Waste paint liquid regeneration treatment process

Abstract

The invention provides a waste paint liquid regeneration treatment process. The waste paint liquid regeneration treatment process comprises the following steps that S1, waste paint liquid is conveyed to a settling tank through a pump, after standing in the settling tank, the waste paint liquid forms supernate and an impurity layer, the impurity layer is discharged through a lower discharging opening, and the supernate is conveyed to an evaporation recovery unit through the pump; s2, pumping the waste paint liquid from the settling tank to an evaporation kettle, opening a steam pipeline to heat the evaporation kettle, and setting proper evaporation temperature and evaporation duration; according to the waste paint liquid regeneration treatment process provided by the invention, the temperature of the evaporation kettle is accurately regulated and controlled by the steam pipeline proportioning valve, different working condition requirements are met in cooperation with flexibly-adjusted evaporation parameters, the process supports diversified adjustment such as feeding mode replacement, setting of the settling tank as required and negative pressure evaporation, the adaptability is high, and the cost is low. The process is excellent in waste paint liquid treatment capacity, no useless waste is discharged in the whole process, the waste paint liquid recycling rate is greatly increased, and economic and environment-friendly values are both achieved.

Description

Technical Field

[0001] This invention relates to the field of waste paint recycling technology, and in particular to a waste paint recycling process. Background Technology

[0002] Waste paint liquid refers to waste liquid paint and mixed waste liquid generated during paint production, painting application, equipment cleaning, etc. It includes uncured paint, thinner, resin, pigment, solvent and cleaning wastewater, etc. It is mostly volatile, flammable and toxic, and contains harmful components such as benzene and esters. It is classified as hazardous waste. Random discharge will pollute the soil, water sources and atmosphere, and endanger human health. It must be collected, stored and disposed of in accordance with hazardous waste regulations.

[0003] Waste paint recycling is a process that addresses waste paint generated during painting and paint production. Through physical and chemical processes to remove impurities, excess solvents, pigment particles, and harmful components, it separates, purifies, and re-formulates usable resins and effective film-forming substances to bring the paint back to a usable standard. This technology reduces hazardous waste emissions and environmental pollution while also recovering effective raw materials for recycling, offering both environmental and economic benefits. It is an important technological means for green production in the painting industry.

[0004] The existing recycling process involves distilling waste paint to recover some of the organic solvents, but the residue cannot be utilized, which inevitably leads to waste. Furthermore, the lack of a pretreatment unit at the front end means that impurities in the waste paint cannot be effectively filtered and removed, thus affecting the stability of product quality.

[0005] Therefore, it is necessary to provide a waste paint recycling process to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a waste paint recycling process that solves the problems of existing recycling processes that only distill and recover organic solvent residues, resulting in waste and the lack of a pretreatment unit, which makes it difficult to remove impurities and affects product quality stability.

[0007] To solve the above-mentioned technical problems, the waste paint recycling process provided by the present invention includes the following steps: S1: Waste paint is pumped to a settling tank. After settling in the settling tank, the waste paint forms a supernatant and an impurity layer. The impurity layer is discharged through the lower discharge port, and the supernatant is pumped to the evaporation and recovery unit. S2: Waste paint from the settling tank is pumped to the evaporator. The steam pipeline is turned on to heat the evaporator. The appropriate evaporation temperature and evaporation time are set. The gas volatilized during the evaporation process is condensed into liquid by the condenser and flows by gravity to the receiving tank. At the same time, organic solvent is added and stirred evenly to form paint thinner. Then it is discharged into the ton container through the drain port. S3: After the materials participating in the reaction in the evaporation kettle are cooled, they are transferred to the dispersion kettle by a transfer pump. At the same time, solvent is added to the dispersion kettle and mixed and stirred evenly. The dispersed and stirred materials are then transferred to a sand mill for grinding to process the paint particles to a finer level, thereby improving the specific surface area, adhesion and other properties of the paint. The semi-finished paint after sand milling is sent to a regulating and mixing tank and then filled and packaged by a filling machine. S1 constitutes the pretreatment and feeding unit, S2 constitutes the evaporation and recovery unit, and S3 constitutes the industrial paint regeneration unit. The size of the settling tank can be set according to the market material conditions. If the waste paint is relatively clean and free of impurities, a settling tank may not be required.

