H.c. Starck Gmbh

H. C. Starck, Gmbh & Co Kg

H.c. Starck Tungsten Gmbh

Michael Erb

Juliane Meese-Marktscheffel

Viktor Stoller

Armin Olbrich

Michael Lohse

Frank Schrumpf

Wolfgang Mathy

Gerhard Gille

Klaus-Jürgen Marschall

Josef Schmoll

Sven Albrecht

Matthias Jahn

Rüdiger Zertani

Gerd Maikowske

Benno Decker

Karl-Heinz Heine

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

A method for preparing ammonium heptamolybdate with the steps of:

Method for producing ammonium heptamolybdate

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

A process for preparing nickel hydroxide by alkaline precipitation from nickel salt solutions in the presence of complexing agents, in which the precipitation is carried out at at least two different locations in the same mother liquor with different precipitation kinetics at the different locations and the mother liquor is mixed prior to agglomeration of the precipitated primary crystals, is described.

Nickel hydroxide and method for producing same

A process for reducing the content of alkali metal impurities (e.g., potassium) in ammonium metallate solutions is described. The process involves subjecting a feed solution containing ammonium metallate and alkali metal impurities to membrane filtration. The membrane filtration results in the formation of a retentate having a reduced level alkali metal relative to the feed solution, and a permeate containing substantially the balance of alkali metal. The permeate may also be further treated, to remove alkali metal there from, by passage through a cation exchange column, thereby forming a cation exchange treated permeate that may be combined with the retentate of the membrane filtration step.

Purification of ammonium metallate solutions

A process for elution of rhenium adsorbed on strongly basic ion-exchange resins by means of highly concentrated aqueous hydrochloric acid solution is described, in which the ion-exchange resin is treated with aqueous solution containing an oxidizing agent.

Process for isolating rhenium

A nickel hydroxide for rechargeable batteries which is provided with a cobalt hydroxide coating which is stable to oxidation is described. The stability to oxidation is achieved by covering the surface of the cobalt hydroxide layer with anions of weak inorganic oxygen acids.

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Salzgitter, Germany

Michael Erb