Gas and liquid contact apparatus – Contact devices – Injector type
Patent
1988-07-21
1989-06-20
Miles, Tim
Gas and liquid contact apparatus
Contact devices
Injector type
261DIG75, 209170, B01F 304
Patent
active
048407534
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for aerating liquids or fluids, especially during flotation, and is embodied as a ring injector, in the housing of which, through which the fluid flows, there is disposed a middle piece that forms an annular channel with the housing, whereby at the level of the air discharge openings in the wall of the housing, the annular channel has its narrowest cross-sectional area; following this narrowest location of the annular channel in the direction of flow of the fluid, the annular channel undergoes a sudden increase in cross-sectional area, adjoining which a mixing and dispersing section leads to the outlet of the housing.
Devices of this type are known, and are used, for example, during flotation in order to separate the solid materials contained in a slurry from one another. The difficult-to-moisten solid particles are deposited on air bubbles that are generated in such devices, which are also known as gasifiers, injectors, or reactors. The solid material deposited on the air bubbles is generally discharged over the edge of the separating or flotation vessel.
With all aerating devices of this type it is desirable to keep the size of the air bubbles as small as possible, because this facilitates the deposition of solid particles during the flotation.
A device for mixing gases and liquids was already disclosed 50 years ago in U.S. Pat. No. 1,810,131. This device shows features of an aerating device such as was later disclosed (DE-OS No. 34 12 431) as a device for aerating dispersions, especially as a flotation device for delivering fibrous material suspensions or dispersions with a ring injector.
Air is supplied to the ring injector via air supply passages in the mixing section. As a result, the annular gap formed in the ring injector is aerated on the inside and the outside. The mixing section and the middle piece, which is centrally disposed within the mixing and dispersing section, are stepped, as a result of which, similar to a water-jet pump, the air is drawn into the inner and outer regions of the dispersion stream that is formed.
It is an object of the present invention to substantially improve devices of the aforementioned general type so that the specific energy consumption is reduced and the degree of selectively is increased.
This device should be especially suitable for the flotation of coal and other preparation material.
SUMMARY OF THE INVENTION
To realize this object, it is proposed pursuant to the present invention that the aerating device of the aforementioned general type have, as the slurry enters the aeration chamber, a gap width that leads to a minimum slurry speed V.sub.1 of 2.0 m/s. The middle piece of the device extends to the outlet of the housing and the diameter remains constant. The annular channel has the same cross-sectional area from the sudden increase to the outlet of the housing, and the length of the mixing and dispersion section is more than 20 times the annular gap width of the annular channel.
Due to the uniform speed in the annular channel resulting from the constant cross-sectional area, the thorough mixing of air bubbles and solid material particles during the course of the mixing section is particularly favorable, since during the course of the entire mixing section the specific energy input is constant.
Tests in a coal-flotation plant have shown that at a slurry speed of greater than 2 m/s, especially at 2.0 to 4.0 m/s, the yield is optimum.
Further structural details will be described in detail subsequently.
The splitting of the core or essential portion of the aerating device into the distributing cone and the middle piece, which can be screwed together or inserted into one another, makes it possible to combine different distributing cones and middle pieces. Depending upon the requirements, it is possible to use distributing cones having different diameters of the base of the straight circular cone, and/or cones having different angles between the base and the side lines of the circular cone, i
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Jungmann Andreas
Reilard Ulrich
Allmineral Aufbereitungs-technik GmbH & Co. KG
Miles Tim
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