Classifications

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  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F11/00—Compounds of calcium, strontium, or barium
  • C01F11/02—Oxides or hydroxides
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  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/02—Lime
  • C04B2/04—Slaking
  • C04B2/045—After-treatment of slaked lime
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  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/54—Nitrogen compounds
  • B01D53/56—Nitrogen oxides
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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/68—Halogens or halogen compounds
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  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/041—Oxides or hydroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28004—Sorbent size or size distribution, e.g. particle size
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28011—Other properties, e.g. density, crush strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/28016—Particle form
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28057—Surface area, e.g. B.E.T specific surface area
  • B01J20/28059—Surface area, e.g. B.E.T specific surface area being less than 100 m2/g
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28069—Pore volume, e.g. total pore volume, mesopore volume, micropore volume
  • B01J20/28071—Pore volume, e.g. total pore volume, mesopore volume, micropore volume being less than 0.5 ml/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28078—Pore diameter
  • B01J20/28085—Pore diameter being more than 50 nm, i.e. macropores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/3021—Milling, crushing or grinding
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
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  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/02—Lime
  • C04B2/04—Slaking
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  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/02—Lime
  • C04B2/04—Slaking
  • C04B2/06—Slaking with addition of substances, e.g. hydrophobic agents ; Slaking in the presence of other compounds
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  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/02—Lime
  • C04B2/04—Slaking
  • C04B2/08—Devices therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/40—Alkaline earth metal or magnesium compounds
  • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
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  • B01D2251/604—Hydroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/112—Metals or metal compounds not provided for in B01D2253/104 or B01D2253/106
  • B01D2253/1126—Metal hydrides
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  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
  • B01D2253/304—Linear dimensions, e.g. particle shape, diameter
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
  • B01D2253/306—Surface area, e.g. BET-specific surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2253/308—Pore size
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2253/30—Physical properties of adsorbents
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  • B01D2253/311—Porosity, e.g. pore volume
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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Definitions

• the present invention relates to a method for producing a fine and highly porous powdery lime composition
• a method for producing a fine and highly porous powdery lime composition comprising the steps of introducing quicklime into a feed zone of a hydrator, introducing water into the zone feeding the hydrator, extinguishing said quicklime in an extinguishing zone of the hydrator by means of a quantity of water which is sufficient to obtain a slaked lime having a non-solid residual phase content of between 15 and 15%. % and 55% by weight, preferably between 15 and 35% by weight, drying and grinding said slaked lime to form powdered lime powder composition.
• highly porous powdery lime composition is understood to mean a powdery lime powder composition having a high BET surface area and a high BJH porous volume, which means a BET specific surface area obtained by adsorption of nitrogen greater than or equal to 25 m z / g and a BJH total pore volume consisting of pores with a diameter less than 1000 ⁇ , greater than or equal to 0.15 cm 3 / g.
• powdered lime composition a slaked lime composition consisting of free and individual particles of calcium hydroxide.
• finely powdered powdered lime composition is understood to mean, according to the present invention, a powdered lime powder composition having a particle size d 98 of less than 200 ⁇ , in particular less than 150 ⁇ .
• the powdery lime composition differs in particular granules or pebbles that have a larger particle size.
• Calcium oxide, CaO is often referred to as “quicklime”
• calcium hydroxide, Ca (OH) 2 is referred to as “hydrated lime” or “slaked lime”, both compounds being informally named “lime”.
• lime is an industrial product respectively based on oxide or calcium hydroxide.
• quicklime is meant a mineral solid whose chemical composition is mainly calcium oxide, CaO.
• Quicklime is generally obtained by calcination of limestone (mainly CaCO 3 ).
• the quicklime may also contain impurities such as magnesium oxide, MgO, sulfur oxide, SO 3 , silica, SiO 2 , or alumina, Al 2 O 3 , whose sum is at a rate of a few% by weight.
• the impurities are expressed here in their oxide form, but of course they may appear in different phases.
• Quicklime usually also contains some% by weight of residual limestone, called incinerated residues.
• the quicklime suitable according to the present invention may comprise MgO in an amount ranging from 0.5 to 10% by weight, preferably less than or equal to 5% by weight, more preferably less than or equal to 3% by weight. weight, most preferably less than or equal to 1% by weight relative to the total weight of quicklime.
• quicklime is used in the presence of water.
• Calcium oxide in quicklime reacts rapidly with water to form calcium dihydroxide Ca (OH) 2 , in the form of slaked lime or hydrated lime, in a reaction called hydration or quenching reaction. which is very exothermic.
• the calcium dihydroxide will be simply called calcium hydroxide.
• the slaked lime can therefore contain the same impurities as those of the quicklime from which it is produced.
• the slaked lime according to the present invention may also comprise
• the slaked lime may also comprise calcium oxide, which may not have been fully hydrated during the quenching step, or calcium carbonate CaCO 3 .
• the calcium carbonate can come from the initial limestone (incuit) from which the slaked lime is obtained (via calcium oxide), or from a partial carbonation reaction of the slaked lime by contact with a atmosphere containing C0 2 .
• the amount of calcium oxide in the slaked lime according to the present invention is generally less than or equal to 3% by weight, preferably less than or equal to 2% by weight and more preferably less than or equal to 1% by weight relative to the total weight of the slaked lime.
• the amount of C0 2 in the slaked lime (mainly in the form of
• CaCO 3 is less than or equal to 5% by weight, preferably less than or equal to 3% by weight, more preferably less than or equal to 2% by weight, relative to the total weight of the slaked lime according to the present invention.
• the quenching reaction is generally carried out in a hydrator, in which quicklime is brought upstream of the direction of quenching, i.e. the direction in which the lime is transported along and in the water. hydrator.
• the slaked lime is removed downstream of the direction of extinction.
• Transport means such as a horizontal shaft equipped with mixing blades for example, allow the transport of lime in the direction of extinction in the hydrator, from the supply of quicklime to the withdrawal of the slaked lime.
