EP0377606A1

EP0377606A1 - Process for purifying and regenerating used oils.

Info

Publication number: EP0377606A1
Application number: EP88907226A
Authority: EP
Inventors: Adekunle Onabajo
Original assignee: Individual
Current assignee: RWE Entsorgung AG
Priority date: 1987-08-19
Filing date: 1988-08-18
Publication date: 1990-07-18
Anticipated expiration: 2008-08-18
Also published as: JPH02504523A; EP0377606B1; WO1989001508A1; AU2269788A; CN1045122A; RU1834902C; DE3876245D1; US5141628A; DE3890632D2; CN1021233C

Abstract

On mélange des huiles usées, notamment des huiles lubrifiantes usées, après leur filtrage grossier, à une solution aqueuse de verre soluble et à une solution aqueuse de polyalkylène-glycol, en les agitant a une température élevée. On laisse ensuite le mélange ainsi obtenu se déposer, on en sépare le matériau sédimenté et on sépare l'eau et la fraction de bas point d'ébullition de la phase huileuse par distillation. On peut soumettre la phase huileuse sèche ainsi obtenue à une adsorption de filtrage, directement ou après un traitement en soi connu avec une dispersion de sodium, puis à un fractionnement par distillation.Used oils, especially used lubricating oils, after their coarse filtering, are mixed with an aqueous solution of water glass and an aqueous solution of polyalkylene glycol, with stirring at an elevated temperature. The mixture thus obtained is then allowed to settle, the sedimented material is separated therefrom and the water and the low boiling point fraction from the oily phase are separated by distillation. The dry oily phase thus obtained can be subjected to filter adsorption, directly or after treatment known per se with a sodium dispersion, then to fractionation by distillation.

Description

Process for cleaning and regeneration of waste oils

The invention relates to a process for cleaning and regenerating used oils, in particular used lubricating oils, by filtration, heat treatment and stripping of the low boilers consisting of solvent and water.

10

Waste oils are used mineral oils, especially used engine and lubricating oils. The utility value of mineral lubricating oils is greatly affected by oxidation products, pollution _τf - and other _additives that accumulate during use. Products of this type no longer fully fulfill their task and must be replaced. They are referred to as waste oils and are collected for reasons of environmental protection, raw material conservation and also from an economic point of view

20 worked up. Old oils mainly consist of a base oil based on mineral oil or synthetic oil, but contain considerable amounts of foreign matter, e.g. B. water, solvents, fuels, asphalt-like substances, acids, resins, ashes and additives such as antioxidants, anti-corrosion agents,

25 wetting agents, dispersing agents, anti-foaming agents and viscosity index improvers. The additives can contain halogen, sulfur and nitrogen compounds and numerous other, sometimes toxic, components.

3.0

Waste oils are first cleaned mechanically by removing undissolved impurities and foreign substances by sedimentation, filtration or centrifugation. The Ab-

35 Separation can be accelerated considerably by heating the used oil to 50 to 100 ° C.

The conventional regeneration of waste oils takes place in a multi-stage process, as described in Ullmann's Encyklopadie der technical chemistry 4th edition, volume 20 page 498. After the rough removal of water and solid foreign substances, low-boiling fractions and residual water are removed by atmospheric distillation at about 250 ° C., then oxidation products and additives are removed by sulfuric acid refinement with subsequent lime neutralization, and the refining sludge is separated off by decanting or filtering. The division into one or two light or medium-viscosity distillate and residue fractions is carried out by vacuum distillation at 80 to 100 mbar, and finally the fractions are lightened and stabilized by bleaching earth treatment.

According to the PROP process from Phillips Petroleum Co., as described in Hydrocarbon Processing, September 1979, pages 148 ff., Waste oil is subjected to a refining hydrogenation over nickel-molybdenum catalysts after pretreatment with an aqueous diammonium phosphate solution. Although polychlorinated biphenyls are also said to be at least partially degraded in this process, chlorinated solvents and cleaning liquids, metalworking oils and other processing oils and their composition are intended for the regeneration of this process is not clearly identified, and insulating and transformer oils have not been obtained in the feed material. Suitable used products for this process are therefore essentially used engine oils.

