JPH024898A - Re-treatment of waste lubricating oil - Google Patents

Abstract

PURPOSE:To raise removal ratio of admixtures, to prevent filtration troubles and to improve recovery ratio of regenerated oil by reacting waste lubricating oil with an aqueous solution of caustic alkali under heating, uniformly dispersing diatomaceous earth, etc., into the reaction mixture and removing admixtures. CONSTITUTION:Waste lubricating oil used for cold working is heated with an aqueous solution of caustic alkali at 100 deg.C and fine particles of coating film of phosphate in admixtures is precipitated and removed. Then diatomaceous earth and activated clay are uniformly dispersed into the waste lubricating oil, separated and removed together with the admixtures remaining in the waste oil by a centrifugal separator and further the waste oil is incorporated with a filter aid and filtered to remove the admixtures.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for recycling waste lubricating oil, such as die lubricating oil used in cold forging.

Cold forging using conventional technology molds is highly productive because parts with the shape of the mold can be manufactured directly from the raw material, and it is also excellent in terms of resource conservation as there is less wasted material.
This is a processing method that is widely used in automobile manufacturing and other industries.

Since cold forging is performed at room temperature, there is a greater frictional force between the mold and the material than in hot steel forging, and simply applying mold lubricating oil to the mold may result in insufficient oil film formation and insufficient heat resistance. Burning is likely to occur. Therefore, in cold forging processing, the material to be processed is subjected to a phosphate coating treatment in advance to form a coating with excellent lubricity and wear resistance on the surface of the material before processing.

For this reason, the mold lubricating oil that is used while being circulated between the oil tank and the cold water tank is unavoidably contaminated with phosphate sludge (commonly known as Bonde sludge), sludge (sediment), As the amount of scum (floating matter) increases, machine troubles are more likely to occur. Therefore, after the mold lubricating oil has been used for a predetermined period of time, it is replaced with new oil, and although the cycle varies depending on the state of use, it is generally 2 to 4 months.

The used mold lubricating oil that has been replaced, that is, the waste oil that contains a lot of contaminants, is mixed with other waste liquids (for example, JP-A-61-12
In many cases, such waste oil from cold forging mold lubricating oil was incinerated without being recycled, as no suitable disposal method could be found as seen in Publication No. 3639).

As described above, the reason why waste oil used for cold forging lubricating oil is not often recycled is that the waste oil contains a large amount of impurities (more than 3%), and the viscosity has increased from the initial high viscosity of 75 cst to 1.
This is because it is difficult to separate and eliminate impurities as the oil temperature is higher than 00 cst. Conventional conventional waste oil recycling methods, such as heating the waste oil to lower its viscosity, are difficult.
When contaminants are treated by static separation or centrifugal separation, the contaminant removal rate is limited to 30 to 60%, and moreover, the contaminant removal rate is 20% higher than the heating temperature (80°C) used in boat fishing.
It had to be heated to around 0'C.

Additionally, attempts have been made to recycle waste oil by adding diatomaceous earth or activated clay as a filter aid or adsorbent. For example, Fig. 2 shows a process flow sheet of a conventional lubricating waste oil regeneration treatment plant using diatomaceous earth. After being heated to a temperature above .degree. C. to lower the viscosity, it is passed through a centrifuge 3. The impurities separated by the centrifugation n3 are collected as separation shafts in the separation shaft tank 4, and the separated oil from which the separation shafts have been removed is collected in the separation oil tank 5. The recovered separated oil is sent to a heating dehydration tank 6 and heated to 100 to 120°C, and the moisture is discharged as steam. The treated oil from which water has been removed is sent to the diatomaceous earth mixing tank 7, where diatomaceous earth is added in an amount (for example, 3.0 to 7.0%) according to the amount of impurities contained in the treated oil, and is uniformly dispersed. Stir and mix as shown. Then, the diatomaceous earth mixed oil is sent to the filter breath 8 and filtered, the filtered residue is collected in the filtered residue pallet 9, and the filtered treated oil is collected as recycled oil in the recycled oil tank 10, and the filtered oil is collected in the recycled oil tank 10 as recycled oil. It is packed in a container 11 such as a type yJ lubricant and reused.

