Pulverulent compositions of a complex between an acid and a metal having a high organosulfur compound content and method for preparing same

Abstract

Disclosed are pulverulent compositions of a complex between an acid and a metal, having a high organosulfur compound content, and method for preparing same.

Claims

1. A particle comprising: a core consisting essentially of a salt of formula (I) below:
(A.sup.).sub.nM.sup.n+(I) in which: A.sup. represents an anion chosen from the group consisting of 2-hydroxy-4-methylthiobutanoate, methioniate and cysteinate, M represents a divalent or trivalent metal, n being equal to 2 when said metal is divalent and to 3 when said metal is trivalent, and a layer comprising a compound B chosen from the group consisting of 2-hydroxy-4-methylthiobutanoic acid (HMTBA), methionine, cysteine, mixtures thereof, salts thereof and complexes thereof, said layer coating said core, the weight percentage of said compound B relative to the salt of formula (I) of the core being from approximately 10% to approximately 50%, said compound B not being, or not only being, in the form of a salt of formula (I), the organosulfur compound content (TOS) of said particle being greater than 87% by weight relative to the total weight of said particle.

2. A particle according to claim 1, wherein said compound B is in the: free form, chosen from 2-hydroxy-4-methylthiobutanoic acid (HMTBA), methionine and cysteine, and/or form of salt of said formula (I), and/or form of a complex of formula (A).sub.4M (II) in which A and M are as defined, said compound B not being, or not only being, in the form of a salt of formula (I), said compound B being in the: free form, form of the complex of formula (II), form of a mixture of the free form and of the complex of formula (II), form of a mixture of the free form and of the salt of formula (I), form of a mixture of the salt of formula (I) and of the complex of formula (II), or form of a mixture of the free form, of the salt of formula (I) and of the complex of formula (II).

3. A particle according to claim 1, wherein: the water content is less than 3% by weight of the particle, the calcium content is from 6% to 11% by weight of the particle, or the weight percentage of said compound B relative to the salt of formula (I) of the core is from approximately 10% to approximately 40%.

4. A particle according to claim 1 wherein said metal is selected from the group consisting of Mg, Be, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Pt, B, Al, Ga, and In, and said salt of formula (I) is selected from the group consisting of (HMTBA).sub.2Ca, (HMTBA).sub.2Mg, (HMTBA).sub.2Fe, (HMTBA).sub.2Mn, (HMTBA).sub.2Zn, (HMTBA).sub.2Cu, (HMTBA).sub.3Fe, (HMTBA).sub.3Al, (Methionine).sub.2Ca, (Methionine).sub.2Mg, (Methionine).sub.2Fe, (Methionine).sub.2Mn, (Methionine).sub.2Zn, (Methionine).sub.2Cu, (Methionine).sub.3Fe, (Methionine).sub.3Al, (Cysteine).sub.2Ca, (Cysteine).sub.2Mg, (Cysteine).sub.2Fe, (Cysteine).sub.2Mn, (Cysteine).sub.2Zn, (Cysteine).sub.2Cu, (Cysteine).sub.3Fe, and (Cysteine).sub.3Al.

5. A particle according to claim 1, wherein: said anion A.sup. is 2-hydroxy-4-methylthiobutanoate, and/or said compound B included in said layer is 2-hydroxy-4-methylthiobutanoic acid (HMTBA), or a salt or complex thereof.

6. A pulverulent composition consisting of or comprising particles according to claim 1.

7. A pulverulent composition of particles according to claim 6, wherein the particle size of said particles ranges from 10 to 3000 m [Dv(0,5)].

8. A pulverulent composition according to claim 6, in which: the bulk density is greater than 350 g/L, or the tapped density is greater than 400 g/L.