• the means of transport also allow a homogeneous mixture of lime undergoing hydration and thus improve the contact between water and lime in the hydrator and avoid the formation of hot spots.
• a hydrator can be divided into different consecutive areas.
• the first is called the feed or mixing zone and is the part of the hydrator located upstream of the direction of extinction, in which quicklime and water are introduced and mixed together.
• the second zone called the extinction zone, represents the part of the hydrator in which the quenching reaction occurs mainly, that is to say in which most of the lime is chemically transformed into slaked lime and in which which most of the steam is generated, especially because of this exothermic reaction.
• Different types of hydration and hydration processes exist, depending on the properties of the quicklime used, but also on the expected yield of the quenching reaction and the desired properties of the resulting slaked lime.
• t 6 o is the time required to reach a temperature of 50 ° C. for a water volume of 600 cm 3 initially at 20 ° C, with the addition of 150 g of quicklime.
• the slaked lime compositions are commonly obtained industrially by different processes depending on the amount of water used relative to the lime.
• dry extinction mode water is added to the hydrator in a quantity limited to that which is necessary to completely hydrate the quicklime, taking into account that part will evaporate during the quenching reaction, due to the exothermic nature of this reaction.
• the resultant slaked lime product is a standard slaked lime powder composition having a BET specific surface area generally between 12 and 20 m 2 / g and generally comprising less than 2% by weight. or even less than 1.5% by weight of moisture (free water).
• Standard slaked lime is generally used in a large number of industrial applications such as water treatment, sludge conditioning, flue gas treatment, agriculture, construction, etc.
• the properties of slaked lime are particularly critical for good performance.
• lime is used as a sorbent for a number of gaseous pollutants such as HCl, HF, SO 2, NO x .
• gaseous pollutants such as HCl, HF, SO 2, NO x .
• such lime once it has captured these pollutants, becomes a by-product that needs to be processed or recycled.
• manufacturers are looking for high-performance sorbents to reduce the amount of by-products that are expensive to process.
• One way to increase lime performance is to increase the proportion of hydrated lime that will actually come into contact with the pollutants to be captured, including reducing particle size and / or increasing surface area and / or volume. porous hydrated lime.
• a first approach consists in producing a slaked lime having a high specific surface area, by extinguishing quicklime with an alcohol, especially as described in the document US Pat. No. 5,426,885, or in the presence of particular additives, such as a (di-, tri-) or poly-) ethylene glycol or a (di-, tri- or poly-) ethanolamine, especially as described in WO9209528.
• Another method for the production of slaked lime with a high specific surface area is to extinguish the quicklime with an excess of water so as to obtain, at the exit of the hydrator, a wet slaked lime composition having a moisture content residual between 15 and 35% by weight.
• the wet slaked lime composition is then further dried in a drying device to reduce the moisture content and form a dried dry powdery lime composition.
• This process is generally called "semi-wet process” and is described in particular in WO97 / 14650 and US2894820. More specifically, in WO97 / 14650, in the name of the applicant, the drying step is followed or simultaneously combined with a grinding step so as to control the size of the particles of the slaked lime.
• the resultant powdery lime composition consists essentially of dry calcium hydroxide particles having a residual moisture content of less than 2% by weight of the total composition, a high specific surface area (greater than 30 m 2 / g) with a minimum high pore volume (total pore volume by nitrogen desorption of at least 0.1 cm 3 / g for pores with a diameter less than 1000 Angstroms).
• This lime composition furthermore has an Alpine fluidity of between 40 and 50% and is described as having excellent performance for the treatment of combustion gases in installations comprising a bag filter.
• the document describes manufacturing at the laboratory or pilot scale.
• the insufficient fluidity of the pulverulent lime composition generates a recurring problem of fouling and adhesion phenomena during its production process, its storage, but also during its transportation and its subsequent use, which are responsible additional maintenance resulting in additional costs and lower production efficiency.
• the pulverulent slaked lime composition is handled and transported, in particular by screws, blades or by air in pipes where the particles are distributed in the gas phase. Subsequently, the pulverulent slaked lime composition is generally stored in the compressed state, for example in silos.
• the fluidity of a powdery compound, such as a pulverulent dry lime composition depends on many parameters, some of which are difficult to control. However, a variation in the fluidity of the pulverulent slaked lime composition is unacceptable in an industrial process because it can lead to variations in productivity, but also to unpredictable fouling phenomena in the plant.
• the fluidity characteristics of a powder are, among other things, governed by the size of the particles making up the powder (see the article "Flow properties of powders and bulks solids", Dietmar Schulze http://dietmar-scliulze.de/grdlel .pdf).
• the fluidity of a powder generally decreases when the size (for example the diameter) of the particles constituting the powder decreases.
• the particle size of the powdered lime composition depends on various parameters.
• the first parameter influencing the particle size is the particle size of the quicklime that is used to form the slaked lime.
• the speed of the hydration reaction and the temperature inside the hydrator are also essential factors which govern the hydration reaction and consequently the size of the particles composing the final composition of powdered lime.
• the invention provides a method as mentioned at the beginning characterized in that said drying and grinding steps are simultaneously performed and are a single step of fluidification of the slaked lime to form said thin powdery lime composition. and very porous with Alpine fluidity
• drying and grinding steps being carried out in a mill-dryer selected from the group consisting of a pin mill-dryer, a cage-dryer, an instant dye-deagglomerator and a combination thereof until that the fine and very porous pulverulent slaked lime composition has a non-solid residual phase content, measured by a fire loss test at 180 ° C., of less than or equal to 3.5% by weight, preferably less than or equal to 3% by weight, in particular less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight and greater than or equal to 0.3% by weight, preferably greater than or equal to 0.5% by weight, weight, relative to the total weight of the pulverulent dry lime composition.
• a mill-dryer selected from the group consisting of a pin mill-dryer, a cage-dryer, an instant dye-deagglomerator and a combination thereof until that the fine and very porous pulverulent slaked lime composition has a non-solid residual phase content, measured by a
• Suitable grinding dryers according to the present invention are drying-grinding devices in which the drying and grinding steps are carried out simultaneously and in a time period of between a few seconds and a few minutes (instantaneous mill-grinder).
