Composition Comprising Calcium Magnesium Compound(s) as Compacts

Abstract

Composition comprising at least one calcium-magnesium compound and a second compound chosen in the group consisting of B.sub.2O.sub.3, NaO.sub.3, calcium aluminate, calcium silicate, calcium ferrite such as Ca.sub.2Fe.sub.2O.sub.5 or CaFe.sub.2O.sub.4, Al, Mg, Fe, Mn, Mo, Zn, Cu, Si, CaF.sub.2, C, CaC.sub.2, CaSi, CaMg, CaFe, FeMn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide or a hydroxide of molybdenum, copper, zinc, and their mixture, in the form of compacts formed with compacted and shaped particles of calcium-magnesium compounds, having a Shatter Test Index of less than 20% and the manufacturing process thereof.

Claims

1. A composition comprising at least one calcium-magnesium compound fitting the formula aCaCO.sub.3.bMgCO.sub.3.xCaO.yMgO.zCa(OH).sub.2.tMg(OH).sub.2.ul, wherein I is impurities; a, b, z, t and u each being mass fractions 0 and 50%, x and y each being mass fractions 0 and 100%, with x+y50% by weight, based on the total weight of said at least one calcium-magnesium compound, characterized in that said at least one calcium-magnesium compound is in the form of particles, said composition has a cumulative calcium and magnesium content in the form of oxides, greater than or equal to 20% by weight based on the total weight of the composition, said composition further comprises at least one second compound selected from the group consisting of B.sub.2O.sub.3, NaO, calcium aluminate, calcium silicate, calcium ferrite selected from the group consisting of Ca.sub.2Fe.sub.2O.sub.5 and CaFe.sub.2O.sub.4, metal Al, metal Mg, metal Fe, metal Mn, metal Mo, metal Zn, metal Cu, elemental Si, CaF.sub.2 CaC.sub.2, alloys selected from the group consisting of CaSi, CaMg, CaFe, FeMn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide based on molybdenum, an oxide based on copper, an oxide based on zinc, a hydroxide based on molybdenum, a hydroxide based on copper, a hydroxide based on zinc and their mixture, said composition is in the form of compacts, each compact being formed with compacted and shaped particles of calcium-magnesium compounds, said compacts having a Shatter Test Index of less than 20%.

2. The composition according to claim 1, wherein said second compound chosen in the group consisting of B.sub.2O.sub.3, NaO.sub.3, calcium aluminate, calcium silicate, calcium ferrite such as Ca.sub.2Fe.sub.2O.sub.5 or CaFe.sub.2O.sub.4, metal Al, metal Mg, metal Fe, metal Mn, metal Mo, metal Zn, metal Cu, elemental Si, CaF.sub.2, C, CaC.sub.2, alloys such as CaSi, CaMg, CaFe, FeMn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide based on molybdenum, an oxide based on copper, an oxide based on zinc, a hydroxide based on molybdenum, a hydroxide based on copper, a hydroxide based on zinc and their mixture is comprised into the composition at a content equal or greater to 1 weight based on the total weight of the composition.

3. The composition according to claim 1, wherein said second compound is selected from the group consisting of B.sub.2O.sub.3, NaO.sub.3, metal Al, metal Mg, metal Fe, metal Mn, metal Mo, metal In, metal Cu, elemental Si, CaC.sub.2, alloys selected from the group consisting of CaSi, CaMg, Cafe, Mn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide based on molybdenum, an oxide based on copper, an oxide based on zinc, a hydroxide based on molybdenum, a hydroxide based on copper, a hydroxide based on zinc and their mixture and is comprised into the composition at a content equal to or lower than 20 weight % based on the total weight of the composition.

4. The composition according to claim 1, wherein said second compound is chosen in the group consisting of CaF.sub.2, calcium ferrites like for instance Ca.sub.2Fe.sub.2O.sub.5 or CaFe.sub.2O.sub.4 and their mixture and is comprised into the composition at a content equal to or lower than 40 weight % based on the total weight of the composition.

5. The composition according to claim 1, wherein said second compound is chosen in the group consisting of calcium aluminate, calcium silicate, carbon and their mixture and is comprised into the composition at a content, equal to or lower than 60 weight % based on the total weight of the composition.

6. The composition according to claim 1, wherein said at least one calcium-magnesium compound has mass fractions such that x+y60% based on the total weight of said at least one calcium-magnesium compound.

7. The composition according to claim 1, wherein said compacts have a Shatter Test index of less than 15%.

8. The composition according to claim 1, wherein the cumulative calcium and magnesium content in the form of oxides is greater than or equal to 40% by weight based on the total weight of the composition.

