SOLID PARTICULATE CALCIUM NITRATE COMPOSITION COMPRISING A SOLID PARTICULATE SILICATE AS AN ANTI-CAKING AGENT

Abstract

The invention relates to a solid particulate calcium nitrate composition having particles with an average particle size of between 0.1 and 1 mm and comprising an anti-caking agent, wherein the anti-caking agent consists of a solid particulate silicate with an average particle size of between 0.05 and 750 m. The invention furthermore relates to a pre-blend binder composition comprising such a solid particulate calcium nitrate composition. Also a dry mortar mix or tile adhesive composition and a dry concrete mix comprising an aggregate and such a pre-blend binder composition. Also a method for producing a solid particulate calcium nitrate composition, the use of a solid particulate silicate as anti-caking agent for a solid particulate calcium nitrate composition and the use of a solid particulate calcium nitrate composition as a setting accelerator for cementitious pre-blend binder composition are disclosed.

Claims

1. A solid particulate calcium nitrate composition having particles with an average particle size of between 0.1 mm and 1 mm and comprising an anti-caking agent, CHARACTERIZED IN THAT the anti-caking agent consists of a solid particulate silicate with an average particle size of between 0.05 m and 750 m and wherein the solid particulate silicate is present in an amount of 0.01 weight % to 2 weight %.

2. Solid particulate calcium nitrate composition according to claim 1, wherein the solid particulate calcium nitrate composition further comprises a solid particulate anhydrous calcium nitrate and having particles with an average particle size of between 0.1 mm and 1 mm.

3. Solid particulate calcium nitrate composition according to claim 1, wherein the solid particulate calcium nitrate composition further comprises a solid particulate potassium calcium nitrate and having particles with an average particle size of between 0.1 mm and 1 mm.

4. Solid particulate calcium nitrate composition according to claim 1, wherein the solid particulate calcium nitrate composition further comprises solid particulate ammonium calcium nitrate and having particles with an average particle size of between 0.1 mm and 1 mm.

5. Solid particulate calcium nitrate composition according to claim 2, wherein the solid particulate anhydrous calcium nitrate, the solid particulate potassium calcium nitrate or the solid particulate ammonium calcium nitrate and the solid particulate silicate have a similar average particle size.

6. Solid particulate calcium nitrate composition according to claim 1, wherein the solid particulate silicate is present in an amount of 0.05 weight % to 2 weight %, and most preferably in an amount of 0.1 weight % to 1 weight % of the weight content of the solid particulate calcium nitrate composition.

7. Solid particulate calcium nitrate composition according to claim 1, wherein the solid particulate silicate is a solid particulate silicon dioxide.

8. Solid particulate calcium nitrate composition according to claim 7, wherein the solid particulate silicate is an amorphous solid particulate silicon dioxide.

9. Solid particulate calcium nitrate composition according to claim 8, wherein the amorphous solid particulate silicon dioxide consists of a silica fume, a diatomaceous earth or mixtures thereof.

10. Solid particulate calcium nitrate composition according to claim 1, wherein the composition has a caking number below 20.

11. A pre-blend binder composition comprising a hydraulic binder and 0.5 weight % to 5 weight % solid particulate calcium nitrate composition according to claim 1.

12. A dry mortar mixture or a tile adhesive composition, at least comprising a fine aggregate, preferably sand; and a pre-blend binder composition according to claim 11.

13. A dry concrete mixture, at least comprising a coarse aggregate consisting of stones and/or gravel, and a fine aggregate, preferably sand; and a pre-blend binder composition according to claim 11.

14. A method for producing a solid particulate calcium nitrate composition according to claim 1, comprising the steps of: providing a freshly produced and cooled anhydrous solid particulate calcium nitrate, solid particulate potassium calcium nitrate or solid particulate ammonium calcium nitrate, having particles with an average particle size of between 0.1 mm and 1 mm; and adding to the freshly produced and cooled anhydrous solid particulate calcium nitrate, solid particulate potassium calcium nitrate or solid particulate ammonium calcium nitrate, a solid particulate silicate having particles with an average particle size of between 0.05 m and 750 m in an amount of 0.01 weight % to 2.00 weight % of the weight content of the solid particulate calcium nitrate composition as anti-caking agent for the anhydrous solid particulate calcium nitrate, solid particulate potassium calcium nitrate or solid particulate ammonium calcium nitrate.

