EA032029B1 - Spent motor oil recovery method - Google Patents

Abstract

The invention relates to the regeneration of used motor oils and can be used in the technology of cleaning of used lubricants (engine, transmission, industrial, turbine) oils. The objective of the invention is to develop an effective short-term method for the regeneration of used motor oils with bringing their quality indicators to the primary level. The task is achieved by the proposed method of regeneration of used motor oils, including the processing of raw materials with chloric acid at its concentration in an aqueous solution of 10-30 wt.% And the volume ratio of acid to raw materials as (0.6-1.8): 10, followed by neutralization with alkali. As can be seen from the presented examples, the proposed method differs by using the optimal amount and concentration of an aqueous solution of chloric acid, which allows the regeneration process of the used motor oil to be carried out and a purified petrochemical product is obtained with indicators close to the original.

Description

The invention relates to the regeneration of used engine oils and can be used in the technology for cleaning used lubricant (engine, transmission, industrial, turbine) oils.

Lubricating oils lose their original properties during operation. This is due to the accumulation of oxidation products in the composition of waste oils, mechanical impurities, water, resinous compounds, fuels, etc. [12]. The appearance of these components leads to a decrease in the quality of lubricating oils, they cease to fulfill the required functions, which entails the need to replace them with fresh ones.

Despite the fact that in the middle of the 20th century, fundamental research was carried out on the possibility of cleaning used lubricating oils, in the future many of them were recognized as technologically and economically unacceptable, therefore, intensive work in this direction continues. The lack of a unified approach to the problem of cleaning used lubricating oils leads to the use of uncivilized methods for their disposal, in particular, by burning or discharging into sewage systems and water bodies. Therefore, the development of an environmentally friendly method for the regeneration of used motor oils is aimed both at the conservation of hydrocarbons and the protection of the natural environment.

A variety of technologies for cleaning waste lubricating oils are based on the use of physical, physicochemical and chemical methods [1-3]. The most common among them are acid and alkaline cleaning, the use of reagents, the use of centrifugation, magnetic separation, filtration, vacuum distillation, and adsorption technologies. Common disadvantages of known technologies are the use of aggressive reagents, multi-stage, energy consumption and the complexity of disposal of the resulting chemically aggressive sludge [3].

A known method of regeneration of waste oils by purification using sulfuric acid, which is introduced at a ratio of sulfuric acid: water from 1: 0.2 to 1: 1.5, followed by separation of the reaction mixture in the sump into acid, tar and oil phases and a separate selection of phases. In this case, if necessary, the acid and resin phases during sedimentation are mixed and / or heated to 40-100 ° C [4].

The disadvantages of this method are the use of concentrated sulfuric acid, which leads to the resinization of not only pollution, but also the hydrocarbon base of the oil, the difficulty of separating the resulting stable emulsion, large losses of feedstock (up to 50%), as well as the formation of a significant amount of difficult to utilize and environmentally hazardous product - acid tar.

A known method of purification of waste oils, which consists in processing pre-cleaned of mechanical impurities by magnetic separation, centrifugation and filtering the oil at a temperature of 15-80 ° C with an aqueous solution of the reagent with a ratio of reagent and water 1: 1 and settling to full transparency. The reagent used contains, wt.%: Phosphoric acid - 60-95, isopropyl alcohol - 4.7-39.7 and methyl ethyl ketone - 0.3-10 [5].

The disadvantages of this method are multi-stage, the complexity of the hardware design, as well as the composition of the solvent, including low-boiling alcohol and ketone, which increases the fire hazard of the process.

A known method of purification of waste oils, which consists in processing waste oil with dilute hydrochloric or sulfuric acids at a concentration of 2-40 wt.%, The volume ratio of acid: oil is 1: 1-1: 15, the duration of the contact phases 5-30 minutes, without heating [6] (prototype).

The disadvantages of this method are the duration of the phase separation stage. So, in the case of using hydrochloric acid to achieve a degree of purification of the test oil> 90% according to the photocolorimetric analysis, the duration of the phase separation stage will be 15-240 hours.

The objective of the invention is to develop an effective short-time method for the regeneration of used motor oils with bringing their quality indicators to the primary level.