According to the KTI process from Kinetics Technology International, the waste oil is freed of water and dirt by sedimentation and residual water and low boilers by atmospheric distillation. The gas oil fraction is then separated off in a separate stage. In the following vacuum distillation, the lubricating oil components are fractionated, condensed and dirt, additives and part of the oxidation products removed as a sump. The distillates are hydrofinished and stripped. Since acid refining is also absent in this process, additives or foreign components must either be separable by distillation or convertible by hydrogenation. Ingredients must not impair the activity of the hydrogenation catalyst, so that, for. B. Cutting oils with contents of halogenated hydrocarbons cannot be processed by this method either, see Ullmanns Encyklopadie der technical chemistry, 4th edition volume 20, page 500.

In the recycling process, the oxidation products and additives are likewise not removed with sulfuric acid, but rather by treatment with finely dispersed sodium, as a result of which they either polymerize or are converted into sodium salts which have such a high boiling point that the oil distils become can. The distillation takes place in two steps, the second of which is designed as a short-path thin-film evaporation for separating the reaction products.

The known methods are therefore both very expensive and inadequate for the waste oil mixture which is brought together at the collection points for regeneration and contains any components.

The invention has for its object to develop a universally applicable method that allows pollutants and other undesirable components from used lubricating oils and other waste oils with higher product yields and higher product quality with less process effort and in particular less landfill than according to the prior art the technology possible to remove. The process should in particular be suitable for special treatments, the hydrogenation or, for example, the treatment with sodium, and to bring about procedural simplifications and the associated cost reductions, for example by avoiding the catalyst poisoning when the hydrogenation stage is switched on.

This object is achieved according to the invention by either collecting waste oils after coarse filtration

(1) heated to a temperature of 50 to 100 ° C. in a closed stirrer and mixed with 0.5 to 2.5% by weight of an aqueous alkali water glass solution with a water content of 30 to 70, based on the waste oil, with intensive stirring % By weight, based on the solution, and 0.25 to 2.5% by weight of one aqueous solution of a polyalkylene glycol of the formula

R0- (CH-CH "-0) -R

| ^{2 n} i

^R 1 with R = n-alkyl having 8 to 20 carbon atoms, R- = hydrogen, alkyl having 1 to 3 carbon atoms, n = 20 to 125 and an average molecular weight of 1,000 to 10,000, and a water content of 80 to 97, 5% by weight, based on the solution, or

heated to a temperature of 60 to 80 ° C., in particular in the range of 70 ° C., and mixed with 0.5 to 2.5% by weight of an aqueous alkali water glass solution with a water content of 40, based on the waste oil, with intensive stirring to 60% by weight, based on the solution, and 0.25 to 2.5% by weight of an aqueous solution of a polyalkylene glycol of the formula

R2_0- (CIH-CH2, -0) nR2_ _I_I

CH ₃ with R ₇ = n-alkyl having 10 to 14 hydrocarbon atoms, preferably C _j -H- ^ n = 21 to 30 and an average molecular weight of 2,000 to 5,000 with a water content of 80 to 97.5% by weight , based on the solution,

(2) the mixture obtained can settle in a decanter at 70 to 90 ° C, the sedimented material separated and

(3) from the oil phase at a temperature of 100 to 140 ° C and a pressure of 20 to 100 Torr separates the low boilers consisting of water and solvent. In process step (2), dewatering takes place in particular. The feedstocks bind the water as a residue, which is then removed in a known manner by separation. 50 to 80% of the free water present in the waste oil is separated in this way. The residual water and the low boilers are then removed by distillation in process stage (3). The waste oil treatment according to process steps (1) to (3) is carried out in a temperature range from 50 to 140 ° C., temperatures as low as possible in this range are preferred. In stage (3), PCB accumulation in the low boilers and water is excluded because the boiling point range of polychlorinated bi- and terphenyls is above the stripping temperature. PCB is therefore not removed in process stage (3), which ensures that the low boilers and water obtained by this process are not contaminated with PCB. This is of great importance for an environmentally friendly process for waste oil processing.

