Calcium hydroxide slurry having newtonian rheology

Abstract

The invention relates to a concentrated fine lime milk having Newtonian rheology. The invention also relates to a method of manufacturing a concentrated fine lime milk having Newtonian rheology. The invention relates to the use of said lime milk according to the invention.

Description

[0001] This invention relates to a concentrated lime slurry exhibiting Newtonian or quasi-Newtonian rheological properties. This lime slurry can be used in water treatment and / or sludge treatment, acid waste neutralization, pH adjustment in the chemical and non-ferrous metal industries, papermaking and PCC (precipitated calcium carbonate) industries, and acid flue gas purification. The lime slurry can also be used in civil engineering, construction, or agriculture.

[0002] More specifically, the present invention relates to a lime slurry, in an aqueous phase, comprising a lime particle solid content of 15% by weight or more based on the weight of the lime slurry.

[0003] The present invention also relates to a method for manufacturing concentrated fine lime milk with Newtonian rheological properties.

[0004] This invention relates to the use of the lime milk according to the present invention.

[0005] Highly reactive, concentrated, ready-to-use lime milk or lime slurry (such as Neutralac® SLS45) has become the reagent choice for many applications in the aforementioned industries.

[0006] In addition to high reactivity, high solids content (greater than or equal to 15% by weight), and improved rheological properties, consumers also expect lime slurry to have low viscosity, low settling rate, and extended shelf life, thereby further improving the rheological properties.

[0007] Standard lime slurry, produced by slaking quicklime or pulping "dry" slaked lime powder, is typically high in solids content. The fine particles of standard lime slurry have a solids content of less than 50% by weight, more likely around 30% to 40% by weight, and a reactivity of 3 to 30 seconds. However, they unfortunately have a viscosity of around 300 mPa·s to 1500 mPa·s and settle within a day, resulting in a shortened shelf life.

[0008] Regarding the solids content of lime slurry, high-concentration and ultra-high-concentration suspensions cannot be industrially produced by direct slaking of quicklime because the exothermic reaction of quicklime slaking would cause the suspension to boil, resulting in highly unstable and even dangerous reaction conditions. Conventional cooling is usually ineffective in lowering the reaction temperature below the boiling point. Either the quicklime must be partially pre-hydrated, or it must be mixed with slaked lime (see, for example, WO2016 / 041643 or WO2022 / 234008, in the form of lime slurry or dry slaked lime) to obtain high and / or ultra-high solids content. In practice, this process is rarely used due to its greater complexity compared to slurry preparation.

[0009] For suspensions obtained by slurrying dry lime to achieve high or ultra-high solids content (e.g., 15% by weight or more) and fine particle size, the viscosity tends to be quite high, and this problem is further exacerbated by the shear thinning and thixotropic rheological properties of high-concentration lime slurries. Furthermore, the viscosity of lime slurries is typically unstable, increasing over time. This effect can be so severe that a normally free-flowing lime slurry can become a thick paste within days or even hours. Polymer dispersants (typically polycarboxylate dispersants, particularly polycarboxylate polyether comb copolymer (PCE) dispersants, where the polycarboxylate backbone is typically modified with polyether side chains, forming a comb copolymer structure) are known to reduce viscosity; see, for example, US2014 / 0140907.

[0010] However, these dispersants generally do not prevent viscosity from increasing to a paste-like state over time. To stabilize viscosity changes over time, it is also known to add polyol additives, particularly carbohydrates, including monosaccharides, disaccharides, oligosaccharides and polysaccharides, hydrogenated sugars or sugar alcohols, sugar acids (such as so-called aldonic acids or uronic acids, such as gluconic acid or glucuronic acid or their corresponding salts), or functionalized sugars (such as N-acetylglucosamine or D-glucosamine), which can be added alone (see, for example, WO2007 / 11040) or in combination with polycarboxylate dispersants (see, for example, WO2006 / 050557), thereby providing the additional benefit of reducing viscosity.

[0011] Furthermore, it is known from the prior art, particularly from the document WO2020 / 094607, that a combination of carbohydrate additives (especially sucrose) with polycarboxylate polyether comb copolymer dispersants (such as certain Rheosperse dispersants available from Coatex SAS) can achieve low viscosity and limited viscosity increase over time, even for low-particle-size lime milk, i.e., maintaining low viscosity after 14 days of storage under intermittent stirring (5 minutes / hour).

[0012] In addition, prior art document WO2022 / 234008 discloses a low particle size lime slurry having a combination of carbohydrate stabilizer and polymer dispersant (e.g., Chryso Neomere® Tech 646) with a solid content of 45% by weight. This lime slurry achieves a low viscosity of about 45 mPa·s and remains stable for 28 days (see Example 3).

[0013] Unfortunately, the lime slurry disclosed in the prior art would benefit from improvements.

[0014] Indeed, calcium hydroxide slurry is characterized by its dry solids content (wt%) and fineness (denoted by d). 50 and / or d 98(This refers to the fine particle size distribution). Increasing the dry solids content brings significant economic advantages, especially in terms of transportation and handling costs. Furthermore, the choice of particle size distribution allows for several benefits in industrial applications (rapid dissolution, higher efficiency in certain industrial reactions, and lower sedimentation).

[0015] As mentioned above, when selecting / designing the solids content and particle size distribution, additives / stabilizers must be used to correct the viscosity of the slurry because lime slurry is a non-Newtonian fluid with a variable viscosity that depends on stress. More precisely, calcium hydroxide slurry is a shear-thinning or pseudoplastic fluid, which may also exhibit thixotropy, especially at high solids content and fine particle size. As clearly explained in the cited documents, dispersants / additives / stabilizers improve the dispersion of calcium hydroxide particles and lead to a reduction in viscosity.

[0016] Shear-thinning behavior poses a challenge to handling lime slurry because the higher viscosity (typically orders of magnitude × 10) in the static state forces users / consumers / operators to either maintain constant agitation in the storage container and constant circulation in the metering and dispensing lines, or face very high resistance when restarting the agitation or circulation. This results in a significant increase in power consumption, and excessively large pumps, agitator motors, and similar equipment, leading to higher costs. Despite the high viscosity in the static state, the suspension still readily settles, typically within a day, forming a precipitate with increased solids content, which also increases viscosity. The shear-thinning property further increases the viscosity of this precipitate in the static state, resulting in a pasty precipitate and deposits in poorly agitated sections of transport or storage containers, pipelines, or similar equipment. This thickened deposit hinders operation, causing reduced flow rates or even complete blockages at the outlets of the metering and transfer lines and the transport and storage containers. Unfortunately, cleaning and / or removing these deposits and precipitates is typically cumbersome, requires specialized equipment, and incurs significant costs, necessitating improvements.

