FR2652013A1 - PROCESS FOR REMOVING DUST FROM FILTERS. - Google Patents

Abstract

It consists of blowing the filter dust in adjustable amounts into a slag tank and adjusting the depth of penetration, as well as the angle of the blowing lance, depending on the reaction of the slag. Metallurgical industry.

Description

The invention relates to a method for removing dust from

  filters by blowing these dusts into final liquid process slags, which are formed during the manufacture of cast irons, steels or other

foundry fumes.

  The filter dusts that occur in the metallurgical industry are pelletized in order to be able to

  be stored in landfills without releasing dust.

  This is a modus operandi that is not only very

  expensive, but which does not sufficiently secure

  luble in the water the eluates from the dust of filters,

  so that the smallest quantities of eluates in the

  filters are harmful to the environment.

  In contrast, eluates that are incorporated into process slags are less soluble in water. If we consider, for this purpose, that the insufflation of filter dust transforms soluble chromates in water into

  chromium compounds less soluble in water in lakes

  process third, filter dust blowing

  in process slags appears as special-

promising.

  In a general way, the insufflation of

  of filters in slags is a metal-

  which improves the final slags of

  cess. It is even a metallurgical operation that

  directly, and more often than not

  the metallurgical procedure in the manufacture of

  curing cast iron, steel or other foundry products, if the blowing of filter dusts does not take place in the final slags of the process, but during the manufacture of cast iron, steel or other foundry products. It should be noted that, if the blowing of the filter dust takes place in the said manufacturing process, then we are in the presence of a global metallurgical process which is different from the blowing into final slags.

  process, because the filter dust thus

  sufflées act up to said products of manufacture. he

  This is a risk that no steelmaker thinks of running.

  If, on the other hand, the insufflation of

  after completion of said manufacturing process

  For example, for the manufacture of steel, final process slags are available separately after being emptied from the steelmaking furnace. We can thus, while blowing dust of filters in

  process slags, do not affect the quality of

  steel, but simply on the final slag of steel.

  cessus which, as mentioned, is thus improved. This insufficiency

  filter dust becomes a process

  which differs from the direct insufflation of pus-

  filters in usual process slags.

  Dust blowing of filters which is included directly in a steelmaking process

  is described in Fachberichte HUttenpraxis Metallweiterverar-

  beitung, Vol. 20, No. 10, 1982: Verwertung von Filterstauben und Schlimmen aus der Abgasreinigung in Huittenwerken, p. 756, point 3.6. It interrupts a manufacturing process of

  steel, in this case by converter, during the course of

  manufacturing process, in order to be able to add to the contents of the steel converter, namely molten steel and slags

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  of the filter dust process. After adding the filter dust, the manufacturing process is resumed

  of interrupted steel, by what is called a post-in-

  sufflation. Molten steel, process slag and filter dust are thus swirled, which has the following disadvantages: the molten steel which, before the post-insufflation was relatively free of impurities,

  is then put in contact with the multiple impurities

  Finite filter dust, which can be absorbed by the process slag, but also by molten steel. Another disadvantage is that the interruption of

  normal process of insufflation in a manufacturing process

  conversion of steel to converter not only hinders

  operations, but comes at a considerable cost.

  saddle. Another process, described in the patent of the Republic

  Federal Republic of Germany No 35 05 982, differs from the

  described by the fact that it does not require additional treatment of filter dust to be blown into

  processes, in the manufacturing processes

  above-for example in the process of manufacturing steel to the converter. It is not incorporated in such a manufacturing process, which constitutes a difference

important.

  Trials and applications of this method

  have shown that filter dusts react

  very different and thus create considerable difficulties

  rable. It turned out that the place of insufflation must be selected correctly and that, in addition, certain

  devices for this procedure to be carried out without

  ficulty. Conditions that allow for insufflation

  on an industrial scale of filter dust in

final process slags.

  The essential disadvantages of this procedure

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  are: a) Very different exothermic reactions, when

  insufflation of filter dust in

  final process thirds which, if no regulation mechanisms are provided, result in the formation of spontaneous foam in the final process slags,

  so that the milk tanks in which

  the final process slags are partially emptied

  because of this foam. This causes great difficulties if the insufflation of the dusts of

  filters is carried out in the foundry.

  (b) The formation of foam in the final slags of

  cures so much heat that the insufflation device can hardly be sufficiently protected and that the insufflation process can not be sufficiently observed, which

  question this mode of operation in basic workshops.

series.

  The invention therefore aims at a method which allows a

  industrial-scale sufflation of filter dusts

  in process final dairies.

