A method for regenerating and treating cutting waste liquid of aluminum alloy

Abstract

The present invention discloses a method for regenerating and treating aluminum alloy cutting waste liquid, which includes steps of rough filtration, fine filtration, sterilization, activation, fine filtration and adjustment of the cutting waste liquid; the specific method of activation is: first add concentrated hydrochloric acid to the initial cutting waste liquid after sterilization to adjust the pH value to 5.5 - 6.5, and then add sodium hydroxide to adjust the pH value to 8 - 9.8; the specific method of adjustment is: supplement and add a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid or a mixture of a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid and an extreme pressure agent to the cutting fluid after fine filtration treatment to obtain a new cutting fluid. The present invention solves the problems of reduction or loss of lubrication, rust prevention and other properties of the cutting waste liquid due to the loss of activity of the anionic surfactant, and realizes the efficient reuse of the cutting fluid.

Description

Technical Field

[0001] The present invention relates to the technical field of cutting waste liquid treatment, and more specifically, to a method for regenerating and treating aluminum alloy cutting waste liquid. Background Art

[0002] Cutting fluid plays functions of cooling, lubricating, anti-corrosion and cleaning in the machining of metals. The used cutting fluid contains metal chips, miscellaneous oil, microorganisms, etc., with complex components, and is prone to deterioration, resulting in difficulty in reuse. Moreover, a large amount of initial cutting waste liquid is not easy to treat, which also brings environmental protection problems.

[0003] Furthermore, most of the cutting fluids commonly used in industry are water-based cutting fluids, and water-based cutting fluids mostly use anionic surfactants. After machining aluminum alloy parts, the cutting fluid contains cations such as aluminum ions (Al3+), magnesium ions (Mg2+), iron ions (Fe3+), etc. Some cations will form stearates with anionic surfactants. Such soaps are insoluble in water, resulting in the inactivation of anionic surfactants, and reducing or losing the emulsifying, rust-proof and other properties of the cutting fluid; such cations are also prone to form an emulsified paste layer with floating oil in the cutting fluid, and together with other substances such as dust, microorganisms, impurities, etc., the cutting fluid becomes turbid, further leading to difficulty in reusing the cutting fluid and increasing waste liquid discharge.

[0004] In the prior art, methods such as precipitation, filtration, sterilization, etc. are often used for treating and reusing the waste liquid of cutting fluid. However, due to the inactivation of the surfactant in the cutting fluid, the emulsifying, lubricating, rust-proof, cleaning and other properties of the cutting fluid are significantly reduced. The prior art and treatment methods cannot solve the problem of inactivation of the surfactant in the cutting fluid, and currently there is no technical solution that can improve the performance of cutting waste liquid and achieve reuse. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and provide a method for regenerating and treating aluminum alloy cutting waste liquid, which solves the problems of reduction or loss of properties such as lubrication and rust prevention caused by the loss of activity of anionic surfactants in the cutting waste liquid, and realizes the efficient reuse of the cutting fluid.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A method for regenerating and treating aluminum alloy cutting waste liquid includes steps of rough filtration, fine filtration, sterilization, activation, fine filtration, and adjustment of the cutting waste liquid;

[0008] The specific method of activation is: first add concentrated hydrochloric acid to the initial cutting waste liquid after sterilization to adjust the pH value to 5.5 - 6.5, and then add sodium hydroxide to adjust the pH value to 8 - 9.8;

[0009] The specific adjustment method is as follows: supplement and add a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid or a mixture of a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid and an extreme pressure agent to the cutting fluid after fine filtration treatment to obtain a new cutting fluid.

[0010] Further, the non-ionic surfactant is at least one of maleic anhydride rosin triethanol ester, triethanolamine oleate, non-ionic surfactant 607, and water-soluble polyether ester.

[0011] Further, the specific rough filtration method is as follows: let the initial cutting waste liquid after cutting processing stand for sedimentation, separate the sediment and then filter it to remove particles with a particle size greater than 1500 μm in the waste liquid.

[0012] Further, the specific fine filtration method is as follows: fine filter the cutting fluid after rough filtration through non-woven fabric to filter out the sediment and particles with a size of 20 - 1500 μm in the cutting fluid.

[0013] Further, the specific sterilization method is as follows: perform ozone and UV ultraviolet light sterilization treatment on the initial cutting waste liquid after fine filtration for 2.5 - 3.5 hours.

[0014] Further, the specific fine filtration method is as follows: perform centrifugal separation and fine filtration on the activated cutting fluid to filter out particles larger than 5 μm in the cutting fluid.