Process stage 3 can also be carried out before process stage 2 by first separating the low boilers from the mixture obtained, then letting them settle in a decanter and finally separating the sedimented material.

Preferably, in process stage (1) the alkali ^'wass rglaslosungen and / or the Polyalkylenglykollösungen preheated, in particular to 30 to 60 ° C, preferably to about 50 ° C. According to a further embodiment of the process according to the invention, the oil phase pretreated according to process steps (1) to (3) is treated further by:

(4) the oil phase at a temperature of 30 to 120 ° C with 3 to 8 parts by weight of n-alkanes with 6 to 10 carbon atoms to 1 part by weight of the pretreated oil phase, while maintaining the temperature for a while stirring vigorously, the mixture obtained settles in a decanter at room temperature, separates the sedated material, treats the oil phase in an adsorber with filter insert, the filter insert containing bleaching earth or compacted aluminum oxide, and

(5) the low boilers (n-alkanes) are separated off from the oil filtrate obtained at a temperature of 50 to 80 ° C. and a pressure of 20 to 100 torr.

A further embodiment of the process according to the invention, in particular for the treatment of waste oils containing polychlorinated bi- and terphenyls, consists in further treating the oil phase pretreated by process steps (1) to (3) by (6) pretreating the waste oil phase a temperature of 70 to 120 ° C. is heated in a closed agitator and 3 to 8 parts by weight of n-alkanes with 6 to 10 carbon atoms are added to 1 part by weight of the pretreated waste oil phase, with intensive stirring, based on the pretreated waste oil phase, 0 , 1 to 0.5% by weight of an aqueous alkali water glass solution with a pH of -9 and 0.1 to 0.5% by weight of polyalkylene glycol of the general formula

HO- ( with ₃ = hydrogen or methyl, n = 9 to 22, a hydroxyl number of 100 to 300 mg KOH / g according to DIN 53240 and an average molecular weight of 380 to 1,050, while maintaining the temperature for a while, 15 to 120 minutes, in particular 30 to 100 minutes and preferably about 50 to 60 minutes, stirred vigorously, 0.1 to 0.25% by weight of anhydrous alkali metasilicate, based on the altol phase, is added, stirring is continued for 5 to 15 minutes,

(7) the mixture obtained is allowed to settle in a decanter at room temperature and the sedimented material is separated off,

(8) the oil phase is treated at a temperature of ^' 3E-60 ° C in an adsorber, preferably a percolate adsorber, with a filter insert, the filter insert bleaching earth or compacted

Contains aluminum oxide, and

(9) the low boilers (n-alkanes) are separated off from the oil filtrate at a temperature of 50 to 80 ° C. and a pressure of 20 to 100 torr.

In process stage (6), preference is given to using 0.1 to 0.5% by weight, based on the altol phase, of polyethylene glycol of the general formula

IV H0- (CH ₂ -CH ₂ -0) _n -H, with n = 9 to 22, a hydroxyl number of mg KOH / g 100 to 300 and in particular 170 to 210 according to DIN 53240 and an average molecular weight of 380 to 1050 , and in particular 480 to 650, and 3 to 8 parts by weight of n-alkanes with 6 to 10 carbon atoms per 1 part by weight of the pretreated oil phase.

In a further embodiment of the process according to the invention, a hydrogenation treatment step known per se can be switched between process step (3) and process step (4), in which, in the presence of a hydrogenation-active catalyst, in particular at 200 to 400 ° C. and 10 to 200 bar and preferably at 300 up to 380 ° C and 40 to 60 bar the pretreated oil phase is hydrogenated. However, this inclusion of known hydrogenation processes will generally only make economic sense if the process according to the invention is to be used in an already existing hydrogenation plant.

