Abstract: Process for the preparation of a purified solution of phosphoric acid, which may be partially neutralized, from wet process phosphoric acid, by liquid-liquid extraction by means of a substantially water-immiscible organic solvent. The phosphoric acid is treated in the selected solvent, preferably isobutyl alcohol, in the presence of sulphuric acid, by means of an aqueous solution containing phosphate ions and calcium ions in solution, the sulphate ions are precipitated in the form of calcium sulphate, and suspended in said aqueous solution which is separated from the phosphoric solution. The process is advantageously employed for the continuous preparation of concentrated solutions of monosodium phosphate.

Abstract: Phosphate values can be recovered from an organic extract which is formed by contact of wet process phosphoric acid and a water immiscible solvent, in a process in which the extract is treated with an inorganic base or a dihydrogen phosphate salt to give an acid free solvent and an aqueous solution of phosphoric acid and phosphate salt with a cation to P usually in the 0.1 - 0.5 : 1 region. The aqueous solution represents a concentrated soluble phosphate source for subsequent neutralization and conversion to e.g. tripolyphosphates.

Abstract: A method is disclosed for the manufacture of phosphoric acid directly from phosphate rock wherein the crushed phosphate rock is mixed with dilute phosphoric acid to form a slurry and the slurry is then heated to produce calcium monophosphate. Thereafter, oxalic acid is added to the slurry to precipitate the calcium therein as calcium oxalate which is separated. The liquid resulting therefrom which contains the phosphoric acid from the rock is then treated conventionally to recover the phosphoric acid therein.

Abstract: Substantially fluoride-free phosphoric acid is produced by the acidulation of phosphate rock with sulfuric acid wherein the acidulation reaction is conducted in the presence of added potassium as K.sub.2 O bearing compounds, e.g. KHSO.sub.4, K.sub.2 SO.sub.4, KH.sub.2 PO.sub.4 or KOH, and additional silica, to precipitate fluorides and silica as potassium silicofluoride and then removed on separation of the gypsum formed. Optionally, additional silica may be added to the phosphoric acid solution recovered after precipitation and removal of the gypsum, to precipitate additional fluoride as potassium silicofluoride to further purify the phosphoric acid. In a further embodiment sufficient potassium may be added along with additional silica in the acidulation step to produce potassium dihydrogen phosphate and phosphoric acid as additional products.

Abstract: Process for producing triple superphosphate by reacting dilute phosphoric acid and lime, limestone or dolomite and granulating the resultant product.

Abstract: Production of pure alkali metal phosphate solutions by neutralizing wet-processed phosphoric acid with an alkali liquor and/or carbonate. To this end, the wet-processed phosphoric acid is neutralized to a pH from 4 to 9, the resulting neutralization sludge consisting substantially of insoluble aluminum and iron phosphates is separated from the alkali metal phosphate solution and scrubbed with water, the sludge so treated is mixed with alkali liquor, alkali metal phosphate solution and water-glass so as to establish in the resulting suspension a molar ratio of SiO.sub.2 to Al.sub.2 O.sub.3 of at least 2 : 1 and a molar ratio of dissolved alkali metal oxide to dissolved P.sub.2 O.sub.5 ranging from 2.9 : 1 to 3.3 : 1, the whole is heated to temperatures from 80.degree. to 100.degree.

Abstract: A solid anhydrous crystalline compound of the formula H.sub.3 PO.sub.4 [(CH.sub.3).sub.2 CH].sub.2 O. The invention also provides a method of preparing phosphoric acid by evaporating diisopropyl ether off said anhydrous crystalline compound under reduced pressure.

Abstract: A method is disclosed for the acidulation of phosphate rock and the production of substantially pure alkali metal phosphates, calcium phosphates, and phosphoric acid which are essentially free of fluorides and recovery of the fluorine values from the starting phosphate rock in useful form. The steps of the method comprise initial acidulation of phosphate rock with a phosphoric acid solution containing sufficient alkali metal values to provide R.sub.2 O in the system, where R is alkali metal, to solubilize the phosphates and form an insoluble precipitate comprising a mixture of impurities, sand (SiO.sub.2) and the fluorides, from which the fluorides can be recovered in usable form. In preferred embodiments, after removal of the precipitate containing the fluorides, a portion of the solution of phosphoric acid and calcium phosphate is reacted with sulfuric acid and RHSO.sub.4 or R.sub.2 SO.sub.4 where R is alkali metal, to form a solution of RH.sub.2 PO.sub.

Abstract: Substantially fluoride-free phosphoric acid is produced by the acidulation of phosphate rock with sulfuric acid wherein the acidulation reaction is conducted in the presence of added potassium as K.sub.2 O bearing compounds, e.g. KHSO.sub.4, K.sub.2 SO.sub.4, KH.sub.2 PO.sub.4 or KOH, and additional silica, to precipitate fluorides and silica as potassium silicofluoride and then removed on separation of the gypsum formed. Optionally, additional silica may be added to the phosphoric acid solution recovered after precipitation and removal of the gypsum, to precipitate additional fluoride as potassium silicofluoride to further purify the phosphoric acid. In a further embodiment sufficient potassium may be added along with additional silica in the acidulation step to produce potassium dihydrogen phosphate and phosphoric acid as additional products.

Abstract: Alkali metal phosphate solutions of low vanadium content are produced from wet-processed phosphoric acids contaminated with vanadium and iron. The acids containing vanadium and iron in the highest stage of oxidation are treated with a reductant to effect conversion of the vanadium and iron contaminants to a lower stage of oxidation, the resulting acids are neutralized by means of an alkaline liquor and/or alkali metal carbonate down to a pH of at least 3, and the resulting precipitate is separated. The reductant used is the sodium salt of hydroxymethane-sulfinic acid.

