Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C19/00—Other disintegrating devices or methods
  • B02C19/16—Mills provided with vibrators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C21/00—Disintegrating plant with or without drying of the material
  • B02C21/007—Disintegrating plant with or without drying of the material using a combination of two or more drum or tube mills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
  • B02C23/06—Selection or use of additives to aid disintegrating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
  • B02C23/08—Separating or sorting of material, associated with crushing or disintegrating
  • B02C23/16—Separating or sorting of material, associated with crushing or disintegrating with separator defining termination of crushing or disintegrating zone, e.g. screen denying egress of oversize material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/34—Other details of the shaped fuels, e.g. briquettes
  • C10L5/36—Shape
  • C10L5/366—Powders
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/40—Solid fuels essentially based on materials of non-mineral origin
  • C10L5/44—Solid fuels essentially based on materials of non-mineral origin on vegetable substances
  • C10L5/447—Carbonized vegetable substances, e.g. charcoal, or produced by hydrothermal carbonization of biomass

Definitions

• the present invention relates to the mechanical treatment of carbonaceous material feedstock and more particularly to a process for the fine grinding of such a feedstock, in particular biomass feedstock.
• fine grinding is understood to mean grinding the particles of the carbonaceous material charge to obtain micron or millimetric dimensions, that is to say up to hundreds of microns or even up to dimensions less than 5 millimeters.
• the crushed carbonaceous material filler particles are smaller in size than the millimetric or micron-sized carbonaceous material filler particles that feed the inlet of the first chamber of the vibratory mill in accordance with the invention.
• a first stage of mechanical treatment is conventionally performed and consists of coarse grinding (shredding for forest chips).
• a second mechanical treatment step subsequent to the first is necessary and consists of fine grinding to confer specific properties on the biomass powder.
• it may be wood flour for the manufacture of biofuels in the form of granules.
• the invention therefore relates more particularly to this second step of mechanical treatment of biomass, for injection in powdered form in a downstream conversion reactor (gasification) or in a combustion or so-called co-combustion reactor (biomass and coal) in a coal-fired power plant or for granulation to produce biofuels.
• the invention is advantageously applied to the gasification of biomass for the production of biofuels from the synthesis gas widely known under the name Syngaz.
• the fine biomass crushing method according to the invention is preferably carried out upstream of a powder conditioning / storage unit itself upstream of a gasification reactor to subsequently produce biofuels.
• the mechanical treatment of biomass typically comprises a first step of coarse grinding, usually at the place of harvest, which in particular facilitates transport and reduce its cost.
• This first step of grinding is carried out by means of shredder (in English "shredder") and leads to centimetric or millimeter-sized particles, typically wood chips in the wood dies. It is made using grinders with proven technology (hammer mill, knife or scissors). The particles thus coarsely ground thus constitute what are called inputs in the gasification or biomass combustion pathways (heat and electricity cogeneration, heat production, biofuel production).
• the size required for the biomass particles is of the order of a few hundred microns.
• the powder obtained with a hammer mill has a more spreading particle size distribution (publication [5]), which is a major drawback for the flowability, that is to say the ability to flow, the powder as highlighted in the publications [6], [7].
• Hammer mill grinding occurs mainly by impact and attrition, which induces an elongated and deformed particle geometry, showing hook-like projections along the fiber, called fibrils, which promote the interlace effect between particles, cohesion between the grains and through this the accentuation of the effect known as the effect of vault in storage containers (silos): see publication [8]. It should also be noted that a longer mechanical treatment induces a high energy cost without fundamentally modifying the shape of the particles, because they always undergo crushing by hammers.
• ball mills conventionally used for grinding coal work by attrition and produce elongated particles and many fines on fibrous materials.
• biomass powders obtained that is to say finely ground
• the biomass powders obtained are difficult to transport, handle, inject into a downstream conversion reactor, because they tend to form agglomerates which generates the effect of arch , poor flowability ...
