Abstract: This invention concerns the solubilization of phosphate values in phosphate bearing rock which contains high contents of aluminium and/or iron by attacking the phosphate rock with a nitric acid leach solution for a time suitable to produce a phosphate rich leach solution containing no more than 10 parts Fe and Al in solution calculated as R.sub.2 O.sub.3 per 100 parts of P.sub.2 O.sub.5 in solution.

Abstract: A process is described for producing high purity phosphoric acid from phosphate rock including low grade phosphate rock material such as Idaho phosphate ores having P.sub.2 O.sub.5 contents as low as 20 percent. Finely divided phosphate rock, sulfuric acid, phosphoric acid and water are charged to a mixing zone in proportions such that the pH of the resultant slurry is in the range 0.8 to 1.2 and the calcium ion content of the liquid phase of the slurry is in the range 3 to 4 percent by weight. Sulfuric acid is charged to the mixing zone in a quantity sufficient to convert the nonphosphate calcium compounds in the rock to calcium sulfate plus the quantity required to convert the contained calcium phosphate to monocalcium phosphate, phosphoric acidis charged to the mixing zone in quantities such that it is, on a molar basis, from about 1.2 to about 1.4 times the P.sub.2 O.sub.

Abstract: There are disclosed methods for removing fluorine values from fluorine-containing waste waters, in which aluminum ions are added to fluorine-containing waste water to convert fluorine to hydroxyfluoride complexes, adding phosphoric acid or phosphate and calcium compound are added to form fluoride apatite with residual fluorine in the waste water, and the hydroxy-fluoride complex and fluoride apatite are removed from the waste water.

Abstract: A process is provided for the defluorination of wet process phosphoric acid whereby hydrogen ion is removed, and the concentration of P.sub.2 O.sub.5 is adjusted with water, the calcium concentration, calculated as CaO, is adjusted by adding a source of calcium phosphate at temperatures of about 25.degree. C. to 75.degree. C. while maintaining a pH of about 2 or below to achieve substantially the maximum calcium content in aqueous solution and raising the temperature of the solution to about the boiling point to initiate the hydrolysis of silicofluoride and precipitate calcium fluoride which is separated, thereby producing a solution with an enhanced phosphoric acid content.

Abstract: Phosphate rock is calcined under conditions calculated to completely oxidize the carbon and sulfur in the rock. Calcination is also conducted at elevated temperature to eliminate cadmium metal, a poisonous substance in fertilizers, from the calcined rock product. A fluid bed system for eliminating cadmium metal in the calcination of phosphate rock involves a two-vessel system in which an independent cadmium removal vessel served by a separate fluidizing air stream carries out volatilization of cadmium, while preheating, precalcining and cooling is conducted in another multi-bed reactor which is served by a separate fluidizing air stream.

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: Nitrous oxide losses are reduced by bringing acid to weakly alkaline salt solutions or suspensions into media containing nitrous oxide or media which develop nitrous oxide.

Abstract: In the process according to the invention, raw phosphate rock is decomposed with an aqueous solution of sulfuric acid and ammonium sulfate recycled from the conversion step of phosphogypsum into chalk, and then the decomposition liquor stream is divided into a partial acid plant stream (Liquor I) to be converted into phosphoric acid and a partial fertilizer plant stream (Liquor II) to be processed to a multi-component mineral fertilizer. From the acid plant stream (Liquor I) constituting up to 30 per cent by weight of the total decomposition stream, ammonium sulfate is precipitated and introduced into the fertilizer plant stream (Liquor II), all the above mentioned processes of decomposition, separation and precipitation being carried out continuously.

Abstract: Multinutrient synthetic fertilizers, containing potassium and phosphorus and, if desired, other elements of fertilizing value, are produced from phosphate rock or ore and potassium chloride in a method, in which calcium and chlorine are simultaneously removed as a solution of calcium chloride, said method comprising treating a solution of the phosphate rock or ore in a mineral acid with a cation exchanger charged with potassium ions in order to exchange at least part of the calcium ions of the phosphate rock solution with potassium ions, after which the ion exchanger and the solution are separated, the solution being worked up to the final fertilizer, and the ion exchanger being regenerated for renewed use.

Abstract: The invention relates to a combined process for the manufacture of feed grade dicalcium phosphate and pure phosphoric acid. The process comprises the reaction of an excess of phosphate rock with aqueous solutions of a mineral acid selected from hydrochloric acid, phosphoric acid and nitric acid, characterized by the fact that the free acidity of the dissolution liquor does not exceed 60% and that in the clear solution feed grade dicalcium phosphate is precipitated with calcium hydroxide, calcium carbonate or mixtures thereof. The solids comprising the unattacked phosphate are decomposed with hydrochloric acid solutions, gases containing hydrogen chloride or mixtures thereof and the acidulate containing the phosphoric acid is extracted with an organic solvent selected from butanols, pentanols or mixtures thereof, the phosphoric acid-solvent extract is separated and washed, thus obtaining the pure phosphoric acid.

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: A method of producing phosphorus-containing fertilizers, wherein the phosphate raw stock is treated with a mineral acid selected from the group, consisting of phosphoric acid, sulphuric acid and a mixture of both. The thus-obtained suspension of the phosphorus-containing fertilizers is acted upon by acoustic vibrations at a frequency of from 500 to 20,000 Hz and a second energy density of from 0.5 to 5 W/cm.sup.2, whereupon the end product is isolated.

Abstract: A method and apparatus for manufacture of wet process phosphoric acid wherein phosphate rock and sulfuric acid are separately added to a combination reactor and cooler unit at a rate of addition such that the increase in calcium content and sulfate content in the slurry contained in the unit are small. Circulation of the slurry is provided and the rate at which sulfuric acid and phosphate rock are added is small compared to the rate of circulation of the reactor slurry.

Abstract: A method for recovering substantially all of the fluorine and uranium values and at least 90 percent of the rare earth metal values from brine raffinate obtained as by-product in the production of phosphoric acid by the hydrochloric acid decomposition of tricalcium phosphate minerals. A basically reacting compound is added to the brine raffinate to effect a pH of at least about 9, whereby fluorine, uranium and rare earth metal values are simultaneously precipitated therefrom. These values may then be separately recovered from the precipitate by known processes.

Abstract: An improved process for preparing wet process phosphoric acid by calcining a phosphate source at a temperature in the range of 1600.degree. - 2200.degree.F. The phosphate source may be wet or dry mined phosphate matrix, phosphate slimes, phosphate pebble or other phosphate source.