METHOD FOR SHAPING BIOMASS POWDER INTO BEADS

Abstract

A biomass processing method for producing biomass pellets suitable for use in a gasification process, the method comprising the following steps: a) providing a first solution containing algae and carbonates, the first solution preferably being at a temperature between 30 and 60 °C, b) adding biomass powder to the first solution, thereby forming a second solution, the particle size of the biomass powder preferably being less than 1000 µm, c) adding dropwise, for example by means of an injection nozzle preferably having an outlet orifice of 1 mm to 20 mm in diameter, the second solution to an ionotropic coagulation bath comprising divalent ions, thereby forming biomass pellets suitable for use in a gasification process. Figure 1.

Description

Title of the invention: METHOD FOR SHAPING A BIOMASS POWDER INTO THE FORM OF BEADS Technical field

[0001] The present invention relates to the general field of shaping powders from biomass (raw or treated by thermochemical conversion).

[0002] The invention relates to a method for treating biomass and waste to agglomerate them in the form of “balls”.

[0003] The invention also relates to biomass balls thus obtained.

[0004] The invention also relates to a biomass gasification process using work of such marbles.

[0005] The invention is particularly interesting since it makes it possible to form biomass balls of calibrated size and of quasi-spherical shape. These balls have good flowability properties and can be stored without risk of explosion or compaction.

[0006] The invention finds applications in numerous industrial fields, in particular for the gasification of biomass (for example dust and other fine-sized carbonaceous waste in industry, for example in the paper industry) or for the production of fertilizers. STATE OF THE PRIOR ART

[0007] In order to address energy dependence on fossil hydrocarbons, one of the most promising solutions is the production of synthesis gas (Syngas) and molecules of interest from biomass and / or carbon waste (resource).

[0008] The recovery of carbon products (biomass and waste) can be carried out by a gasification process (thermo-conversion) in an entrained flow reactor (EFR). This process consists of gasifying the resource, typically at temperatures ranging from 900°C to 1400°C and pressures ranging from 1 to 30 bar, to obtain a synthesis gas composed essentially of carbon monoxide (CO), dihydrogen (H2) and carbon dioxide (CO2). From CO and H2, it is then possible to obtain CH2 hydrocarbon chains similar to those from fossil hydrocarbons and thus manufacture a synthetic fuel. The carbon is thus recovered in the form of methane or syngas to produce fuels.

[0009] The gasification process also makes it possible to co-generate heat and electricity.

[0010] Conventionally, before implementing the gasification step, the resource is mechanically pretreated, through a grinding step to adapt the size of the particles to the conveying and injection system of the gasification reactors (typically less than 2 mm). This step is carried out using different grinding technologies, for example knife mill, hammer mill, chain mill, etc.

[0011] The grinding step also leads to the formation of fine particles with dimensions less than 200 μm. Fine powders containing lignocellulosic components are cohesive and elongated, which leads to flow difficulties due to the electrostatic attraction (Van der Waals forces) between the walls of the reactors and the powder. These fine particles, generally difficult to convey, also increase ATEX (explosive atmosphere) risks and cause blockage problems throughout the system, leading to process shutdown.

[0012] To avoid these drawbacks, fine particles (<200 pm) are separated from other particles by industrial screening equipment and they are generally little or not at all recovered.

[0013] However, the fraction of fines can thus represent from 20 to 50% by mass of the ground material (depending on the severity of the grinding and the friability of the resource).

[0014] It is therefore essential to be able to recover this fine powder, for example by transforming it into granules.

[0015] In order to be used in a gasification reactor, the granules must have a diameter between 200 pm and 3 mm. Fine powders with particle sizes less than 200 pm have blocking problems. Powders with dimensions greater than 3 mm have low thermo-conversion efficiencies because the residence times of the input in the reactor are short (a few seconds).

[0016] Different techniques exist for forming granules from fine particles, notably wet granulation.

[0017] For example, in document FR 3 059 008 A1, granules are obtained from a wet granulation process of biomass. The process comprises the following steps:

[0018] - drying of biomass,

[0019] - crushing of biomass,

[0020] - wet granulation of biomass in the presence of a binder, in particular starch, whereby wet granules are formed,

[0021] - drying to obtain dry granules and, possibly, sieving.

[0022] The granules are then injected into a gasification reactor. Satisfactory results concerning the flowability of the granules have been obtained. However, this process has some drawbacks: the particle size of the granules is not homogeneous, hence the implementation of a sieving step (sieve size: 900 μm), and a drying step is necessary (spreading the granules in thin layers then drying at room temperature for 8 hours), which complicates the process. In addition, the Pellets disintegrate easily, which poses a problem for their transportation and conveyance in gasification plants.

[0023] In other technical fields, in particular the food industry or pharmacy, there are encapsulation methods for forming beads with a liquid core / gelling agent shell structure. For example, in document FR 2 964 017 A1, the method comprises the following steps:

[0024] - separate conveyance in a double envelope of a first liquid solution containing the first product (active ingredient) and a second liquid solution containing a liquid polyelectrolyte to be gelled, for example alginate,

[0025] - formation of a series of drops each comprising a central core containing the active ingredient, and a peripheral film completely covering the central core,

[0026] - contacting the drop, formed in a gaseous volume at the outlet of the double envelope, with a gelling solution.

