H.c. Starck Gmbh

H. C. Starck, Gmbh & Co Kg

H.c. Starck Tungsten Gmbh

Michael Lohse

Juliane Meese-Marktscheffel

Viktor Stoller

Michael Erb

Frank Schrumpf

Wolfgang Mathy

Klaus-Jürgen Marschall

The invention is directed to ammonium paratungstate decahydrate containing at least 75% of crystals having a length of at least 200 &#x3bc;m and having a ratio of length to width of less than 4.5:1.

Ammonium paratungstate hydrates and ammonium paratungstate decahydrate

The invention is directed to a method for the production of ammonium paratungstate tetrahydrate by thermal treatment of ammonium paratungstate decahydrate in an aqueous suspension. The ammonium paratungstate tetrahydrate can be produced with high purity and high yield. The production method may furthermore be carried out in a simple and energy-efficient manner.

Method for production of ammonium paratungstate tetrahydrate and highly pure ammonium paratungstate tetrahydrate

The invention is directed to a process for the continuous preparation of ammonium paratungstate hydrate by back reextraction of a tungsten-laden organic phase with an ammonia-containing aqueous solution in a mixer-settler apparatus. The reextraction is carried out at an NH:W molar ratio of from 0.83 to 1.30, and a volume feed ratio of the tungsten-laden organic phase to the ammonia-containing aqueous solution of from 5 to 25. The above crystalline is in high purity and in high yield. The production method can be carried out in a simple and energy-efficient manner.

Method for producing ammonium paratungstate hydrates and ammonium paratungstate decahydrate

Sodium tungstate preparation process

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Goslar, Germany

Michael Lohse