• the drying-grinding devices according to the present invention differ significantly from devices performing indirect drying, such as a drum dryer, a disk dryer or a blade dryer, vacuum drying, lyophilization or drying in a fluidized bed.
• instantaneous deagglomerator an instantaneous drying device in which there is a rotor or rotating blades at the bottom of the drying chamber which fluidifies the product and creates turbulence in the flow of hot air that penetrates the drying chamber tangentially.
• wet (agglomerated) slaked lime is rapidly dispersed and disintegrated into fine dry particles.
• the resulting fine particles leave the drying chamber from its part while the larger particles remain in the chamber for additional drying and disaggregation.
• Suitable instant deagglomerator according to the present invention include the Anhydro Spin Flash Dryer ® dryer marketed by SPX FLOW, the Drymeister * instant dryer marketed by Hosokawa Micron Group or the Swirl fluidizer TM dryer marketed by GEA Group.
• the process according to the present invention allows the maintenance or even improvement of the sorption properties of the pulverulent dry lime composition while making the process easier.
• a drier-mill selected from the group consisting of a drier-pin mill, a drier-cage mill, an instantaneous dryer-deagglomerator as previously defined does not reduce the porosity characteristics of the slaked lime composition, quite the contrary. It has also been possible, by performing the drying step and the grinding step together, to improve the flow properties of the slaked lime composition while achieving the required fineness.
• a dryer and a grinder are devices that can influence the size distribution, but also the shape of the powdered lime particles and influence, therefore, the fluidity of the powder.
• the internal structure of the powdered quicklime can also be modified and, therefore, the drying step can also damage the porosity characteristics of the powder. Grinding is also a step that may have a negative impact on the porosity characteristics of the powder.
• fluidization step is meant, according to the present invention, a step which makes a powdery composition fluid.
• powdered lime compositions comprising smaller particles have a greater effectiveness of the treatment. More specifically, the treatment of the combustion gases is improved because of a better dispersion of the composition powder in the gas phase (flue gas) and a faster contact between the pollutants and the lime particles of the composition. In addition, the smaller particles have a larger external contact surface, thereby increasing the proportion of hydrated lime that will actually come into contact with the pollutants to be captured.
• the fluidity of a powder generally decreases as the size of the particles making up this powder decreases.
• fluidity sometimes referred to as flowability, is meant in the present invention, the ability of a powder to flow freely, evenly in the form of individual particles.
• the fluidity of the pulverulent slaked lime composition according to the present invention is measured on an Alpine air-jet screening device.
• This Alpine fluidity characterizes the static fluidity of a powder and is determined by the speed of passage of the particles having a diameter of less than 90 micrometers to a sieve of 90 (170 micrometers) by the action of a suction.
• the Alpine fluidity expressed in% corresponds to the ratio between the weight of the fraction less than 90 ⁇ qmu.ia crossed the sieve in 15 seconds (with a depression of 100 mm of liquid density 0.88) and the total weight of the fraction less than 90 ⁇ m. which passed through the sieve after another 2 minutes (with a vacuum of 150 mm of 0.88 density liquid).
• the behavior of a powder in a storage silo can be simulated with another method using a powder rheometer, such as a water flow tester. Brookfield powder (PFT) according to ASTM D6128.
• a powder sample introduced into the equipment is subjected to increasing compaction over time.
• a specific torque is applied to the powder until failure (unconfined failure stress).
• the response of the powder to the applied stress is recorded by a computer, which evaluates the static cohesion of the test sample. The results are expressed by a curve that is compared with AST references.
• the powdered lime composition according to the invention is also characterized by a dynamic fluidity that can be measured by a Granudrum apparatus.
• a certain amount of the powder material is placed in a drum having transparent windows, which is rotated and accelerated in increments of 0 to 20 rpm, and then decelerated in stages.
• the shape of the rotating powder pile (air / powder interface) inside the drum is analyzed by an algorithm.
• a dynamic flow angle and a dynamic cohesion index are determined for each rotational speed.
• the size of the individual particles, as well as the porosity properties of the slaked lime particles are defined by the quenching process.
• the resulting slaked lime particles, at the exit of the hydrator have a water content of 15 to 55% by weight, preferably 15% to 35% by weight, which acts as a binding agent and binds the slaked lime particles together as larger agglomerates.
• non-solid residual phase content of the slaked lime composition is meant the proportion of the non-solid residual phase of the slaked lime composition (i.e. water, such as the free water content, and / or the residual additive content from the process for producing said slaked lime composition, that is to say from additives added before, during or after extinction quick lime) determined by a fire loss test.
• the proportion of the non-solid residual phase of the slaked lime composition i.e. water, such as the free water content, and / or the residual additive content from the process for producing said slaked lime composition, that is to say from additives added before, during or after extinction quick lime
• the fire loss test consists of heating, under atmospheric pressure, about 20 g of the pulverulent slaked lime composition to a predetermined temperature, namely 110 ° C or 180 ° C, and measuring the weight over time of the powder composition using a thermal balance until the weight of the powder does not vary by more than 2 mg for at least 20 seconds.
• a predetermined temperature namely 110 ° C or 180 ° C
• the fire loss test consists of heating, under atmospheric pressure, about 20 g of the pulverulent slaked lime composition to a predetermined temperature, namely 110 ° C or 180 ° C, and measuring the weight over time of the powder composition using a thermal balance until the weight of the powder does not vary by more than 2 mg for at least 20 seconds.
• all the components, in particular the non-solid components, having an evaporation temperature lower than that applied during the test are removed from the powder and their content corresponds, therefore, to the measured weight loss. during the test.
• the non-solid residual phase contains all the non-solid components, in particular the liquid components, together having an evaporating temperature lower than that applied, which will then be removed from the slaked lime composition during the heating process at the same time. predetermined temperature.
