Method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge

Abstract

The invention relates to the field of resource environmental protection, in particular to a cold rolling magnetic filtration oil sludge self-Fenton demulsification method, which utilizes iron in oil sludge and acid washing waste liquid and acid-containing waste water of a cold rolling plant, and additionally adds a proper amount of hydrogen peroxide and a small amount of bidirectional additive to meet the conditions of Fenton reaction, so as to realize the self-Fenton demulsification of the cold rolling magnetic filtration oil sludge. Conditions are created for respective treatment of oil, water and sludge in subsequent cold-rolled magnetic filtration oil sludge, demulsified oil is recycled, generated precipitated iron sludge serves as a sintering raw material, and demulsified wastewater directly enters a cold-rolled wastewater station for treatment. The method has the advantages that a treatment scheme which is economical, reasonable, short in process and free of secondary pollution is provided for treating the oil sludge in a cold rolling plant, and the field environment-friendly requirement is met; meanwhile, in order to solve the problem that the pH of the mixed solution is difficult to measure due to the fact that a probe of a pH detector is easily wrapped by oil in the mixed solution, a simple mathematical model is established in combination with a material system, and the initial pH value of the mixed solution is conveniently determined and adjusted.

Description

Technical Field

[0001] The present invention relates to the field of resource environmental protection, and particularly to a method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge. Background Art

[0002] During the production process of cold-rolled steel sheets, emulsions need to be sprayed on the rolling mill and the strip steel for lubrication and cooling. Fine particles such as iron-containing materials shed from the strip steel during rolling are mixed into the emulsion. The emulsion is recycled and purified through magnetic filtration and flat-bed filtration. The pollutants adsorbed by magnetic filtration are collected together, namely cold-rolled magnetic filtration oil sludge. This oil sludge generally consists of about 60% oil, 30% water, and 10% iron materials. Among the iron materials, the FeO content is about 62%, and the MFe content is about 13%. The cold-rolled emulsion mainly consists of rolling oil (mainly palm oil), water, emulsifier, antioxidant, oiliness agent, bactericide, etc. Its properties are particularly stable, resulting in the stable properties of the magnetic filtration oil sludge and making it difficult to demulsify. At the same time, at room temperature, the cold-rolled magnetic filtration oil sludge will ferment under the action of bacteria, and the fermented oil sludge becomes more viscous, in a paste state, and has very poor fluidity. The key to treating magnetic filtration oil sludge is to condition it, demulsify it, and destabilize it to achieve the three-phase separation of oil, water, and sludge (iron), and then dispose of the three phases separately. Common oil-containing sludge treatment methods such as solvent extraction method, conditioning-mechanical separation method, high-temperature pyrolysis method, incineration method, etc. are not very adaptable to cold-rolled magnetic filtration oil sludge due to high costs and poor treatment effects.

[0003] The oxidation method uses oxidants to oxidize some macromolecules in the oil sludge into small molecules, which can achieve the demulsification and destabilization of the oil sludge. The Fenton method is a kind of oxidation method. Under acidic conditions, the synergistic effect of hydrogen peroxide and ferrous ions produces ·OH to achieve the purpose of oxidation.

[0004] During the production process of cold-rolled steel sheets, hydrochloric acid is generally used to pickle the steel sheets to remove the surface oxides, and at the same time, pickling waste liquid is generated. After pickling, the steel sheets need to be washed with water to remove the residual hydrochloric acid, generating acid-containing wastewater. The pickling waste liquid is generally treated by a roasting acid regeneration process to produce regenerated hydrochloric acid and iron oxide powder; the acid-containing wastewater is generally neutralized with lime or other alkaline substances, and after the pH index is qualified, it is reused in the factory or discharged.

[0005] In the production process of cold-rolled mills, there are simultaneously magnetic filtration oil sludge wrapped with iron, pickling waste liquid, and acid-containing wastewater, which provides convenient conditions for using the Fenton method to demulsify cold-rolled oil sludge.

[0006] The paper Optimization of Process Conditions for Dehydration of Refinery Wastewater Sludge - Lu Jianping, used chemical oil removal and viscosity reduction - sludge conditioning - centrifugal dehydration process to treat mixed sludge from a refinery's wastewater treatment system. It mainly used the Fenton method to reduce the viscosity of the sludge, and achieved its dehydrated oil separation by adding H2SO4, Fe2SO4, and H2O2. It did not mention the use of existing substances in the sludge to achieve in-situ oxidation reactions.

