A deep demulsification process for aluminum processing waste emulsion concentrates

Abstract

The present application relates to non-ferrous metal processing wastewater treatment technical field, specifically to a kind of aluminium processing waste emulsion concentrate deep demulsification process, the concentrate is obtained after the evaporation concentration 6~10 times of aluminium processing waste emulsion, the process includes the following steps: S1, the concentrate is transported to demulsification device, with 30~60 r / min stirring rate is gently stirred, so that the concentrate is in homogeneous mixing state;S2, 98% concentrated sulfuric acid is added to demulsification device as demulsifier in dropwise manner, dropwise rate is 0.5~1.0 L / h, and the amount of demulsifier is 0.5%~2.0% of the weight of concentrate.Indirect heating method is used instead of steam aeration in prior art, no additional water is introduced into the reaction system, to avoid the concentrate is diluted by steam.Oil sludge output is reduced to 18%~20% of the volume of concentrate, which is 20%~28% lower than 25% of steam aeration scheme;Completely stratification time is shortened to 5.0 hours, which is 33% shorter than 7.5 hours of steam aeration scheme.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal processing wastewater treatment technology, specifically a deep demulsification process for aluminum processing waste emulsion concentrate. Background Technology

[0002] In the hot rolling process of aluminum processing, a large amount of emulsion is required to achieve roll cooling, workpiece lubrication, and corrosion prevention. After prolonged use, the emulsion ages and deteriorates, forming waste aluminum processing emulsion. This waste emulsion has a complex composition, containing large amounts of mineral oil, surfactants, aluminum powder, metal ions, and other organic impurities, classifying it as a high-concentration, recalcitrant hazardous waste. Currently, the market price for waste-generating companies to outsource transportation and disposal to third parties is generally between 3,000 and 4,000 yuan per ton, placing a significant cost burden on these companies.

[0003] To reduce disposal costs, an increasing number of aluminum processing companies are adopting a process route of "pretreatment → evaporation and concentration → subsequent disposal." Evaporation and concentration can concentrate waste emulsions 6-10 times, significantly reducing their volume. This process can reduce waste liquid volume by 70%-90%, decreasing the amount required for subsequent disposal. However, the concentrated liquid obtained after evaporation and concentration is characterized by high oil content (typically 30%-50%), low water content, high impurity content (6%-10% solids), and high viscosity. Its emulsion system is more stable than the original liquid, with the oil, water, and solid phases tightly bound together. Currently, the industry generally only outsources the disposal of this concentrated liquid as hazardous waste, failing to recover the oil content and resulting in resource waste.

[0004] At the technical level, concentrated sulfuric acid acidification for demulsification has widespread technical recognition in the field of waste emulsion treatment. Studies have shown that concentrated sulfuric acid, as a demulsifier, can effectively disrupt the stability of emulsions, leading to oil-water separation. For hot-rolled waste emulsions from aluminum plants, existing technologies have systematically studied the demulsification effects of heating, acid addition, and combined heating and acid addition processes. In terms of industrial applications, existing aluminum processing waste emulsion treatment systems adopt a process route of "MVR concentration unit → concentrate collection tank → acid addition demulsification unit." The acid addition demulsification unit is equipped with a concentrated sulfuric acid dosing device, clearly disclosing the technical solution of using concentrated sulfuric acid for demulsification after evaporation and concentration of aluminum processing waste emulsions.

[0005] Existing technologies still have significant shortcomings in the deep demulsification and resource recovery of aluminum processing waste emulsion concentrates: (1) In the traditional steam aeration method, some water vapor will condense and enter the concentrate system during heating and stirring, introducing additional water, diluting the concentrate, and reducing the demulsification efficiency. Studies have shown that a high concentration of concentrate is one of the key conditions for ensuring efficient demulsification, and any dilution effect will have an adverse impact on the demulsification effect.

[0006] (2) The stirring intensity is difficult to control precisely. The stirring intensity of steam aeration is greatly affected by the fluctuation of steam pressure and flow rate, making it difficult to achieve precise control of the stirring rate. It is easy to generate a large amount of foam due to excessive stirring, or to cause uneven mixing of demulsifier and concentrate due to insufficient stirring.