• The% by weight of the non-solid residual phase and that of the remaining solid, named dry extract are both calculated according to the weight of the product before and after ignition and are both expressed relative to the weight of the product before the test. fire.
• the result of loss on ignition can therefore vary according to the temperature used during the test. For example, it may be higher at 180 ° C than at 110 ° C if additives are used during or after the quenching process, and if these additives or their derivative phases have an evaporation point greater than 110 ° C and less than 180 ° C, or form with free water an azeotropic substance or an aqueous mixture which evaporates between these temperatures.
• the non-solid residual phase content of the pulverulent slaked lime composition according to the present invention can be measured by a fire loss test at 180 ° C.
• the result of loss on ignition is greater than or equal to 0.3% by weight, preferably greater than or equal to 0.5% by weight and less than or equal to 3.5% by weight, preferably less than or equal to 3% by weight, in particular less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight, and represents the amount of water and / or substances contained therein having a point evaporation less than or equal to 180 ° C.
• the non-solid residual phase content of the pulverulent slaked lime composition according to the present invention may further be measured by a fire loss test at 110 ° C.
• the value of loss on ignition is less than or equal to 3.2% by weight, preferably less than or equal to 2.7% by weight, advantageously less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight, in particular less than or equal to 1.5% by weight and greater than 0% by weight, preferably greater than or equal to 0.2% by weight, advantageously greater than or equal to 0.3% by weight, in particular greater than or equal to 0.5% by weight and mainly represents the amount of water and / or volatile substances contained therein having an evaporation point of less than or equal to 110 ° C , especially water.
• the drying-grinding step is carried out until the pulverulent slaked lime composition has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 180 ° C represents the non-solid residual phase content of the composition of powdered lime measured by a fire loss test at 180 T relative to the weight of the powdered lime composition;
• - LOI 110 ° C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C and is greater than or equal to 2% by weight and less than or equal to 2.5% by weight, relative to the weight of the pulverulent dry lime composition.
• the drying-grinding step is carried out until the pulverulent slaked lime composition has a non-solid residual phase content, measured by a 180 fire loss test.
• C equal to the following formula:
• - LOI 180 ° C represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition;
• - LOI 110 ° C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C and is either less than 0.3% by weight or greater than 2.5% by weight and less than or equal to 3.2% by weight, relative to the weight of the pulverulent dry lime composition.
• the drying-grinding step is carried out until the pulverulent slaked lime composition has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 180 "C represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition;
• - LOI 110 "C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C. and is either less than 0.3% by weight or greater than 2.5% by weight and less than or equal to 3.2% by weight, relative to the weight of the pulverulent dry lime composition.
• the drying-grinding step is carried out until the pulverulent slaked lime composition has a non-solid residual phase content, measured by a 180 fire loss test. ° C, equal to the following formula:
• - LOI 180 oC represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition;
• - LOI 110 ° C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C and is either less than 0.3% by weight or greater than 2.5% by weight and less than or equal to 3.2% by weight, relative to the weight of the pulverulent dry lime composition.
• the drying-grinding step is carried out until the pulverulent slaked lime composition has a non-solid residual phase content, measured by a fire loss test at 110 ° C greater than or equal to 0.3% by weight and less than 2% by weight.
• the slaked lime at the exit of the hydrator may contain a more or less water content.
• the amount of water contained in the slaked lime composition causes the agglomeration of the particles, but also a cohesive composition.
• the quenching process is a semi-wet process, in which quicklime is quenched with a sufficient amount of water to obtain slaked lime.
• the output of the hydrator containing a non-solid residual phase of between 15% and 55% by weight, preferably between 15% and 35% by weight relative to the weight of the slaked lime.
• the water content is reduced by performing a drying step because the final product must be in the form of powder.
• the residual solid phase content contained in the powder and measured by a fire loss test at 180 ° C. must be maintained between 0.3. % by weight and 3.5% by weight relative to the total weight of the pulverulent dry lime composition. If the non-solid residual phase content is reduced below 0.3% by weight, the fluidity of the powder decreases surprisingly and the composition becomes sticky (high adhesion), which is contradictory to the general knowledge of man of the trade in which the non-solid residual phase content of a powder should be reduced as much as possible if a powder having a good fluidity is desired.
• water plays the role of a bonding agent between the particles of the powder which can lead to the agglomeration of these particles and consequently to the formation of cohesive agglomerates.
• it is therefore important to remove the water from the composition in order to disperse and deagglomerate the particles.
• the drier-grinder chosen in the process according to the present invention is capable of removing the water present in the composition and therefore dispersing the particles, it also allows the powder to maintain a good fluidity.
• the method according to the present invention through the use of a specific limited type of mill-dryer under conditions intended to control fineness, fluidity and water content, allows the production of a composition of pulverulent slaked lime very effectively, which is not detrimental to the sorption properties since the porosity properties of the slaked lime composition are maintained and even increased.
• the simultaneous drying and grinding stages make it possible to obtain fine particles, while avoiding fouling and the interruption of the process thanks to improved fluidity.
• the simultaneous drying and milling steps allow better control of the properties of the slaked lime, which are more constant over time from one production to another.
• the reproducible side of the process according to the present invention by making it possible to obtain a high fluidity, despite the fineness of the slaked lime composition, without being detrimental to the porosity characteristic, makes it possible to obtain a very interesting process from one point of view. from the economic point of view since the continuous nature of the process is improved and the prepared product is more constant in terms of quality, which prevents to have to throw certain production not meeting the very high standard of the markets today.
• the combination of an improved control of the fineness and the water content makes it possible to achieve a determined and reproducible quality of the pulverulent slaked lime composition with characteristics of high porosity, as well as a great fluidity.
• BET surface area is meant according to the present invention, the specific surface area measured by nitrogen adsorption manometry at 77 K after vacuum degassing at a temperature of between 150 and 250 ° C., in particular at 190 ° C. C for at least 2 hours and calculated according to the multipoint BET method described in ISO 9277: 2010E.