[0007] The paper Demulsifier Assisted Ultrasonic-Fenton Oxidation Treatment of Oily Scum - Dong Shaoxu, uses demulsifier to pre-demulsify the oil field floating oil scum, and then uses the Fenton method to degrade organic matter. This is different from the idea of ​​this patent that directly uses iron in the sludge to demulsify by self-Fenton method and treat the three phases separately.

[0008] Paper Research on Inorganic Salt-Electro-Fenton Treatment of Emulsified Oily Wastewater - Yin Wenbo, used inorganic salts to treat emulsified oily wastewater, and after demulsification, the oily wastewater was treated with electro-Fenton for oil removal. The treatment object was oily wastewater, and the Fenton method was not used for demulsification.

[0009] The application number is CN202110352321.8, and the patent name is "A method for detecting the oil content in cold-rolled sludge". The detection method is to first add a demulsifier to the cold-rolled sludge sample for demulsification treatment, then add a certain amount of extractant to it for extraction, and then filter the obtained extract to dehydrate and remove the extractant. Finally, the oil content in the sludge is measured by weight method to achieve rapid and accurate determination of the oil content in the cold-rolled sludge. The demulsifier used is concentrated nitric acid or concentrated sulfuric acid. This demulsification method is different from the in-situ self-Fenton method used in this patent.

[0010] The above-mentioned public documents all involve the treatment of oil sludge and oily wastewater, and the Fenton method used therein is obviously different from the in-situ self-Fenton demulsification of the iron contained in the magnetic filtration oil sludge by this patent. Summary of the invention

[0011] The invention aims to provide a method for self-Fenton demulsification of cold-rolled magnetic filtration sludge. At room temperature, the self-Fenton reaction of cold-rolled magnetic filtration sludge is realized by utilizing the iron in the sludge and the pickling waste liquid and acid-containing waste water of the cold rolling mill, and then adding hydrogen peroxide and a bidirectional additive to meet the conditions of the Fenton reaction, thereby achieving the purpose of demulsification; creating conditions for the subsequent three-phase treatment of oil, water and mud of the cold-rolled magnetic filtration sludge, the oil after demulsification is recovered, the generated precipitated iron sludge is used as a sintering raw material, and the waste water after demulsification is directly sent to the cold rolling wastewater station for treatment, so as to provide an economically reasonable, short-process, and secondary pollution-free treatment scheme for the cold rolling mill to treat such sludge, and meet the environmental protection requirements on site; at the same time, in order to solve the problem that the pH detector probe is easily wrapped by the oil in the mixed liquid, resulting in the pH of the mixed liquid being difficult to measure, a simple mathematical model is established in combination with the material system of the invention, so as to facilitate the determination and adjustment of the initial pH value of the mixed liquid.

[0012] To achieve the above object, the present invention is realized through the following technical solutions:

[0013] A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge, specifically comprising the following steps:

[0014] S1. Put the two-way additive into the reaction tank, and then add the cold-rolled magnetic filtration oil sludge to the two-way additive and stir. The mass of the two-way additive is 3% - 5% of the mass of the cold-rolled magnetic filtration oil sludge, the stirring speed is 30 - 60 r / min, and the stirring time is 8 - 10 min;

[0015] S2. Put the pickling waste liquid into the reaction tank and stir. The mass of the pickling waste liquid is 3% - 5% of the mass of the cold-rolled magnetic filtration oil sludge. After stirring for 3 - 5 min, stop stirring and let it stand for 2 - 3 h;

[0016] S3. Put the cold-rolled acid-containing wastewater into the reaction tank and stir. The mass ratio of the cold-rolled magnetic filtration oil sludge to the cold-rolled acid-containing wastewater is 1:(3 - 5), and the stirring speed is 200 - 300 r / min;

[0017] S4. Put the pickling waste liquid into the reaction tank and stir. Adjust the initial pH value of the mixed liquid in the reaction tank, and the range is: 0.5 - 1.0. After stirring for 30 min, adjust the stirring speed to 60 - 80 r / min;

[0018] S5. Divide the hydrogen peroxide into 10 - 12 portions, and add one portion of hydrogen peroxide to the reaction tank every 15 - 20 min. The mass of the hydrogen peroxide is 0.4% - 0.6% of the mass of the cold-rolled magnetic filtration oil sludge; after the addition is completed, stop stirring and let it stand for 8 - 12 h.