9. A pulverulent composition according to claim 6, comprising oil in addition to said particles.

10. A process for producing a particle comprising: a core consisting essentially of a salt of formula (I) below:
(A.sup.).sub.nM.sup.n+(I) in which: A.sup. represents an anion chosen from the group consisting of 2-hydroxy-4-methylthiobutanoate, methioniate and cysteinate, M represents a divalent or trivalent metal, n being equal to 2 when said metal is divalent and to 3 when said metal is trivalent, and a layer comprising a compound B chosen from the group consisting of 2-hydroxy-4-methylthiobutanoic acid (HMTBA), methionine and cysteine, said layer coating said core, the weight percentage of said compound B relative to the salt of formula (I) of the core being from approximately 10% to approximately 50%, said compound B not being, or not only being, in the form of a salt of formula (I), the organosulfur compound content (TOS) of said particle being greater than 87% by weight relative to the total weight of said particle, said process comprising a step of spraying, onto a solid consisting essentially of a salt of formula (I) as defined above, a composition comprising a compound B chosen from the group consisting of 2-hydroxy-4-methylthiobutanoic acid (HMTBA), methionine and cysteine, the weight of said compound B being from approximately 10% to approximately 50% of the weight of the salt of formula (I) of the solid, in order to obtain said particle.

11. A process according to claim 10, wherein said spraying step is carried out: batchwise or continuously in a fluidized airbed, or on a vibro-fluidizer, or in a spray tower by co-spraying.

12. A process according to claim 10, wherein the core consisting essentially of a salt of formula (I) is obtained: by reactive atomization, in a fluidized airbed, in a granulator, in a rotary granulator, or in a mixer, by a reactive extrusion, or by means of a static or dynamic mixer.

13. The particle of claim 4, wherein the salt of formula (I) is a salt of formula (HMTBA).sub.2Ca, (HMTBA).sub.2Mg, (HMTBA).sub.2Fe, (HMTBA).sub.2Mn, (HMTBA).sub.2Zn, (HMTBA).sub.2Cu, (Methionine).sub.2Ca, (Methionine).sub.2Mg, (Methionine).sub.2Fe, (Methionine).sub.2Mn, (Methionine).sub.2Zn, (Methionine).sub.2Cu, (Cysteine).sub.2Ca, (Cysteine).sub.2Mg, (Cysteine).sub.2Fe, (Cysteine).sub.2Mn, (Cysteine).sub.2Zn or (Cysteine).sub.2Cu.

14. The particle of claim 2, wherein A represents 2-hydroxy-4-methylthiobutanoic acid (HMTBA).

15. The particle of claim 3, wherein the calcium content is from 6.5% to 10% by weight of the particle.

16. The particle of claim 3, wherein the calcium content is from 7% to 9% by weight of the particle.

17. The particle of claim 3, wherein the calcium content is approximately 8% by weight of the particle.

18. The particle of claim 3, wherein the weight percentage of said compound B relative to the salt of formula (I) of the core is from approximately 15% to approximately 35%.

19. The particle of claim 3, wherein the weight percentage of said compound B relative to the salt of formula (I) of the core is from approximately 20% to approximately 32%.

20. A particle according to claim 2, wherein said metal is selected from the group consisting of Mg, Be, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Pt, B, Al, Ga, and In and said salt of formula (I) is selected from the group consisting of (HMTBA).sub.2Ca, (HMTBA).sub.2Mg, (HMTBA).sub.2Fe, (HMTBA).sub.2Mn, (HMTBA).sub.2Zn, (HMTBA).sub.2Cu, (HMTBA).sub.3Fe, (HMTBA).sub.3Al, (Methionine).sub.2Ca, (Methionine).sub.2Mg, (Methionine).sub.2Fe, (Methionine).sub.2Mn, (Methionine).sub.2Zn, (Methionine).sub.2Cu, (Methionine).sub.3Fe, (Methionine).sub.3Al, (Cysteine).sub.2Ca, (Cysteine).sub.2Mg, (Cysteine).sub.2Fe, (Cysteine).sub.2Mn, (Cysteine).sub.2Zn, (Cysteine).sub.2Cu, (Cysteine).sub.3Fe, and (Cysteine).sub.3Al.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1A is an optical microscopy image relating to the powder obtained at the end of example 1.

(2) FIG. 1B is an optical microscopy image relating to the powder obtained at the end of example 12.