  The process according to the invention is characterized in that it consists in blowing the filter dust into a slag tank containing a final slag.

  process, or in a comparable device for

  liquid, by means of an insufflation lance outside the production workshops, the filter dust being blown in adjustable quantities and the depth of penetration and the angular position of the insufflation lance being adapted to the final milk of the process.

  According to an improvement of the invention, the

  assigned is to provide a protection device vis-à-vis the heat and observation, in the immediate vicinity of the

slag tank.

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  Another improvement of the invention consists, in the case of filter dust containing no zinc, to add them, before the insufflation, substances

fine providing heat.

  According to the invention it is intended to use, as fine substances providing heat, dusts of

filters containing zinc.

  It is also part of the invention to blow filter dust directly into devices

  evacuation of blast furnace slag.

  It is possible to control the formation of foam in slags by the fact that the process of insufflation of filter dust automatically makes it possible to adjust, by a remote control, the quantities of filter dust to be blown at any moment, while allowing displacement and a stop of the lance of insufflation of filter dusts in continuous and very fast. Advantageously, it is possible to provide a protection device with respect to heat

  and observation in the immediate vicinity of the slag tank.

  Thanks to these provisions, which are provided for in

  in various procedures but not used in any filter dust blowing process

  in process liquid final slags, it is possible to obtain

  induce flawless, industrial-scale insufflation of filter dusts in process liquid end slags.

  This new process allows, in a more eco

  hitherto, to safely dispose of all filter dusts, with the exception of

  dust with a high zinc and lead content.

  For the practical implementation of the process described, it may be thought that, during the insufflation of filter dust, it may occur, under certain circumstances,

  difficulties if the surface of the slag tank is

  chills relatively quickly and if we can no longer detach

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  expensive slag crust thick and very cold, when blowing filter dust. In such a case, it can be seen that the amount of dust

  Filters that can be insufflated should be smaller.

  It will be mentioned, in this respect, that when using the process according to the patent of the Federal Republic of Germany No. 39 06 868, excessive heat can be produced if the final slags of the process, filter dusts containing

  zinc. It follows a great expense in cooling elements

  the condensed superheated product and for the ef-

  gaseous fluids from slag tanks going to dust collection plants. But long cooling paths are generally troublesome, especially because of

clutter.

  Thus, the process mentioned above can be further improved so that filter dust can also be blown into slag tanks or comparable liquid slag devices, while some cooling has already occurred. We can

  also maintain the release of heat within acceptable limits.

  ceptables, during the insufflation of filter dust.

  This improvement is obtained according to the invention, in that in the case of filter dust containing no zinc, it is added before

  insufflation of the fine substances providing

  their. According to the invention, it is intended to use as fine substances providing heat

filters containing zinc.

  It is also part of the invention to blow filter dust directly into devices

  evacuation of blast furnace slag.

  When using the improved process

  tioned, a tank of slags or a

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  comparable for liquid slag, which is not deter-

  from the point of view of solidification on the surface of the slag. It also prevents too much clearance from

  heat when blowing filter dust.

  According to the invention, it is possible to add

  before insufflation, in the slag tank or in a

  positive comparable to zinc-free filter dust, filter dust containing up to 50% of zinc, in order to dispose of this way of fine substances

  providing heat to overcome the disadvantages

  tioned. If a sufficient quantity of filter dust containing zinc is not available for this purpose, it is possible to add other sources of heat-producing fine substances, such as, for example, dusts having thin and active aluminum parts or other sources of

  fine substances that have an exothermic action.

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Claims (5)

  A method of disposing of filter dusts by blowing these dusts into final process liquid slags which are formed in the manufacture of cast irons, steels or other foundry products, characterized in that it consists in blowing the dust of the filters in a slag tank containing a final process slag, or in a comparable device for liquid slag, by means of an insufflation lance outside the manufacturing plants. , the dust of the filters being insufflated in adjustable quantities and the penetration depth and the angular position of the insufflation lance being adapted to the final slag of the process. 2. Method according to claim 1, characterized in that it consists in providing a protective device   vis-à-vis the heat and observation, in close proximity diate of the slag tank.   3. A process according to claim 1 or 2,   terized in that it consists, in the case of filter dust containing no zinc, to add them before   insufflation of the fine substances providing   their. 4. Process according to claim 3, characterized in that it consists in using, as fine substances 9 2652013   supplying heat, filter dust zinc.   5. A process according to claim 1, 3 or 4,   characterized in that it consists in blowing the dust from the filters directly into the water evacuation devices. thirds of blast furnaces.