[0027] - immersion of each drop in a gelling solution containing a reagent capable of react with the film electrolyte.

[0028] The capsules obtained contain a liquid core and a gelled external surface. However, such capsules are fragile (poor mechanical strength over time). In addition, they have a high humidity level (typically greater than 80% m) and therefore cannot achieve good energy efficiency in a gasification reactor such as an entrained flow reactor (EFR).

[0029] In addition, the beads produced by this process are of submillimetric sizes (particle size less than 500 pm). A drying step of these beads involves a reduction in particle size (syneresis effect of the gels), which can become less than 200 pm, this is not suitable for a gasification installation, RFE type.

[0030] Finally, such a process is a batch manufacturing process, and the gelling bath is not recyclable, which complicates production on an industrial scale. Disclosure of the invention

[0031] An aim of the present invention is to propose a method for treating biomass leading to the formation of biomass balls having dimensions suitable for implementation in a gasification process and leading to a good gasification yield, the method having to be simple to implement, inexpensive and with a low, or even zero, impact on the environment, including in the context of implementation on an industrial scale.

[0032] For this purpose, the present invention proposes a method for treating biomass to manufacture biomass balls suitable for use in a gasification process, the method comprising the following steps:

[0033] a) providing a first solution containing algae and carbonates, the first solution preferably being at a temperature between 30 and 60°C, even more preferably between 30 and 50°C,

[0034] b) adding a biomass powder to the first solution, whereby a second solution is formed, the particle size of the biomass powder preferably being less than 1000 pm, and even more preferably less than 200 pm,

[0035] c) adding dropwise, for example by means of an injection nozzle preferably having an outlet orifice of 1 mm to 20 mm in diameter, the second solution to an ionotropic coagulation bath comprising divalent ions, whereby biomass beads suitable for use in a gasification process are formed.

[0036] The invention differs from the prior art in particular by the use of algae to recover the biomass. The algae make it possible to form alginate during step a).

[0037] Alginate is a natural polysaccharide obtained from algae. Alginate has the particularity of instantly forming a hydrogel in the presence of multivalent ions, and in particular divalent ions. The carboxyl groups of alginate have the property of chelating divalent ions of opposite charge (for example Ca2+), leading to the formation of rigid three-dimensional networks. This is called an "ionotropic" hydrogel.

[0038] By hydrogel is meant a hydrophilic polymer network capable of absorbing up to several thousand times its dry mass in water.

[0039] Thus, when the alginate present in the second solution in step b) comes into contact with the divalent ions of the ionotropic bath, an ionotropic hydrogel. The injection, carried out drop by drop in the ionotropic coagulation bath, leads to the formation of beads (also called spheres).

[0040] Preferably, the algae are brown algae, optionally mixed with other algae, the brown algae representing at least 50% by mass of the mixture. Advantageously, the brown algae are Sargassum algae, Fucus ve-siculosus algae or Laminaria algae. The other algae may be chosen from green algae, red algae and microalgae. The algae used in the process are preferably so-called invasive algae. Thus, the process makes it possible to recover not only the biomass particles but also the algae.

[0041] According to an advantageous embodiment, the ionotropic coagulation bath is an aqueous solution of calcium nitrate.

[0042] According to another advantageous embodiment, the ionotropic coagulation bath is an aqueous solution of calcium nitrate and potassium nitrate. The addition of potassium nitrate to the coagulation bath improves the catalytic effects during the RFE gasification process, the thermo-conversion is improved.

[0043] Advantageously, the ionotropic coagulation bath has a pH between 3 and 7.

[0044] Advantageously, step c) is carried out by means of an injection nozzle, preferably having an outlet orifice of 1 mm to 20 mm in diameter. The use of a nozzle reduces the width of the particle size distribution: there are fewer possible rearrangements between the grains, an increase in porosity and a reduction in compaction. This is of interest for flowability, by reducing the risks of arching / blocking.

[0045] Advantageously, during step a), the first solution comprises carbonates, preferably sodium carbonates, and optionally propionates, preferably sodium propionates. The use of propionates improves the preservation of the beads over time.

[0046] Advantageously, the algae / biomass mass ratio of the colloidal suspension is between 0.01% m and 50% m, preferably between 1% m and 10% m, for example 1% m.

[0047] Advantageously, the process comprises a subsequent step d) during which the biomass balls are dried, for example with pulsed air, preferably at a temperature between 0°C and 30°C. This step is particularly advantageous when the balls are used in a dry gasification process.

[0048] According to an alternative embodiment, the second solution obtained in step b) comprises divalent metals, preferably in ionic form (for example copper ions, nickel ions, zinc ions or a mixture thereof). The beads thus obtained can be calcined to form metal nanoparticles, which can be used as catalysts in different processes.

[0049] According to another embodiment variant, the second solution obtained in step b) comprises inorganic salts, originating for example from a hydrothermal reactor for separating salts in supercritical water. The beads obtained can be used as natural fertilizer.

[0050] Advantageously, the process is carried out continuously:

[0051] - step a) is carried out in a first reactor, the biomass being prepared and / or stored in a second reactor,

[0052] - step b) is carried out in a mixing tank, in fluid communication with an injection nozzle arranged opposite a tank containing the ionotropic bath,

[0053] - step c) of forming the biomass balls is carried out in the tank containing the ionotropic bath.

