A COMPOSITION AND METHOD FOR UTILIZING THE SLUDGE OBTAINED WHEN PROCESSING WASTE LUBRICATING OILS

Abstract: This invention concerns a method whereby the sludge obtained when reclaiming waste lubricating oils by treating with acids or solvents can be processed by the addition of elastomers and hardeners to obtain a compound which - when used in conjunction with bituminous conglomerates and mixtures - gives these conglomerates or mixtures superior mechanical characteristics and high strength, at high and low temperatures.

Description: Waste lubricating oils contain asphaltum-type impurities and cracked-oil residues chat have to be removed when reclaiming the oils for reuse. During this reclaiming process, a considerable amount of sludge is produced which is normally discarded. Finding a way to make commercial use of this sludge and, at the same time, reap benefits front the point of view of the protection of the environment, has represented a very interesting problem. Both today as in the past, great amounts of this sludge accumulate at waste-oil reclaiming plants and in other more-or-less makeshift storage areas, giving off offensive odors, threatening to pollute water sources and otherwise adversely affecting the environment and nearby communities. Selective solvents, such as propane, have been recently used in the waste-oil reclaiming process. It is therefore the specific problem and task of the present invention to find a beneficial use for those sludges resulting from waste-oil reclamation or reprocessing which will be sound both economically and ecologically and provide a safe final disposal of those sludges. To this purpose, in accordance with the basic idea of the present invention, there is provided a composition useful in road surfacing, waterproofing of materials, sealing of dams and other applications when said composition is mixed with bitumen, said composition comprising a sludge obtained from waste-lubricating-oil reclamation, an elastomer component selected from the group consisting of EPDM and SBS copoymers, and a hardening product consisting of isotactic polypropylene. There are several types of reclamation processes known in the art, and sludges obtained from these various known reclamation processes may be used for the purposes of the present invention. More particularly, in accordance with an advantageous embodiment of the invention said sludge component used in said composition of the present invention may consist of sludges from waste-lubricating-oil reclamation by means of selective solvents. In accordance with an alternative embodiment said sludge component of the composition of the present invention inay consist of sludges obtained from waste-lubricating-oil reclamation by means of a sulfuric acid treatment followed by neutralization. The invention also relates to methods for preparing the composition and bituminous conglomerates utilizing the ternary composition of the present invention as a constituent additive to bituminous mixtures. Such methods are defined in claims 5-12. In connection with improving the general characteristics of bitumen compositions, French specification 2 228 817 (SIPLAST) discloses the use of EPDM copolymers as an 'elastomer' additive and of (isotactic or atactic) polypropylene as a solvent component. In this known procedure, the polypropylene component is proposed as a solvent component to facilitate the use of EPDM as an elastomer additive, in replacement of former polymer additives which had been limited to polymers of low viscosity and hence of low molecular weight and/or low ramification type polymers. French specification 2 288 127 (Shell) discloses the addition of used lubricating oil as such, which is considered to be a waste product, to bitumen, whereby to obtain a bituminous product with advantageous properties and qualities for particular purposes. The reference exclusively contemplates addition of the used-up lubricating oils as such, and maintains that waste-oil reprocessing is not a feasible process. Instead, by means of the present invention, the sludge refuse of waste-oil reclaiming processes can be turned into a useful product. This is best accomplished by starting out with the aforementioned type of sludge obtained when solvents are used in the waste-oil reclaiming process. This type of sludge is doughy and contains asphaltum substances and cracked-oil carbonaceous fractions, as well as lubricating-oil fractions, polymer-additive fractions and metallic fractions. The very small amount of inorganic material contained in the sludge has about 18-25 % ash content and a P. & A. softening point of about 104-105° C. It was discovered that this type of sludge is compatible with elastomers and hardeners, and that at the appropriate temperature they can be easily mixed together to form a high-quality product for use as an additive for bitumens. The S.B.S. type elasticizer can be used, for example, but E.P.D.M. copolymers are preferred because of their resistance to atmospheric agents, low and high temperatures and light. Isotactic polypropylene was selected as the hardener because of its low cost, excellent compatibility and high efficiency. The most optimum formula for preparing a specific binding compound for bituminous conglomerates used in surface pavings in general, including road surfaces, is given below. This "optimal compound" - whose very special characteristics as a binder, also in other applications, are described further on -is obtained by hot mixing the sludge "as is" with the other components, in the following proportions: Sludge "as is" 66 % Copolymer terpolymer - ethylene propylene (elastomer) 17% Isotactic polypropylene 17% The mixture is mechanically mixed (at ca. 200-250 rpm) and heated to 180-190°C. Powdered ethylene/propylene copolymer (600-800 µm) is first added and stirred in until the mixture is homogeneous. Then powdered isotactic polypropylene (600-800 µm) is added and stirred in until the compound is homogeneous. The resulting product is quite doughy, has good elasticity and a very high P.