• the first route consists of a mixed solution of thermal pre-heat treatment called roasting combined with mechanical grinding by the milling technology already proven and mentioned above: hammer mills for fibrous ball mill materials for coal.
• Roasting is a gentle thermal treatment of biomass at the interface between drying and pyrolysis, usually carried out at temperatures between 200 and 350 ° C and aimed at removing water and modifying some of the organic matter bio mass to break its fibers.
• this mild heat treatment alters the fibrous structure of the biomass, thus facilitating its grinding. This makes it possible to reduce the energy cost of grinding and to obtain less fibrous particles, thus easier to transport, store and inject into a downstream reactor: see publication [11].
• the powder obtained for a high roasting of the biomass that is to say leading to a loss of mass greater than 30% by the operation, has characteristics close to those obtained with coal.
• This allows to use the solution conventionally adopted for the grinding and for the powder injection which is the pneumatic conveying (dense phase).
• the intrinsic characteristics of the biomass are at the origin of the difficulties of storage, transport and injection in thermochemical conversion reactors.
• the thermal pre-treatment of roasting solves the problem, but for an energy cost that could prove prohibitive. Evaluations are currently underway.
• the second way is to optimize either grinders given according to the type of biomass or complete chains of mechanical grinding.
• the Esteban team explicitly proposes the serialization of two grinders in order to optimize the energy cost of grinding: see publication [12].
• the choice fell on the implementation of two grinders of the same type, namely hammer mills.
• the authors then worked on the integration of the whole to optimize the energy cost of the chain and the granulometry of the final product. They thus determined the granulometric threshold at the outlet of the first mill, optimized the types of recirculation of the product.
• the authors estimate that the cost of grinding on an industrial scale, that is to say for a flow rate of the order of 10 t / h, amounts to 120 to 150 kWh / t for wood chips (poplar or pine respectively).
• the team of Siyi Luo et al. proposes a grinding chain capable of mechanically treating both wood (pine) and softer biomass (straw, stems ...): see publication [13].
• the proposed chain makes it possible to reduce the dimensions of the particles up to values of 250 ⁇ fixed by a cyclone downstream so that they can be used in a burner. More precisely, the proposed chain comprises two crushers in series, with identical technology called blades (in English "crushers").
• the first mill that is to say the one upstream, has its axis which extends horizontally while the axis of the second mill extends to the vertical.
• the energy cost is estimated at 87 kWh / t for pine chips.
• the general object of the invention is to overcome at least some of the disadvantages of the state of the art of biomass treatment and more generally of carbonaceous material charge for its injection in powder form in a conversion reactor. downstream (gasification) or in a combustion or so-called co-combustion reactor (biomass and coal) in a coal-fired power station or for granulation to produce biofuels.
• a particular aim is to propose a process for the fine grinding of biomass, and more generally of carbonaceous material feedstock, which improves the properties (flowability, fluidization ability) of the powder obtained and at a lower energy cost.
• it is sought according to the particular object to avoid agglomerates of finely ground biomass powder to improve their ability to be transported, manipulated, and injected into a downstream conversion reactor.
• the subject of the invention is a process for the fine grinding of a charge of carbonaceous material according to which the charge of carbonaceous matter, in the form of particles of millimeter or micron dimensions, is introduced at the inlet of a first chamber of vibrating-type mill whose output is connected to the inlet of a second vibrating-type mill chamber, the first and second vibrating mill chambers each comprising grinding bodies freely housed therein and adapted to grind particles, a method according to which the first and second chambers are vibrated so as to crush the particles introduced on the one hand between the grinding body and secondly between them and the peripheral inner wall of each chamber.
• additives of mineral matter and / or additives of vegetable matter and / or additives of material of plant origin are introduced, the additives being in the form of a micron-sized powder.
• micron-sized powder means a powder whose particles have unit dimensions of less than 1 mm with, where appropriate, elementary particles of nanometric size, typically of the order of 100 nm.
