WO2009044050A2 - Dry extraction of mineral oils - Google Patents

Abstract

Facility for the dry extraction of mineral oils contained in a mineral material, which comprises : a crushing/grinding unit (1) converting the mineral material so as to obtain a sand or granulate; a mixer/kneader (5), operating in batch mode or continuously, for mixing and obtaining intimate contact between the sand and a reversible sorbent introduced into the mixer/kneader (5) by a metering system. The facility includes a chamber (6) for blowing in a gaseous fluid that separates the mineral material from the reversible sorbent.

Description

 Dry extraction of mineral oils.

The present invention relates primarily to a dry extraction plant of mineral oils contained in a mineral material, for example sand and shale type. The invention further relates to a process for extracting such oils when agglomerated with these materials.

This problem is not new, extraction technologies exist and have been operating for a long time. However, they present a number of disadvantages that become more and more penalizing as the awareness of the need to preserve the environment comes to light. Thus, existing technologies require a very high energy consumption, in particular to produce the water vapor required for the various processes used, the production of energy having a direct impact on the emission of greenhouse gases. In addition, these processes consume in most cases large quantities of water, which poses the double problem of the scarcity of available water and discharges. Nowadays, water is no longer considered abundant and within everyone's reach, but it becomes precious.

Current technologies also lead to significant releases of residues, which are now often dumped and stored in lagoons. Entire sites are therefore soiled. Finally, on a strictly technical level, the processes used in many cases only result in incomplete extraction of the oils, which significantly reduces the operating efficiency of the existing installations and consequently their economic interest.

The overall result of these factors is a high extraction cost, further aggravated by the heavy impact on the environment. Current techniques are becoming more and more inadequate to the crucial challenges posed by the evolution of the world, resulting in particular from the foreseeable depletion of water, the control of greenhouse gas emissions, and the presence of sites with severe soil pollution.

The object of the present invention is therefore, in addition to an increase in the efficiency of current technologies, to significantly reduce the nuisance generated by their operation. The invention must in fact make it possible to improve the exploitation of oil sands and shale deposits by reducing their impact on ecosystems, so that the natural environment in which this exploitation takes place is not degraded. It should also be noted that the increase in yield, making it possible to extract a much larger quantity of mineral oils contained in the material, leads, as a corollary, to appreciably reduce the discharge of polluted materials into the environment.

To fulfill these objectives, and others that will appear on reading this description, the dry extraction plant of mineral oils contained in a mineral material of the invention comprises conventionally: a crushing-grinding unit transforming the mineral material to obtain a sand or granulate, a batch or continuous mixing-mixing mixer for mixing and obtaining an intimate contact between the sand and a reversible sorbent introduced into the mixer-mixer by means of a metering system.

It is characterized primarily in that it further comprises a gaseous fluid blowing chamber capable of separating the mineral material from the reversible sorbent agent. The first observation that is required is the following: unlike most existing technologies, based on a massive use of water, the extraction system of the invention operates by blowing for example air, which additionally simplifies considerably the entire installation. According to one possibility, the blowing chamber is disposed at a level lower than that of the mixer-mixer and fed by gravity from this last. In terms of energy control, the use of gravity makes it possible to save motor means for driving the flow of particles towards the blowing unit.

Preferably, the mixer-mixer and the blowing chamber are connected by a distribution duct distributing the mineral material and the sorbent in a laminar-like flow on an inclined surface subjected to the blowing of fluid.

In other words, the sands, particles, aggregates to be treated are conveyed on the blowing surface in the form of a flux or flow of surface appearance, that is to say of small thickness and more wide width.

More precisely, said inclined surface consists of a perforated grid, one side of which supports the laminar flow of the mineral matter particles and of the sorbent, and the other face is subjected to a gaseous flow oriented substantially perpendicularly to the grid. . The relative orientation of the grid and the flow of blowing fluid is to optimize the efficiency of the process, that is to say to reduce as much as possible the energy consumption for optimum separation of the particles of material to be treated. on the one hand, and sorbent on the other. In the present description, the terms "reversible sorbent agent", also known, must be understood as defining a product for fixing the mineral oils by surface effect, and to release them by mechanical desorption. The reversible sorbent can then be reused for a given number of extraction cycles. By way of example, it may be a cellular plastics material of the polypropylene, polyethylene or expanded polystyrene type, milled and processed in the form of aggregates adapted to the needs of the extraction process.

As for the mineral oils contained in the oil sands, they are hydrocarbons, which may be particularly dense, hence special measures that will be described below to make their extraction possible in the best conditions. The bottom of the discharge chamber, on the flow side, is provided with two so-called primary discharge ducts, located according to the blowing power so that they collect by gravity respectively the particles of mineral matter and sorbent agent. Preferably, the primary discharge pipe of the mineral material is disposed at the bottom of the flow grid, and the primary discharge pipe of the sorbent is disposed at the lower end of a wall facing the said grid, the blowing power being provided to blow only the sorbent agent towards said wall. Although the efficiency of blow separation is very high, it may be necessary, in some cases, to refine it before discharging and reintroducing the sands or aggregates removed from their hydrocarbons in their natural environment.