& A. softening point (183-185° C). The most important applications of this "optimal compound" are as follows: A) Road Surfacing The best method for this application, since the compound is in the solid state and considering the particular operational procedures involved, is to first mix 20; 25, 30 or 40% of the "optimal compound" (according to the particular job requirement)with distilled bitumen of the type 180-200 and then prepare small "loaves" of this mixture. Prepared in this manner the ready-to-use "loaves" can be mixed with (and melted by) the hot aggregate (160-180° C), such as sand, stone and various fillers, which is fed into the conglomerate mixing unit. With a proportion of 6% binder and 94% inert material, the conglomerate will contain the desired solid amount of the aforesaid "optimal compound". The preferred amount of "optimal compound" to add to the distilled bitumen of the type 180-200, when preparing the aforesaid "loaves" is 25% The addition of "loaves" having this composition to the conglomerate will provide a resistance to temperatures ranging from - 25° C to + 150° C. B) Waterproofing of Cardboard, Felt, etc. It was observed that the plasticizers, elastomers and hardeners used in the preparation of bituminous mixtures for waterproofing cardboard, felt, joints and sleeves, can all be replaced by the aforesaid "optimal compound". This product by itself, therefore, does the job of all three of the components that are normally added to the required bituminous mixture, which represents savings of both cost and time. The amount of "optimum compound" added to the distilled bitumen of the types 180-200 or 80-100 can vary between 20 and 40% C) Substitution of Atactic Polypropylene (PRA) The aforesaid "optimal compound" can advantageously substitute PRA in the preparation of sealers for dams or similar applications. The reason for this is that it is the only product that melts easily at 180-190° C while being mechanically agitated. The results of the tests carried out on samples of bituminous conglomerate used for road surfacing, as described in the foregoing section "A", are given below by way of proof of the validity and novelty of this invention. The four parameters generally used for the evaluation of products of this type are shown, with the first column showing the results obtained in the tests and the second column showing the values for the products that have been normally used to date. Measured Parameter Test Samples Standard Values Penetration Index + 5 - 0.8 to - 0.9 Marshall Stability ca. 1500 kg ca. 950 - 960 kg Marshall Slip ca. 3.85 mm ca. 3.60 - 3.65 mm Marshall Rigidity ca. 330 ca. 264 The obtained penetration index of + 5, which indicates the susceptibility of a bitumen to temperature, is exceptionally high and is of particular interest as regards the product concerning this invention. There are great quantities of sludges now on the market that have been obtained from the old method of waste-oil reclaiming, where the waste oil is first subjected to a sulfuric acid treatment and then neutralized using lime. In contrast to the sludges obtained using solvents, these sludges have a high inorganic content, which does not make them very suitable for making waterproofing compounds for cardboard, felt and the like, or for making sealing compounds for dams and similar applications. On the other hand, as regards the road-surfacing application this high inorganic content of the acidified and neutralized sludges makes them more suitable because the inert material contributes to the aggregates normally added to the conglomerate. The disadvantage of these abundantly available acidized and neutralized sludges is that they cannot be used for road surfacing in countries that are either very warm or very cold, because at these extreme temperatures maximum strengths cannot be obtained. Another disadvantage of these sludges regards the use of the compound. The high inorganic content inhibits the making of the ready-made "loaves" for use on the site together with the hot aggregates for making the conglomerate. Consequently another "optimal compound" - similar to the one obtained with the sludge treated with solvents - has to be made. Since the inorganic content of this "optimal compound" is high - which does not permit making the aforesaid "loaves" by melting the said compound into the type 180-200 distilled bitumen - it has to be powdered to a grain size measuring less than 1000 Nm (usually about 500-800 µm). In this powdered form, the "optimal compound" is ready for being mixed together with melted bitumen at high temperature, of the type 180-200, which is added to the aggregate. The amount of binder is still about 6%.