9. The composition according to claim 1, further comprising at least one third compound selected from the group consisting of an organic additive selected from the group consisting of a binder, a lubricant and their mixture, an oxide selected from the group consisting of an oxide based on aluminum, an oxide based on silicon, an oxide based on iron, an oxide based on manganese, and their mixture, a hydroxide selected from the group consisting of a hydroxide based on aluminum, a hydroxide based on silicon, a hydroxide based on iron, a hydroxide based on manganese and their mixture, preferably at a content equal to or greater than 1 weight % and equal to or lower than 40 weight %, based on the total weight of the composition.

10. The composition according to claim 1, wherein said particles have a size of less than or equal to 7 mm, observable by optical microscopy or by scanning, electron microscopy and before compaction having a size of particles d.sub.100 of less than or equal to 7 mm.

11. The composition according to claim 1, wherein said particles of said at least one calcium-magnesium compound before compaction have a d.sub.90 of less than or equal to 3 mm.

12. The composition according to claim 1, said particles of said at least one calcium-magnesium compound before compaction have a d.sub.50 of less than, or equal to 1 mm.

13. The composition according to claim 1, wherein said compacts are of a global regular and homogeneous shape which is typical of products from methods for shaping fines via a dry route, such shapes being selected form the group consisting of lozenges, tablets, compressed tablets, but with a small asymmetry between the lower (bottom) part and the upper (top) part of said compacts, and have a size comprised between 10 and 100 mm.

14. The composition according to claim 1, wherein said compacts have an average weight per compact of at least 1 g.

15. The composition according to claim 1, wherein said compacts have an average weight per compact of less than or equal to 200 g.

16. The composition according to claim 1, wherein said compacts have an apparent density comprised between 1.5 g/cm.sup.3 and 3 g/cm.sup.3.

17. The composition according to claim 1, wherein said compact includes a through-orifice.

18. The composition according to claim 1, wherein said compact is free of macrodefects, on the basis of simple visual inspection, of inspection under an optical microscope or further of inspection with a scanning electron microscope (SEM).

19. (canceled)

20. A method for making a composition in the form of a compact comprising the following steps: a) providing particles of at least one calcium-magnesium compound fitting the formula aCaCO.sub.3.bMgCO.sub.3.xCaO.yMgO.zCa(OH).sub.2.tg(OH).sub.2.uI, wherein I represents impurities, a, b, z, t and u each being mass fractions 0 and 50%, x and y each being mass fractions 0 and 100%, with xy50% by weight based on the total weight of the calcium-magnesium compound, b) adding at least one second compound to the particles of at least one calcium-magnesium compound, selected from the group consisting of B.sub.2O.sub.3, NaO.sub.3, calcium aluminate, calcium silicate, calcium ferrite such as Ca.sub.2Fe.sub.2O.sub.5 or Ca.sub.2Fe.sub.2O.sub.4, metal Al, metal Mg, metal Fe, metal Mn, metal Mo, metal Zn, metal Cu, elemental Si, CaF.sub.2C, CaC.sub.2, alloys such as CaSi, CaMg, CaFe, FeMn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide based on molybdenum, an oxide based on copper, an oxide based on zinc, a hydroxide based on molybdenum, a hydroxide based on copper, a hydroxide based on zinc and their mixture, at a content equal or greater to 1 weight % based on the total weight of the composition, c) mixing said particles and the second compound until an homogeneous composition is reached, d) providing said homogeneous composition in a confinement space between two punches having a section comprised between 1 and 40 cm.sup.2, e) compacting said homogeneous composition for forming a compact product with a three-dimensional shape, by applying a compaction pressure comprising 200 MPa and 800 MPa, f) releasing the compaction pressure and g) ejecting said compact product from said confinement space.

21. The method according to claim 20, wherein said second compound is selected from the group consisting of B.sub.2O.sub.3, NaO.sub.3, metal Al, metal Mg, metal Fe, metal Mn, metal Mo, metal Zn, metal Cu, elemental Si, CaC.sub.2, alloys such as CaSi, CaMg, CaFe, FeMn, FeSi, FeSiMn, FeMo; TiO.sub.2, an oxide based on molybdenum, an oxide based on copper, an oxide based on zinc, a hydroxide based on molybdenum, a hydroxide based on copper, a hydroxide based on zinc and their mixture and is comprised into the composition at a content equal to or lower than 20 weight % based on the total weight of the composition.

