CLOSED-CIRCUIT MOBILE SYSTEM FOR RECOVERING CONTAMINATED SOILS AND PROCESS FOR RECOVERING CONTAMINATED SOILS

Abstract

The present abstract relates to an invention patent for a closed-circuit mobile system for recovering contaminated soils, pertaining to the field of combating environmental pollution; said system comprising, essentially: 1)a step of washing the contaminated soil SC (block 1), consisting essentially of removing the contaminated soil SC from the place of origin O and homogenizing same under high pressure with washing solution SLAV comprised of water+washing product PL containing modified terpenoids and/or terpenes; provided by compact washing equipment (1) installed close to the place of origin O of the contaminated soil SC where the recovered soil SR is backfilled; and 2)a recovery step carried out using centrifugal clarifier (10) and centrifuge (20) (block 2), wherein recovered contaminants CR and recovered washing product PLR are produced, the latter being recycled to make up washing solution SLAV, and the recovered contaminants CR being reused in process P that originated same or other; said steps (1) and (2), process P which originated the contaminated soil SC, the means for providing washing solution SLAV, and the outlets for recovered soil SR from step (1) and for recovered contaminants CR and recovered washing product PLR from step (2) forming a closed circuit, which does not substantially produce disposable material(s).

Claims

1-14. (canceled)

15. Closed-circuit mobile system for recovery of contaminated soils comprising: (a) a storage means (2) that receives the contaminated soil SC and is circulated on a conveyor (5) towards the washing subassembly; (b) a washing subassembly (3) comprising: b.1a feed means (7) containing a washing product and water (SLAV); b.2at least one sprayer (6) receiving the washing solution SLAV from the feed means SLAV (7), wherein spraying occurs at high pressures of said SLAV at the contaminated soil SC from the conveyor 5 described in step (a); b.3a rinsing subassembly (4) on a conveyor (5) comprising at least one sprayer (6) receiving the washing solution SLAV from the SLAV feed means (7), wherein spraying occurs at low pressures of said SLAV at the contaminated soil SC from the conveyor (5) as described in step (a); and(c) a recovery subassembly (2) comprising:c.1at least one vibrating screen (8) separating the emulsion formed by water+SLAV+contaminants C from recovered soil SR, wherein the SR is sent (9) to the process of origin (P/O); c.2a centrifugal clarifier (10) containing an outlet for solids washed SL and another outlet for the washing solution, contaminants and suspended solids (S); and c.3a centrifuge (20) for recovering the recovered contaminant CR and the recovered washing solution (SLAVR) wherein CR is sent to a storage tank (21) and SLAVR is recirculated to the feed tank SLAV (7), wherein the washing solution SLAV of step b.1 comprises a solution of modified terpenes and/or terpenoids and water.

16. Closed-circuit mobile system for recovering soils according to claim 15, wherein the contaminated soil S/C has the following contaminants: mineral oils, hydrocarbons, petroleum, or mixtures thereof.

17. Closed-circuit mobile system for recovering soils according to claim 15, wherein the solution of modified terpenes and/or terpenoids is from d-limonene oxidation, selected from: d-limonene, d-carveol, l-carveol carvone, limonene oxide, limonene epoxide, phellandrene, terpendiol, terpineol, dihydroxy-carvone, or mixtures thereof.

18. Closed-circuit mobile system for recovering soils according to claim 15, wherein the washing product SLAV additionally comprises nonionic surfactants of food grade having 1 to 20 carbon atoms in its chain.

19. Closed-circuit mobile system according to claim 15, wherein at least one sprayer of step b.2 operates at a pressure of 3000 to 20000 KPa.

20. Closed-circuit mobile system according to claim 15, wherein at least one sprayer of step b.3 operates at a pressure of 200 to 1000 KPa.

21. Closed-circuit mobile system according to claim 15, wherein the centrifuge (20) additionally comprises a third PI stream for intermittent purging.

22. Closed-circuit mobile system for recovering soils according to claim 15, wherein the flow rate of the washing solution in step (b) comprises from about 10 to 20 m3/h for capacity of up to 10 tons/hour of contaminated soil at a pressure between 30 and 200 bar.