[0015] Further, the initial cutting waste liquid is formed after cutting processing of a cutting fluid containing an anionic surfactant, and it contains 10 - 50 wt% of base oil and 10 - 20 wt% of additives.

[0016] Further, the base oil is mineral oil, and the additives are a mixture of extreme pressure agent, rust inhibitor, coolant, anionic surfactant, bactericide, and defoamer.

[0017] The beneficial effects of the present invention are as follows:

[0018] Through rough filtration, fine filtration, sterilization, activation, fine filtration, and adjustment treatment of the cutting waste liquid, a new cutting fluid with good lubricity, stability, and rust prevention performance is obtained, solving the problem of reduced or lost lubrication, rust prevention, and other performance caused by the loss of activity of the anionic surfactant in the cutting waste liquid, realizing the efficient reuse of the cutting fluid, and can be widely applied to the regeneration treatment of various cutting waste liquids. Specific Embodiments

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The method for regenerating and treating the waste liquid from aluminum alloy cutting includes the steps of coarse filtration, fine filtration, sterilization, activation, fine filtration, and adjustment.

[0021] (a) The specific method of coarse filtration is as follows: Inject the initial cutting waste liquid after cutting processing into a precipitation tank for static precipitation to separate impurities such as debris precipitates, and then filter the cutting waste liquid through a 200-mesh filter screen to remove particles with a particle size greater than 1500 μm in the waste liquid.

[0022] The initial cutting waste liquid is formed after cutting processing of a cutting fluid containing an anionic surfactant, and it contains 10 - 50 wt% of base oil and 10 - 20 wt% of additives; the base oil is mineral oil, and the additives are a mixture of extreme pressure agent, rust inhibitor, coolant, anionic surfactant, bactericide, and defoamer.

[0023] The anionic surfactant is selected from at least one of higher fatty acid salts (such as fatty acid methyl ester sulfonate, triethanolamine stearate, etc.), sulfated compounds (such as sodium dodecyl sulfate, sodium polyoxyethylene lauryl ether sulfate, etc.), and sulfonated compounds (sodium dodecyl sulfonate, etc.).

[0024] (b) The specific method of fine filtration is as follows: Fine-filter the cutting fluid after coarse filtration through a non-woven fabric filter to filter out the precipitates and particles with a size of 20 - 1500 μm in the cutting fluid.

[0025] (c) The specific method of sterilization is as follows: Inject the initial cutting waste liquid after fine filtration into a sterilization tank for 2.5 - 3.5 hours of ozone and UV ultraviolet light sterilization treatment to remove microorganisms such as anaerobic bacteria and facultative anaerobic bacteria in the cutting fluid; after sterilization is completed, measure the pH value of the cutting waste liquid; a three-way pipe is installed at the top of the sterilization tank, and the three-way pipe is a straight three-way or an inclined three-way. Its main pipe extends into the sterilization tank, and a dry adsorption package is set at the outlet of the branch pipe, which can dry the gas and adsorb the odor during the aeration process.

[0026] (d) The specific method of activation is as follows: Add concentrated hydrochloric acid to the initial cutting waste liquid after sterilization, stir and mix evenly, adjust the pH value to 5.5 - 6.5, then add sodium hydroxide, stir and mix evenly, and adjust the pH value to 8 - 9.8.

[0027] The addition amount of concentrated hydrochloric acid is calculated according to the following formula: In the formula, V 1 is the volume of hydrochloric acid to be added, with the unit of L; a is the concentration of hydrochloric acid, with the unit of mol / L; V is the volume of the initial cutting waste liquid after sterilization.

[0028] The addition amount of sodium hydroxide is calculated based on the pH value, the volume of the cutting waste liquid, and the concentration of sodium hydroxide before and after adding sodium hydroxide to the cutting waste liquid; the measurement method of the addition amount of sodium hydroxide is the same as that of adding hydrochloric acid.

[0029] In this operation, concentrated hydrochloric acid and sodium hydroxide are both added to the sterilization tank through a three-way pipe; hydrochloric acid can undergo a neutralization reaction with alkaline substances in the cutting waste liquid, and a displacement reaction with aluminum, magnesium, etc., forming chloride salts such as aluminum ions, magnesium ions, and calcium ions); sodium hydroxide can neutralize hydrochloric acid in the cutting waste liquid and undergo a neutralization reaction with carboxylic acid compounds therein, generating carboxylate anions (R-COO - ), forming an oil-in-water molecular structure again, improving the surface activity of the cutting fluid, and sodium hydroxide can chemically react with aluminum salts, magnesium salts, etc. in the cutting waste liquid, converting the original aluminum ions (Al 3+ ), magnesium ions (Mg 2+ ), iron ions (Fe 3+ ) and other cations into precipitates such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide and removing them.

