Method for treating and recycling metalworking emulsion waste liquid and soap residue

Abstract

A method for processing and recycling of metal processing emulsified waste liquid and soap residue The present application provides a method for near-zero discharge and resource recycling of metal rolling and steel pipe expanding waste oil liquid, which is aimed at a large amount of insoluble metal soap residue (HW08) and its emulsified waste liquid (HW09) generated in non-ferrous metal hot rolling cooling lubrication and steel pipe expanding oil flushing, etc. The soap residue is emulsified and then dissolved in the emulsified waste liquid, mechanical impurities are filtered out, and then MVR distillation separation is carried out. The distilled water can be directly reused as a diluent for emulsified liquids for rolling, cutting, etc. or flushing water for expanding oil, or the water is reused after biochemical or membrane purification treatment. The MVR concentrated liquid can be used as a basic raw material for metal processing liquid, and is adjusted to form metal cutting fluid or rolling liquid products, etc., so that the green cycle of mechanical manufacturing lubricant is realized.

Description

Technical Field

[0001] This invention relates to the treatment and resource-based green recycling of emulsified hazardous waste oil in metal cutting, hot rolling, and steel pipe expansion processes. Background Technology

[0002] Emulsified waste oil discharged in large quantities during wet processing such as metal cutting, hot rolling, and steel pipe expansion is classified as "HW08-09" hazardous waste, and is associated with manufacturing... With the rapid development of the industry, the discharge of emulsified waste oil involved in such metal processing has also increased. Due to the high COD value, complex organic components, and emulsification characteristics of this type of waste oil, it is difficult and costly to treat. Improper treatment and disposal can cause serious pollution hazards to the environment. In particular, the high viscosity insoluble metal soap residue generated by the cooling and lubrication of hot rolling of non-ferrous metals and the lubrication and rinsing of steel pipe expansion is a common problem. Currently, the traditional disposal method of production enterprises is to directly outsource the soap residue (HW08) to institutions with solid waste treatment qualifications for legal incineration. However, there is also the risk of pollution caused by improper disposal driven by the profit chain. Emulsified waste liquid is generally treated by traditional methods such as demulsification → flotation → biochemical treatment or membrane purification, and then reused as reclaimed water or connected to the local dedicated sewage pipeline for collection and treatment after meeting the industrial wastewater discharge standards. A new type of high-efficiency and energy-saving vapor recompression (MVR) technology is being increasingly used for energy-saving and emission-reduction treatment of high-concentration emulsified wastewater. The COD of distilled water treated by MVR can be reduced by more than 95%, and the B and C values ​​are usually greater than 0.35. It is very suitable for subsequent biological or membrane treatment to meet standards before discharge or for reuse as wastewater. The energy-saving and emission-reduction effects are obvious. However, the concentrated liquid discharged has a high oil content, complex organic components, and is classified as hazardous waste. At present, the technology for treatment is difficult, the policy restrictions are high, and the resource utilization rate is extremely low. Summary of the Invention

[0003] Based on the formulation composition of products such as non-ferrous metal rolling fluid and steel pipe expansion oil, as well as the generation of processing waste liquid and the causes of metal soap residue, this invention is guided by the system engineering design concept of resource-based green recycling and traceability-based regeneration. It starts from the optimization of product use and maintenance and emission source management to ensure that the waste liquid is not mixed or putrefied, thus providing the necessary technical guarantee for resource-based regeneration.

[0004] Rolling fluids, expanding oils, and other similar products are typically formulated from naphthenic oils, lubricating esters, oleic acid, preservatives, emulsifiers, and other compounds.

[0005] Non-ferrous metal hot rolling fluid is prepared as an emulsion with a concentration of 2%-10%. During the rolling process, due to the strong extrusion and friction between the rolls and the rolled metal material, a large amount of insoluble metal soap residue will be generated in the emulsion medium during the lubrication and cooling process. The soap residue needs to be continuously skimmed off and the original liquid added to maintain the concentration of the processing fluid.

[0006] Steel pipe expansion is achieved by using a mechanical expansion head to forcefully expand the inner wall of the steel pipe to meet technical requirements such as prestress, inner wall roughness, and large pipe diameter geometry. The lubricating and friction-reducing expansion oil added during the expansion process will generate a large amount of metal soap residue and emulsified waste liquid during subsequent rinsing.

[0007] This invention uses emulsification and resolution technology to formulate a composite emulsifying additive-A for the above-mentioned high-viscosity hazardous waste soap residue. The additive-A is then mixed with the soap residue at a weight ratio of 1:0.5-1.5 to form an emulsified oil, which is then resolution of the filter residue. The resolution diluent can be water or emulsified waste liquid. The formulation components of composite emulsifier-A are as follows: Polyol amines: 55%-100%, polyesters: 0%-37%, oleic acid: 0%-38%, fatty alcohol polyoxyethylene ethers: 0%-35%.