23. Closed-circuit mobile system for recovering soils according to claim 15, wherein the flow rate of the washing solution in step (b) comprises from about 10 to 20 m3/h for capacity of up to 10 tons/hour of contaminated soil at a pressure between 10 and 20 bar.

24. Closed-circuit mobile system for recovering soils according to claim 15, wherein the centrifugal clarifier (10) has two outlet streams, wherein the first outlet consists of washed solids SL with moisture content between 11% and 20% which is joined to the recovered soil SR and the second outlet corresponds to the SLAV solution, hydrocarbons C and a percentage lower than 2% of suspended solids S that bind to the centrifuge (20).

25. Closed-circuit mobile system for recovering soils according to claim 15, wherein the centrifuge (20) has three stages and is vertically mounted performing centrifugation in which the contaminants C are recovered and sent to a storage tank (21) for reuse and wherein the recovered washing solution SLAVR is sent to the tank (7) for later reuse, further comprising a third stream (intermittent purging) that occurs at a specific outlet whereto the solids are sent and can be added to the washed soil SL in the washing process.

26. Closed-circuit mobile system for recovering soils according to claim 15, wherein the equipment composing the system is a compact unit comprised of: a washing subassembly (3) comprising at least one sprayer (6) and a recovery subassembly including at least one vibrating screen (8), a centrifugal clarifier (10) and a centrifuge (20).

27. A process for recovering contaminated soils, comprising the following steps: 1. removing contaminated soil SC from the place of origin O and placing it in a storage means (2) so that said SC is fed into conveyors (5); 2. spraying the washing solution SLAV through a washing subassembly (3) and promoting homogenization of the contaminated soil SC with the washing solution SLAV; and 3. subjecting the contaminated soil to homogenization with the washing solution in a recovery subassembly, comprising at least one vibrating screen (8), a centrifugal clarifier (10) and a centrifuge (20) for recovery of the following materials: (i) recovered soil SR, (ii) recovered washing solution SLAVR and (iii) recovered contaminant CR.

28. A process for recovering contaminated soils according to claim 27, further comprising the following sub-steps: i. removing the contaminated soil SC from the place of origin O and placing it in a storage means (2) so that said SC is fed into conveyors (5); ii. subjecting a water-based washing solution (SLAV) and a washing product based on modified terpene and/or terpenoids to a pressure of 3000-20000 KPa in the contaminated soil (SC); iii. checking emulsion formation consisting of washing solution SLAV and contaminants mixed with the soil particles; iv. subjecting the emulsion obtained in step iii above to a final rinse in a conveyor to a pressure of 20 to 1000 kPa for fine removal of residual contaminants; v. promoting the resultant solution on a recovery subassembly, comprising at least one vibrating screen (8), a centrifugal clarifier (10) and a centrifuge (20) for recovery of the recovered soil SR, of the recovered washing solution SLAVR and of the recovered contaminant CR; and vi. storing the washed soil SL for later return to the place of origin O.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0061] FIG. 1is a detailed representation of the closed-circuit washing process (1) wherein the contaminated soil (SC) is stored in a suitable location (2), then is poured on a mobile conveyor (5) wherein the washing solution (SLAV) stored in (7) is added by means of high pressure jet (6) completing the washing step (3); in the recovery step (4) the contaminated soil and the washing solution pass through the rinsing process (8) which comprises three screens (8a), the larger particles of the soil already recovered (SR) are transferred and can be backfilled (9) while the finest part passes through the clarification process (10) wherein part of the soil is again recovered and the remaining passes through a centrifuge (20) wherein the recovered contaminant is stored for further use (21), the recovered washing solution (SLAVR) is separated and reused, and a third intermittent purging stream (PI) occurs at a specific outlet whereto the solids are sent and can be added to washed soil SL in the washing process.

