Basf Aktiengesellschaft

Hans H Reich

Manfred Ohlinger

Werner Steck

Bernd Leutner

Werner Loeser

Eckhard Hetzel

Horst Autzen

Hansjoerg Siegle

A multistage process for preparing pure BF.sub.3 from hexafluorosilicic acid, H.sub.2 SiF.sub.6, comprises reacting H.sub.2 SiF.sub.6 with oxygen acids of boron and/or boron oxide in the first stage to give hydroxyfluoroboric acid and silica, filtering off the silica and concentrating the hydroxyfluoroboric acid, adding oleum to the concentrate and then heating to form gaseous BF.sub.3.

Preparation of pure boron trifluoride

A process for the preparation of acicular ferromagnetic metal particles, consisting essentially of iron, by reducing acicular iron oxides and/or iron oxide hydroxides, which are either pure or are modified with conventional foreign metal ions, by means of a gaseous reducing agent in a fluidized bed furnace in which a stirrer is provided immediately above the fluidizing grid.

Preparation of acicular ferromagnetic metal particles consisting

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Ludwigshafen, Germany

Hans H Reich