[0019] In S1, the two-way additive is waste water ethylene glycol.

[0020] In S3, the pH value range of the cold-rolled acid-containing wastewater is 1 - 3.

[0021] In S2, the mass fraction of HCl in the pickling waste liquid is 8% - 12%, and the Fe 2+ concentration is 110 - 130 g / L.

[0022] In S4, for the initial pH value of the mixed liquid, the calculation formula is as follows:

[0023] Calculated through the following mathematical model:

[0024]

[0025] In formula ①: C is the concentration of HCl in the pickling waste liquid, with the unit of %; m1 is the mass of the pickling waste liquid, with the unit of kg; pH2 is the pH value of the cold-rolled acid-containing wastewater; m2 is the mass of the cold-rolled acid-containing wastewater, with the unit of kg.

[0026] In S5, the concentration range of hydrogen peroxide is 2.8% - 3.2%.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. By using the self-owned materials of the cold rolling production line and the waste water ethylene glycol from the hot rolling mill and the coking plant, only a small part of hydrogen peroxide needs to be purchased to achieve the self-Fenton reaction of cold rolling magnetic filtration sludge;

[0029] 2. The temperature required for demulsification is room temperature, which can effectively reduce energy consumption;

[0030] 3. Make full use of the existing iron in the cold rolling magnetic filtration sludge for the Fenton reaction to reduce the consumption of externally added iron source;

[0031] 4. Introduce additive waste water ethylene glycol to improve the fluidity of cold rolling magnetic filtration sludge and promote its double effects of dispersion in the liquid phase;

[0032] 5. Combine with the existing process treatment unit of the steel enterprise to realize the treatment of cold rolling magnetic filtration sludge, with a simple process and little investment;

[0033] 6. Combine with the invention material system to establish a simple mathematical model to calculate the initial pH value of the mixed liquid, and solve the problem that the pH detector probe is easily wrapped by the oil in the mixed liquid, resulting in difficulty in measuring the pH of the mixed liquid. Brief Description of the Drawings

[0034] Figure 1 It is a process flow chart of the self-Fenton demulsification of cold rolling magnetic filtration sludge. Detailed Embodiments

[0035] The present invention will be described in detail below with reference to the accompanying drawings of the specification, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0036] A method for self-Fenton demulsification of cold rolling magnetic filtration sludge, as shown in Figure 1 , at room temperature, by using the self-owned iron in the sludge and the pickling waste liquid and acid-containing waste water from the cold rolling mill, and then adding an appropriate amount of hydrogen peroxide and a small amount of two-way additive, the conditions for the Fenton reaction are met to achieve the self-Fenton reaction of the cold rolling magnetic filtration sludge, so as to achieve the purpose of demulsification; specifically, it includes the following steps:

[0037] S1. Put the two-way additive into the reaction tank, and then add the cold rolling magnetic filtration sludge into the two-way additive and stir. The mass of the two-way additive is 3% - 5% of the mass of the cold rolling magnetic filtration sludge, the stirring speed is 30 - 60 r / min, and the stirring time is 8 - 10 min;

[0038] The two-way additive is waste glycol. The waste glycol is produced by regularly replacing the hydraulic oil discharged externally by the rolling mills in the hot rolling mill and the locomotives in the coking plant. It can be mixed with water in any proportion and can also act on the cold rolling magnetic filtration sludge, improving the fluidity of the cold rolling magnetic filtration sludge and increasing its dispersion degree in water.

[0039] S2. Put the pickling waste liquid into the reaction tank and stir. The mass of the pickling waste liquid is 3% - 5% of the mass of the cold rolling magnetic filtration sludge. After stirring for 3 - 5 minutes, stop stirring and let it stand for 2 - 3 hours.