• the highly porous pulverulent slaked lime composition also has a porous volume BJH total reproducible from one production campaign to another and greater than or equal to 0.15 cm 3 / g, preferably greater than or equal to 0.17 cm 3 / g, advantageously greater than or equal to 0.18 cm 3 / g "more preferably greater than or equal to 0.19 cm 3 / g, in particular greater than or equal to 0.20 cm 3 / g, in particular greater than or equal to 0.21 cm 3 / g and typically less than 0.30 cm 3 / g, in particular lower at 0.28 cm 3 / g.
• porous volume BJH is meant the pore volume as measured by nitrogen adsorption manometry at 77 K after degassing under vacuum at a temperature of between 150 and 250 T, in particular at 190 T during at least 2 hours and calculated according to the BJH method, using the desorption curve.
• total pore volume is meant the pore volume BJH consisting of pores having a diameter of less than 1000 Angstroms.
• the process according to the present invention is further characterized in that the drying and milling step is carried out in a cage dryer-mill, said cage-dryer being composed of one, three or five wheels, such as, but not limited to, a cage dryer-dryer marketed by PSP Engineering or Stedman TM.
• the process according to the present invention is further characterized in that the drying and milling step is carried out in a pin mill-drier, such as, for example, but not limited to an Atritor Dryer-Pulverizer marketed by Atritor Limited.
• a pin mill-drier such as, for example, but not limited to an Atritor Dryer-Pulverizer marketed by Atritor Limited.
• the process according to the present invention is further characterized in that the drying and milling step is carried out in an instantaneous dye-deagglomerator, such as, for example, but not limited to the Anhydro Spin Flash Dryer. * marketed by SPX FLOW, the Drymeister ® instant dryer marketed by Hosokawa Micron Group or the Swirl fluidizer TM dryer marketed by GEA Group.
• a separator may further be advantageously added, above the drying chamber, for better control of the particle size distribution of the resulting dried powdered dry lime composition.
• the process according to the present invention further comprises, before, during and / or after the lime quenching step and / or before, during and / or after the drying and drying step. grinding, a step of adding an additive to quicklime, extinguishing water and / or slaked lime.
• the additive added during the process according to the present invention is diethylene glycol.
• diethylene glycol forms with water a binary aqueous mixture which evaporates at temperatures above 110 ° C.
• the amount of water and the amount of diethylene glycol contained in the powdered quicklime composition can be respectively determined by performing a fire loss test at both 110 ° C, which will substantially indicate the amount of water contained in the pulverulent slaked lime composition, and at 180 ° C, which will substantially indicate the amount of water and diethylene glycol contained in the pulverulent slaked lime composition.
• the amount of diethylene glycol will therefore correspond to the value obtained by subtracting the loss on ignition value obtained at 110 ° C. to the value obtained at 180 ° C.
• the additive added during the process may be an organic additive selected from the group of (mono-) or (poly) ethylene glycol and (mono-) or (poly) ethanolamine, especially triethylene glycol triethanolamine, and mixtures thereof.
• an alkali metal compound selected from the group consisting of hydroxides, carbonates, hydrogenocarbonates, nitrates, alkali metal phosphates, persulfates, and monocarboxylates, such as the alkali metal acetates or formates, and mixtures thereof, in particular those of sodium, potassium and / or lithium and / or calcium stearate, may also be to be added during the process according to the present invention.
• the process according to the present invention is characterized in that the drying-grinding step is carried out until the pulverulent slaked lime composition has an average particle size d 50 of less than or equal to 10 ⁇ , of preferably less than or equal to 8 ⁇ m.
• the notation dx represents a diameter expressed in ⁇ m. measured by laser granulometry in methanol after sonication, with respect to which X% by volume of the particles measured have a smaller or equal size.
• the process according to the present invention is characterized in that the drying-grinding step is carried out until the pulverulent slaked lime composition has a first fraction of particles having a size of less than 32 ⁇ and a second fraction of particles having a size greater than 32 ⁇ provided that the second fraction is less than or equal to 50 percent by weight, preferably less than or equal to 40 percent by weight, advantageously less than or equal to 30 percent by weight, in particular less than or equal to 20 percent by weight, in particular less than or equal to 15 percent by weight, more preferably less than 10 percent by weight, or even less than or equal to 8 percent by weight, relative to the total weight of the composition of powdered lime.
• second fraction of particles larger than 32 ⁇ m Is also expressed by R 32 in the remainder of the specification for the fraction retained at 32 ⁇ m.
• hot air is supplied during the drying-grinding step, at a temperature of between 250 ° C. and 500 ° C., preferably between 350 and 400 ° C. ° C.
• the pulverulent slaked lime composition has, at the exit of the drying-grinding stage, a temperature of between 80 and 150 ° C., preferably between 90 and 130 ° C. vs.
• the temperature of the pulverulent slaked lime composition at the exit of the drying-grinding step can be controlled by adjusting the temperature and / or the volume of the hot air supplied during the drying-grinding step and / or the mass flow rate of wet slaked lime entering the drying-grinding stage.
• the drying-grinding step has a duration of between a few seconds and a few minutes.
• the invention also relates to a fine powdered lime composition
• a fine powdered lime composition comprising slaked lime particles having a BET specific surface area obtained by nitrogen adsorption greater than or equal to 25 m 7 g and a total BJH pore volume equal to or greater than 0.15 cm.
• the composition also has an Alpine fluidity greater than 50%, preferably greater than or equal to 51%, more preferably greater than or equal to 52%, advantageously greater than or equal to 54%, particularly greater than or equal to 55% and said composition mentioned above has a content of non residual solid phase, measured by a test of loss on ignition at 180 ° C, less than or equal to 3.5% by weight, preferably less than or equal to 3% by weight, in particular less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight and greater than or equal to 0.3%, preferably greater than or equal to equal to 0.5% by weight, based on the total weight of the powdered hydrated lime composition.