[0054] The tank is provided with an outlet arranged opposite an element provided with a multitude of openings, configured to evacuate the balls towards a drying device and making it possible to recover a liquid phase through the openings, the liquid phase being advantageously reinjected into the tank.

[0055] The tank is advantageously equipped with a pH probe.

[0056] This continuous process is simple to implement and the various elements of the installation are easy to use. The entire process can be carried out at room temperature (typically at a temperature between 20 and 25°C) and at ambient pressure (typically at a pressure of Ibar or 105 Pa). There is no need for expensive equipment, such as a cryogenic bath.

[0057] The method has numerous advantages, and in particular one or more of the following advantages:

[0058] - the fine biomass powder is distributed homogeneously within the balls,

[0059] - obtain micrometric sized beads (typically greater than 50pm and preferably greater than 200pm) and preferably millimetric in size, which limits the problems linked to the handling and conveying of fine powders: blockages, health risks (in particular cancers associated with wood powders or risk of Alzheimer's disease and / or lung cancer) and ATEX (risk of explosion linked to powders, etc.),

[0060] - produce rigid balls, which improves their flowability and therefore facilitates their conveying and injection into a gasification reactor, such as an entrained flow reactor,

[0061] - reduce the size distribution and modify the surface condition of the balls: the balls are smoother, and there are fewer rearrangements between the balls, which reduces powder-powder and powder-wall friction, thus avoiding blockages / vaults / consolidations,

[0062] - obtain marbles with an aspect ratio close to 1 (obtaining marbles spherical), which reduces conveying problems.

[0063] - modify the mechanisms of particle interactions (electrostatic forces, forces Van der Walls...) dependent on the particle size; which leads to an improvement in the flowability of fine particles,

[0064] - the agglomeration of the balls does not require any external intervention (the phenomenon occurs alone) and the energy expenditure linked to this agglomeration is zero,

[0065] - not having strong consolidation within the balls, which facilitates disintegration in reactor): the ball can be easily destroyed in RFE where the residence times are short because the particles are not strongly compacted,

[0066] - the properties of the particles are not modified by the mechanism agglomeration and once released they have the same behavior in gasification as if they had not been agglomerated into balls,

[0067] - have a binder that volatilizes easily in the reactor: the ball can disintegrate on a few seconds in RFE and the fine particles are released and gasified,

[0068] - have a link which promotes the penetration of reactive gases during gasification, this which increases gasification kinetics,

[0069] - to be able to recover dust and other fine carbonaceous waste from industry (e.g. dust collected in cyclones).

[0070] The invention also relates to biomass balls suitable for use in a gasification process. The biomass balls, obtained from the process described above, are rigid. The biomass is, for example, olive pits.

[0071] The beads comprise a homogeneous mixture of algae and biomass, the algae preferably being brown algae or a mixture of algae containing at least 50% by mass of brown algae.

[0072] Advantageously, the beads further contain a catalyst or inorganic salts. The catalyst is preferably a divalent metal, for example nickel, copper or zinc. The catalyst may also be formed from a mixture of these divalent metals.

[0073] Advantageously, the biomass beads comprise a homogeneous mixture of alginate and biomass.

[0074] The composition of the beads is homogeneous in surface and volume. The beads obtained do not have a core / shell structure. The alginate and biomass powder are found throughout the volume of the bead.

[0075] The beads may also contain inorganic species (calcium and, preferably, potassium) promoting the gasification kinetics by catalytic effect.

[0076] Advantageously, the aspect ratio of the balls is close to 1 (almost perfectly spherical shape). This considerably reduces conveying problems due to the interaction between the balls due to their morphology (roughnesses promoting snagging but also possibilities of rearrangement of grains in the interstices).

[0077] Advantageously, the balls have a diameter of between 1 mm and 20 mm.

[0078] This wet granulation leads to the formation of balls with a homogeneous size distribution and calibrated diameter. The balls are formed from a homogeneous mixture of algae and biomass (in surface area and volume).

[0079] Such beads are easy to convey and inject into gasification reactors (particularly entrained flow gasification reactors also called RFE). The fine particles are thus recovered.

[0080] Such beads allow the dosing and flowability of powders in a gasification reactor, which contributes to an improvement in the technical management of the process and to better conversion / valorization of the biomass.

[0081] The invention also relates to the use of biomass balls, as defined above, for example balls comprising olive stone powder.

[0082] The beads can be used as adsorbent products implemented in the treatment of liquid or gaseous effluents. The beads form a filter medium for adsorption of pollutants.

[0083] For example, they can be used to treat wastewater. They can be used in pollutant adsorption columns to treat / purify water upstream of the microalgae cultivation process (e.g. spirulina, chlorella vulgaris, etc.).

[0084] An increase in the porosity of the bed can promote the interaction between the fluid to be treated and the filter medium. If the particles are too nested, there is a risk that the fluid will not circulate correctly in the filter medium.

[0085] The balls obtained can be used in combustion boilers.

[0086] The beads obtained, when they contain catalytic elements in addition to biomass and algae, can be calcined to obtain nanoparticles used as catalyst.