[0040] S3. Put the cold rolling acid-containing wastewater into the reaction tank and stir. The mass ratio of the cold rolling magnetic filtration sludge to the cold rolling acid-containing wastewater is 1:(3 - 5); the pH value range of the cold rolling acid-containing wastewater is 1 - 3; the stirring speed is 200 - 300 r / min.

[0041] S4. Put the pickling waste liquid into the reaction tank and stir. Adjust the initial pH value of the mixed liquid in the reaction tank. The initial pH value range is: 0.5 - 1.0. After stirring for 30 minutes, adjust the stirring speed to 60 - 80 r / min; the mass fraction of HCl in the pickling waste liquid is 8% - 12%, and the Fe 2+ concentration is 110 - 130 g / L;

[0042] The initial pH value of the mixed liquid is difficult to detect because there is a lot of oil in the mixed liquid, which is likely to wrap the pH meter probe. Combining with the invention's material system, it is calculated through the following mathematical model:

[0043]

[0044] In mathematical model ①: C is the concentration of HCl in the pickling waste liquid, in units of %; m1 is the mass of the pickling waste liquid, in units of kg; pH2 is the pH value of the cold rolling acid-containing wastewater; m2 is the mass of the cold rolling acid-containing wastewater, in units of kg.

[0045] S5. Divide the hydrogen peroxide into 10 - 12 portions and add one portion of hydrogen peroxide to the reaction tank every 15 - 20 minutes. After the addition is completed, stop stirring and let it stand for 8 - 12 hours; the mass of the hydrogen peroxide is 0.4% - 0.6% of the mass of the cold rolling magnetic filtration sludge, and the concentration range of the hydrogen peroxide is 2.8% - 3.2%.

[0046] The following examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are all conventional methods unless otherwise specified.

[0047] Example 1

[0048] Add 3 kg of the two-way additive into the reaction tank, and then add 100 kg of cold-rolled magnetic filtration oil sludge; turn on the stirring, control the stirring speed at 60 r / min, and stir for 8 min.

[0049] Add 4 kg of pickling waste liquid with 12% mass fraction of HCl into the reaction tank. After stirring for 3 min, stop stirring and let it stand for 2 h.

[0050] Add 500 kg of cold-rolled acid-containing wastewater with pH = 1 into the reaction tank. Turn on the stirring, control the stirring speed at 200 r / min, calculate and supplement a small amount of pickling waste liquid to adjust the initial pH of the mixed liquid in the reaction tank to 0.5; after stirring for 30 min, adjust the stirring speed to 60 r / min.

[0051] Add hydrogen peroxide with a mass fraction of 2.8% into the mixed liquid in 12 batches, 5 kg per batch, with an interval of 20 min each time. After the last addition of hydrogen peroxide, stir for 20 min and then stop stirring, and let it stand for 8 h.

[0052] Example 2

[0053] Add 4 kg of the two-way additive into the reaction tank, and then add 100 kg of cold-rolled magnetic filtration oil sludge. Turn on the stirring, control the stirring speed at 50 r / min, and stir for 9 min.

[0054] Add 3 kg of pickling waste liquid with 10% mass fraction of HCl into the reaction tank. After stirring for 4 min, stop stirring and let it stand for 2 h. Add 400 kg of cold-rolled acid-containing wastewater with pH = 2 into the reaction tank. Turn on the stirring, control the stirring speed at 250 r / min, calculate and supplement a small amount of pickling waste liquid to adjust the initial pH of the mixed liquid in the reaction tank to 1; after stirring for 30 min, adjust the stirring speed to 70 r / min.

[0055] Add hydrogen peroxide with a mass fraction of 3.2% into the mixed liquid in 10 batches, 4 kg per batch, with an interval of 15 min each time. After the last addition of hydrogen peroxide, stir for 15 min and then stop stirring, and let it stand for 10 h.

[0056] Example 3

[0057] Add 5 kg of the two-way additive into the reaction tank, and then add 100 kg of cold-rolled magnetic filtration oil sludge. Turn on the stirring, control the stirring speed at 40 r / min, and stir for 10 min.

[0058] Add 5 kg of pickling waste liquid with 8% mass fraction of HCl into the reaction tank. After stirring for 5 min, stop stirring and let it stand for 2 h.