• an Alpine fluidity greater than 50%, preferably greater than or equal to 51%, more preferably greater than or equal to 52%, advantageously greater than or equal to 54%, particularly greater than or equal to 55%
• said composition mentioned above has a content of non residual solid phase, measured by a test of loss on ignition at 180 ° C, less than or equal to 3.5% by weight
• the slaked lime may contain the same impurities as those of the quicklime from which it is produced, such as magnesium oxide, MgO, sulfur oxide, SO 3 , silica, SiO 2 , or else alumina, Al 2 O 3 , the sum of which is at a level of a few% by weight.
• the impurities are expressed here in their oxide form, but of course they may appear in different phases.
• the slaked lime according to the present invention may comprise magnesium in the form of MgO and / or Mg (OH) 2 , in an amount ranging from 0.5 to 10% by weight, preferably less than or equal to at 5%, more preferably less than or equal to 3% by weight, most preferably less than or equal to 1% by weight, expressed as oxide, relative to the total weight of the slaked lime composition.
• the slaked lime may also comprise calcium oxide, which may not have been fully hydrated during the quenching step, or calcium carbonate CaCO 3 .
• the calcium carbonate can come from the initial limestone (incuite) from which the slaked lime is obtained via the calcium oxide), or from a partial carbonation reaction of the slaked lime by contact with an atmosphere containing C0 2 .
• the amount of calcium oxide in the slaked lime according to the present invention is generally less than or equal to 3% by weight, preferably less than or equal to 2% by weight and more preferably less than or equal to 1% by weight with respect to total weight of the slaked lime.
• the amount of CO 2 in the slaked lime (mainly in the form of CaCO 3 ) according to the present invention is generally less than or equal to 5% by weight, preferably less than or equal to 3% by weight, more preferably less than or equal to 2% by weight, based on the total weight of the slaked lime according to the present invention.
• the quantity of lime available in the powdered lime composition according to the present invention is greater than or equal to 85% by weight, preferably greater than or equal to 87% by weight, preferably greater than or equal to 90% by weight, advantageously greater than or equal to 92% by weight, or even greater than or equal to 95% by weight relative to the dry matter content of the slaked lime composition after LOI at 180 ° C.
• the remaining% by weight consists mainly of calcareous compounds and residues from the non-solid residual phase.
• the available lime content present in the powdered slaked lime composition is determined by placing 0.5 g of powdered slaked lime composition in a sugar solution (15 g of sugar in 150 cm 3 of demineralized water). The sugar solution will dissolve the available lime (i.e., calcium oxide and / or calcium hydroxide) contained in the sample.
• the mixture is stirred for at least 10 to 15 minutes to ensure complete dissolution, and then titrated with a solution of hydrochloric acid (0.5 N HCl), phenolphthalein being used as an indicator.
• the Ca concentration measured by this titration is then expressed as Ca (OH) 2 .
• the pulverulent slaked lime composition according to this invention has a non-residual solid phase content, measured by a test of ignition loss at 110 ° C "exceeding 3.2 % by weight, preferably less than or equal to 2.7% by weight, advantageously less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight, in particular less than or equal to 1.5 % by weight and greater than 0% by weight, preferably greater than or equal to 0.2% by weight, advantageously greater than or equal to 0.3% by weight, in particular greater than or equal to 0.5% by weight .
• the powdered slaked lime composition according to the present invention has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 180 "C represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition;
• - LOI 110 "C represents the non-solid residual phase content of the powdered slaked lime composition measured by a fire-loss test at 110 ° C and is greater than or equal to 2% by weight and less than or equal to 2.5 % by weight, based on the weight of the pulverulent dry lime composition.
• the powdered slaked lime composition according to the present invention has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 110 ° C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C and is either less than 0.3% by weight or greater than 2.5% by weight and less than or equal to 3.2% by weight, relative to the weight of the pulverulent dry lime composition.
• the pulverulent slaked lime composition according to the present invention has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 180 "C represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition;
• - LOI 110 ° C represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C and is either less than 0.3% by weight or greater than 2.5% by weight and less than or equal to 3.2% by weight, relative to the weight of the pulverulent dry lime composition.
• the pulverulent slaked lime composition according to the present invention has a non-solid residual phase content, measured by a fire loss test at 180 ° C, equal to the following formula:
• - LOI 180 "C represents the non-solid residual phase content of the pulverulent dry lime composition measured by a fire loss test at 180 ° C relative to the weight of the pulverulent dry lime composition
• - LOI 110 X represents the non-solid residual phase content of the pulverulent slaked lime composition measured by a fire loss test at 110 ° C. and is either less than 0.3% by weight or greater than 2.5% by weight. weight and lower or equal to 3.2% by weight, relative to the weight of the powdered lime composition
• the powdered lime composition has a residual phase content not solid, measured by a fire loss test at 110 ° C, greater than or equal to 0.3% by weight and less than 2% by weight.
• the pulverulent slaked lime composition according to the present invention has a non-solid residual phase comprising water and / or residual additives (mineral and / or organic), free or bound to the lime compound.
• the slaked lime particles of the pulverulent slaked lime composition according to the present invention have a particle size d 50 of less than or equal to 10 ⁇ , preferably less than or equal to 8 ⁇ , advantageously less than or equal to 7 ⁇ m. in particular less than or equal to 6 microns.
• the notation d x represents a diameter expressed in ⁇ m, measured by laser granulometry in methanol after sonication, with respect to which X% by volume of the particles measured have a smaller or equal size.
• the pulverulent slaked lime composition according to the present invention comprises a first fraction of particles having a size of less than 32 ⁇ m. and a second fraction of particles having a size greater than 32 ⁇ m. provided that the second fraction is less than or equal to 50 percent by weight, preferably less than or equal to 40 percent by weight, advantageously less than or equal to 30 percent by weight, in particular less than or equal to 20 percent by weight, in particular less than or equal to 15 percent by weight, more preferably less than 10 percent by weight, or even less than or equal to 8 percent by weight, relative to the total weight of the pulverulent slaked lime composition.