(3) FIG. 2A is a scanning optical microscopy image relating to the powder obtained at the end of example 1.

(4) FIG. 2B is a scanning optical microscopy image relating to the powder obtained at the end of example 12.

(5) FIG. 3A shows the X-ray analysis spectrum of powders of sample A between 2=1 and 2=24 obtained using a radiation MoK (=0.71073 ).

(6) FIG. 3B shows the X-ray analysis spectrum of powders of sample B between 2=1 and 2=24 obtained using a radiation MoK (=0.71073 ).

(7) FIG. 3C shows the X-ray analysis spectrum of powders of sample C between 2=1 and 2=24 obtained using a radiation MoK (=0.71073 ).

(8) Sample A corresponds to the powder of salt of formula (I) (HMTBA).sub.2Ca obtained in the first part of example 9.

(9) Sample B corresponds to the powder obtained at the end of example 1.

(10) Sample C corresponds to the powder obtained at the end of example 12.

(11) FIG. 4 represents scanning electron microscope (SEM) analysis coupled to X-ray emission spectrometry, carried out at the core (A) and at the surface (B) of one and the same particle according to example 3.

(12) FIG. 5 is a diagram of principle of a process according to the invention, carried out in a multiple effect tower.

(13) An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 130 and feeds, via a pump 131, the contacting device 134. An aqueous medium containing a metal or metal cation symbolized by the circle B optionally passes through a heater 132 and feeds, via a pump 133, the contacting device 134. The aqueous phase resulting from the mixing between the aqueous medium A and the aqueous medium B is sprayed in the spray tower via the spray device 104 intended for the production of monodisperse or polydisperse aerosols.

(14) An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 144 and feeds, via a pump 145 the spraying device 147 intended for the production of aerosols.

(15) An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 151 and feeds, via a pump 152 the spraying device 148 intended for the production of aerosols.

(16) The circle C represents an additional device for spraying anti-agglomerating agent via a powder-metering device 136, if necessary.

(17) The circle D represents the introduction of the hot vector gas, in particular air and/or inert gas, in the spray-drying version, via the fan 124.

(18) The circle E represents the introduction of the secondary vector gas, for the drying and/or the final cooling of the stabilized final composition obtained, which is solid or undergoing solidification, via a fan 137.

(19) The circle J represents the introduction of the vector gas onto the external vibrated fluidized bed 139, for the drying and/or the final cooling of the stabilized final composition obtained, which is solid or undergoing solidification via the fan 146.

(20) A cyclone 138 separates all or some of the final product F that is to say the pulverulent composition, which is recovered, and the vector gas G which is discharged.

(21) The external vibrated fluidized bed 139 allows the recovery of all or some of the final product H, that is to say the pulverulent composition, via the bottom of the tower.

(22) The introduction of the secondary air E takes place through a permeable base 142 of the tower 135 in order to place the powder material in fluidized bed form. The spent air is discharged via one or more orifice(s) 143 made through the upper wall of the chamber 101.

(23) The introduction of the secondary air J takes place through a permeable base 149 of the vibrated fluidized bed 139 in order to place the powder material in fluidized bed form. The spent air is discharged via the line 150 connected to the inlet of the cyclone 138.

(24) In this example, the spent air then passes through the cyclone 138 which produces, on the one hand, particles of product F and, on the other, air to be discharged G. Most of the particles are collected just above the permeable wall 142. FIG. 1 illustrates that the particles are collected either directly in F, or by means of the external fluidized bed 139 in H.

(25) It is also possible to envision the addition, represented by the circle I, in the spray zone, of a powdered substance, in particular fine particles of the pulverulent composition recovered at the outlet of the cyclone 138, product F, or the installation, injected by means of the device 141 consisting mainly of a powder-metering device.

(26) FIG. 6 is a diagram of the principle of a process according to the invention, carried out in a multiple effect tower and as described in FIG. 5, with A=A=A.

(27) FIG. 7 is a diagram of the principle of a process according to the invention, carried out in a multiple effect tower.

(28) An aqueous medium containing an acid, symbolized by the circle A is transferred into a reactor C equipped with a thermostatic jacket 161. An aqueous medium containing a metal or metal cation symbolized by the circle B is gradually added to the reactor C with stirring. The aqueous phase K resulting from the mixing between the aqueous medium A and the aqueous medium B, is fed, via the conveying pump 162 in order to be sprayed in the spray tower via the spraying device 104 intended for the production of monodisperse or polydisperse aerosols.

(29) An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 144 and feeds, via a pump 145 the spraying device 147 intended for the production of aerosols.

(30) An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 151 and feeds, via a pump 152 the spraying device 148 intended for the production of aerosols.

(31) The circle C represents an additional device for spraying anti-agglomerating agent via a powder-metering device 136, if necessary.

(32) The circle D represents the introduction of the hot vector gas, in particular air and/or inert gas, in the spray-drying version, via the fan 124.

(33) The circle E represents the introduction of the secondary vector gas, for the drying and/or the final cooling of the stabilized final composition obtained, which is solid or undergoing solidification, via a fan 137.

(34) The circle J represents the introduction of the vector gas onto the external vibrated fluidized bed 139, for the drying and/or the final cooling of the stabilized final composition obtained, which is solid or undergoing solidification via the fan 146.

(35) A cyclone 138 separates all or some of the final product F that is to say the pulverulent composition, which is recovered, and the vector gas G which is discharged.

(36) The external vibrated fluidized bed 139 allows the recovery of all or some of the final product H, that is to say the pulverulent composition, via the bottom of the tower.

(37) The introduction of the secondary air E takes place through a permeable base 142 of the tower 135 in order to place the powder material in fluidized bed form. The spent air is discharged via an orifice 143 made through the upper wall of the chamber 101.

(38) The introduction of the secondary air J takes place through a permeable base 149 of the vibrated fluidized bed 139 in order to place the powder material in fluidized bed form. The spent air is discharged via the line 150 connected to the inlet of the cyclone 138.

(39) In this example, the spent air then passes through the cyclone 138 which produces, on the one hand, particles of product F and, on the other, air to be discharged G. Most of the particles are collected just above the permeable wall 142. FIG. 1 illustrates that the particles are collected either directly in F, or by means of the external fluidized bed 139 in H.

(40) It is also possible to envision the addition, represented by the circle I, in the spray zone, of a powdered substance, in particular fine particles of the pulverulent composition that are recovered at the outlet of the cyclone 138, product F, or the installation, injected by means of the device 141 consisting mainly of a powder-metering device.

(41) FIG. 8 is a diagram of the principle of a process according to the invention, carried out in a fluidized airbed.

(42) A pulverulent composition of salt (HMTBA).sub.2Ca, symbolized by the circle B is incorporated into a fluidized airbed 170. An aqueous medium containing an acid, symbolized by the circle A, optionally passes through a heater 171 and feeds, via a pump 172 a spraying device 173 intended for the production of aerosols.

(43) The circle D represents the introduction of the vector gas, for the drying and/or the final cooling of the stabilized final composition obtained, which is solid or undergoing solidification, via a fan 174.

(44) The introduction of the gas D takes place through a permeable base 175 of the fluidized bed in order to place the powder matter B in fluidized bed form. The spent air is discharged through one or more filter(s) via an orifice 176 made through the upper wall of the chamber 177.

(45) The final pulverulent composition H is recovered at the end of the batch during the emptying of the fluidized bed.

EXAMPLES

(46) Examples 1 to 12 which follow illustrate the invention.

Example 1: Production of a Powder Having a TOS of 88.3% by Weight

(47) One kilogram of salt (HMTBA).sub.2Ca at 85.5% of TOS, 11.7% of calcium and 2.3% moisture content was incorporated into a fluidized airbed having a working volume of 5 liters. 300 g of a solution of HMTBA at 88% of dry matter was sprayed onto this powder at a flow rate of 450 g/h, a spraying pressure of 1.5 bar and an input temperature on the fluidized airbed of 60 C. At the end of the spraying, the product was dried for 5 min.
The product obtained has a TOS of 88.3%, a calcium content of 9.2% and a moisture content of 1.3%. The mean particle size of this product is 191 m, the bulk density is 390 g/L and the tapped density is 480 g/L.

Example 2: Production of a Powder Having a TOS of 89.3% by Weight

(48) One kilogram of salt (HMTBA).sub.2Ca at 84.6% of TOS, 11.5% of calcium and 1.9% moisture content was incorporated into a fluidized airbed having a working volume of 5 liters. 504 g of a solution of HMTBA at 88% of dry matter were sprayed onto this powder at a flow rate of 250 g/H, a spraying pressure of 1.5 bar and an input temperature on the fluidized airbed of 60 C. At the end of the spraying, the product was dried for 5 min.
The product obtained has a TOS of 89.3%, a calcium content of 8% and a moisture content of 1.6%.

Example 3: Production of a Powder Having a 5.5TOS of 88.2% by Weight

(49) Two kilograms of salt (HMTBA).sub.2Ca at 85.5% of TOS, 11.7% of calcium and 2.3% of moisture content were incorporated into a fluidized airbed having a working volume of 12 liters. 670 g of a solution of HMTBA at 88% of dry matter were sprayed onto this powder at a flow rate of 600 g/H, a spraying pressure of 1 bar and a fluidized airbed input temperature of 55 C. At the end of the spraying, the product was dried for 5 min.
The product obtained has a TOS of 88.2%, a calcium content of 8.8%, and a moisture content of 2.2%. The mean particle size of this product is 150 m, the bulk density is 370 g/L, and the tapped density is 400 g/L.

Example 4: Production of a Powder Having a TOS of 88.1% by Weight

(50) A milling step on a knife mill is carried out on two kilograms of a salt (HMTBA).sub.2Ca in the form of extruded material obtained according to patent FR2964968. The powder obtained post-milling has a TOS of 74%, a calcium content of 11.2%, a water content of 11% and a means particle size of 150 m. One kilogram of this product is incorporated into a fluidized airbed having a working volume of 5 liters. 400 g of a solution of HMTBA at 88% of dry matter are then sprayed onto this powder at a flow rate of 300 g/H, a spraying pressure of 1.5 bar and a fluidized airbed input temperature of 60 C. The product is then dried for 30 min.
The product obtained has a TOS of 88.1%, a calcium content of 9.2%, and a moisture content of 1.4%. The mean particle size of this product is 250 m and the bulk density is 510 g/L.

Example 5: Production of a Powder Having a TOS of 88.4% by Weight

(51) One kilogram of salt (HMTBA).sub.2Ca at 85.5% of TOS, 11.7% of calcium and 2.3% of moisture content is incorporated into a fluidized airbed. 275 g of a solution of HMTBA at 95.47% of dry matter, heated to a temperature of 60 C. is sprayed onto this powder at a flow rate of 300 g/H, a spraying pressure of 1.5 bar and a fluidized airbed input temperature of 60 C. The product is then dried for 5 min.
The product obtained has a TOS of 88.4%, a calcium content of 8.9%, and a moisture content of 1.5%. The mean particle size of this product is 680 m, the bulk density is 380 g/L, and the tapped density is 410 g/L.

Example 5a: Production of a Powder Having a TOS of 88.2% by Weight

(52) Three kilograms of salt (HMTBA).sub.2Ca at 85.5% of TOS, 11.7% of calcium and 2.3% of moisture content are incorporated into a rotary granulator having a working volume of 5 liters of GLATT GRC3 type. 1 kg of a solution of HMTBA at 88% of dry matter is sprayed onto this powder at a flow rate 600 g/H, a spraying pressure of 1.5 bar, a granulator input temperature of 60 C. and disk rotation speed of 200 rom. The product is then dried for 5 min.
The product obtained has a TOS of 88.2%, a calcium content of 9.1% and a moisture content of 1.7%. The mean particle size of this product is 230 m and the bulk density is 540 g/L.

Example 6: Production of a Powder Having a TOS of 88.1% by Weight

(53) A powder of salt (HMTBA).sub.2Ca at 85.2% of TOS, 11.8% of calcium and 1.8% of moisture content was continuously fed into a multiple effect spray tower at a flow rate of 200 kg/H. A solution of HMTBA at 88% of dry matter was continuously sprayed in the bottom part of the spray tower. This solution was sprayed, on the one hand, onto the static bed of the industrial facility at a flow rate of 60 kg/h and a spraying pressure of 4 bar, and on the other hand, onto the vibro-fluidizer at a flow rate of 16 kg/H and a spraying pressure of 1.5 bar.
The temperature applied were 100 C. for the static bed temperature, 70 C. for the first part of the vibro-fluidizer and 30 C. for the second part of the vibro-fluidizer.
The product obtained has a TOS of 88.1%, a calcium content of 9.1%, and a moisture content of 1.4%. The mean particle size of this product is 196 m, the bulk density is 530 g/L and the tapped density at 10 taps is 560 g/L.

Example 7: Production of a Powder Having a TOS of 88.5% by Weight

(54) A powder of salt (HMTBA).sub.2Ca at 85.18% of TOS, 11.78% of calcium and 1.79% of moisture content is continuously fed into a multiple effect tower at a flow rate of 200 kg/H. A solution of HMTBA at 96% of dry matter, heated to a temperature of 60 C. so as to lower its viscosity below 200 centipoises, is continuously sprayed in the bottom part of the drying tower. This solution is sprayed, on the one hand, onto the static bed of the industrial installation at a flow rate of 48 kg/h and a spraying pressure of 3.5 bar, and on the other hand, onto the vibro-fluidizer at a flow rate of 13 kg/H and a spraying pressure of 1.5 bar.
The temperatures of the liquid feed lines are thermostated at 60 C. so as to ensure satisfactory spraying of the concentrated HMTBA solution.
The temperatures applied are 100 C. for the static bed temperature, 70 C. for the first part of the vibro-fluidizer and 30 C. for the second part of the vibro-fluidizer.
The product obtained has a TOS of 88.5%, a calcium content of 8.8%, and a moisture content of 1.3%. The mean particle size of this product is 250 m and the bulk density is 550 g/L.

Example 8: Production of a Powder Having a TOS of 88.3% by Weight

(55) A lime milk produced at 30% of dry matter and a solution of HMTBA at 88% of dry matter are continuously mixed according to the conditions of patent FR2988091.

(56) The feed flow rates are respectively 95 kg/H for the lime milk and 130 kg/H for the HMTBA solution.

(57) The reaction mixture is sprayed by means of a nozzle according to the knowledge of those skilled in the art, in a multiple effect spray tower with an input temperature of 180 C. and an output temperature of 102 C.

(58) At the bottom of the tower, a solution of HMTBA at 88% of EST is sprayed, on the one hand, onto the static bed of the MSD tower at a flow rate of 35 kg/h and a spraying pressure of 3 bar, and on the other hand, onto the vibro-fluidizer at a flow rate of 10 kg/H and a spraying pressure of 1.5 bar.
The temperatures applied are 70 C. for the static bed temperature, 60 C. for the first part of the vibro-fluidizer and 30 C. for the second part of the vibro-fluidizer.
The product obtained has a TOS of 88.3%, a calcium content of 8.9%, and a moisture content of 1.6%. The mean particle size of this product is 180 m and the bulk density is 420 g/L.

Example 9: Production of a Powder Having a TOS of 88.6% by Weight

(59) A lime milk produced at 30% of dry matter and a solution of HMTBA at 88% of dry matter are continuously mixed in an atomization turbine (of NIRO Atomizer type). The feed flow rates were respectively 3.5 kg/H for the lime milk and 4.5 kg/H for the HMTBA solution.
The reaction mixture was atomized in a single effect spray tower at an input temperature of 140 C. and an output temperature of 85 C.
The product was then taken up in a fluidized airbed in order to simulate a multiple effect tower.
330 g of a solution of HMTBA at 88% of dry matter were sprayed onto 1 kg of previously produced powder at a flow rate of 300 g/H, a spraying pressure of 1.5 bar and a fluidized airbed input temperature of 60 C. At the end of the spraying, the product was dried for 5 min.

(60) The product obtained has a TOS of 88.6%, a calcium content of 8.7% and a moisture content of 1.5%.

Example 10: Production of a Powder Having a TOS of 88.6% by Weight

(61) A lime milk produced at 37% of dry matter and a solution of HMTBA at 88% of dry matter are continuously mixed according to the conditions of patent FR2988091.

(62) The feed flow rates are respectively 90 kg/H for the lime milk and 150 kg/H for the HMTBA solution.

(63) The mixture is sprayed by means of a nozzle according to the knowledge of those skilled in the art in a multiple effect spray tower with an input temperature of 180 C. and an output temperature of 105 C.

(64) At the bottom of the tower, a concentrated solution of HMTBA at 96% of dry matter is sprayed, on the one hand, onto the static bed of the MSD tower at a flow rate of 31 kg/h and a spraying pressure of 3 bar, and on the other hand, onto the vibro-fluidizer at a flow rate of 16 kg/H and a spraying pressure of 1.5 bar.
The temperatures of the liquid feed lines are thermostated at 60 C.
The temperatures applied are 70 C. for the static bed temperature, 60 C. for the first part of the vibro-fluidizer and 30 C. for the second part of the vibro-fluidizer.
The product obtained has a TOS of 88.6%, a calcium content of 8.7%, and a moisture content of 1.3%. The mean particle size of this product is 210 m and the bulk density is 430 g/L.

Example 11: Production of a Powder Having a TOS of 88.2% by Weight

(65) A lime milk produced at 30% of dry matter and a solution of HMTBA at 88% of dry matter are continuously mixed according to the conditions of patent FR2988091.

(66) The feed flow rates are respectively 75 kg/H for the lime milk and 102 kg/H for the HMTBA solution.

(67) The reaction mixture is sprayed by means of a nozzle according to the knowledge of those skilled in the art, in a multiple effect spray tower with an input temperature of 160 C. and an output temperature of 85 C. The drying is carried out under nitrogen in a tower equipped with a closed-circuit gas recycling system.
At the bottom of the tower, a solution of HMTBA at 88% of EST is sprayed, on the one hand, onto the static bed of the MSD at a flow rate of 20 kg/h and a spraying pressure of 3 bar, and on the other hand, onto the vibro-fluidizer at a flow rate of 15 kg/H and a spraying pressure of 1.5 bar.
The temperatures applied are 60 C. for the static bed temperature, 50 C. for the first part of the vibro-fluidizer and 20 C. for the second part of the vibro-fluidizer.
The product obtained has a TOS of 88.2%, a calcium content of 9%, and a moisture content of 1%. The mean particle size of this product is 240 m and the bulk density is 480 g/L.

Example 12

(68) Production of a Powder Comprising HMTBA According to A process not Belonging to the Present Invention, and Comparison of the Product Obtained with the Product According to the Invention.

(69) The production is carried out batchwise in a Z-arm mixer open to the atmosphere.

(70) 372 g of a crystalline HMTBA.sub.2(Ca) powder were incorporated into the mixer and then heated to 85 C. by means of the jacket of the equipment.

(71) A solution of HMTBA at 88% of dry matter was added four times, and at intervals of 15 min, to the operating mixer. The amounts added were 93 g, 92 g, 94 g and 96 g. At the end of the final addition, the preparation was kept stirring for 37 min at a temperature of 73-82 C. The paste recovered then underwent a drying operation for 24 h in the oven at 70 C.
The product obtained post-drying was then milled so as to obtain coarse particles.
A comparative analysis of the products produced according to example 12 and according to example 1 of the present application was carried out.
The table below indicates the physical and chemical properties of powders.

(72) TABLE-US-00001 Example 1 Example 12 (Process belonging to the (Process not belonging to present invention) the present invention) Physical properties Particle size, Product with homogeneous Product with heterogeneous m particle size Gaussian particle size with Curve with a median at agglomerates which approximately 200 m are a few mm to several tens of cm Bulk density, 370 680 g/l Chemical properties Moisture 1.5 1 content, % Calcium, % 10.1 9.4 TOS, % 88.4 89.9
These results very clearly indicate a significant difference with regard to the physical properties of these powders. Example 12 results in the obtaining of granules that are heterogeneous in size with a density >650 g/l, whereas example 1 of the present application results in the obtaining of a powder that is homogeneous in size with a density close to 400 g/l.
Other analyses make it possible to distinguish the two types of products. Thus, the visual appearance of the powders was studied under an optical microscope (FIG. 1) and under a scanning optical microscope (FIG. 2).
The particles produced according to example 1 are small spherical particles, with quite a narrow particle size distribution, and cream in color.
The particles of example 12 are compact aggregates which may be angular, heterogeneous in size and shape, brown in color and with a smooth surface appearance.
The X-ray analysis also made it possible to demonstrate differences with regard to the degree of crystallinity of the particles obtained according to the process (FIG. 3), linked to the intensity of the peak at 2theta=9.
These results make it possible to propose a classification in increasing order of crystallinity
A<B<C.
Sample A corresponds to the powder of salt of formula (I) (HMTBA).sub.2Ca obtained in example 9, before spraying: it is the core of salt of formula (I) (HMTBA).sub.2Ca, without exterior layer.
Sample B corresponds to the powder obtained at the end of example 1.
Sample C corresponds to the powder obtained at the end of example 12.
Powder A (core of salt of formula (I) without exterior layer) and powder B (subject of the present invention), are thus less crystalline than powder C.

Example 13: SEM Analysis Coupled to X-Ray Emission Spectrometry of the Particles Obtained According to Example 3

(73) An SEM analysis coupled to X-ray emission spectrometry was carried out on a particle produced according to example 3 in such a way as to demonstrate the difference in chemical composition between the core and the exterior of the particle (FIG. 4). The interior quantification (FIG. 4A) is the following:

(74) TABLE-US-00002 Element % Weight % At C 44.11 62.47 O 17.88 19.01 S 22.58 11.98 Ca 15.42 6.54 Total 100.00 100.00
The S/Ca atomic ratio is, in the interior of the particle (in the core), approximately 1.8.
The exterior quantification (FIG. 4B) is the following:

(75) TABLE-US-00003 Element % Weight % At C 53.01 67.39 O 22.74 21.70 S 17.60 8.38 Ca 6.65 2.53 Total 100.00 100.00
The S/Ca atomic ratio is, on the exterior of the particle (at its surface), approximately 3.3. This analysis makes it possible to demonstrate a difference in chemical composition between the core of the particle and the exterior of the particle, in particular with regard to the calcium percentage.
The theoretical chemical composition of the salt of formula (I) (HMTBA).sub.2Ca and of the complex of formula (II) (HMTBA).sub.4Ca is the following:
Form salt of formula (I)=338 g/mol

(76) TABLE-US-00004 Total % relative to molecular molecular weight of the molecule in Atoms Numbers weight, g/mol question Carbon 10 120 35.5 Oxygen 6 96 28.4 Sulfur 2 64 18.9 Hydrogen 18 18 5.32 Calcium 1 40 11.8
The S/Ca theoretical atomic ratio is, for the salt of formula (I), approximately 1.6.
Form complex of formula (II)=636 g/mol

(77) TABLE-US-00005 Total % relative to molecular molecular weight of the molecule in Atoms Numbers weight, g/mol question Carbon 20 240 37.7 Oxygen 12 192 30.1 Sulfur 4 128 20.1 Hydrogen 36 36 5.6 Calcium 1 40 6.28
The S/Ca theoretical atomic ratio is, for the salt of formula (I), approximately 3.2.
The comparison between the theoretical values and the measured values with regard to the % of sulfur and the calcium indicates the presence of a salt of formula (I) of HMBTA on the inside of the particle and of a complex of formula (II) on the outside.