LOW VISCOSITY MILK OF LIME

Abstract

Low viscosity milk of lime comprising fine lime particles in suspension in an aqueous phase containing at least a first polymer dispersant and a second dispersant being either sodium gluconate or gluconic acid, mixture of sugar containing at least glucose and fructose, said low viscosity milk of lime showing a stable viscosity over 28 days lower than or equal to 600 mPa.Math.s, preferably equal to or lower than 300 mPa.Math.s.

Claims

1. Low viscosity milk of lime comprising fine lime particles in suspension in an aqueous phase containing at least a first dispersant and a second dispersant, said fine lime particles having a particle size distribution with a characteristic diameter d.sub.25 equal to or lower than 2 ?m as measured by laser diffraction with methanol as carrier solvent, said milk of lime containing a fine lime particles content comprised between 30 and 75 wt %, wherein the first dispersant is a dispersant polymer present at an amount of 0.03 to 0.24 wt % non-volatile matter, with respect to the solid matter content of the low viscosity milk of lime, and wherein the second dispersant is present at an amount of 0.10 to 1.0 wt % non-volatile matter with respect to the total weight of the low viscosity milk of lime and comprises either (i) sodium gluconate or gluconic acid, (ii) a mixture of sugar containing at least glucose and fructose, (iii) xylitol, wherein said first dispersant and said second dispersant are present together at an amount comprised between 0.11 and 1.15 wt % non-volatile matter with respect to the total weight of the low viscosity milk of lime, said low viscosity milk of lime showing a stable viscosity over 28 days lower than or equal to 600 mPa.Math.s, as measured by a Brookfield DV III Rheometer, with the suitable spindle according to the observed torque or viscosity, typically LV spindle No 3. at 100 rpm with the measurement taken on the 30th second after the rheometer motor was turned on.

2. Low viscosity milk of lime according to claim 1, wherein fine lime particles have a particle size distribution with a characteristic diameter d.sub.50 lower than or equal to 4 ?m as measured by laser diffraction with methanol as carrier solvent.

3. Low viscosity milk of lime according to claim 1, wherein fine lime particles have a particle size distribution with a characteristic diameter doo lower than or equal to 15 ?m as measured by laser diffraction with methanol as carrier solvent.

4. Low viscosity milk of lime according to claim 1, wherein fine lime particles have a particle size distribution with a characteristic diameter d.sub.98 lower than or equal to 90 ?m measured by laser diffraction with methanol as carrier solvent.

5. Low viscosity milk of lime according to claim 1, wherein said fine lime particles have a specific surface area measured by nitrogen adsorption manometry and calculated according to the BET (Brunauer, Emmett et Teller) method lower than or equal to 12 m.sup.2/g.

6. Low viscosity milk of lime according to claim 1, having a density comprised between 1.3 kg/dm.sup.3 and 1.4 kg/dm.sup.3.

7. Low viscosity milk of lime according to claim 1, wherein said first dispersant is a polycarboxylic polyether copolymer.

8. Low viscosity milk of lime according to claim 7, wherein the polycarboxylic polyether copolymer has a main chain containing (meth)acrylate units and lateral chains comprising oxyethylene or oxypropylene groups.

9. Low viscosity milk of lime according to claim 1, wherein the fine particle content is higher than 40 wt with respect to the total weight of the low viscosity milk of lime.

Description

[0038] Other characteristics and advantages of the present invention will be derived from the non-limitative following description, and by making reference to the figures and examples.

[0039] FIG. 1 is a graphic representation of the viscosity evolution over time of the milk if lime containing different amounts of a mixture of fructose and glucose with a polymer dispersant.

[0040] FIG. 2 is a graphic representation of the viscosity evolution over time of the milk of lime containing different amounts of xylitol with a polymer dispersant.

[0041] FIG. 3 is a graphic representation of the viscosity evolution over time of the milk if lime containing different amounts of sodium gluconate with a polymer dispersant.

[0042] FIG. 4 is a graphic representation of the viscosity evolution over time of a comparative milk of lime containing different amounts of sucrose (saccharose) and a polymer dispersant.

[0043] FIG. 5 is a graphic representation of the viscosity evolution over time of (i) a comparative milk of lime containing sucrose (saccharose) and a polymer dispersant, and (ii) the corresponding milk of lime according to the invention.

