The invention relates to calcium hydroxyapatite particles having been sintered at a certain temperature range and which are not treated at a temperature above this range. Furthermore, the present invention relates to an injectable composition comprising such particles and to uses thereof. Surprisingly, it was found that the particles of the invention are superior over calcium hydroxyapatite particles known in the art with respect to bio-stimulation.

The present invention provides that powder is mainly constituted from secondary particles of hydroxyapatite. The secondary particles are obtained by drying a slurry containing primary particles of hydroxyapatite and aggregates thereof and granulating the primary particles and the aggregates. A bulk density of the powder is 0.65 g/mL or more and a specific surface area of the secondary particles is 70 m.sup.2/g or more. The powder of the present invention has high strength and is capable of exhibiting superior adsorption capability when it is used for an adsorbent an adsorption apparatus has.

Embodiments described herein provide systems and methods for a phosphate processing system with integrated sub-systems, such as a phosphoric acid plant, precipitation system, crystallizer system, rinsing system, granulation system, pond water system, organics removal system, and/or exhaust treatment system. Such sub-systems can be integrated with each other by using one or more output streams from one or more sub-systems as one or more input streams for one or more sub-systems. In some embodiments, the phosphate processing system can produce phosphoric acid, struvite containing fertilizer, fertilizer using recycled struvite, magnesium or fluoride containing compositions using recycled magnesium or fluoride, and other components using phosphoric acid collected from a phosphoric acid and gypsum composition or using sludge collected from a waste stream, for example.

This disclosure relates to a method for the preparation of calcium monohydrogen phosphate comprising an etching in an aqueous medium, during a predetermined time period, a source of phosphate with an acid with formation of a pulp comprising an aqueous phase containing calcium phosphate in solution and a solid phase containing impurities, a first separation between said aqueous phase and said solid phase, during a predetermined time period, a neutralization of said aqueous phase at a sufficient pH to obtain a precipitation of said calcium monohydrogen phosphate, a second separation between said aqueous medium and said calcium monohydrogen phosphate, characterized in that said predetermined time period of said step a) of digestion is greater than that of said step b).

This present invention disclosure relates to a method for the preparation of calcium monohydrogen phosphate comprising an etching in an aqueous medium, during a predetermined time period, of a phosphate source with an acid with formation of a pulp comprising an aqueous phase containing calcium phosphate in solution and a solid phase containing impurities, a first separation between said aqueous phase and said solid phase, during a predetermined time period, a neutralization of said aqueous phase at a sufficient pH to obtain a precipitation of said calcium monohydrogen phosphate, a second separation between said aqueous medium and said calcium monohydrogen phosphate, characterized in that said first separation of said step b) is carried out at a filtration rate of at least 0.1 ton of P.sub.2O.sub.5/P/m.sup.2/day.

The invention concerns a method of treating phosphate-containing waste, in particular phosphate-containing ash from waste-incineration plants, by wet-chemical digestion in order to obtain compounds of aluminum, calcium, phosphorus and nitrogen.

In order to provide a hydroxyapatite that can be used without reservation in the food industry, a hydroxyapatite powder is provided composed of primary particles. The median size of the primary particles from which the powder is made is >0.10 ?m and the aspect ratio of the primary particles is <5. The specific surface area of the hydroxyapatite powder is ?10 m.sup.2/g, and the bulk density is >550 g/l. Also disclosed is a method with which such a hydroxyapatite powder can be obtained.

The present invention relates to a composition for the protection against solar radiation, consisting of an organic matrix, preferably a gelatin, and hydroxyapatite nanoparticles modified by the substitution of part of the phosphorus with titanium, and part of the calcium with iron.

In the present invention, the pH of a solution in a reactor is controlled to be 5 or less so that hydroxyapatite crystals cannot be stably present in order to prevent hydroxyapatite from being generated during preparation of whitlockite. To this end, a basic solution containing calcium ions and magnesium ions was added to an acidic phosphoric acid solution to control that the pH of the solution in the reactor does not exceed 5. As a result, whitlockite having very high purity could be synthesized within a very short time.

Herein is described a method for the manufacture of a charge director comprising a barium salt. The method comprises reacting barium alkoxide with an acid in a reaction medium comprising ethanol, and separating ethanol from the reaction mixture to recover the barium salt produced.