[0087] The balls obtained can also be used as fertilizers if they contain inorganic salts (containing phosphorus, potassium and nitrogen components). These can be salts obtained under subcritical water conditions or under supercritical water conditions (i.e. temperature from 200°C to 1000°C, for example 400°C, and pressure from 50 bar to 1000 bar, for example 250 bar), i.e. precipitated salts from another process.

[0088] The invention also relates to a gasification process comprising a step during which biomass balls as defined above are gasified in a gasification reactor, in particular an entrained flow gasification reactor.

[0089] Biomass pellets can be raw, roasted, pyrolyzed or carbonized.

[0090] The use of such balls facilitates the implementation of the gasification process (and in particular the conveying and injection steps) compared to processes using fine biomass powders or biomass pastes and thus increases the profitability of the gasification process.

[0091] It makes it possible to gasify fine biomass powders (particle size <200 pm) transformed into biomass balls (size between 200 pm and 3 mm, for example) and thus increase profitability since all powders can be gasified.

[0092] The natural binder itself derived from the biomass volatilizes easily in the reactor: the ball can disintegrate over a few seconds in RFE and the fine particles are released and gasified; the binder can itself contribute to the gasification yield.

[0093] In addition, alginate can have an impact on the morphology and structure of the wall of the beads formed, which can promote the penetration of reactive gases during gasification.

[0094] The beads may contain catalysts, which improves yields in thermo-conversion reactors.

[0095] Advantageously, the balls contain less sulfur in proportion to raw biomass powder, which reduces the phenomena of catalyst poisoning during gasification.

[0096] Other characteristics and advantages of the invention will emerge from the additional description which follows.

[0097] It goes without saying that this additional description is given only as an illustration of the subject of the invention and must in no case be interpreted as a limitation of this subject. Brief description of the drawings

[0098] The present invention will be better understood on reading the description of exemplary embodiments given purely for informational purposes and in no way limiting, with reference to the appended drawings in which:

[0099] [Fig.l] represents a protocol for manufacturing biomass balls according to a particular embodiment of the invention.

[0100] [Fig.2] schematically represents a pilot line for the continuous production of balls (capacity: 100 kg / h), according to another particular embodiment of the invention.

[0101] [Fig.3] is a photographic image representing a biochar powder from olive pits.

[0102] [Fig.4] is a photographic image representing wet biomass balls produced from macro-algae and a powder of olive pits roasted at 350°C, according to another particular embodiment of the invention.

[0103] [Fig.5] is a photographic image representing the balls of [Fig.4], after drying.

[0104] [Fig.6] is a photographic image representing beads obtained from the olive stone biochar powder of [Fig.4] and catalysts, according to a particular embodiment of the invention.

[0105] [Fig.7] is a photographic image representing beads obtained from sewage treatment plant sludge, according to a particular embodiment of the invention.

[0106] [Fig.8] is a photographic image representing beads obtained from salts of sludge from a treatment plant, according to a particular embodiment of the invention.

[0107] The different parts represented in the figures are not necessarily on a uniform scale, in order to make the figures more readable.

[0108] The different possibilities (variants and embodiments) must be understood as not being mutually exclusive and can be combined with each other.

[0109] Furthermore, in the following description, terms that depend on the orientation, such as "above", "below", etc. of a device apply with the understanding that the structure is oriented as shown in the figures.

[0110] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0111] Subsequently, even if the description makes particular reference to biomass from the agricultural industry and waste from wastewater treatment plants, the invention is transposable to any material (homogeneous or inhomogeneous) of plant and / or animal origin containing carbon. For example, it may be forestry waste, food waste, household waste, agricultural waste, micro-plastics, nanoparticles, fine particles from industrial processes, carbon black, tire waste, animal bone waste, etc.

[0112] Biomass may also refer to biomass processed by various thermo-conversion processes, such as, for example, torrefaction, pyrolysis, hydrothermal carbonization, hydrothermal liquefaction and gasification and / or carbonaceous residues. For example, the term biomass also refers to biochars (pyrolysis), biocoals (torrefaction), hydrochars (hydrothermal carbonization) and chars (gasification).

[0113] All these resources can be dry or wet.

[0114] The invention is of interest for recovering dust and other small waste (typically particles with dimensions less than 1000 pm, and preferably less than 200 pm), facilitating their storage and their evacuation (e.g.: quenching bath or cyclone in a gasification reactor, sawmills, etc.).

[0115] The process for recovering biomass consists of preparing recoverable particles from, on the one hand, a fine powder of biomass (particle size less than 1000 pm, for example 200 pm) and, on the other hand, algae.

[0116] The biomass treatment process comprises the following steps ([Fig.l]):

[0117] a) providing a first solution containing algae and carbonates,

[0118] b) adding a biomass powder to the first solution, whereby a second solution is formed,

[0119] c) adding dropwise the second solution to an ionotropic coagulation bath comprising divalent ions, whereby biomass beads suitable for use in a gasification process are formed.

[0120] The first solution comprises algae and carbonates.

[0121] The algae can be brown algae, green algae, red algae or microalgae. It can also be a mixture of two or more types of these different algae. For example, it is possible to mix brown algae and red algae or to mix brown algae, red algae and microalgae.