[0007] (3) Existing studies mostly target waste emulsion raw materials or general emulsion wastewater. There is a lack of customized process parameter system for the special physical properties (oil content 30%~50%, solid content 6%~10%, high viscosity) of the concentrate obtained after evaporation and concentration of aluminum processing waste emulsion by 6~10 times. This results in high reagent consumption, long reaction cycle and unstable demulsification effect. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the existing defects and provide a deep demulsification process for aluminum processing waste emulsion concentrate. The process uses indirect heating to replace the steam aeration in the prior art, does not introduce additional water into the reaction system, and avoids the concentrate being diluted by steam, which can effectively solve the problems in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a deep demulsification process for aluminum processing waste emulsion concentrate, wherein the concentrate is obtained by evaporating and concentrating aluminum processing waste emulsion 6-10 times, and the process includes the following steps: S1. The concentrate is transported to the demulsifier and gently stirred at a stirring rate of 30~60 r / min to make the concentrate in a uniformly mixed state. S2. Add 98% concentrated sulfuric acid as a demulsifier dropwise into the demulsifier at a rate of 0.5~1.0 L / h. The amount of demulsifier added is 0.5%~2.0% of the weight of the concentrate. As a strong protic acid, concentrated sulfuric acid can effectively neutralize the negative charge on the surface of emulsifier molecules in the concentrate, disrupt the double-layer structure of the oil-water interface, and promote the destabilization and aggregation of the emulsion droplets. Concentrated sulfuric acid contains very little water and will not introduce additional water into the concentrate system. Adding it dropwise avoids violent reactions and foaming caused by excessively high local acid concentrations, ensuring a uniform and stable demulsification reaction.

[0010] S3. The reaction temperature in the demulsifier is controlled at 40~65℃ by indirect heating, with a temperature control accuracy of ±1℃. No additional water is introduced into the reaction system. At the same time, a gentle stirring of 30~60 r / min is maintained so that the demulsifier and the concentrate can carry out the demulsification reaction under uniform mass and heat transfer conditions. S4. Continue the reaction for 3.0 to 7.0 hours until a clear three-phase stratification appears in the demulsifier, with the upper layer being the oil phase, the middle layer being the aqueous phase, and the lower layer being the solid phase. The oil phase shows no obvious emulsification, and the amount of oil sludge produced accounts for 18% to 20% of the volume of the concentrate. S5. Collect the upper oil phase, the middle water phase, and the lower solid phase separately to achieve three-phase separation and resource recovery.

[0011] As a preferred technical solution of the present invention, the preferred range of reaction temperature in step S3 is 55~65℃, and the demulsification efficiency is optimal when the reaction temperature is 60℃; the indirect heating method is heating by a jacketed temperature control device or heating by an external circulation heat exchange device, and the temperature control accuracy is ±1℃.

[0012] As a preferred embodiment of the present invention, the dripping addition in step S2 is achieved by a metering pump or a high-level tank in conjunction with a flow regulating valve, with a dripping rate of 0.6~0.8 L / h and a stirring rate of 40~50 r / min maintained during the dripping process.

[0013] As a preferred embodiment of the present invention, under the conditions of demulsifier dosage of 0.5%~2.0% of the concentrate weight, reaction temperature of 40~65℃, and stirring speed of 30~60 r / min, the sludge yield accounts for 18%~20% of the concentrate volume. In contrast, under the condition of no heating, i.e., room temperature of 25℃, the sludge yield is >30% under the same dosage, and the separation effect is significantly deteriorated. When steam aeration heating and stirring are used instead of indirect heating and gentle stirring, the sludge yield is 25% under the same dosage and temperature conditions, and the time for complete stratification is extended to 7.5 hours.

[0014] As a preferred technical solution of the present invention, step S5 further includes the following resource disposal steps: (a) the collected upper oil phase is dehydrated and refined and then used as base oil for the preparation of rolling emulsion; (b) the collected middle aqueous phase is pH adjusted and biochemically treated and then used for the preparation of workshop emulsion or discharged in compliance with standards; (c) the collected lower solid phase is dehydrated and dried and then used for the recovery of valuable aluminum metals.

[0015] As a preferred technical solution of the present invention, the kinematic viscosity of the base oil recovered in step (a) at 40°C is 40~60 mm² / s and the acid value is ≤0.5 mg KOH / g, which meets the requirements for the reuse of base oil for hot rolling emulsions in aluminum processing.