Abstract: A method for removing fluoride ions from phosphoric acid by neutralizing said acid to a pH between about 5 and about 9, contacting the neutral salt solution thereby formed with an insoluble alkaline earth metal phosphate salt, and lowering the pH to convert the solution back to a purified acid.

Abstract: Precursors for the preparation of phosphate glasses are provided. Controlled preparation of the precursors in precise stoichiometric proportions enable the preparation of glasses which are stable and possess superior optical properties of an order similar to optical glasses. Suitable precursors within the contemplation of the invention are those having the formula:M(H.sub.2 PO.sub.4).sub.nwherein M is a metal ion selected from the group consisting of Al, Zn, Cd, Fe, Sn, Mn, Pb, Ni, Co, Ga, and In and the alkaline earth metals Be, Mg, Ca, Sr and Ba and wherein n has a value of 2 or 3 depending on whether M is a divalent or trivalent ion. Mixtures of these compounds may be employed, the admixture being made prior to melting stoichiometric equivalent precursor mixture. In addition, any combination of precursors containing divalent and/or trivalent cations may be selected.

Abstract: Phosphate values of high purity and concentration may be efficiently recovered from a wide range of phosphatic-mineral-containing materials including as-mined phosphate ore by leaching such ore with a dilute aqueous mixture of sulfuric and hydrochloric or nitric acid, and precipitating phosphate values as dicalcium phosphate. This product, which is already suitable for use in animal feed and agricultural fertilizer, can also be readily converted to the many other agricultural and industrial phosphate products without costly purification operations or means of control of pollution to the surrounding environment.

Abstract: The invention relates to a process for the manufacture of solid monammonium phosphate in a suitable form for use as an ingredient in the granulation of NPK compound fertilizers. It has been found that some wet-process phosphoric acids used in the manufacture of fertilizer grade ammonium phosphate contain impurities in amounts and/or ratios which can give rise to hard oversize product in known methods of manufacture with the result that extra milling of the product is required. The process of the invention overcomes the need for extra milling by providing an improved product form. The improvement is achieved by mixing separately at one stage in a process of the kind described between 15% and 85% by volume of the total secondary acid feed with the aqueous ammonium phosphate slurry and adding the remainder of the secondary acid to the treated slurry at a later stage.

Abstract: The present invention relates to an improved method for the manufacture of potassium phosphates. More specifically the present invention provides a process for the manufacture of monopotassium phosphate, KH.sub.2 PO.sub.4, from potassium bearing brines.

Abstract: Process for the production of granular mixed fertilizer in which ammonium phosphate melt is prepared in a pipe reactor and dispersed through a plurality of apertures in the wall of the pipe to bind small particles of fertilizer materials into granules. Wet-process phosphoric acid is ammoniated to an NH.sub.3 :H.sub.3 PO.sub.4 mole ratio of about 1.0 and the steam formed by the heat of reaction atomizes the ammonium phosphate melt resulting in proper distribution of the melt for granulation. Up to about 30 percent of the P.sub.2 O.sub.5 in the melt may be polyphosphate. The ammonium phosphate is essentially anhydrous and the granules of mixed fertilizers do not require drying. Elimination of drying greatly decreases investment, dust and fume evolution, and fuel requirement.

Abstract: In the manufacture of phosphoric acid by treatment of phosphate ores with excess phosphoric acid and precipitation of calcium ions as calcium sulfate, the purity and quality of the byproduct calcium sulfate is substantially improved by subjecting the monocalcium phosphate extract of the ore before precipitation of calcium sulfate to one or more preliminary treatments, whereby contaminent ions are substantially and preferentially removed from the extract while the calcium remains substantially in solution. These preliminary treatments may include separation of fluoride by reaction with silicon compounds, separation of radium by reaction with barium compounds in the presence of sulfate ions, and separation of strontium as strontium sulfate.

Abstract: There is disclosed a method and apparatus for the production of ammonium polyphosphate solutions of high concentrations from phosphoric acid and ammonia. The process is ideally suited for the production of such solutions from wet-process phosphoric acid which has a P.sub.2 O.sub.5 content of from 56 to about 70 weight percent, impurity-free basis, and which, preferably, contains from 5 to about 50 percent of its phosphorus present as polyphosphoric acid. The method comprises introducing the phosphoric acid into a reactor bearing a Teflon liner and reacting it therein with vapors of ammonia while controlling the amount of ammonia from 0.2 to about 0.3 pound ammonia per pound of P.sub.2 O.sub.5 in the feed acid, sufficient to achieve a peak reaction temperature in the reactor between about 525.degree. and 775.degree.F., the absolute value of which is dependent on the bulk water content of the feed acid.

Abstract: A solid anhydrous 1:1 molar compound of phosphoric acid and diisopropyl ether is prepared from a mixture of the ether and phosphoric acid in a molar ratio (R:1) of 0.6:1 to 1.4:1 at a temperature at least as low as the crystallization temperature (T.degree.C) governed by the relationship T = 25(1.2-R). Treatment of the compound with water or a base produces purified acid or a phosphate respectively.

Abstract: Fertilizer materials, especially potassium dihydrogen phosphate, are produced by the reaction of phosphate rock or a solubilized form thereof, such as mono calcium phosphate, dicalcium phosphate, etc., concentrated sulfuric acid, potassium hydrogen sulfate and, optionally fresh or recycle phosphoric acid, the resulting mixture is filtered to remove the calcium sulfate precipitate and the potassium dihydrogen phosphate is recovered from the filtrate, either by concentration and filtration or by extraction with an organic solvent.