FR2579575A1 - Apparatus for metering materials or mixtures of material in pulverulent and/or granular form - Google Patents

Abstract

The invention relates to an apparatus for metering materials or mixtures of material in pulverulent and/or granular form, comprising at least one container and metering devices. The container 3 comprises a lower part 5 with a cross-section which decreases downwards and on the base of which is arranged at least one nozzle 12 above which is placed an ejector 13, the nozzle 12 being connected to a carrier-gas conduit 15, whilst the ejector 13 is connected to a mixture-transportation conduit 14. Application to the introduction of alloy or treatment materials into metal baths, particularly baths of steel.

Description

t1 2579575

  APPARATUS FOR DOSING MATERIALS OR MIXTURES OF MATERIALS

  POWDERY AND / OR GRANULAR FORMS

  The present invention relates to an apparatus for dosing materials or mixtures of materials in powder and / or granular forms, firstly for introducing alloying substances or treatment additives into metal baths. The apparatus

  comprises at least one container and a metering device.

  It is known that, during this last decade and following the evolution of metallurgical technologies as well as under the effect of the tendency of metallurgical factories to increase more and more their absorption capacity and their specific productivity, numerous methods for treating steel outside the melting device have been developed. These processes were first applied to

  deoxidation and desulfurization of steel.

  The alloying or quality improvement additives are in powder or granular form and are introduced into the

  fusion bath using injection devices.

  Around the world, there are many different types of injection systems. These can be classified, however, in principle on the basis of their main functions, into two groups, one of which contains mechanical metering devices and the other of which is called

fluidization devices.

  The most important part of fluidization devices operating on the principle of the turbulent bed corresponds to what are called fluidization vessels in which the reagents or treatment materials classified with precision and whose particle size always varies within a range very narrow (0.32-0.63 mm) are converted to the fluid state after introduction and are then injected into the metal bath using a carrier gas using a

  tubular system and a lance coated with a refractory material.

  The systems operating according to this principle have the disadvantage that the pulverulent substances to be introduced must have a narrowly defined particle size which varies only within a reduced interval. As a result, the reagents become very expensive. Another disadvantage is that, under certain conditions, the capacity of the system cannot be adjusted. In addition, powder blowing devices are not suitable in most cases for

  inject mixtures of different materials into the melt.

  In the case of systems operating on the mechanical principle, the

  insufflation capacity can be changed using a mechanical metering device

  than incorporated, usually a dosing tray. These systems are

  subject to less stringent requirements with regard to the granulo-

  metrics but, however, their structure is extremely complicated due to the principle of mechanical operation, their operational safety

  under normal service conditions is insufficient and they require-

  carry out major maintenance and repair work.

  An object of the invention is to develop an apparatus for

  using which materials or mixtures of materials in powder form

  slow and / or grainy, also of heterogeneous particle size, then-

  feels to be dosed, for an adjustable capacity at will.

  This problem is solved in accordance with the invention using a large apparatus at least one container and a metering device and in which the lower part of the container has a profile of decreasing diameter downwards, in particular a conical profile, while

  at least one nozzle is provided on its bottom and, above it

  ci, an ejector, the nozzle or nozzles being connected to a gas pipe

  carrier and the ejector to a mixture transport duct.

  The ejector provided in the metering device is advantageously a two-stage ejector. In the part of the container which decreases in section downwards, a profile filling funnel is provided.

  tapered, advantageously conical, the upper part of which is covered

  green by a metal screen or by a perforated plate. The funnel of

  filling can be connected to a vibrator.

  The container of the apparatus according to the invention can be provided, if necessary, with a built-in scale, advantageously a

electronic scale.

  In an advantageous embodiment of the apparatus according to the invention, the container is connected to at least one hopper

  mixer in which rotating blades are arranged.

  The mixing hopper or the container are advantageously connected to metering containers and the metering containers are provided, respectively, with metering devices. These metering devices are advantageously associated with a control scale. When the apparatus according to the invention is used for

  introduce alloying or treatment materials into a metal bath

  lique, the mixture transport duct is advantageously connected to a blowing lance. The blowing lance consists of a conveying tube provided with ribs on its outer periphery, a casing tube surrounding it, an elastic refractory layer surrounding the casing tube, a refractory coating layer and an outer protection tube. Between the conveyor tube and the envelope tube are advantageously formed passage channels for a

coolant.

  The apparatus according to the invention has numerous advantages.

  compared to conventional solutions.

  By means of the injection container, it is possible to adjust the insufflation intensity over a wide range (10-140 kg / min), to which contribute the vibrator and the nozzles operating with a speed

variable flow.

  Another important advantage of the apparatus is that it is possible to inject or dose particles with a particle size between 0.01 and 4 mm. This means that the materials to be dosed can be prepared under substantially restrictive grinding and screening conditions, in comparison with the materials used.

  usually which must correspond to a grain size to the tolerances

  very narrow rancid. As a result, the grinding devices can be simpler and less expensive and the material to be blown can be

  produced with less handling.

