Abstract: Embodiment No. 1. Urea phosphate prepared from wet-process phosphoric acid is heated with monopotassium orthophosphate in a mole ratio of 0.25 to 4.0 at 130.degree. to 200.degree. C. to form an ammonium potassium polyphosphate having an average chain length between 1.2 and 2.5. The ammonium potassium polyphosphate is dissolved in aqueous ammonia to yield concentrated fertilizer solutions containing the three major nutrients and over 50 percent total plant food.Embodiment No. 2. Phosphoric acid containing 54 to 76 percent P.sub.2 O.sub.5 is heated with urea (urea:H.sub.3 PO.sub.4 mole ratio 0.5 to 2.0) and monopotassium orthophosphate (urea:KH.sub.2 PO.sub.4 mole ratio 0.25 to 4.0) at 130.degree. to 200.degree. C. to form an ammonium potassium polyphosphate having an average chain length between 1.2 and 2.5. The ammonium potassium polyphosphate is dissolved in aqueous ammonia to yield concentrated fertilizer solutions containing the three major nutrients and over 50 percent total plant food.

Abstract: Purified diammonium phosphate is produced by neutralizing relatively pure melamine orthophosphate, prepared from wet-process phosphoric acid, with ammonia in a hot solution of diammonium phosphate to give a slurry of melamine in concentrated diammonium phosphate solution. The liberated melamine is virtually insoluble in concentrated diammonium phosphate solutions; it is filtered from the hot mixture, washed, and recycled to produce more melamine phosphate by reaction with wet-process phosphoric acid. The hot, concentrated diammonium phosphate filtrate is cooled to precipitate purified diammonium phosphate crystals. The product is separated from its mother liquor by filtration, and the resulting filtrate is recycled to the reactor. The small amount of impurities introduced with the melamine phosphate are removed partly with the liberated melamine and partly by centrifugation of the diammonium phosphate solution. The only starting materials for the process are phosphoric acid and ammonia.

Abstract: A method of selectively extracting calcite and dolomite away from apatite in phosphate rock or phosphatic limestone wherein the phosphate rock or phosphatic limestone is treated with a mixture of sulfur dioxide, water, and a carbonyl compound. Solids are separated from the liquid phase. The solids consist principally of apatite admixed with clay, quartz, and other accessory minerals originally in the rock. The solids are heated to drive off adhering sulfur dioxide, water, and carbonyl. The liquid phase consists of carbonyl, water, sulfur dioxide, and magnesium and calcium ions. Heating this liquid preferentially precipitates CaSO.sub.3.1/2H.sub.2 O. This solid is filtered off and the filtrate further heated to precipitate MgSO.sub.3.3H.sub.2 O largely free of CaSO.sub.3.1/2H.sub.2 O. All off gas and filtrate is returned to the process.

Abstract: A method of purifying filter-grade wet-process phosphoric acid, then converting the purified phosphoric acid directly to ammonium phosphate without first concentrating the phosphoric acid. The wet-process phosphoric acid is treated with a mixture of ammonia or an ammonium salt and acetone near or at the boiling point of the mixture. Solids are separated from the phosphoric acid liquid phase. The solids are a mixture of metal phosphates, gypsum, and fluosilicates. Adhering phosphoric acid is washed free of the solids with fresh acetone. Wash liquor is combined with purified phosphoric acid. Gaseous ammonia is added to the phosphoric acid-acetone extract in the ratio necessary to produce either monoammonium phosphate (MAP) or diammonium phosphate (DAP). Ammonium phosphate is filtered from the acetone-water mother liquor, then, depending on the level of ammonium phosphate left in the mother liquor and the type of ammonium phosphate produced (MAP or DAP), the mother liquor is treated in one of several ways.

Abstract: Crystalline urea phosphate is pyrolyzed in one stage to give molten urea ammonium polyphosphates that contains up to 95 percent of the phosphate as polyphosphate. These are then processed into high-analysis solid or liquid fertilizers. Addition of urea to the process to maintain a urea:biuret ratio of at least 16 prevents precipitation of biuret in the liquid fertilizers.

Abstract: A method of recovering uranium from wet-process phosphoric acid wherein the acid is treated with a mixture of an ammonium salt or ammonia, a reducing agent, and then a miscible solvent. Solids are separated from the phosphoric acid liquid phase. The solid consists of a mixture of metal phosphates and uranium. It is washed free of adhering phosphoric acid with fresh miscible solvent. The solid is dried and dissolved in acid whereupon uranium is recovered from the solution. Miscible solvent and water are distilled away from the phosphoric acid. The distillate is rectified and water discarded. All miscible solvent is recovered for recycle.