Problems to be Solved by the Invention However, in the conventional regeneration treatment method described above, for example, if the amount of diatomaceous earth added is insufficient, the filtration of the filter press will quickly become clogged, which tends to cause treatment troubles such as inability to process. Ta. The cause of this filter clogging is the diameter 1
It is presumed that the fine particles of Bonde lees of about 30 microns block the pores of the diatomaceous earth, and as a countermeasure, it was necessary to perform regeneration treatment by frequently washing the filter cloth.

In addition, when recycled oil is recycled using the conventional method described above, the recycled oil contains impurities! (83 value) is in the range of 0.2 to 1.0%, and fine particles of bondage residue with a diameter of 1 μm or less remain. Therefore, if this recycled oil is reused as a lubricating oil, the lifespan of the recycled oil will be extremely shortened, so the recycled lubricating oil should be mixed with about 50% new mold lubricating oil. There were problems such as having to do so.

This invention was made against the above-mentioned technical background.
1! Improves the removal rate of impurities, prevents filtration troubles, and has a high recovery rate of recycled oil! The purpose is to provide a method for recycling waste oil.

Means for Solving the Problems As a means for solving the above problems, the method for regenerating lubricating waste oil of the present invention includes adding a caustic alkaline aqueous solution to lubricating waste oil and heating it to 100°C or higher to precipitate impurities. a heating reaction treatment step for removing diatomaceous earth and activated clay; a centrifugation treatment step for adding and uniformly dispersing diatomaceous earth and activated clay, and separating and removing the impurities remaining in the lubricating waste oil using a centrifugal separator;
Add a filter aid such as diatomaceous earth, filter and a! It is characterized by performing a filtration treatment step to remove impurities from the waste oil.

Effect According to the above method, first, a heating reaction treatment step is performed, and 8! When an aqueous caustic alkali solution is added to the waste oil and heated to 100° C. or higher, the fine particles of the phosphorus-11 salt-coated residue, such as zinc phosphate, contained in the impurities undergo a chemical change and become coarse particles.

For example, sparingly soluble zinc phosphate becomes a compound such as zinc hydroxide or zinc soap and precipitates, and water is also removed at the same time.

[Main chemical reaction formula] 2rr3 (PO4)2 +6NaOH+2RCOOH
(fl-soluble zinc phosphate) (caustic soda) 2rb (P
O4)2+4H20+2RCOOHAlso, in the centrifugation process, a mixture of diatomaceous earth and activated clay is added as a separation aid, and the fine particles in the impurities are adsorbed into the pores of the diatomaceous earth and activated clay, and then centrifugation is performed. Impurities are efficiently separated and removed together with diatomaceous earth and activated clay.

In the filtration step, when a filter aid such as diatom is added and filtered using a filter press or the like, impurities in the lubricating oil are removed together with the filter aid.

Therefore, the fine particles of the phosphate coating in the contaminants are coarsened and precipitated in the heating reaction treatment process and removed, and in the centrifugation treatment process they are adsorbed to diatomaceous earth and separated and removed. In the filtration step, the diatoms and the like are efficiently filtered without clogging the filter.

EXAMPLE Hereinafter, an example of the method for regenerating lubricating waste oil of the present invention will be described with reference to the regeneration process flow sheet shown in FIG.