[0122] For example, brown algae are chosen from Sargassum algae (also called Sargasso), Fucus vesiculosus algae (also called Bladderwrack), Laminaria algae, etc. For example, green algae are chosen from Caulerpa taxifolia algae and Codium tomentosum algae. For example, red algae are chosen from Erythrotrichia foliiformis algae and Rhodella algae. For example, microalgae (also called microphytes or microscopic algae) are chosen from Spirulina and Chlorella vulgaris algae.

[0123] Preferably, the algae are brown algae. It may also be a mixture of brown algae and one or more other types of algae. Preferably, the brown algae represent at least 50% by mass of the mixture. The use of brown algae is particularly advantageous, as it ensures a high content of man-nuronic acid and guluronic acid, which are necessary for the formation of alginate.

[0124] The algae are preferably ground in order to facilitate the extraction of the alginate and the formation of beads of homogeneous size and / or homogeneous composition during step c).

[0125] The crushed algae particles preferably have a size of less than 200 pm. The particle size is, for example, between 10 pm and 200 pm.

[0126] The first solution is preferably heated in order to facilitate the formation of the alginate.

[0127] The first solution also comprises carbonates. Preferably, these are sodium carbonates. The first solution may further comprise propionates, for example sodium propionates.

[0128] The first solution is preferably at a temperature between 30 and 60°C, preferably between 30 and 50°C. For example, it is at 45°C. Such temperatures promote the release of alginate from the algae.

[0129] The first solution thus forms an alginate solution, preferably a sodium alginate solution. The mass content of algae in the first solution is, for example, between 0.01% m and 50% m, preferably between 1% m and 10% m.

[0130] The sodium carbonate / algae mass ratio is for example between 1:1 and 1:100, preferably between 1:5 and 1:10.

[0131] The biomass powder provided in step b) comprises biomass particles. The particle size is preferably less than 1000 μm, even more preferably less than 200 μm. The particle size is for example between 100 μm and 1000 μm, preferably between 100 μm and 200 μm and even more preferably between 20 and 50 μm.

[0132] According to a first advantageous variant, the biomass powder is a powder of olive pits, possibly roasted.

[0133] According to another advantageous variant, the biomass powder is formed from sewage treatment plant sludge (also called STEP sludge).

[0134] Step b) is for example carried out with magnetic stirring. The rotation speed of the mixture as well as the duration of the mixing will be chosen by the person skilled in the art. Step b) is carried out until a homogeneous mixture is obtained. A second solution is thus obtained. This solution forms a colloidal suspension.

[0135] In step c), the second solution is injected into an ionotropic coagulation bath (also called a spherification bath). The ionotropic coagulation bath is an aqueous solution. The solution contains multivalent ions (preferably divalent ions) that can react with the alginate to form a polymer. For example, these may be copper, cadmium, barium, calcium, cobalt, nickel, iron, zinc or manganese ions.

[0136] Calcium ions will preferably be chosen. These ions are not toxic and their use does not require an additional purification step compared to other ions.

[0137] The ionotropic coagulation bath is, for example, a solution of calcium chloride and / or calcium nitrate.

[0138] According to another preferred embodiment, the ionotropic coagulation bath contains both calcium ions and potassium ions. Potassium ions have the property of catalyzing the gasification reaction.

[0139] The coagulation bath is, for example, a solution of divalent ion nitrate and / or divalent ion chloride. Different divalent ion nitrates and / or different divalent ion chlorides can be used in the same solution.

[0140] Advantageously, a solution comprising one or more nitrates of divalent ions will be chosen. Many ions can be associated with the nitrates.

[0141] Preferably, the ionotropic coagulation bath is an aqueous solution of calcium nitrate, which may further comprise potassium nitrate.

[0142] Preferably, the ionotropic coagulation bath has a pH between 3 and 7. For example, a pH of 4 will be chosen.

[0143] The ionotropic bath may also comprise substances to give particular properties to the beads, for example colorants, flame inhibiting and / or accelerating agents, etc.

[0144] The ionotropic bath may contain species that chelate multivalent ions, particularly calcium ions.

[0145] The alginate / biomass mass ratio of the colloidal suspension is preferably between 0.01%m and 50%m, preferably between 1%m and 10%m, for example 1%m.

[0146] Step c) is carried out by means of an injection nozzle, preferably having an outlet orifice of 1 mm to 20 mm in diameter. For example, a diameter of 3 mm will be chosen.

[0147] Step d) of drying is advantageously carried out in air at a temperature between 0 and 30°C and preferably at room temperature (typically 20 to 30°C). There is no energy input. Forced air can be used. For example, wet beads 3 mm in diameter have a diameter of 1.45 mm after drying.

[0148] Advantageously, the entire process is carried out at room temperature.

[0149] According to a particularly advantageous embodiment, the process is carried out continuously. For example, the continuous process is carried out using the biomass ball production line shown in [Fig.2]. Such an installation makes it possible to obtain up to 100 kg / h of balls.

[0150] Step a) is carried out in a first reactor 100.

[0151] The first reactor 100 is, for example, a tank with a volume of 100 L. The tank 100 may be provided with an agitator, for example in the form of blades, a level sensor and / or a temperature probe 120 and a heating system 110 for regulating the temperature, for example between 20°C and 100°C. At the bottom of the first reactor 100, a grid may be positioned in order to retain large particles of algae and / or pebbles and grains of sand which may be present in the algae. This prevents clogging of the downstream system. The grid has, for example, 500 μm orifices.

