)

8. Nitric acid is used as a bath solution stabilizer and a dust remover to remove the virtual dust on the surface of the aluminum profile chromizing film, limit the precipitation of sludge in the chromizing bath and oxidize trivalent chromium to hexavalent chromium.

The composition of the chromate conversion coating is substantially CrAlF₆·AlFe(CN)₆·Al₂(MoO₄)₃·Cr(OH)₃·Cr(OH)₂·CrO₄·Al₂O₃·H₂O, the newly generated conversion film exists in a colloid state, the hardness and the wear resistance are poor, the conversion film is dehydrated and hardened after being dried, has hydrophobicity, and has good bonding force with an aluminum material substrate and corrosion resistance, and is a good bottom layer of an organic coating.

According to the figure 6, the chromizing aluminum material is produced, and long-term operation shows that crystals exist at the bottom of the oil removing groove, chromium-containing sludge exists at the bottom of the chromizing groove, the chromium-containing sludge needs to be cleaned regularly, the sludge contains highly toxic hexavalent chromium, and the operation is very dangerous.

Ammonium fluoride, ammonium bifluoride, sodium fluoride and phosphoric acid in the acidic oil removal tank are components which cause the surface of the aluminum material to be easy to be coated with ash and generate crystal precipitates. When the acidity value of the bath solution is not enough, acid corrosion ash is easily generated on the surface of the aluminum material, and the oil removal effect is influenced; sodium ions in the sodium fluoride are easy to generate sodium fluoroaluminate precipitate, and the tank liquor needs to be cleaned; phosphoric acid is easy to generate aluminum phosphate precipitate, and the tank liquor needs to be cleaned.

Potassium dichromate K in chromizing tank₂Cr₂O₇Sodium fluoride, potassium ferricyanide K₃Fe(CN)₆Sodium silicate Na₂SiO₃The sodium molybdate is a component which makes the surface of the aluminum material easy to be coated with ash and easy to generate crystal precipitates. The components contain sodium and potassium, sodium fluoroaluminate and potassium fluoroaluminate precipitates are easy to generate, and a tank needs to be cleaned; meanwhile, the products can make the bath solution unclear and the chromizing film is easy to be coated with ash, thereby affecting the chromizing quality.

The stabilizer in the chromizing tank is prepared and combined by 2 organic acids containing carboxyl and hydroxyl, and is an unstable component easy to be oxidized and decomposed in the chromizing liquid. These are reducing components in the presence of chromium-containing anhydrides (CrO)₃) Hydrofluoric acid, nitric acid and boric acid are easily decomposed by an oxidant, and the stability of the chromizing liquid is affected.

Disclosure of Invention

The invention aims to provide a spray system which is compatible with degreasing and chromizing agents and can reduce pollution and reduce slag in the aluminum industry, and has the characteristics of saving water and reducing pollution.

In order to achieve the purpose, the invention adopts the following technical scheme:

a degreasing and chromizing agent compatible and pollution-reducing spraying system for slag reduction in aluminum industry comprises an oil removing groove, a first non-flowing water washing groove group, a chromizing groove, a second non-flowing water washing groove group, a spraying groove and a draining groove, wherein aluminum sequentially passes through the oil removing groove, the first non-flowing water washing groove group, the chromizing groove, the second non-flowing water washing groove group, the spraying groove and the draining groove; the oil removing tank and the second non-flowing water washing tank group are respectively communicated with the first non-flowing water washing tank group, oil removing liquid is arranged in the oil removing tank, chromizing liquid is arranged in the chromizing tank, and the oil removing liquid and the chromizing liquid are compatible with each other;

the water pump is used for pumping water in the spraying groove and the draining groove into the second non-flowing water washing groove set.

Further, the first no-flow rinsing bath group comprises a first no-flow rinsing bath, a second no-flow rinsing bath and a third no-flow rinsing bath which are sequentially communicated, wherein the first no-flow rinsing bath is communicated with the oil removing groove and can supplement water to the oil removing groove; the second no-flow rinsing bath group comprises a No. four no-flow rinsing bath, a No. five no-flow rinsing bath and a No. six no-flow rinsing bath which are sequentially communicated, the No. six no-flow rinsing bath is communicated with the spraying bath and the draining bath through a pump, the No. four no-flow rinsing bath is communicated with the No. three no-flow rinsing bath, and water can be supplemented to the No. three no-flow rinsing bath.

Further, single-way valves are arranged between the first no-flow rinsing bath and the second no-flow rinsing bath, between the second no-flow rinsing bath and the third no-flow rinsing bath, between the fourth no-flow rinsing bath and the fifth no-flow rinsing bath, and between the fifth no-flow rinsing bath and the sixth no-flow rinsing bath; the water flow sequentially passes through a No. six no-flow rinsing bath, a No. five no-flow rinsing bath, a No. four no-flow rinsing bath, a No. three no-flow rinsing bath, a No. two no-flow rinsing bath and a No. one no-flow rinsing bath;

the No. six No. two no.

Further, the control indexes of the deoiling liquid are as follows: 68 wt% nitric acid 40-60 g/L, 50 wt% hydrofluoric acid 5-15 g/L, and acid concentration 1.0-1.5 equivalent.

Furthermore, in the long-term operation process of the oil removing groove, the added agents are solutions of nitric acid and hydrofluoric acid, and 68 wt% of nitric acid/50 wt% of hydrofluoric acid in the added agents of the oil removing groove is 1.5-2.5.

Further, the control indexes of the chromizing liquid are as follows: chromic anhydride CrO32.5-3.5 g/L, 50 wt% hydrofluoric acid 0.4-0.8 g/L, 68 wt% nitric acid 5-7 g/L, pH 1.8.8-2.2.

Furthermore, in the long-term operation process of the chromizing liquid, the added medicament is a solution of nitric acid and hydrofluoric acid, and the added medicament of the chromizing tank is 68 wt% of nitric acid/50 wt% of hydrofluoric acid which is 8-12.

Further, the mutual compatibility of the deoiling liquid and the chromizing liquid means that:

when part of deoiling liquid in the deoiling tank is brought into the chromizing tank, the operation of the chromizing tank is not influenced, and the chromizing capacity of the chromizing liquid is not influenced;

when part of chromizing liquid in the chromizing tank is brought into the oil removing tank, the operation of the oil removing tank is not influenced, and the oil removing capability of the oil removing liquid is not influenced.

The invention has the beneficial effects that: 1. the degreasing liquid adopts a solution of nitric acid and hydrofluoric acid, and stable components are selected to ensure that the degreasing liquid does not generate precipitation after long-term operation, and the surface of the aluminum material is not easy to be coated with ash and is not easy to generate crystallized precipitates.

2. The chromizing liquid adopts a solution of chromic anhydride, hydrofluoric acid and nitric acid, and stable components are selected to ensure that the chromizing liquid does not generate precipitate after long-term operation, and the surface of the aluminum material is not easy to hang ash and generate crystallized precipitates. And the risk of cleaning the tank is avoided by avoiding the generation of sodium fluoroaluminate and potassium fluoroaluminate precipitates and the decomposition of organic matters.

3. Careful selection of the components ensures that the long-term operation of the oil removal bath does not affect the stability of the chromizing bath. The deoiling liquid is compatible with the chromizing liquid, when the deoiling liquid is inevitably carried into the chromizing liquid by the aluminum material, the operation of the chromizing liquid and the chromizing effect of the aluminum material are not influenced, and no precipitation and crystallization exist in the chromizing tank.

4. The stability component that ensures the chromizing cell is compatible with the oil removal cell is carefully selected. The invention firstly focuses on the compatibility of the selected components to the deoiling liquid on the premise of selecting the components of the chromizing liquid, stabilizing the tank liquid and not precipitating and crystallizing.