The filter insert of process stage (4) or (8) is regenerated if necessary by washing it free of the adsorbed material with a solvent. A ketone solvent is preferably used for this purpose, which in particular consists of one or more solvents each having a boiling point of 50 to 80 ° C. and is in particular acetone or methyl ethyl ketone.

• • • According to a further embodiment of the invention

In the process, the treated oil phase is finally subjected to vacuum distillation at a temperature of 200 to 300 ° C. and a pressure of 1 to 50 torr.

To treat waste oils which contain polychlorinated bi- and terphenyls, a further embodiment of the process according to the invention provides for treatment of the dry oil phase (with water content -ζ 0.1% by weight) after process step (3) in a manner known per se .%) with finely dispersed sodium. Process stages (1) to (3) are able to deliver a constant water-free oil flow, which is the most important requirement for the use of sodium. Since the oxidation products and the non-PCB chlorine compounds are largely removed by the pretreatment in this water-free oil stream, the sodium process is economically viable.

The sodium required for the waste oil treatment is added to the pretreated waste oil in the form of a dispersion, in particular consisting of sodium particles of 5 to 10 μm in a base oil of a similar composition to motor oils. For this purpose, in a gator dispersants sodium in an oil, preferably Reraffinat, listed • melted ^'and finely divided, so that Teilchengrδßen of -ζ be achieved microns 20th A dispersion of 33% by weight sodium is particularly suitable for the treatment of the pretreated dry oil stream. The amount of dispersion added is matched to the content of inorganic chlorine. The treatment temperature and time depend on the quality of the dry oil. Normally, one can be in a temperature range from 20 ° C to 250 ° C and in particular in a temperature range from 100 to 200 ° C and in a period of 1 to 30 minutes reliable PCB separation can be achieved.

Treatment of the waste oil with sodium produces sodium chloride, contaminated with metal oxides, metal carbonates and metal sulfates. These oily solids are separated, for example by sedimentation in a separator or decanter. The oil phase, which is now free of PCBs and chlorine, is subjected to the treatment according to process stage (4) and then distilled.

10

The method according to the invention is a mild and environmentally friendly method. At the same time, an inexpensive and simple process and apparatus technology is guaranteed. Several physical and chemical processes run in parallel in the individual process steps of the pretreatment. Both the removal of all pollutants and the preparation run under mild process conditions. Here the - ₀ "filtering adsorption" is of particular importance for the cleaning of the material to be regenerated. The method steps of the method according to the invention are:

- Flocculation and conversion of dispersed contaminants

- Adsorption and sedimentation of the flocculated and unconverted contaminants

- filtering adsorption for the selective separation of dissolved and undissolved finely dispersed impurities such as Degradation products, oxidation products, additives

0

5 I

- Distillation or stripping of the substances outside the boiling range of the lubricating oils

5 The base oil obtained is characterized by a cheaper and higher viscosity index than fresh oil. All ash-forming additives - otherwise causing sludge formation - are removed. H. the ash content is practically 0% by weight. The viscosity improvement additives are largely retained, namely at least 1/3 of the corresponding additives of the fresh additive package.

Contaminants in used oil form stable dispersions due to the presence of detergents. Additives prevent the physical separation of the contaminants by gravity and / or centrifugal force. According to the invention in process step (1) the flocculants and adsorbents, namely alkali water glass and polyalkylene glycol of the formula given, destabilize the dispersion. The differences in density between the oil and foreign matter phases thus take effect. At the same time, the chlorine compounds are chemically converted and NaCl and non-chlorinated compounds are formed. The oxidation products are neutralized and 5 the converted and neutralized products are adsorbed.

In process stage (2), impurities and the flocculants and adsorbents are separated off. The flocculated, dispersed impurities are eliminated by decanters or separators as a result of the destabilization which took place in stage (1) and the density differences which became effective in stage (1) by the action of gravity or minimal centrifugal forces. 5 In process stage (3), the low boilers, namely polar and non-polar solvents, and water are removed.