[0044] The present invention relates to a low viscosity milk of lime showing a viscosity over 28 days lower than or equal to 600 mPa.Math.s, more preferably lower or equal to 300 mPa.Math.s, therefore having improved storage properties.

[0045] The low viscosity milk of lime according to the present invention comprises fine lime particles in suspension in an aqueous phase with at least a first dispersant and a second dispersant, said fine lime particles having a particle size distribution with a characteristic diameter d.sub.25 equal to or lower than 2 ?m as measured by laser diffraction with methanol as carrier solvent.

[0046] The low viscosity milk of lime contains typically a fine lime particles content comprised between 30 and 75 wt %. The first dispersant is a dispersant polymer, preferably a polycarboxylate polyether copolymer and preferably a poly(meth)acrylate polyether copolymer with oxyethylene and/or oxypropylene units in the lateral side-chains on a polycarboxylate backbone. The first dispersant is typically a comb copolymer. The first dispersant is present at an amount of 0.03 to 0.24 wt % non-volatile matter, preferably between 0.04 to 0.20 wt %, preferably lower than or equal to 0.18 wt % or even lower than or equal to 0.16 wt % non-volatile matter with respect to the solid matter content of the low viscosity milk of lime.

[0047] The second dispersant is present at an amount of 0.11 and 1.15 wt %, preferably between 0.15 and 1.1 wt %, more particularly between 0.25 and 0.95 wt % non-volatile matter with respect to the total weight of the low viscosity milk of lime and comprises either: [0048] (i) sodium gluconate or gluconic acid, [0049] (ii) a mixture of sugar containing at least glucose and fructose, [0050] (iii) xylitol.

[0051] In the milk of lime according to the present invention, the first dispersant and the second dispersant are present together at an amount comprised between 0.11 and 1.15 wt %, preferably between 0.15 and 1.1 wt %, more particularly between 0.25 and 0.95 wt % non-volatile matter with respect to the total weight of the low viscosity milk of lime.

[0052] The low viscosity milk of lime shows a stable viscosity over 28 days lower than or equal to 600 mPa.Math.s, more preferably lower or equal to 300 mPa.Math.s, as measured by a Brookfield DV III Rheometer, with the suitable spindle according to the observed torque or viscosity, typically LV spindle No 3. at 100 rpm with the measurement taken on the 30th second after the rheometer motor was turned on.

[0053] The milk of lime according to the present invention shows a stable viscosity over 28 days lower than or equal to 600 mPa.Math.s, more preferably lower or equal to 300 mPa.Math.s, while showing a polymer dispersant content which is especially low, i.e. comprised between 0.03 to 0.24 wt % non-volatile matter with respect to the solid matter content of the low viscosity milk of lime, when using a selection of carbohydrates in limited amounts.

[0054] Indeed, it has been identified according to the present invention that either sodium gluconate or gluconic acid, xylitol or a mixture of saccharides containing at least glucose and fructose in an amount comprised between 0.10 to 1.0 wt % non-volatile matter, preferably between 0.12 and 0.85 wt % non-volatile matter, more particularly between 0.15 and 0.8 wt % non-volatile matter with respect to the total weight of the low viscosity milk of lime together with a polymer dispersant added to fine hydrate suspension allows to reach a milk of lime with low viscosity over several weeks, at least for 4 weeks, i.e. 28 days, in addition to a reduced consumption of polymer dispersant but also of carbohydrate dispersant in some cases, since the total amount of the first dispersant and the second dispersant is comprised between 0.11 and 1.15 wt %, preferably between 0.15 and 1.1 wt %, more particularly between 0.25 and 0.95 wt % non-volatile matter with respect to the weight of the low viscosity milk of lime.

[0055] The choice of the second dispersant selected between sodium gluconate or gluconic acid, xylitol or a mixture of sugar containing at least glucose and fructose, combined with the other features of the invention, allows to produce such slurries at much reduced additive dosage and better reproducibility. Accordingly, the slurries can be produced more cost efficiently and provide less organic adjuvants to the final use. In the case the slurries are used in water treatment, the slurries also reduce the chemical oxygen demand since any organic carbon source acts as nutrient for undesired microbial growth of the application treatment where the product is finally used). Further, the choice of hydrated limea hydrated lime having a specific surface area measured by nitrogen adsorption manometry and calculated according to the BET (Brunauer. Emmett et Teller) method lower than or equal to 12 m.sup.2/g, preferably lower than or equal to 10 m.sup.2/g, more preferably lower than or equal to 8 m.sup.2/g and most preferably lower than or equal to 6 m.sup.2/g, produces a less viscous & more stable suspensionespecially for the same dosage of carbohydrate & polymer dispersant.