In this hypothesis, the primary discharge conduit of the mineral material opens onto a vibrating screen mat overcoming a recovery capacity of said deoiled mineral material, said carpet passing through the latter and filtering and driving to a secondary discharge duct a possible residue of sorbent agent.

According to one possibility, said belt may be provided with additional blowing means.

Furthermore, the primary discharge pipe of the sorbent agent, that is to say the one which is disposed at the outlet of the first step of separation by blowing, can optionally be provided with a venturi. Depending on the length of this pipe, it is more dynamic to drive the discharged sorbent particles. Assuming a second separation step, there are two sorbent agent discharge pipes, which meet before any subsequent treatment.

According to the invention, said one or more evacuation ducts open into a separating device separating the sorbent agent from the mineral oils which impregnate it, provided with an evacuation opening above a reservoir for said oils. The sorbent agent, who took care of the oil he removed sand or granules of mineral material, is in turn desorbed, so as to be reused if necessary. This second separation operation, distinct from the first, therefore aims to obtain on the one hand a reusable purified sorbent, and on the other hand mineral oils themselves treatable separately.

According to one possibility, this separation device comprises a compression screw. Alternatively, it can also be a centrifuge.

In many cases, as indicated above, the mineral oils that are to be extracted are, however, extremely dense hydrocarbons. It may then be necessary to use an additional solvent allowing a dilution of said hydrocarbons.

For this purpose, a mixer connected to a tank of solvent is placed between the outlet or channels of discharge of the sorbent agent and the aforementioned separation device. According to one possibility, such a mixer can be worm.

In the event of the existence of solvent, the oil tank placed below the device for separating the sorbent agent from the mineral oils is connected to an evaporator of the solvent, the vapors of which are conveyed to a condenser. - even connected to the solvent tank feeding the mixer. The use of solvent therefore operates, according to the invention, in a loop, since the liquid solvent obtained using the condenser is reinjected, via a reservoir, into the mixer for fluidizing the hydrocarbons.

In the same spirit, the installation of the invention makes it possible to recover the reversible sorbent agent after the step of separating the mineral oils, and to store it for a new use. For this purpose, the outlet of the separation device is connected to a treated sorbent storage tank.

This storage tank is itself connected to a metering hopper feeding the mixer-mixer by suitable means of routing. In the same way, a dosing hopper is arranged between the crushing-grinding unit and the mixer-mixer.

Preferably, there is provided between the crushing-grinding unit and said dosing hopper a screening unit by screening. This unit makes it possible in particular to remove the lumps or agglomerates possibly resulting from the crushing / grinding stage, to make it possible to optimize the work of separation carried out downstream.

So far, mention has been made of the blowing of a gaseous fluid. This is preferably air, whose orientation, speed and pressure are simply given by a carefully calibrated fan.

The installation of the invention makes it possible, at all operating stages, to reuse and recover the functional components of the depollution process, of the sorbent agent, solvent, etc. type. No chemical or toxic is released in nature and the only products released by the installation of the invention are mineral oils, which are found in the natural state, and sands or schists rid of their hydrocarbons. These can then be reintroduced into their natural environment without any additional treatment. As said, the sorbent can be reused, after the mineral oil separation step, during a predetermined number of sorption / desorption cycles, before being replaced.

The invention also relates to an extraction method, implemented in the installation described above, which consists in a known manner of:

- take the mineral matter; homogenizing the particle size of said mineral material to transform it into sand or granulate;

- intimately mix the mineral material with a specific quantity of a reversible sorbent;

kneading the mixture thus obtained for a predetermined period, to obtain a homogeneous diffusion of the reversible sorbent agent in the mineral material; separating the mineral matter freed from oils by the sorbent agent loaded with said oils.

According to its essential characteristic, this process is such that the separation is effected by blowing a gaseous fluid into an enclosure in which the mixture of mineral matter and sorbent agent continuously flows in the form of a laminar-type flow to which the blowing is applied.

As we have seen, to further refine the operation, the method may comprise a second separation step, downstream of the previous one, by sieving the mineral material and entrainment of the sorbent agent by means of a sieving belt vibrant.

Since the sorbent agent loaded with mineral oil is separated from the mineral material of sand or granular type, it is itself subjected, according to the method of the invention, to a desorption stage of the sorbent agent for the separation of mineral oils. In the case where the mineral oils are, for example, very dense hydrocarbons, this desorption step is preceded by a step of mixing a solvent with the sorbent agent. In this case, the oils mixed with the solvent are collected in an evaporator separating the oils from the solvent. The evaporated solvent is then condensed, so that it can be reinjected in the liquid state into the loop, that is to say, be recycled for reuse in an operational phase in order to dilute the hydrocarbons.

The invention will now be described in more detail, with reference to the single figure, showing a schematic representation of an exemplary embodiment of an installation according to the invention.

With reference to this figure, the crushing-grinding unit (1) makes it possible to transform the mineral material into sand or aggregates, in other words to control the granulometry of the raw material to be treated. A demoulding unit (2) is arranged downstream of the crushing-grinding device (1), in order to remove lumps or agglomerates by screening, in order to optimize the extraction process implemented downstream.

The material thus prepared is sent to a metering hopper, shown schematically in (3), which provides asphalt sand feed mixer-mixer (5). In parallel, a reservoir (4) of reversible sorbent agent also feeds the mixer-mixer (5) via a metering hopper (3 '). This reversible sorbent agent may in particular be made from a treated plastic honeycomb milled in the form of granules suitable for the extraction process of the invention. The mixer-mixer (5) is for example provided with rotating arms (5a) driven by an electric motor (M1). It is a device of the type concrete mixing plant, where any equivalent system of continuous mixing, whose objective is to allow an intimate contact between the sand or the bituminous aggregates on the one hand, and the sorbent agent reversible consisting of cellular particles of plastic material on the other hand. The mixing of the mixture obtained is carried out for a determined time, so as to obtain a homogeneous diffusion of the reversible sorbent agent in the mineral material, and a surface-effect fixing of the oils on said sorbent agent. At the end of the mixing-mixing step, the sand particles are in principle cleaned of their oil, whereas, conversely, the honeycomb particles of the sorbent agent are loaded with this material. Still closely mixed, they are guided in a funnel-shaped conduit (25) at the exit of which they flow on an inclined grid-like surface (26) integrated with a blow-off device (6). This is schematically as a sort of hopper, one of which is constituted by said grid surface (26), the opposite wall (13) being full. An air blower (27), in this case a fan, emits a flow of air through the grid (26) and separates the particles according to their density. In this case, the granules of mineral matter are not or only slightly affected by the flow of air, whereas the particles of sorbent agent are much lighter since they consist of cells of material synthetic, for example of the expanded polystyrene type, are pushed towards the opposite full wall (13). At the bottom of the hopper, two ducts (28, 29) serve respectively to discharge the particles of mineral matter and sorbent by gravity. In the example shown, a new separation is carried out using a vibrating belt (7), sieving the very small particles of the mineral matter. These flow by gravity to a storage tank (21). Vibrations of the vibrating belt (7) are calculated such that they drive the residual particles of sorbent to the left, so as to send them to a secondary pipe (30). A venturi device (31) equips the primary conduit (29) to impart motion to the sorbent particles which are then transported downstream of the circuit. The sorbent particles originating from the primary (29) and secondary (30) pipes are sent to a mixer (14) in which a diluent, for example of the C5 type, is injected in order to facilitate the desorption phase. following. The diluent, as already mentioned, aims to make less dense the hydrocarbons that now charge the sorbent agent. It may be an endless mechanical screw device driven by a motor (M2). This step completed, the sorbent particles are conveyed to a separation device (17) for example consisting of a screw compression system (18) driven by a motor (M3). This separating device (17) results in separating the mineral oils (19) on the one hand, collected in a reservoir (20), and on the other hand the sorbent agent, reusable and sent for this purpose in a cooling device. intermediate storage (32) then to the aforementioned tank (4).

The sorbent agent is indeed in its initial state, and can again be reused for one or more cycles, by injection into the mixer-mixer (5) via the metering hopper (3 ').

When the mineral oils (19) recovered are the result of a mixture between the oils initially fixed on the sorbent agent and a solvent, a subsequent step aims to separate these two materials, especially for solvent reuse. Thus the mineral oil / solvent mixture is collected by a low temperature evaporator (22). The vapors of said solvent are then condensed in a condenser (23) and recycled to the reservoir (24). The example explained above is of course not exhaustive of the invention. This includes several variants for example of shape or configuration for the various elements (kneader, blowing device, etc.). It is also possible, depending on the density of hydrocarbons, to dispense with the solvent mixing step, etc.

Claims

1. Dry extraction plant for mineral oils contained in a mineral material, comprising: - a crushing-grinding unit (1) transforming the mineral material to obtain a sand or a granulate, - a batch-mixer (5) in batch form or continuously to mix and obtain an intimate contact between the sand and a reversible sorbent introduced into the mixer-mixer (5) through a metering system, characterized in that it comprises a blowing chamber (6) of a gaseous fluid separating the mineral material from the reversible sorbent agent. 2. Installation according to the preceding claim, characterized in that the blowing chamber (6) is disposed at a level lower than that of the mixer-mixer (5) and fed by gravity from the latter. 3. Installation according to the preceding claim, characterized in that the mixing-mixer (5) and the blowing chamber (6) are connected by a distribution duct (25) distributing the mineral material and the sorbent according to a flow type laminar on an inclined surface (26) subjected to fluid blowing. 4. Installation according to the preceding claim, characterized in that said inclined surface (26) consists of a perforated grid, one side supports the laminar flow of the mineral matter particles and sorbent agent, and the other side is subjected to a gas flow oriented perpendicular to the grid (26). 5. Installation according to the preceding claim, characterized in that the bottom of the blowing chamber (6), on the side of the flow, is provided with two primary discharge pipes (28, 29), located according to the blowing power so that they collect by gravity, respectively, the particles of mineral matter and the sorbent. 6. Installation according to the preceding claim, characterized in that the primary discharge pipe (28) of the mineral material is disposed at the bottom of the gate (26) of flow, and the primary discharge pipe (28) of the sorbent is disposed at the lower end of a wall (13) facing said grid (26), the blowing power being provided to blow only the sorbent agent towards said wall (13). 7. Installation according to one of claims 5 and 6, characterized in that the primary discharge pipe (28) of the mineral material opens on a carpet (7) vibrating screen surmounting a container (21) for recovering the deoiled mineral material, said carpet (7) passing the latter and filtering and driving to a secondary discharge pipe (30) a possible residue of sorbent agent. 8. Installation according to the preceding claim, characterized in that said belt (7) is provided with additional blowing means. 9. Installation according to one of claims 5 to 8, characterized in that the primary discharge pipe (29) of the sorbent agent is provided with a venturi (31). 10. Installation according to one of claims 5 to 9, characterized in that each discharge line of the sorbent agent opens into a separating device (17) ridding the mineral oils (19) which impregnate, endowed an evacuation opening above a tank (20) for said oils (19). 1 1. Installation according to the preceding claim, characterized in that the separating device (17) comprises a compression screw (18). 12. Installation according to claim 10, characterized in that the separating device (17) consists of a centrifuge. 13. Installation according to one of claims 10 to 12, characterized in a mixer (14) connected to a tank (24) of solvent is placed between the discharge duct (s) (29, 30) of the sorbent and the separation device (17). 14. Installation according to the preceding claim, characterized in that the mixer (14) is worm. 15. Installation according to one of claims 13 and 14, characterized in that the oil reservoir (20) placed below the separation device (17) of the mineral oil sorbent (19) is connected to a evaporator (22) of the solvent, the vapors of which are conveyed to a condenser (23) connected to the tank (24) of solvent supplying the mixer (14). 16. Installation according to one of claims 10 to 15, characterized in that the outlet of the separating device (17) is connected to a reservoir (32) for storage of treated sorbent agent. 17. Installation according to the preceding claim, characterized in that the storage tank (32) of sorbent agent is connected to a metering hopper (3) feeding the mixer-mixer (5) by suitable conveying means. 18. Installation according to any one of the preceding claims, characterized in that a metering hopper (3) is disposed between the crushing-grinding unit (1) and the mixer-mixer (5). 19. Installation according to the preceding claim, characterized in that a sieving unit (2) by screening is interposed between the crushing-grinding unit (1) and the metering hopper (3). 20. Installation according to any one of the preceding claims, characterized in that the blowing fluid is air. 21. Process for the dry extraction of mineral oils contained in a mineral material, based on the extraction plant according to the preceding claims, comprising: - collecting the mineral matter; homogenizing the particle size of said mineral material for the transform into sand or granulate; - intimately mix the mineral material with a specific quantity of a reversible sorbent; kneading the mixture thus obtained for a predetermined period, to obtain a homogeneous diffusion of the reversible sorbent agent in the mineral material; separating the mineral matter freed from oils with the sorbent agent loaded with said oils; characterized in that the separation is effected by blowing a gaseous fluid into an enclosure (6) in which the mixture of mineral matter and sorbent agent continuously flows in the form of a laminar-type flow to which the blowing. 22. Extraction process according to the preceding claim, characterized in that it comprises a second separation step, downstream of the previous one, by sieving the mineral material and driving the sorbent agent by means of a carpet ( 7) Vibrating sieves. 23. Extraction process according to one of the preceding claims, characterized in that it comprises a desorption step of the sorbent for the separation of mineral oils (19). 24. Extraction process according to the preceding claim, characterized in that the desorption step is preceded by a step of mixing a solvent with the sorbent agent. 25. Extraction process according to the preceding claim, characterized in that the oils (19) mixed with the solvent collected after separation from the sorbent agent are collected in an evaporator (22) dissociating the oils of the solvent. 26. Extraction process according to the preceding claim, characterized in that the evaporated solvent is condensed and recycled for reuse.