• the charge of carbonaceous material is biomass.
• the inventors have thought of putting in series two chambers or stages of vibratory mills, which is advantageous from an energy cost point of view, and to introduce into that the most downstream, that is to say the one in which the biomass particles are already finely ground on the submillimeter scale, additives of mineral matter and / or plant material and / or material of plant origin, in the form of a micron-sized powder, preferably less than 5 ⁇ .
• at least a partial coating of the biomass particles is carried out in the dry process, which makes it possible to improve the flowability properties and the fluidization ability of the powder finally obtained.
• the very fine particles of additives of mineral matter and / or plant material and / or material of plant origin are brought into direct and close contact with the relatively larger biomass particles, by application of mechanical forces. shear and impact for example.
• the additives may be chosen from magnesium stearate (C36H70MgO4), silica in the form of microbeads, such as that marketed under the brand name New reach SilicaFume NR950 and which contains 95% of SiO2 or else marketed by Rhodia under the trade name Tixosil®68 and which contains 90% of the amorphous silica or under the name Tixosil®331.
• the additives may also be based on silicon oxide particles SiO 2 or containing CaCO 3.
• according to the invention is incorporated additives that allow proper operation of a downstream gasification reactor. Thanks to the fine biomass crushing method according to the invention, it is now possible to envisage carrying out, on an industrial scale and continuously, a gravity injection directly in thermo-chemical conversion reactors, which was not envisaged. to date, due to the poor flowability and / or fluidization ability of known biomass powders, with the undesirable vault effect that could occur.
• the mineral composition of the additives is advantageously chosen to be a chemical mineral supplement required for ash management in a downstream gasification reactor. Indeed, it is known that the ash content of the biomass is very variable and of very different composition.
• the publication [15] indicates that wood typically contains 0.5-1% ash with mostly calcium and potassium, whereas wheat straw contains 8% ash with mostly potassium and silica.
• two types of biomass there are significant differences in ash content and very different compositions. These differences directly impact the operation of a gasification reactor: the operation with wood generates a very high ash melting temperature required, which requires the addition of additives (silica in this case) to adjust this temperature to the operation reactor, typically at about 1300-1400 ° C.
• the operation with straw results in a melting temperature required too low for the operation of a gasification reactor requiring the addition of different additives (calcium) to raise this temperature value.
• the micron powder of mineral additives is rich in silicon or calcium (greater than 10% by weight).
• the additive is for example based on particles of silicon oxides SiO 2 or silica-based microbeads.
• the additives making it possible to control the gasification operation are preferably derived from lime, that is to say a mixture of calcium CaCO 3 and magnesium oxide.
• a pre-grinding step is advantageously carried out using a knife mill which produces a powder with particles. shorter (reduced length / diameter ratio) and a reduced fine particle ratio ( ⁇ 30 ⁇ ).
• Particle calibration by sieving also significantly improves the efficiency of fine grinding and particle shaping.
• the sieving operation can be carried out so as to have particles smaller than 500 ⁇ .
• pre-grinding particles of unit dimensions of the order of a millimeter and the vibrating mill is used to adjust the shaping of the particles (remove the fibrils, round the corners and shorten their length).
• the plant material additives are advantageously based on charcoal, such as charcoal and / or cereal straw charcoal.
• the plant material additives may also be advantageously based on roasted biomass, such as roasted wood, or roasted agricultural products, that is to say having previously undergone such as cereal straw, the bark, shells (cherry stones, walnut shells ).
• the amount of added plant material additives is between 0.5 and 20% by weight of the carbonaceous material feed, more preferably between 5 and 10%. It has been found that the greater the quantity of additives added, the better the flowability obtained at the output of the vibratory mill. Thus, the preferred range is advantageous because it is a good compromise between, on the one hand, improving the flowability according to the invention and the cost of carrying out the process.
• the plant material additives may advantageously be based on fossil coal. It is specified here that fossil coal (charcoal) comes from the degradation of the organic organic matter and that it contains minerals whose content may vary according to the geographical area of coal extraction.