[0056] According to the present invention, the first and the second dispersant can be added in different stages or together.

EXAMPLES

[0057] The particle size distribution in the following examples and comparative examples were measured with a Beckmann-Coulter Diffraction Particle Sizer LS 13 320 by laser diffraction with methanol as carrier solvent, using internal ultrasound for dispersion during 2 minutes with a power of maximum 73 W.

Example 1.Preparation of a Milk of Lime Containing 0.08 Wt % Polymer Dispersant and 0.2 wt % Fructose and Glucose

[0058] A milk of lime containing 45 wt % fine hydrated lime particles with respect to the weight of the milk of lime, 0.08 wt % non-volatile matter with respect to the weight of the milk of lime of Neomere?Tech 646 from Chryso SAS, i.e. a polycarboxylate polyether copolymer as second dispersant polymer and 0.2 wt % non-volatile matter of fructose and glucose with respect to the weight of the milk of lime added as first dispersant, i.e. an organic stabilizing agent, as a syrup made of 3 sugars is prepared. The syrup contains fructose, glucose and sucrose at a ratio 1/1/1 and present a sugar content of 66% sugar and 34% water. The syrup is added at an amount of 0.68 wt % to reach a final amount of glucose and fructose in the milk of lime of 0.2 wt %

[0059] The milk of lime is prepared as follows:

[0060] 2000 g of tap water are placed in a 5 dm.sup.3 plastic beaker. 18.5 g invert sugar syrup with a dissolved, total carbohydrate content of 70 wt %, containing sucrose, fructose and glucose in equal amounts, are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0061] 1636 g dry lime hydrate with a BET specific surface area of 10.3 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45% wt solid content with respect to the weight of the milk of lime. The added hydrated lime particles have a particle size distribution with characteristic diameters as follows: d.sub.25 of 2.5 ?m, d.sub.50 of 9.9 ?m, d.sub.90 of 55.3 ?m and d.sub.98 of 99.8 ?m.

[0062] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain fine hydrated lime particles with a particle size distribution with characteristic diameters as follows: d.sub.25 of 1.14 ?m, d.sub.50 of 2.74 ?m, d.sub.90 of 12.7 ?m and a d.sub.98 of 27.3 ?m.

[0063] To 2132 g of this suspension, 8.5 g of Chryso Neomere? Tech 646 are added under vigorous agitation with the same stirrer as above at 600 rpm for a concentration of 0.080 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension.

[0064] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the viscometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement but left otherwise undisturbed. Results over 28 days are given in FIG. 1.

Example 2.Preparation of a Milk of Lime Containing 0.08 wt % Polymer Dispersant and 0.135 wt % Fructose and Glucose

[0065] 2000 g of tap water are placed in a 5 dm.sup.3 plastic beaker. 10.5 g said sugar syrup of Example 1 with a dissolved, total carbohydrate content of 70 wt %, containing sucrose, fructose and glucose in equal amounts, are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0066] 1636 g of the same dry hydrated lime particles as Example 1 with a BET specific surface area of 10.3 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content. The added dry hydrated lime particles have particle size distribution with characteristic diameters as follows: d.sub.25 of 2.5 ?m, d.sub.50 of 9.9 ?m, d.sub.90 of 55.3 ?m and d.sub.98 of 99.8 ?m.

[0067] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain fine hydrated lime particles with a particle size distribution with characteristic diameters as follows: d.sub.25 of 1.16 ?m, d.sub.50 of 2.82 ?m, a d.sub.90 of 12.6 ?m and a d.sub.98 of 25.3 ?m.

[0068] To 2290 g of this suspension, 9.2 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 600 rpm for a concentration of 0.080 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension.

[0069] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the viscometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 1.

Example 3.Preparation of a Milk of Lime Containing 0.225 wt % Gluconate Na and 0.08 wt % Polymer Dispersant

[0070] 5000 g of tap water are placed in a 10 dm.sup.3 plastic beaker. 20.5 g dry sodium gluconate (p.a. quality of Sigma-Aldrich) are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0071] 4091 g of dry hydrated lime particles a with a BET specific surface area of 7.9 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content. The added dry hydrated lime particles have a particle size distribution with characteristic diameters as follows: d.sub.25 of 2.0 ?m, d.sub.50 of 5.0 ?m, d.sub.90 of 51.9 ?m and d.sub.98 of 122.2 ?m.

