Treatment Method for Recycling Oil from Neodymium-Iron-Boron Waste Oil Sludge

Abstract

The present invention relates to a method for treating and recovering oil from neodymium iron boron waste oil sludge. The steps are as follows: Add neodymium iron boron waste oil sludge and water into a reaction kettle, start stirring to mix evenly; Pass steam into the jacket to heat to 40 °C, add sodium hexametaphosphate to change the surface tension between phases. After ultrasonic washing for 10 minutes, disperse the oil in the neodymium iron boron waste oil sludge into water. After standing and separating layers, the ash substances and neodymium iron boron waste precipitate at the bottom, and the oil-water mixture floats on the upper layer. The materials precipitated at the bottom are filtered by a centrifuge, and the filtrate and the upper-layer oil-water mixture are to enter the next process; After evacuating the air in the rectification column, flow the mixed liquid from the reaction kettle into the rectification column at a rate of 0.5 L / min, start the heater, control the temperature between 75 °C and 85 °C, and carry out interphase heat and mass transfer. After water and additives reflux for 15 minutes first, turn off the reflux. Observe from the bottom sight glass of the rectification column that the ratio of agent to oil by volume is 1:5, and obtain cutting oil from the residue outlet of the rectification column.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste oil recovery, and in particular, to a method for treating oil recovered from neodymium iron boron waste oil sludge Background Art

[0002] Neodymium iron boron waste oil sludge is generated during machining processes that use cutting fluids and emulsified oils, resulting in waste oil sludge such as oil-containing water and emulsified waste liquid. The oil content accounts for about 5% of the neodymium iron boron waste oil sludge. The waste oil sludge is difficult to naturally degrade, and stacking it easily pollutes the soil and groundwater. At the same time, when the neodymium iron boron waste oil sludge is exposed to air, it undergoes an oxidation reaction with oxygen in the air, generating heat during the oxidation process and causing spontaneous combustion.

[0003] Currently, the treatment technologies for neodymium iron boron oil-containing waste materials are incineration and pyrolysis. The incineration method involves placing the material in a rotary kiln and heating it to burn through the combustibility of the oil in the neodymium iron boron oil-containing waste. However, this method can cause secondary pollution to the environment during the combustion process of the neodymium iron boron waste oil sludge. The pyrolysis method involves indirectly heating the neodymium iron boron waste oil sludge under a sub-vacuum and airtight condition, utilizing the ignition point of the oil in the waste material to cause pyrolysis of the neodymium iron boron waste oil sludge. This method does not cause secondary pollution to the environment. However, the sub-vacuum pyrolysis method does not recover the oil fraction for reuse in neodymium iron boron machining. During the pyrolysis process of the neodymium iron boron waste oil sludge in a sub-vacuum rotary kiln, it is prone to sintering into balls or adhering to the inner wall of the kiln, resulting in a high operating failure rate of the rotary kiln.

[0004] After retrieval, a patent document related to the content of this application was found. The Chinese patent with the publication number CN108300505A provides a waste oil treatment process, specifically a process that combines traditional distillation and molecular distillation, belonging to the technical field of hazardous waste treatment. It obtains light refined distillation recovered oil and heavy refined distillation recovered oil through processes such as filtration, heating, condensation for oil separation, heating, condensation, and molecular distillation, achieving the treatment and recovery of waste oil. The present invention has developed a method that combines traditional physical treatment and molecular distillation treatment for the recovery of waste oil mainly composed of mineral oil. The precision of the light refined distillation recovered oil and heavy refined distillation recovered oil obtained through recovery is greatly improved compared to traditional processes, and they can be reused according to their different components. The entire waste oil recovery process is environmentally friendly and low in pollution, suitable for industrial production.

[0005] The Chinese patent with the publication number CN107162301A provides a cutting fluid recycling and treatment system, including a four-stage treatment system. The four-stage treatment system includes a first-stage treatment system, a second-stage treatment system, a third-stage treatment system, and a fourth-stage treatment system that are connected in sequence by a pump. The method for recycling and treating cutting fluid includes the following steps: removing chips and oil; MVR demulsification and heat recovery; electrocoagulation oxidation and oil-water separation of concentrated water; microtube filtration, reverse osmosis filtration, and UV oxidation, so that the cutting waste liquid is reduced from a high concentration of COD (average concentration of 150,000 PPM) to below 100 PPM.