[0059] Add 300 kg of cold-rolled acid-containing wastewater with pH = 3 into the reaction tank, turn on the stirrer, control the stirring speed at 300 r / min, calculate and supplement a small amount of pickling waste liquid to adjust the initial pH of the mixed liquid in the reaction tank to 0.8. After stirring for 30 min, adjust the stirring speed to 80 r / min.

[0060] Add hydrogen peroxide with a mass fraction of 3.0% to the mixed liquid in 10 batches, 5 kg per batch, with an interval of 18 min each time. After the last addition of hydrogen peroxide, stir for 18 min and then stop stirring, and let it stand for 12 h.

[0061] The present invention utilizes the self-owned materials of the cold-rolling production line and the wastewater ethylene glycol from the hot-rolling mill and the coking plant. Only a small amount of hydrogen peroxide needs to be purchased to realize the self-Fenton reaction of cold-rolled magnetic filtration sludge; the temperature required for demulsification is room temperature, which can effectively reduce energy consumption; the existing iron in the cold-rolled magnetic filtration sludge is fully utilized for the Fenton reaction to reduce the consumption of externally added iron source; the additive wastewater ethylene glycol is introduced to improve the fluidity of the cold-rolled magnetic filtration sludge and promote its dispersion in the liquid phase with a dual effect; combined with the existing process treatment unit of the steel enterprise, the treatment of cold-rolled magnetic filtration sludge is realized, the process is simple and the investment is very small; combined with the material system of the invention, a simple mathematical model is established to calculate the initial pH value of the mixed liquid, solving the problem that the pH detector probe is easily wrapped by the oil in the mixed liquid, resulting in difficulty in measuring the pH of the mixed liquid.

Claims

1. A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge, characterized in that, Specifically, it includes the following steps: S1. Put the two-way additive into the reaction tank, then add the cold-rolled magnetic filtration sludge into the two-way additive and stir. The mass of the two-way additive is 3% - 5% of the mass of the cold-rolled magnetic filtration sludge. The stirring speed is 30 - 60 r / min, and the stirring time is 8 - 10 min; S2. Put the pickling waste liquid into the reaction tank and stir. The mass of the pickling waste liquid is 3% - 5% of the mass of the cold-rolled magnetic filtration sludge. After stirring for 3 - 5 min, stop stirring and let it stand for 2 - 3 h; S3. Put the cold-rolled acid-containing wastewater into the reaction tank and stir. The mass ratio of the cold-rolled magnetic filtration sludge to the cold-rolled acid-containing wastewater is 1:(3 - 5), and the stirring speed is 200 - 300 r / min; S4. Put the pickling waste liquid into the reaction tank and stir. Adjust the initial pH value of the mixed liquid in the reaction tank, and the range is: 0.5 - 1.

0. After stirring for 30 min, adjust the stirring speed to 60 - 80 r / min; S5. Divide the hydrogen peroxide into 10 - 12 portions, and add one portion of hydrogen peroxide to the reaction tank every 15 - 20 min. The mass of the hydrogen peroxide is 0.4% - 0.6% of the mass of the cold-rolled magnetic filtration sludge. After the addition is completed, stop stirring and let it stand for 8 - 12 h.

2. The method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge according to claim 1, characterized in that, In S1, the two-way additive is waste water ethylene glycol.

3. A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge according to claim 1, characterized in that, In S3, the pH value range of the cold-rolled acid-containing wastewater is 1 - 3.

4. A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge according to claim 1, characterized in that, In S2, the mass fraction of HCl in the pickling waste liquid is 8% - 12%, and the Fe 2+ concentration is 110 - 130 g / L.

5. A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge according to claim 1, characterized in that, In S4, the calculation formula for the initial pH value of the mixed liquid is as follows: Calculated by the following mathematical model: In formula ①: C is the concentration of HCl in the pickling waste liquid, with the unit of %; m1 is the mass of the pickling waste liquid, with the unit of kg; pH2 is the pH value of the cold-rolled acid-containing wastewater; m2 is the mass of the cold-rolled acid-containing wastewater, with the unit of kg.

6. A method for self-Fenton demulsification of cold-rolled magnetic filtration oil sludge according to claim 1, characterized in that In S5, the concentration range of the hydrogen peroxide is 2.8% - 3.2%.

Images