Abstract: The present invention relates to a process for the manufacture of disodium phosphate of a high purity without utilizing organic solvents. According to the process, monosodium sulfate is reacted, at a temperature, in the range of 40 to 100 degrees C. with a phosphate constituent selected from phosphate rock, dicalcium phosphate or mixtures thereof, in the presence of phosphoric acid. The common metal impurities, organic matter and fluorides present in the starting phosphate rock are substantially complete eliminated with the solid gypsum or dicalcium phosphate resulted thereto. After separating said solid, the filtrate is treated in two neutralization stages: first by a calcium constituent selected from calcium carbonate, calcium hydroxide or mixtures thereof and separating the formed dicalcium phosphate, followed by a second neutralization with an alkali sodium constituent selected from sodium hydroxide, sodium carbonate and sodium bicarbonate or mixtures thereof at a pH in the range of 8.0 to 9.5.

Abstract: The present invention relates to a process for the manufacture of monopotassium phosphate of a high purity without utilizing organic solvents. According to the process, monopotassium sulfate is reacted, at a temperature in the range of between 40 to 100 degrees with a phosphate constituent selected from phosphate rock, dicalcium phosphate or mixtures thereof in the presence of phosphoric acid. The common metal impurities, organic matter and fluorides present in the starting phosphate rock are substantially elininated, with the calcium sulfate resulted thereto. After separating out the calcium sulfate, the filtrate is neutralized to a pH in the range of between 3 to 7, with a calcium-containing compound comprising Ca(OH).sub.2, CaO or CaCO.sub.3, or mixtures thereof. From the filtrate obtained, pure monopotassium phosphate is crystallized out. The process is characterized by a high recovery of the P.sub.2 O.sub.5 and K.sub.2 O values, the monopotassium phosphate produced being completely free of chloride ion.

Abstract: The present invention relates to an improved process for the manufacture of purified phosphoric acid from phosphate rock. According to the invention, phosphate rock is decomposed by a mineral acid selected from hydrochloric acid, sulfuric acid or mixtures thereof. The dissolution liquor obtained is reacted with a calcium-containing compound such as calcium oxide, calcium carbonate, tricalcium phosphate and fines of phosphate rock producing an aqueous solution containing monocalcium phosphate in an amount corresponding to between 0.4% to 5.5% by wt CaO. After the separation of the precipitated solids, the clarified solution is extracted by an organic solvent having the property to extract the phosphate component. The phosphoric acid is subsequently recovered from the solvent extract by known methods such as washing or distillation.

Abstract: The present invention relates to a method for beneficiation of phosphate rock by a thermal treatment, wherein an appreciable increase in P.sub.2 O.sub.5 and decrease in cadmium contents in the calcined product are achieved. According to the invention, the phosphate rock is contacted with hot gases possessing a temperature in the range of between 700.degree. C. to 1600.degree. C. for a period of below 60 seconds and subsequently the fines are removed by a conventional classification method thus obtaining an up-graded phosphate product with a relatively low cadmium content. The up-graded phosphate product is also characterized by a relatively low sulfide content as well as low organic matter, which are very advantageous in the phosphoric acid manufacture therefrom. One of the advantages of the method is the almost complete recovery of the P.sub.2 O.sub.5 present in the phosphate rock since no slaking for calcium oxide removal is utilized.