15. The method according to claim 14, wherein the solid particulate calcium nitrate composition further comprises a solid particulate anhydrous calcium nitrate and having particles with an average particle size of between 0.1 mm and 1 mm.

16. The method according to claim 14, wherein the solid particulate calcium nitrate composition further comprises a solid particulate potassium calcium nitrate and having particles with an average particle size of between 0.1 mm and 1 mm.

17. The method according to claim 14, wherein the solid particulate calcium nitrate composition further comprises solid particulate ammonium calcium nitrate and having particles with an average particle size of between 0.1 and 1 mm.

18. The method according to claim 14, wherein the solid particulate anhydrous calcium nitrate, the solid particulate potassium calcium nitrate or the solid particulate ammonium calcium nitrate and the solid particulate silicate have a similar average particle size.

19. The method according to claim 14, wherein the solid particulate silicate is present in an amount of 0.01 to 2.00 weight %, preferably in an amount of 0.05 to 2 weight %, and most preferably in an amount of 0.1 to 1 weight % of the weight content of the solid particulate calcium nitrate composition?

20. The method according to claim 14, wherein, the solid particulate silicate is a solid particulate silicon dioxide.

21. The method according to claim 20, wherein the solid particulate silicate is an amorphous solid particulate silicon dioxide.

22. The method according to claim 21, wherein the amorphous solid particulate silicon dioxide consists of a silica fume, a diatomaceous earth or mixtures thereof.

23. The method according to claim 14, wherein the composition has a caking number below 20.

24. (canceled)

25. A setting accelerator for a cementitious binder comprising the solid particulate calcium nitrate composition according to claim 1.

26. The setting accelerator according to claim 25, wherein the cementitious binder is used in a dry mortar mixture, a dry concrete mixture or a tile adhesive composition.

Description

DESCRIPTION OF THE FIGURES

[0076] FIG. 1 shows a graphical representation of the weight measurements (related to the water uptake) of the different samples as stored in closed containers after 1 day, 1 week and 1 month;

[0077] FIG. 2 shows a graphical representation of the weight measurements (related to the water uptake) of the same samples of FIG. 1 as stored in open containers after 1 day, 1 week and 1 month;

[0078] FIG. 3 shows a diagram of the test results of NitCal 99 according to the second flowability test method using the aero-flow powder flowability analyzer;

[0079] FIG. 4 shows a diagram of the test results of NitCal 99+1 weight % Damolin DA 100G according to the second flowability test method using the aero-flow powder flowability analyzer.

DETAILED DESCRIPTION OF THE INVENTION

[0080] The present invention relates to a solid particulate calcium nitrate composition having particles with an average particle size of between 0.1 mm and 1 mm, this composition comprising a solid particulate silicate with an average particle size of between 0.05 m and 750 m. It has been shown that the solid particulate silicate is effective in keeping a solid particulate calcium nitrate composition with the specific average particle size (further called in the description calcium nitrate powder), a free-flowing powder, even after exposure to air with a 77% relative humidity for 24 hours at 20 C., in a range of preferably 0.01 weight % to 5.00 weight %, more preferably 0.05 weight % to 2.00 weight %, and most preferably 0.1 weight % to 1 weight % of the weight content of the solid particulate calcium nitrate composition.

[0081] Calcium nitrate is an inorganic compound with the formula Ca(NO.sub.3).sub.2. This colourless salt absorbs moisture from the air and is commonly found as a tetrahydrate. It is mainly used as a component in fertilizers. Known related salts are ammonium pentacalcium nitrate decahydrate and potassium pentacalcium nitrate decahydrate. Different calcium nitrate salts are available from Yara International ASA (Oslo, Norway) under the trademark NitCal (solids with a concentration of about 76 and 78 weight % of calcium nitrate and solutions of about 45 and 50 weight %).

[0082] The solid particulate calcium nitrate composition can next to the solid particulate silicate with particles having the specific particle size, also comprise a number of different related calcium nitrate salts, i.e. [0083] a solid particulate anhydrous calcium nitrate; [0084] a solid particulate potassium calcium nitrate; or [0085] a solid particulate ammonium calcium nitrate;
all having particles with an average particle size of between 0.1 and 1 mm.