[0072] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain fine hydrated lime particles with a particle size distribution with characteristic diameters as follows; d.sub.25 of 1.38 ?m, d.sub.50 of 2.78 ?m, d.sub.90 of 7.43 ?m and d.sub.98 of 10.56 ?m.

[0073] To 2560 g of this suspension, 10.2 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.08 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension. The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 4.Preparation of a Milk of Lime Containing 0.225 wt % Sodium Gluconate and 0.04 wt % Polymer Dispersant

[0074] The same milled suspension as in Example 4 is used.

[0075] To 2220 g of this suspension, 4.4 g of Chryso Neomere?Ttech 646 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.04 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension (with respect to the weight of the milk of lime).

[0076] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the viscometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 5.Preparation of a Milk of Lime Containing 0.135 wt % Sodium Gluconate and 0.08 wt % Polymer Dispersant

[0077] 5000 g of tap water are placed in a 10 dm.sup.3 plastic beaker. 12.3 g dry sodium gluconate (p.a. quality of Sigma-Aldrich) are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm (during 15 min.

[0078] 4091 g of the same dry lime hydrate as in Example 3 & 4 with a BET specific surface area of 7.9 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content with respect to the weight of the milk of lime. The added hydrated lime particles have a particle size distribution with characteristic diameters as follows: d.sub.25 of 2.0 ?m, d.sub.50 of 5.0 ?m, d.sub.90 of 51.9 ?m and d.sub.98 of 122.2 ?m.

[0079] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain a particle size distribution of the hydrated lime particles with characteristic diameters such as follows: d.sub.25 of 1.50 ?m, d.sub.50 of 3.17 ?m, d.sub.90 of 9.03 ?m and d.sub.98 of 13.80 ?m.

[0080] To 2167 g of this suspension, 8.7 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.08 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension.

[0081] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 6.Preparation of a Milk of Lime Containing 0.135 wt % Sodium Gluconate and 0.08 wt % Polymer Dispersant

[0082] The same milled suspension as in Example 5 is used. To 2422 g of this suspension, 4.8 g of Coatex Rheosperse 4050 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.08 wt % non-volatile matter of Rheosperse 4050 per mass of total suspension (with respect to the weight of the milk of lime). The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 7.Preparation of a Milk of Lime Containing 0.3375 wt % Sodium Gluconate and 0.08 wt % Polymer Dispersant

[0083] 5000 g of tap water are placed in a 10 dm.sup.3 plastic beaker. 30.7 g dry sodium gluconate (p.a. quality of Sigma-Aldrich) are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0084] 4091 g of the same dry hydrated lime particles as in Example 3 to 6 with a BET specific surface area of 7.9 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content. The content of sodium gluconate is thus 0.75 wt % per weight dry hydrate (with respect to the weight of the fine hydrated lime particles) or 0.3375 wt % per wt suspension (with respect to the weight of the milk of lime). The added dry hydrated lime particles have a particle size distribution with characteristic diameter as follows: d.sub.25 of 2.0 ?m, d.sub.50 of 5.0 ?m, d.sub.9% of 51.9 ?m and a d.sub.98 of 122.2 ?m.

[0085] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain a fine hydrated lime particles with a particle size distribution with characteristic diameter such as follows: d.sub.25 of 1.30 ?m, d.sub.50 of 2.58 ?m, d.sub.90 of 8.59 ?m and d.sub.98 of 10.18 ?m.

[0086] To 2309 g of this suspension, 9.2 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.08 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension.

[0087] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 8.Preparation of a Milk of Lime Containing 0.3375 wt % Sodium Gluconate and 0.12 wt. Polymer Dispersant

[0088] The same milled suspension as for Example 7 is used.

[0089] To 2047 g of this suspension, 12.3 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.12 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension (with respect to the weight of the milk of lime).

[0090] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 9.Preparation of a Milk of Lime Containing 0.3375 wt % Sodium Gluconate and 0.16 wt % Polymer Dispersant

[0091] The same milled suspension as in Example 7 is used.

[0092] To 2060 g of this suspension, 8.2 g of Coatex Rheosperse 4050 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.16 wt % non-volatile matter of Coatex Rheosperse 4050 per mass of total suspension (with respect to the weight of the milk of lime).

