Imi Tami Institute for Research and Development Ltd.

Imi Tami Insitute for Research and Development

Michael Bonan

Ron Frim

Eyal Barnea

Eyal Ginzberg

Gideon Friedman

Akiva Mozes

Hugo Keselman

Cornelis Petrus Langeveld

A process for producing KNO3 from polyhalite to is disclosed. In a preferred embodiment, the process comprises steps of (a) contacting polyhalite with HNO3; (b) adding Ca(OH)2 to the solution, thereby precipitating as CaSO4 at least part of the sulfate present in said solution; (c) precipitating as Mg(OH)2 at least part of the Mg2+ remaining in said solution by further addition of Ca(OH)2 to the remaining solution; (d) concentrating the solution, thereby precipitating as a sulfate compound at least part of the sulfate remaining in solution; (e) separating at least part of the NaCl from the solution remaining; and (f) crystallizing as solid KNO3 at least part of the K+ and NO3-contained in the solution. The process enables direct conversion of polyhalite to KNO3 of purity exceeding 98.5% and that is essentially free of magnesium and sulfate impurities.

[object Object]

A method for the production of KNOfrom polyhalite is provided. The method comprises steps of decomposing said polyhalite into syngenite, gypsum, and soluble components, treating the solid decomposition products sequentially with HNOand Ca basic compound, precipitating the CaSOthus formed, and crystallizing the KNOfrom the solution remaining. The method recovers up to 75% of the potassium present in the raw polyhalite as KNOand substantially all of the remainder as a potassium magnesium sulfate salt.

Process for production of commercial quality potassium nitrate from polyhalite

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Rekhasim, Israel

Michael Bonan