5. The ratio of the two acids of the oil removal tank additive is carefully selected. The production of the chromizing aluminum material is found in long-term operation that even if the degreasing agent only contains nitric acid and hydrofluoric acid, the tank bottom of the degreasing tank still has the risk of precipitating aluminum fluoride, the cleaning is required regularly, sludge contains extremely toxic fluoride, and the operation is very dangerous. According to the invention, the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the degreasing liquid additive is controlled to be 1.5-2.5, so that the risk of precipitation in the degreasing tank is thoroughly eliminated.

6. The ratio of the two acids of the chromizing vessel charge was carefully selected. The production of the chromizing aluminum material is found in long-term operation that even if the chromizing agent only contains chromic anhydride, nitric acid and hydrofluoric acid, the bottom of a chromizing tank still has the risk of separating out aluminum fluoride and chromium fluoroaluminate, the bottom needs to be cleaned regularly, sludge contains virulent fluoride and hexavalent chromium, and the operation is very dangerous. According to the invention, the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the chromizing liquid additive is controlled to be 8-12, so that the risk of precipitation in the chemical tank is thoroughly eliminated.

7. On the basis of medicament compatibility and bath solution stability, an oil removing groove is arranged for compatibility of a chromizing bath medicament, and a first non-flowing water washing bath group is responsible for intercepting the oil removing liquid and bringing the oil removing liquid into the chromizing bath, so that the medicament is supplemented, and the stability and the chromizing capacity of the chromizing bath are not damaged.

8. On the basis that the medicament is compatible and the tank liquor is stable, the chromizing tank is compatible with the oil removing tank, the second non-flowing water washing tank group is responsible for intercepting the chromizing liquor, the chromizing liquor components are brought into the oil removing tank during reverse water replenishing, and the stability and the oil removing capacity of the oil removing tank are not damaged due to the compatibility of the oil removing liquid and the chromizing liquor.

9. On the basis that the medicament is compatible and the tank liquor is stable, the water pump that will spray in groove and the drop dry tank is gone into the water washing tank group that does not flow and is carried out the moisturizing, can not only make the aluminum product cleaner do benefit to follow-up spraying process, moreover to the clear water make full use of more environmental protection.

10. The invention sets medicament interception and reverse water supplement, skillfully designs the first non-flowing water washing tank group and the second non-flowing water washing tank group, so that cleaning water reversely enters the oil removing tank, thereby not only supplementing the liquid level, but also recovering the medicament. More importantly, the cleaning water of the No. six no-flow rinsing bath is partially updated to form the gradient distribution of the No. four no-flow rinsing bath, the No. five no-flow rinsing bath and the No. six no-flow rinsing bath with high front and low back for intercepting the concentration of the medicament, the medicament concentration distribution of the No. four no-flow rinsing bath, the No. five no-flow rinsing bath and the No. six no-flow rinsing bath brought into the No. four no-flow rinsing bath, the No. five no-flow rinsing bath and the No. six no-flow rinsing bath is reversely supplemented with water to form dynamic balance, and the chromating membrane is; on the basis, the invention realizes zero discharge of waste water and waste residue in spray chromizing treatment.

Drawings

FIG. 1 aluminum ash component detection report;

FIG. 2 shows a source of aluminum-containing waste residues in a large aluminum plant;

FIG. 3 is a flow chart of chromium-containing wastewater treatment;

FIG. 4 shows a nickel-containing wastewater treatment process;

FIG. 5 is a flow of waste water and residue treatment;

FIG. 6 shows a conventional spray chromizing process and slot layout;

FIG. 7 is a schematic structural diagram of a degreasing and chromizing chemical compatible and contamination reduction spray system for aluminum reduction of the present invention.

Wherein: the device comprises an oil removing groove 1, a first non-flowing water washing groove group 2, a chromizing groove 3, a second non-flowing water washing groove group 4, a spraying groove 5, a draining groove 6, a first pump 7, a first non-flowing water washing groove 21, a second non-flowing water washing groove 22, a third non-flowing water washing groove 23, a fourth non-flowing water washing groove 41, a fifth non-flowing water washing groove 42, a sixth non-flowing water washing groove 43, a first single-way valve 01, a second single-way valve 02, a third single-way valve 03, a fourth single-way valve 04, a fifth single-way valve 05, a sixth single-way valve 06, a seventh single-way valve 07, an eighth single-way valve 08, a ninth single-way valve 09, a second pump 9 and a tenth single-way valve 010.

Detailed Description

The invention relates to a spraying system for removing oil and chromizing agents compatible and reducing pollution in aluminum industry, which is a new process created after unprecedented system research is carried out on a spraying pretreatment process with large waste water and waste residue amount and huge environmental protection pressure in the existing aluminum processing enterprises after the production confusion of the aluminum processing enterprises is fully known and the spraying pretreatment process is researched for many years.

Quantitative and qualitative analysis of oil removal and chromizing stabilization and compatible agents.

1. Qualitative and quantitative analysis of each component of deoiling liquid

In the prior art, sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, hydrofluoric acid, sodium fluoride, ammonium bifluoride and a proper amount of surfactant are generally selected to remove oil. The quantitative and qualitative analysis of each component is as follows:

sulfuric acid: the sulfuric acid is a basic component for acidic oil removal, and has the functions of providing an acidity value, dissolving a natural oxidation film and dissolving aluminum. The sulfuric acid is mainly used for maintaining a certain free acidity of the deoiling liquid, keeping the solution stable, promoting the dissolution of aluminum and enabling the aluminum surface to present an active area which is beneficial to the film formation of chromate. The oil removal effect is weakened due to the over-low sulfuric acid content and over-long oil removal time; the concentration of the sulfuric acid is too high, the aluminum dissolution is too fast, and the pressure of wastewater treatment is too large. Therefore, the content of sulfuric acid should be controlled within the range of 10-20 g/L (98% sulfuric acid);

phosphoric acid: phosphoric acid is a basic component for acidic oil removal, has the functions of providing acidity value, dissolving a natural oxidation film and dissolving aluminum, and is a basic component for acidic oil removal. The phosphoric acid is mainly used for maintaining a certain free acidity of the deoiling liquid, keeping the solution stable, promoting the dissolution of aluminum and enabling the aluminum surface to present an active area which is beneficial to the film formation of chromate. The phosphoric acid content is too low, the dissolving capacity is weakened, and the oil removing time is too long; the concentration of phosphoric acid is too high, aluminum is dissolved too fast, aluminum phosphate precipitation risks occur, and the wastewater treatment pressure is too high. Therefore, the content of phosphoric acid should be controlled within the range of 5-15 g/L (85% phosphoric acid);

nitric acid: nitric acid is a basic component for removing oil in an acidic way, and has the functions of providing an acidity value, dissolving a natural oxidation film and dissolving aluminum. The nitric acid is mainly used for maintaining a certain free acidity of the deoiling liquid, keeping the solution stable, promoting the surface of the aluminum to be passivated, removing ash and enabling the surface of the aluminum to present an active area which is beneficial to the film formation of chromate. The content of nitric acid is too low, the passivation capability is weakened, the amount of aluminum dissolved is increased, and the risk of generating aluminum phosphate and aluminum fluoride exists; the concentration of nitric acid is too high, ammonia nitrogen in the wastewater is increased, and the environmental protection treatment pressure is too large. Therefore, the content of the nitric acid is controlled within the range of 20-30 g/L (68% nitric acid);

