IL29989A - Manufacture of ammonium phosphates and nitrate from natural phosphates - Google Patents

Description

The purpose of the nvention is the manufacture of ammonium phosphates and nitrate from solutions obtained as result of nitric acid attack on natural degree of purity of the diammonium phosphates obtained is such that they can be used eithe for the preparation of or the production of liquid or solid or the manufacture of gents such as alkali The ammonium nitrate obtained b the conversion of calcium is directly usable itself for example the liquid or solid fertilizer the carbonate containing all the ties of the attack liquor small amounts ammonium nitrate is advantageously if for improvement of soils in a The process of invention notable technical V making it possible to attain a rate of with recovery of phosphoric ion of at least a greatly reduced water In the same the ammonium nitrate recovered represents practically other the conversion of the residual calcium nitrate to ammonium nitrate is effected under particular conditions that make it to increase considerably the rate of transformation and substantially to imprpve filterability of the calcium In process essentiall extraction of the phosphoric and nitric acids contained in the starting solution with polar organic the concentration of calcium nitrate in the solution having been previously reduced by fractional if purification of the the nitric and phosphoric acids separated by ammoniacal the residual calcium nitrate being converted to ammonium nitrate by double decomposition with carbon dioxide and The continuous or batoh operation of the various processes together with judicious recycling of the several effluents with respect to the results that can be a ver important technical improvement compared with known processes usually solution from the nitric attack o natural phosphates if successive coolings between which the crystals tetrahydrated calcium nitrate are separated by This of which it is possible to remove more than by weight without harming the economy of the is recycled to the final conversion to ammonium after havin been washed the nitric acid used for the attack on the phosphated mineral starting The nitric and phosphoric acid contains in solution all or part of the calcium nitrate as well as al the soluble impurities present in the such and It is subjected to a traction in the of a polar alcoholic preferably chosen among the branched or linear aliphatic alcohols containing 4 to carbon atoms in the for come from a Oxo The extract containing the and of the nitric and phosphoric is purified by counter current treatment with recycled aqueous solution from the tration and washing of the ammonium phosphate produced at the end of the and having email quantities of ammonium phosphate which remained in and of This solution entrains the calcium nitrate as well as the impurities present in the crude extract and recycled to solvent extraction The puri extrac neutralized by ammonia and the light phase containing the solvent and a small amount of separated by decantatlon from the heavy phase by a slurry of ammonium phosphate crystals in an aqueous solution saturated with ammonium The choice of the neutralizatio pH makes it possible to direct the reaction toward the formation of mono dlammonium The heavy phase filtered and the crystals and dried All or part of the aqueous iltratio solution and all o the wash wate are used i the purification of the crud will be The light phase recycled to the solvent raffinate from the solvent extraction contains some calcium nitrate and ammonium all of the impurities the starting as a small quantity of It added to the eventual residue of the filtrate separated from the phosphate before being to distillatio to recover vapors at the that are recycled to the extraction after The distillation possibly mixed the calcium nitrate tetrahydrate fractional crystallization from the solutio resulting from the nitric attack on the are mixed with carbon dioxide and gaseous The presence of nitrate in the solution favors the increase of the speed of reaction of double decomposition which occurs at about and makes it possible to obtain a calcium carbonate precipitate eas to and latter contains small amounts of ammonium nitrate and all of the impurities present in the initial attack The concentrated solution of ammonium nitrate thus obtained can be as for certain formulations of liquid or concentrated and granulated to obtain pure The calcium carbonate precipitate is advantageously for the imrovment of soils deficient in attached to this concerns the manuf cture of moniaammonium phosphate and ammonium Given exclusively as tive of the it well that the latter will not be limited the manufacture of only this salt of phosphoric acid nor to the operating conditions which are described in Into the attack zone 3 are admitted simultaneously and continuousl at of phosphated mineral originating in Morocco and titratin of and at nitric acid titrating a mixture of phosphoric and nitric resulting from the attack are introduced into the draining and cooling zone at Thus crystals of calcium nitrate tetrahydrate are obtained after washing in 5 with nitric introduced at 6 and sent through 2 to the mineral represent of containing of The whose hourly represents t of t of and of are at into a extraction battery contacted wit o solvent constituted by a mixture of and of Oxo alcohols currently at She crude extrac leaving the extraction battery at at a feed of 53 contains the solvent and all of the nitric and phosphoric It is introduced into a second tion battery 11 vhich it is purified currently by a solution recycled at 25 from a later stage of the manu acture and having a high ammonium nitrate extrac leaving the extraction battery 11 a 12 is admitted into the neutralization and decantatlon zone 13 which it undergoes reaction with of gaseous ammonia introduced at A device not represented on the regulates the ammonia feed so as to maintain the at a essentially equal to in the Thus at 15 there is received of a light phase containing the major t organic phase is recycled to the solvent of the extraction battery 8 after addition at 16 of a balance of t h of nitric and at 17 of the fraction of solvent recovered in the A slurry of crystals is withdrawn ultaneously and eontinuously at the base of the zone 13 and is into 18 a drainage zone where the crystals are separated from the liquors then washed by of wate duced at Thus at 20 are of moist monobasic ammonium phosphate which after drying yield pure d representin recovery with respec to the quantity of in the ing From the separation and washing 18 simultaneously of washing crystals containing of recovered at 21 and of neutralization liquors containing and withdrawn a A fraction 23 of the representing a of t h is added 24 to the washing waters coming from 21 and introduced at 25 into the tion zone 11 where they serve in the purification of crude She aqueous phase leaving the cation 11 at and carrying with all of the of the crude extract cycled at 27 to the solvent extraction battery The leaving the battery at whose feed is contains of as well as all the impurities of the crude It is added at 29 to the second fraction 30 comin from and together feeds distillatio column At the head of the column t h of alcohol is recovered recycled afte condensation to the solvent circuit battery 8 passing through 17 and The raffinate freed of the alcohol solvent that is received at a distillation tails of the raffinate is added at 33 to the calcium nitrate tetrahydrate crystals previously washed with nitric acid The resulting mixture introduced into the nitrate conversion zone 34 in which are simultaneously of at 35 and of carbon dioxide at After the ammonium nitrate solution containing precipitated calcium carbonate introduce through 37 into the where the precipitate is washed by T h of water entering through At 40 the following is obtainedi of moist calcium carbonate equivalent to t of anhydrous retaining t of ammonium nitrate and all of the impurities present in the starting phosphonitric This produc can be used to Improve soils poor in Simultaneously of an solution containing t of are drawn at This ammonium nitrate solution concentrated to is stored as is or sent on to be concentrated and granulated the form of pure in devices no insufficientOCRQuality

