FR2564817A1 - PROCESS FOR THE PRODUCTION OF CALCIUM HYDROGEN PHOSPHATE AND / OR ANHYDROUS FORM - Google Patents

Abstract

A.PROCESS FOR THE MANUFACTURE OF HYDROGEN PHOSPHATE OF CALCIUM DIHYDRATE OR IN ITS ANHYDROUS FORM. B. CHARACTERIZED IN THAT THREE-HYDROGEN PHOSPHORIC ACID, A WATER-SOLUBLE CALCIUM SALT, AND AMMONIA, OR AMMONIUM HYDROXIDE, OR A MIXTURE OF THESE ARE REACTED MATERIALS WITH MAGNESIUM OXIDE OR HYDROXIDE, AMMONIUM, OR AMMONIUM HYDROXIDE, AND REGENERATES THE CALCIUM SALT SOLUTION, FOLLOWING WHAT IS RECYCLED IN THE MANUFACTURING OPERATION PART OR ALL OF THE WATER SOLUBLE CALCIUM SALT SOLUTION, OR PART OR ALL OF THE AMMONIA, OR PART OR ALL OF THE AMMONIUM HYDROXIDE. C. THE INVENTION RELATES TO A PROCESS FOR THE MANUFACTURE OF HYDROGEN PHOSPHATE OF CALCIUM DIHYDRATE OR IN ITS ANHYDROUS FORM.

Description

25648 1 7

  Process for the production of calcium hydrogen phosphate dihydrate and / or its anhydrous form I. The invention relates to a process for the production of hydrogenated phosphate dihydrate dihydrate, and / or its anhydrous form, and / or mixtures thereof, or / and mixed with hydroxylated apatite, or / and with

  calcium phosphate, and / or with calcium carbonate.

  The processes using a precipitate

  represent, because of their simplicity, the procedures

  most common for the manufacture of

  above. Most often, we start with water-soluble calcium salts which must be discarded, and which are purified as necessary, or these salts are made by decomposing limestone with the acids. In the majority of cases, high demands are laid on the purity of the starting calcium-containing raw material. It is formed during the precipitation, as a secondary product, a

  ammonium salt or an alkali metal salt.

  As can be seen here, the inconvenience

  the manufacturing processes that have been used so far, lies first and foremost in the quality of

  of the product depends on the purity of the raw material con-

  holding calcium, and in that a waste product is formed which is difficult to valorize, in the form of a diluted solution. These disadvantages are eliminated by the process according to the invention for manufacturing hydrogenated phosphate-calcium dihydrate, and / or its anhydrous form, and / or mixtures thereof, and / or mixed with hydroxylated apatite, or and with calcium phosphate, and / or with calcium carbonate, characterized in that trihydrogenated phosphorine acid, a water-soluble calcium salt, and ammonia are reacted, or /and

  ammonium hydroxide, separates the precipitate from the

  pension that is formed that is processed to obtain the product, recovers, from part or all

  of the remaining solution, with oxide and / or

  calcium oxide or their mixture, or a mixture of these substances with magnesium oxide or hydroxide,

  ammonium and / or ammonium hydroxide and

  the calcium salt solution is formed, after which part or all of the water-soluble calcium salt solution, or / and some or all of the ammonia,

  or / and some or all of the ammonium hydroxide.

  According to another characteristic of the invention, a solution containing mainly calcium chloride, which is formed during the regeneration of ammonia from the liquors produced in the course of the regeneration of ammonia, is used as water-soluble calcium salt. the manufacture of sodium carbonate by the ammonia process. According to another characteristic of the invention, instead of directly using the solution

  of calcium chloride which forms during the regeneration of

  Ammonia from the washing liquors

  of sodium carbonate, they are used after

  and decrease the calcium chloride content.

  According to another characteristic of

  the invention according to the two methods above,

  father from some or all of the solu-

  containing mainly ammonium chloride, which remains after removal of the precipitate from the product, ammonia and / or ammonium hydroxide from the manufacture of sodium carbonate. According to another characteristic of

  the invention is used instead of a calcium salt

  water with ammonia and / or ammonium hydroxide, an ammoniacal solution of a calcium salt that forms during the regeneration of ammonia, from a salt solution of ammonia because calcium oxide and / or calcium hydroxide, or mixture thereof, is reacted with an ammonium salt solution, separates

  the remaining solid phase, and eventually makes ammonia

hold the solution that has formed.