[0086] The solid particulate potassium calcium nitrate and the solid particulate ammonium calcium nitrate are preferably double salts of calcium nitrate with potassium or ammonium. A double salt is a salt containing more than one cation or anion, and is obtained by a combination of two different salts which were crystallized in the same regular ionic lattice. Such compositions are of special interest in the fertilizer industry. It is remarked that the term ammonium calcium nitrate refers to ammonium pentacalcium nitrate decahydrate (CAS-No.: 15245-12-2; EC-No.: 239-289-5). This shall not be confused with calcium ammonium nitrate what is the technical term for the blend of limestone and ammonium nitrate. The term potassium calcium nitrate refers to potassium pentacalcium nitrate decahydrate (CAS-No.: 905593-70-6; Product notification: 07-16-0045-00).

[0087] The average particle size of the solid particulate silicate as the anti-caking agent preferably is 0.05 to 750 m, more preferably 0.01 m to 500 m, even more preferably 0.10 to 200 m, still even more preferably 0.15 to 100 m, most preferably 0.20 to 50 m, typically from 0.30 to 10 m and especially from 0.50 to 1 m.

[0088] Most preferably, the solid particulate anhydrous calcium nitrate, the solid particulate potassium calcium nitrate or the solid particulate ammonium calcium nitrate and the solid particulate silicate have a similar average particle size, preferably being around 100 m.

[0089] The average particle size of the particles of the different compositions and powders as mentioned in this patent application are measured by means of particle segregation. In particle segregation, particulate solids tend to segregate by virtue of differences in the size, and also physical properties such as volume, density, shape and other properties of particles of which they are composed. In the present example the particles obtained were segregated in a sieve shaker using a stack of woven wire mesh sieves having mesh sizes of 2 mm, 1.5 mm, 1 mm, 0.5 mm, 0.1 mm and 0.05 mm, respectively. Additional sieves can be used to obtain additional segregation.

[0090] The solid particulate silicate that is preferably applied as the anti-caking agent is a solid particulate silicon dioxide, more preferably an amorphous solid particulate silicon dioxide and most preferably a silica fume and diatomaceous earth.

[0091] The solid particulate calcium nitrate composition preferably has a caking number of lower than 20 and more preferably lower than 10.

[0092] In the method for producing a solid particulate calcium nitrate composition according to the invention as described above, the following steps are included: [0093] providing a freshly produced and cooled anhydrous solid particulate calcium nitrate, a solid particulate potassium calcium nitrate or a solid particulate ammonium calcium nitrate, having particles with an average particle size of between 0.1 and 1 mm; [0094] adding to the freshly produced and cooled anhydrous solid particulate calcium nitrate, a solid particulate potassium calcium nitrate or a solid particulate ammonium calcium nitrate, a solid particulate silicate having particles with an average particle size of between 0.05 m and 750 m in an amount of 0.01 weight % to 0.05 weight % of the weight content of the solid particulate calcium nitrate composition. As an anti-caking agent for the anhydrous solid particulate calcium nitrate, a solid particulate potassium calcium nitrate or a solid particulate ammonium calcium nitrate.

[0095] This anhydrous solid particulate calcium nitrate, a solid particulate potassium calcium nitrate or a solid particulate ammonium calcium nitrate, all having particles with an average particle size of between 0.1 mm and 1 mm can be produced by means of an industrial turbo-dryer such as a turbo-dryer (also called turbo-concentrator) as described in European patent 0749772 and manufactured by the company VOMM Impianti e Processi, Rozzano (MI). A method for producing an anhydrous powder having [0096] a calcium nitrate content of between 92 and 99.9 weight %; [0097] a water content of between 0.1 and 8 weight %; and [0098] a particle size of between 0.05 and 1.5 mm,
wherein the method comprises the step of subjecting a calcium nitrate solution having a water content of between 70 weight % and 15 weight % of water and a calcium nitrate content of between 30 weight % and 80 weight % to a drying step in an industrial turbo-dryer, resulting in the anhydrous calcium nitrate powder, has been described in the co-pending Norwegian patent application no. 20140795 and the co-pending PCT patent application no. PCT/EP2015/064065.