The solvent and adsorbent additive in process stage (6) serves for the further precipitation of finely dispersed impurities, in which case these additives bring about the removal of polychlorinated bi- and terphenylene and the solvent additive supports the subsequent stage of the filtering adsorption. If no polychlorinated bi- and terphenyls are present, the addition of the n-alkanes can be used to go directly to the filtering adsorption stage without the further addition of adsorbents - see process stage (4).

Process stage (6) with the addition of solvent and adsorbent is followed by process stage (7), which largely corresponds to process stage (2).

The filtering adsorption takes place in process stage (8) or (4). In this stage, the remaining dissolved and undissolved impurities and undesired residual additives are specifically bound to the adsorbents. The lubricating oil components (hydrocarbons) pass through the adsorbents. This filtering adsorption is a multi-parameter separation method, which is characterized in that two chemically different substances or two chemically different groups of substances are separated from one another due to their different adsorption capacity, by allowing a specific solvent and an adsorbent to act on the mixture. Compared to conventional filtration, the filtering adsorption differs in that there is only a single phase during the separation, while the filtration requires two phases, generally solid / liquid. Compared to the normal Adsorption is the 'filtering adsorption distinguished by its selectivity, which is achieved by the selective solvent and a selected adsorbent, here bleaching earth or compacted aluminum oxide, see "Filtering adsorption", W. Fuchs, F. Glaser and E. Bendel, chemistry -Engineering technology 1959, pages 677 679.

Adsorbed material, namely 5 to 10% by weight of finely dispersed, dissolved oxidation products and residual additives, are desorbed with suitable solvents, solvents with a boiling point of up to 80 ° C., in particular acetone or methyl ethyl ketone. The adsorbent is dried at about 60 to about 120 ° C., preferably about 100 ° C., under a protective gas, preferably nitrogen, and then brought to the temperature required for process step (8). The adsorbent is now ready for use again and can be used continuously at these values.

The lubricating oil components (about 1.5% by weight) contained in the adsorbent are removed by solvent rinsing, in particular with n-heptane, before regeneration of the adsorbent (with acetone or methyl ethyl ketone) and process step (6) or ( 9) fed. This step serves to increase the yield of the regrind.

The residual additives and oxidation products obtained after evaporation of the solvent can be found as additives e.g. for asphalt processing use.

PCBs, chlorinated dioxins, furans and aliphates with chlorine levels ^ 5% can be degraded in this way to below the detection limit. The recovered solvent is used again for solvent rinsing. In process step (5) or (9), the solvent is separated from the regenerate and returned in step (4) or (6).

If the oil phase finally obtained is a mixture of lubricating oil fractions with different flash points and viscosities, the fractions have to be separated under vacuum and temperatures above 200 ° C. The swamp is base oil.

1 The process comprising process steps (1) to (3) can be used for decentralized waste oil processing, in that the collected waste oils are brought together in area collection points and treated in decentralized small plants according to the process comprising process steps (1) to (3) as a partial process . The thus treated waste oil may then in a central large-scale plant the method according to one or more of the dependent claims in particular for removing chlorine compounds and per- J- _Q chlorinated bi- and terphenyls are subjected.

The following ingredients are preferred: 1. As an alkali water glass

Sodium water glass 50/51 in process step (1) and 15 process step (6), alkaline, filtered

Analysis values H_0 54.4 - 55.4%

Si0 ₂ 30 - 30.5%

- Na ₂ 0 14.6 - 15.1% lχ mPas / 20 ° C 400 - 600

20; kg / m ³ , 20 ° C 1530.

Sodium water glass 58/60 in process stage (1), filtered

H ₂ 0 45.5%

Si0 ₂ 36.5%

25 a ₂ 0 18.0% o kg / m ³ , 20 ° C 1710

2. as alkali metasilicate in process step (6), water-30 free

Analytical values

Si0 ₂ 48 + .1, 0%

Na ₂ 0 51 + _ 1.0%

35 3. as polyalkylene glycol (non-ionic) in process stage (1) polypropylene glycol with C. ₂ H _{25 end} groups, average

• • • molecular weight 2,000 to 10,000

Solutions effective in the concentration range 2.5 to 20% by weight.