[0008] The emulsified waste liquid after the redissolution of soap residue emulsification is usually filtered to remove particulate impurities by means of sedimentation, centrifugation, membrane media separation, and stripping, and then evaporated by MVR to obtain a concentrated liquid with water content <20% and mechanical particulate impurities <0.5%. This concentrated liquid is used as a special base oil for the production of metalworking fluids. Based on the evaluation of its components and functions such as emulsification, lubrication, rust prevention, defoaming, and antibacterial properties, and compounding experiments, in accordance with the technical requirements of recycled metalworking fluid products, a special functional regeneration composite additive-B is formulated. It is then mixed and formulated into metalworking fluid products such as cutting fluids or rolling fluids at a weight ratio of base oil to composite additive-B of 1:0.5-1.5. The formulation components of the composite additive-B are as follows: Polyol amines: 10%-28%, polyesters: 25%-37%, oleic acid: 15%-25%, fatty alcohol polyoxyethylene ethers: 10%-25%.

[0009] See the attached diagram in the instruction manual.

[0010] Figure 1 in the accompanying drawings is a process flow diagram of the present invention. Detailed Implementation

[0011] Implementation Case 1 An aluminum hot-rolling production enterprise discharges more than 35 tons / day of emulsified wastewater, which is collected in a dedicated buffer and equalization tank. The wastewater contains 10% aluminum soap scum, has a pH of 6.8, a concentration of 5.0%, and 0.8% mechanical impurities. Emulsifier-A prepared according to this invention is mixed with 10% soap scum at a 1:1 weight ratio and dissolved in 90% of the emulsified wastewater. Mechanical particles are removed by a fiber cloth filter press, followed by MVR evaporation and separation. The filter residue (HW08) is outsourced for disposal. The resulting distilled water has a pH of 6.9 and is directly reused as a diluent for the rolling concentrate. The resulting concentrate contains 18.5% water and 0.41% mechanical impurities. This concentrate is used as a base oil and mixed with emulsifier-B at a 1:1 ratio to produce a cutting fluid product. The yield is 35% of the emulsified wastewater volume, including 20% ​​composite additives.

[0012] Implementation Case 2 A steel pipe plant generates over 10 tons / day of expansion oil flushing emulsion wastewater in its pipe expansion section, which is discharged into a wastewater collection tank. The wastewater contains approximately 15% metallic soap residue, has a pH of 7.1, a concentration of 6.5%, and mechanical impurities of <1.1%. The composite emulsifier-A of this invention is mixed with 15% soap residue at a weight ratio of 1:0.85 and then added to the emulsion wastewater. Mechanical impurities are removed using a plate and frame filter press. The sludge (HW-08) is legally disposed of by an external contractor. The filtrate is concentrated and separated using an MVR (Medium-Volume Resin) system. The resulting distilled water is directly reused as flushing water for the expansion oil. The resulting concentrate contains 15.7% water and 0.5% mechanical impurities. This concentrate is used as a base oil and mixed with composite emulsifier-B at a weight ratio of 1:0.7 to produce the steel pipe rolling fluid product.

Claims

1. A method for treating and regenerating metal processing emulsion waste liquid and soap residue, characterized in that, Includes the following steps: (1) Prepare compound emulsifying additive-A by mixing the soap residue and the additive-A at a weight ratio of 1:0.5 to 1.5, emulsifying them, and then adding them to the emulsified waste liquid or water for redissolution; (2) Filter out mechanical impurities in the reconstituted solution; (3) The purified liquid is subjected to MVR distillation to obtain a concentrated liquid with a water content of <20% and mechanical impurities of <0.5%; (4) The concentrate is used as a base oil and mixed with composite emulsifying additive-B at a weight ratio of 1:0.5 to 1.5 to prepare cutting fluid or rolling fluid products; The soap residue is an insoluble metal soap residue. This insoluble metal soap residue is produced during the hot rolling of non-ferrous metals by a rolling emulsion prepared at a concentration of 2% to 10%, which, under the strong extrusion and friction between the rolls and the rolled metal material, is generated during lubrication and cooling and continuously precipitates to the surface. Alternatively, the insoluble metal soap residue is produced during the expansion of steel pipes by a lubricating and friction-reducing expansion oil added during the subsequent rinsing after the mechanical expansion head forcefully expands the inner wall of the steel pipe. The formulation composition of the composite emulsifying additive-A is as follows (by weight percentage): Polyol amines: 55%–100%, Polyesters: 0%–37%, Oleic acid: 0%–38%, Fatty alcohol polyoxyethylene ether: 0%~35%; The formulation composition of the composite emulsifying additive-B is as follows (by weight percentage): Polyol amines: 10%–28%, Polyesters: 25%–37%, Oleic acid: 15%–25%, Fatty alcohol polyoxyethylene ether: 10%~25%.

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