[0093] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 3.

Example 10.Preparation of a Milk of Lime Containing 0.3375 wt % Xylitol and 0.16 wt % Polymer Dispersant

[0094] The same milled suspension as for Example 7 is used.

[0095] To 2177 g of this suspension, 8.7 g of Coatex Rheosperse 4050 are added under vigorous agitation with the same stirrer as above at 700 rpm for a concentration of 0.16 wt % non-volatile matter of Coatex Rheosperse 4050 per mass of total suspension (with respect to the weight of the milk of lime).

[0096] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 2.

Comparative Example 1.Preparation of a Milk of Lime Containing 0.07 wt % Fructose and Glucose and 0.08 wt % Polymer Dispersant

[0097] 2000 g of tap water are placed in a 5 dm.sup.3 plastic beaker. 5.4 g invert sugar syrup with a dissolved, total carbohydrate content of 60 wt %, containing sucrose, fructose and glucose in equal amounts, are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0098] 1636 g of the same dry lime hydrate as Example 1 with a BET specific surface area of 10.3 m.sup.2/g is added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content with respect to the weight of the milk of lime. The total content of carbohydrate is thus 0.23 wt % per weight dry hydrate (with respect to the weight of the fine hydrated lime particles), while the combined content in fructose & glucose is 0.15 wt % per weight dry hydrate (with respect to the weight of the fine hydrated lime particles) or 0.07 wt % per weight suspension (with respect to the weight of the milk of lime). The added dry hydrated lime particles have a particle size distribution with characteristic diameters such as follows: d.sub.25 of 2.5 ?m, d.sub.50 of 9.9 ?m, d.sub.90 of 55.3 ?m and d.sub.98 of 99.8 ?m.

[0099] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain fine hydrated lime particles with a particle size distribution with characteristic diameters as follows: d.sub.25 of 1.16 ?m, d.sub.50 of 2.72 ?m, d.sub.90 of 16.92 ?m and d.sub.98 of 24.05 ?m.

[0100] To 2229 g of this suspension, 8.9 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 600 rpm for a concentration of 0.080 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension (with respect to the weight of the milk of lime).

[0101] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 1.

Comparative Example 2.Preparation of a Milk of Lime Containing 0.10 wt % Sucrose and 0.08 wt % Polymer Dispersant

[0102] 2000 g of tap water are placed in a 5 dm.sup.3 plastic beaker. 6. g sucrose (table sugar) are added to the water and dissolved by gentle agitation with a 3-bladed propeller stirrer, turning at 300 rpm during 15 min.

[0103] 1636 g of the same dry hydrated lime particles as Example 1 with a BET specific surface area of 10.3 m.sup.2/g are added to the water and dispersed by the same gentle agitation during 30 min into a homogeneous suspension of 45 wt % solid content with respect to the weight of the milk of lime.

[0104] The content of sucrose is thus 0.23 wt % per weight dry hydrate (with respect to the weight of the fine hydrated lime particles) or 0.10 wt % per weight total suspension (with respect to the weight of the milk of lime). The added dry hydrated lime particles have a particle size distribution with characteristic diameters as follows: d.sub.25 of 2.5 ?m, d.sub.50 of 9.9 ?m, d.sub.90 of 55.3 ?m and d.sub.98 of 99.8 ?m.

[0105] The suspension is milled by a lab scale rotary bead mill with a (empty) volume of 1.4 dm.sup.3 using yttrium-stabilized zirconium oxide beads with a mean diameter of 1.2 mm to obtain fine hydrated lime particles with a particle size distribution with characteristic diameters as follows: d.sub.25 of 1.22 ?m, d.sub.50 of 3.15 ?m, d.sub.90 of 16.23 ?m and d.sub.98 of 38.44 ?m.

[0106] To 2004 g of this suspension, 8.0 g of Chryso Neomere?Tech 646 are added under vigorous agitation with the same stirrer as above at 600 rpm for a concentration of 0.080 wt % non-volatile matter of Neomere?Tech 646 per mass of total suspension (with respect to the weight of the milk of lime).

[0107] The viscosity is measured by Brookfield DV-3 Rheometer at 100 rpm with the measurement taken on the 30.sup.th second after the rheometer motor was turned on. The used 200 cm.sup.3 sample is only shaken by hand for homogenization before the measurement, but left otherwise undisturbed. Results over 28 days are given in FIG. 4.