[0152] The biomass powder is prepared and / or stored in a second reactor 200.

[0153] The first reactor and the second reactor are in fluid communication with a mixing tank 300, provided with a mixer 310. Step b) is carried out in the mixing tank 300.

[0154] A peristaltic pump at the outlet of the first reactor 100 makes it possible to control the quantity of algae conveyed into the mixing tank 300 (flow rate for example between 0.1 and 1.0 m3 / h).

[0155] The mixing tank 300 may comprise an agitator (e.g., blades) and / or a level sensor. To continuously adjust the dosage of the biomass powder and the first algae solution, a scale may be used.

[0156] The mixing tank 300 is in fluid communication with one or more injection nozzles 320 arranged opposite a tank 400 containing the ionotropic coagulation bath. Step c) of forming the beads is carried out in the tank 400.

[0157] A flow meter 330 may be used to control the flow rate at the nozzle(s) 320.

[0158] The tank 400 is advantageously provided with a mixing device 410 and / or a pH 420 probe. The pH 420 probe is used to determine whether the quantity of divalent ions is still sufficient.

[0159] The tank 400 may include tappings for taking samples and monitoring the evolution of the pH of the ionotropic coagulation bath. Indeed, during the bead formation process, the concentration of divalent ions decreases. gradually. For example, if the concentration of divalent ions is at least 80% lower than the initial concentration of divalent ions in the bath, the addition of divalent ions will be carried out. Samples from the bath are taken, for example, regularly and analyzed by ion chromatography.

[0160] The balls 10 fall by gravity to the bottom of the tank 400.

[0161] Advantageously, the tank 400 is provided with an outlet 430 arranged opposite a recovery element 500.

[0162] For example, a double guillotine system 440 arranged at the bottom of the tank makes it possible to evacuate a fraction of the volume of the tank 400 formed of a liquid phase 20 and a solid phase (balls 10).

[0163] Alternatively, the ionotropic bath tank may have an upward cascade recirculation system (e.g., comprising two stages), a submersible pump, and / or a channel for guiding the beads formed in the upper stage toward a recovery element 500.

[0164] The recovery element 500 is provided with a multitude of openings. The dimensions of the openings are smaller than the dimensions of the balls 10. The liquid phase passes through the openings. The solid elements (balls 10) are conveyed for example to a drying device 600.

[0165] The recovery element 500 may be an inclined tray or a conveyor belt.

[0166] The drying device 600 operates for example with pulsed air, for example at a temperature below 100°C. For example, we will choose a temperature of 20°C.

[0167] The liquid phase 20 is, advantageously, reinjected into the tank 400.

[0168] A container may be used to collect and store the beads.

[0169] Preferably, the balls thus obtained comprise a homogeneous mixture of the different elements constituting it.

[0170] The balls have a diameter between 1mm and 20mm, for example 3mm.

[0171] The aspect ratio of the ball is advantageously close to 1.

[0172] By aspect ratio close to 1, it is meant that the ratio between the width and the height (or between the largest dimension and the smallest dimension) of the balls formed by this method is close to 1, that is to say that it does not vary by more than 10% and preferably it does not vary by more than 5% compared to the value 1. An aspect ratio close to 1 means that the balls are spherical in shape.

[0173] The balls obtained are rigid materials, stable over time (several years, for example between 1 and 5 years).

[0174] The balls can then be recovered in a gasification process. The biomass powders can be used raw or torrefied in the gasification process.

[0175] The gasification process can be carried out continuously in an installation comprising a gasification reactor, for example with entrained flow, and upstream of this a biomass ball production line intended to implement the biomass treatment process.

[0176] Alternatively, the beads can be used as adsorbent products implemented in various treatments of liquid or gaseous effluents (such as, for example, the removal of H2S from the biomethane production process by anaerobic digestion). In particular, this may involve the treatment of aqueous effluents, for example industrial water. For example, the beads make it possible to adsorb all or part of certain elements present in the aqueous effluents. By way of illustration, lead, zinc or nickel may be mentioned. Water purification processes intended to remove mineral particles contained in polluted water may also be mentioned. After a first step of removing the particles by filtration or centrifugation, the fine particles can be advantageously collected and then removed by the process of the invention.

[0177] The water is thus decontaminated / depolluted.

[0178] The beads may also be used as a catalyst. For example, when the beads contain a catalyst (e.g., nickel, copper, zinc), they may be calcined to form nanoparticles, e.g., nickel oxide, copper oxide, zinc oxide nanoparticles, respectively.

[0179] They can also be used as fertilizers when they contain inorganic salts (for example phosphorus, potassium and / or nitrogen components).

[0180] Illustrative and non-limiting examples of an embodiment:

[0181] Example 1: beads obtained from commercial algae extract and roasted olive kernel powder:

[0182] Step 1): preparation of the SI solution

[0183] In a first reactor, an algae solution is prepared by mixing 1 kg of finely ground algae (particle size less than 200 pm) and 9 kg of water.

[0184] The solution mainly contains brown algae (Sargasso type).

[0185] Then, 0.2 kg of sodium carbonate and 0.05 kg of sodium propionate are added.