[0008] Preferably, the waste paint recycling process is controlled by a PLC and operates intermittently. During intermittent operation, the processing frequency is 2 times / day, and the amount of waste paint liquid processed in a single operation is 4t. PLC control enables local control of the equipment and remote control from the central control room. The temperature of the evaporator is regulated by a proportional regulating valve in the steam pipeline. The evaporation temperature and evaporation time are determined based on laboratory test data.

[0009] Preferably, the filling machine is equipped with a weighing instrument for weighing and measuring the semi-finished paint.

[0010] Preferably, the waste paint recycling process is characterized in that, in step S2, a vacuum unit is used to better evaporate volatile materials, and the evaporation system is operated under negative pressure. The evaporation system, operated under negative pressure by a vacuum unit, can effectively lower the boiling point of volatile materials in waste paint, making them more easily and fully evaporated, improving the evaporation efficiency and recovery rate of organic solvents. At the same time, it reduces the heating temperature required for evaporation, reduces the heat loss of effective components in the paint, ensures the quality of subsequent reactor residue regeneration, and optimizes the overall evaporation and recovery process.

[0011] Preferably, in step S3, pigment powder is added to appropriately change the color of the recycled paint; Adding pigment powder to the industrial paint recycling unit to adjust the color of the recycled paint allows for the formulation of different colors of recycled industrial paint as needed, enriching the product range, adapting to diverse application scenarios and customer needs, improving the market adaptability and use value of recycled paint, and at the same time covering the original impurities of the reactor residue, optimizing the appearance quality of the recycled paint, and further improving the comprehensive benefits of waste paint resource utilization.

[0012] Preferably, the pump used in S1 can be a diaphragm pump, a centrifugal pump, or a screw pump.

[0013] Preferably, during the intermittent operation, the evaporation time of each batch of material in the evaporator is 1-3 hours, and the cooling time of the material after evaporation is 2-4 hours.

[0014] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: By setting up a settling tank as a pretreatment and feeding unit, waste paint liquid is subjected to static settling treatment, effectively separating impurities such as crystalline particles and gravel from the paint liquid. This removes adverse factors affecting product quality from the source, significantly improving the purity and quality stability of subsequent recycled products. It solves the problem of product quality fluctuations caused by the lack of pretreatment in traditional processes. The evaporation and recovery unit relies on the coordinated operation of the evaporation kettle, condenser, and receiving tank to achieve efficient recovery of organic solvents from waste paint liquid. The recovered solvents are then compounded into paint thinners, realizing the recycling of organic solvents and avoiding resource waste. This process utilizes the residue generated in the evaporation kettle, which is further processed by an industrial paint regeneration unit consisting of a dispersion kettle, sand mill, regulating and stirring tank, and filling machine. This process disperses and grinds the paint to refine its particle size, increasing its specific surface area and adhesion, ultimately producing qualified recycled industrial paint. This completely solves the resource waste problem caused by the unusable residue and direct discharge of waste paint from traditional processes, maximizing the utilization value of waste paint. Equipped with a PLC control unit, it enables both local and remote control. Combined with a proportional regulating valve in the steam pipeline, it precisely controls the temperature of the evaporator. With flexibly adjustable evaporation parameters, it adapts to different operating conditions. The process supports various adjustments such as changing the feeding method, setting up a settling tank as needed, and negative pressure evaporation, demonstrating strong adaptability. This process excels in waste paint processing capacity, with no useless waste discharged throughout the process, significantly improving the resource utilization rate of waste paint and possessing both economic and environmental value. Attached Figure Description

[0015] Figure 1 A flow chart of the waste paint recycling process provided by the present invention. Figure 2 A schematic diagram of the settling tank is provided for this invention.

[0016] The following are labeled in the diagram: 1. Settling tank, 2. Evaporator, 3. Condenser, 4. Receiving tank, 5. Dispersing tank, 6. Sand mill, 7. Adjusting and mixing tank, 8. Filling machine. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. Example

[0018] In the waste paint recycling process, the waste paint is transported to settling tank 1 by a diaphragm pump. After settling in settling tank 1, the waste paint forms a supernatant and an impurity layer. The impurity layer is discharged through the lower discharge port, and the supernatant is transported to the evaporation and recovery unit by a pump.