hydrochloric acid: hydrochloric acid is a basic component for acidic oil removal, and has the functions of providing an acidity value, dissolving a natural oxidation film and dissolving aluminum. The sulfuric acid is mainly used for maintaining a certain free acidity of the deoiling liquid, keeping the solution stable, promoting the dissolution of aluminum and enabling the aluminum surface to present an active area which is beneficial to the film formation of chromate. The hydrochloric acid content is too low, the oil removing time is too long, and the oil removing effect is weakened; the hydrochloric acid concentration is too high, the aluminum dissolution is too fast, the aluminum surface is gray and dark, and the wastewater treatment pressure is too high. Therefore, the content of hydrochloric acid should be controlled within the range of 5-10 g/L (30% hydrochloric acid);

hydrofluoric acid (sodium fluoride, ammonium bifluoride): hydrofluoric acid is an activating agent of the degreasing liquid, quickly dissolves a natural oxide film and aluminum, and is an indispensable promoting component of the degreasing liquid. Hydrofluoric acid is mainly used to maintain a certain free acidity of the solution, keep the solution stable, promote the dissolution of aluminum and complex Al³⁺The aluminum surface is made to exhibit an active zone which is favorable for chromate film formation. F^-And NO3^-Has a certain proportion relation with the content of F^-/NO₃ ^-The optimal ratio range of (A) is 0.25-0.35, and the ratio seriously influences the oil removal effect and the stability of the bath solution. F^-When the content is too low, the oil removal reaction time is longer, and the dissolution on the surface of aluminum is uneven; f^-When the content is too high, the aluminum alloy reacts with aluminum to generate hydrogen violently, the glossiness of the surface of the aluminum profile is reduced, the aluminum dissolving amount is too large, and aluminum fluoride precipitation is easy to occur. Therefore, the content of hydrofluoric acid should be strictly controlled within the range of 5-15 g/L (50% hydrofluoric acid);

surfactant (b): the surfactant is a basic component for acid oil removal, and is used for emulsifying oil stains on the surface of the aluminum material to ensure that the surface is uniform, and the concentration of the surfactant is 0.005-0.010 g/L

Acidity value: the acidity value of the deoiling liquid has obvious influence on the deoiling effect. If the acidity value of the deoiling liquid is low, the dissolution speed of the aluminum alloy is slow, and the deoiling effect is poor; the degreasing liquid has high acidity value, high aluminum alloy dissolving speed and good degreasing effect. Therefore, the acidity value of the deoiling liquid should be strictly controlled within the range of 1.0-1.5 equivalent;

oil removal temperature: the temperature of the degreasing liquid has certain influence on the degreasing effect. When the temperature is lower than 5 ℃, the reaction speed is too slow, and the oil removal effect is weakened; when the temperature is higher than 40 ℃, the film forming speed is too fast, and the aluminum dissolution is too fast. Therefore, the temperature of the degreasing fluid is preferably controlled within the range of 10-30 ℃, and the degreasing fluid can be used at normal temperature under ordinary conditions.

2. Quantitative and qualitative analysis of each component of chromizing tank

In the prior art, the chromizing tank generally contains CrO₃Dichromic acidPotassium K₂Cr₂O₇Sodium fluoride, potassium ferricyanide K₃Fe(CN)₆Sodium silicate Na₂SiO₃Hydrofluoric acid, nitric acid, boric acid, sodium molybdate, a stabilizer (prepared by mixing two organic acids containing carboxyl and hydroxyl), and the like. The quantitative and qualitative analysis of each component is as follows:

chromic anhydride: chromic anhydride is a basic component of passivation, is an oxidizing agent in the chromizing liquid, and has important influence on the forming speed and appearance quality of the chromizing film. When the content of chromic anhydride is too low, the film forming speed is slow, the film is incomplete, the color is light, and the corrosion resistance is reduced; when the content of chromic anhydride is too high, the reaction speed is too high, the film layer is coarse in crystallization, loose and not compact, easy to pulverize, deep in color and luster, poor in binding force, and the environmental pollution and the waste water treatment cost are increased. Therefore, the content of chromic anhydride is controlled to be 1.5-4.0 g/L;

hydrofluoric acid: hydrofluoric acid is an activator for the chromizing liquid, has a catalytic effect on the film-forming reaction, and is an essential accelerating component for forming a chromized film. Hydrofluoric acid is mainly used to maintain a certain free acidity of the solution, keep the solution stable, promote the dissolution of aluminum and complex Al³⁺The aluminum surface is made to exhibit an active zone which is favorable for chromate film formation. F^-In a certain proportion relation with the content of CrO3, F^-/CrO₃The optimal ratio range of (A) is 0.05-0.15, and the size of the ratio seriously influences the adhesiveness and the corrosion resistance of the chromate conversion film. F^-When the content is too low, the film forming reaction time is longer, the film layer is thinner, the corrosion resistance is poor, and even the film can not be formed; f^-When the content is too high, the aluminum alloy reacts with aluminum to generate hydrogen violently, the glossiness of the surface of the aluminum profile is reduced, a film layer is rough and loose, the adhesive force is reduced, meanwhile, the chromizing liquid is unstable, and chromium-containing sludge is easily formed at the bottom of the tank. Therefore, the content of the hydrofluoric acid is strictly controlled within the range of 0.5-1.0 g/L;

nitric acid: nitric acid is a basic component of the chromizing liquid and has the functions of providing an acidity value, dissolving chromized ash, dissolving sludge at the bottom of a chromizing tank, preventing crystallization and oxidizing trivalent chromium. The nitric acid is mainly used for maintaining a certain free acidity of the chromizing liquid, keeping the solution stable, promoting the surface of aluminum to be passivated and ash to make the surface of aluminum present an active area which is beneficial to the film formation of chromate. The content of nitric acid is too low, the dissolving capacity is weakened, the amount of aluminum dissolved is increased, and the risk of generating chromated sludge at the bottom of the tank is generated; the concentration of nitric acid is too high, the chromizing film is too thin, ammonia nitrogen in the wastewater is increased, and the environmental protection treatment pressure is too large. Therefore, the content of the nitric acid is controlled to be within the range of 5-10 g/L (the nitric acid refers to nitric acid with the weight fraction of 68%);

boric acid: boric acid mainly plays a buffering role in the chromizing liquid, so that the pH value of the solution is kept relatively stable. The boric acid can continuously ionize hydrogen ions to supplement the hydrogen ions consumed in the production process, so that the hydrogen ion concentration of the solution is prevented from being sharply reduced, and the solution is prevented from being unstable due to the obvious increase of the pH value of the solution. Meanwhile, boric acid can control the oxidation reaction speed of the solution and improve the appearance of the film layer, so that the conversion film is uniform and compact. The boric acid content is too low, the buffering effect is weak, and the effect is not obvious; the boric acid content is too high, so that the film forming reaction speed is slowed down, and the color of a film layer is lightened. The dosage of the boric acid is preferably 0.3-1.2 g/L;

sodium molybdate: sodium molybdate is an accelerant for forming a chromizing film, has strong oxidizing property in an acid chromate medium, plays a role in accelerating depolarization of a cathode, and improves the current density of the micro battery, thereby accelerating the film forming speed, reducing the reaction temperature and shortening the film forming time. In addition, sodium molybdate also participates in film forming reaction to generate aluminum molybdate compound to be deposited on the chromate film, so that the incompactness of the chromate film is compensated, and the corrosion resistance of the chromate conversion film is improved. The content of sodium molybdate is low, the film forming speed is slow, the film is thin, and the color is light; high content of sodium molybdate, fast film forming speed, deep color, good corrosion resistance, but increased cost. The content of sodium molybdate is controlled within the range of 0.2-0.8 g/L;