The task is achieved by the proposed method for the regeneration of used motor oils, including processing the feed with chloric acid at a concentration of 1030 wt.% In an aqueous solution and a volume ratio of acid to feed as (0.6-1.8): 10, followed by neutralization with alkali.

The novelty of the proposed method is the use of perchloric acid, a 10-30% aqueous solution of which is introduced at a volume ratio of acid to raw material as (0.6-1.8): 10.

The observed effect was achieved due to the ease of interaction of the chloric acid used, which is one of the strongest oxidizing agents, and the components that make up engine oil additives (such as alkali and alkaline earth metals, phenol sulfide-containing groups, etc. [8, 9]). The occurring break in chemical bonds leads to the destruction and loss of functional properties of additives, which entails the ease of deposition of oil contaminants.

The authors did not identify sources of information that provide data on the possibility of regeneration of used motor oils using perchloric acid.

- 1 032029

To solve this problem, chloric acid (GOST 6552-80) was used, and used motor oil was used as a raw material (Table 1).

Table 1

Physico-chemical characteristics of fresh and used engine oil

Indicators Definition Standards Before operation and After operation * Density at 20 ° С, kg / m ³ GOST 3900-85 870 885 Viscosity index GOST 25371-97 151 128 Flash point in open crucible, ° C GOST 4333-2014 225 198 pH at 20 ° C GOST 11362-96 7.83 7.85 Refractive index "20 Lp - 1,467 1,486

^ Duration of operation was 5000 km.

The degree of clarification of the oil was determined by photocolorimetric analysis (GOST 24943-81).

The proposed method is as follows: in a used engine oil with constant stirring, a 10-30% aqueous solution of perchloric acid is introduced. Stirring is carried out for 10-30 minutes, after which the mixture is left to stand for 1-10 hours until it is separated into two layers: a clear oil and a tarry precipitate.

Example 1

Used raw oil, taken in an amount of 50 ml, is introduced into the raw material with constant stirring 3 ml of a 10% aqueous solution of perchloric acid (ratio 0.6: 10). Stirring is carried out for 20 minutes, after which the mixture settles for 5 hours. The settled mixture is divided into two layers: the upper layer is a clarified motor oil of light yellow color and the lower layer is a resinous precipitate of black color. The characteristics of the sample of oil obtained during the regeneration of waste are given in table. 2.

The results obtained in example 1 indicate an increased acidity of the sample, which makes it impossible to use regenerated motor oil for its intended purpose. Therefore, subsequent samples after acid regeneration were subjected to alkali neutralization according to the known technology [7].

Example 2. The method according to example 1, characterized in that the purified oil was further subjected to neutralization with alkali (based on: 10 wt.% 5% aqueous solution of Na ₂ CO ₃ on the treated oil). The characteristics of the sample of oil obtained during the regeneration of waste are given in table. 2.

Example 3. The method according to example 1, characterized in that the purified oil was further neutralized with alkali (based on: 20 wt.% 5% aqueous solution of Na ₂ CO ₃ on the treated oil). The characteristics of the sample of oil obtained during the regeneration of waste are given in table. 2.

Example 4. The method according to example 1, characterized in that the purified oil was further subjected to neutralization with alkali (based on: 30 wt.% 5% aqueous solution of Na ₂ CO ₃ on the treated oil). The characteristics of the sample of oil obtained during the regeneration of waste are given in table. 2.

Example 5. The method according to example 1, characterized in that the purified oil was further subjected to neutralization with alkali (based on: 10 wt.% 10% aqueous solution of Na ₂ CO ₃ on the treated oil). The characteristics of the sample of oil obtained during the regeneration of waste are given in table. 2.

The results obtained during the experiments indicate that the use of 10-20 wt.% 5% aqueous solution of Na ₂ CO ₃ on the treated oil is sufficient to achieve the required pH level (examples 2 and 3). An increase in the amount and concentration of alkali over this limit (examples 4 and 5) leads to an increased consumption of reagents against the background of a deterioration in the characteristics of the regenerated oil.