[0016] As a preferred embodiment of the present invention, the concentrated liquid obtained after evaporation and concentration of the aluminum processing waste emulsion has an oil content of 30% to 50% and a solid content of 6% to 10%.

[0017] As a preferred embodiment of the present invention, the stirring rate of the gentle stirring is 45 r / min, the amount of demulsifier added is 1.2% of the weight of the concentrate, the dropping rate is 0.8 L / h, the reaction temperature is 60℃, the reaction time is 5.0 hours, and the amount of sludge produced accounts for 19% of the volume of the concentrate.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Indirect heating is used instead of steam aeration in existing technologies, which does not introduce additional moisture into the reaction system and avoids dilution of the concentrate by steam. The yield of oily sludge is reduced to 18%~20% of the concentrate volume, which is 20%~28% lower than the 25% of the steam aeration method; the time for complete stratification is shortened to 5.0 hours, which is 33% shorter than the 7.5 hours of the steam aeration method.

[0019] 2. Compared with existing steam aeration schemes that mainly achieve oil-water two-phase separation, this invention achieves clear three-phase stratification of oil, water and solid phases, with clear stratification interfaces, no obvious emulsification in the oil phase, and sufficient sedimentation and separation of impurities in the solid phase.

[0020] 3. The dosage of demulsifier is only 0.5% to 2.0% of the weight of the concentrate, which greatly reduces the cost of reagent procurement and the amount of secondary hazardous waste generated.

[0021] 4. Precise temperature control (±1℃) and gentle mechanical stirring ensure consistent demulsification effects between batches, solving the problem of process instability caused by fluctuations in steam pressure and flow rate in the steam aeration scheme.

[0022] 5. The separated oil phase can be used to recover base oil, the aqueous phase can be reused, and the solid phase can be used to recover valuable aluminum metals, forming a closed-loop treatment model of "demulsification → separation → resource recovery," reducing the hazardous waste disposal costs for aluminum processing enterprises. Taking a typical aluminum processing enterprise as an example, the outsourced disposal cost is calculated at 3,000-4,000 yuan / ton. After adopting this process to achieve resource recovery, considerable hazardous waste disposal costs can be saved annually. At the same time, the recovered oil and aqueous phases can further reduce the enterprise's production raw material costs. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0024] This embodiment addresses the demulsification process performed on a concentrated solution (40% oil content, 8% solids content, and high viscosity) obtained by evaporating and concentrating aluminum processing waste emulsion eight times. The steps outlined are as follows: (1) Feeding and gentle stirring: The concentrate is pumped to the demulsifier and the liquid level is controlled to be 70% of the device volume; the paddle agitator is turned on and the stirring speed is set to 45 r / min for gentle stirring to make the concentrate evenly mixed.

[0025] (2) Add demulsifier: Use 98% concentrated sulfuric acid as demulsifier, and add 1.2% of the weight of the concentrate. Add it by dripping through a metering pump, and control the dripping rate to 0.8 L / h to ensure that the demulsifier is in uniform contact with the concentrate.

[0026] (3) Precise temperature control reaction: Indirect heating is carried out using a jacketed temperature control device to control the reaction temperature at 60℃ with a temperature control accuracy of ±1℃; and a gentle stirring at 45 r / min is maintained continuously.

[0027] (4) Determination of reaction endpoint: After 5.0 hours of continuous reaction, a clear three-phase stratification was observed in the demulsifier, with the upper layer being the oil phase, the middle layer being the water phase, and the lower layer being the solid phase. The oil phase showed no obvious emulsification phenomenon, and the amount of oil sludge produced accounted for 19% of the volume of the concentrate. After standing for 15 minutes, the stratification interface became clearer.

[0028] (5) Separate collection of the three phases: The upper oil phase, the middle aqueous phase, and the lower solid phase are collected separately. The oil phase is dehydrated and refined and then reused as base oil for the preparation of rolling emulsions. The kinematic viscosity of the recovered base oil at 40°C is 45~55 mm² / s, and the acid value is ≤0.3 mg KOH / g. The aqueous phase is pH adjusted and then reused for the preparation of emulsions in the workshop. The solid phase is dehydrated and dried for the recovery of valuable aluminum metals, with an aluminum content of approximately 15%~25%. Example 2

[0029] This example describes a concentrated solution (30% oil content, 6% solids content, high viscosity) obtained by evaporating and concentrating aluminum processing waste emulsion six times: (1) The concentrate is transported to the demulsifier, the liquid level of the concentrate is controlled to be 60% of the volume of the device, and the stirring speed is set to 30 r / min.