[0099] The mixing of the anti-caking agent with the anhydrous solid particulate calcium nitrate, a solid particulate potassium calcium nitrate or a solid particulate ammonium calcium nitrate to form the final solid particulate calcium nitrate composition is thus done before the anhydrous solid particulate calcium nitrate, the solid particulate potassium calcium nitrate or the solid particulate ammonium calcium nitrate can absorb water from the air. Consequently, the anhydrous solid particulate calcium nitrate, the solid particulate potassium calcium nitrate or the solid particulate ammonium calcium nitrate has the same water content as when it is leaving the production process.

[0100] The solid particulate calcium nitrate composition can be mixed with a binder to form a pre-blend binder composition. Therewith, 0.5 weight % to 5 weight % of solid particulate calcium nitrate composition according to the invention as described in the above paragraph will be mixed with the binder. To form a cementitious pre-blend binder, the binder is a cementitious binder such as cement. Preferably, a hydraulic cement, even more preferably Portland cement, most preferably Portland blast furnace cement, Portland fly ash cement, Portland pozzolan cement or Portland silica fume cement are used.

[0101] The pre-blend binder composition will be lump-free since a free-flowing solid particulate calcium nitrate composition according to the invention as described above will be incorporated into the pre-blend binder composition, through which upon setting, no weak spots will be formed in the hardened product.

[0102] Construction materials such as dry mortar mixtures, tile adhesive compositions and dry concrete mixtures, can be made from a pre-blend binder composition as described above on mixing the pre blend binder composition with aggregates. Depending on the type of construction material, different aggregates are used. To produce for instance a dry mortar mixture, a fine aggregate, preferably sand, is used, while to produce a dry concrete mixture, a mixture of a coarse and a fine aggregate is used, the coarse aggregate preferably consisting of stones and/or gravel, and the fine aggregate preferably being sand. To obtain the construction materials, the pre-blend binder composition according to the invention as described above is mixed with 200 vol % to 900 vol %, preferably 300 vol % to 800 vol %, more preferably 400 vol % to 700 vol % and most preferably 500 vol % to 600 vol % of at least one of the abovementioned aggregates.

[0103] The solid particulate calcium nitrate composition will cause a shorter setting time of the construction materials. The initial setting time of the pre-blend binder composition according to the invention as described above and of the construction materials is preferably from 15 minutes to 60 minutes, more preferably 20 minutes to 50 minutes, even more preferably 30 minutes to 40 minutes, and most preferably 35 minutes. The present invention will be now described in more details, referring to examples that are not limitative.

EXAMPLES

Example 1

[0104] Freshly produced and cooled anhydrous calcium nitrate powder (99 weight % calcium nitrate, 1 weight % crystal water, 90 weight % of the particles having a particle size between 0.1 mm-1 mm, 5 weight % larger than 1 mm, 5 weight % smaller than 0.1 mm, determined by sieve analysis) is mixed with 0.05 weight % silica fume (compared to the weight of the anhydrous calcium nitrate powder). The mixture is blended thoroughly. In parallel, a sample without addition of silica fume is used as a reference. The samples are exposed to a standard laboratory air (20 C., 77% relative humidity) over one day (24 hours). It could be visually observed that the powder with silica fume addition remains free-flowing, whereas the powder without silica fume forms lumps.

Example 2

[0105] Freshly produced and cooled anhydrous calcium nitrate powder (99 weight % calcium nitrate, 1 weight % crystal water, 90 weight % of the particles having a particle size between 0.1 mm-1 mm, 5 weight % larger than 1 mm, 5 weight % smaller than 0.1 mm determined by sieve analysis) is mixed with 1.00 weight % silica fume, compared to the weight of the anhydrous calcium nitrate powder. The mixture is blended thoroughly. In parallel, a sample without addition of silica fume is used as a reference. The samples are exposed to a standard laboratory air (20 C., 77% relative humidity) for three days (72 hours). It could be visually observed that the powder with silica fume addition remains free-flowing whereas the powder without silica fume forms lumps.