4. as polyalkylene glycol in process stage (6) polyethylene glycol (PEG)

Hydroxyl number 100 to 300 mg KOH / g according to DIN 53240 with average molecular weight 380 to 1050.

5. as solvent in process steps (4) and (6) n-alkanes, C_ - C. -, especially n-heptane, technical product.

6. as adsorbents in process stages (4) and (8) TONSIL CCG 30/60 mesh and TONSIL LFF 80 particle size distribution: wide ^ 0.25 mm to 0.55 mm chemical composition:

Si0 ₂ , Al ₂ 0 ₃ , Fe ₂ 0 ₃ , MgO, CaO, a ₂ 0 and K ₂ 0.

COMPALOX, compacted aluminum oxide grain size 1.5 to 5 mm specific surface 180 to 200 m ² / g chemical composition:

Al ₂ 0 ₃ (92%), Si0 ₂ (0.01 - 0.02%), Fe ₂ 0 ₃ (0.01 -

0.03%, Na ₂ 0 (0.4 - 0.6%)

Adsorbent regeneration with acetone, methyl ethyl ketone (technical).

Filters used: stainless steel, sieve mesh 20 μm to 200 μm; Glass fiber filter and non-woven filter. I

The following examples serve to explain the invention.

5 Example 1

After coarse filtration, 95 parts of waste oil from a mixture of collection points were heated to a temperature of 70 ° C. in a closed agitator and, with intensive stirring, based on the waste oil with 2.5% by weight of each

J. _Q preheated to 50 ° C aqueous alkali water glass solution 58/60 with a

Water content of 54% by weight, based on the solution, and 2.5% by weight of an aqueous 20% by weight polypropylene glycol solution (average molecular weight 3,000) preheated to 50 ° C. and having a water content of 80%. %, based on the solution. The mixture became

, - _P - after the addition of the starting materials, continue to stir intensively for 30 minutes at 80 ° C. The mixture obtained was sedimented in a decanter at 70 ° C with a throughput of 3,000 ml / h and the oil phase separated. The low boilers and the residual water became from the oil phase

20 separated at a temperature of 130 ° C and a pressure of 50 torr.

Example 2

Waste oil not containing PCBs was treated with n-heptane in the ratio of oil phase to n-heptane of 1: 4 parts by weight in a closed stirrer, as specified in Example 1, in the dry oil phase, and the mixture was stirred vigorously at 40 ° C. for 30 minutes . The oil solution was then in a decanter at 10 to 20 ° C with a throughput of 12,000 ml / h

30 sedimented, and then separated the oil solution from the precipitation residue.

Example 3

PCB-containing used oil was in a closed agitator, _., _. after the addition of n-heptane in the ratio of oil phase to n-heptane of 1: 4 parts by weight to the oil phase pretreated according to Example 1, with intensive stirring at 80 ° C. with a mixture of 0.25% by weight preheated to 50 ° C. Soda water glass 50/51 (alkaline) and 0.1% by weight of polyethylene glycol (average molecular weight 600, OH number 170 mgKOH / g), each based on the dry oil phase. The mixture was stirred intensively at 70 ° C. for about 110 minutes. Then 0.1% by weight of anhydrous sodium metasilicate was added and the mixture was stirred for a further 10 minutes. The oil solution was sedimented in a decanter at 10 to 20 ° C. with a throughput of 12,000 ml / h and the oil solution was separated from the residue. Q

Example 4

The oil solution from Examples 2 and 3 was subjected to a "filtering adsorption". The adsorbers consisted of a stainless steel mesh (20 - 40 micron) and an adsorber _j - benspackung with bleaching earth Tonsil CCG 30/60. The undesired oil components were adsorbed at 40 ° C. It was regenerated with n-heptane. The throughput of regenerated solution was 3,000 ml / h. The solvent n-heptane was recovered from the regenerate solution by distillation at 70 ° C. and a pressure of 50 torr.