[0030] (e) The specific method of fine filtration is as follows: Use a centrifugal separator to perform centrifugal separation and fine filtration on the activated cutting fluid, and filter out particles larger than 5 μm in the cutting fluid.

[0031] (f) The specific method of adjustment is as follows: Inject the cutting fluid after fine filtration treatment into an adjustment tank, and supplement and add a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid or a mixture of a non-ionic surfactant accounting for 1.5 - 6% of the weight of the cutting fluid and an extreme pressure agent (the extreme pressure agent is preferably bis(dimethylamino)phosphoric acid cardanol ester, and the synthesis method can be referred to the paper: Synthesis and Tribological Properties of Bis(dimethylamino)phosphoric Acid Cardanol Ester Type Antiwear Extreme Pressure Agent [J]. Wei Kecheng; Chen Xiaowei. Synthetic Lubricants, Vol. 47, No. 3, 2020), stir and mix evenly to obtain a new cutting fluid; the non-ionic surfactant is selected from at least one of maleic anhydride rosin triethanol ester, oleic acid triethanolamine, non-ionic surfactant 607 (purchased from Sichuan Ruikai Bang Chemical Materials Co., Ltd.), and water-soluble polyether ester.

[0032] The preferred embodiments are as follows:

[0033] Example 1

[0034] (a) Coarse filtration: The initial cutting waste liquid after cutting processing is injected into a precipitation tank for static precipitation to separate impurities such as debris. Then, the cutting waste liquid is filtered through a 200-mesh filter screen to remove particles with a particle size greater than 1500 μm in the waste liquid. The initial cutting waste liquid is formed after cutting processing with a cutting fluid containing an anionic surfactant (the cutting fluid contains the following components in mass percentage: 40% mineral oil, 5% phosphate ester, 2% diethanolamine, 1% ethylene glycol, 2% sodium dodecylbenzenesulfonate, 1% benzisothiazolinone, 0.5% polypropylene glycol, 48.5% water).

[0035] (b) Fine filtration: The cutting fluid after coarse filtration is finely filtered through a non-woven fabric filter to filter out precipitates and particles with a size of 20 - 1500 μm in the cutting fluid.

[0036] (c) Sterilization The specific method is: Inject the initial cutting waste liquid after fine filtration into a sterilization tank and conduct ozone and UV ultraviolet light sterilization treatment for 3 hours to remove microorganisms such as anaerobic bacteria and facultative anaerobic bacteria in the cutting fluid; after completing sterilization, measure the pH value of the cutting waste liquid.

[0037] (d) Activation The specific method is: Add concentrated hydrochloric acid to the initial cutting waste liquid after sterilization, stir for 0.5 h, adjust the pH value to 6, then add sodium hydroxide, stir for 0.5 h, and adjust the pH value to 8.

[0038] (e) Fine filtration The specific method is: Use a centrifugal separator to conduct centrifugal separation and fine filtration on the activated cutting fluid to filter out particles larger than 5 μm in the cutting fluid.

[0039] (f) Adjustment The specific method is: Inject the cutting fluid after fine filtration treatment into an adjustment tank, add a non-ionic surfactant (2.5% maleic anhydride rosin triethanol ester, 2.5% triethanolamine oleate) accounting for 5% of the weight of the cutting fluid to the adjustment tank, stir and mix evenly to obtain a new cutting fluid.

[0040] Example 2

[0041] Regenerate and treat the aluminum alloy cutting waste liquid according to the method of Example 1, the difference is that: in step (f), add triethanolamine oleate accounting for 2.5% of the weight of the cutting fluid and 2.5% of the non-ionic surfactant 607 to the cutting fluid after fine filtration treatment.

[0042] Example 3

[0043] Regenerate and treat the aluminum alloy cutting waste liquid according to the method of Example 1, the difference is that: in step (f), add triethanolamine oleate accounting for 2.5% of the weight of the cutting fluid and bis(dimethylamino)phosphoric acid cardanol ester accounting for 2.5% of the weight of the cutting fluid to the cutting fluid after fine filtration treatment.

