WO1991000329A1

WO1991000329A1 - Process for the treatment of used oil

Info

Publication number: WO1991000329A1
Application number: PCT/EP1990/000978
Authority: WO
Inventors: Fritz Basler
Original assignee: Geut Ag Gesellschaft Für Energie- Und Umwelttechnik; Geut Energie- Und Umwelttechnik Aktiengesellschaft
Priority date: 1989-06-26
Filing date: 1990-06-20
Publication date: 1991-01-10
Also published as: AU5857190A; DE3920869A1

Abstract

Process for the treatment of and especially the removal of metals and soot from, used oil which may be performed in three successive stages. In stage (a) the used oil is treated at temperatures of up to 150°C with an active quantity of an aqueous solution of a mixture of at least two strong acids and/or at least two salts of a weak base and a strong acid or precursors thereof. In stage (b) the product obtained is freed of water and cured at high temperatures and in stage (c) the oil in the product thus obtained is separated from the solids.

Description

Process for the treatment of waste oil

Description

The present invention relates to a method for processing, in particular for demetallizing and deblocking, waste oil, in particular used engine oils and bilge oils from diesel engines.

The processing of waste oils for use, so-called recycling, is both economically and ecologically necessary. The use of processed waste oils (regenerated oils) as fuels and fuels is bound to legal regulations with regard to their content of foreign substances, because the latter are released in combustion in unchanged or modified form and can therefore contaminate the air in an inadmissible manner with pollutants. Similar requirements are placed on regenerate oils if they are used as base oils for the renewed production of lubricating oils.

The foreign substances, the concentration of which in the recovered waste oils is subject to legal restrictions or must be restricted for technical reasons when using the regenerated oils as base oils, include inorganic and organic compounds of metals, sulfur, phosphorus and Halogens, especially chlorine. The inorganic and organic compounds of metals, in particular heavy metals, occupy a special position because

1. the heavy metal compounds occurring in the waste oils or their combustion products are harmful to humans and the environment,

2. the legal limit values for the metal content of heating oils are very low, and

3. The removal of the dissolved and undissolved metal compounds from waste oils down to residual contents of 100 mg of oxide ash / kg of oil has so far been technically hardly possible with reasonable effort, in particular also because of the disruptive carbon in engine oils from diesel engines, which makes filtration as a final cleaning impossible .

The usual processes for the demetallization of waste oils include chemical treatment, followed by separation of the acid and neutralization, possibly followed by thermal treatment, in which volatile components are expelled by distillation.

The waste oils, which are obtained with an average of approx. 7,000 to 10,000 mg and more metal compounds per kg, are only insufficiently freed from the metals in such processes if they are not subjected to vacuum distillation in a final phase.

These methods have the following disadvantages: They are insufficient to reduce the residual metal content to 100 mg / kg (expressed as ash).

They require very high temperatures and vacuum.

The carbon remains in the oil, which results in a low-quality oil, or it can contaminate the equipment excessively, so that an undisturbed process flow is not guaranteed.

They produce very dark oils, which can only be classified as heavy oils.

They can create residues that create additional disposal problems.

The above processes are therefore not suitable for reducing the metal and carbon content of the waste oil in a technically and economically justifiable manner.

US Pat. No. 3,930,988 discloses a method for reducing the ash content in used lubricating oils, in which the lubricating oil with an aqueous solution of ammonium sulfate and / or ammonium bisulfate for reaction with the metal-containing components of the oil and for the formation of metal-containing solids is brought into contact, the reaction mass is separated into an oil phase and an aqueous phase which contains the solids, and the oil phase is obtained as an oil product with a low ash content.

US Pat. No. 3,879,282 discloses a method for reducing the ash content in used motor oils, in which the motor oil is brought into contact with an aqueous solution of ammonium phosphate in order to react with the metal salts contained in the oil. is allowed to sit and the oil is separated from the water and the precipitate.

US Pat. No. 4,151,072 discloses a process for obtaining pure lubricating oil from used lubricating oil, in which the oil with an aqueous solution of an ammonium salt selected from ammonium sulfate, ammonium bisulfate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and mixtures thereof, in sufficient quantities Amount is brought into contact at a temperature of 60 to 120 ° C, the major part of the water and the light hydrocarbons is removed from the mixture obtained at a temperature of 110 to 140 ° C, the oil phase is separated off by filtration, which filtered oil is heated to a temperature of 200 to 480 "C and brought into contact with an adsorbent, the oil thus obtained is stripped at a temperature of 280 to 395" C and then recovered.

The above-mentioned processes are either too complex or do not lead to a sufficient work-up of the waste oil or cannot remove the carbon.

The object of the present invention is to provide a method for working up, in particular for demetallization and

Clearing, to provide waste oil, in which the foreign substances contained in the waste oil, in particular metals and soot, can be removed in a simple technical and economical manner.