• the particle dimensions of the carbonaceous material feed introduced into the first vibrating mill chamber are substantially between 1 and 2 mm.
• the dimensions of the micronic additive powder introduced into the second vibrating mill chamber are substantially less than 5 ⁇ .
• the particle size of the carbonaceous material charge obtained at the outlet of the second vibratory mill chamber is less than 800 ⁇ , preferably less than 200 ⁇ .
• the vibratory mill grinding bodies freely housed inside the chamber consist of several sets of cylindrical bars of unit diameter different from each other.
• the invention also relates to a method for treating biomass in which the mass of biomass is dried in the raw state, and then the fine grinding process as described above is carried out by introducing the biomass into the first vibrating mill chamber. at least dried.
• the dried biomass feed is made with a water content thereof in a range of 10 to 15%.
• a pre-grinding of the dried biomass is carried out upstream of the fine grinding process by introducing it into a chamber of a knife or scissors-type grinder.
• a knife or scissors mill comprises, for example, notches on a central shaft rotatably mounted in the chamber, the notches being adapted to pull the dried biomass particles against the peripheral inner wall of the chamber.
• the particle size of the pre-milled biomass is substantially greater than 1 mm.
• a sieving of the pre-milled biomass is carried out upstream of the fine grinding process, and downstream of the pre-grinding of the dried biomass.
• the sieving of the pre-milled biomass is carried out so as to carry out the fine grinding process from particles of millimeter dimensions less than 2 mm or micron dimensions less than 500 ⁇ .
• the millimeter-sized particles greater than 2 mm are reintroduced into the knife mill.
• the particles obtained are selected according to their dimensions so that they are less than 800 ⁇ , preferably less than 200 ⁇ .
• a roasting heat treatment is carried out with biomass, and then the fine grinding process as described above is carried out by introducing into the first chamber of the vibrating mill the roasted bio mass.
• the subject of the invention is also a continuous bio mass treatment plant intended to implement the method as described above, comprising:
• a micronization mill for grinding additives of mineral material and / or plant material and / or material of plant origin, in the form of a micron-sized powder, the output of the micronization mill being connected to the entrance to the second chamber vibrating mill.
• the plant may further include a drying apparatus upstream of the first vibrating mill chamber. It can also further comprise immediately downstream of the drying apparatus and upstream of the second vibrating mill chamber, a knife mill. It can also further include immediately downstream of the knife mill and immediately upstream of the first vibrating mill chamber, a sieving apparatus. Finally, it may further comprise a dynamic variable speed selector immediately downstream of the second vibrating mill chamber, said dynamic selector being adapted to extract at the output of the second vibrating mill chamber particles smaller than a desired diameter.
• the vibratory mill grinding bodies freely housed inside the chamber advantageously consist of several sets of cylindrical bars of unit diameter different from each other.
• FIG. 1 is a diagrammatic view of a first embodiment of a continuous biomass treatment plant incorporating a vibratory mill with two stages and making it possible to implement the method of fine grinding of the biomass according to FIG. invention;
• FIG. 1A is a schematic view of an alternative embodiment of an installation according to the first illustrated mode of FIG. 1;
• FIG. 2 is a schematic view of a second embodiment of a continuous biomass treatment plant incorporating a vibratory mill with two stages and making it possible to implement the method of fine grinding of the biomass according to FIG. invention
• FIG. 3 is a graph of test records which shows the number of measurements at a given avalanche angle value, the tests being carried out with a wood powder (beech) as a carbonaceous material feedstock of the process fine grinding according to the invention and with or without mineral additives;
• FIG. 4 is a graph of test records which shows the avalanche angle value as a function of the type of wood powder as carbonaceous material feed of the fine grinding process according to the invention and with or without additives of mineral matter;
• FIG. 5 is a graph of test records which shows the number of measurements at a given avalanche angle value, the tests being carried out with a wood meal (sawdust) as a carbonaceous material feedstock of the process fine grinding according to the invention and with or without additives of material of plant origin;
• FIG. 6 is a graph of test records which translates the number of measurements to a given avalanche angle value, the tests being carried out with a wood powder (beech) as a charge of carbonaceous material of the process fine grinding according to the invention and with or without additives of material of plant origin;
• a wood powder beech
• the plant firstly comprises upstream a dryer 1 fed with treated raw biomass to carry out its drying.