[0017] Furthermore, the non-Newtonian rheological properties of conventional lime slurry present significant challenges for operators of storage and metering equipment. For example, lime slurry may often (in a typical storage tank, where the impeller of the agitator is located near the bottom outlet) show no movement on the surface of the lime slurry during agitation. Therefore, it is often difficult, or even impossible, to homogenize the entire tank volume by agitation, or even visually assess whether agitation is sufficient to fluidize the lime slurry for dispensing and batching into the application.

[0018] Another challenge is pumping lime slurry out of the storage tank. Because the product's viscosity is significantly reduced by the pump's shearing action, the viscosity of the lime slurry inside the pump and at its outlet will be much lower than at the inlet. This causes the lime slurry to leave the pump at a faster rate than it enters, posing a risk of cavitation and pump damage.

[0019] As previously explained from the prior art, a conventional solution might be to add large amounts of additives / dispersants / stabilizers, and combinations thereof, to reduce viscosity. However, low-viscosity lime slurry greatly promotes and accelerates sedimentation, making such products difficult to control as maintaining particles in suspension becomes challenging and requires periodic or continuous agitation and homogenization. For example, as disclosed in WO2022 / 234008, a combination of dispersants and carbohydrate stabilizers provides low viscosity, but homogenization is required before measurement. More specifically, homogenization works by remixing the settled / precipitated sediment and also reducing the clarified supernatant to provide a lime slurry homogenized throughout its volume.

[0020] As mentioned above, despite the many advantages of these lime slurries, they require regular mixing or continuous stirring and homogenization, especially when we consider large storage tanks, pumps and transportation solutions for industrial-scale applications.

[0021] Therefore, there is a need to provide a lime slurry that addresses at least some of these drawbacks.

[0022] There is a need to provide a lime slurry that combines the two contradictory and completely opposing performance requirements mentioned above, i.e., a lime slurry having: - Over time, lower and reduced settling significantly reduces the risk of cavitation in the pump and the need for continuous agitation in the tank and circulation in the metering and transfer lines, and promotes / reduces the need for sediment homogenization or cleaning, and - Very low viscosity over time and under pressure, making it easy to manage.

[0023] In addition, there is a need for a high-concentration and fine lime slurry, which, under long-term storage, exhibits at least a reduction in non-uniformity in terms of sedimentation, precipitates, and clarified supernatant, preferably a significant reduction.

[0024] Finally, there is a need to provide a lime slurry that is easy to handle, store, pump, meter, and for emptying and cleaning of tanks and pipelines, so as to save time and costs in the methods of using the lime slurry.

[0025] To address these issues, the present invention provides a lime slurry as described above, the lime slurry comprising at least one polymeric dispersant, wherein the amount of the polymeric dispersant is 1.50% to 3.0% by weight of an active polymeric dispersant relative to the total dry solids content of the lime slurry, wherein the lime slurry, after 28 days, settles less than 5% by weight of bottom solids residue and produces less than 2% by volume of clear supernatant, and wherein the lime slurry, after static storage, has Newtonian rheological properties and a viscosity of less than 200 mPa·s, which is measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with a rotor 62 at a rotational speed of 100 rpm, and the lime slurry exhibits a viscosity of less than 200 mPa·s in 10 s. -1 up to 100 s -1 The viscosity change was less than or greater than 50% within the shear rate range, and this viscosity change was measured using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry.

[0026] According to the present invention, the particle size distribution is measured in terms of volume, for example, d 50 This refers to 50% by volume of particles smaller than this diameter, d 90 This means that 90% by volume of the particles are smaller than this diameter.

[0027] According to the present invention, the Anton Paar MCR102 rheometer uses a cup-cylinder geometry.

[0028] In another embodiment of the invention, the Anton Paar MCR102 rheometer uses a cone-plate geometry or a cup-blade geometry.

[0029] Within the shear rate range (i.e., from 1 s) -1 up to 100 s -1 Viscosity measurements within the range were performed using an Anton Paar MCR102 rheometer, which employs a cone-plate geometry, a cup-cylinder geometry, or a cup-blade geometry.

[0030] Viscosity measurements at 100 rpm were performed using a Brookfield DV-3 rheometer. Rotor 63 was used if the viscosity was >300 cP, and rotor 62 was used if the viscosity was <300 cP.

[0031] According to the present invention, at a liquid height of approximately 18 cm, 1 dm 3 The height of the clarified supernatant was measured on the bottle (and therefore, volume, for a bottle with a constant diameter). It was found that this surprisingly and reasonably corresponds to 1 m of liquid height at approximately 1 m. 3 Clarified supernatant level on IBC.

[0032] It can be seen that the lime milk of the present invention is characterized by the following combination: -Based on the weight of lime slurry, the dry solid content of fine lime particles is greater than or equal to 15% by weight. - Contains at least one polymeric dispersant, wherein the amount of the polymeric dispersant is from 1.50% to 3.0% by weight of an active polymeric dispersant based on the weight of the total dry solids content of the lime slurry. - Preferably, the characteristic diameter d 50 Particle size distribution between 1.0 μm and 3.0 μm, - Preferably, the characteristic diameter d 98 Particle size distribution less than or equal to 20 μm,

[0033] This allows the lime slurry according to the invention to achieve a sedimentation rate of less than 5% by weight of bottom solid residue (sediment) and produce less than 2% by volume of clear supernatant within 28 days.

[0034] Furthermore, and more surprisingly, the inventors have successfully provided a lime milk that, upon standing storage, exhibits Newtonian or quasi-Newtonian rheological properties and a viscosity below 200 mPa·s, measured at room temperature (approximately 20°C) using a Brookfield DV-3 rheometer with a rotor 62 at 100 rpm. This lime milk also exhibits a viscosity below 200 mPa·s in 10 s. -1 up to 100 s -1 The viscosity exhibits a change of less than or at a maximum of 50% within the shear rate range, measured using an Anton-Paar MCR102 rheometer with a cup-cylindrical geometry. This contrasts with the conventional non-Newtonian rheology of lime slurry in the prior art, which varies with time or within 10 s. -1 up to 100 s -1 It exhibits a higher viscosity variation within the shear rate range, specifically exceeding 50% viscosity variation.