The waste oil from mold lubricating oil used in cold forging processing contains a large amount of impurities such as bonding scum, and these impurities are dispersed in the waste oil without settling because the viscosity of the waste oil is high at room temperature. are doing. The composition of impurities includes moisture, iron oxide, iron hydroxide, nitrous phosphate (bonde lees), silica (dust), etc.
This waste oil is first sent to a heating reaction tank 12 from a container 11 such as a drum, and an aqueous caustic alkali solution such as caustic soda or caustic potash having a concentration of about 0.1% is added thereto. The amount of this caustic alkaline aqueous solution added is between 2 and 3 times the amount of waste oil.
It is about 5%, and after addition, it is heated to 100° C. or higher by a steam heater installed in the heating reaction tank 12. In waste oil to which an aqueous caustic alkali solution is added and heated to h0, fine particles of zinc phosphate in particular chemically change into zinc hydroxide and zinc soap, become coarse particles, and precipitate to form a slurry. The heating reaction time is about 30 to 60 minutes.

Then, the slurry of impurities precipitated in the heating reaction tank 12 is discharged from the drain at the bottom and becomes the slurry tank 1.
It will be collected on 3rd.

On the other hand, the treated oil remaining in the heating reaction tank 12 is sent to the heating tank 14, where about 2.5% of activated clay and diatomaceous earth are added and mixed by stirring. The mixed Sagiho oil is then heated to over 100°C with a steam heater to drive out the moisture contained in the pores of the activated clay and diatomaceous earth, and instead remove the fine particles of impurities in the treated oil. Adsorb into the hole. The time required for this adsorption is about 30-60 minutes. Next, the activated clay and diatomaceous earth that have been subjected to centrifugal separation 15 and have adsorbed impurities are collected as separated lees in a separated lees tank 16, and the separated oil is collected in a separated oil tank 17.

The separated oil collected in the separated oil tank 17 is sent to a heated dehydration tank 18 and heated to 110°C using a steam heater.
By heating to a higher temperature, water is removed as water vapor.

Further, the water-removed oil is sent to the diatomaceous earth mixing tank 19, and about 1 to 3% of the oil amount of diatomaceous earth is added thereto, heated to 100° C. or higher, and stirred and mixed. After stirring and mixing for about 30 minutes, it is sent to a filter press 20 and filtered, and the filtration residue is collected in a filter residue pallet 21, and most of the impurities with a diameter of 1 μ or more are removed and collected in a recycled oil tank 22. After quality inspection, the recycled oil is packed into a container 23 such as a drum and used as mold lubricating oil.

Next, we will discuss Example 1 in which regeneration treatment was actually performed using the regeneration treatment method for lubricating waste oil of this example, and regeneration treatment in which the heating reaction treatment step in Example 1 was omitted in order to see the effect of the heating reaction treatment step. Reference Example 1 in which the regeneration process was performed and a comparative example in which the regeneration process was performed using the conventional method will be described.

[Comparative Example 1] The sample oil was a waste oil of a cold forging lubricant (Kyodo Yushi Co., Ltd., manufactured by Taisei, Sarkurat Y-50A), and its properties are as shown in Table 1.

Unit 2a: ppm Table 1, No. 38 Unit: ppm 5S value = 0.8μ The amount of suspended solids that cannot pass through a Millipore filter in waste oil, expressed as a percentage.

The above sample oil was processed using the conventional reprocessing method shown in the process flow sheet in Figure 2, and the properties of the centrifuged oil and recycled oil were compared with the properties of the new oil in a second test. Shown in the table. In addition, diatomaceous earth has a ratio of about 6% to the amount of oil processed.
Added 0%.

Then, the metal elements in the oil of the sample oil, centrifuged oil, and recycled oil were analyzed using an ICP analyzer (ICP is Tnduct).
Table 3 shows the results of the analysis using ively Coupled Plasla.

As a result, for example, the amount of zinc contained in the sample oil decreased from 8,655 ppn to 7,487 ppn in Comparative Example 1, and was removed by about 13%.

[Example 11 Waste oil equivalent to the test oil used in the comparative example was recycled according to the process flow sheet of the method of the present invention shown in FIG. However, the amount added to the treated oil is 3.0% caustic soda, 2.5% mixture of diatomaceous earth and activated clay as a separation aid, and 1.0% diatomaceous earth as a filter aid.
It is.