Claims: A composition useful in road surfacing, waterproofing of materials, sealing of dams and other applications, when said composition is mixed with bitumen, said composition comprising a sludge obtained from waste-lubricating-oil reclamation, an elastomer component selected from the group consisting of EPDM and SBS copolymers, and a hardening product component consisting of isotactic polypropylene. The composition of claim 1, wherein said sludge component consists of sludges from waste lubricating oil reclamation either by means of selective solvents, or by means of sulphuric acid treatment followed by neutralisation. The composition of claim 1, wherein said composition contains 66 % of the sludge component obtained from waste lubricating oil reclamation by means of selective solvents, 17 % of EPDM elastomer, and 17 % of isotactic polypropylene hardener. A bitumineous binder composition containing 20-40 % of the composition of claim 3, the remainder distilled bitumen. Method of preparing the composition of claim 3 by mechanically mixing the components at 180-190°C. Method for preparing bituminous conglomerates, utilizing the composition of claims 1 or 2, said method comprising mechanically mixing said sludge component obtained from waste-lubricating-oil reclamation by means of selective solvents, heating, adding in a powdered form said elastomer component selected from the group consisting of EPDM and SBS copolymers, stirring to provide a homogeneous mixture, adding to said mixture in a powdered form said isotactic polypropylene hardening component, stirring to provide a homogeneous mixture, shaping said mixture into small slabs, melting said slabs and mixing together with distilled 180 - 200 type bitumen in a proportion of 20 to 40 % mixture, the remainder bitumen, thereby forming a final mixture and shaping said final mixture into loaves. Method for preparing bituminous conglomerates utilizing the composition of claims 1 or 2, said method comprising mechanically mixing said sludge component obtained from waste-lubricating-oil reclamation by means of a sulfuric acid treatment followed by neutralization, heating said sludge, adding in a powdered form said elastomer component selected from the group consisting of EPDM and SBS copolymers, stirring to provide a homogeneous mixture, adding to said mixture in a powdered form said isotactic polypropylene hardening component, stirring to provide a homogeneous mixture, powdering said mixture to a grain size less than 1000 microns, and mixing together with melted distilled 180 - 200 type bitumen. The method according to claim 6, further comprising mixing 6 % of the conglomerate with 94 % of aggregate. Use of the composition of claim 4 in road surfacing, comprising mixing and melting said composition with a hot road surfacing aggregate of a temperature from 160° - 180°C in a proportion of 6 % composition to 94 % aggregate and feeding the mixture into a conglomerate mixing unit. The method according to claim 7, for employment in road surfacing, further comprising mixing said bituminous conglomerate with a hot road surfacing aggregate in a proportion of 6 % conglomerate to 94 % aggregate, and feeding the mixture into a conglomerate mixing unit. The method according to claims 9 or 10, wherein said road surfacing aggregate comprises sand, stone and fillers. The method according to claim 5, wherein said elastomer component and said hardening component polyppropylenes are powdered to 600-800 µ.

Inventors: FACHINI, MARCO, DR.
Applicants: FACHINI, MARCO, DR.
Application year: 1986
Main classification: C08L95
IPC codes: E01C7, C08L95, C08L7, C08L101, C08L23, C09K3, C08L21, C02F11