[0186] The stirring is mechanical stirring at 300 rpm for 2 h.

[0187] The solution is heated to a temperature below 80°C, for example 45°C, for 8 h.

[0188] Step 2): adding biomass powder to the SI solution

[0189] The biomass powder is prepared in a second reactor. In this example, the biomass particles are olive pit particles (particle size less than 200 pm). The particles were roasted at 350°C ([Fig.3]).

[0190] Such fine particles are particularly difficult to inject into an entrained flow gasification reactor (EFR), due to their poor flowability which causes technical problems of conveying and blocking throughout the system.

[0191] The biomass powder is added to the first solution in a mixing reactor.

[0192] This step is carried out by gravity, or through a peristaltic pump (with a flow rate of e.g. 0.1-1.0 m3 / h). A quantity of biomass powder (1-100 kg) is mixed with the first algae solution (at 300 rpm) for 2 h to form a colloidal solution.

[0193] Step 3): formation of the beads in the ionotropic bath

[0194] An ionotropic bath containing 10 kg of calcium nitrate dissolved in 90 kg of water is prepared.

[0195] The colloidal solution is dosed into the ionotropic coagulation bath by a peristaltic pump (flow rate 0.1-1.0 m3 / h).

[0196] At the pump outlet, a nozzle system (here 3 mm diameter) was installed, which allows the addition of drops of regular size into the ionotropic bath. Beads are obtained ([Fig.4]).

[0197] The desired ball diameter can be adjusted and controlled depending on the nozzle diameter (typically 1 mm to 20 mm, preferably 3 mm).

[0198] The beads formed in the ionotropic bath have a residence time greater than 10 seconds, and less than 5 min ([Fig.4]).

[0199] The ionotropic bath water is recycled through the system through an upward cascade movement and the pH is monitored.

[0200] The initial pH of the bath is greater than pH 3.0 and less than pH 7.0.

[0201] During the bead formation process, the concentration of calcium ions is monitored by taking samples every 4 hours and by analysis using ion chromatography. If, over time, the concentration of calcium ions decreases to a value at least 80% lower than the initial concentration of the bath, the addition of 10 kg of additional calcium nitrate is necessary.

[0202] The average diameter of the balls at the end of the process is 3 mm. However, this diameter can be adjusted and calibrated according to the diameter of the nozzles used.

[0203] Then, the beads are collected and air-dried (at 22°C) for 5 to 10 h. [Fig.5] shows the beads after drying.

[0204] The characterization results of the roasted olive kernel beads and powder are presented in Table 1. Effective analyses Ash content (815^ CalonSw superior power Bonasse c (¾) HS 0' [MJ kg9 Wire powder 6 Ws teéSèe à Ç 76.3 4.43 0.36 8.915 16.8 2.1 29.84 Atgoss extract 34.20 4M thread 43.27 1835 9.97 BÈstes conter®® ia sewing de Royaux 48.98 4.29 091 «LD 37.7 8.95 18.78

[0206] This first example confirms the feasibility of producing beads from biomass and algae extract.

[0207] Example 2: Beads obtained from algae, roasted olive stone powder and catalysts:

[0208] The algae are formed from a mixture of Sargassum and Bladderwrack. For this, 100 mL of Sargassum algae solution was mixed with 300 mL of Bladderwrack algae and mechanically stirred (each algae solution was prepared according to step a) of the process, by adding sodium carbonate). Then 1 g of potassium carbonate was also added to the mixture of algae solutions, to increase the catalytic effect of the final material.

[0209] Into this mixture, the following elements were then added: 3 g of olive kernel powder (particle size less than 200 pm) and 1 g of copper oxide.

[0210] The mixture obtained was mechanically stirred for 1 hour to homogenize the colloidal suspension.

[0211] The ionotropic bath (500g) was prepared from 20g of calcium nitrate and 480g of demineralized water. The colloidal solution was dosed drop by drop. The beads obtained are shown in [Fig.6]. They were characterized. The results are presented in the following table. Elemental analyses Ash content (81 5X) Higher calorific value Brodasse C (%) H Ni (¾) S Si 0 R w (MJ kg-0 Safgassé algae 33.64 4.67 3.94 1.27 3S..52 21.56 12.® Fucus vesicuiosus 36.07 4.7? 3.46 1.77 36 63 1730 14.® Box containing roasted olive oil powder® and catalysts 28.05 3.12 6.54 0.89 43.88 17.52 9.40

[0213] Example 3: Balls obtained from algae and sewage treatment plant sludge (STEP sludge)

[0214] The first solution containing the algae (sargassum and bladderwrack) and the sodium carbonate was prepared as in Example 2.

[0215] To this mixture, 10 g of step mud (containing 50%m of dry matter) was added.

[0216] The algae mixture containing the WWTP sludge was mechanically stirred for 1 hour to homogenize the colloidal suspension.

[0217] The ionotropic bath was prepared as in Example 2.

[0218] The mixture of algae and WWTP sludge was dosed drop by drop as described in Example 1. The beads obtained are shown in [Fig.7]. They were characterized. The results are presented in the following table.