  According to another characteristic of the invention, some or all of the trihydrogenated phosphoric acid and some or all of the ammonia and / or part or all of the ammonium hydroxide are replaced directly or after purification with dihydrogenated ammonium phosphate and / or

hydrogenated ammonium phosphate.

  According to another characteristic of the invention, the trihydrophosphoric acid is diluted with

  the water that must be rejected during the washing of the

  or with a solution containing an ammonium salt.

  According to another characteristic of the invention, inhibiting stabilizing agents are added.

  dehydration of the dihydrate or / and hydrolysis of the phos-

hydrogenated phate of calcium.

  The effect which is the basis of the invention

  tion is based on the fact that it is not necessary to start with very pure

  no unwanted salt is formed as a by-product.

  When the manufacture of hydrogenated calcium phosphate is combined with the manufacture of sodium carbonate, part of the production plant may be common

  for the manufacture of both products, which is

  in terms of investment and manufacturing costs. As a result, the manufacturing method according to the invention is substantially more advantageous, if one compares it with the methods known hitherto, to the point of

economic view.

  For manufacturing, one can proceed continuously, discontinuously, or combining these two ways of proceeding. For example, the following procedure is carried out: a solution of trihydrogenated phosphoric acid with a concentration of 1 to 95% by weight is mixed in one or more steps, a solution of

  of a water-soluble calcium salt with a concentration of

  which can range from 1% by weight to saturation

  at the given temperature, and ammonia and / or hy-

  ammonium hydroxide, at the same time or successively;

  optionally, it is also possible to dilute the mixture.

  Depending on the desired product composition, the temperature can range from 0.degree. C. to the boiling point. The precipitate, which is formed, is separated, for example by filtration or centrifugation, washed and dried, possibly partially or completely dehydrated by a heat treatment, in order to obtain a product.

  of the desired composition. From the solution

  ammonium salt, ammonia and a calcium salt soluble in water, with the aid of calcium oxide or calcium hydroxide, or their mixture, are recovered at room temperature. solid state or in aqueous suspension, for example in the form of cooked lime and / or hydrated lime, and / or milk of lime. Ammonia and / or ammonium hydroxide and the solution of a water-soluble calcium salt may be recycled, after mechanical impurities have possibly been removed.

  partially or totally in the manufacturing operation

  tion, possibly after being concentrated and re-

  froidis. The wash water can be incorporated into the

  production cycle. Additives, which delay the

  hydration and / or hydrolysis of hydrogen phosphate anhydrous calcium dihydrate, for example diphosphate

  sodium, may be introduced in a

  mined, preferably in the solutions sent to the pre-

  citation or / and directly in the installation of preci-

  pity, or / and in the wet or dry product, and / or in

  possible treatment concerning the size of the particles

the, by grinding.

  The process according to the invention is described in more detail in the following, with reference

  to concrete examples of realization.

Example 1

  A 10% solution of calcium chloride is mixed, with stirring, with an equivalent amount of trihydrogenated phosphoric acid, the concentration of which is 85% by weight. The pH is adjusted to 7

  with ammonia gas. The temperature does not exceed 30 C.

  The precipitate which forms is separated by filtration, washed and dried. As the final product, hydrogenated phosphate dihydrate dihydrate is obtained. The filtrate and the washing water are sent together with calcium oxide, which is used in a proportion corresponding to an excess of stoichiometry of 0.5%, calcined on the

  ammonium chloride, in the regeneration plant.

  In the regenerator, the solution is maintained at

  boiling temperature. The suspension that leaves the

  The generator is freed from mechanical impurities by

  tion, and the clear filtrate is used after

  concentration and cooling, together with ammonia

  regenerated, again to precipitation.

Example 2

  The operation is carried out as in Example 1, however with the difference that instead of a 10% solution of calcium chloride, a solution is used which is formed as waste during regeneration.

  of ammonia from the detergents of a

  than sodium carbonate with lime milk, and which contains as main components chlorides of

  calcium, sodium and magnesium.