[0044] Example 4

[0045] The aluminum alloy cutting waste liquid was regenerated and treated according to the method of Example 1, except that in step (f), a non-ionic surfactant 607 accounting for 2.5% of the weight of the cutting fluid and bis(dimethylamino)phosphoric acid cardanol ester accounting for 2.5% of the weight of the cutting fluid were added to the cutting fluid after fine filtration treatment.

[0046] Sodium dodecylbenzenesulfonate in Examples 1 - 4 belongs to an anionic surfactant. During the cutting process of the cutting fluid containing this anionic surfactant, negatively charged alkyl sulfonate ions are ionized in the solution and adsorbed on the surface of positively charged aluminum ions through electrostatic action, that is, an adsorption mode with the hydrophilic group facing the aluminum surface and the hydrophobic group facing the aluminum medium is formed. The anionic surfactant has adsorption loss with the surface of the aluminum alloy component; as cations such as aluminum ions and magnesium ions in the cutting fluid increase, the anionic surfactant loses its activity. After the cutting waste liquid is subjected to coarse filtration, fine filtration, and sterilization treatment, hydrochloric acid is added to the cutting waste liquid. Sodium dodecylbenzenesulfonate reacts with hydrochloric acid to form dodecylbenzenesulfonic acid and sodium chloride. At the same time, hydrochloric acid reacts with aluminum, magnesium, etc. in the solution to form chlorides such as aluminum chloride and magnesium chloride. After adding sodium hydroxide solution subsequently, these chlorides such as aluminum chloride and magnesium chloride form precipitates and are removed by filtration. And dodecylbenzenesulfonic acid and sodium hydroxide undergo an acid-base neutralization reaction to form sodium dodecylbenzenesulfonate, making the anionic surfactant regain its activity.

[0047] The performance of the new cutting fluids obtained in Examples 1 - 4 was tested, and the results are shown in Table 1. It can be seen that after the non-ionic surfactant 607 and bis(dimethylamino)phosphoric acid cardanol ester are compounded, a synergistic effect is exerted between the non-ionic surfactant 607 and bis(dimethylamino)phosphoric acid cardanol ester. The cutting fluid has better lubricity, stability, and circulation life, and can further improve the cutting accuracy.

[0048] Table 1

[0049]

[0050] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and retouches without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A method for regenerating aluminum alloy cutting waste liquid, characterized in that: It includes the steps of coarse filtration, fine filtration, sterilization, activation, fine filtration and adjustment of the cutting waste fluid; The specific activation method is: firstly, concentrated hydrochloric acid is added to the sterilized initial cutting waste liquid to adjust the pH value to 5.5-6.5, and then sodium hydroxide is added to adjust the pH value to 8-9.8; the initial cutting waste liquid is formed by cutting the cutting fluid containing anionic surfactant, which contains 10-50wt% of base oil and 10-20wt% of additives; wherein the anionic surfactant is at least one of fatty acid methyl ester sulfonate, triethanolamine stearate, sodium dodecyl sulfate, sodium salt of polyoxyethylene lauryl alcohol ether sulfate, and sodium dodecyl sulfonate; The specific adjustment method is: to the cutting fluid after fine filtration, add a mixture of non-ionic surfactant 607 and extreme pressure agent bis(dimethylamino) cardanol phosphate accounting for 1.5-6% of the weight of the cutting fluid to obtain a new cutting fluid.

2. The method for regenerating aluminum alloy cutting waste fluid according to claim 1, characterized in that: The specific method of coarse filtration is: the initial cutting waste liquid after cutting processing is allowed to settle, the precipitate is separated and then filtered to remove particles with a particle size greater than 1500 μm in the waste liquid.

3. The method for regenerating aluminum alloy cutting waste fluid according to claim 1, characterized in that: The specific method of fine filtration is: the cutting fluid after coarse filtration is finely filtered through non-woven fabric to filter out the sediment and particles with a size of 20-1500μm in the cutting fluid.

4. The method for regenerating aluminum alloy cutting waste fluid according to claim 1, characterized in that: The specific sterilization method is: subjecting the finely filtered initial cutting waste liquid to ozone and UV ultraviolet light sterilization for 2.5-3.5 hours.

5. The method for regenerating aluminum alloy cutting waste fluid according to claim 1, characterized in that: The specific method of fine filtration is: centrifuge the activated cutting fluid for fine filtration to remove particles larger than 5μm in the cutting fluid.

6. The method for regenerating aluminum alloy cutting waste fluid according to claim 1, characterized in that: The base oil is mineral oil, and the additives are a mixture of extreme pressure agent, rust inhibitor, coolant, anionic surfactant, bactericide and defoaming agent.

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