Example 3

[0106] Freshly produced and cooled potassium calcium nitrate powder (77 weight % calcium nitrate, 8 weight % potassium nitrate, 15 weight % crystal water, 90 weight % of the particles having a particle size between 0.1 mm-1 mm, 5 weight % larger than 1 mm, 5 weight % smaller than 0.1 mm determined by sieve analysis) is mixed with 0.10 weight % of silica fume compared to the weight content of the potassium calcium nitrate powder. The mixture is blended thoroughly. In parallel, a sample without addition of silica fume is used as a reference. The samples are exposed to a standard laboratory air (20 C., 70% relative humidity) over one day (24 hours). It could be visually observed that the powder with silica fume addition remains free-flowing whereas the powder without silica fume forms lumps.

[0107] It is remarked that the behavior of ammonium calcium nitrate powder is the same as the behavior of potassium calcium nitrate powder.

Example 4

[0108] Freshly produced and cooled pure anhydrous calcium nitrate powder (99 weight % calcium nitrate, 1 weight % crystal water (90 weight % of the particles having a particle size between 0.1 mm-1 mm, 5 weight % larger than 1 mm, 5 weight % smaller than 0.1 mm determined by sieve analysis) is mixed with 1 weight % diatomaceous earth (0.1 mm average particle size) (compared to the weight of the anhydrous calcium nitrate anhydrous powder). The mixture is blended thoroughly. In parallel, a sample without addition of diatomaceous earth is used as a reference. The samples are exposed to a standard laboratory air (20 C., 77% relative humidity) over one day (24 hours). It could be visually observed that the powder with diatomaceous earth addition remains free-flowing whereas the powder without silica fume forms lumps.

Example 5

[0109] In a lab test, the water take up of a mixture of a pure anhydrous calcium nitrate powder (99 weight % calcium nitrate, 1 weight % crystal water, 90 weight % of the particles having a particle size between 0.1 mm-1 mm, 5 weight % larger than 1 mm, 5 weight % smaller than 0.1 mm determined by sieve analysis) and an anti-caking agent [0110] according to the state of the art, i.e. talcum powder (that is commonly used as an anti-caking agent in NPK products), more specifically Finntalc M30-SQ of Mondo Minerals B.V., having a median particle size (50%) of 10 m, and [0111] according to the invention, i.e. Damolin DA100G, which is a diatomaceous earth product;
have been compared.

[0112] The Damolin DA100G has the following specifications:

TABLE-US-00001 Sieve analysis Max Average >45 m 28% 21.7% >63 m 18% 14.1% >90 m 12% 7.3% >250 m 4% 0.2%

[0113] In the table I below, different samples, consisting of different amounts of pure anhydrous calcium nitrate powder that is mixed with on the one hand talcum powder and on the other hand the diatomaceous earth product, that have been tested are shown. All freshly mixed samples initially weighed 100 g.

TABLE-US-00002 TABLE I Different samples consisting of different amounts of pure anhydrous calcium nitrate powder that is mixed with on the one hand talcum powder and on the other hand the diatomaceous earth product Pure anhydrous CN powder Damolin DA 100G Finntalc M30 - SQ Sample (weight %) (weight %) (weight %) 1 98 2 0 2 99 1 0 3 99.9 0.1 0 4 98 0 2 5 99 0 1 6 99.9 0 0.1

[0114] The lab test consisted of storing the different samples of table I on a lab bench in an open and a closed container. After 1 day, 1 week and 1 month, the samples were weighed (see table II) and evaluated visually. The measurement results are given in table II below.

TABLE-US-00003 TABLE II Weight of the samples of table I in an open and closed container after 1 day, 1 week and 1 month storage on a lab bench Weight increase [g] 1 day 1 week 1 month Sample closed open closed open closed open 1 0.01 0.62 0.03 3.96 0.24 16.04 2 0.01 0.66 0.03 2.96 0.21 15.83 3 0.01 0.14 0.02 3.30 0.18 15.05 4 0.01 0.73 0.03 3.79 0.19 15.94 5 0.01 0.72 0.02 3.91 0.18 16.48 6 0.00 0.72 0.01 3.68 0.18 16.70

[0115] In FIG. 1, a graphical representation of the weight measurements (related to the water uptake) of the samples 1-6 as stored in closed containers is shown, while in FIG. 2 a graphical representation of the weight measurements (related to the water uptake) of the samples 1-6 as stored in open containers is shown.

[0116] Out of these weight measurements, it can be concluded that the addition of the Damolin DA100G product leads to a higher or at least a similar water uptake over time compared to the Talcum powder. The differences are minor.

[0117] In the table III below, the impact of the talcum powder and the diatomaceous earth product on the lump formation and the caking of the pure anhydrous calcium nitrate powder is shown.

TABLE-US-00004 TABLE III Impact of talcum powder and diatomaceous earth product on the on the lump formation and the caking of the pure anhydrous calcium nitrate powder Lump formation and caking 1 day 1 week 1 month Sample closed open closed open closed open 1 OK Layer OK Increased Soft lumps Caked 2 decreasing layer 3 Caked One lump 4 Significant Caked 5 layer 6

[0118] Out of table III, it can be concluded that the addition of the diatomaceous earth product to an opened sample does not give protection against lump formation and caking. However, the addition of 1 weight % of the diatomaceous earth product to the pure anhydrous calcium nitrate powder seems to be sufficient to prevent caking up to one month. Also the lump formation is strongly reduced.

Example 6

[0119] Two samples were tested by means of the flowability test methods as described below, i.e.; [0120] NitCal 99, which is calcium nitrate with a purity of 99 weight %; [0121] NitCal 99 with 1 weight % of Damolin DA 100G.

Test Method 1

[0122] The first test method is the flowability test method according to the European Pharmacopoeia method 2.9.16. Flowability. This flowability test is intended to determine the ability of divided solids (for example, powders and granules) to flow vertically under defined conditions. According to the flow properties of the material to be tested, funnels with or without stem, with different angles and orifice diameters are used. The funnel is maintained upright by a suitable device. The assembly must be protected from vibrations.

[0123] The method steps for this test are as follows: introduce without compacting into a dry funnel, whose bottom opening has been blocked by suitable means, a test sample weighed with 0.5 percent accuracy. The amount of the sample depends on the apparent volume and the apparatus used. Unblock the bottom opening of the funnel and measure the time needed for the entire sample to flow out of the funnel. Carry out three of these determinations.

[0124] The funnel used here had an opening of 25 mm.

[0125] The flowability is expressed in seconds and tenths of seconds, related to 100 g of sample (s/100 g). The results depend on the storage conditions of the material to be tested.

Test Method 2

[0126] The second test method is determining the flowability using an aero-flow powder flowability analyzer. In this test method, the samples are filled in a cylindrical, see-through drum that rotates slowly around its horizontal axis at a constant speed. When the angle on the surface of the sample becomes too large, the powder will flow towards the bottom of the drum. This can be compared with an avalanche. The instrument records the time interval between the avalanches and the size of the avalanche. Each of the samples was tested for three minutes at three different velocities, i.e. 60 s/rotation, 120 s/rotation and 180 s/rotation.

Results of the Tested Samples Tested by the Test Methods 1 and 2

[0127] Test method 1: NitCal 99 didn't flow through the funnel at all while NitCal 99 with 1 weight % Damolin DA 100G got a result of 0.4 s/100 g-1.0 s/100 g. [0128] Test method 2: NitCal 99+1 weight % Damolin DA 100G has a higher number of avalanches, hence a shorter time between the avalanches than NitCal99. At 60 seconds per rotation, the mean time between the avalanches is reduced from 3.76 seconds when testing NitCal 99 alone to 2.68 seconds when testing NitCal 99+1 weight % Damolin DA 100G. At 120 seconds per rotation, the mean time between the avalanches is reduced from 7.78 seconds when testing NitCal 99 alone to 5.45 seconds when testing NitCal 99+1 weight % Damolin DA 100G. At 180 seconds per rotation, the mean time between the avalanches is reduced from 13.7 seconds when testing NitCal 99 alone to 8.03 seconds when testing NitCal 99+1 weight % Damolin DA 100G. As can be seen in FIGS. 3 and 4, the scribble of the diagram of NitCal 99+1 weight % Damolin DA 100G is more together than the scribble of the diagram of NitCal 99 alone. The more together the scribble in the diagram, the better the flowability.

[0129] Out of the both above test methods, it can be concluded that the flowability of NitCal 99 alone is very poor, while adding an anti-caking agent according to the invention such as a diatomaceous earth product as Damolin DA 100G improves the flowability significantly.