a stabilizer: the stabilizer is prepared by mixing two organic acids containing carboxyl and hydroxyl, and has the main function of being mixed with excessive Al³⁺Form stable chelate, control and reduce the film forming reaction speed, mask the interference of impurities in the solution and improve the stability of the chromizing liquid. Meanwhile, the corrosion inhibitor can be adsorbed on the surface of an aluminum matrix through physical and chemical effects, and has higher coverage due to the synergistic effect of the physical and chemical effects, so that the corrosion inhibition effect is improved, and Al is effectively inhibited³⁺The generation of sediment is reduced, and the surface of the workpiece is prevented from being coated with ash. The content of the stabilizer is too low, the chelating effect is poor, and the effect of inhibiting sediments cannot be achieved; too high a content of the stabilizer may prevent the chromizing film-forming reaction from proceeding normally. The content of the stabilizer is generally 0.7-2.5 g/L;

chromizing pH value: the pH value of the chromizing liquid has a remarkable influence on the formation and quality of the chromizing film. If the pH value of the solution is lower, the dissolving speed of the metal is increased, the film forming reaction is accelerated, the film layer is rough and loose, and the adhesive force is poor; if the pH value of the solution is higher, the dissolution speed of the metal is reduced, the film forming reaction is slowed down, the film layer is thinner, the color is light, and the corrosion resistance is poor. Therefore, the pH value of the chromizing liquid is strictly controlled within the range of 1.8-2.2, and nitric acid or ammonia water is generally adopted to adjust the pH value of the chromizing liquid;

chromizing temperature: the solution temperature has a large influence on the performance of the chromized film. When the temperature is lower than 5 ℃, the reaction speed is too slow, the film layer is thin, the color is light, even the film cannot be formed, and the corrosion resistance is poor; when the temperature is higher than 40 ℃, the film forming speed is too fast, the film is rough and loose, powder is easy to generate, and the adhesive force is poor. Therefore, the temperature of the solution is preferably controlled within the range of 20-35 ℃, and the solution can be generally controlled at normal temperature.

And secondly, carrying out quantitative experiments on oil removal and chromizing stability and compatible reagents.

1. Selection scheme for stabilizing oil removing liquid medicament

In the prior art, the acidic degreasing liquid is generally prepared from sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, hydrofluoric acid, sodium fluoride, ammonium bifluoride and a proper amount of surfactant. The medicament component selection scheme is as follows:

selecting the components which are difficult to form dust on the surface of the aluminum material and difficult to generate crystal precipitates: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid and a proper amount of surfactant;

removing components which are easy to form ash on the surface of the aluminum material and easy to generate crystallized precipitates: ammonium fluoride, ammonium bifluoride, sodium fluoride and phosphoric acid. When the acidity value of the bath solution is not enough, acid corrosion ash is easily generated on the surface of the aluminum material, and the oil removal effect is influenced; sodium ions in the sodium fluoride are easy to generate sodium fluoroaluminate precipitate, and the tank liquor needs to be cleaned; phosphoric acid is easy to generate aluminum phosphate precipitate, and tank liquor needs to be cleaned, so from the viewpoint of oil removal effect and tank liquor stability, ammonium fluoride, ammonium bifluoride, sodium fluoride and phosphoric acid are removed from oil removal components.

2. Option for stabilization of chromizing liquid medicament

In the prior art, chromic anhydride (CrO) is generally selected as the chromizing liquid₃) Potassium dichromate (K)₂Cr₂O₇) Sodium fluoride, potassium ferricyanide [ K ]₃Fe(CN)₆]Sodium silicate (Na)₂SiO₃) Hydrofluoric acid, nitric acid, boric acid, sodium molybdate and a stabilizer (prepared and combined by two organic acids containing carboxyl and hydroxyl), wherein the selection scheme of the components of the medicament is as follows:

a. selecting the components which are difficult to form dust on the surface of the aluminum material and difficult to generate crystal precipitates: chromic anhydride, hydrofluoric acid, nitric acid and boric acid;

b. removing components which are easy to form ash on the surface of the aluminum material and easy to generate crystallized precipitates: potassium dichromate, sodium fluoride, potassium ferricyanide, sodium silicate and sodium molybdate. The components contain sodium and potassium, sodium fluoroaluminate and potassium fluoroaluminate precipitates are easy to generate, and a tank needs to be cleaned; meanwhile, the products can make the bath solution unclear, and the chromizing film is easy to be coated with ash, which affects the chromizing quality and should be removed from the chromizing solution components;

c. eliminating unstable and easily oxidized and decomposed components in the chromizing liquid: the stabilizer is prepared and combined by two organic acids containing carboxyl and hydroxyl, which are reducing agent components, are easy to be decomposed by an oxidant in bath solution containing chromic anhydride, hydrofluoric acid, nitric acid and boric acid, influence the stability of the chromating solution and are removed from the chromating solution components.

According to the selection result, the oil removing groove selects sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid and a proper amount of surfactant; chromic acid anhydride, hydrofluoric acid, nitric acid and boric acid are selected as the chromizing tank. These options ensure long-term stability of bath solution without cleaning the bath during degreasing and chromizing.

However, in practical production, after the aluminum material is deoiled, the aluminum material is subjected to two flowing water washes and enters a chromizing tank for chromizing, and partial deoiling liquid may be brought into the chromizing tank to influence the chromizing effect and the stability of the chromizing liquid, even produce precipitates. Therefore, for complete stabilization of the bath solution, a drug compatible design must be made.

3. Selection of components of deoiling liquid compatible with chromizing liquid medicament

The oil removing tank can select stable components of oil removing liquid, such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid and a proper amount of surfactant; the components can bring the aluminum material into the chromizing tank after passing through the oil removing tank and the two flowing rinsing tanks, influence the chromizing capacity and the stability of the chromizing tank, and need to be compatible in design to ensure the long-term stable work of the chromizing tank. The experiments were as follows:

a. the additive amount of the deoiling liquid is 30g/L of 68 wt% nitric acid, 10g/L of concentrated sulfuric acid (weight fraction is 98%), 5g/L of hydrochloric acid solution (weight fraction is 30%), 10g/L of 50 wt% hydrofluoric acid and 0.001g/L of TX-10 phosphate; the addition amount of the chromizing liquid is 3g/L of chromic anhydride, 0.7g/L of 50 wt% hydrofluoric acid, 8.5g/L of 68 wt% nitric acid and 0.8g/L of boric acid. Soaking the aluminum material in degreasing liquid for degreasing for 3 minutes, carrying out two times of 30-second flowing water washing, carrying out chromizing for 3 minutes by using a chromizing liquid, carrying out two times of 30-second flowing water washing, airing, observing the surface color of the aluminum material, and recording the number of an original plate to be 0 #.