Comparative Example 3Preparation of a Milk of Lime as Described in Example 5.2 of WO 2020/0904607

[0108] 6.0 g Rheosperse 4050 of the company Coatex and 2.4 g sucrose (i.e., saccharose) were added to 1800 g tap water and dissolved with a propeller stirrer at 300 rpm as described in WO 2020/0904607.

[0109] To this solution, 1200 g of dry hydrate of a sample of Supercalco 97 (S97) were added and dispersed by the same agitation during 15 min into a homogeneous suspension of 40 wt % solid content with respect to the weight of the milk of lime.

[0110] The content of sucrose is thus 0.2 wt % with respect to the weight of the solid matter content of the milk of lime and the content of the Rheosperse dispersant on a non-volatile base is 0.2 wt % with respect to the weight of the solid matter content of the milk of lime (or 0.08 wt % with respect to the weight of the milk of lime).

[0111] The particle size distribution of the suspension was measured and the following results were obtained: d.sub.25 of 1.99 ?m, d.sub.50 of 4.96 ?m, d.sub.90 of 47.3 ?m and d.sub.98 of 84.2 ?m.

[0112] A 1000 cm.sup.3 sample of the suspension was agitated for 1 hour/day and the viscosity monitored at regular intervals over 28 days (first measurement day 0 was done directly after suspension preparation). Viscosity measurements were conducted with a Brookfield DV-3 Rheometer at rotation speeds of 100 rpm (suspension was only shaken by hand for homogenization before the measurement but left otherwise undisturbed). Results over 28 days are given in FIG. 5.

TABLE-US-00001 Viscosity [mPa .Math. s] Day after (Brookfield DV-3 Preparation @ 100 rpm) Day 0 31 Day 1 195 Day 3 324 Day 7 403 Day 15 675 Day 22 771 Day 28 702

[0113] It is observed that the viscosity increases very quickly (especially from day 0 to day 1), exceeds 600 mPa.Math.s after 15 days and continues to rise in the time thereafter to reach ?700 mPas after 28 days.

Example 11Preparation of a Milk of Lime According to Invention, with Same Mass Dosage in First and Second Dispersants Equivalent to Example 5.2 of WO 2020/0904607

[0114] 6.0 g Rheosperse 4050 of the company Coatex and 3.6 g invert sugar syrup (with a dissolved, total carbohydrate content of 70 wt %, containing sucrose, fructose and glucose in equal amounts) were added to 1800 g tap water and dissolved with a propeller stirrer at 300 rpm.

[0115] To this solution, 1200 g of the same dry hydrate sample as in Comparative Example 3 (Supercalco 97, S97, same batch) were added and dispersed by the same agitation during 15 min into a homogeneous suspension of 40 wt % solid content with respect to the weight of the milk of lime.

[0116] The content of invert sugar is thus 0.2 wt % per weight dry hydrate (corresponding to 0.0533 wt % of glucose and fructose with respect to the weight of the milk of lime) and the content of the Rheosperse dispersant on a non-volatile base is 0.2 wt % with respect to the weight of the solid matter content of the milk of lime (or 0.08 wt % with respect to the weight of the suspension).

[0117] The particle size distribution of the suspension was measured and the following results were obtained: d.sub.25 of 1.84 ?m, d.sub.50 of 4.61 ?m, d.sub.90 of 44.6 ?m and d.sub.98 of 78.3 ?m.

[0118] A 1000 cm.sup.3 sample of the suspension was agitated for 1 hour/day and the viscosity monitored at regular intervals over 28 days (first measurement day 0 was done directly after suspension preparation). Viscosity measurements were conducted with a Brookfield DV-3 Rheometer at rotation speeds of 100 rpm (suspension was only shaken by hand for homogenization before the measurement but left otherwise undisturbed). Results over 28 days are given in FIG. 5.

TABLE-US-00002 Viscosity [mPa .Math. s] Day after (Brookfield DV-3 Preparation @ 100 rpm) Day 0 37 Day 1 117 Day 3 167 Day 7 229 Day 15 356 Day 22 354 Day 28 402

[0119] It is observed that the viscosity as measured by Brookfield DV-3 Rheometer at 100 rpm is significantly below 600 mPa.Math.s after 15 days and remains roughly stable in the time thereafter, to reach ?400 mPas after 28 days.

[0120] It should be understood that the present invention is not limited to the described embodiments and that variations can be applied without going outside of the scope of the appended claims.