22. The method according to claim 20, wherein said second compound is chosen in the group consisting of CaF.sub.2, calcium ferrites selected from thegroup consisting of Ca.sub.2Fe.sub.2O.sub.5 or CaFe.sub.2O and their mixture and is comprised into the composition at a content equal to or lower than 40 weight %, based on the total weight of the composition.

23. The method according to claim 20, wherein said second compound is selected from the group consisting of calcium illuminate, calcium silicate, carbon and their mixture and is comprised into the composition at a content equal to or lower than 60 weight % based on the total weight of the composition.

24. The method according to claim 20, comprising a further step of adding, a third compound chosen in the group consisting of an organic additive selected from the group consisting of a binder, a lubricant and their mixture, an oxide selected from the group consisting of an oxide based on aluminum, an oxide based on silicon, an oxide based on iron, an oxide based on manganese, and their mixture, a hydroxide chosen in the group consisting of a hydroxide based on aluminum, a hydroxide based on silicon, a hydroxide based on iron, a hydroxide based on manganese and their mixture, said third compound having a hardness greater than or equal to 5 on the Mohs scale, and a size of particles d.sub.100 of less than or equal to 200 m before said step of providing said homogeneous composition in a confinement space d).

25. The method according to claim 20, wherein said space confined between said two punches is lubricated beforehand by means of a lubrication step during which a lubricant in the form of a powder, said powder being selected from the group consisting of calcium or magnesium stearate, is deposited at the surface of said space confined between said two punches, said lubricant in the form of a powder being compacted with the particles of the composition of particles and represents advantageously between 0.01 and 0.3% by weight based on the total weight of the compact product.

26. The method according to claim 20, wherein said collected compact product is then thermally treated between 700 C. and 1200 C. for a predetermined time period comprised between 1 and 90 minutes.

27. The method according to claim 20, further comprising a step for surface treatment of said collected compact product, optionally after thermal treatment if it is present, at a temperature greater than or equal to 50 C., and less than or equal to 700 C., for a time period comprising between 5 and 60 minutes under a flow of gas containing CO.sub.2 and steam.

28. A method for making a composite material comprising several successive layers in order to form a multi-layer structure wherein at least one layer is formed with said compact product of the composition by the method according to claim 20 and further comprising an additional compaction step for said at least one layer of said compact product and fur another compact layer before said ejection step.

29. (canceled)

Description

EXAMPLE

Example 1

[0146] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, provided with standard blade of a radius of 7 cm rotating at 350 rpm (i.e. 2.6 m/s). This mixer is used in a continuous mode to prepare a mixture comprising 85 weight % of quicklime fines 0-3 mm and 15 weight % of CaF.sub.2 powder (fluospar CaF.sub.2) 0-6 mm. The total flow rate of the powder is 300 kg/h and the residence time is 3.5 s. The resulting mixture is very homogeneous, meaning that the amount of CaF.sub.2 for different samples of 10 g withdrawn in the final mixture is each time comprised between 14 and 16 weight % based on the total weight of the composition.

[0147] A rotary press Eurotab of the Titan type is used. Such rotary press comprises a die having an internal wall defining at least said confinement space having a section which is reducing downwards. The lower section of the confinement space accommodating the compact is lower than the upper section of the confinement space accommodating the compact, for facilitating the ejection of the compact from the confinement space, and offers a productivity of at least 100 cpm (compacts per minute). Starting with about thirty kilograms of slaked lime fines of 0-3 mm, 12.7 g of this mixture are successively poured into each of the dies of the tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and with a diameter of about 21 mm. Compression is carried out under a compression of 500 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 100 ms.

[0148] Several kilograms of substantially cylindrical compacts each having a weight of 12.6 g and a median diameter of a mean value of 21.4 mm are obtained. The upper diameter of the upper (top) part of the compacts has a mean value of 21.51 mm and the lower diameter of the lower part (bottom) of the compacts has a mean value of 21.29 mm, leading respectively to an upper surface of the upper part with a mean value of 363 mm.sup.2 and to a lower surface of the lower part with a mean value of 356 mm.sup.2. By consequence, the difference between the mean upper surface and the mean lower surface of said compacts reported to the mean median section of the compact is equal to 2.06% [(mean upper surface of the upper part-lower surface of the lower part)/median section of the compact]. The height is 15.9 mm and the density is 2.20 g/cm.sup.3. These compacts are of a homogeneous quality and are free from macroscopic defects.

[0149] These compacts develop a specific BET surface area (as measured by manometry with adsorption of nitrogen after degassing in vacuo at 190 C. for at least two hours and calculated according to the multipoint BET method as described in the ISO 9277:2010E standard) of 1.8 m.sup.2/g and have a total mercury pore volume of 34% (as determined by porosimetry by introduction of mercury according to part 1 of the ISO 15901-1:2005E standard which consists of dividing the difference between the skeleton density, measured at 30000 psia, and the apparent density, measured at 0.51 psia, by the skeleton density).

[0150] A Shatter Test is performed starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm, generated at the end of these 4 falls is weighed. A Shatter Test Index of 2.8% is obtained.

Example 2

[0151] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, provided with standard blade of a radius of 7 cm rotating at 350 rpm (i.e. 2.6 m/s). This mixer is used in a continuous mode to prepare a mixture comprising 85 weight % of quicklime fines 0-3 mm and 15 weight % of CaF.sub.2 powder (fluospar CaF.sub.2) 0-6 mm. The total flow rate of the powder is 300 kg/h and the residence time is 3.5 s. The resulting mixture is very homogeneous, meaning that the amount of CaF.sub.2 for different samples of 10 g withdrawn in the final mixture is each time comprised between 14 and 16 weight % based on the total weight of the composition.

[0152] A rotary press Eurotab of the Titan type as described in example 1 is used. Starting with about thirty kilograms of slaked lime fines of 0-3 mm, 12.7 g of this mixture are successively poured into each of the dies of tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and with a diameter of about 21 mm. Compression is carried out under a compression of 430 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 100 ms.

[0153] Several kilograms of substantially cylindrical compacts each having a weight of 12.6 g and median diameter having a mean value of 21.5 mm are obtained. The height is 17.4 mm and the density is 2.1 g/cm.sup.3. These compacts are of a homogeneous quality and are free from macroscopic defects.

[0154] These compacts develop a specific BET surface area (as measured by manometry with adsorption of nitrogen after degassing in vacuo at 190 C. for at least two hours and calculated according to the multipoint BET method as described in the ISO 9277:2010E standard) of 1.6 m.sup.2/g and have a total mercury pore volume of 42% (as determined by porosimetry by introduction of mercury according to part 1 of the ISO 15901-1:2005E standard which consists of dividing the difference between the skeleton density, measured at 30000 psia, and the apparent density, measured at 0.51 psia, by the skeleton density).

[0155] A Shatter Test is performed starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm, generated at the end of these 4 falls is weighed. A Shatter Test Index of 7.9% is obtained.

Example 3

[0156] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, provided with standard blade of a radius of 7 cm rotating at 350 rpm (i.e. 2.6 m/s). This mixer is used in a continuous mode to prepare a mixture comprising 70 weight % of quicklime fines 0-3 mm and 30 weight % of CaF.sub.2 powder (fluospar CaF.sub.2) 0-6 mm. The total flow rate of the powder is 300 kg/h and the residence time is 3.5 s. The resulting mixture is very homogeneous, meaning that the amount of CaF.sub.2 for different samples of 10 g withdrawn in the final mixture is each time comprised between 28 and 32 weight % based on the total weight of the composition.

[0157] A rotary press Eurotab of the Titan type as described in example 1 is used. Starting with about thirty kilograms of a mixture consisting of 50% of slaked lime fines of 0-3mm and of 50% of slaked dolime fines of 0-3 mm, 12.5 g of this mixture are successively poured in each of the dies of the tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and a diameter of about 21 mm. Compression is performed under a pressure of 590 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 105 ms.

[0158] Several kilograms of compacts each having a weight of 12.5 g and a median diameter having a mean value of 21.4 mm are obtained. The height is 15.6 mm and the density is 2.32 g/cm.sup.3. These compacts have homogeneous quality and are free of macroscopic defects.

[0159] These compacts develop a BET specific surface area of 1.5 m.sup.2/g and have a total mercury pore volume of 35%.

[0160] A Shatter Test is conducted starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm generated at the end of these 4 falls is weighed. A Shatter Test Index of 5.2% is obtained.

Example 4

[0161] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, provided with standard blade of a radius of 7 cm rotating at 350 rpm (i.e. 2.6 m/s). This mixer is used in a continuous mode to prepare a mixture comprising 70 weight % of quicklime fines 0-3 mm and 30 weight % of CaF.sub.2 powder (fluospar CaF.sub.2) 0-6 mm.

[0162] The total flow rate of the powder is 300 kg/h and the residence time is 3.5 s. The resulting mixture is very homogeneous, meaning that the amount of CaF.sub.2 for different samples of 10 g withdrawn in the final mixture is each time comprised between 28 and 32 weight % based on the total weight of the composition.

[0163] A rotary press Eurotab of the Titan type as described in example 1 is used. Starting with about thirty kilograms of slaked lime fines of 0-3 mm, 9.4 g of these fines are successively poured in each of the dies of the tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and a diameter of about 21 mm. Compression is performed under a pressure of 480 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 100 ms.

[0164] Several kilograms of compacts are obtained, each having a weight of 13.5 g and an average dimension (median diameter) of 21.3 mm are obtained. The height is 17.85 mm and the density is 2.1 g/cm.sup.3.

[0165] These compacts develop a BET specific surface area of 1.3 m.sup.2/g and have a total mercury pore volume of 40%.

[0166] A Shatter Test is conducted starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm generated at the end of these 4 falls is weighed. A Shatter Test Index of 8.5% is obtained.

Example 5

[0167] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, equipped with standard blades with a radius of 7 cm, used in rotation at 350 revolutions per minute (i.e. 2.6 m/s). This mixer is used in a continuous mode in order to prepare a mixture consisting of 89.75% by weight of slaked lime fines of 0-3 mm and of 10.25% by weight of a mixture of carbon (Blaskohle Luxcarbon 97 DCE 0-2 mm) and glycerol (97.5 weight % of carbon and 2.5 weight % of glycerol). The total flow rate of the powder is 300 kg/h and the dwelling time is 3.5 s. The obtained mixture is very homogeneous. This means that the carbon content for different 10 g samples taken from the final mixture is always comprised between 9 and 11% (+/10% relatively).

[0168] A rotary press Eurotab of the Titan type as described in example 1 is used. Starting with about thirty kilograms of the mixture, 12.8 g of this mixture are successively poured into each of the dies of the tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and a diameter of about 21 mm. Compression is performed under a pressure of 500 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 105 ms.

[0169] Several kilograms of compacts each having a weight of 12.8 g and a mean median diameter of 21.4 mm are obtained. The upper diameter of the upper (top) part of the compacts has a mean value of 21.48 mm and the lower diameter of the lower part (bottom) of the compacts has a mean value of 21.32 mm, leading respectively to an upper surface of the upper part with a mean value of 362 mm.sup.2 and to a lower surface of the lower part with a mean value of 357 mm.sup.2. By consequence, the difference between the mean upper surface and the mean lower surface of said compacts reported to the mean median section of the compact is equal to 1.50% [(mean upper surface of the upper part-lower surface of the lower part)/median section of the compact].The height is 16.4 mm and the density is 2.25 g/cm.sup.3. These compacts have homogeneous quality and are free from macroscopic defects.

[0170] A Shatter Test is conducted starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm generated at the end of these 4 falls is weighed. A Shatter Test Index of 5.0% is obtained.

Example 6

[0171] A powder mixer Gericke GCM450 is used with a capacity of 10 dm.sup.3, equipped with standard blades with a radius of 7 cm, used in rotation at 350 revolutions per minute (i.e. 2.6 m/s). This mixer is used in a continuous mode in order to prepare a mixture consisting of 45% by weight of slaked lime fines of 0-3 mm, of 15% by weight of metal Al 0-200 m, of 30 weight % of Al.sub.2O.sub.3 (0-3 mm) and of 10 weight % slaked lime. The total flow rate of the powder is 300 kg/h and the dwelling time is 3.5 s. The obtained mixture is very homogeneous. This means that the content in aluminum compound (metal Al or Al.sub.2O.sub.3) for different 10 g samples taken from the final mixture is always comprised between 13 and 17% and 28% and 32% (+/10% relatively).

[0172] A rotary press Eurotab of the Titan type as described in example 1 is used. 12.8 g of the mixture are successively poured into each of the dies of the tooling with a substantially cylindrical shape having a section reducing downwards for the compact portion and a diameter of about 21 mm. Compression is performed under a pressure of 470 MPa, with a closing-in speed of the punches of 115 mm/s and a maintaining time of 105 ms.

[0173] Several kilograms of cylindrical compacts each having a weight of 12.8 g and a median diameter of 21.2 mm are obtained. The height is 16.4 mm and the density is 2.25 g/cm.sup.3. These compacts have homogeneous quality and are free from macroscopic defects.

[0174] These compacts develop a BET specific surface area of 4.8 m.sup.2/g and have a total mercury pore volume of 37%.

[0175] A Shatter Test is conducted starting with 0.5 kg of these compacts by successively performing 4 two-meter falls. The amount of fines of less than 10 mm generated at the end of these 4 falls is weighed. A Shatter Test Index of 3.0% is obtained.

[0176] It is obvious that the present invention is by no means limited to the embodiments described above and that many modifications may be provided thereto without departing from the scope of the appended claims.