FR2530656A1 - Process for the treatment of spent oils to regenerate them. - Google Patents

Abstract

Recovery of nonalimentary reclaimable oils from spent oils, especially from mineral oils. According to the invention the spent oil is subjected to stirring in a strong inorganic acid medium and then with an organic compound containing a benzene nucleus and a product containing an alcohol or derived functional group, or else with an alcohol (or derivative) of the aromatic type; the benzene-type compound may be a surface-active agent of ionic or nonionic type. The regenerated oil is recovered in the form of a supernatant phase in a phase separation, preferably while hot. Application to spent oils of various types in the industrial field.

Description

 The present invention relates to the field of oily products, in particular mineral oils. It especially relates to a process for treating used oils with the aim of recovering, from such residues, a recoverable oil.

 Used oily products, generally considered as bulky waste, represent considerable tonnages in the various fields of use such as for example: engine drain oils and gearboxes for various vehicles, - oils from mechanical machines or devices electrical, various industrial oils, liquid or semi-fluid waste of fatty substances, etc.

 Currently, this oily waste is either largely burnt or subjected to various regeneration treatments. For example, in accordance with a known method, the contaminated oil is dehydrated by heating to a temperature of approximately 150-160 ° C. then subjected to a treatment with concentrated sulfuric acid which provides on the one hand, after filtration and heating to 3000 ° C. , a regenerated oil type VEDOL or the like and, on the other hand, a muddy residue of blackish color called "acid mud" whose volume represents at least 30% of the product recovered after sulfuric treatment.

 Such recovery processes for contaminated oils require the implementation of several treatment phases and the use of expensive and / or dangerous products.

 According to other techniques, the purification of waste oils has been recommended by aqueous suspension and the addition of flocculating or dispersing agents constituted by ionic or nonionic desupotymers or copolymers, alone or with certain surfactants (US Pat. Nos. 4,058. 176 ~ and 4,130,674) or by carrying out an extraction of the oily fraction using an organic solvent immiscible with water, using a flocculating agent to facilitate the separation of solid residues (patent applications Japanese published under N 54.4278 and 54.102305).

Finally, in accordance with an inexpensive process and giving good results, the used oil can be agitated with quaternary ammonium compounds under certain conditions and then subjected to decantation (French patent N08O.09586 of the applicant, published under N0 2,481 .313)
It has now been found that, while retaining the conductive idea of agitation, before decantation, with one or more organic compounds which may have a surfactant power, it was still possible to significantly reduce the contact times with the residual oil as well as the settling time, before recovery of the regenerated oily fraction.

 According to the improved process of the invention, the blackish used oil is subjected to stirring on the one hand with a strong mineral acid and on the other hand with a mixture of an organic compound with a benzene nucleus and a product with alcohol or alcohol ether function, after which the oil is recovered in known manner by decantation in the form of the supernatant fraction.

 The strong mineral acid is used in pure or concentrated form, in amounts generally variable between 1 and 5% of the total volume of residual oil to be treated, depending on the origin and the degree of wear thereof. Preferably, the stirring of the oil with the acid is carried out before the addition of the second ingredient or mixture mentioned above; this for only a few minutes.

 As a compound with a benzene nucleus, it is possible to use either quaternary ammonium salts or halides of aryl type (as in the aforementioned French patent N080.09586) or any other product of surfactant nature, of ionic or nonionic type, comprising at at least one phenyl group in its molecule such as for example a sodium alkylarylsulfonate.

 It has been found, according to the invention, that the addition to the aforementioned aromatic compound of a product containing at least one alcohol or ether function # riVe, generally provides a synergistic effect, during the stirring of the oil, for facilitate the settling of the material to be treated. Various alcohols or polyols can be used for this purpose, for example polyalkyleneglycols or ethers derived from these glycols.

 According to an interesting variant, the organic compound with a benzene nucleus itself is constituted by an alcohol and / or aromatic ether, so that the subsequent addition of alcohol-functional product is avoided, while obtaining excellent results. in the rapid decantation and recovery of the oily function. Among the alcoholic products which can be used, mention may advantageously be made of aromatic alcohols such as benzyl alcohol, phenols and phenolic ethers, alkaylphenoxyalkoxyalkanols or alternatively salts of some of these alcohol ethers. Such hydroxyl compounds or derivatives may themselves be surfactants. ionic or nonionic; otherwise, such a dispersing agent can be added during mixing.

 In practice, in carrying out the process of the invention, the spent oil is stirred for a few moments - for example 1 to 3 minutes - with strong mineral acid, then the aromatic compound and / are poured onto the mixture. or the alcoholic product by diluting the latter with water; the stirring is resumed for a few minutes and then allowed to settle. The operation is facilitated and accelerated when the mixture of oil and treatment product (s) is heated to around 50 to 600C or, better still in some cases, when it is brought to the boil. a very short time, varying from a few minutes to half an hour or more, but which can also be almost instantaneous, gives rise to the formation of three very distinct phases, an upper phase consisting of the regenerated oil which is recovered, a greyish or blackish intermediate phase comprising sedimentary materials and the lower phase consisting essentially of water.

