Agitating – Having interrelated feed and discharge means – Recirculating from and to mixing chamber
Reexamination Certificate
1998-08-28
2001-10-23
Soohoo, Tony G. (Department: 1723)
Agitating
Having interrelated feed and discharge means
Recirculating from and to mixing chamber
Reexamination Certificate
active
06305833
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved process for producing solids by precipitation in a mixer to form a mixture of solid and liquid.
Various apparatuses and processes for producing solids by precipitation are known. Reactions of this type are frequently carried out in stirred vessels. Such processes are described in detail, for example, in O. Soehnel, J. Garside: Precipitation; Butterworth Heinemann, Oxford, 1992. Besides the complexity and cost of operating such processes, the relatively long residence times also prove to be disadvantageous. Furthermore, the existing possibilities for controlling such processes are inadequate.
EP-B 0 655 984 describes a process for producing solids by mixing two liquids, these liquids being fed together under high pressure into a decompression apparatus.
The decompression in mixing chambers of various designs dissipates the power introduced with the pressure and uses it for mixing. However, in this case high local temperature peaks occur and may result in damage to the product or formation of unwanted phases. Furthermore, signs of cavitation may occur in this elaborate high-pressure process and cause further damage to the product.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to find an improved process for producing solids by precipitation in a mixer to form a mixture of solid and liquid, which remedies said disadvantages and makes possible to produce solids of high quality in a simple and economic process. It is further intended that the novel process parameters and, in the event of fluctuations which may occur, for example, when the starting materials are changed, can be adjusted easily and rapidly.
We have found that this object is achieved by a process for producing solids by precipitation in a mixer to form a mixture of solid and liquid, which comprises feeding the starting materials into a mixing apparatus which has essentially a rotationally symmetrical mixing chamber which has a rotor disposed therein and is formed by a peripheral wall and two end walls, and where
a) the starting materials are each fed to at least one inlet opening in the peripheral wall of the mixing chamber, and
b) the solid-containing mixture which is formed is removed from at least one outlet opening in the peripheral wall of the mixing chamber.
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Precipitation, Soehnel, Butterworth, Chapter 7, pp. 269-272.
Horn Hans Christoph
Kumberger Otto
Millies Marco
Neth Norbert
Popel Wolfgang Jurgen
BASF - Aktiengesellschaft
Keil & Weinkauf
Soohoo Tony G.
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