The regenerate obtained was a mixture of lubricating oil fractions with different flash points and viscosities. The fractions were separated under vacuum at 5 250-300 ° C and a pressure of 1 to 10 Torr. The bottom was obtained as the bottom.

In the meantime, the adsorber has been regenerated by desorbing the adsorbed impurities (oxidation products, unwanted residual additives, degradation products, etc.) at 50 ° C with acetone (boiling point 56 ° C). The adsorber was dried under nitrogen flow at 60 ° C and made reusable.

5 The acetone solution obtained was subjected to distillation in order to free the waste from the acetone. The acetone was used again.

Example 5

The wastes from Examples 1, 2, 3 and 4 were used as additives in the concentration range 0.5 to 5% by weight (based on bitumen) for asphalt modification.

Instead of process stage (4) or (8), thin-film evaporation known per se can be carried out. Likewise, following the treatment with dispersed sodium, the oil phase obtained can be subjected to thin-film evaporation instead of process step (4).

The process according to the invention is distinguished from the processes of the prior art by numerous advantages: high economic efficiency, high operational reliability, mild treatment process, enabling decentralized disposal, partial integration into existing systems and processes, residues of the process, either completely reusable as additives or valuable materials for other products or traceable to previous process stages.

The base oil obtained was characterized by a cheaper and higher viscosity index than the fresh oil. All ash-forming additives - otherwise causing sludge formation (in particular in the engine) - are removed, ie the base oil obtained has an ash content of almost 0.0% by weight. Finally, the additives to improve the viscosity are largely retained, in accordance with previous ones 1

Results at least about a third of the content of these additives in the fresh additive package.

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20th

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Spare sheet

Claims

1. Process for cleaning and regeneration of waste oils based on mineral oil by filtering, heat treatment and stripping off the low boilers consisting of solvent and water, characterized in that waste oils after coarse filtering (1) to a temperature of 50 to 100 ° C. in a closed agitator heated and under intensive

Stirring, based in each case on the waste oil, mixed with 0.5 to 2.5% by weight of an aqueous alkali water glass solution with a water content of 30 to 70% by weight, based on the solution, and 0.25 to 2.5% by weight an aqueous solution of a polyalkylene glycol of the formula

with R = n-alkyl with 8 to 20 carbon atoms, R ₁ = hydrogen, alkyl with 1 to 3 carbon atoms, n = 20 to 125 and an average molecular weight of 1,000 to 10,000, and a water content of 80 to 97.5% by weight .%, based on the solution, or

heated to a temperature of 60 to 80 ° C in a closed agitator and mixed with intensive stirring, based in each case on the waste oil, with 0.5 to 2.5% by weight of an aqueous alkali water glass solution with a water content of 30 to

70% by weight, based on the solution, and 0.25 to 2.5% by weight of an aqueous solution of a polyalkylene glycol of the formula

RO- (CH-CH - O) -R- ² | ^{2 n 2} II,

CH ₃ with R_ = N-alkyl having 10 to 14 carbon atoms, n = 21 to 30 and an average molecular weight of 2,000 to 5,000 with a water content of 80 to 97.5% by weight, based on the solution, (2) the the resulting mixture can settle in a decanter at 70 to 90 ° C, the sedimented material is separated and (3) from the oil phase at a temperature of 100 to.

140 ° C and a pressure of 20 to 100 Torr separates the low boilers consisting of water and solvent.