[0030] (2) Use 98% concentrated sulfuric acid as a demulsifier, and add it at a rate of 0.5% of the weight of the concentrate; add it dropwise by a metering pump at a rate of 0.5 L / h.

[0031] (3) Indirect heating is carried out using a jacketed temperature control device to control the reaction temperature at 40℃ with a temperature control accuracy of ±1℃, and gentle stirring is maintained at 30 r / min.

[0032] (4) After 7.0 hours of continuous reaction, clear three-phase stratification was achieved, and the amount of oil sludge produced accounted for 18% of the volume of the concentrate.

[0033] (5) Collect the three phases separately as above.

[0034] This embodiment demonstrates that, under conditions of low demulsifier dosage (0.5%) and low heating temperature (40°C), efficient demulsification can still be achieved through the synergistic effect of indirect heating and gentle stirring, with a sludge yield of only 18%. Example 3

[0035] This example describes a concentrated solution (50% oil content, 10% solids content, high viscosity) obtained by evaporating and concentrating aluminum processing waste emulsion 10 times: (1) The concentrate is transported to the demulsifier, the liquid level of the concentrate is controlled to be 70% of the volume of the device, and the stirring speed is set to 60 r / min.

[0036] (2) Use 98% concentrated sulfuric acid as a demulsifier, and add it at a rate of 2.0% of the weight of the concentrate; add it dropwise by a metering pump at a rate of 1.0 L / h.

[0037] (3) Indirect heating is carried out using a jacketed temperature control device to control the reaction temperature at 60℃ with a temperature control accuracy of ±1℃, and gentle stirring is maintained at 60 r / min.

[0038] (4) After a continuous reaction of 3.0 hours, a clear three-phase stratification was achieved, and the amount of sludge produced accounted for 20% of the volume of the concentrate.

[0039] (5) Collect the three phases separately as above.

[0040] This embodiment demonstrates that even for extremely high concentration concentrates with a concentration ratio as high as 10 times and an oil content of 50%, efficient demulsification can be completed in just 3.0 hours under the combined conditions of indirect heating and gentle stirring.

[0041] Comparative Example 1: No indirect heating (room temperature conditions) The same concentrate (8-fold concentrated, 40% oil content, 8% solids content) and demulsifier dosage (1.2%) as in Example 1 were used, but heating was not turned on, and demulsification was carried out at room temperature (25°C) with other conditions remaining the same. The results showed that complete stratification was not achieved after 10 hours of reaction, and the amount of oil sludge produced accounted for 32% of the volume of the concentrate, indicating a significant deterioration in the demulsification effect.

[0042] Comparative Example 2: Simulated Steam Aeration Scheme The same concentrate as in Example 1 (8-fold concentrated, 40% oil content, 8% solids content) and an equivalent amount of sulfuric acid were used as demulsifiers. Following the technical solution in CN118787997A, heating and stirring were performed by introducing steam into the bottom of the reactor, with the reaction temperature controlled at approximately 60°C. Results showed that complete stratification took 7.5 hours, the amount of oil sludge produced accounted for 25% of the concentrate volume, and the stratification effect was only oil-water separation; solid impurities were not fully settled and separated, and there was significant residual emulsification in the oil phase.

[0043] The concentrated sulfuric acid acidification demulsification method involved in this invention utilizes the basic chemical principle of neutralizing the negative charge on the surface of emulsifier molecules in the concentrate to disrupt the double-layer structure at the oil-water interface. The innovative contribution of the process proposed in this invention lies in its ability to address the unique physical properties of the concentrate by synergistically combining three operating parameters: indirect heating, gentle mechanical stirring, and dropwise addition. This achieves clear three-phase stratification and reduces sludge production while replacing steam aeration and avoiding the introduction of additional moisture.