Example 3

  To a 10% by weight solution of ammonium chloride, hydrated lime is added in a proportion which corresponds to

  a 10% excess of stoichiometry. We stir the

  in a closed vessel at a temperature of C for 20 minutes, then cooled to 200 ° C, and filtered off to a solution and an undissolved solid phase. The clear solution of calcium chloride, ammoniacal, is mixed in a reactor operating batchwise, while stirring, with trihydrogen phosphoric acid whose concentration is% by weight, in the stoichiometric ratio, calculated on the hydrogenated phosphate formation of calcium. The

  The temperature of the reaction is kept at 30 C.

  The precipitate which forms is filtered off, washed and mixed with a solution of sodium diphosphate which contains 1% by weight of this salt calculated on the weight of

dry product, and dried at 40 0C.

  As a phosphate product

hydrogenated calcium dihydrate.

Example 4

  The method of manufacture is the same as in Example 1 with the difference that the temperature in the reactor is maintained at 80 ° C., and that the precipitate is dehydrated by heating at a temperature of 7 ° C.

115 C temperature

  The product of phosphate is obtained

hydrogenated anhydrous calcium.

  The products obtained are suitable for use in the cosmetics, food, and pharmaceutical industries, and as an enrichment product for

  feed mixtures in livestock production.

Claims (7)

R E V E N D I C A T I 0 N S CLAIMS   1) Process for the production of calcium hydrogen phosphate dihydrate, and / or its anhydrous form, and / or mixtures thereof, and / or in admixture with hydroxylated apatite, and / or with calcium phosphate, or and with calcium carbonate, process   characterized in that phosphoric acid is reacted   A trihydrogenated salt, a water-soluble calcium salt, and ammonia, or / and ammonium hydroxide, separate the precipitate from the formed slurry which is treated to obtain the product. recovering, from part or all of the remaining solution, with calcium oxide and / or calcium hydroxide or mixture thereof, or a mixture of these materials with oxide or   magnesium hydroxide, ammonium hydroxide, and / or hydrogen   ammonium hydroxide, and regenerates the calcium salt solution,   following which we recycle in the manufacturing operation   part or all of the water-soluble calcium salt solution, and / or part or all   ammonia, and / or some or all of the hydro- ammonium hydroxide.   2) Process. according to claim 1, characterized in that a water-soluble solution is used as the water-soluble calcium salt.   calcium chloride, which forms during the regeneration of   ammonia from the detergents produced in   during the manufacture of sodium carbonate by the yielded to ammonia.   3) Process according to claim 2, characterized in that instead of directly using the calcium chloride solution that is formed during the regeneration of ammonia from the sodium carbonate production liquors, they are uses after concentration and decrease in chloride content of calcium.   4) Process according to any one   Claims 2 and 3, characterized in that one   recovering from part or all of the solution containing mainly ammonium chloride, which remains after removal of the precipitate from the products ammonia and / or ammonium hydroxide from the manufacture of sodium carbonate.    ) according to any one of   Claims 1 to 3, characterized in that instead of   a water-soluble calcium salt and ammonia and / or   of ammonium hydroxide, an ammonia solution   Calcium salt which is formed during the regeneration   ammonia, from a solution of salt   because of the reaction of calcium oxide with   and / or calcium hydroxide, or their mixture, and an ammonium salt solution, separates the remaining solid phase, and eventually makes the solution ammoniacal which has formed.   6) Process according to any one   Claims 1 to 5, characterized in that one   replaces some or all of the trihydrogenated phosphoric acid and some or all of the ammonia and / or some or all of the ammonium hydroxide,   directly or after purification with ammonium phosphate   dihydrogenated nium or / and hydrogenated ammonium phosphate.   7) Process according to any one   Claims 1 to 6, characterized in that one dilutes   trihydrogenated phosphoric acid with the water released during the washing of the product precipitate, and / or with a   solution containing an ammonium salt.   8) Process according to any one   Claims 1 to 7, characterized in that   stabilizers that inhibit dehydration and / or   lysis of hydrogenated calcium phosphate, dihydrate.