[0035] The term Newtonian rheology or quasi-Newtonian rheology is understood in this invention as viscosity being constant relative to shear rate and shear stress (Newtons) or viscosity deviating from shear rate and shear stress (quasi-Newtons) by no more than 50%.

[0036] Therefore, the lime slurry of the present invention has the advantage of having a stable and very low viscosity under static conditions, different stirring and pumping rates, and combined with Newtonian or quasi-Newtonian rheological properties, the lime slurry of the present invention at least greatly reduces or even eliminates the risk of cavitation in pumps, the need for continuous stirring in tanks or circulation in metering and transmission pipelines, and promotes homogenization by tank stirring.

[0037] Furthermore, the lime slurry of the present invention shows that less than 5% by weight of bottom solid residue (sediment) settles out within 28 days and produces less than 2% by volume of clear supernatant (within 28 days). Its advantage is that it can alleviate the problem of sedimentation caused by precipitation, because the viscosity of such sediment will not increase further when left to stand.

[0038] More surprisingly, the inventors have successfully provided a lime slurry of the present invention that possesses Newtonian or quasi-Newtonian rheological properties, such that at least a significant reduction, or even elimination, of the precipitation, settling, or sedimentation of solid residues at the bottom of the lime slurry is achieved. This not only significantly reduces or even eliminates the risk of clogging caused by such sediments, but also minimizes or eliminates the clear supernatant caused by precipitation, and significantly reduces or eliminates the need for homogenization through mixing. This is particularly advantageous when using large quantities of containers, typically industrial bulk containers, IBCs, or tank trucks for transport, for which rehomogenization would be labor-intensive and often difficult due to the need to painstakingly install or remove mixing equipment from each container, unfavorable geometries, and / or the lack of suitable stirring equipment.

[0039] Therefore, the lime slurry according to the present invention also reduces the need for cleaning such deposits and sediments, which significantly saves time and costs.

[0040] Other embodiments of the lime slurry according to the present invention are mentioned below. Preferably, the fine lime particles of the lime slurry of the present invention have a characteristic diameter d. 50 The particle size distribution is within the following ranges: 1.0 μm to 3.0 μm, advantageously 1.0 μm to 2.9 μm, preferably 1.0 μm to 2.8 μm, more preferably 1.0 μm to 2.7 μm, even more preferably 1.0 μm to 2.6 μm, advantageously 1.0 μm to 2.5 μm, more advantageously 1.0 μm to 2.4 μm, even more advantageously 1.0 μm to 2.3 μm, particularly 1.0 μm to 2.2 μm, particularly 1.0 μm to 2.1 μm, even more particularly 1.0 μm to 2.0 μm, for example 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm or 1.9 μm, as determined by laser diffraction (using a Beckman-Coulter LS13). The results were obtained using a 320 device (pretreated with methanol as a carrier solvent and ultrasonic treatment for 4 minutes at 100W).

[0041] In a preferred embodiment, the fine lime particles of the lime slurry according to the invention have a characteristic diameter d.98 The particle size distribution is within the following ranges: less than or equal to 20 μm, advantageously less than or equal to 19 μm, preferably less than or equal to 18 μm, more preferably less than or equal to 17 μm, even more preferably less than or equal to 16 μm, advantageously less than or equal to 15 μm, more advantageously less than or equal to 14 μm, even more advantageously less than or equal to 13 μm, particularly less than or equal to 12 μm, particularly less than or equal to 11 μm, more particularly less than or equal to 10 μm, preferably less than or equal to 9.5 μm, more preferably less than or equal to 9.0 μm, particularly less than or equal to 8.5 μm, less than or equal to 8.0 μm. This particle size distribution was determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with methanol as the carrier solvent at 100W and ultrasonic pretreatment for 4 minutes).

[0042] Preferably, according to the present invention, the characteristic diameter d of the lime particles in the lime milk is determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with methanol as the carrier solvent and ultrasonic dispersion pretreatment at 100 W for 4 minutes). 50 When the lime slurry is greater than or equal to 1.0 μm, the lime particles have a characteristic diameter d. 25 Particle size distribution greater than or equal to 0.4 μm.

[0043] In an advantageous embodiment, the fine lime particles of the lime slurry according to the invention have a solid content of more than or equal to 20% by weight and less than or equal to 70% by weight, particularly more than or equal to 25% by weight and less than or equal to 70% by weight, more particularly more than or equal to 30% by weight and less than or equal to 70% by weight, preferably more than or equal to 35% by weight and less than or equal to 65% by weight, preferably more than or equal to 40% by weight and less than or equal to 60% by weight, even more preferably more than or equal to 40% by weight and less than or equal to 55% by weight, advantageously more than or equal to 40% by weight and less than or equal to 50% by weight, for example 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, and 49% by weight.

[0044] Even more preferably, according to the present invention, at least one polymeric dispersant in the lime milk is a polycarboxylate polyether comb copolymer.

[0045] In a further embodiment, at least one polymeric dispersant in the lime milk according to the invention is preferably a polycarboxylate polyether comb copolymer having a main chain comprising (meth)acrylate units and side chains comprising oxyvinyl or oxypropylene groups.

[0046] In another embodiment, it should be noted that the oxyethylene or oxypropylene groups of the copolymer side chains can be randomly arranged, regularly arranged, or block-arranged. More precisely, one example of the polymer dispersant according to the invention consists of a methacrylic acid monomer and / or any salt thereof, possibly an acrylic acid monomer and / or any salt thereof, or a monomer having the formula (I): R—X—R', wherein: -R indicates a polymerizable unsaturated group, particularly acrylates, methacrylates, urethane methacrylates, vinyl or allyl groups. -R' indicates hydrogen or an alkyl group having 1 to 4 carbon atoms. -X indicates a structure with "n" ethylene oxide EO units and "m" propylene oxide PO units, which can be arranged randomly or regularly. - The above "m" and "n" are two non-zero integers, and are between 1 and 150.