Claims (2)

WHAT IS CLAIMED IS:

1. Process for the production of mono and/or diammonium phosphate in vhich phosphate ore is attacked by nitric acid, part of the calcium nitrate formed is optionally separated by crystallisation from the reaction mixture, the reaction mixture is treated i an extraction step with an organic solvent to obtain an aqueous solution containing traces of solvent, impurities and calcium nitrate and an organic extract containing phosphoric and nitric acids, the organic extract is purified in an purification extract is ammoniated to obtain diammonium phosphate ,according containing the solvent and an heavy aqueous phase containing ammonium nitrate and ammonium phosphate, the light phase is separated by decantation and recycled to the extraction stop and ammonium phosphate is separated from the heavy aqueous phase and washed, characterized in that the washing waters of ammonium phosphate and part of the heavy %quoous phase containing ammonium nitrate and ammonium phoephate are recycled to the puri ication step and that the aqueous solution from the purification step is introduced into the extraction step. Claim 1

2. A process according to characterized by the fact that calcium nitrate contained in the aqueous phase issuing from the extraction step, and which is mixed with introduced significant amount of ammonium nitrate brought- by the P.A. 29989/11 recycled washing waters and heavy aqueous phase is subjected to conversion to ammonium nitrate and calcium carbonate by the action of carbon dioxide and ammonia* 3» A process according to Claim 2, characterized by the fact that calcium nitrate contained in the aqueous phase from the extraction step is mixed with calcium nitrate separated by crystallization from the nitric acid attack mixture before the extraction step, ¾. A process aocording to Claim 1, wherein the solvents are chosen from branched or straight chain aliphatic alcohols containing k to 6 carbon atoms, 5, A process according* to Claim wherein the alcohols are Cj.-alcohols obtained by oxo-sy thesis, 6, A process according to any of Claims 1 to 5 wherein the heavy phase resulting from ammoniation is a slurry o ammonium phosphate in an aqueous solution saturated with ammonium nitrate, and during the treatment with ammonia the pH is maintained equal to or substantially equal to 3· 5 7· A process for the production of ammonium phosphates and ammonium nitrate substantially as herein described with reference to the Example and the drawing. 8· Ammonium phosphates and nitrate whenever produced by the process of any of Claims 1 to 7· ATTORNEYS FOR APPLICANTS