[0006] The Chinese patent with the publication number CN101245283A provides a method for recycling and utilizing waste oil, especially a processing method for recycling and utilizing waste oil of industrial oil. It removes impurities by adding a certain amount of impurity remover to the waste oil. The main components of the impurity remover are sulfuric acid, petroleum ether, anhydrous sodium carbonate, and anhydrous ethanol, etc. The impurity remover reacts with various impurities in the waste oil to remove the impurities, and the available oil is obtained. The various types of oil obtained by the processing method of the present invention fully meet the national regulations. The equipment implemented is simple and the operation is simple. Therefore, it is a very ideal processing method for recycling and utilizing waste oil. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a processing method for recovering oil from neodymium iron boron waste oil sludge that is easy to operate, safe, and environmentally friendly.

[0008] The technical solution adopted by the present invention is:

[0009] A processing method for recovering oil from neodymium iron boron waste oil sludge, the steps of which are:

[0010] (1) Add neodymium iron boron waste oil sludge and water into a reaction kettle with a jacket and a stirrer and capable of installing a vacuum distillation column, start stirring, and mix evenly;

[0011] (2) Pass steam into the jacket to heat to 40°C, add sodium hexametaphosphate to change the surface tension between phases. After ultrasonic washing for 10 minutes, disperse the oil in the neodymium iron boron waste oil sludge into the water. After standing and separating layers, the ash substances and neodymium iron boron waste materials precipitate at the bottom, and the oil-water mixture floats on the upper layer. The materials precipitated at the bottom are filtered by a centrifuge, and the filtrate and the upper oil-water mixture are waiting to enter the next process;

[0012] (3) After evacuating the air in the rectification column, the mixed liquid is fed into the rectification column from the reaction kettle at a rate of 0.5 L / min. The heater is turned on, and the temperature is controlled between 75 - 85 °C for interphase heat and mass transfer. When the temperature in the rectification column reaches 75 °C, water and the auxiliary agent are refluxed for 15 minutes first, then the reflux is turned off. By observing through the bottom sight glass of the rectification column, when the volume ratio of water to oil is 1:5 and at a temperature of 80 °C, high-quality cutting oil is obtained from the residue outlet of the rectification column.

[0013] Moreover, in the step (1), the weight ratio of water to the NdFeB waste oil sludge is 1:3.

[0014] Moreover, in the step (1), the stirring speed is 50 r / min.

[0015] Moreover, in the step (2), the weight ratio of water to the NdFeB waste oil sludge is 2000:1.

[0016] Moreover, in the step (3), the rectification column is evacuated to maintain an internal pressure of 0.5 - 0.7 atm.

[0017] Moreover, in the step (3), after the initially refluxed water and sodium hexametaphosphate are heat-exchanged and condensed, they return to step (1) for recycling. The flow rate of the condensed water and sodium hexametaphosphate entering the rectification column is controlled at 1.5 L / min.

[0018] The advantages and positive effects of the present invention are as follows:

[0019] The present invention recovers the waste oil from the NdFeB waste oil sludge and then uses it in the NdFeB machining process, turning waste into treasure, overcoming the technical problem of extracting oil from the NdFeB waste oil sludge, and filling the gap in the technology of recycling oil from the NdFeB waste oil sludge.

[0020] The water and auxiliary agent used in the present invention can be recycled, and the yield of the regenerated oil can reach more than 80%. In theory, zero emissions can be achieved, which is green and environmentally friendly and has good promotion value. Specific Embodiments

[0021] The present invention will be further described in detail below through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0022] A method for treating and recovering oil from NdFeB waste oil sludge, the steps of which are as follows:

[0023] (1) Add 60 Kg of NdFeB waste oil sludge and 20 Kg of water into a reaction kettle equipped with a jacket and a stirrer and capable of installing a vacuum rectification column. Turn on the stirrer (rotation speed: 50 r / min) to mix evenly.