 The invention is illustrated below by the description of some non-limiting embodiments.

Example 1
Was poured slowly, with stirring, 15 ml of pure H2SO4 in 500 ml of a used engine oil type SAE 40 having three months of use at the French National Company of Railways (SNCF); the oil was brown in color with sediment deposition. Stirring was continued for 2 minutes.

dans 200 à 250 ml d'eau ordinaire et introduit sous agitation cette solution dans le milieu acide précité. Après maintien de l'agitation, en fin d'addition, pendant encore 2 à 3 minutes environ, on a transvase dans un récipient approprié et laissé décanter.Then an aqueous solution of 6 ml of octyl phenoxyl polyethoxyethanol was prepared, of global formula

in 200 to 250 ml of ordinary water and introduced, with stirring, this solution into the above-mentioned acid medium. After stirring is continued, at the end of the addition, for a further 2 to 3 minutes approximately, the mixture is transferred to an appropriate container and allowed to settle.

 Series of tests at various temperatures were undertaken and showed that, in all cases, the separation into three phases was clear and that a good quality oil - - could be recovered in the upper phase. However, by heating the mixture to a temperature of 60-700C or by bringing to the boil for one to two minutes, a much faster decantation was obtained.

Example 2
The operation was carried out in the same way as in Example 1, working on 500 ml of a mixture of used motor oil from black motor vehicles with sediments and using on the one hand 15 ml of pure Hcl. and on the other hand 25 ml diluted in 250 ml of water, of a glycolic ether of phenol of the type: nonyl #> hénol polyglycoléthersulfate, of general formula

with R = CH3- (CH2) 8
Good results have also been obtained both for settling and for the quality of the oil recovered in the supernatant phase.

Example 3
The same operations were carried out as in Example 1, treating 500 ml of the same type of used oil with 15 ml of pure sulfuric acid and a mixture of 20 g of sodium arylalkylsulfonate and 6 g of polyethylene glycol, diluted in 250 ml of plain water.

 Decantation in three phases was rapid but facilitated by bringing the mixture, stirred, to the boil for a few minutes.

Example 4
Very similar results to those of Example 3 were obtained by substituting the sodium sulfonate with alkylbenzene sulfonic acid. By cons using the latter acid alone (without addition of alcoholic product), the settling was less
good.

Example 5
Series of tests carried out under the same conditions as in Example 3 but replacing the arylsulfonated surfactant with quaternary ammonium salts such as, for example, alkyl dimethylbenzylammonium chloride (type HYAMINE 3500, registered trademark of
Rohm & Haas) also gave good performance in settling and obtaining a regenerated engine oil.

Example 6
The operation was carried out under exactly the same conditions and with the same products as in Example 1 except that an anionic surfactant constituted by sodium dioctylsulfosuccinate was added to the aqueous addition solution in average amounts of 6 ml.

 It was found that the results were appreciably improved in decantation speed, for an equal temperature and stirring.

Example 7
Tests undertaken on the same oil as in Example 1, still with 15 ml of pure sulfuric acid, but using another aromatic alcohol such as simply benzyl alcohol, gave good decantation but this last one was very slow.

 It could be accelerated by the addition of a surfactant such as that used for example 6.

 The process described above can be implemented advantageously for very diverse categories of used oils, of course non-food to avoid any harmful effect of the treatment agents.

Among these oils, there may be mentioned in particular: oils for draining engines, gearboxes and / or bridges of motor cars and trucks; lubricating oils for machine tools and various mechanisms; transformer oils and other electrical or electropneumatic devices; hydraulic oils and liquids including those of synthesis. .etc.

Claims (6)

- CLAIMS  1. A method of treating used lubricating and industrial oils to obtain a major fraction of regenerated oil which can be used directly, the method being characterized in that the blackish used oil is subjected to stirring in the presence of on the one hand a strong mineral acid and on the other hand a mixture of an organic compound with a benzene nucleus and a product with alcohol or alcoholic ether function, after which the oil is recovered by decantation under form of the supernatant fraction.  2. Method according to claim 1, characterized in that the strong mineral acid, of the HCl group and H2SO4, is used in pure form in an amount between 1 and 5% of the volume of used oil.  3. Method according to any one of claims 1 and 2, characterized in that the organic compound with benzene nucleus is chosen from the group of quaternary ammonium halides with benzene nucleus and surfactants, ionic or nonionic, containing said core, the alcohol-functional product being a mono or polyalcohol  or a derivative ether.  4. Method according to claim 1, characterized in that the organic compound with benzene nucleus and the alcoholic or alcoholic ether product consist of a single compound of the alcohol or aromatic ether type.  5. Method according to claim 4, characterized in that said only compound is a surfactant of ionic or nonionic nature.  6 Method according to any one of claims 1 to 5, characterized in that the mixing with stirring is carried out by heating up to and including the boiling temperature.