[0044] Compared to conventional understanding of acidification demulsification principles, the three elements in this process are not simply the sum of their individual components. Gentle mechanical stirring (30~60 r / min) ensures uniform distribution of concentrated sulfuric acid in the concentrate and efficient mass transfer, without excessive shearing that would re-emulsify and disperse already aggregated oil droplets, nor generating excessive foam that would affect the layering quality. Indirect, precise temperature control (40~65℃±1℃) provides stable kinetic conditions; appropriately increasing the temperature can reduce the viscosity of the concentrate, enhance molecular thermal motion, promote collisions and interactions between demulsifier molecules and emulsion droplets, and accelerate the demulsification kinetics. However, excessively high temperatures can lead to oxidative deterioration of organic components in the oil phase. The dropwise addition of concentrated sulfuric acid avoids uneven local reactions and violent exothermic reactions. Under the specific conditions of high oil content and high viscosity in the concentrate, these three elements work synergistically to achieve highly efficient demulsification with extremely low demulsifier dosages.

[0045] All parts not disclosed in this invention are prior art, and their specific structures, materials, and working principles will not be described in detail. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deep demulsification process for aluminum processing waste emulsion concentrate, characterized in that, The concentrated solution is obtained by evaporating and concentrating aluminum processing waste emulsion by 6 to 10 times. The process includes the following steps: S1. The concentrate is transported to the demulsifier and gently stirred at a stirring rate of 30~60 r / min to make the concentrate in a uniformly mixed state. S2. Add 98% concentrated sulfuric acid as a demulsifier by dripping into the demulsifier at a rate of 0.5~1.0 L / h, and the amount of demulsifier added is 0.5%~2.0% of the weight of the concentrate. S3. The reaction temperature in the demulsifier is controlled at 40~65℃ by indirect heating, with a temperature control accuracy of ±1℃. No additional water is introduced into the reaction system. At the same time, a gentle stirring of 30~60 r / min is maintained so that the demulsifier and the concentrate can carry out the demulsification reaction under uniform mass and heat transfer conditions. S4. Continue the reaction for 3.0 to 7.0 hours until a clear three-phase stratification appears in the demulsifier, with the upper layer being the oil phase, the middle layer being the aqueous phase, and the lower layer being the solid phase. The oil phase shows no obvious emulsification, and the amount of oil sludge produced accounts for 18% to 20% of the volume of the concentrate. S5. Collect the upper oil phase, the middle water phase, and the lower solid phase respectively.

2. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: The preferred range of reaction temperature in step S3 is 55~65℃, and the demulsification efficiency is optimal when the reaction temperature is 60℃. The indirect heating method is heating with a jacketed temperature control device or heating with an external circulation heat exchange device, and the temperature control accuracy is ±1℃.

3. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: In step S2, the dripping is achieved by a metering pump or a high-level tank in conjunction with a flow regulating valve. The dripping rate is 0.6~0.8 L / h, and the stirring rate is maintained at 40~50 r / min during the dripping process.

4. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: Under the conditions of demulsifier dosage of 0.5%~2.0% of the concentrate weight, reaction temperature of 40~65℃, and stirring speed of 30~60 r / min, the amount of sludge produced accounts for 18%~20% of the concentrate volume.

5. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: Step S5 further includes the following resource recovery steps: (a) the collected upper oil phase is dehydrated and refined and then reused as base oil for the preparation of rolling emulsion; (b) the collected middle aqueous phase is pH adjusted and biochemically treated and then reused for the preparation of workshop emulsion or discharged in compliance with standards; (c) the collected lower solid phase is dehydrated and dried and then used for the recovery of valuable aluminum metals.

6. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 5, characterized in that: The base oil recovered in step (a) has a kinematic viscosity of 40~60 mm² / s at 40°C and an acid value of ≤0.5 mg KOH / g, which meets the requirements for reuse of base oil in hot-rolled emulsions for aluminum processing.

7. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: The concentrated solution obtained after evaporation and concentration of the aluminum processing waste emulsion has an oil content of 30%~50% and a solid content of 6%~10%.

8. The deep demulsification process for aluminum processing waste emulsion concentrate according to claim 1, characterized in that: The stirring rate of the mild stirring is 45 r / min, the amount of demulsifier added is 1.2% of the weight of the concentrate, the dropping rate is 0.8 L / h, the reaction temperature is 60℃, the reaction time is 5.0 hours, and the amount of sludge produced accounts for 19% of the volume of the concentrate.