This object is achieved by a method of the type mentioned, which is characterized in that

a) the waste oil at temperatures up to 150 "C with an effective amount of an aqueous mixture treated at least two strong acids and / or from at least two salts of two weak bases and two strong acids or precursors thereof,

b) the product obtained is freed from water and cured at elevated temperatures,

c) separates the oil from the solids in the product thus obtained.

Surprisingly, it has been found that the process according to the invention enables waste oil to be processed using small amounts of non-toxic or non-hazardous chemicals without applying pressure at relatively low temperatures. In addition to demetallization and stripping, there is also a sharp reduction in the phosphorus and halogen content of the waste oil. Furthermore, only small amounts of waste occur in the process according to the invention, and there is little oil loss. An oil worked up by the process according to the invention is suitable as a preliminary stage for re-refining since no disruptive dyes are formed.

The process according to the invention is explained in more detail below:

Stage a) of the method according to the invention is preferably carried out in a stripping device. Temperatures of up to 150 ° C., in particular from 20 to 150 ° C., particularly preferably from 100 to 140 ° C., are generally used. The treatment time is preferably 1 to 2 hours. In this stage a) the waste oil is mixed with an effective amount of an aqueous mixture of at least two strong acids and / or at least two salts of two weak bases and two strong ones Acids or precursors thereof treated. The amounts of solution used depend on the foreign substances present in the waste oil and are generally not above the equivalent amount of foreign substances, in particular the metal compounds. The smallest possible amount of solution is preferred for economic reasons. In general, amounts below 5% by weight aqueous solution, based on the waste oil, are sufficient. Amounts below 1.0% by weight are particularly preferably used.

Various acids can be used to treat the waste oil in stage a). An aqueous solution of sulfurous acid, amidosulfuric acid, sulfonic acid, phosphorous acid, hypophosphorous acid, phosphonic acid, hydrochloric acid, hydrofluoric acid or mixtures thereof is preferably used. Sulfuric acid, sulfonic acid, .phosphorous acid and phosphonic acid are particularly preferred.

The weak base and strong acid salt is preferably an ammonium salt of a strong acid. As

Ammonium salts are particularly suitable for ammonium sulfite, ammonium disulfite, ammonium amido sulfate, ammonium sulfonate, ammonium phosphite, ammonium phosphonic acid, ammonium chloride, ammonium fluoride or mixtures thereof. Ammonium sulfite, ammonium sulfonate, ammonium phosphite and ammonium phosphonate are particularly preferred. Mono- and di-ammonium phosphite can be used as the ammonium phosphite.

In step a), a salt of guanidine, an amide, such as carbamide or hydrazine, or else an alkyl or aryl compound of the above acids, or combinations thereof, can also be used.

Stage b) of the method according to the invention is preferably a curation stage. The dissolved and undissolved metal compounds agglomerate with the soot larger particles. The curation temperature is preferably 150 to 300 ° C and the treatment time 0.5 to 24 hours, particularly preferably 2 to 12 hours.

The curation can be carried out in such a way that the oil is heated in stages using special heat exchangers, for the most part remaining in the respective circuit. In this stage, the metal compounds are precipitated and various organic acids are reduced to carbon.

In the subsequent step c) of the process according to the invention, the product obtained is separated from the solids. Since it is easy to sediment, it can, for example, be decanted, about 95% of the solids being separated off. Depending on the viscosity, the oil can then be reheated somewhat, for example to a temperature of 60 to 150 ° C., and then filtered, for example pressed through a filter press. The remaining solids are removed. The mixture can also be pressed directly through a filter press.

If appropriate, the mixture obtained in stage a) can be kept at elevated temperature before the curation and, for example, by adding an additive for better removal of the oil in stage c), preferably at a temperature of 140 to 200 ° C. and above 1 to 2 Hours to be treated. The additives used are preferably sodium, potassium or calcium hydroxide, sodium, potassium or calcium alcoholate, a sodium, potassium or calcium salt from an organic acid, such as sodium ethylate or sodium stearate, urea, hydrazine, guanidine and a carbazide or a salt of this compound is used. Such a holding level shortens the subsequent curation period. Before the waste oil is treated by the process according to the invention, any customary pretreatment can be carried out. For example, a pre-dewatering, such as by centrifuging, decanting or distilling, can be carried out with a proportion of more than 5% of foreign substances.

The oil prepared by the method according to the invention is particularly suitable for use as heating oil and bunker oil or as a base oil for the renewed production of lubricating oils.

The following examples illustrate the invention:

example 1

A mixture of 2.5 g of diammonium sulfite and 1.5 g of guanidine glycerophosphonate in 10 g of water was added to 250 g of a waste oil mixture of used motor oils (diesel and petrol engines) containing 0.84% ash and 3% water at 100 ° C.