  The equipment can operate with different carrier gases, among others with oxygen, nitrogen or argon. Consequently, the

  range of application of the equipment is greatly expanded.

  Another advantage of the apparatus consists in that it makes it possible to dose any composite mixtures containing materials of different densities. So when introducing substances of

  treatment or alloy in the metal bath, it is always possi-

  ble to select the optimal composition each time. Also, the extremely expensive preparation of the various pre-alloys becomes superfluous. The blowing lance which can be connected to the apparatus also withstands high mechanical and thermal stresses and, consequently, it is possible to adopt extremely long treatment times, of approximately 40 to 50 minutes, without risk of deterioration. ; the blowing lance is suitable even for treatments to be carried out

during casting.

  The apparatus according to the invention is suitable for the rapid and precise implementation of various technological means, with a view to intensifying the processes and, for this reason, increasing

  the specific capacity of equipment in the metallurgical industry.

  With the apparatus according to the invention, it is furthermore -

  it is possible to use, without residue, the fractions of deoxidizing substances

  tes and other additives in the form of pus-

beers or lumps.

  Therefore, correspondence, through the use of the app

  reillage according to the invention, it is possible to achieve significant savings in materials and energy. The precision of the

  steel fabrication is increased, as is productivity.

  Other characteristics and advantages of the invention will be put

  highlighted in the following description, given by way of example

  not limiting, with reference to the appended drawing in which: - Figure 1 schematically shows an embodiment of the apparatus according to the invention; and

  - Figure 2 is a partial sectional view of the container.

  The apparatus shown in Figure 1 is designed for intro

  to coat alloying substances or treatment substances in metallic baths. The apparatus comprises a metering container 1, a mixing hopper 2 and a container 3. The container 3 is shown in FIG. 2. It consists of a cylindrical part 4 and a conical part 5 and it is closed in high by a cover 6. The container 3 is

  mounted on a frame 7. On this frame 7 are arranged electro-

  picnics 8 on which consoles 9 fixed on the wall

side of container 3.

  Inside the container 3, and concentrically to it, is

  arranged, in the conical lower part 5, a filling funnel

  sage 10, also conical in shape. The filling funnel 10 is connected to a vibrator (not shown in the drawing to simplify this) and by means of which the filling funnel 10 can be subjected to vibrations of an appropriate frequency. The upper portion

  of the filling funnel 10 is covered with a metallic screen.

  that 11. Between the upper edge and the lower edge of the filling funnel 10 and the wall of the container 3, there are provided, to prevent material from falling in between, delimiting elements

  made of a preferably elastic material.

  A nozzle 12, the opening of which is directed vertically upwards, is fixed to the bottom of the container 3. Above this nozzle, an ejector 13 is provided, which is connected to a conduit 14 for transporting the mixture. The nozzle 12 is connected via a pipe 15 to a central gas pipeline or else to a gas distributor station

  fitted with pressurized gas cylinders.

  At the ends of the mixture transport duct 14, there is provided

  receptacles 16 in which are blown lances

  ge 17. These lances make it possible to introduce the metal bath into the

prepared mixture.

  The inner part of each blowing lance consists of two concentric steel tubes, namely the transport tube

  provided with ribs on its outer periphery and the tube-envelope.

  The ribs located between the transport tube and the envelope tube provide, on the one hand a suitable mechanical resistance of the structure and, on the other hand, they can be used, if necessary, to define

  channels for a coolant.

  The outer part of the blowing lance 17 consists of

  three layers, namely an elastic layer placed on the tube-

  envelope (and which may be formed for example of a strip of asbestos wound on the tube), of a refractory coating layer disposed on the first layer (and which is advantageously prepared from a self-liquid refractory mass hardening) and an outer tube

  protection made of refractory material.

  The blowing lance 17 arranged in the manner described can operate for 40 to 50 minutes at temperatures above 1800 K, without degrading its refractory quality and its thermal insulation capacity. Also, the blowing lance absorbs well the mechanical stresses generated by the intensive movement of the bath

of molten metal.

  The apparatus according to the invention operates in the following manner: the

  different alloying or treatment substances in powder form

  slow or grainy. The metering containers 1 are advantageously arranged so as to open automatically when they are placed on

  metering stations 23. The quantity of metered material is automatically adjusted

  by the scales installed in the dosing stations. The metered quantities of material reach the mixing hopper 2 o

  they are homogeneously mixed using the stirring blades.

  When it is simply the dosage of two to three materials

  different, it is sufficient to use a mixing hopper 2.

  However, when more material is to be mixed, it is necessary

  be sure to use several mixing hoppers 2, because the number of

  metering containers 1 connected to a mixing hopper 2 is limited.

  When several mixing hoppers 2 are used, it is advantageous to homogenize the mixtures in an additional mixing hopper 2

  before their introduction into the container 3.

  The mixing hopper (s) 2 are advantageously fixed to the

  container 3. The mixture is introduced into container 3 via

  diary of a valve or airlock. After completion of the assay, the reci-

  pient 3 must be hermetically sealed.