[0019] The working principle and beneficial effects of the waste paint recycling process provided by this invention are as follows: During operation, diaphragm pumps rely on the reciprocating motion of the diaphragm to change the volume of the pump chamber. When the diaphragm moves to one side, the volume of the suction chamber increases, creating negative pressure to draw in waste paint, while the volume of the discharge chamber decreases, squeezing the liquid to discharge it. When the diaphragm moves in the opposite direction, the suction and discharge alternate. Driven by pneumatic or electric power, the diaphragm reciprocates, enabling continuous transport of waste paint. As a positive displacement pump, it allows for shaft seal leakage during material transport. It is well-suited to the volatile organic solvents in waste paint, offering excellent environmental performance. It can run dry, has strong self-priming capabilities, and can handle conditions with large fluctuations in the liquid level of the waste paint storage tank. It is also highly adaptable to various media, capable of transporting untreated waste paint containing small amounts of crystalline particles and fine gravel. It can complete the feeding of the settling tank without additional filtration, and its flow rate is easily adjustable to flexibly match different feed rate requirements in the pretreatment stage. It operates stably and is easy to maintain. Example

[0020] In the waste paint recycling process, the waste paint is transported to settling tank 1 by a centrifugal pump. After settling in settling tank 1, the waste paint forms a supernatant and an impurity layer. The impurity layer is discharged through the lower discharge port, and the supernatant is transported to the evaporation and recovery unit by a pump.

[0021] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: During the centrifugal pump's transport process, the centrifugal force generated by the high-speed rotation of the impeller gives the liquid inside the pump kinetic and pressure energy. Under the action of centrifugal force, the liquid is thrown from the center of the impeller to the edge of the impeller, and after being guided by the pump casing, it is discharged along the outlet pipe. At the same time, a negative pressure is formed at the center of the impeller, continuously drawing in waste paint liquid to complete the transport. By increasing the flow rate and improving the transport efficiency through the centrifugal pump, it can adapt to the large flow rate feeding requirements of the waste paint liquid pretreatment stage and the feeding conditions of the settling tank. It has a simple structure, stable operation, and low maintenance cost. It can continuously transport the supernatant of waste paint liquid without large particulate impurities for a long time, meeting the batch transport requirements in the process. Example

[0022] In the waste paint recycling process, the waste paint is pumped to settling tank 1 by a screw pump. After settling in settling tank 1, the waste paint forms a supernatant and an impurity layer. The impurity layer is discharged through the lower discharge port, and the supernatant is pumped to the evaporation and recovery unit.

[0023] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: During the conveying process by the screw pump, a sealed cavity is formed by the meshing of the stator and rotor. When the rotor rotates, the sealed cavity moves from the suction end to the discharge end along the pump body axis, smoothly pushing the waste paint liquid to the settling tank. The medium is conveyed by the volume change of the sealed cavity. It is a positive displacement pump. The screw pump delivers stable pressure and uniform flow without pulse fluctuations, which can avoid the suspension of impurities caused by pressure changes during the conveying of waste paint liquid. It ensures the effect of static settling of waste paint liquid in the settling tank. It has self-priming capability, can cope with the situation of low liquid level in the waste paint liquid storage tank, and can convey waste paint liquid containing a small amount of fine impurities, which is suitable for the characteristics of raw materials in the pretreatment stage. Example

[0024] When the waste paint recycling process is carried out intermittently, the evaporation time of each batch of material in evaporator 2 is 1 hour, and the cooling time of the material after evaporation is 2 hours. Short evaporation and short cooling time are selected. The heating power of evaporator 2 is precisely increased by the proportional regulating valve of the steam pipeline to quickly increase the temperature inside the vessel to the set value, so as to realize the rapid volatilization and separation of organic solvents. In the cooling stage, the material temperature is quickly reduced by natural air cooling combined with the heat exchange structure of the vessel body, and the heat exchange time is shortened.