[0024] (2) Pass steam into the jacket to heat it to 40°C, and add 10 g of sodium hexametaphosphate. Sodium hexametaphosphate can change the surface tension between phases. After ultrasonic washing for 10 min, the oil in the neodymium iron boron sludge waste is dispersed into water. The separation and layering utilize the selective dissolution ability of the organic polar solution of the auxiliary agent to dissolve the detergent dispersant adsorbed by the solid particles dispersed in the waste oil, causing the solid particles to flocculate. The solubility of the auxiliary agent in substances with high relative molecular mass is small, causing substances with high relative molecular mass, ash substances, and solid particles to precipitate together. On the one hand, the auxiliary agent extracts the base oil from the waste oil, and on the other hand, it flocculates impurities. According to the mass density of substances, after standing and layering, the ash substances and neodymium iron boron waste precipitate at the bottom, and the oil-water mixture floats on the upper layer. After the materials precipitated at the bottom are filtered by a centrifuge, the filtrate and the upper oil-water mixture are waiting to enter the next process;

[0025] (3) After evacuating the air in the rectification column, control the pressure in the column at 0.5 - 0.7 atm. After the pressure in the column reaches the required value, flow the mixed liquid from the reaction kettle into the rectification column at a rate of 0.5 L / min. Turn on the heater and control the temperature between 75 - 85°C for interphase heat and mass transfer. When the temperature in the rectification column reaches 75°C, the easily volatile components, water and the auxiliary agent, first reflux for 15 min, then turn off the reflux. After water and sodium hexametaphosphate enter heat exchange and condensation, they can return to step (1) for regeneration and recycling. The flow rate of the condensed water and sodium hexametaphosphate entering the rectification column is controlled at 1.5 L / min. Observe the water:oil volume ratio as 1:5 from the bottom sight glass of the rectification column. At a temperature of 80°C, 49.3 Kg of neodymium iron boron magnet cutting oil is obtained from the residue outlet of the rectification column, and the yield of the regenerated oil is weighed to reach 82.1%.

[0026] The obtained neodymium iron boron magnet cutting oil is tested, and the relevant indicators (see the following table) meet the standards and can be used in the machining process.

[0027]

[0028] Although the embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art can understand that: without departing from the spirit and scope of the present invention and the appended claims, various substitutions, changes, and modifications are possible. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.

Claims

1. A treatment method for recovering oil from NdFeB waste oil sludge, characterized in that: its steps are as follows: (1) Add NdFeB waste oil sludge and water into a reaction kettle with a jacket and a stirrer, start stirring, and mix evenly; in step (1), the weight ratio of water to NdFeB waste oil sludge is 1:3; (2) Pass steam into the jacket to heat to 40 °C, add sodium hexametaphosphate to change the surface tension between phases, after ultrasonic washing for 10 min, disperse the oil in the NdFeB waste oil sludge into water, after standing and separating layers, the ash substances and NdFeB waste materials precipitate at the bottom, the oil-water mixture floats on the upper layer, the materials precipitated at the bottom are filtered by a centrifuge, and the filtrate and the upper oil-water mixture are to enter the next process; in step (2), the weight ratio of water to NdFeB waste oil sludge is 2000:1; (3) After evacuating the air in the rectification column, flow the mixed liquid from the reaction kettle into the rectification column at a rate of 0.5 L / min, start the heater, control the temperature between 75 °C and 85 °C, carry out interphase heat and mass transfer, when the temperature in the rectification column reaches 75 °C, water and sodium hexametaphosphate first reflux for 15 min, then stop the reflux, observe from the bottom sight glass of the rectification column that the volume ratio of water to oil is 1:5, and at a temperature of 80 °C, obtain cutting oil from the residue outlet of the rectification column.

2. The treatment method for recovering oil from NdFeB waste oil sludge according to claim 1, characterized in that: in step (1), the stirring speed is 50 r / min.

3. The treatment method for recovering oil from NdFeB waste oil sludge according to claim 1, characterized in that: in step (3), the rectification column is evacuated to maintain an internal pressure of 0.5 - 0.7 atm.

Images