• the treated raw biomass consists of forest chips, typically a few mm thick and a few cm in length.
• the flow rate of treated raw mass is of the order of 1 t / h and the dryer 1 used is a rotary kiln dryer, marketed by Maguin.
• This drying step makes it possible to have a reduced energy consumption of the pre-grinding operation immediately downstream on the one hand and allows the optimal operation of the grinding operation according to the invention on the other hand.
• the knife mill 2 may be monorotor type (FL / FNG / FNV) also operating at a rate of 1 t / h and marketed under the trade name Poittemill Forplex. To reduce the energy cost of this pre-grinding operation, care is taken to obtain advantageously at the output of the knife mill particles of dimensions at least equal to one millimeter.
• a sieving operation is carried out continuously using a sieving apparatus 3.
• a sieving apparatus 3 For example, it may be a vibrating sieve marketed by the company RITEC, under the name of MC type.
• the particles of dimensions greater than 2 mm are preferably reinjected into the knife mill 2.
• the fraction thus taken can be used as a fuel for supplying energy to the dryer 1.
• This sieving operation can also be carried out with an apparatus for sieving mesh openings of micrometric (micron) dimensions so as to obtain, at the outlet of the apparatus, micron sized dried biomass particles, typically between 0 and 500 ⁇ . or between 0 and 200 ⁇ .
• fine grinding of the dried, pre-milled and sieved biomass particles is carried out continuously. To do this, these particles are first introduced at the inlet of a first chamber 5 of a vibratory mill. The output of this first vibrating mill chamber 5 is connected directly and immediately downstream to the inlet of a second vibrating mill chamber 7.
• the inlet of the second vibrating mill chamber 7 concomitantly passes biomass particles already finely ground in the first vibrating mill chamber 5, a micron powder of additives 4 (CaCO 3 + SiO 2 or silica microbead ).
• the additives 4 may be continuously micronised to a diameter of less than 20 ⁇ , preferably less than 5 ⁇ by means of a micronization mill 6.
• the first and second chambers, respectively 5 and 7, of vibrating mill can be carried out in the same apparatus.
• it may be the one marketed by the company RITEC under the name Palla 50U (90 kW) which incorporates two grinding stages or in other words two rooms in the same device.
• Palla 50U 90 kW
• steel bodies can be used, preferably in the form of solid cylindrical bars. More preferably, the cylindrical bars used may have a diameter of between 10 and 60 mm, preferably between 20 and 50 mm.
• the grinding bodies can also be in the form of balls or in the form of cylpebs.
• the grinding bodies are of different unit sizes to each other.
• the micronization mill 6 of the additives 4 can also be a vibrating type mill, marketed by the company RITEC, under the name lab / pilot (2.2 kW), and its operating flow can be equal at 10 kg / h.
• Fine grinding according to the invention then advantageously combines the effect of the second chamber 7 vibrating mill and finely milled additives 4 (micron powder). In this way, at least a partial coating of the biomass particles already ground in the first vibratory mill chamber 5 is carried out in a certain way. This improves the flowability and fluidization properties of the powder. At the very least, the vault effect of such a powder conventionally observed in storage silos is considerably reduced.
• the additives 4 have a mineral composition best chosen to control the ash melting temperature in a downstream gasification reactor.
• particles of unit dimensions smaller than 30 ⁇ are extracted using a dynamic selector 6.