[0047] Therefore, one example of the dispersant copolymer according to the invention has a main chain composed of methacrylic acid monomers and possibly acrylic acid monomers. Preferably, the dispersant copolymer has a main chain composed only of methacrylic acid monomers, or has a main chain composed of methacrylic acid monomers and acrylic acid monomers.

[0048] For example, a suitable polymeric dispersant for lime slurry according to the present invention is Rheosperse 4050 (CoatexSAS).

[0049] In another embodiment, examples of dispersant copolymers according to the invention are disclosed in document FR2776285, which is incorporated herein by reference.

[0050] For example, a suitable polymeric dispersant for lime milk according to the present invention is Neomere® Tech 646 (Chryso SAS).

[0051] Another example of a suitable polymeric dispersant for lime slurry according to the invention is Neomere® Tech757 and / or Neomere® Tech 868 (Chryso SAS).

[0052] Another example of a suitable polymeric dispersant for lime slurry according to the invention comes from the Viscocrete family, more preferably Viscocrete 3027 (SIKA).

[0053] Preferably, the lime particles in the lime slurry according to the present invention have a particle size of <12 μm. 2 / g, preferably <10 m 2 / g, more preferably <9 m 2 / g, Ideally <8 m2 Specific surface area per g (measured using a Micromeritics Tristar apparatus by the BET nitrogen adsorption-desorption method, as described in standard DIN 66134).

[0054] In fact, in a preferred manner, it is difficult to obtain the lime slurry according to the invention that includes the aforementioned advantageous features for lime particles with a high specific surface area.

[0055] The objective of the lime slurry of the present invention, which has specific lime particles (with specific surface areas), is to limit the interactions between neighboring particles, which become more important at higher concentrations. Therefore, if the specific surface area is high, more interactions can occur between the particles because a larger surface area is available for their production, so it is preferable to use lime particles with low specific surface areas.

[0056] Other embodiments of the lime slurry according to the invention are mentioned in the appended claims.

[0057] The present invention also relates to a method for manufacturing lime slurry, comprising the following steps: - Grind lime particles suspended in an aqueous phase, the lime particles having a characteristic diameter d. 98 An initial particle size distribution of less than or equal to 200 μm, preferably less than or equal to 150 μm, and more preferably less than or equal to 100 μm, was determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with ethanol as the carrier solvent at 100W and ultrasonic pretreatment for 4 minutes). - Add a first dose of at least one polymeric dispersant to the aqueous phase, the amount of which is 0.2% to 3.0% by weight of active polymeric dispersant based on the weight of the solid content of the fine lime particles. - Collect lime slurry containing at least 15% by weight of fine lime particles as solids, measured over 28 days. The lime slurry is found to have settled less than 5% by weight of bottom solids and produced less than 2% by volume of supernatant. The lime slurry exhibits Newtonian rheology and a viscosity below 200 mPa·s, measured at room temperature (approximately 20°C) using a Brookfield DV-3 rheometer with a rotor 62 at 100 rpm. The viscosity of the lime slurry is also measured in 10 s. -1 up to 100 s -1 The viscosity change was less than or greater than 50% within the shear rate range, and this viscosity change was measured using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry.

[0058] In a preferred embodiment, the step of grinding lime particles suspended in the aqueous phase is to obtain a product with a characteristic diameter d. 50 Between 1.0 μm and 3.0 μm and with a characteristic diameter d 98 Particle size distribution less than or equal to 20 μm.

[0059] In a preferred embodiment, in the method for manufacturing lime slurry according to the invention, the step of adding the first dose of at least one polymeric dispersant to the aqueous phase is performed before the step of grinding the lime particles.

[0060] Preferably, in the method for manufacturing lime slurry according to the present invention, the step of adding the first dose of at least one polymeric dispersant to the aqueous phase is performed after the step of grinding the lime particles.

[0061] More preferably, in the method for manufacturing lime slurry according to the present invention, the lime particles are dry slaked lime and / or wet slaked lime.

[0062] According to the present invention, the term "the lime particles in the method of producing lime milk according to the present invention are hydrated lime" should be understood as quicklime being hydrated with an excess of water to produce the lime milk.

[0063] Even more preferably, the method for producing lime slurry according to the present invention includes an additional step of concentrating the formed lime slurry before the collection step, preferably by filtration, high-pressure filtration, centrifugation, forced and / or accelerated sedimentation to concentrate the formed lime slurry.

[0064] In another embodiment, the method for producing lime slurry according to the invention includes an additional step of dispersing a second dose of at least one polymeric dispersant in the formed lime slurry, wherein the amount of the polymeric dispersant is 1.0% to 2.8% by weight of an active polymeric dispersant based on the weight of the solid content of the fine lime particles, and this additional step is preferably combined with mechanical stirring.

[0065] In a preferred embodiment of the method for manufacturing lime slurry according to the present invention, the lime particles have a density of <12 μm. 2 / g, preferably <10 m 2 / g, more preferably <9 m 2 / g, Ideally <8 m 2 Specific surface area per g (measured using a Micromeritics Tristar apparatus by the BET nitrogen adsorption-desorption method, as described in standard DIN 66134).

[0066] In a preferred embodiment of the method for manufacturing lime slurry according to the present invention, the fine lime particles of the formed lime slurry have a characteristic diameter d. 50 Between 1.0 μm and 3.0 μm and with a characteristic diameter d 98 Particle size distribution less than or equal to 20 μm.

[0067] Other embodiments of the method for manufacturing lime slurry according to the present invention are mentioned in the appended claims.

[0068] The present invention also relates to the use of the lime slurry of the present invention, or the lime slurry produced by the method according to the present invention, in various applications in water treatment, sludge treatment, acid waste neutralization, pH adjustment and / or solid precipitation in the chemical and non-ferrous metal industries, paper and PCC industries, acid flue gas purification, or construction and agriculture.

[0069] Other embodiments of the use of lime slurry according to the invention are mentioned in the appended claims.

[0070] Other features and advantages of the invention will be apparent from the following non-limiting description and from the examples.

[0071] Example

[0072] The particle size distribution in the following examples and comparative examples was measured using a Beckman-Coulter LS13 320 instrument with ethanol as the carrier solvent and ultrasonic pretreatment at 100W for 4 minutes.