• the pulverulent slaked lime composition according to the present invention comprises slaked lime particles having a BET specific surface area obtained by nitrogen adsorption greater than or equal to 30 m 7 g, preferably greater than or equal to 32 m 2 / g. advantageously greater than or equal to 35 m 2 / g.
• the slaked lime particles of the pulverulent slaked lime composition according to the present invention have a BET specific surface area obtained by lower nitrogen adsorption.
• the pulverulent slaked lime composition according to the present invention contains slaked lime particles having a total pore volume BJH consisting of pores having a diameter less than 1000 ⁇ , obtained by nitrogen desorption, greater than or equal to 0.17 cm 3 / g, in particular greater than or equal to 0.18 cm 3 / g, preferably greater than or equal to 0.19 cm 3 / g, in particular greater than or equal to 0.20 cm 3 / g, advantageously greater than or equal to 0.21 cmVg.
• the slaked lime particles of the pulverulent slaked lime composition have a pore volume BJH consisting of pores having a diameter less than 1000 ⁇ obtained by nitrogen desorption, less than or equal to 0 30 cm 3 / g, in particular less than 0.28 cm 3 / g.
• the powdered lime composition according to the present invention contains slaked lime particles having a pore volume BJH consisting of pores having a diameter ranging from 100 to 300 ⁇ , obtained by nitrogen desorption, greater than or equal to 0, 07 cm 3 / g, preferably greater than or equal to 0.10 cm 3 / g, advantageously greater than or equal to 0.11 cm 3 / g, in particular greater than or equal to 0.12 cm 3 / g and typically less than 0.15 cm 3 / g, in particular less than 0.14 cm 3 / g.
• the pulverulent slaked lime composition according to the present invention contains particles of slaked lime having a porous volume.
• the powdery lime composition according to the invention also has an alkaline phase characterized by an alkali metal content greater than or equal to 0.2% by weight and less than or equal to 3.5% by weight relative to the total weight of the pulverulent dry lime composition.
• the alkaline phase may be in ionic form or in bound form.
• Different types of salts may be added during the process, in particular an alkali metal compound selected from the group consisting of alkali metal hydroxides, carbonates, hydrogencarbonates, nitrates, phosphates, persuadates and monocarboxylates, such as as acetates or formates of alkali metals and mixtures thereof, in particular those of sodium, potassium and / or lithium.
• the powdered lime powder composition according to the present invention further contains calcium stearate.
• the pulverulent slaked lime composition is preferably obtained by the process according to the present invention.
• the invention also relates to an industrial sorbent composition comprising at least said powdered lime powder composition according to the invention.
• the invention also relates to the use of the pulverulent dry lime composition according to the present invention for purifying combustion gases.
• the pulverulent slaked lime composition according to the present invention is used in a dry injection of sorbent.
• the pulverulent slaked lime composition according to the present invention is used for the capture of acid pollutants from the combustion gases, such as HCl, HF, SO ", NO".
• the pulverulent slaked lime composition according to the present invention is used in an industrial sorbent composition, for example in combination with at least one other generally known sorbent for the treatment of combustion gases, such as a sorbent selected from the list of compounds organic compounds, in particular activated charcoal, lignite coke and mixtures thereof, and inorganic compounds, in particular inorganic compounds known to capture dioxins, furans and / or heavy metals, such as halloysite, sepiolite, bentonite or any sorbent described in the application DE4034417.
• a sorbent selected from the list of compounds organic compounds, in particular activated charcoal, lignite coke and mixtures thereof
• inorganic compounds in particular inorganic compounds known to capture dioxins, furans and / or heavy metals, such as halloysite, sepiolite, bentonite or any sorbent described in the application DE4034417.
• Other embodiments of the use according to the invention are mentioned in the appended claims.
• FIG. 1 shows a schematic diagram of FIG. an installation for the preparation of a highly porous powdery lime composition according to the present invention.
• the device shown in FIG. 1 comprises an extinguishing unit, also called hydrator 1.
• This hydrator 1 is fed with quicklime via a feed pipe 2 and with water through the water. 3. If an additive is used in the preparation of the absorbent, said additive is fed through at least one feed line 4.
• said additive is first dissolved in a reservoir (not shown), from which it is pumped by means of a pump (not shown) and added to the water supply line. extinguishing 3 before entering the hydrator 1.
• the additive can also be added directly into the hydrator 1.
• the additive may also be added to the quicklime before extinction.
• the additive can also be added after the hydrator, namely before the drier-mill, but also in the drier-mill or after the drier-mill.
• the non-solid residual phase content of the product is measured continuously by an infrared device 5.
• This non-solid residual phase content is generally greater than 20% by weight.
• the product, wet slaked lime, is transferred to a drier-mill which is supplied with hot air at about 400 ° C, by via the supply line 7, which makes it possible to deagglomerate and dry the product.
• the final product is then separated from the drying air stream in a bag filter 8, then directed to a storage silo 9.
• the production plant according to the present invention is characterized in that the mill-drier 8 is selected from the group consisting of a drier-pin mill, a caged mill dryer, an instant deagglomerator deagglomerator.
• the BET surface area is determined by nitrogen adsorption manometry at 77 K after vacuum degassing at a temperature between 150 and 250 ° C., especially at 190 ° C. for at least 2 hours and calculated according to the multipoint BET method described in ISO 9277: 2010E
• the porous volume BJH is measured by manometry with nitrogen adsorption at
• the total pore volume corresponds to the pore volume BJH composed of pores having a diameter of less than 1000 Angstroms.
• the notation d x represents a diameter expressed in ⁇ , measured by laser granulometry in methanol after sonication, with respect to which X% by volume of the particles measured have a smaller or equal size.
• the fire loss test is carried out according to the procedure described above.
• the Alpine fluidity is measured on about 50 g of the powder sample, according to the procedure described above.