[0062] FIG. 2is a simplified representation of the mobile system installed within a truck where the contaminated soil (CS) is sent and stored in an appropriate location (2) after receiving the washing solution via pressurized jets (6) completing the washing step (3); in the recovery step (4) the contaminated soil and the washing solution pass through the rinsing process (8) wherein the fine part of the soil passes through the clarification process (10) and what has not been separated from the contaminants passes through the centrifugation process (20), the washing solution with contaminants is then transferred to separating tank wherein the washing solution is then stored (7) for reuse in the process and the recovered contaminants are stored in the appropriate place for further use.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0063] As illustrated by the abovementioned figures and described in the present invention, the system object of the present application is intended to recover soil contaminated with mineral oils, hydrocarbons (petroleum) and the like and is comprised essentially of two steps (FIG. 1):

[0064] 1)Step of washing the contaminated soil SC (1) consisting essentially of removing the contaminated soil SC from the place of origin O and homogenizing it under high pressure with washing solution SLAV composed of water+washing product PL based on modified terpenes and/or terpenoids which active is obtained according to patent application PI 0903082-4 of the same applicant, washing product PL which is also the subject of another patent application of the same applicant;

[0065] 2)Step of recovery (4) made with centrifugal clarifier 10 and centrifuge 20 of the soil washing unit; said 2)recovery step in which the recovered contaminants CR are obtained and taken from contaminated soil SC and recovered washing product PLR, this being reused to compose the washing solution SLAV used in step 1 of soil washing; and the recovered contaminants CR are reused in process P from which they originate or others;

[0066] Said steps 1 and 2, the process P originator of contaminated soil SC; means for supplying the washing solution SLAV; and the outlets of recovered soil SR from step 1 as well as outlets of recovered contaminants CR and recovered washing product PLR from step 2 composing a closed circuit and not originating disposable material(s).

[0067] The washing product PL based on modified terpenes and/or terpenoids obtained according to patent application PI 0903082-4 is also the subject matter of another patent application of the same applicant and used in the present washing process, being comprised essentially of: mixtures obtained by oxidation of d-limonene; surfactants with emulsifying function; and water as vehicle.

[0068] In one aspect, said mixture of terpenes and/or terpenoids comprises: d-limonene, d-carveol, 1-carveol carvone, limonene oxide, limonene epoxide, phellandrene, terpendiol, terpineol, dihydroxy-carvone, or mixtures thereof.

[0069] In another aspect, said mixture of terpenes and/or terpenoids comprises: limonene, its isomers and/or oxygenated derivatives.

[0070] The surfactants are non-ionic of food grade 20 having 1 to 20 carbon atoms in its chain, and preferably, but not limited to: ethoxylated alcohols, polyol esters or polyethylenes, alkyl polyglucosides, ethoxylated polyol esters and polysorbates.

[0071] The washing product PL with such characteristics enables the completion of the washing process as described above in essence.

[0072] The present invention also relates to a process for recovering contaminated soils, comprising the steps of:

[0073] 1. Removing contaminated soil SC from the place of origin O and placing it in a storage means (2) so that said SC is fed into conveyors (5);

[0074] 2. Spraying the washing solution SLAV by means of a washing subassembly (3) and promoting homogenization of contaminated soil SC with the washing solution SLAV; and 3. Subjecting the contaminated soil to homogenization with the washing solution in a recovery subassembly, comprising at least one vibrating screen (8), a centrifugal clarifier (10) and a centrifuge (20) for recovery of the following materials: (i) recovered soil SR, (ii) recovered washing solution SLAVR and (iii) recovered contaminant CR.

[0075] Particularly, the process for recovering contaminated soils of the present invention consists of the following sub-steps:

[0076] i. Removing contaminated soil SC from the place of origin O and placing it in a storage means (2) so that said SC is fed into conveyors (5);

[0077] ii. Subjecting a water-based washing solution (SLAV) and washing product based on modified terpenes and/or terpenoids to a pressure of 3000 to 20000 KPa in contaminated soil (CS);

[0078] iii. Checking emulsion formation consisting of washing solution SLAV and contaminants mixed with the soil particles;

[0079] iv. Subjecting the emulsion obtained in step iii above to a final rinsing in a conveyor at a pressure of 20 to 1000 KPa for fine removal of residual contaminants;

[0080] v. Promoting the resultant solution on a recovery subassembly, comprising at least one vibrating screen (8), a centrifugal clarifier (10) and a centrifuge (20) for recovering the recovered soil SR, the recovered washing solution SLAVR and the recovered contaminant CR; and

[0081] vi. Storing the washed soil SL for later return to the place of origin O.