[0073] Example 1 A lime slurry exhibiting Newtonian rheological properties was prepared, with a viscosity of 185 mPa·s. After standing storage (i.e., under unstirred conditions), the lime slurry showed a viscosity of 185 mPa·s. -1 up to 100 s -1 The shear rate variation is less than 50% and measured over 28 days, with less than 5% by weight of bottom solid residue (sediment) settling out and producing 1.3% by volume of clear supernatant (over 28 days).

[0074] A lime slurry was prepared comprising 45.7% by weight of fine lime particles in dry solids based on the weight of the lime slurry, and 1.67% by weight of Neomere® Tech 646 (an active polycarboxylate polyether comb copolymer as an active polymer dispersant) from Chryso relative to the total dry solids content of the lime slurry. The particle size distribution of the lime slurry is as follows: characteristic diameter d 50 It is 1.2 μm, and the characteristic diameter d 98 It is 6.2 μm.

[0075] The preparation of lime milk is as follows:

[0076] 286.4 g of Neomere® Tech 646 dispersant from Chryso (approximately 20% by weight active content) was added to 5000 g of water and dissolved by mixing at 200 rpm using an anchor stirrer. Then 4090 g of dry slaked lime powder (diameter d) was added. 50 It is 6.1 μm in diameter and d in diameter. 98 Its diameter is 77.6 μm, and its specific surface area is 9.7 m². 2 (measured by BET nitrogen adsorption-desorption method using a Micromeritics Tristar apparatus according to DIN 66134), and dispersed by stirring at 300 rpm for 30 min with the same stirrer. After drying to constant weight at 110 °C using a Sartorius infrared thermogravimetric analyzer, the solid content was determined to be 45.7% by weight.

[0077] The resulting suspension was then processed using a Dynomill laboratory rotary bead mill (total chamber volume 1.4 dm³). 3 The rotor speed was 3600 rpm, and yttrium-stabilized zirconia beads with an average diameter of 0.8 mm were used for grinding at a fill level of approximately 75% by volume (relative to the free volume of the grinding chamber) to obtain d 50 It is 1.2 μm and d 98 For a fineness of 6.2 μm, the same equipment and methods as described above were used. The viscosity of the suspension was measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with rotor 63 at a rotational speed of 100 rpm, and the obtained viscosity was 500 mPa·s.

[0078] Add 61.4 g of Neomere® Tech 646 dispersant from Chryso (approximately 20% by weight of active dispersant) to the suspension and stir at 300 rpm for 10 minutes using the anchor stirrer.

[0079] At room temperature of approximately 20°C, using a Brookfield DV-3 rheometer with rotor 62 rotating at 100 rpm, the viscosity of the lime slurry obtained according to the present invention was 185 mPa·s.

[0080] The viscosity and sedimentation of the lime slurry according to the present invention were monitored weekly on samples that had been stored statically for 28 days.

[0081] For viscosity measurements, the sample should be shaken by hand before measurement.

[0082] Viscosity results over 28 days are shown below. Figure 1 .

[0083] Measured using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry, the viscosity was observed to stabilize at approximately 185 mPa·s, and at 10 s⁻¹. -1 up to 100 s -1 The variation within the shear rate range was less than approximately 50%. The sample used for sedimentation testing was not moved, and after 28 days, only 1.3% by volume of clear supernatant was observed at a sample height of approximately 16 cm.

[0084] Example 2 A lime slurry exhibiting Newtonian rheological properties was prepared, with a viscosity of 40 mPa·s and a viscosity that remained constant at 10 s⁻¹. -1 up to 100 s -1 Within the shear rate range, the variation is less than 50%, and measured over 28 days, less than 5.0% by weight of bottom solid residue (sediment) settles out and less than 2.0% by volume of clear supernatant is produced (over 28 days).

[0085] A lime slurry was prepared comprising 45.1% by weight of fine lime particles in dry solids based on the weight of the lime slurry, and 1.52% by weight of Neomere® Tech 646 (an active polycarboxylate polyether comb copolymer as an active polymer dispersant) from Chryso relative to the total dry solids content of the lime slurry. The particle size distribution of the lime slurry is as follows: characteristic diameter d 50 It is 1.3 μm, and the characteristic diameter d 98 It is 6.7 μm.

[0086] The preparation of lime milk is as follows:

[0087] By stirring at 300 rpm for 30 min using the same stirrer as in Example 1, 6 kg of the same dry hydrated lime powder (diameter d) as in Example 1 was mixed. 50 It is 6.1 μm in diameter and d in diameter. 98 The sample (77.6 μm) was dispersed in 24 kg of water to produce a 30 kg suspension. The suspension was dried to constant weight at 110 °C using a Sartorius infrared thermogravimetric analyzer, and the solid content was determined to be 20.9% by weight.

[0088] The resulting suspension is then ground in two steps:

[0089] First, a Dynamill laboratory rotary bead mill (total chamber volume 0.6 dm) was used. 3 The rotor speed was 1200 rpm, using zirconia beads with an average diameter of 1.25 mm (fill level approximately 75% by volume) for grinding, and then at 1.4 dm. 3In the mill, at 2500 rpm, using zirconia beads with an average diameter of 0.8 mm, grinding was performed at a filling level of approximately 75% by volume (relative to the free volume of the mill chamber) to obtain d 50 It is 1.3 μm and d 98 The fineness is 10.2 μm (measured using the same equipment and methods as described above).

[0090] At room temperature of approximately 20°C, the viscosity of the suspension was measured using a Brookfield DV-3 rheometer with rotor 63 at a rotational speed of 100 rpm, and the obtained viscosity was 1370 mPa·s.

[0091] A portion of the suspension was then concentrated to 47% by weight by filtration through a Büchner filter. 259 g of the concentrated suspension was recovered from the filter, and 9.3 g of Neomere®tech 646 dispersant was added. The suspension was then stirred for 1 min using an Ultraturrax T25 rotor-stator-depolymerizer from IKA GmbH. The high-shear treatment of the Ultraturrax device reduced the particle size to d. 50 For 1.3 μm and d 98 The thickness was 6.7 μm. The solid content of the suspension was then adjusted to 45.1% by weight by adding water.

[0092] The viscosity of the lime slurry obtained according to the present invention is about 40 mPa·s (measured at room temperature of about 20°C using a Brookfield DV-3 rheometer with rotor 62 at a rotation speed of 100 rpm). Monitoring for 28 days showed that the lime slurry was stable. No significant amount of clear supernatant was observed during the 28-day period.