The chromizing liquid contains nitric acid and hydrofluoric acid, so that the nitric acid and the hydrofluoric acid in the deoiling liquid can be brought into the chromizing liquid and are completely compatible; but sulfuric acid, hydrochloric acid and TX-10 chromizing liquid in the deoiling liquid do not exist, and a compatible experiment is required to be carried out to observe the influence of the sulfuric acid, the hydrochloric acid and the TX-10 on the working capacity and the stability of the chromizing liquid.

b. Taking out 5 parts of the chromizing liquid in experiment a, and respectively adding 1.0g/L, 2.0g/L, 3.0g/L, 4.0g/L and 5.0g/L of concentrated sulfuric acid (98%); soaking the aluminum material in a degreasing liquid for degreasing for 3 minutes, carrying out two 30-second flowing water washing, carrying out chromizing on the aluminum material by using the 5 parts of chromizing liquid for 3 minutes, carrying out two 30-second flowing water washing, airing, observing the surface color of the aluminum material, recording the numbers 1#, 2#, 3#, 4#, and 5# of the chromizing plates, comparing the appearance colors of the chromizing plates from 0# to 5#, finding that the chromizing plates from 1# to 5# fade, and the chromizing capability is seriously affected by sulfuric acid, wherein even if the concentration of the sulfuric acid is as low as 1g/L, the chromizing film is hardly colored, so that the sulfuric acid in the degreasing liquid is incompatible with the chromizing liquid, and the sulfuric acid component in a degreasing tank is required to be.

c. 5 parts of the chromizing liquid in experiment a are taken out, and 1.0g/L, 2.0g/L, 3.0g/L, 4.0g/L and 5.0g/L of hydrochloric acid solution (30%) are respectively added; soaking the aluminum material in deoiling liquid for 3 minutes, carrying out two 30-second flowing water washing, carrying out chromizing on the aluminum material by using the 5 parts of chromizing liquid for 3 minutes, carrying out 30-second flowing water washing, airing, observing the surface color of the aluminum material, recording the numbers 6#, 7#, 8#, 9# and 10# of the chromizing plates, comparing the appearance colors of the chromizing plates 0 and 5# to 10# of the aluminum material, finding that the 6# to 10# chromizing plates fade, and the chromizing capability is seriously influenced by hydrochloric acid, wherein even if the concentration of the hydrochloric acid is as low as 1g/L, the chromizing film is hardly colored, so that the hydrochloric acid of the deoiling liquid is incompatible with the chromizing liquid, and the components of the hydrochloric acid are required to be removed.

d. Taking out 5 parts of the chromizing liquid in experiment a, and respectively adding TX-100.0001 g/L, 0.0002g/L, 0.0003g/L, 0.0004g/L and 0.0005 g/L; removing oil from the aluminum material in a degreasing liquid for 3 minutes, carrying out two 30-second flowing water washing on the aluminum material, carrying out chromizing on the aluminum material by using the 5 parts of chromizing liquid for 3 minutes, carrying out two 30-second flowing water washing on the aluminum material, airing, observing the surface color of the aluminum material, recording the numbers 11#, 12#, 13#, 14# and 15# of the chromizing plates, and comparing the appearance colors of the chromizing plates 0 and 10-15 #, finding that the chromizing plates 11# to 15# do not fade; after powder spraying and curing, water boiling, cupping and impact detection are carried out, and the result shows that the chromized film has insufficient adhesive force and is unqualified in detection. Therefore, the TX-10 seriously influences the adhesive force of the chromizing film, and even if the concentration is as low as 0.0001g/L, the adhesive force of the chromizing film is not qualified, so that the TX-10 in the deoiling liquid is incompatible with the chromizing liquid, and the surfactant component is removed.

According to the results of experiments a to d, the degreasing fluid can be selected from the components of a chromizing fluid compatible medicament: nitric acid, hydrofluoric acid; other components affect either the stability of the chromizing liquid or the quality of the chromizing film.

4. Selection of components of chromizing liquid compatible with degreasing liquid medicament

e. The addition amount of the deoiling liquid is 40g/L of 68 wt% nitric acid and 10g/L of 50 wt% hydrofluoric acid; the addition amount of the chromizing liquid is 3g/L of chromic anhydride, 0.7g/L of 50 wt% hydrofluoric acid, 8.5g/L of 68 wt% nitric acid and 0.8g/L of boric acid. Removing oil from the aluminum material in deoiling liquid for 3 minutes, performing two times of 30-second flowing water washing, performing chromizing by using a chromizing liquid for 3 minutes, performing two times of 30-second flowing water washing, then drying, observing the surface color of the aluminum material, and recording the number 00# of an original plate.

In order to save water, the aluminum material is cleaned after being chromized, the cleaning water can supplement water for the deoiling liquid, and the cleaning water inevitably contains the chromizing liquid component, so that the deoiling effect is not influenced when the chromizing liquid is compatible with the deoiling liquid. The degreasing liquid contains nitric acid and hydrofluoric acid, so that the nitric acid and the hydrofluoric acid of the chromizing liquid are completely compatible with the degreasing liquid; but chromic anhydride and boric acid deoiling liquid of the chromizing liquid do not exist, and a compatible experiment is needed to observe the influence of the chromic anhydride and the boric acid on the working capacity and stability of the deoiling liquid.

f. 5 parts of the deoiling liquid in experiment e are taken out and CrO is added respectively₃0.2g/L, 0.4g/L, 0.6g/L, 0.8g/L, 1.0 g/L; removing oil from the aluminum material by the 5 parts of deoiling liquid for 3 minutes, carrying out two 30-second flowing water washing, carrying out chromizing by a chromizing liquid for 3 minutes, carrying out two 30-second flowing water washing, airing, observing the surface color of the aluminum material, recording the numbers 16#, 17#, 18#, 19#, and 20# of the chromizing plate, and comparing the appearance colors of the chromizing plate 00# and the chromizing plate 16# to 20# to find that the 16# to 20# of the chromizing plate does not fade; after powder spraying and curing, water boiling, cupping and impact detection are carried out, and the adhesion of the chromizing film is not affected and the detection is qualified. Therefore, CrO is added into the deoiling liquid₃Does not affect the adhesion of the chromized film, CrO₃Is compatible with deoiling liquid.

g. Taking out 5 parts of deoiling liquid in experiment e, and respectively adding 0.1g/L, 0.2g/L, 0.3g/L, 0.4g/L and 0.5g/L of boric acid; removing oil from the 5 parts of deoiling liquid for 3 minutes, carrying out two times of 30-second flowing water washing on the aluminum material, carrying out chromizing on the aluminum material for 3 minutes by using a chromizing liquid, carrying out two times of 30-second flowing water washing on the aluminum material, airing, observing the surface color of the aluminum material, recording the numbers 21#, 22#, 23#, 24#, and 25# of the chromizing plate, and comparing the appearance colors of the chromizing plate 00# and the chromizing plate 21-25 #, wherein the chromizing plate 21-25 # is not faded; after powder spraying and curing, water boiling, cupping and impact detection are carried out, and the adhesion of the chromizing film is not affected and the detection is qualified. Therefore, the boric acid is added into the degreasing liquid, the adhesive force of the chromating film is not influenced, and the boric acid is compatible with the degreasing liquid. However, after the boric acid is added, the oil removing capability is obviously weakened, the reaction speed is reduced, the appearance effect is poor after the aluminum material is subjected to oil removing, and the boric acid can be removed, so that the chromizing liquid is completely compatible with the deoiling liquid.

According to experiments a-g, the compatible selection of the chemical components of the deoiling liquid and the chromizing liquid is as follows:

the deoiling liquid is nitric acid and hydrofluoric acid, and the chromizing liquid is chromic anhydride, nitric acid and hydrofluoric acid. Therefore, national standard detection of various abilities of the chromized film after medicament compatibility is carried out:

h. the addition amount of the deoiling liquid is 40g/L of 68 wt% nitric acid and 10g/L of 50 wt% hydrofluoric acid; the addition amount of chromic anhydride CrO in the chromizing liquid₃3g/L, 50 wt% hydrofluoric acid 0.8g/L, and 68 wt% nitric acid 7 g/L. Removing oil from the aluminum material in deoiling liquid for 3 minutes, performing two times of 30-second flowing water washing, performing chromizing by using a chromizing liquid for 3 minutes, performing two times of 30-second flowing water washing, then drying, observing the surface color of the aluminum material, and recording the number 001# of an original plate.

Observing the appearance color of the chromizing plate 001#, then spraying powder, curing, performing water boiling, cupping and impact detection, and detecting the adhesion of the chromizing film, wherein the result shows that all detection indexes are all qualified.