• a very porous pulverulent hydrated lime with a high fluidity according to the invention is produced industrially by mixing water and quicklime in a hydrator (4.5 t / h of quicklime), in such quantities that the product comes out of the hydrator with a non-solid residual phase content, measured by a fire loss test at 180 ° C, of 23 to 24% by weight.
• This moist hydrated lime is then transported and arrives in a drier-pin mill (Atritor Dryer-Pulverizer marketed by Atritor Limited) in which hot air is injected (about 20000 Nm 3 / h, 370 ° C). In this drier-pin mill, the product is deagglomerated and dried simultaneously.
• the slaked lime product is separated from the air by a bag filter.
• a solution of 100% DEG is sprayed through an atomizing nozzle into the duct to create a mist of DEG through which the slaked lime particles must pass. In this way, a good contact between the particles and the droplets of DEG is ensured, which produces a homogeneous product.
• the amount of DEG corresponds to 0.3% by weight of the pulverulent dry lime composition.
• This resultant powdery lime slurry composition has an Alpine fluidity of 57% and a non-solid residual phase content of 0.5% by weight, when measured by a 180 ° C loss-to-fire test, and 0% by weight. , 3% by weight when measured by a fire loss test at 110 ° C.
• the composition of powdered lime has a d 50 of 5 ⁇ and a fraction of particles with a size greater than 32 ⁇ of 10% by weight. Its BET specific surface area and its total pore volume are respectively 44.1 m 2 / g and 0.240 cm 3 / g
• a highly porous powdery lime composition with a high fluidity according to the invention is industrially produced by mixing water and quicklime in a hydrator (6 t / h of quicklime), in such quantities that the product comes out of the hydrator with a content of non residual solid phase ", as measured by a test of loss on ignition at 180 ° C, between 17.4 and 21% by weight.
• This moist hydrated lime is then transported and arrives in a cage grinder-dryer (commercially available from PSP Engineering) wherein hot air is injected (12 500 Nm 3 / h, 370 and 400 * C). The drying can therefore again be regarded as instantaneous and the product leaves the dryer-cage mill at a temperature close to 120 to 125 ° C.
• the cage mill consists of 5 concentric wheels, 2 static wheels and the 3 others are in rotation (speed of rotation up to 900 rpm).
• the slaked lime product is separated from the air by a bag filter.
• a very small amount ⁇ 0.1% by weight, expressed as% by weight of quicklime
• the resulting powdery lime powder composition has an Alpine fluidity of 60% and a non-solid residual phase content when measured by a fire loss test at 180 ° C of 0.5% by weight.
• the composition of powdered lime has a d 3 ⁇ 4 of 5 ⁇ and a fraction of particles with a size greater than 32 ⁇ of 46% by weight. Its specific surface area and its total pore volume are respectively
• a very porous pulverulent lime composition with a high fluidity according to the present invention is produced industrially by mixing water and quicklime in a hydrator (6.8 t / h of quicklime), in such quantities that the product out of the hydrator with a non-solid residual phase content, measured by a fire loss test at 180 ° C, of between 23 and 25% by weight.
• This moist hydrated lime is then transported and arrives in a cage-dryer (marketed by Stedman TM) in which hot air is injected (23,600 Nm 3 / h, 260 to 290 ° C).
• the cage mill consists of 3 concentric wheels (rotation speed close to 520 rpm under standard conditions).
• the slaked lime product is separated from the air by a bag filter.
• DEG expressed as% by weight of quicklime
• the resulting powdery lime composition has an Alpine fluidity of 52.3% and a non-solid residual phase content of 0.7% by weight when measured by a 180 ° C loss-to-fire test, and 0.4% by weight when measured by a fire loss test at 110 ° C.
• the pulverulent dry lime composition has a d 50 of 9.3 ⁇ and a fraction of particles greater than 32 ⁇ by 34.3% by weight. Its specific surface and its total pore volume are
• a highly porous powdery lime composition is produced industrially by mixing water and quicklime (2.7 t / h of quicklime) in a hydrator, in such quantities that the product leaves the hydrator with a content non-solid residual phase, measured by a fire loss test (LOI) at 180 ° C, of between 22 and 24% by weight. 0.2% DEG (expressed as a% of the weight of quicklime) is added to the extinguishing water before hydration.
• LOI fire loss test
• the wet slaked lime that comes out of the hydrator is then transported to a drier-broveur pin (Atritor Dryer-Pulverizer marketed by Atritor Limited) into which hot air is injected to instantly dry the wet slaked lime and to produce the highly porous powdery lime composition before storing it in a storage area.
• a drier-broveur pin (Atritor Dryer-Pulverizer marketed by Atritor Limited) into which hot air is injected to instantly dry the wet slaked lime and to produce the highly porous powdery lime composition before storing it in a storage area.
• the resulting totally dried quenched lime is mixed with various given amounts of water and / or diethylene glycol (DEG).
• DEG diethylene glycol
• the mixing is carried out by adding water and / or DEG dropwise to the fully dried slaked lime which is stirred in an intensive laboratory mixer (Eirich ELI).
• Eirich ELI intensive laboratory mixer
• the non-solid residual phase measured by LOI at 180 ° C following the procedure described above, is a good indicator of the sum of water and DEG added in the laboratory to lime. extinguished totally dried since the variation, which is the difference between the theoretical value and the measured value, is less than ⁇ 0.20%, most of the time less than ⁇ 0.10%.
• the following example is carried out in order to evaluate the influence of the non-solid residual phase content, in particular of the water content and / or DEG of the pulverulent slaked lime composition, on its fluidity, all the other parameters. being fixed, such as particle size, particle shape, chemical composition, surface area and pore volume of the slaked lime composition.
• Example 5 The same procedure as in Example 5 is followed, except that the water content is changed. The results are shown in Tables 4 and 5.
• Example 6 The same procedure as in Example 5 is followed except that different amounts of water and DEG are added to the totally dried slaked lime with the same process as that described in Example 4. The results are mentioned in table 6.

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• 2017
  • 2017-06-23 EP EP17732130.4A patent/EP3475227A1/de not_active Withdrawn
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