Uhde Gmbh

Friedrich Uhde Gmbh

Wilhelm Wengeler

Friedrich Wolstein

Egbert Hoffmann

Uwe Faust

Rudolf Knecht

Wolfgang Lautenschlager

Ferdinand Holtmeier

The method for the treatment of phosphate rock that has a content of magnesium compounds in excess of 0.3%. The crushed and screened phosphate rock is mixed with water in a ratio of 1:5 by weight. The mixture is acidified with sulphuric acid, and the reaction mixture is filtered and washed before the neutralization point is reached.

Method for the treatment of phosphate rock

Magnesium-bearing phosphate rock in small grain size is converted into phosphoric acid so that no by-products, which are difficult to dispose of are produced. The crushed rock is mixed with water and subsequently acidified with nitric acid, the reaction product being filtered and washed before the neutralization point is reached. The wet and filtered rock is treated with nitric acid to form phosphoric acid and a slurry of calcium nitrate tetrahydrate. The previously formed filtrate is mixed with the calcium nitrate tetrahydrate slurry and this mixture is reacted with ammonia and carbonic acid to form ammonium nitrate, magnesium carbonate and calcium carbonate, which are then separated into an ammonium nitrate solution and a mixture of magnesium and calcium carbonates.

Method for the conversion of phosphate rock containing magnesium into

Freshly mined phosphate rock is subjected to screen classification in at least two stages. Only coarse grained phosphate rock with a grain size over 2 mm from the last screen classification step is fed to a plain-roller grinding mill. The rollers of the grinding mill run at different peripheral speeds, so that the grains are ground by radial and tangential forces. This produces a fine grained phosphate rock whose natural moisture content is advantageous when further processed to phosphoric acid by means of sulphuric acid.

Process for reducing the grain size of phosphate rock

An apparatus for the fermentative conversion of a nutrient mixture by means of microorganisms in the presence of a gas containing oxygen. The nutrient mixture and gas are mixed to yield a phase state with a relative density of less than 0.3 referred to water. The process is carried out in a closed reaction vessel having inlet and outlet pipes for the nutrient mixture, its components and the product. The vessel is also provided with inlet and outlet pipes for the oxygen-bearing gas. A paddle wheel within the vessel provides the distribution device.

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Bochum-Stiepel, Germany

Wilhelm Wengeler