Abstract: A process for the removal and recovery of sulfur oxides from gas streams by contacting the gas stream with an aqueous suspension of melamine whereupon a mixture of solid, hydrated melamine sulfites, hydrated melamine sulfate is formed. The solids are separated from the reaction product and the clarified liquid recycled. The solids are then heated to temperatures up to 200.degree. C. to decompose the hydrated melamine sulfites into free melamine, gaseous water, and sulfur dioxide, and the gaseous water and sulfur dioxide withdrawn as product. The hot solids are cooled and split into two portions. One portion is recycled and the other portion is treated with a base stronger than melamine to decompose the contained melamine sulfate into free melamine and a basic sulfate salt solution. The basic sulfate salt solution is separated from the melamine and withdrawn as product and the melamine is recycled to the process.

Abstract: A method of preparing dicalcium phosphate from phosphate rock wherein the rock is treated with a mixture of water, carbonyl, and sulfur dioxide. Solids are separated from the liquid phase. The solid phase consists of a mixture of gangue, and calcium .alpha.-hydroxysulfonate. Carbonyl and part of the sulfur dioxide are recovered from the solid by low temperature thermal decomposition. Dicalcium phosphate is precipitated from the liquid phase by partial distilling of SO.sub.2. All carbonyl is recovered for recycle.

Abstract: Ammonium polyphosphates are prepared by a process which comprises heating melamine orthophosphate prepared from impure wet-process phosphoric acid in a stream of gaseous ammonia at a temperature between 150.degree. C and 210.degree. C to produce a mixture of melamine and relatively pure short-chain ammonium polyphosphates. The solid product is extracted with water to remove the ammonium polyphosphates and free the insoluble, crystalline melamine for recycle. Thus, the only starting materials consumed in the process are phosphoric acid and ammonia.

Abstract: Our invention relates to an improved process for the partial purification of wet-process phosphoric acid with co-production of impure phosphoric acid or solid fertilizer materials containing most of the impurities originally present in the crude acid. The crude acid is treated with methanol and ammonia to precipitate most of the metallic and fluorine impurities as solid ammonium metallic phosphates and fluorine compounds that filter and settle rapidly. The solids are separated from the reaction mixture and methanol is distilled from the resulting clarified solution to form concentrated partially purified acid. The solid ammonium metallic phosphates are fertilizer materials. Alternately, the reaction slurry is separated into a clarified liquid fraction and a settled slurry fraction. Methanol is distilled from the settled fraction which causes most of the impurities to redissolve yielding an impure phosphoric acid.

Abstract: My invention relates to a new method for purification of wet-process phosphoric acid with co-production of nitrogen solution. The crude acid is treated with urea by known processes to form urea phosphate free of most of the impurities in the crude acid. The urea phosphate is treated with concentrated nitric acid to form solid urea nitrate and phosphoric acid. The purified phosphoric acid is separated from the urea nitrate and withdrawn as product. The urea nitrate is washed with concentrated nitric acid and the wash soluton then is used for reaction with urea phosphate. The washed urea nitrate is then treated with ammonia and water to form nitrogen solution.

Abstract: dicalcium phosphate is prepared from phosphate rock by a process which comprises reacting phosphate rock with sulfur dioxide and an organic carbonyl compound for 0.5 to 10 hours while maintaining the temperature of the reaction mixture below 50.degree. C. The reaction yields a mixture of gangue, solid calcium .alpha.-hydroxy sulfonate and soluble dicalcium phosphate. The solids are separated from the liquid and P.sub.2 O.sub.5 values adhering to the solid are washed free with a mixture of carbonyl, water, and sulfur dioxide. The wash effluent is recycled to the process and both carbonyl and some sulfur dioxide are recovered from the filter cake by heating it. The offgas from the heated filter cake is recycled to the process and the dry filter cake, now largely calcium sulfite hemihydrate, is discarded.Dicalcium phosphate is precipitated from the reaction mixture filtrate in high yield by partially distilling sulfur dioxide from the filtrate.