[0093] Using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry, at 1 s -1 up to 100 s -1 The viscosity of the lime slurry obtained by this invention was measured within the range of shear rates. It was found that the viscosity of the lime slurry was stable, i.e., it conformed to Newtonian rheological properties, and therefore did not exhibit shear thinning.

[0094] Figure 2 This indicates the change in viscosity of Example 2 over time (28 days) at 100 rpm.

[0095] Figure 3 This shows the relationship between viscosity and shear rate over time in Example 2.

[0096] Figure 4 This shows the relationship between viscosity and shear stress over time in Example 2.

[0097] from Figure 3 "Example 2 - Viscosity and Shear Rate" and Figure 4 As can be seen in “Example 2 - Viscosity and Shear Stress”, a step change in shear rate or shear stress did not lead to a significant difference in viscosity. As those skilled in the art will understand, a viscosity of approximately 20 cP corresponds to a readily flowing liquid, and the observed difference of + / - 3 cP is negligible in practical applications. We also note that a shear rate of 1 sec... -1 The viscosity results at that time were unstable and resulted in significant noise, and did not indicate an increase in viscosity under these conditions. Therefore, the suspension actually behaves as a Newtonian fluid.

[0098] We can also note that, Figure 4 In “Example 2 - Viscosity and Shear Stress”, the dashed curve of shear stress is the curve of the shear rate applied to the sample (this can be found in…). Figure 3 The results (seen in “Example 2 - Viscosity and Shear Rate”) show that shear stress follows the shear rate proportionally and without delay; that is, no shear thinning or time-dependent adaptive effect (thixotropy) was observed – this is the opposite of Comparative Example 1 below. Dynamic viscosity is, of course, derived by dividing the shear stress by the shear rate.

[0099] Comparative Example 1

[0100] 30.7 g of sucrose (crystalline sucrose) was added to 5000 g of water and dissolved by mixing at 200 rpm using an anchor stirrer. Then 4090 g of dry slaked lime powder (d) identical to that in Examples 1 and 2 above was added. 50 It is 6.1 μm, d 98 The sample was 77.6 μm in size and dispersed by stirring at 300 rpm for 30 min using the same stirrer. After drying to constant weight at 110 °C using a Sartorius infrared thermogravimetric analyzer, the solid content was measured to be 45.6% by weight.

[0101] The resulting suspension was then treated with the aforementioned Dynomill 1.4 dm³. 3 Laboratory rotary bead mill (rotor speed 1200 rpm, using zirconia beads with an average diameter of 1.25 mm, and a fill level of approximately 60% by volume (relative to the free volume of the grinding chamber)) was used to grind to obtain d 50 It is 3.5 μm and d 98 For a fineness of 19.3 μm, the same equipment and methods as described above were used. The viscosity of the suspension was measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with rotor 63 at a rotational speed of 100 rpm, and the obtained viscosity was approximately 1000 mPa·s.

[0102] Add 16.4 g of Neomere®tech 646 dispersant to the suspension and stir at 300 rpm for 10 minutes using the anchor stirrer described above. The resulting viscosity was 82 mPa·s - measured using the same equipment and method as described above (at room temperature of approximately 20°C, using a Brookfield DV-3 rheometer with rotor 62 at a rotational speed of 100 rpm).

[0103] Viscosity and sedimentation were monitored weekly on samples that had been stored statically for 28 days.

[0104] For viscosity measurements, the sample should be shaken by hand before measurement.

[0105] The viscosity was observed to increase to 522 mPa·s on the first day and stabilize at approximately 700 mPa·s after about one week. The sample used for sedimentation testing was completely undisturbed, and after 28 days, a clear supernatant of 12% by volume was observed at a sample height of approximately 16 cm.

[0106] Using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry, at 1 s -1 up to 100 s -1 The viscosity of the suspension was measured within a shear rate range. It was found that the viscosity decreased with increasing shear rate and shear stress, a typical characteristic of shear-thinned / pseudoplastic suspensions, such as typical quicklime suspensions / lime slurry according to existing techniques. Although at 60 s... -1 or 100 s -1 At high shear rates, Comparative Example 1 showed a viscosity level similar to that of the suspensions in Examples 1 and 2 (approximately 100 mPa·s @ 100 s⁻¹). -1 ), but in 1 s -1 up to 10 s -1 At low to moderate shear rates, we observed viscosities ranging from hundreds to thousands of mPa·s. This suspension is clearly non-Newtonian, making its handling more challenging than those of Examples 1, 2 (above), and 3 (below).

[0107] Figure 5 This represents the change in viscosity of Comparative Example 1 over time (28 days) at 100 rpm.

[0108] Figure 6 This shows the relationship between the viscosity and the shear rate of Comparative Example 1 over time.

[0109] Figure 7 This shows the relationship between the viscosity of Comparative Example 1 and the shear stress over time.

[0110] exist Figure 7 In “Comparative Example 1 - Viscosity and Shear Stress”, the dashed curve of shear stress is the curve of the shear rate applied to the sample (this can be seen in…). Figure 6 The results (see “Comparative Example 1 - Viscosity and Shear Rate”) show that shear stress follows the shear rate disproportionately. For increasing shear rate steps, the shear stress is initially high, taking 10 to 60 seconds to reach an approximate equilibrium value. For decreasing shear rate steps, the shear stress is initially low, also taking some time to reach equilibrium, and the time to reach equilibrium is similar to that for increasing shear rate (10 to 60 seconds). This also applies to viscosity. We observed not only shear-thinning behavior but also a time-dependent adaptation effect (thixotropy) – both clearly demonstrating the non-Newtonian behavior of the lime slurry according to Comparative Example 1.

[0111] Example 3 A lime slurry exhibiting Newtonian rheological properties was prepared, with a viscosity of 128 mPa·s and a viscosity that remained constant at 10 s⁻¹. -1 up to 100 s -1 The shear rate variation is less than 50% and measured over 28 days, with less than 5.0% by weight of bottom solid residue (sediment) settling out and producing 1.0% by volume of clear supernatant (over 28 days).