Example 6. The method according to example 2, characterized in that 6 ml of a 10% aqueous solution of perchloric acid are introduced into the used engine oil (1.2: 10 ratio). The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

Example 7. The method according to example 2, characterized in that 9 ml of a 10% aqueous solution of perchloric acid (1.8: 10 ratio) is added to the used engine oil. The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

Example 8. The method according to example 6, characterized in that the waste engine oil is injected with a 20% aqueous solution of perchloric acid. The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

Example 9. The method according to example 6, characterized in that a 30% aqueous solution of perchloric acid is introduced into the used engine oil. The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

- 2 032029

The data given in table. 2, indicate that an increase in the concentration and quantity of an aqueous solution of perchloric acid appears to be impractical, due to an unjustified increase in reagent consumption against the background of a decrease in the qualitative characteristics of the target product: an increase in the viscosity and acid number of motor oil (examples 7 and 9).

Example 10. The method according to example 8, characterized in that after adding acid to the used oil, stirring is carried out for 10 minutes The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

Example 11. The method according to example 8, characterized in that after adding acid to the used oil, stirring is carried out for 30 minutes The sequence of further operations as in example 1. The characteristics of the sample of oil obtained during the regeneration of waste, are given in table. 2.

table 2

Used engine oil cleaning results

Indicators Prototype Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 . .......... Example 11 Example 12 Example 13 | Physico-chemical properties of oil samples Density at 20 ° С, kg / m ³ * 850 - - - - 857 863 870 878 870 870 870 870 Viscosity index * 124 - - - - 132 141 150 147 148 147 147 147 Flash point in open crucible, ° C 210 - - - - 212 218 220 220 217 217 217 218 pH at 20 ° C * 4.35 7.82 7.86 7.96 7.89 7.85 7.84 7.80 7.20 7.80 7.80 7.80 7.26 Refractive Index, p ™ * 1,480 - - - - 1,475 1,470 1,467 1,467 1,475 1,471 1,476 1,478 | Cleaning Process Parameters Mixing time, min 20 20 - - - - 20 20 20 20 10 thirty 20 20 Duration of sludge, hour 18 5 - - - - 5 5 5 5 5 5 1 1 The yield of purified oil,% wt. ** 67 - - - - 75 76 80 82 74 80 64 65 The degree of oil purification according to FEC,% 93.9 64.9 - - - - 67.8 68.0 96 95.1 84 91 79 76

* In the prototype there is no data on the physico-chemical properties of the regenerated oil.

** In the prototype there is no data on the yield of purified oil,% wt.

The marked decrease in the yield and degree of purification of the obtained oil is the result of an insufficiently long contact of the oil and acid (example 10), or when the optimal value of this indicator is exceeded (example 11) - to an increase in the duration of phase separation and, as a consequence, to a decrease in the yield of the target product.

Example 12. The method according to example 8, characterized in that after adding acid to the used oil and mixing, the mixture settles for 1 hour. The sequence of further operations as in example 1. The characteristics of the oil sample obtained during the regeneration of the used are shown in table. 2.

Example 13. The method according to example 9, characterized in that after adding the acid to the used oil and mixing, the mixture settles for 1 hour. The sequence of further operations as in example 1. The characteristics of the oil sample obtained during the regeneration of the used are shown in table. 2.

The results obtained (see table. 2, examples 12 and 13) indicate that the completeness of the deposition of particles distributed in the oil volume depends on the duration of the sludge. An increase in the duration of more than 5 hours is impractical due to the achievement of the required degree of purification of used oil. An increase in acid concentration leads to a decrease in the degree of purification due to a decrease in the rate of deposition of suspended particles in a solution with a higher density.

As can be seen from the presented examples, the proposed method is characterized by the use of the optimal amount and concentration of an aqueous solution of perchloric acid, which allows for the process of regeneration of used engine oil and to obtain a refined petrochemical product with indicators close to the initial ones.

Claims (1)

The method of regeneration of used engine oil, including treatment with mineral acid, characterized in that the treatment of used engine oil is carried out with perchloric acid at a concentration of 10-30 wt.% In an aqueous solution and a volume ratio of acid to oil (0.6-1.8): 10 followed by neutralization of the regenerated oil with alkali.