[0219] [Tables3] Elemental analyses Ash content (815 X) Higher calorific value Biwsss CHN (BS 0 (%) (%) W1 Seaweed Sargassum 33 A 4.67 3.94 1.27 35.52 21.56 12.59 Acute Fucus vestotas 36.07 477 3E 177 36.63 17.30 14.35 Balls containing WWTP sludge 25.16 3.69 6.53 1.00 38.48 :25M- 8 85

[0220] Example 4: Balls obtained from algae containing fertilizers (salts obtained from WWTP sludge under supercritical water conditions)

[0221] The separation of salts from the WWTP sludge was carried out under super water conditions critical around 400 °C and 250 bar pressure. These inorganic salts in the form of nano and microparticles were used for the manufacture of beads and their possible use as fertilizer for soil fertilization.

[0222] The composition of the salts obtained is presented in the following table.

[0223] [Tables4] Analysis Unit Concentration C %m on dry 6.0 H on dry 0.51 N %m on dry 0.45 S %m on dry Total aluminum mg / kg dry 38137 total mg / kg dry 77862 Total iron mg / kg dry 52178 Total manganese mg / kg dry 737 Total magnesium mg / kg dry 13823 Total potassium mg / kg dry 11818 Total phosphorus mg / kg dry 108359 Total sodium mg / kg dry 5459 Total calcium mg / kg dry 184370

[0224] The phosphate, potassium and nitrogen content of these salts is very interesting for soil amendment applications. Their mixture with algae contributes to increasing the total nitrogen content by a factor of 10 (from 0.45%m on dry basis to 5.66%m on dry basis) thus facilitating the production of a potential fertilizer formed from balls of calibrated size and easy to transport. The balls obtained are represented in [Fig.8]. The characterization results are presented in the following table. Elemental analyses Ash content (815 Higher calorific value Bmssse î%) HNS 0 W (¾) okr) Seaweed Sargassum 33.04 4.67 3.94 1.27 35.32 21.56 12.59 Acute Fucus vesæatosas 30? 4.77 343 1.77 36.63 17.36 14.35 BSôs containing salts of WWTP sludge 22.64 3.73 5.66 Û 83 39.52 27.62 9.52

[0226] The wet beads were air-dried (without any energy input to the system). The size of the dry beads is 1.6 mm, which is half that of the wet beads.

Claims

Claims

1. A method of treating biomass to produce biomass balls suitable for use in a gasification process, the method comprising the following steps: a) providing a first solution containing algae and carbonates, the first solution preferably being at a temperature of between 30 and 60°C, b) adding a biomass powder to the first solution, whereby a second solution is formed, the particle size of the biomass powder preferably being less than 1000 pm, and even more preferably less than 200 pm, c) adding dropwise, for example by means of an injection nozzle preferably having an outlet orifice of 1 mm to 20 mm in diameter, the second solution to an ionotropic coagulation bath comprising divalent ions, whereby biomass balls suitable for use in a gasification process are formed.

2. A method according to claim 1, characterized in that the ionotropic coagulation bath is an aqueous solution of calcium nitrate or an aqueous solution of calcium nitrate and potassium nitrate.

3. Method according to one of claims 1 and 2, characterized in that the algae are brown algae, optionally mixed with other algae, the brown algae representing at least 50% by mass of the mixture.

4. Method according to claim 3, characterized in that the brown algae are Sargassum algae, Fucus vesiculosus algae or Laminaria algae.

5. Method according to any one of the preceding claims, characterized in that during step a), the first solution comprises sodium carbonates and optionally sodium propionates.

6. Method according to any one of the preceding claims, characterized in that the second solution obtained in step b) comprises copper ions, nickel ions, zinc ions or inorganic salts.

7. Method according to any one of the preceding claims, characterized in that the method comprises a subsequent step d) during which the biomass balls are dried, for example with pulsed air, preferably at a temperature between 0°C and 30°C.

8. A method according to any preceding claim, ca- characterized in that the ionotropic coagulation bath has a pH between 3 and 7.

9. Method according to any one of the preceding claims, characterized in that the algae / biomass mass ratio of the second solution is between 0.0 l% m and 50% m, preferably between 1% m and 10% m, for example 1% m.

10. Method according to any one of the preceding claims, characterized in that the method is carried out continuously, Step a) being carried out in a first reactor (100), The biomass being stored in a second reactor (200), Step b) being carried out in a mixing tank (300), in fluid communication with an injection nozzle (320) arranged opposite a tank (400) containing the ionotropic bath, step c) of forming the biomass balls being carried out in the tank (400) containing the ionotropic bath, the tank (400) being advantageously provided with a pH probe (420), the tank (400) being provided with an outlet (430) arranged opposite an element (500) provided with a multitude of openings, configured to evacuate the balls towards a drying device (600) and making it possible to recover through the openings a liquid phase, the phase liquid being advantageously reinjected into the tank (400).

11. Biomass ball suitable for use in a gasification process and obtained according to the process according to any one of claims 1 to 10, comprising a homogeneous mixture of algae and biomass, the algae preferably being brown algae or a mixture of algae containing at least 50% by mass of brown algae.

12. Biomass ball according to claim 11, characterized in that it further contains a catalyst, preferably a divalent metal, such as nickel, copper, zinc, or in that it further contains inorganic salts.

13. Gasification process comprising a step during which biomass balls as defined in any one of claims 11 and 12 are gasified in a gasification reactor, in particular an entrained flow gasification reactor.