[0112] 256 g of the finely ground and filtered concentrated suspension from Example 2, with a concentration of 47% by weight, was recovered from the filter. Instead of Neomere®tech 646, 7.2 g of Rheosperse 4050 dispersant from Coatex SAS (a subsidiary of Arkema SAS) was added to the suspension, and the mixture was stirred at 300 rpm for 10 minutes using the anchor stirrer (representing 2.5% by weight of active dispersant), and the solids content was adjusted to 44.8% by weight – measured using a Sartorius infrared thermogravimetric analyzer. The viscosity obtained was 128 mPa·s, measured using the same equipment and methods as described above (Examples 1 and 2 – measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with rotor 62 at a rotational speed of 100 rpm).

[0113] Viscosity and sedimentation were monitored weekly on samples that had been stored statically for 28 days.

[0114] For viscosity measurements, the sample should be shaken by hand before measurement.

[0115] A slight increase in viscosity was observed overnight to approximately 150 mPa·s, which remained stable at that level with minor fluctuations. The sample used for sedimentation testing was completely undisturbed, and after 28 days, only about 1.0% by volume of clear supernatant was observed at a sample height of approximately 16 cm.

[0116] Figure 8 This indicates the change in viscosity of Example 3 over time (28 days) at 100 rpm.

[0117] Therefore, despite the differences in polycarboxylate ether (PCE) type dispersants from different manufacturers, the behavior of the lime slurry of the present invention according to Example 3 ( Figure 8 It is very similar to Example 2.

[0118] Example 4 A lime slurry exhibiting Newtonian rheological properties was prepared, with a viscosity of 112 mPa·s and a viscosity that remained constant at 10 s⁻¹. -1 up to 100 s -1 Within the shear rate range, the variation is less than 50%, and measured over 28 days, less than 5.0% by weight of bottom solid residue (sediment) settles out and less than 2.0% by volume of clear supernatant is produced (over 28 days).

[0119] A lime slurry was prepared comprising 45.27% by weight of fine lime particles in dry solids, relative to the total dry solids content of the lime slurry, and 2.2% by weight of ViscoCrete® 3027 dispersant (active polycarboxylate polyether comb copolymer as active polymer dispersant) supplied by Sika®. The particle size distribution of the lime slurry is as follows: characteristic diameter d 50 It is 1.2 μm, and the characteristic diameter d 98 It is 8.9 μm.

[0120] The preparation of lime milk is as follows:

[0121] Add 260 g of Viscocrete 3027 dispersant from SIKA GmbH to 4000 g of tap water and dissolve by gentle stirring. Viscocrete 3027 is a clear solution of polycarboxylic acid ether with a solid content of approximately 20% by weight. Add 3273 g of dry slaked lime (its d... 50 It is 9.4 μm, d 98 The diameter is 140 μm, and the surface area of ​​BET is 11.5 m². 2 / g (all measured using the same method as described in Example 1) was dispersed by stirring with an anchor mixer for 30 minutes.

[0122] The obtained suspension was then treated first with an Ultraturrax T65 instrument for 15 seconds to obtain a suspension with a viscosity of 60 mPa·s (measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with rotor 63 at a rotational speed of 100 rpm), and then with Willy A. Bachofen Dynomill 1.4 dm. 3 A laboratory rotary bead mill was used at a rotor speed of 3600 rpm, employing zirconia beads with an average diameter of 0.8 mm, at a fill level of approximately 80% (relative to the free volume of the mill chamber), for 16 dm³. 3 Grinding at a feed rate of / hr to obtain d 50 It is 1.2 μm and d 98 The fineness was 8.9 μm (measured using the same equipment and methods as described above). The solid content of the suspension was 45.27% by weight, measured by drying loss to constant weight at 110 °C using a Sartorius infrared thermogravimetric analyzer.

[0123] Then add 100 g of Viscocrete 3027 dispersant to the suspension and stir at 300 rpm for 10 minutes using the anchor stirrer described above. Using the same equipment and method as above, the obtained viscosity is 112 mPa·s.

[0124] Viscosity and sedimentation were monitored weekly on samples that had been stored statically for 28 days. For viscosity measurements, the samples were shaken by hand before measurement. Viscosity was observed to increase to 173 mPa·s on day 1 and stabilize at approximately 200 mPa·s after about 4 weeks. Samples used for sedimentation tests were completely undisturbed, and after 28 days, a clear supernatant of 1.6% was observed at a sample height of approximately 12.3 cm.

[0125] Using an Anton-Paar MCR102 rheometer with a cone-plate geometry, at 1 s -1 up to 130 s -1 The viscosity of the suspension was measured after 3 days within a shear rate range. Although it was found to decrease with increasing shear rate and shear stress, the decrease was very moderate, especially for shear rates >10 sec. -1 It can be considered quasi-Newtonian because in 10 seconds... -1 up to 130 seconds -1 The viscosity change is only 10 sec within the shear rate range. -1 Approximately 50% of the lower shear rate. At 10 sec -1 At the shear rate, the viscosity is approximately 120 mPa·s, while at 100 sec... -1At this point, the viscosity is 60 mPa·s. As those skilled in the art will confirm, this is only a small difference in viscosity for concentrated and extremely fine lime slurry. From a practical application perspective, this product can be considered to behave as a Newtonian fluid.

[0126] The formulations of this invention were prepared again using polymer dispersants from a different supplier (not Chryso).

[0127] Figure 9 This shows the viscosity of Example 4 as a function of shear rate.

[0128] Figure 10 This shows the relationship between viscosity and shear rate over time in Example 4.

[0129] Figure 11 This shows the relationship between viscosity and shear stress over time in Example 4.

[0130] It should be understood that the present invention is not limited to the described embodiments, and variations may be made without departing from the scope of the claims.

Claims

1. A lime slurry, wherein the lime slurry contains, in an aqueous phase, a fine lime particle solid content of greater than or equal to 15% by weight based on the weight of the lime slurry, the lime slurry comprising at least one polymeric dispersant, wherein the amount of the polymeric dispersant is 1.50% to 3.0% by weight of an active polymeric dispersant relative to the total dry solid content of the lime slurry, wherein the lime slurry is found to have settled less than 5% by weight of bottom solid residue and produced less than 2% by volume of clear supernatant within 28 days, and wherein the lime slurry, after standing storage, has Newtonian rheological properties and a viscosity of less than 200 mPa·s, the viscosity being measured at room temperature of approximately 20°C using a Brookfield DV-3 rheometer with a rotor 62 at a rotational speed of 100 rpm, and the lime slurry having a viscosity of less than 10 mPa·s within 10 s. -1 up to 100 s -1 The viscosity change is less than or maximum of 50% within the shear rate range, and the viscosity change is measured using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry.

