FR2474344A1 - ROTARY DEVICE FOR CLASSIFYING SOLIDS FROM THEIR SUSPENSIONS - Google Patents

Abstract

THE INVENTION RELATES TO A DEVICE, OF THE CENTRIFUGAL TYPE, FOR THE CLASSIFICATION OF FINE GRAINS IN SUSPENSION IN A LIQUID THE DENSITY OF WHICH DENSITY DIFFERES LITTLE FROM THAT OF THE GRAINS. TO THE ROTOR 1 OF THE CENTRIFUGE ARE FIXED POCKETS 4, SHAPED BY A REAR WALL 9 AND A CURVED SIEVING SURFACE 8, CONSTITUTED BY BARS 12 CONTAINING SLOTS 13 FOR THE PASSING OF FINES. THE FRACTION COLLECTED IN SPACE 10 EXITS THROUGH NOZZLE 11. APPLICATION TO GRADING OF GRAINS OF 0.05 TO 0.5MM.

Description

1 2474344

  The invention relates to a device for the classification of solids, preferably having fine grains, in the range or the separation range of 0.05 to 0.5 from suspensions, in particular suspensions having a small difference in density between the solid and liquid phases, using pockets with slotted surface separation or bag-sieves subjected to a

  rotor rotatable about a vertical axis.

  The classification of the solids from their suspension can be carried out by sedimentation or by sieving. For sedimentation, however, there must be a sufficient difference in density between the fluid phases

  and solid. With known devices, such as a hydro-

  cyclone and decanting centrifuges, it is only possible to obtain a sufficiently sharp classification up to a particle size of about 0.08 mm. Therefore, and assuming a sufficient difference in density, these

  devices are only suitable for the finest beach.

  It is also possible to classify a suspension using a hydrocyclone only if the fluid phase constitutes a significant proportion of the suspension, so that in many cases it is necessary to add further

  liquid to achieve the ranking.

  With the known sieving machines, one does not

  can perform rankings with satisfactory data rates.

  only from a particle size limit

about 0.5 mm.

  For the separation domain lying

  between 0.08 and 0.5 mm, all that remains is sediment

  tation, which is expensive in the case, which often occurs, o large enough quantities are to be treated and which requires a lot of space, or it can be sieved only with a specific yield

limit.

  With a perforated-pocket centrifuge as described for example in DE-AS 1,119,775, only separation of water and granular material can be achieved. Known perforated-pocket centrifuges are unsuitable for solids classification with clear separation, as is often required in industrial technology to be able to then subject the product streams thus obtained to other specific processes.

treatment.

  The present invention therefore aims to provide, particularly for the range of particle sizes between 0.05 and 0.5 mm, a robust and high-speed device for the net classification of solids from their suspension1 without it. must be

  difference in density between the solid and the liquid.

  In order to solve the problem thus posed, the filing device according to the invention comprises pockets with a split surface of separation, having the form of a curved sieve and having bars arranged.

  transversely to the direction of centrifugation

  and delimit sieving slots. Thus, not only are the flow rate and range characteristics of the classification, which are insufficient for the known static curved sieve, improved, but the possibility of application to suspensions which have only a zero or a low density difference is also widened.

between the solid and the liquid.

  In a particularly advantageous way,

  sieving bars are made of resistant material

  both for wear such as, for example, titanium carbide, tungsten carbide or a ceramic material, or at least these bars are coated with such material. The classification can also be divided into several beaches when the space behind the slotted sieving surface comprises chambers each of which allows a clear separation between the beaches or

ranking domains.

  A non-limiting embodiment of a device of the invention will now be described

  in more detail with reference to the annexed drawings on

what:

  FIG. 1 is a section of a rotor comprising

  both pockets with slotted surface separation or pockets-

  sieve; Figure 2 is a section along the line II-II of Figure 1; Figure 3 is a view of the slotted surface of separation of a pocket made in the form of a curved screen; and FIG. 4 is a section along the line

IV-IV of Figure-3.

  FIGS. 1 and 2 show a rotor 1 which a motor 3 can drive with the aid of a shaft 2 and to which pockets 4 with a split slit surface, made in the form of a curved sieve, are secured. A perforated intake manifold 5 is disposed in the center of the rotor 1 and can be conveyed by means of a nozzle

  7, connected to an envelope 6, the suspension

  to be classified. The pockets 4 are constituted by a slotted surface 8 of separation and by a rear wall 9 delimiting a space 10 where the classified material can

exit by nozzles 11.

  The surface 8 has a concave curvature and, as is apparent from FIGS. 3 and 4, this surface 8 is formed of bars 12 of trapezoidal section, which delimit between them slots 13. In use, the suspension to be classified is conveyed by via the inlet distributor 5 on the surfaces 8 of the curved screen-shaped bags 4 and flows over the transverse slots 13. It is thus possible to obtain, with good flow rates, clear separations for suspensions having zero differences.

  or low density between the solid and liquid phases.

  This device makes it possible in particular to perform class-

  precise and high-performance

  grain sizes from 0.05 to 0.5 mmIn.

  Thus, in a test with a suspension of charcoal in water, the following classification was obtained: 0 Size of> 0.41> 0.2> 0.1> 0.041> 0, 03 I> 0.02 grains in mm Percentage appearing in fraction 53 84.4 92.3 98.2 100 coarse Percent1 ge l I t Percentage appearing in fraction 0 18.7 40 56.9 59.8 68.4 fine separation For a slit width of 0.3 mm, a clear separation in the grain size range of 0.2 mm is obtained: 84.4% of the solid constituents of the coarse fraction have a grain size greater than 0 2 mm and 81.3% of the solid components of the fine fraction have a grain size less than 0.2 μm, i.e. 18.7% have a grain size greater than 0.2 min. These separation values represent an extraordinarily good grading efficiency, especially considering that coal has a density of only 1.35 kg per dm3. It should also be pointed out that in this test, the charcoal has been introduced into the k474344 classification device according to the invention at the rate of 600 g of solid charcoal per liter of water, whereas for other

  processes, at least 150 g of

  good per liter of water for passive results.

  good ranking. The classification may also be divided into other ranges when the space 10 is subdivided into two or more compartments (not shown), each of these compartments must then comprise a nozzle

  particular for the separate exit of the various fractions

corresponding statements.

  It goes without saying that, without departing from the scope of the invention, many modifications can be

  made to the device described and shown.

Z474344

Claims (3)

-REVENDICATIONS   1. Device for the classification of solids preferably having fine grains, in the range or the separation range of 0.05 to 0.5 mm, from suspensions, in particular suspensions having a small difference in density between the phases solid and liquid, using slotted surface pockets fixed to a rotor rotatable about a vertical axis, this device being characterized in that the pockets (4) are made in the manner of a curved screen comprising bars (12) arranged transversely to the direction of centrifugation and delimiting slots (13) allowing sieving.   2. Device according to claim 1, characterized in that the bars (12) consist of a material resistant to wear or are coated with a such matter.   3. Device according to claim 1, characterized in that, to allow to obtain several ranges of classification, the space (10) located behind the bars (12) is subdivided into at least two compartments, each of which comprises a nozzle separate output.