[0025] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: By controlling the evaporation and cooling time, the processing cycle of a single batch is significantly shortened, making it suitable for production conditions where the amount of waste paint is large and the regeneration process needs to be completed quickly. It can ensure the efficient progress of two standard batch processing sessions per day, improving the overall processing efficiency. In addition, short-time evaporation can reduce the heat loss of the effective components of the paint, and the physical and chemical properties of the material after cooling are more stable, making it easier to enter the subsequent processing stage of the dispersion tank 5. Example

[0026] When the waste paint recycling process is carried out intermittently, the evaporation time of each batch of material in evaporator 2 is 2 hours, and the cooling time of the material after evaporation is 3 hours. By adopting a medium evaporation and cooling time, the temperature of evaporator 2 is controlled to a mild range, so that the organic solvent in the waste paint gradually and fully evaporates, and the organic phase and the residue in the evaporator are accurately separated. In the cooling stage, a gradient cooling method is adopted to slowly reduce the temperature of the material and avoid the agglomeration and stratification of the residue in the evaporator due to sudden temperature changes.

[0027] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: This evaporation-cooling time balances processing efficiency and separation effect. It avoids insufficient recovery of organic solvents due to excessively short evaporation, and also avoids affecting the quality of residues in the reactor due to excessively rapid cooling. It is a universal working condition suitable for conventional waste paint recycling treatment, and can simultaneously ensure the purity of recovered paint thinner and the quality of raw materials for recycled industrial paint. The equipment operates under stable load and has more reasonable energy consumption. Example

[0028] In the waste paint recycling process, when the process is carried out intermittently, the evaporation time of each batch of material in evaporator 2 is 3 hours, and the cooling time of the material after evaporation is 4 hours. By adopting a long evaporation and long cooling time, the waste paint is evaporated at a low heating temperature for a long time, so that trace amounts of non-volatile organic solvents in the waste paint can be fully volatilized and recovered. The cooling stage adopts slow heat exchange cooling throughout the process, so that the molecules of the material remaining in the reactor can be fully stabilized and the internal stress of the material can be reduced.

[0029] Compared with related technologies, the waste paint recycling process provided by this invention has the following advantages: By controlling the evaporation and cooling time, the recovery of organic solvents is maximized, improving resource utilization. This method is suitable for treating waste paint containing high-value-added organic solvents. After the residue is fully cooled, it has a uniform texture and good fluidity. When it is ground in the sand mill 6, the particle size is finer, which can significantly improve the specific surface area and adhesion of recycled industrial paint and optimize the performance of the final product.

[0030] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A waste paint recycling process, characterized in that, Includes the following steps: S1: Waste paint is pumped to a settling tank. After settling in the settling tank, the waste paint forms a supernatant and an impurity layer. The impurity layer is discharged through the lower discharge port, and the supernatant is pumped to the evaporation and recovery unit. S2: Waste paint from the settling tank is pumped to the evaporator. The steam pipeline is turned on to heat the evaporator. The appropriate evaporation temperature and evaporation time are set. The gas volatilized during the evaporation process is condensed into liquid by the condenser and flows by gravity to the receiving tank. At the same time, organic solvent is added and stirred evenly to form paint thinner. Then it is discharged into the ton container through the drain port. S3: After the materials participating in the reaction in the evaporation kettle are cooled, they are transported to the dispersion kettle by a transfer pump. At the same time, solvent is added to the dispersion kettle and mixed and stirred evenly. The dispersed and stirred materials are then transferred to a sand mill for grinding to process the paint particles to a finer level, thereby improving the specific surface area, adhesion and other properties of the paint. The semi-finished paint after sand milling is sent to a regulating and mixing tank, and then filled and packaged by a filling machine.

2. The waste paint recycling process according to claim 1, characterized in that, The waste paint recycling process is controlled by a PLC and operates intermittently.

3. The waste paint recycling process according to claim 1, characterized in that, The filling machine is equipped with a weighing instrument for weighing and measuring the semi-finished paint.

4. The waste paint recycling process according to claim 1, characterized in that, In S2, a vacuum unit is used to better evaporate volatile materials, and the evaporation system is operated under negative pressure.

5. The waste paint recycling process according to claim 1, characterized in that, In step S3, pigment powder is added to appropriately change the color of the recycled paint.

6. The waste paint recycling process according to claim 1, characterized in that, The pump used in S1 can be a diaphragm pump, a centrifugal pump, or a screw pump.

7. The waste paint recycling process according to claim 2, characterized in that, During the intermittent operation, the evaporation time of each batch of material in the evaporator is 1-3 hours, and the cooling time of the material after evaporation is 2-4 hours.

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