2. The method according to claim 1 d a d u r c h g e k e n n z e i c h n e t that the oil phase pretreated by the process steps (1) to (3) is further treated by (4) the oil phase at a temperature of 30 to

120 ° C with 3 to 8 parts by weight of n-alkanes with 6 to 10 carbon atoms added to 1 part by weight of the pretreated oil phase, stirring vigorously for a while while maintaining the temperature, the resulting mixture is allowed to settle in a decanter at room temperature, the sedimented material separated, the oil phase treated in an adsorber with a filter insert, the filter insert containing bleaching earth or compacted aluminum oxide, and (5) from the oil filtrate obtained at a temperature of 50 to 80 ° C. and a pressure of 20 to 100 torr Separates low boilers. I

3. A process for the treatment of Altδlen containing polychlorinated bi- and terphenyls, characterized in that the oil phase pretreated by process steps (1) to 5 (3) of claim 1 is further treated by (6) pretreating the altol phase at a temperature heated from 70 to 120 ° C. in a closed agitator and mixed with 3 to 8 parts by weight of n-alkanes Q with 6 to 10 carbon atoms to 1 part by weight of the pretreated altol phase, with intensive stirring, based on the pretreated altol phase, 0.1 up to 0.5% by weight of an aqueous alkali water glass solution with a

X5 pH = 9 and 0.1 to 0.5% by weight of polyalkylene glycol of the general formula

H0- (CIH-CH, -0) n-H _I_I_I,

R. z with R ₃ = hydrogen or methyl, n = 9 to 22, a hydroxyl number of 100 to 300 mg KOH / g according to DIN 53240 and an average molecular weight of 380 to 1,050, stirring intensively for 15 to 120 minutes while maintaining the temperature, 0.1 to 0.25

25% by weight of anhydrous alkali metasilicate, based on the waste oil phase, is stirred for another 5 to 15 minutes,

(7) the mixture obtained is allowed to settle in a decanter at room temperature, and the sedimented material is separated off,

30

(8) treating the oil phase at a temperature of 30 to 60 ° C in an adsorber with a filter insert, the filter insert containing bleaching earth or compacted aluminum oxide, and

(9) from the oil filtrate at a temperature of 50 to

35

80 ° C and a pressure of 20 to 100 Torr separates the low boilers.

4. The method of claim 3, d a d u r c h g e k e n n z e i c h n e t that in process step (6), based on the Altolphase, 0.1 to 0.5 wt.% Polyethylene glycol

5 of the general formula

H0- (CH - CH_-0) -H IV,

2 2 n with n = 9 to 22, a hydroxyl number of 100 to 300 mg KOH / g according to DIN 53240 and an average molecular weight of 380 to 1,050, - and 3 to 8 parts by weight of n-alkanes with 6 to 10 carbon atoms 1 part by weight of the pretreated oil phase is used.

15 5. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the treated oil phase finally a vacuum distillation at a temperature of 200 to 300 ° C and a pressure of 1 to 50 Torr under-

20. throws.

6. The method according to any one of claims 1 or 2, d a d u r c h g e k e n n z e i ch n e t that one after process stage (3) in known per se

25 Treat the pretreated, dry

Oil phase with finely dispersed sodium by in a reactor the oil phase with a sodium / oil dispersion consisting of finely dispersed sodium particles in a base oil,

30 mixed at a temperature of 100 to 250 ° C, the oily solids formed separated, the oil phase is subjected to the treatment according to process step (4) and then distilled.

35 7. The method according to any one of claims 2 to 6, characterized in that the process step (4) is replaced by a thin film evaporation.

8. The method according to any one of claims 1 to 4, characterized in that after process step (3) a Hydrierbe¬ treatment in the presence of a hydrogenation-active catalyst, in particular at 200 to 400 ° C and 10 to 200 bar, and preferably at 300 to 380 ° C and 40 to 60 bar and then distilled.

10

9. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n t that the alkali water glass solution and / or the polyalkylene glycol solution £ 5 preheated, in particular to 30 to 60 ° C, preferably preheated to about 50 ° C, used in process step (1).

10. The method according to one of the preceding claims, that a d u r c h g e k e n n z e i c h n e t,

20 that process step (3) before the process step

(2), namely first separating the low boilers from the mixture obtained, then allowing them to settle in a decanter and finally separating the sedimented material.

25

SO

35