Abstract: a method of recovering uranium from wet-process phosphoric acid wherein the acid is treated with a mixture of an ammonium salt or ammonia, a metallic reducing agent such as iron, aluminum or zinc, and then a miscible solvent such as methanol. The precipitated solids, which are separated from the purified phosphoric acid, consist of a mixture of metal phosphates and uranium. This solid is dissolved in acid and the uranium recovered from the solution by liquid-liquid solvent extraction. The miscible solvent and some water are distilled away from the purified phosphoric acid. The distillate is rectified, the water discarded, and the miscible solvent recovered for recycle.When the miscible solvent is methanol, the optimum ranges of ammonia and methanol are 0.05 to 0.20 gram atom nitrogen per gram atom phosphorus and 1.93 to 3.15 pounds methanol per pound of orthophosphoric acid. The amount of reducing agent added should be sufficient to reduce all uraniun to U(IV).

Abstract: a process for the removal and recovery of sulfur oxides from gas streams by contacting the gas stream with an aqueous suspension of melamine containing an oxidation inhibitor such as para-phenylenediamine whereupon a mixture of solid, hydrated melamine sulfites and solid, hydrated melamine sulfate is formed. The solids are then separated from the reaction product and the clarified liquid recycled. The solids are then heated to temperatures up to 200.degree. C to decompose the hydrated melamine sulfites into free melamine, gaseous water, and sulfur dioxide, and the gaseous water and sulfur dioxide withdrawn as product. The hot solids are cooled and split into two portions. One portion is recycled and the other portion is treated with an aqueous inorganic base stronger than melamine such as ammonia or potassium hydroxide to decompose the contained melamine sulfate into free melamine and a basic sulfate salt solution.

Abstract: a process for the production of high-purity urea-ammonium polyphosphate fertilizers from crystalline urea orthophosphate derived from the reaction of wet-process acid and urea. Initially, urea phosphate was pyrolyzed in one stage to give molten urea-ammonium polyphosphates that contained up to 95 percent of the phosphate as polyphosphate, dependent upon the reaction conditions used. Heat to effect condensation of orthophosphate with urea to form polyphosphate was provided by steam. Reaction conditions ranging from a retention time of 1 minute at 350.degree. F to 30 minutes at 260.degree. F were satisfactory. The pyrolyzate contained mixtures of urea, ammonium orthophosphate, and ammonium polyphosphates and was dissolved in aqua ammonia to yield clear liquid fertilizers containing 12 to 15 percent nitrogen and 18 to 29 percent P.sub.2 O.sub.5. Addition of either urea to the process to maintain a urea:biuret ratio of at least 16, or about 2 pounds NH.sub.3 per unit P.sub.2 O.sub.

Abstract: A method of selectively extracting calcite and dolomite away from apatite in phosphate rock or phosphatic limestone wherein the phosphate rock or phosphatic limestone is treated with a mixture of sulfur dioxide, water, and a carbonyl compound. Solids are separated from the liquid phase. The solids consist principally of apatite admixed with clay, quartz, and other accessory minerals originally in the rock. The solids are heated to drive off adhering sulfur dioxide, water, and carbonyl. The liquid phase consists of carbonyl, water, sulfur dioxide, and magnesium and calcium ions. Heating this liquid preferentially precipitates CaSO.sub.3.1/2H.sub.2 O. This solid is filtered off and the filtrate further heated to precipitate MgSO.sub.3.3H.sub.2 O largely free of CaSO.sub.3.1/2H.sub.2 O. All offgas and filtrate is returned to the process. Examination of extraction results shows that high temperature extraction favors dolomite extraction and low temperature extraction favors apatite extraction.

Abstract: Embodiment No. 1. Urea phosphate prepared from wet-process phosphoric acid is heated with monopotassium orthophosphate in a mole ratio of 0.25 to 4.0 at 130.degree. to 200.degree. C. to form an ammonium potassium polyphosphate having an average chain length between 1.2 and 2.5. The ammonium potassium polyphosphate is dissolved in aqueous ammonia to yield concentrated fertilizer solutions containing the three major nutrients and over 50 percent total plant food.Embodiment No. 2. Phosphoric acid containing 54 to 76 percent P.sub.2 O.sub.5 is heated with urea (urea:H.sub.3 PO.sub.4 mole ratio 0.5 to 2.0) and monopotassium orthophosphate (urea:KH.sub.2 PO.sub.4 mole ratio 0.25 to 4.0) at 130.degree. to 200.degree. C. to form an ammonium potassium polyphosphate having an average chain length between 1.2 and 2.5. The ammonium potassium polyphosphate is dissolved in aqueous ammonia to yield concentrated fertilizer solutions containing the three major nutrients and over 50 percent total plant food.