Although the degreasing liquid only contains nitric acid and hydrofluoric acid, the risk of generating aluminum fluoride precipitate exists, and an appropriate nitric acid/hydrofluoric acid interval needs to be determined, so that the generation of aluminum fluoride is hindered by utilizing the dissolving capacity of nitric acid. The experiments were as follows:

i. the addition amount of the deoiling liquid is 40g/L of 68 wt% nitric acid and 10g/L of 50 wt% hydrofluoric acid; the addition amount of chromic anhydride CrO in the chromizing liquid₃3g/L, 50 wt% hydrofluoric acid 0.7g/L, and 68 wt% nitric acid 8.5 g/L. The aluminum material is degreased for 3 minutes in deoiling liquid, and is respectively subjected to two 30-second flowing water washing, chromizing for 3 minutes in chromizing liquid, and then is respectively subjected to two 30-second flowing water washing. Controlling the acidity value of the degreasing liquid to be 1.0-1.5 equivalent, selecting the weight ratio of 68 wt% nitric acid/50 wt% hydrofluoric acid as the additive liquid to be 1-3: 1, repeating the experiment. Although the chromating film is qualified according to national standard detection, when the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid is low, the reaction is too fast, the dissolved aluminum is too much, and precipitation is separated out in an oil removing groove; the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid is increased, and the precipitate disappears; when the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid is too high, the reaction is slowed down and the oil removal effect is not good. 1 the appropriate addition material for the oil removing liquid has a weight ratio of nitric acid concentration (68%)/50 wt% hydrofluoric acid of 1.5-2.5.

As with the degreasing fluid, although the chromizing fluid only contains chromic anhydride, nitric acid and hydrofluoric acid, there is still a risk of generating aluminum fluoride and chromium fluoroaluminate precipitates, and it is necessary to determine an appropriate nitric acid/hydrofluoric acid interval to utilize the dissolving capacity of nitric acid to hinder the generation of the aluminum fluoride and chromium fluoroaluminate precipitates:

j. the addition amount of the deoiling liquid is 40g/L of 68 wt% nitric acid and 10g/L of 50 wt% hydrofluoric acid; the addition amount of the chromizing liquid is 3g/L of chromic anhydride, 0.7g/L of 50 wt% hydrofluoric acid and 8.5g/L of 68 wt% nitric acid. The aluminum material is degreased in an oil removing groove for 3 minutes, and is subjected to two times of 30-second flowing water washing, chromizing by a chromizing liquid for 3 minutes, and then two times of 30-second flowing water washing. The acidity value of the deoiling liquid is controlled to be 1.0-1.5 equivalent, the concentration of chromic anhydride in the chromizing liquid is controlled to be 2.5-3.5 g/L, and the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid added into the chromizing liquid is 5-15: 1, repeating the experiment. Although the chromating film is qualified according to national standard detection, when the weight ratio of the 68 wt% nitric acid to the 50 wt% hydrofluoric acid is low, chromating is too fast, aluminum fluoride or chromium fluoroaluminate precipitates in a chromating tank, the weight ratio of the 68 wt% nitric acid to the 50 wt% hydrofluoric acid is increased, and the precipitates disappear; when the weight ratio of the 68 wt% nitric acid to the 50 wt% hydrofluoric acid is too high, the color of the chromized film becomes light, the weight of the film becomes light, and the national standard detection of the chromized film is unqualified. The proper weight ratio of the two acids of the additive of the chromizing liquid is 68 wt% nitric acid/50 wt% hydrofluoric acid and is 8-12.

Third, the stability and compatibility of the degreasing liquid and the chromizing liquid medicament are designed and the experimental result is analyzed

According to the experiments a to j and the detection results, the following analysis can be performed:

1. the degreasing liquid is composed of nitric acid and hydrofluoric acid, and the bath liquid is stable and compatible with the chromizing liquid. The weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the additive of the degreasing liquid is controlled to be 1.5-2.5, so that the degreasing liquid can be kept to operate stably for a long time, and aluminum fluoride precipitates are not generated.

2. The components of the chromizing liquid are selected from chromic anhydride, nitric acid and hydrofluoric acid, and the bath liquid is stable and compatible with deoiling liquid. The weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the additive of the chromizing liquid is controlled to be 8-12, so that the long-term stable operation of the degreasing liquid can be maintained, and aluminum fluoride and chromium fluoroaluminate precipitates are not generated.

The technical solution of the present invention is further described below with reference to the accompanying drawings and the detailed description.

The invention provides a degreasing and chromizing agent compatible and pollution-reducing spraying system for slag reduction in aluminum industry, which comprises an oil removing tank 1, a first non-flowing water washing tank group 2, a chromizing tank 3, a second non-flowing water washing tank group 4, a spraying tank 5 and a draining tank 6, wherein aluminum sequentially passes through the oil removing tank 1, the first non-flowing water washing tank group 2, the chromizing tank 3, the second non-flowing water washing tank group 4, the spraying tank 5 and the draining tank 6; the oil removing tank 1 and the second non-flowing water washing tank group 4 are respectively communicated with the first non-flowing water washing tank group 2, oil removing liquid is arranged in the oil removing tank 1, chromizing liquid is arranged in the chromizing tank 3, and the oil removing liquid and the chromizing liquid are compatible with each other;

the water-saving draining device is characterized by further comprising a first pump 7, the spraying groove 5 and the draining groove 6 are communicated with the second non-flowing water washing groove group 4 through the first pump 7 respectively, and the first pump 7 is used for pumping water in the spraying groove 5 and the draining groove 6 into the second non-flowing water washing groove group 4.

The first no-flow rinsing bath 2 group comprises a no-flow rinsing bath 21, a no-flow rinsing bath 22 and a no-flow rinsing bath 23 which are communicated in sequence, the no-flow rinsing bath 21 is communicated with the oil removing groove 1 and can supplement water to the oil removing groove 1; the second no-flow rinsing bath 4 group comprises a No. four no-flow rinsing bath 41, a No. five no-flow rinsing bath 42 and a No. six no-flow rinsing bath 43 which are communicated in sequence, the No. six no-flow rinsing bath 43 is communicated with the spraying bath 5 and the draining bath 6 through a No. one pump 7, and the No. four no-flow rinsing bath 41 is communicated with the No. three no-flow rinsing bath 23 and can supplement water to the No. three no-flow rinsing bath 23.

Single-way valves are arranged between the first no-flow rinsing bath 21 and the second no-flow rinsing bath 22, between the second no-flow rinsing bath 22 and the third no-flow rinsing bath 23, between the fourth no-flow rinsing bath 41 and the fifth no-flow rinsing bath 42, and between the fifth no-flow rinsing bath 42 and the sixth no-flow rinsing bath 43; the water flow sequentially passes through a No. six no-flow rinsing bath 43, a No. five no-flow rinsing bath 42, a No. four no-flow rinsing bath 41, a No. three no-flow rinsing bath 23, a No. two no-flow rinsing bath 22 and a No. one no-flow rinsing bath 21;

the No. six No. 6 No. 5 No. 6 No. 7 pumps through the pipeline is linked together, No. six No. 43 No. 5 No. 6 all is provided with the one-way valve on the pipeline of communicating with No. 7 pump.

The degreasing liquid adopts a solution of nitric acid and hydrofluoric acid, and stable components are selected to ensure that the degreasing liquid does not generate precipitation after long-term operation, and the surface of the aluminum material is not easy to be coated with ash and is not easy to generate crystallized precipitates.

The chromizing liquid adopts a solution of chromic anhydride, hydrofluoric acid and nitric acid, and stable components are selected to ensure that the chromizing liquid does not generate precipitate after long-term operation, and the surface of the aluminum material is not easy to hang ash and generate crystallized precipitates. And the risk of cleaning the tank is avoided by avoiding the generation of sodium fluoroaluminate and potassium fluoroaluminate precipitates and the decomposition of organic matters.