2. The lime slurry according to claim 1, wherein the solid content of the fine lime particles is greater than or equal to 20% by weight and less than or equal to 70% by weight, particularly greater than or equal to 25% by weight and less than or equal to 70% by weight, more particularly greater than or equal to 30% by weight and less than or equal to 70% by weight, preferably greater than or equal to 35% by weight and less than or equal to 65% by weight, preferably greater than or equal to 40% by weight and less than or equal to 60% by weight, even more preferably greater than or equal to 40% by weight and less than or equal to 55% by weight, advantageously greater than or equal to 40% by weight and less than or equal to 50% by weight, for example 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, and 49% by weight.

3. The lime milk according to claim 1 or 2, wherein the at least one polymer dispersant is a polycarboxylate polyether comb copolymer, preferably the polycarboxylate polyether comb copolymer has a main chain containing (meth)acrylate units and side chains containing oxyethylene or oxypropylene groups.

4. The lime slurry according to any one of claims 1 to 3, wherein the fine lime particles have a characteristic diameter d. 50 The particle size distribution is within the following ranges: 1.0 μm to 3.0 μm, advantageously 1.0 μm to 2.9 μm, preferably 1.0 μm to 2.8 μm, more preferably 1.0 μm to 2.7 μm, even more preferably 1.0 μm to 2.6 μm, advantageously 1.0 μm to 2.5 μm, more advantageously 1.0 μm to 2.4 μm, even more advantageously 1.0 μm to 2.3 μm, particularly 1.0 μm to 2.2 μm, particularly 1.0 μm to 2.1 μm, and even more particularly 1.0 μm to 2.0 μm. The particle size distribution was determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with methanol as the carrier solvent at 100W and ultrasonic pretreatment for 4 minutes).

5. The lime slurry according to any one of claims 1 to 4, wherein the fine lime particles have a characteristic diameter d. 98 The particle size distribution is within the following ranges: less than or equal to 20 μm, advantageously less than or equal to 19 μm, preferably less than or equal to 18 μm, more preferably less than or equal to 17 μm, even more preferably less than or equal to 16 μm, advantageously less than or equal to 15 μm, more advantageously less than or equal to 14 μm, even more advantageously less than or equal to 13 μm, particularly less than or equal to 12 μm, particularly less than or equal to 11 μm, more particularly less than or equal to 10 μm, preferably less than or equal to 9.5 μm, more preferably less than or equal to 9.0 μm, particularly less than or equal to 8.5 μm, less than or equal to 8.0 μm, and the particle size distribution is determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with methanol as the carrier solvent at 100W and ultrasonic pretreatment for 4 minutes).

6. The lime slurry according to any one of claims 1 to 5, wherein the characteristic diameter d of the fine lime particles in the lime slurry is... 50 When the fine lime particles are greater than or equal to 1.0 μm, they have a characteristic diameter d. 25 Particle size distribution greater than or equal to 0.4 μm.

7. A method for manufacturing lime slurry, comprising the following steps: - Grinding lime particles suspended in an aqueous phase, the lime particles having a characteristic diameter d. 98 An initial particle size distribution of less than or equal to 200 μm, preferably less than or equal to 150 μm, and more preferably less than or equal to 100 μm, wherein the initial particle size distribution is determined by laser diffraction (using a Beckman-Coulter LS13 320 instrument, with ethanol as the carrier solvent at 100W and ultrasonic pretreatment for 4 minutes). - Add a first dose of at least one polymeric dispersant to the aqueous phase, wherein the amount of the polymeric dispersant is 0.2% to 3.0% by weight of an active polymeric dispersant, based on the weight of the solid content of the fine lime particles. - Collect lime slurry containing at least 15% by weight of fine lime particles as solids, measured over 28 days, with less than 5% by weight of bottom solids and less than 2% by volume of supernatant. The lime slurry has Newtonian rheological properties and a viscosity below 200 mPa·s, measured at room temperature (approximately 20°C) using a Brookfield DV-3 rheometer with a rotor 62 at 100 rpm. The viscosity of the lime slurry is measured in 10 s. -1 up to 100 s -1 The viscosity change is less than or maximum of 50% within the shear rate range, and the viscosity change is measured using an Anton-Paar MCR102 rheometer with a cup-cylinder geometry.

8. The method of claim 7, wherein the step of adding the first dose of at least one polymeric dispersant to the aqueous phase is performed prior to the step of grinding the lime particles.

9. The method of claim 7, wherein the step of adding the first dose of at least one polymeric dispersant to the aqueous phase is performed after the step of grinding the lime particles.

10. The method according to any one of claims 7 to 9, wherein the step of grinding lime particles suspended in an aqueous phase is to obtain a material having a characteristic diameter d. 50 Between 1.0 μm and 3.0 μm and with a characteristic diameter d 98 Particle size distribution less than or equal to 20 μm.

11. The method according to any one of claims 7 to 10, wherein the lime particles are dry slaked lime and / or wet slaked lime.

12. The method according to claims 7 to 11, comprising an additional step of concentrating the formed lime slurry prior to the collection step, preferably by filtration, high-pressure filtration, centrifugation, forced and / or accelerated sedimentation to concentrate the formed lime slurry.

13. The method according to any one of claims 7 to 12, wherein the formed lime slurry includes an additional step of dispersing a second dose of at least one polymeric dispersant, wherein the amount of the polymeric dispersant is 1.0% to 2.8% by weight of an active polymeric dispersant based on the weight of the solid content of the fine lime particles, and the additional step is preferably combined with mechanical stirring.

14. The method according to claims 7 to 13, wherein the fine lime particles of the formed lime slurry have a characteristic diameter d. 50 Between 1.0 μm and 3.0 μm and with a characteristic diameter d 98 Particle size distribution less than or equal to 20 μm.

15. Use of the lime slurry according to claims 1 to 6 or the lime slurry produced by the method according to claims 7 to 14 in water treatment, sludge treatment, acid waste neutralization, pH adjustment in the chemical and non-ferrous metal industries, paper and PCC industries, acid flue gas purification, or in the construction and agricultural sectors.

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