• the dynamic selector 6 may be the one marketed by the company RHEWUM under the name of type AQ. This extraction is advantageous because the very fine particles reduce the flow property of the powder.
• This extracted fraction can be used as a combustion product directly in a reactor downstream conversion and / or as a product of combustion directly in the dryer 1 upstream, which further reduces the energy cost.
• the dried, pre-milled, and sieved bio-mass particles are introduced concomitantly with particles of abrasive mineral material 4 'entering the chamber of a vibrating mill 5.
• the fine grinding according to FIG. The invention is thus advantageously supplemented by the effect of the first vibrating mill chamber 5 and the injected inorganic abrasive particles 4 'by coating the biomass particles with the additives.
• the first vibratory mill chamber 5 operates in semi-autogenous operation with the mineral abrasive grinding powder 4 'of particle size equal to 3 mm.
• the mineral abrasive particles 4 'injected are based on SiO 2 silicon oxide particles.
• they have a chemical composition with an SiO 2 content greater than 80%.
• it may be silica (sand) or quartz for example.
• the amount of the abrasive powder 4 ' can be advantageously adjusted with the micronised additive powder 4 injected to have an ash melting temperature adjusted to the operating temperature of the downstream gasification reactor.
• the inlet of the first vibratory mill chamber 5 of the biomass having previously undergone a roasting heat treatment step. It can be forest chips previously shredded to unit sizes of 50 mm and roasted.
• avalanche angle which is a characteristic of a powder flow: the lower the angle, the better the powder flows.
• the avalanche angle of each sample was measured using a device marketed under the name REVOLUTION by MERCURY SCIENTIFIC. This apparatus comprises a drum rotating on itself and inside which the powder is placed whose avalanche angle is to be measured.
• silica additives in the form of microbeads, which is the one marketed by RHODIA under the trademark Tixosil®331.
• FIG. 3 illustrates the number of occurrences (measurements) for a given avalanche angle for the natural beech wood powder respectively without additive, with 1% by mass of Tixosil®331 added and with 2% by mass of Tixosil added ®331. It is clear that the measured average avalanche angle is lower for a larger amount of Tixosil®331 added. In other words, the flowability of the natural beech powder under free flow conditions is improved by the addition of Tixosil®331 mineral additives. This improvement is even greater than the amount of additive is important.
• a third series of tests were also carried out with the same Tixosil®331 mineral additives, but with a spruce wood powder with particle sizes between 0 and 200 ⁇ and for a single batch.
• the graph in Figure 4 illustrates the results obtained for these second and third series of tests: it appears that the avalanche angle measured is lower for a larger quantity of Tixosil®331 added for each batch and whatever the nature of the wood (natural beech or spruce). In other words, the flowability of the wood powder under free flow conditions is improved by the addition of Tixosil®331 mineral additives regardless of the nature (natural beech or spruce) of the wood.
• the improvement in flowability is greater the greater the amount of Tixosil®331 mineral additive.
• an added quantity of Tixosil®331 mineral additives of 2% by weight decreases the value of the avalanche angle by 58 ° (without additive ) at 50 °.
• FIG. 5 illustrates the number of occurrences (measurements) for a given avalanche angle for wood flour (sawdust) with particle sizes between 0 and 200 ⁇ , respectively without additive and with about 10% by weight ( D50%) added fossil coal ("coal"). It is clear that the average avalanche angle measured is lower when fossil coal is added. In other words, the flowability of the wood flour powder in free flow condition is improved by the addition of fossil coal additives.
• FIG. 6 illustrates the number of occurrences (measurements) for a given avalanche angle for natural beech powder of particle sizes between 0 and 200 ⁇ , respectively without additive and with 10% by weight of added coal. wood. It is clear that the average avalanche angle measured is lower when adding charcoal. In other words, the flowability of the natural beech powder under free flow conditions is improved by the addition of charcoal additives.
• the plant can be used for the fine grinding of other charges of carbonaceous material (coal, petcoke ).

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• 2012
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