The mutual compatibility of the deoiling liquid and the chromizing liquid means that: when part of deoiling liquid in the deoiling tank is brought into the chromizing tank, the operation of the chromizing tank is not influenced, and the chromizing capacity of the chromizing liquid is not influenced; when part of chromizing liquid in the chromizing tank is brought into the oil removing tank, the operation of the oil removing tank is not influenced, and the oil removing capability of the oil removing liquid is not influenced.

Careful selection of the components ensures that the long-term operation of the oil removal bath does not affect the stability of the chromizing bath. The deoiling liquid is compatible with the chromizing liquid, when the deoiling liquid is inevitably carried into the chromizing liquid by the aluminum material, the operation of the chromizing liquid and the chromizing effect of the aluminum material are not influenced, and no precipitation and crystallization exist in the chromizing tank. The stability component that ensures the chromizing cell is compatible with the oil removal cell is carefully selected. The invention firstly focuses on the compatibility of the selected components to the deoiling liquid on the premise of selecting the components of the chromizing liquid, stabilizing the tank liquid and not precipitating and crystallizing.

On the basis of medicament compatibility and bath solution stability, the oil removing tank 1 is arranged to be compatible with the chromizing tank 3, and the first no-flow water washing tank group 2 is responsible for intercepting the oil removing liquid and bringing the oil removing liquid into the chromizing tank 3, so that the medicament is supplemented, and the stability and the chromizing capacity of the chromizing tank 3 are not damaged. On the basis that the medicament is compatible and the tank liquor is stable, the chromizing tank 3 is arranged to be compatible with the oil removing tank 1, the second non-flowing water washing tank group 4 is responsible for intercepting the chromizing liquor, the chromizing liquor components are brought into the oil removing tank 1 during reverse water replenishing, and the medicament is supplemented, and the stability and the oil removing capacity of the oil removing tank 1 are not damaged due to the compatibility of the oil removing liquid and the chromizing liquor. On the basis of compatibility of medicaments and stability of tank liquor, water in the spray tank 5 and the draining tank 6 is pumped into the second non-flowing water washing tank group 4 for water supplement, so that the aluminum product is cleaner and beneficial to subsequent spraying procedures, and the clear water is fully utilized and is more environment-friendly.

The invention sets medicament interception and reverse water supplement, skillfully designs the first non-flowing water washing tank group 2 and the second non-flowing water washing tank group 3, so that cleaning water reversely enters the oil removing tank 1, thereby not only supplementing the liquid level, but also recovering the medicament. More importantly, the cleaning water of the No. six no-flow rinsing bath 43 is partially updated to form gradient distribution of the concentration of the medicament intercepted by the No. four no-flow rinsing bath 41, the No. five no-flow rinsing bath 42 and the No. six no-flow rinsing bath 43 with high front and low back, and the medicament concentration distribution of the medicament carried into the No. four no-flow rinsing bath 41, the No. five no-flow rinsing bath 42 and the No. six no-flow rinsing bath 43 by the chromizing bath 3 and the reverse water replenishing of the No. six no-flow rinsing bath 43 form dynamic balance to ensure that the chromized film is qualified; on the basis, the invention realizes zero discharge of waste water and waste residue in spray chromizing treatment and water saving in production.

Furthermore, in the long-term operation process of the oil removing groove, the added agents are solutions of nitric acid and hydrofluoric acid, and 68 wt% of nitric acid/50 wt% of hydrofluoric acid in the added agents of the oil removing groove is 1.5-2.5. The ratio of the two acids of the oil removal tank additive is carefully selected. The risk of precipitation generated in the oil removing groove is thoroughly eliminated by controlling the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the oil removing liquid to be 1.5-2.5.

Further, the control indexes of the chromizing liquid are as follows: chromic anhydride CrO32.5-3.5 g/L, 50 wt% hydrofluoric acid 0.4-0.8 g/L, 68 wt% nitric acid 5-7 g/L, pH 1.8.8-2.2. The addition amount of the chromic anhydride is controlled, so that the film layer has enough thickness and enough compactness. The film forming speed is controlled within a reasonable range by controlling the pH value of the chromizing liquid, and the film quality is improved.

Furthermore, in the long-term operation process of the chromizing liquid, the added medicament is a solution of nitric acid and hydrofluoric acid, and the added medicament of the chromizing liquid is 68 wt% of nitric acid/50 wt% of hydrofluoric acid which is 8-12. The ratio of the two acids of the chromizing vessel charge was carefully selected. The risk of precipitation generated in the chemical tank is thoroughly eliminated by controlling the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the additive in the chromizing liquid to be 8-12.

The invention is further illustrated by the following specific examples.

The components of the degreasing solution and the chromizing solution in examples 1 to 5 are shown in the following tables.

In embodiments 1 to 5, a spray system for removing oil and chromizing chemicals compatible with slag reduction in aluminum industry and reducing pollution comprises an oil removal tank 1, a first stagnant water washing tank group 2, a chromizing tank 3, a second stagnant water washing tank group 4, a spray tank 5 and a draining tank 6, wherein an aluminum material sequentially passes through the oil removal tank 1, the first stagnant water washing tank group 2, the chromizing tank 3, the second stagnant water washing tank group 4, the spray tank 5 and the draining tank 6; the oil removing tank 1 and the second non-flowing water washing tank group 4 are respectively communicated with the first non-flowing water washing tank group 2, oil removing liquid is arranged in the oil removing tank 1, chromizing liquid is arranged in the chromizing tank 3, and the oil removing liquid and the chromizing liquid are compatible with each other;

The first no-flow rinsing bath group 2 comprises a no-flow rinsing bath 21, a no-flow rinsing bath 22 and a no-flow rinsing bath 23 which are communicated in sequence, wherein the no-flow rinsing bath 21 is communicated with the oil removing groove 1 and can supplement water to the oil removing groove 1; the second no-flow rinsing bath 4 group comprises a No. four no-flow rinsing bath 41, a No. five no-flow rinsing bath 42 and a No. six no-flow rinsing bath 43 which are communicated in sequence, the No. six no-flow rinsing bath 43 is communicated with the spraying bath 5 and the draining bath 6 through a No. one pump 7, and the No. four no-flow rinsing bath 41 is communicated with the No. three no-flow rinsing bath 23 and can supplement water to the No. three no-flow rinsing bath 23.

A first single-pass valve 01 is arranged on a communication pipeline between the oil removing groove 1 and the first no-flow rinsing bath 21; a second single-way valve 02 is arranged on a communication pipeline between the first no-flow rinsing bath 21 and the second no-flow rinsing bath 22; a third one-way valve 03 is arranged on a communication pipeline between the second no-flow rinsing bath 22 and the third no-flow rinsing bath 23; a fourth one-way valve 04 is arranged on a communication pipeline between the third no-flow rinsing bath 23 and the fourth no-flow rinsing bath 41; a five-way single valve 05 is arranged on a communication pipeline between the four-way no-flow rinsing bath 41 and the five-way no-flow rinsing bath 42; a six-way valve 06 is arranged on a communication pipeline between the five-way no-flow rinsing bath 42 and the six-way no-flow rinsing bath 43.

A seventh one-way valve 07 is arranged on a pipeline between the No. six no-flow rinsing bath 43 and the No. one pump 7; an eight-type one-way valve 08 is arranged on a pipeline between the spraying groove 5 and the first pump 7; a nine-way single valve 09 is arranged on a pipeline between the draining groove 6 and the first pump 7; the spraying groove 5 is also provided with a second pump 9 for supplying water to the spraying groove to realize high-pressure atomization spraying. A ten-way valve 010 is arranged on a pipeline between the second pump 9 and the spraying system of the spraying groove 5.