After stirring at 95 ° C for 10 minutes, the mixture was heated and held at 140 to 150 ° C for 1 hour, then slowly heated to 250 ° C and held for 2 hours, cooled and filtered. The filtrate, a golden brown, clear oil, still contained 0.01% ash.

Example 2

300 g of a marine diesel drain oil with an ash content of 1.14% and a soot content of approx. 2.5% were mixed with a neutralized mixture of 0.5 g hypophosphorous acid and 1.5 g phosphorous acid with ammonium hydroxide solution and 2.4 g guanidine-toluene sulfonate "C and added slowly with stirring heated to 150" in 15 g of water at 50 C and held there for one hour and further heated to 220 ^β C, cooled to 120 ° C and filtered. The filtrate was a golden yellow clear oil with an ash content of 0.01%. The dry residue contained all carbon in addition to the metal salts and totaled 4% based on the oil mass.

Example 3

500 g of bilge oil from river navigation with an ash content of 0.52% and 10% water was mixed with a solution of 1.6 g monoamonium phosphite and 1.6 g guanidine toluene sulfonate in 10 g water at 95 ° C after Stirring heated to 150 ° C for 10 minutes and held at 140 ° C for 1 hour, heated to 190 ° C and held for 12 hours, slightly cooled and filtered. The clear filtrate still contained 0.025% ash.

Claims

P a t e n t a n s r u c h e

^{1 <} - ⁾ l. Process for working up, in particular for demetallizing and deburring waste oil, characterized in that

* A) the used oil at temperatures up to 150 ° C with an effective amount of an aqueous solution treated 5 of a mixture of at least two strong acids and / or of at least two salts of a weak base and a strong acid or precursors thereof ^0,

b) the product obtained is freed from water at elevated temperatures and cured and

25 c) separates the oil from the solids in the product thus obtained.

2. The method according to claim 1, characterized in that stage a) is carried out in a stripping device 0.

3. The method according to claim 1 or 2, characterized gekennzeich¬ net that step a) is carried out at a temperature of 20 to 150 ° C. 5

4. The method according to any one of claims 1 to 3, characterized in that step a) is carried out over 1 to 2 hours.

5. The method according to any one of claims 1 to 4, characterized in that step a) is carried out with an amount of up to 5% by weight of the aqueous solution, based on the waste oil.

6. The method according to any one of claims 1 to 5, characterized in that step a) is carried out with an aqueous solution of at least two acids selected from sulfurous acid, sulfamic acid, sulfonic acid, phosphorous acid, hypophosphorous acid, phosphonic acid, hydrochloric acid and hydrofluoric acid becomes.

7. The method according to any one of claims 1 to 5, characterized in that step a) is carried out with an aqueous solution of at least two ammonium salts of a strong acid or precursors thereof.

8. The method according to claim 7, characterized in that the ammonium salt used is ammonium sulfite, ammonium disulfite, ammonium amido sulfate, ammonium sulfonate, ammonium phosphite, ammonium phosphonic acid, ammonium chloride or ammonium fluoride.

9. The method according to any one of claims 1 to 5, characterized in that step a) with an aqueous

Solution of a guanidinium salt, an amide, an alkyl or aryl compound of a strong acid or a precursor thereof is carried out.

10. The method according to any one of claims 1 to 9, characterized characterized in that stage b) is carried out at a temperature of 150 to 300 ° C.

11. The method according to any one of claims 1 to 10, characterized in that step b) over 0.5 to 24

Hours.

12. The method according to any one of claims 1 to 10, characterized in that step b) is carried out over 2 to 12 hours.

13. The method according to any one of claims 1 to 12, characterized in that step c) is carried out by sedimentation and / or filtration.

14. The method according to any one of claims 1 to 13, characterized in that step c) is carried out at a temperature of 60 to 150 "C.

15. The method according to any one of claims 1 to 14, characterized in that a conventional pre-cleaning of the waste oil is carried out before step a).

16. The method according to claim 15, characterized in that the preliminary cleaning is carried out by dewatering.

17. The method according to any one of claims 1 to 16, characterized in that the product of step a) is kept at elevated temperature before curation.

18. The method according to claim 17, characterized in that the holding step is carried out by treating the product of step a) with at least one additive to improve the separability of the oil in step c).

19. The method according to claim 17 or 18, characterized gekenn¬ characterized in that the holding step is carried out at a temperature of 140 to 200 ° C.

20. The method according to any one of claims 17 to 19, characterized in that the holding step is carried out over 1 to 2 hours.

21. The method according to any one of claims 17 to 20, characterized in that as an additive sodium, potassium or calcium hydroxide, sodium, potassium or calcium alcoholate, a sodium, potassium or calcium salt with an organic acid, urea , Hydrazine, guanidine, a carbazide or a salt of these compounds is used.