Provided is a method of manufacturing phosphate fertilizer that comprises dicalcium phosphate, the method comprising providing milled phosphorus-containing rock having a total phosphorus content of at least about 15% P by weight, mixing the milled phosphate-containing rock with a mineral acid in a reaction vessel to produce a superphosphate product, and mixing the superphosphate product with a calcium-source reverting agent and a magnesium-source reverting agent to produce a reverted product, the calcium-source reverting agent comprising at least about 20% by weight of the total reverting agent of calcium oxide with a calcium carbonate equivalence of at least about 134%, and the magnesium-source reverting agent providing a magnesium source and comprising at least about 20% by weight of the total reverting agent of magnesium source with a calcium carbonate equivalence of at least about 80%, to produce a granulated cured reverted product having a product yield of at least about 1.90 or of at least about 1.77, and a moisture content of less than 3%.

Process of acid attack with sulphuric acid of a phosphate source comprising calcium or not comprising calcium for a predetermined time period ranging from 20 to 180 minutes in the conditions wherein the molar ratio of sulphate from the sulphuric acid and possibly from the phosphate source to the calcium present in the phosphate source ranges from 0.6 to 0.8, and the content in P.sub.2O.sub.5 in the attack tank is of less than 6%.

A method and apparatus of preparing lithium compound(s) from lithium-containing mineral includes a) a leaching step, wherein the lithium-containing mineral is leached in aqueous leach solution containing alkaline carbonate, for liberating lithium and phosphate(s) from the lithium-containing mineral, thus obtaining leach slurry containing lithium carbonate and phosphate(s) leach slurry, b) a carbonization step, wherein the leach slurry containing lithium carbonate and phosphate(s), obtained from the leaching step, is reacted with an alkali earth metal compound in the presence of CO.sub.2 for obtaining a carbonated slurry containing lithium hydrogen carbonate, and for precipitating phosphate(s) contained in the leach slurry as insoluble phosphate compound(s), c) a solid-liquid separation step, wherein the carbonated slurry obtained from carbonization step is subjected to solid-liquid separation wherein the undissolved mineral and phosphate compound(s) are separated as solids that can be recovered or discarded, thereby obtaining a solution containing lithium hydrogen carbonate.

A method for the precipitation of rare earth sulphate, the method including subjecting a crude rare earth sulphate solution to precipitation in the presence of a water soluble, volatile, organic compound to produce a rare earth sulphate precipitate and an acidic supernatant. The organic compound is preferably selected from the group consisting of methanol, ethanol, iso-propanol, tert-butanol, acetone or mixtures thereof, and is preferably methanol. Preferably, the organic compound is used in the precipitation at a weight ratio of between 0.25:1 to 1.5:1, and preferably 0.5:to 1.25:1, with the crude sulphate solution.

A method for the precipitation of rare earth sulphate, the method including subjecting a crude rare earth sulphate solution to precipitation in the presence of a water soluble, volatile, organic compound to produce a rare earth sulphate precipitate and an acidic supernatant. The organic compound is preferably selected from the group consisting of methanol, ethanol, iso-propanol, tert-butanol, acetone or mixtures thereof, and is preferably methanol. Preferably, the organic compound is used in the precipitation at a weight ratio of between 0.25:1 to 1.5:1, and preferably 0.5:to 1.25:1, with the crude sulphate solution.

The present invention relates to the method of production of beta-tri-calcium phosphate (-TCP) with high purity and which has an osteoconductive support matrix which can be resorbed and which is bio-compliant when implanted to the defect area and which provides new bone formation in the defect area and which is resorbed while displacing with the newly formed bone in time.

The present invention provides: a method for producing a shaped product comprising octacalcium phosphate and having a volume of 2.0 mm.sup.3 or more, comprising immersing a precursor ceramic composition containing at least one of Ca and PO.sub.4 in composition, having a solubility in H.sub.2O higher than that of octacalcium phosphate, and having a volume greater than 2.0 mm.sup.3, in a solution containing a component which is not contained in the precursor ceramic composition, among the components Ca, PO.sub.4 and H.sub.2O, which are components of octacalcium phosphate to allow the precursor ceramic composition to react, thereby converting at least a part of the precursor ceramic composition into octacalcium phosphate; and the like.

Process of acid attack with sulphuric acid of a phosphate source comprising calcium or not comprising calcium for a predetermined time period ranging from 20 to 180 minutes in the conditions wherein the molar ratio of sulphate from the sulphuric acid and possibly from the phosphate source to the calcium present in the phosphate source ranges from 0.6 to 0.8, and the content in P.sub.2O.sub.5 in the attack tank is of less than 6%.

A method for preparing calcium sulphate comprising a production of DCP by the attack of a source of phosphate by an acid, a digestion of the isolated DCP by the sulphuric acid under conditions giving rise to the formation of a first slurry of gypsum suspended in an acidic aqueous phase having a content of free SO.sub.3 equal to or less than 1.5% and a content of free P.sub.2O.sub.5, a conversion of at least part of said first slurry by heating to a temperature greater than 80 C. and potentially by adding sulphuric acid, with solubilisation of the gypsum crystals and recrystallisation of the solubilised calcium sulphate in a second slurry of -calcium sulphate hemihydrate crystals suspended in an aqueous phase based-on phosphoric acid, wherein the content of free SO.sub.3 is less than 10% by weight, and a separation between said aqueous phase and a filter cake based on particularly pure -calcium sulphate hemihydrate.

The present invention provides: a method for producing a shaped product comprising octacalcium phosphate and having a volume of 2.0 mm.sup.3 or more, comprising immersing a precursor ceramic composition containing at least one of Ca and PO.sub.4 in composition, having a solubility in H.sub.2O higher than that of octacalcium phosphate, and having a volume greater than 2.0 mm.sup.3, in a solution containing a component which is not contained in the precursor ceramic composition, among the components Ca, PO.sub.4 and H.sub.2O, which are components of octacalcium phosphate to allow the precursor ceramic composition to react, thereby converting at least a part of the precursor ceramic composition into octacalcium phosphate; and the like.