[0082] More specifically, the soil recovery system and process of the invention comprise the following steps:

[0083] The step of soil washing comprising mainly the steps of (FIG. 1):

[0084] 1)Removal of contaminated soil from its place of origin;

[0085] 2)Storage of contaminated soil in a suitable location (2) next to the washing machine;

[0086] 3)Washing the soil under high pressure (6) consisting of feeding the contaminated soil into an appropriate washing equipment supplied with washing solution made from water and washing product based on modified terpenes and/or terpenoids (7); said equipment performing:

[0087] 3.1)Homogenization under high pressure between the contaminated soil and the washed product based on modified terpenes and/or terpenoids, which is made by spraying under high pressure of the washing product on the soil until breaking up the agglomeration of the soil particles. Better explaining, so that there is an efficient removal of contaminants, the washing product based on modified terpenes and/or terpenoids needs to be homogenized with these contaminants. As the contaminated soil, especially that with higher clay content, are well packed, there must be a way to promote this contact. The process of the present invention uses a high-pressure equipment that sprays the product on the contaminated soil. This pressure is selected to break up agglomerations of particles and take the washing product to a large surface area. The pressure varies from 3000-20000 KPa.

[0088] 3.2)Formation of emulsion comprising water, washing product based on modified terpenes and/or terpenoids and contaminants, mixed with soil particles. With the application of high pressure washing product (3000-20000 kPa) in the contaminated soil, the washing product emulsifies the contaminants (hydrocarbons) contained in the soil;

[0089] 3.3)Final rinsing in conveyors. The soil already washed is subjected to a final rinsing conveyor wherein the washing product based on modified terpenes and/or terpenoids is again placed in contact with the soil particles for fine removal of residual contaminants. This rinsing is performed in sprayed solution screens at low pressure (200 to 1000 kPa) on the soil already washed displaced in the conveyor.

[0090] 4)Separation of the solution (water+washing product+contaminants) in the soil (8) made on vibrating screens with a negative gradient (0 to 60);

[0091] 5)Storage of the washed soil for later return to the place of origin.

[0092] The effective washing parameters of steps 3.1, 3.2 are in the correct adjustment of the washing solution flow of about 5 to 20 m3/h for capacities of up to 10 tons/hour of contaminated soil; with washing pressure in the range 3000-20000 KPa. The effective final rinsing parameters of step 3.3 consist of the rinsing solution flow at about 10 to 20 m3/h for capacity of up to 10 tons/hour of contaminated soil, rinsing solution pressure of 200-1000 KPa, number of rinsing screens of 1-3 screens.

[0093] Recovery step 2 is comprised of:

[0094] 6)Clarification (10). The solution comprising water, washing product based on modified terpenes or terpenoids, contaminants and the solid suspended material is subjected to clarification to separate the liquid phase from the solid phase, constituted by soil particles that are joined to the stored soil 5.

[0095] 7)Centrifugation (20). A solution composed of the washing product based on modified terpenes or terpenoids+contaminants is centrifuged separating the washing product based on modified terpenes or terpenoids, which is returned (7) to the washing step (3) and the recovered contaminants, which are forwarded once again to the originating process (21) or other destinations.

[0096] The equipment that implements the soil recovery system of the invention is essentially according to the scheme shown in FIG. 2.

[0097] The equipment is a compact unit composed of: washing equipment that performs step 3 of soil washing; and a centrifugal clarifier 10 and centrifuge 20 that perform step 4 of recovery.