In examples 1 to 5, the aluminum material treatment processes were all as follows: the aluminum material is deoiled in deoiling liquid of a deoiling tank 1 for 2-4 minutes, is subjected to flowing water washing for 30 seconds respectively through three passages of a first non-flowing water washing tank group 2, is subjected to chromizing in chromizing liquid of a chromizing tank 3 for 2-4 minutes, is subjected to flowing water washing for 30 seconds respectively through three passages of a second non-flowing water washing tank group 4, and is subjected to high-pressure atomization spraying for 30 seconds. And (5) drying the aluminum material in a draining groove 6 for detection. Observing the appearance color of the aluminum product after chromizing, then spraying powder, curing, performing water boiling, cupping and impact detection, and detecting the adhesion of the chromized film, wherein the result shows that all detection indexes are all qualified.

In examples 1 to 5, the acidity values of the degreasing solutions were all within a range of 1.0 to 1.5, and the pH values of the chromating solutions were all within a range of 1.8 to 2.2. When the oil removing tank runs for a long time, the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the additive agent of the oil removing liquid is 1.5-2.5; when the chromizing liquid runs for a long time, the weight ratio of 68 wt% nitric acid to 50 wt% hydrofluoric acid in the additive agent of the chromizing liquid is 8-12.

In examples 1 to 5, the oil removing tank 1 and the chromizing tank 3 were operated for 45 days without precipitation crystallization.

In embodiments 1 to 5, an operation flow of a degreasing and chromizing agent compatible and pollution-reducing spraying system for aluminum industry slag reduction is as follows:

1. the operation process of the oil removing groove 1 to the chromizing groove 3 medicament compatible system is as follows: the aluminum material is subjected to oil removal in the oil removal tank 1 for 2-4 minutes, is subjected to flowing water washing for 30 seconds respectively through three times of the first non-flowing water washing tank group 2, enters the chromizing tank 3, and the medicament in the oil removal tank 1 is brought into the chromizing tank 3, so that the operation flow of the oil removal tank 1 for the medicament compatible system of the chromizing tank 3 is completed;

2. the operation process of the chemical compatible system of the chromizing tank 3 to the oil removing tank 1 is as follows: the aluminum material is chromated in a chromating tank 3 for 2-4 minutes, then is subjected to three flowing water washing steps of a second non-flowing water washing tank group 4 for 30 seconds respectively, is drained, and the chromating liquid is brought into the second non-flowing water washing tank group 4; the valve 44 is opened, water flows through the No. six one-way valve 06, the No. five one-way valve 05, the No. four one-way valve 04, the No. three one-way valve 03, the No. two one-way valve 02 and the No. one-way valve 01 to replenish water to the oil removing groove 1, water containing the chromizing liquid in the chromizing groove 3 enters the oil removing groove 1, and the operation flow of the chromizing groove 3 for the system compatible with the medicament in the oil removing groove 1 is completed;

3. the operation flow of the spraying and draining system is as follows: after the aluminum material is chromized, the aluminum material is subjected to flowing water washing for 30 seconds respectively through three passages of a second non-flowing water washing tank group 4, enters a spraying tank 5, opens a valve 2, starts a second pump 9, and atomizes and sprays the aluminum material for 30 seconds under high pressure; stopping spraying, allowing the aluminum material to enter a draining groove 6, draining the aluminum material, and completing the operation flow of the spraying and draining system;

4. medicament interception and reverse water replenishing system operation flow: starting the first pump 7, enabling the cleaning water in the spraying groove 5 and/or the water in the draining groove 6 to enter the No. six no-flow rinsing groove 43, and reducing the medicament concentration of the No. six no-flow rinsing groove 43; then, the trapped chromizing liquid reversely flows back to a No. three No. 23 No. stagnant water washing tank through a No. six one-way valve 06, a No. five one-way valve 05 and a No. four one-way valve 04; then, water is supplied to the oil removing groove 1 through a third one-way valve 03, a second one-way valve 02 and a first one-way valve 01, the water of the chromizing liquid in the chromizing groove 3 and the deoiling liquid in the oil removing groove 1 flows back to the oil removing groove 1, and the operation process of medicament interception and reverse water supply system is completed.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims

1. A degreasing and chromizing agent compatible and pollution-reducing spraying system for slag reduction in aluminum industry is characterized by comprising an oil removing groove, a first non-flowing water washing groove group, a chromizing groove, a second non-flowing water washing groove group, a spraying groove and a draining groove, wherein aluminum sequentially passes through the oil removing groove, the first non-flowing water washing groove group, the chromizing groove, the second non-flowing water washing groove group, the spraying groove and the draining groove; the oil removing tank and the second non-flowing water washing tank group are respectively communicated with the first non-flowing water washing tank group, oil removing liquid is arranged in the oil removing tank, chromizing liquid is arranged in the chromizing tank, and the oil removing liquid and the chromizing liquid are compatible with each other;

the first pump is used for pumping the water in the spraying tank and the draining tank into the second non-flowing water washing tank group;

the control indexes of the deoiling liquid are as follows: 68 wt% nitric acid 40-60 g/L, 50 wt% hydrofluoric acid 5-15 g/L, acid concentration 1.0-1.5 equivalent;

in the long-term operation process of the oil removing groove, the added medicaments are solutions of nitric acid and hydrofluoric acid, and 68 wt% of nitric acid/50 wt% of hydrofluoric acid in the added medicaments in the oil removing groove is 1.5-2.5;

the control indexes of the chromizing liquid are as follows: chromic anhydride CrO₃2.5-3.5 g/L, 50 wt% hydrofluoric acid 0.4-0.8 g/L, 68 wt% nitric acid 5-7 g/L, pH 1.8.8-2.2;

in the long-term operation process of the chromizing liquid, the added medicament is a solution of nitric acid and hydrofluoric acid, and the added medicament of the chromizing tank is 68 wt% of nitric acid/50 wt% of hydrofluoric acid which is 8-12.

2. The degreasing and chromizing agent compatible and pollution-reducing spraying system for aluminum industry slag reduction according to claim 1, wherein the first no-flow rinsing bath group comprises a no-flow rinsing bath, a no-flow rinsing bath and a no-flow rinsing bath which are sequentially communicated, wherein the no-flow rinsing bath is communicated with the degreasing bath and can supplement water to the degreasing bath;

the second no-flow rinsing bath group comprises a No. four no-flow rinsing bath, a No. five no-flow rinsing bath and a No. six no-flow rinsing bath which are sequentially communicated, the No. six no-flow rinsing bath is communicated with the spraying bath and the draining bath through a pump, the No. four no-flow rinsing bath is communicated with the No. three no-flow rinsing bath, and water can be supplemented to the No. three no-flow rinsing bath.

3. The degreasing and chromizing agent compatible and contamination reduction spray system for aluminum industry slag reduction according to claim 1, wherein single-way valves are arranged between the no-flow rinsing bath and the no-flow rinsing bath, and between the no-flow rinsing bath and the no-flow rinsing bath;

the water flow sequentially passes through a No. six no-flow rinsing bath, a No. five no-flow rinsing bath, a No. four no-flow rinsing bath, a No. three no-flow rinsing bath, a No. two no-flow rinsing bath and a No. one no-flow rinsing bath;

the No. six No. two.

4. The aluminum industry slag reduction oil and chromizing agent compatible and pollution reduction spray system of claim 1, wherein the compatibility of the oil removal liquid and the chromizing liquid is that: