WO2007006990A2 - Method for making carbon powder and installation therefor - Google Patents

Abstract

The invention concerns a method including the execution of the flowing steps: drawing a mineralized solid carbon-containing product and introducing same in a pressure grinder (2) and circulating ground products by means of a fluid having a carrier function; evacuating the carbon particles and the particles of other minerals by pneumatic conveyor means towards a centrifuging zone (Z2) enabling the carbon to be separated from the other minerals; performing a centrifuging operation with separation between the carbon particles and the other minerals transported by a gaseous fluid towards means for separating the carbon particles and the carrier gas; and collecting the particles of the other minerals in output of the centrifuge in a recovery tank; performing a separating operation of the carbon particles and the carrier gas at the output of the centrifuge in a zone (Z3), said gases being recycled; evacuating the resulting carbon particles in the form of carbon powder for storage packaging and sale; performing a recycling operation on the carrier gaseous fluid. The invention also concerns an installation for implementing the method.

Description

 CARBON POWDER MANUFACTURING METHOD AND IMPLEMENTATION INSTALLATION

The invention relates to the technical sector of the exploitation and regeneration of carbon-based materials included in products of any kind.

The sources of carbon production are diverse with varying qualities. Natural graphite carbon is generally present in deposits in the form of flecks, flakes or veins, used mainly for its refractory qualities, lubricating properties and its high chemical resistance, artificial carbons such as artificial graphite, animal black, charcoal wood, pyrocarbon, activated carbon, coke, carbon black. The use of carbon, natural or artificial, in applications, including various industrial applications, such as the use of its properties for the purpose of increasing the hardness for tools, the manufacture of tires, electrodes, molds, crucibles, nozzles, lubricants, refractory materials, electrical protections or other applications in steel, chemical engineering, foundries, nuclear, given only by way of non-limiting example, becomes considerable, because of the many properties of this material. For all types of carbon, the constant is in the cost, which can be very high, since it can go up to 7,500 Euros per ton for graphitic carbon, from 800 to 1,400 Euros per ton for carbon black.

All this demonstrates the multiplicity of origins of production with important varieties between products and their costs. The Applicant's approach was to consider existing carbon products on the market, containing carbon or carbon particles as well as other minerals, and to study the treatments they have undergone in order to adapt them to others. applications. More particularly, the Applicant has been interested in the manufacture of carbon powder from carbonaceous mineral products, these products themselves being obtained, for example and without limitation, from the treatment or recycling of organic solids, especially recycling. treated or impregnated wood such as electric or telephone poles, railway sleepers or demolition wood.

Carbonaceous products, composed of carbon and other minerals, come for example from the implementation of the process known under the trademark "CHARTHERM" (semi-figurative) and whose technology is defined in particular in the European Patent No. 772,663 .

The carbon products thus obtained, composed of carbon and other minerals, such as for example heavy metals, are themselves reusable for certain applications.

In practice, this or these reuses are of low added value, because the carbon products are used as such. The Applicant optimizes the process described in Patent No. EP ⁰ 772 663 in an alternative embodiment, described in French patent application No. 05 51 335 complementary, which implements a solid organic distillation operation for the product obtained carbon, largely composed of carbon, constituting a secondary raw material with substances other than carbon still in a certain proportion, but satisfactory for certain applications.

The Applicant's approach was to go even further and to think of a process for separating the carbon particles from the other mineral substances in order to produce carbon powder having a very high degree of purity of the order of 95% to 99.9% and can be used as a noble secondary raw material especially in the applications mentioned above.

This approach has led the Applicant to implement a process and an installation for implementing said process, suitable for the manufacture of carbon powder, from carbonaceous products, obtained for example and without limitation by the "Chartherm" process cited above. above, but also and more generally, by treating mineral products incorporating a large proportion of carbon particles, for the recovery of the noble mineral material, carbon.

According to a first characteristic, the method consists in the execution of the following phases:

- sampling of a mineralized solid carbon product including carbon particles and particles of other minerals, and introduction into a pressure mill to crush the carbon product to reduce the particle size, the strength of crushing being adjusted so as to break the structure of the carbon matrix and to release the other minerals from the carbon matrix which coats them while trying to preserve their initial size, and circulating the crushed products by a fluid having a function of transport. - Evacuation of carbon particles and particles of other minerals by pneumatic transport to a centrifugation zone (Z2) allowing the separation between carbon and other minerals including heavy metals.

- Centrifugation operation with separation between the carbon particles and the other minerals under the effect of their difference in density, with evacuation of the carbon particles transported by a gaseous fluid to means for separating the carbon particles and the transport gas and collecting other separated minerals at the outlet of the centrifuge in a recovery tank.

- Separating operation of the carbon particles and the transport gas at the outlet of the centrifuge in a zone (Z3), said gases being recycled.

- evacuation of the resulting carbon particles in the form of carbon powder for their storage and sale packaging.

- Operation of recycling the gaseous transport fluid.

The method thus described will be detailed in the following description.

The process implementation installation includes:

means for feeding the carbonaceous products and transferring them to a pressure mill,

means allowing pressure grinding of the carbon product provided with means for controlling the physical parameters of this grinding,

means allowing the continuous supply of a gaseous transport fluid, responsible for transporting the carbon particles and the particles of other minerals and circulating the gaseous transport fluid in a circuit closed continuously until the separation between the gaseous transport fluid and the carbon particles,

means allowing by centrifugal separation the separation between the carbon particles and all the other mineral particles, including heavy metals,

separation means between the carbon particles and the gaseous transport fluid,

means for transferring the clean carbon particles, collected in the form of carbon powder, with a view to their conditioning,

means for conditioning the clean carbon powder,

means for recycling the gaseous transport fluid.

The installation will be described in more detail below.

These and other characteristics will be apparent from the rest of the description.

For fixing the object of the invention illustrated in a nonlimiting manner to the figures of the drawings where:

- Figure 1 is a schematic view of the installation according to the invention.

- Figure 2 is a schematic view of the pneumatic centrifuge.

In order to make the object of the invention more concrete, it is now described in a nonlimiting manner illustrated in the figures of the drawings. The treated solid carbon products are based on carbon and various minerals, some of which are metallic. They are for example from the implementation of the "CHARTHERM" process as described in the aforementioned European Patent EP 772,663 or French Patent Application No. 05 51335.

The invention relates to the treatment of these carbonaceous products, resulting from this process in its different versions, or from any other technology, for the purpose of distinguishing and manufacturing, after extraction of mineral particles other than carbon, carbon powder from the almost pure state for use in different applications.

For this purpose, the installation comprises means in the form of a hopper (1) capable of collecting the solid carbonaceous products conveyed to it by carriers and presenting them to a first zone (Z1) intervention and materialized treatment by the use of a pressure mill (2), for example pendulum mill. This crusher makes it possible to reduce the particle size of the carbon product and to break the structure of the carbon matrix while trying to preserve the size of the minerals other than the carbon present in the carbon product, these minerals being released from the carbon matrix which makes them coated, and obtain at the output of the mill a particle size distribution poorly dispersed around the average size of the particles. This mill (2) is equipped with the following components: a hopper (1) for supplying the carbonaceous products, a honeycomb valve (3) acting on the input flow rate of the carbonaceous products in the mill. In addition, said mill is arranged in its lower part with a pneumatic system (4) for recovering the products resulting from the grinding to transport them to the pneumatic separator (7) whose function is to reduce the width of the size distribution of the particles coming out of the grinder and return to the mill the particles considered too large. The neutral transport gas is introduced into the lower part of the mill (4) by means of a blower (5) introduced into a closed air circuit from a means (6) serving as a reservoir-lung . The pneumatic separator (7) has an outlet pipe (8), allowing the circulation of the gas transporting the various carbon particles and other minerals.

The transport of these carbon particles and other minerals is carried out by the appropriate pipe (8) being transported by the gases according to the pre-established distribution circuit to a second so-called centrifugation zone (Z2). This is arranged to allow separation between the carbon particles and the other mineral particles including heavy metals.

The pneumatic centrifuge (9), shown in FIG. 2, thus comprises an inlet (9a) for admitting solid particles from the mill and transported by the gases, an outlet (9b) for the carbon particles and internally a baffle drum ( 9c) whose rotation causes the formation of a rotating air cushion on itself. In addition, the lower part of the centrifuge is arranged with a recuperator (10) to collect inorganic particles other than carbon.

A depression is created in the center of the centrifuge by means downstream, namely a main fan (23), through a filter box (18) and a cyclone (14). This depression attracts the particles orthogonally from the periphery to the center. The most particles heavy, that is to say the particles consisting of minerals other than carbon, through the air cushion formed by the rotation of the baffle drum undergo centrifugal acceleration, directly proportional to their mass, which deviates from their initial trajectory and projects at the periphery of the air cushion, towards the walls of the centrifuge. In contact with the wall, these particles lose their speed and fall, by gravitation, down the centrifuge. Their evacuation is done through a cellular valve (12) which seals between the transport flow circuit and the recovery tank (10) installed under the centrifuge. The carbon particles, having a density too low to undergo the accelerating influence of the rotating air cushion, are not deviated from their trajectory and go directly to the center of the centrifuge.

At this stage, that is to say in the center of the centrifuge, the depression created by the main fan (23) causes the carbon particles that are transported by the gaseous fluid, through the cyclone where a first separation takes place. between the carbon particles and the gaseous fluid. However, the experiment showed that at the exit of the cyclonic equipment, the transport gas could still convey very fine particles of carbon. Also, downstream of the cyclone equipment is provided complementary equipment consisting of a filter box (18), connected by the pipe (15). The depression created by the main fan (23) causes the flow of gas through the filter box where takes place the second separation between the carbon particles and the transport fluid. Once it has passed through the filters, the transport gas is evacuated by the main fan (23) to the lung while the carbon accumulated on the filter walls falls into the bottom of the filter box under the influence of the cyclic countercurrent declogging. Carbon particles, fallen into the bottom of the cyclone after the first separation, pass through a honeycomb valve (16) and fall into a linear conveyor (17). This gives a certain mass of carbon powder which will then be transported to a packaging system. The mass of carbon powder accumulated at the bottom of the filter box passes through a honeycomb (19) and falls into the aforementioned linear conveyor (17).

The reservoir-lung (6) which is therefore located between the blower (5) and the suction blower (23) is shaped as a reservoir. He enters this reservoir-lung as much gaseous fluid as it leaves. This fluid incorporates nitrogen (6a) to start the operation of the installation and to maintain a gaseous atmosphere neutral controlled overpressure.

The nitrogen is fed into the lung reservoir from a nitrogen generator not shown in the drawing. The fluid distribution circuit is thus perfectly defined and allows fluid circulation in the different successive zones (Z1, Z2, Z3) in addition to the complementary bypass (11) of the reservoir-lung to the centrifuge facilitating the introduction of the particles. in the centrifuge.

The portion of pipe between the tank-lung (6) and the fan (5) is referenced by (24) and that between the blower (5) and the mill (2) is referenced by (30). The complete fluid circuit from the reservoir-lung is defined by the pipe portions (24), (30), (31), (8), (13), (15), (28). This circuit is a sealed closed circuit that does not communicate with the outside. Honeycomb valves (3) (12) (16) (19) ensure the flow tightness vis-à-vis the outside and at the product inlets and outlets.

Incidentally, for the control of the gas flow before the mill (2), it can be provided a bypass (25) including a control valve (26).

The installation runs continuously.

Without departing from the scope of the invention, the filtration apparatus downstream of the cyclonic equipment can be arranged with several filtration stages to refine at most the capture of the carbon particles, so that the transport gas once recycled may be free or virtually free of any particles.

The process according to the invention thus makes it possible in a new way from the recovery of mineralized organic products by processes, such as for example the "CHARTHERM" process in its various variants, to produce carbon powder with a very high degree of purity. Student.

Carbon recovery according to the process thus becomes a new source of carbonaceous product treatment and carbon powder production which is in areas of very competitive cost compared to carbon technologies of the prior art.

Bag packaging of carbon powder is a possible mode for its distribution. Of course, various known means can be used for conditioning, weight control, extraction of air during filling of the bag, control of fluidity of the carbon powder with use of anti-arch systems.

The invention provides a very important progress and allows the recycling and development of this noble material for other applications.

Claims

R E V E N D I C A T IO N S -1- A method of manufacturing carbon powder, characterized in that it consists in the execution of the following phases: taking a mineralized solid carbon product and including carbon particles and particles of other minerals, and introducing it into a pressure mill (2) to crush the carbon product in order to reduce the particle size; crushing force being adjusted so as to break the structure of the carbon matrix and to release the other minerals from the carbon matrix which coats them while trying to preserve their initial size, and circulating the crushed products by a fluid having a transport function, - evacuation of carbon particles and particles of other minerals by pneumatic transport to a centrifugation zone (Z2) allowing the separation between carbon and other minerals including heavy metals, - Centrifugation operation with separation between the carbon particles and the other minerals under the effect of their difference in density with evacuation of the carbon particles transported by a gaseous fluid to separation means of the carbon particles and the transport gas, and collecting the particles of the other minerals leaving the centrifuge in a recovery tank, - Operation of separating carbon particles and transport gases at the outlet of the centrifuge in a zone (Z3), said gases being recycled, - evacuation of the resulting carbon particles in the form of carbon powder for their storage packaging and sale, - Operation of recycling the gaseous transport fluid. -2- Installation for implementing the method, according to claim 1, characterized in that it comprises: means for feeding the carbonaceous products and transferring them to a pressure mill (2), means allowing pressure grinding of the carbon product provided with means for controlling the physical parameters of this grinding, means allowing the continuous supply of a gaseous transport fluid, responsible for transporting the carbon particles and the particles of other minerals and circulation of the gaseous transport fluid in a continuous closed circuit until the separation of the particles of carbon, means allowing, by centrifugal separation, separation between the carbon particles and all the other mineral particles, including heavy metals, comprising a pneumatic centrifuge (9), comprising an inlet (9a) for admitting solid particles from the mill and carried by the gases, an outlet (9b) of the carbon particles and internally a baffle drum (9c) whose rotation causes the formation of a rotating O-ring air cushion on itself, and in that the lower part the centrifuge is arranged with a recuperator (10) of mineral particles other than carbon, and in that a depression created in the center of the centrifuge attracts the particles which enter the centrifuge orthogonally from the periphery to the center, separation means between the carbon particles and the gaseous transport fluid, means for transferring the clean carbon particles, collected in the form of carbon powder, with a view to their conditioning, means for conditioning the clean carbon powder, means for recycling the gaseous transport fluid. -3- Installation according to claim 2, characterized in that it comprises means in the form of hopper (1) capable of collecting solid carbonaceous products conveyed to it by carriers and present them to a first zone ( Zl) of intervention and treatment materialized by the use of a pressure mill (2), and in that the mill (2) is equipped with the hopper (1) for feeding solid carbonaceous products, a honeycomb valve (3) acting on the inlet flow rate of the solid carbonaceous products in the mill, and in that said mill is arranged in its lower part with a pneumatic system (4) making it possible to recover the products resulting from the grinding for the transport to the pneumatic separator (7), -4- Installation according to claim 3, characterized in that it comprises, in addition to the mill, a pneumatic selector (7) whose function is to reduce the width of the particle size distribution leaving the mill and return towards the crusher the particles considered too big. and in that the pneumatic separator (7) has an outlet pipe (8), allowing the output of the ground product. -5- Installation according to any one of claims 2 and 3, characterized in that the routing of the different types of particles, which are transported by the gas according to the preset distribution circuit, is effected by the pipe (8). ) to a second so-called centrifugation zone (Z2), and in that it is arranged to allow separation between the carbon particles and the other mineral particles including heavy metals. -6- Installation according to claim 5, characterized in that it comprises a means (6) forming reservoir-lung whose function is to balance the transport gas flows in the circuit. -7- Installation according to claim 5, characterized in that a depression, created in the center of the centrifuge by the main fan (23), through the filter box (18) and the cyclone (14) attracts the particles which enter the centrifuge orthogonally, from the periphery to the center. -8- Installation according to claim 5, characterized in that the particles of minerals other than carbon, having a higher density, through the air cushion formed by the rotation of the baffle drum, undergo a centrifugal acceleration, directly proportional to their mass, which deviates them from their initial trajectory and throws them at the periphery of the air cushion, towards the walls of the centrifuge at the contact of which the particles lose their speed and fall, by gravitation, into the lower part of the centrifuge , and in that the carbon particles having a density too low to undergo the accelerating influence of the rotating air cushion, are not deviated from their path and go directly to the center of the centrifuge. -9- Installation according to claim 5, characterized in that the evacuation of mineral particles other than carbon is obtained by the incorporation of a honeycomb valve (12) which provides sealing between the transport flow circuit and the recovery tank (10) installed under the centrifuge. -10- Installation according to any one of claims 2, 3, 5 and 8 characterized in that the fluid mixture / carbon particles from the centrifuge (9) is conveyed in a conduit (13) and is directed to a cyclonic equipment (14) which allows a separation between the transport gas stream and the carbon particles, and in that downstream of the cyclonic equipment complementary equipment is provided consisting of a filter box (18), connected by the pipe (15), and in that the filter box, consisting of a closed chamber provides additional filtration with suction of the transport gas, evacuated by the main fan (23), -11- Installation according to claim 10, characterized in that the transport gas is discharged through a pipe (14a) disposed in the upper part of this equipment to be discharged through a pipe (15), and that the carbon particles of a certain density fall into the bottom of the equipment (14) and are recovered through a honeycomb valve (16) which seals between the transport flow circuit and the linear conveyor (17), and in that the recovery of the carbon particles is carried out by a periodic unclogging of the filters, the carbon particles then being conveyed towards the bottom of the filtration apparatus to be evacuated via a honeycomb valve ( 19) which seals between the transport flow circuit and the linear conveyor (17). -12- Installation according to claim 10, characterized in that the carbon particles from the cyclonic equipment, or the filtration apparatus, are collected by the conveyor (17) and conveyed via complementary transfer means such as carrier (20), hopper (21) in bag-type storage means (22) or the like. -13- Installation according to claim 10, characterized in that the gaseous fluid this time free of carbon particles is removed from the filtration apparatus (18) by another pipe (28) which is connected to the reservoir-lung, a suction fan (23) and a fluid circulation accelerator facilitating the recycling of the fluid, and in that the fan (23) participates in the operation of the fluid transport circuit by facilitating and permitting the suction of the gases through the filter box and the cyclone, thus creating a depression in the center of the centrifuge. Installation according to claim 3, characterized in that the reservoir-lung (6), which is situated between the blower (5) and the suction blower (23), is in the form of a reservoir in which between as much gaseous fluid as it emerges, and in that the fluid incorporates nitrogen to start the operation of the installation and to maintain in the gaseous circuit a gaseous atmosphere neutral controlled overpressure . Installation according to any one of claims 2 to 14, characterized in that the complete circuit of the fluid, from the reservoir-lung, is defined by the pipe portions (24), (30), (31). ), (8), (13), (15), (28), and in that this circuit is a sealed closed circuit which does not communicate with the outside, the cellular valves (3) (12) (16) (19) sealing the flow vis-à-vis the outside and at the product inlets and outlets. -16- Installation according to claim 15, characterized in that, for the control of the flow of fluid before the mill (2), it can be provided a bypass (25) including a control valve (26), in order to regulate the flow of gaseous fluid injected into the pressure mill.