  If necessary, the homogeneous mixture can also be prepared from

  any other suitable way and then be introduced into the container.

pient 3.

  The dosage of the desired quantity is controlled by the electronic scales 8 arranged on the frame 7. When the desired quantity of

  material is on the metal screen 11, the dosage can begin.

  This means that the vibrator connected to the filling funnel'10 is activated. Under the effect of vibrations, the mixture passes through the holes of the metal screen 11 to enter the filling funnel 10 and it is distributed uniformly in the gas leaving the nozzle 12 to

  then exit the ejector 13, at the same time as the carrier gas.

  In the embodiment shown in FIG. 1, the mixture and the carrier gas pass through the blowing lance 17 and are

  injected by it into the molten metal bath.

  Compared to the conventional addition of powder mixtures, the apparatus according to the invention has many advantages. An important advantage is that it is not necessary to have a ground material of homogeneous particle size to obtain an accurate dosage,

  so that the manufacture of the powder mixture becomes considerable-

  simpler and less expensive. Because the spray mixtures

  slow dosages generally have a non-homogeneous particle size and contain

  for this reason, also relatively large particles, the conduits are not obstructed because large particles with a high kinetic energy clean the conduits and prevent

obstructions.

  The apparatus according to the invention is suitable for rapid and precise implementation of different technological means, for a

  intensification of processes and, for this reason, for an increase

  tion of the specific capacity of equipment in the steel industry

gic.

  Thanks to the invention, it is considerably simpler to use.

  will also be material in powder form, fragmented during

storage and transport.

  Thanks to the precise and correct dosage and the possibility of preparation

  tion of powder mixtures of any composition, the preparation

  expensive pre-alloys become superfluous because the processing substances

  ment of the desired composition can be dosed directly under

form of powder mixtures.

  It follows that it suffices to introduce, into the bath of molten metal, the strictly necessary quantity of treatment materials and that the excess dosage generally adopted in technologies.

classics is no longer necessary.

  When processing steels, for example, the slag produced in

  the oven no longer has to be removed, or even to be partially renewed.

  Treatment can even begin after the start of casting.

  The implementation of the various treatment methods is practi-

  only independent of the material of the lining of the pocket, which

  translated, by comparison with conventional technologies, by an increase

  tion of the yield and a reduction in costs.

  According to the invention, it is thus possible to carry out a

  dosing of different powder mixtures in a much more efficient way

  cace and much more correct than before. When using these powder mixtures in technologies in the steel industry, the

  different operating processes can be considerably simplified

  operating costs can be reduced in proportion

  important information. In addition, the quality of the products can also be

greatly improved.

  Of course, the present invention is not limited to the modes of

  realization described and represented, but it is likely to nom-

  wide variants accessible to those skilled in the art without being

  departs from the spirit of the invention.

Claims (11)

  1.- Apparatus for dosing materials or mixtures of materials   res in powder and / or granular forms, such as, in particular alloying and treatment substances for metal baths, equipped with at least one container and metering devices, characterized in that the container (3) comprises a part lower (5) of decreasing section downwards and in that there is provided, at its bottom, at least one nozzle (12) and, above this, an ejector (13), the nozzle (12 ) being connected to a carrier gas conduit (15) and the ejector (13) being   connected to a mixture transport pipe (14).   2.- Apparatus according to claim 1, characterized in that   the ejector (13) is a two-stage ejector.   3.- Apparatus according to one of claims 1 or 2, characterized   in that there is provided, in the lower part (5) of the container (3), a filling funnel (12) of decreasing section downwards and the upper opening of which is covered by a metal screen (11) or by a perforated plate.   4.- Apparatus according to claim 3, characterized in that   the filling funnel (10) is connected to a vibrator.   5. Apparatus according to any one of claims 1 to 4,   characterized in that the container (3) is provided with at least one rocker incorporated (8).   6.- Apparatus according to any one of claims i to 5,   characterized in that the container (3) is associated with at least one hopper mixer (2).   7.- Apparatus according to claim 6, characterized in that   rotating blades are arranged in the mixing hopper (2).   8.- Apparatus according to one of claims 6 or 7, characterized   in that the mixing hopper or the container (3) are associated with dosing containers (1).   9. Apparatus according to claim 8, characterized in that   the dosing containers are associated with dosing stations.   10.- Apparatus according to claim 9, characterized in that   the dosing stations (23) are associated with control scales.   11. Apparatus according to any one of claims 1 to 10,   characterized in that the mixture transport pipe (14) is connected to a blowing lance (17).   O10 12.- Apparatus according to claim 11, characterized in that the blowing lance (17) consists of a transport tube provided with ribs on its outer periphery, a tube-envelope surrounding the   aforementioned tube, an elastic refractory layer surrounding the tube-   casing, a refractory coating layer and an outer tube   protection and in that between the transport tube and the tube-   casing are formed channels for a coolant.