[0098] The washing equipment consists essentially of: A storage means (2) receiving the contaminated soil SC (hopper);

[0099] Washing subassembly 3, receiving the contaminated soil SC from hopper (2);

[0100] Final rinsing subassembly (8) that receives the washed soil SL from the washing subassembly 3; said subassemblies 3, 4 basically comprised of respective soil transporters; sprayers 6 spraying high pressure washing solution SLAV (water+PL washing product based on modified terpenes and/or terpenoids) on the contaminated soil SC, which circulates in the conveyor of the washing subassembly 3 and sprays with a lower pressure on the washed soil SL, which circulates in the conveyor of the final rinsing subassembly 8;

[0101] Feed means 7 of the washing solution SLAV (washing product PL+water);

[0102] Vibrating screen 8 that separates the emulsion formed by water, the washing solution SLAV+contaminants C from the recovered soil SR;

[0103] The washing equipment is a compact unit that has its active components mounted in a truck, exhibits little volume and low weight of about 2000 kg and approximate size of a container (12.2 m) allowing easy transport and installation next to the contamination site.

[0104] The centrifugal clarifier 10 works in the outlet of the emulsion composed of the washing solution SLAV (H20+PL)+contaminants C from washing equipment 1 and performs the clarification that aims to remove most of suspended solids contained in said emulsion. The emulsion in this stage of the process contains water, modified terpenes, hydrocarbons removed from the contaminated soil and a percentage between 10% and 30% of suspended solids having particle diameter less than 0.56 mm. This clarification process is done by means of a centrifugal clarifier, of the two outlet streams type: washed solids outlet SL, having moisture content between 11% and 20%, which is joined to the recovered soil SR and a water solution outlet, PL modified terpenes, hydrocarbons C and a percentage lower than 2% of suspended solids S (clay) which binds the centrifuge 20.

[0105] The centrifuge 20 performs centrifugation, the last stage of the recovery process of the washing solution SLAV, which will be sent back to the washing process of new contaminated soil. Centrifugation is performed by a vertical centrifuge having three stages. The mixture, upon leaving the clarification process 10, is fed to the centrifuge 20 wherein the hydrocarbon that contaminated the soil is recovered (recovered contaminant CR) and sent to a storage tank 21. The recovered washing solution SLAVR (modified terpene emulsion+water) is sent to the feed tank 7 of the washing process for reuse. A third PI (intermittent purging) stream occurs at a specific outlet to which the solids are sent and can be added to the washed soil SL in the washing process.

[0106] Thus, in the present system, the compact unit formed by soil washing equipment 1, centrifugal clarifier 10 and centrifuge 20, contaminated soil feed means 2, feed means 7 of the washing solution SLAV, the place of origin O, from which the contaminated soil SC is remove and the process P from which the contaminants C originate are arranged substantially in a closed circuit and so as not to form disposable waste, unlike the conventional soil recovery process.

[0107] In fact, there are a series of costs in conventional processes. The most significant costs are variable and relate to the technology applied and the transport. Transportation costs may be the highest in the chain because, depending on the place of origin of the contaminated soil and their place of destination, these values may reach more than 50% of the composition of the costs. That is, in the worst case more than 50% of the costs do not add anything to the process but greater risks (displacement of hazardous waste) and higher CO2 emissions.

[0108] The process object of the present invention, in turn, eliminates the need for transport, as the waste is treated in situ and after its treatment it can be returned to its place of origin. In addition, hydrocarbons are recovered and, as they have market value, they can add a revenue component to the equation. That is, the claimed process reduces the steps that add costs and adds a revenue component.

[0109] The presently claimed soil recovery system, in fact, consists of an innovative model that can modify the current market rules bringing advantages for environmental companies, thus favoring a more effective fight against pollution for the benefit, ultimately, society as a whole.

[0110] According to the new concept proposed in the system object of the invention, the contaminated soil is brought to the washing process, this process generates clean soil, and the oil and washing solution based on modified terpenes and/or terpenoids are recovered, and the clean soil is backfilled at the place of origin. The recovered oil can provide revenue for the process and the recovered washing solution based on modified terpenes and/or terpenoids can be reused in the washing process, and there may be occasional disposal of the modified terpenes and/or terpenoids solution in the order of 0.025 m3/ton of recovered soil.

[0111] Having described preferred embodiments, it should be understood that the scope of the present invention encompasses other possible variations, and is limited only by the content of the appended claims, which include all possible equivalents.