Table 4 shows the properties of the sample oil, the centrifuged oil, and the recycled oil. Furthermore, Table 5 shows the analysis results of metal elements in the oil at each treatment stage.

Table 4 Unit: p- Table 5 As a result, for example, the amount of zinc contained in the sample oil decreased from 7217 ppIm to 4487 ppI in Example 1, and was removed by about 38%.

The separation aid added to the IIJ waste oil in the centrifugation process is a 1:1 mixture of diatomaceous earth and activated clay. Hanging (S
S value) is determined as appropriate.

rReference Example 1 Waste oil equivalent to Example 1 was regenerated by the method shown in the process flow sheet of FIG. 1 by omitting the heating reaction treatment step. The amount added to the treated oil was 3.0% of a mixture of diatomaceous earth and activated clay as a separation aid, and 2.5% of diatom as a filter aid.

Table 6 shows the properties of the sample oil, the properties of the centrifuged oil, and the properties of the recycled oil. Table 7 also shows the analysis results of metal elements in the oil.

Table 6 Unit: pDI Table 7 As a result, for example, the concentration of zinc contained in the sample oil decreased from 6755 ppn to 5160 ppi in Reference Example 1, which was about 23% removed.

Furthermore, when Comparative Example 1, Example 1, and Reference Example 1 are compared in terms of SS values of the recycled oil obtained by each treatment method, the recycled unit treated in Comparative Example 1 using the conventional method: ppm oil is 0. .6% and 0.0 for recycled oil treated in Example 1.
4%, and 0 in Reference Example 1 where no heating reaction treatment step was performed.
．． It was 41%.

Detailed Description of the Invention According to the method of the present invention, in the heating reaction treatment step, a caustic arunonol aqueous solution is added to the lubricating waste oil and heated to 100°C or higher to chemically change and precipitate impurities. At the same time, in the centrifugation process, diatomaceous earth and activated clay are added as separation aids, and the impurities are separated and removed by a centrifuge, and further, in the filtration process, a filter aid such as diatomaceous earth is added. Since the impurities in the lubricating waste oil are removed by filtration, the fine particles of the impurities are coarsened in the heating reaction treatment process.
In addition to being precipitated and removed, the separation of impurities during the centrifugation process is improved, resulting in filtration! I! ! Eliminates troubles caused by clogging of filters in the LL process,
The removal rate of impurities was improved from 40% in the conventional method to 70%.

In addition, in the case of conventional methods, the SS value of recycled oil, which was about 0.1 to 1.0%, can be clarified to 0.1% or less, and only 100% recycled oil can be used as expanded lubricating oil. This makes it possible to reduce the amount of new oil used.

In addition, the occurrence of troubles such as filter clogging is reduced, and the amount of separated sludge that is generated is also reduced.
This has the effect of increasing the recovery rate of recycled oil from 1.5% to 65% or more.

[Brief explanation of the drawing]

Fig. 1 is a process flow sheet of a regeneration treatment facility showing an example of this defense method, and Fig. 2 is a process flow sheet of a conventional regeneration 12! l
This is a process flow sheet for the 100-meter facility. 12... Heating reaction tank, 14... Heating tank,
15... Centrifugal separation art, 17... Separation oil tank,
128... Heating dehydration tank, 19... Diatomaceous earth mixing tank, 20... Filter press, 22...
Recycled oil tank, 23... Container such as a drum can.

Claims (1)

[Claims] A heating reaction treatment step in which a caustic alkaline aqueous solution is added to lubricating waste oil and heated to 100°C or higher to precipitate and remove impurities, and diatomaceous earth and activated clay are added and dispersed uniformly.
A centrifugal separation process in which impurities remaining in the lubricating waste oil are separated and removed using a centrifuge, and a filtration process in which a filter aid such as diatomaceous earth is added and filtered to remove impurities in the lubricating waste oil are performed. A method for recycling waste lubricating oil, characterized by: