NL8000220A - DEFLUORATED CALCIUM PHOSPHATE AND METHOD FOR THE PREPARATION THEREOF. - Google Patents

Description

,, 1 VO 881k

Defluorinated calcium phosphate and process for its preparation.

The invention relates to a new quality of defluorinated calcium phosphate for animal nutrition and to a process for its preparation.

Defluorinated calcium phosphates are important industrial products, which are used as a complement to animal feeds or as an important component of these complements in addition to nitrogenous derivatives, sugars, trace elements and vitamins.

A first technique for preparing de-fluorinated calcium phosphate, which has long been used by the applicant, consists in neutralizing a defluorinated phosphoric acid, ie either a phosphoric acid obtained by thermal means or a purified acid from the wet way by a calcium compound, such as finely divided lime, calcium carbonate or calcium chloride. The product obtained, which is a mixture of bi- and monocalcium phosphate, is almost colorless and is very well suited as animal feed, but it has the great disadvantage that it is expensive.

Another technique for preparing defluorinated calcium phosphates consists in thermally treating a natural phosphate generally in the presence of additives necessary to promote defluorination and obtain a product assimilated by the animals.

The phosphates obtained by this technique have the technical disadvantage that they are strongly colored and because of this fact, the manufacturers of animal feed complements disapprove of them in favor of the phosphates prepared by the wet route.

Furthermore, the thermally defluorinated phosphates, which are currently available on the market, do not at the same time have the whole of properties of phosphates along the wet road.

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Therefore, there was a need for a defluorinated natural calcium phosphate, which could be used as animal feed in the same manner as calcium phosphates obtained from the wet road.

A quality has now been found for thermally obtained calcium phosphate, which specifically meets the requirements imposed by the animal feed. This calcium phosphate is characterized by below properties: P total 15-21 wt. $ 10 F. <0.2 $

Approx. $ 25

After 6 - 10 $

Ash <6 10 ppm

Crystalline fane Na ^ Ca ^ (PO ^) ,. > 70 $ 15 Crystalline phase apatite <1 $

Crystalline phase Ca ^ (? 0 ^) 2 3 <5%

Solubility in citric acid)> 90 $

For the preparation of these phosphates, a process has been developed which, compared to the known techniques, has the double advantage that all the currently available natural calcium phosphates can be used as starting material, even those which are less rich in PgO4, such as <3-e. Algerian phosphates with 28.5% PgO 2 and lead to an excellent thermal balance, corresponding to a use of defluorinated phosphate obtained on the order of 80 - 100 kg / ton of heavy fuel oil No. 2 of the order of 80 - 100 kg / ton, while the known Applicants' methods it is normal to use twice as much fuel.

One of the special advantages of this technique is that it is possible to use phosphates low or rich in silica in the same way, whereas in the known processes it was necessary either a mineral with a SiQg content of greater than 2.5 wt.% (British No. 902,361), or a mineral with an SiO2 content of less than 2% by weight (French Pat. No. 2,026,878).

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The claimed process is a thermal process, which in practice can only be carried out continuously and includes the following four steps: initial attack, conditioning, calcination, quenching.

T) The hegin attack of the mineral is effected by first adding phosphoric acid to the latter and then, after a reaction time of more than 5 minutes, a sodium-containing additive and recycled fine material; the latter reactants are fed in such an amount that in the final product the molar ratios CaO / NagO / PgO2 are between 7.6 / 1 / 2.9 and 3.6 / 1 / 1.5.

The mineral used must have a grain size such that the reaction of the phosphoric acid proceeds sufficiently quickly. Generally, a mineral with an average particle size of 150 microns is used. The attack can be carried out in any suitable mixer, such as conventional series-mounted attack vessels for phosphoric acid and mixers with horizontal arms. The phosphoric acid is preferably an acid, obtained by the wet road with a strength of 25 - 55% 20 PpOj., Which acid can be added cold or at 50 - 60 ° C if it is prepared in a neighboring place, so that the duration of attack is can be shortened.

The sodium-containing additives are added after a time of at least 5 minutes of attack of the phosphoric acid, varying depending on the mineral and the equipment used. Preferably sodium carbonate or sodium hydroxide are used, but it is possible to use any other sodium salt, such as the sulfate, nitrate, chloride or phosphate; mixing is continued until a satisfactory hamogenization of the treated masee is obtained.

The conditioning is effected at a drying temperature above -100 ° C by the calcination gases in the form of granules with dimensions between <2.5 and 5 mm. The conditioning device differs depending on whether a solid 8000-220k sodium-containing additive is used, such as sodium carbonate or a liquid, such as a solution of sodium hydroxide.

If a solid sodium containing additive is used, the mixture homogenized according to 1) is introduced into a lump breaker, followed by a sieve, which separates the large-sized particles recycled to the entrance of the lump breaker, which are sent to a dryer are guided. Any drying agents which do not cause destruction of the granules are useful, in particular a rotary oven 10. or tunnel heating heated by the gases from the calcination, bringing the temperature of the product above 100 ° C. The dried product is screened to separate the fractions smaller than 0.5 mm which are recycled to the feed point of the sodium containing additive during the initial attack of the mineral while the particles larger than 5 mm are recycled to the lump breaker, while the product with dimensions between 0.5 and 5 mm is fed to the calcination preheater.

When the sodium-containing additive is liquid, the slurry from the front attack is fed directly into a dryer granulator. The granules formed, which are brought to a temperature of at least 100 ° C, are sieved, the fine material is recycled to the entrance of the granulator, the coarse material is recycled to the pre-attack, while the particles with dimensions between 0.5 and 5 mm. to the calcination preheater.

3) The calcination, which must be performed at a temperature between 1100 and 130 ° C and preferably between 1180 and 1250 ° C, is preceded by a preheating step, in which the introduced particles are brought to a temperature of about 400 ° C. gases leaving the calcinator. The calcination can be done in a fluidized bed or in a rotary oven.

If a fluidized bed is used, 8000220 5 preheating and calcination are carried out at 1150 - 1250 ° C in two separate devices while in the case of using a rotary oven, a single device is used for preheating, which is carried out in the coldest part 5 of the rotary oven. The gases leaving the preheater are used to condition phase 2 and the combustion air is preheated in the subsequent quenching by cooling the calcined product.

It is generally preferred to carry out the calcination, as is known, in the presence of steam. If the calcination is carried out using a fuel burner, 10-20 vol. Of steam is added to the resulting gaseous mixture. If the calcination is carried out with a gas burner, the vapor produced by combustion of the gas is sufficient.

U) Quenching should allow the calcined product to cool as quickly as possible and in any case in less than 2 minutes. Preferably quenching with cold air is carried out under conditions such that the temperature of the product leaving the calcinator is brought from at least 800 ° C to at least 800 ° C in less than 2 minutes. The techniques of the fluidized or vibrating bed are particularly suitable for working such a quench. A cooler with cold air e.g. with tape or fluidized bed, brings the resulting defluorinated phosphate to ambient temperature, the calories recovered at this stage e.g. can be used to feed a boiling kettle or to be used for drying stage 2.

The defluorinated phosphates prepared by this method, which have the sum of the above-mentioned properties, make it possible to meet different requirements of the users, the respective contents of the different crystalline phases being particularly essential to obtain products which are completely animal feed 8000220 6 days.

Many devices are suitable for obtaining the defluorinated phosphate according to the invention. The drawing depicts a schematic in a satisfactory embodiment. The mineral and the phosphoric acid are introduced through the lines 1 and 1, respectively. 2 in the first part 1 of a horizontal double worm mixer I / IX; in the second part II of this mixer, at 3 the necessary sodium-containing additive is added and at U the fines originating from the sieves VI or 13 are recycled. In the case of a solid sodium-containing additive, the resulting mixture is gelated in the lump breaker III, followed by a sieve U through channels 5 and 6, then to a dryer V and a sieve VI through 8 and 9, while the fine material of VI is recycled to 2 by U and the coarse material at III via 22 and 7 · In the case of a liquid sodium-containing additive, the resulting mixture is passed via 23 into the dryer granulator XII and then to the sieve about 2h XIII, the coarse and fine material of which is recirculated to II via 26 and U. The granules leaving at VI or XIII feed the preheating of the calcmermg via 10 and 25- The preheater VII is followed by a calcinator VIII, which via 12 it is fed with warm air and with a fuel via 13 and possibly via 1 ^ with steam. The calcined product enters quenching device IX through 11, where it is cooled with cold air supplied via 15, then introduced into a cooling device X using cold air via 16 at 18 and leaving via 27. The resulting fluorinated phosphate leaves the device cold via 17.

To further improve the recovery of ... ...

the calories feeds the air coming from the preheater at 19 e.g. the dryer V, as shown (or the granulator dryer XII), while the cooled gases are evacuated via 20 to a washer and purifier XI, before being vented into the atmosphere via 21.

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Example I

Mixer I is fed via 1 with 100 wt. parts / hour of a Togo phosphate with an average diameter of 150 and a content of 36.5%, 15% F and 51% CaO. Via 2, 5 parts / hour of H 2 PO 3 with 35 # PgO 2 are added and then via 3 parts / hour of sodium carbonate. The mixture leaving at 5 is decortified in III, sieved at IV to a particle size less than 5 mm, dried in V at 120 ° C and sieved again in VI to eliminate the fine and coarse material formed on drying. The resulting granulated product is preheated, then calcined in a rotary oven VTI / VIII for 2 hours, where it pours from a temperature of 120 ° C to 12 ° C, while the flue gases start out at 550 ° C. The starting product is quenched at 600 ° C in a fluidized bed LX and then cooled to ambient temperature at X.

Taking into account the recirculations indicated above, 127 parts / hour of a defluorinated phosphate with the following characteristics are obtained: P total 18.1 + 5 # 20 F, 0.02 #

Ca 29.5 #

After 7.8 #

Spindle 8 ppm

Crystalline phase Na ^ Ca ^ PÖ ^) ^ 95 # 25 Crystalline phase apatite not detected

Crystalline phase Ca ^ iPO ^ Jgö not detected

Solubility in citric acid 96 #

Example II

Mixer I is fed with 100 parts of the same Togo phosphate as in Example 1, 1 + 5.5 parts H 2 PQ 2 with 35 # PgO 2 and 20 parts Na 2 CO 2. The treatment is carried out exactly in the same manner as in Example 1 and 122 parts of a defluorinated phosphate which is suitable for animal feed and which has the following properties are obtained: 8000220 δ Ρ total 18.0% F 0.181

Ca 29.8%

Ha 6.2% 5 As 8 ppm

Crystalline phase Ha2 Cag (PO ^) ^ 90%

Crystalline phase apatite not detected

Crystalline phase Ca ^ (PO ^ Jg & 2%

Solubility in citric acid 92%

Example III

This example is performed with the same Togo phosphate and under the same conditions as in Example I except for preheating and calcination; the preheating is effected in a cyclone at 120 ° C to 700 ° C, immediately followed by a calcination in a fluidized bed at 1220 ° C. The resulting fluorinated phosphate has substantially the same properties as the product obtained in Example I.

Example IV

Under the conditions of Example I, 100 parts / hour of a Moroccan phosphate mineral was treated with 32.3% PgO2, k% F and 51.9% CaO with 63.5 parts / hour. 35% PgO 2 and 25 parts / hour HagCO 2 129 parts / hour of a phosphate having the following properties are obtained: P. total 18.3% 25 F 0.06%

Approx 29.5%

Ha 6.9%

As- 6 ppm

Crystalline phase Ha ^ Cag (PQ ^) j. 9 ^% 30 Crystalline phase apatite not detected

Crystalline phase Ca ^ (? 0 ^) 2 ^ '3%

Solubility in citric acid 9 ^%

Example V

This example is performed with the same 8000220 9

Moroccan phosphate and under the same conditions as in Example 17 except for preheating and calcination, where instead of a rotary oven, preheating is performed in a cyclone from 120 ° C to T00 ° C, immediately followed by a calcination at 1220 ° C.

The resulting fluorinated phosphate has the following properties: P total 18.5 $ F 0.12 $ 10 Ca 29.5 $

Ha 6.9 $

Shaft 6 ppm

Crystalline phase Ha ^ Cag (PO ^) ^ 90 $

Crystalline phase apatite not detected. Crystalline phase Ca ^ 0 ^ $

Solubility in Citric Acid 90 $

Example 71

This example is performed with the same Moroccan phosphate and under the same conditions as in Example 17, however, using 82.3 parts per hour of H 2 PO 3 with 27% PgO 4 and 38 parts per hour of a 50% sodium hydroxide solution in water.

129 parts of a defluorinated phosphate having the same properties as that of Example IV are obtained. Example VII

25 This example is performed with the same

Moroccan phosphate and under the same conditions as in Example IV, but 57 parts of H 2 PO 3 with 35% PgO 2 and 22 parts of HaCl are used. 123 parts of a defluorinated phosphate are obtained, which have the following properties: 30 P 18.3% F 0.08%

Approx 29.5 $

Ha 6fkfS

Spindle 6 ppm 8000 220 10

Crystalline phase Ka ^ Ca ^ (PO ^) ^ 91 $

Crystalline phase apatite not detected.

Crystalline phase tricalcium phosphate 3 $ Solubility in citric acid 92 $

Example VIII

This example was performed with the same Moroccan phosphate and under the same conditions as in Example VII, but using 25 parts anhydrous KagSO2 instead of KaCl. 123 parts of a defluorinated phosphate containing the following properties are obtained: P 18.3 $ F 0.09 $

Approx 29.5 $

Ka β, Α $; 15 As 6 ppm

Crystalline phase Ka ^ Cag (PO ^) ^ 90 $ - Crystalline phase apatite not shown

Crystalline phase tricalcium phosphate k% 20 Solubility in citric acid 91.6 $.

8000220

Claims (5)

1. Calcium phosphate, characterized by the following properties: P total 15-21% by weight F <0.2% 5 Ca> 25 # Na 6 - 1055 As 10 ppm Crystalline phase Na ^ Ca ^ PO ^) ^. ^> 10% Crystalline phase apatite <£ \% 10 Crystalline phase Ca ^ PO ^ 8 <£ 5% Solubility in citric acid 90% Phosphate according to claim 1, characterized in that the phosphorus content is between 18 and 19 #. 3. Phosphate according to claims 1-2, characterized in that the solubility in citric acid is greater than 9b%. h. Process for preparing calcium phosphate by heat treatment according to any one of claims 1 to 3, starting from natural phosphates, comprising a pre-attack of the mineral with phosphoric acid and a sodium derivative, a conditioning to granules of the product thus obtained with recirculation of the fine material, a defluorination by calcination with the addition of steam and a quenching treatment, characterized in that the attack is carried out by first adding to the mineral phosphoric acid and then after a reaction time longer than 5 minutes, the sodium-containing additive, after which the fines are recycled, while the reactants are introduced in an amount such that the final product has the molar ratios of CaO / Na 2 O / PgO 2 between 7.6 / 1 / 2.9 and 3, 6/1 / 1.5; h.2) Conditioning is carried out with a 8000220 drying temperature above 100 ° C, through the flue gases from calcination in the form of granules with dimensions between 0.5 and 5 mm; h.3) Calcination defluorination is carried out at a temperature between 1100 and 1300 ° C using air preheated at the quench temperature as the combustion sustaining agent; h.h) The quenching of the calcined product is performed with air at a temperature below 800 ° C in less than 2 minutes. 5. Process according to claim k, characterized in that sodium carbonate is used in the pre-attack as sodium-containing reactant. 6. Process according to claim h, characterized in that in the pre-attack, sodium hydroxide is used as the sodium-containing reaction component. 7. Process according to claim h, characterized in that the calcination, which is carried out in a fluidized bed at a temperature of 1150 - 1250 ° C, is preceded by preheating flue gases leaving the calcinator at 700 - 800 ° C. 8. Process according to claim 7, characterized in that the preheating is effected by direct exchange of the calories between the flue gases originating from the calcinator and the supplied product. Process according to claim b, characterized in that the calcination is carried out in a rotary oven, the maximum temperature of which is between 1150 and 1250 ° C. 10. Use of the phosphate according to claims 30 1-3 as a complement for animal feed or as a component of a complement for animal feed. 8000220 r -, ---------- τ- - - a 2 3 4 'I v «v / Y λ *] ___] __ I I JL! ΓΤ _._ »_--------------------, I« i Ί 23i “! 5. A r t! ! t ./ί 311 'j! ί _ ^ _ J! xe i! 21 «1 e 7 y; I - "5-!!! Y ^ \ m vl L_I f 20 8 22 + r ~ P 'it v - X _ I -A ^ · 13 ïsf \ [—ί A 25 ___I f ~ r« W "7ΠΓ - γ A 11 12 27j no. -JL> - x -¾ ^. 8 0 0 0 2 2 0 "* 3 ^