Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
  • C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B3/00—General features in the manufacture of pig-iron
  • C21B3/04—Recovery of by-products, e.g. slag
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B19/00—Obtaining zinc or zinc oxide
  • C22B19/28—Obtaining zinc or zinc oxide from muffle furnace residues
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/02—Working-up flue dust
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
  • F27B3/04—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces of multiple-hearth type; of multiple-chamber type; Combinations of hearth-type furnaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
  • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
  • F27B3/22—Arrangements of air or gas supply devices
  • F27B3/225—Oxygen blowing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D3/00—Charging; Discharging; Manipulation of charge
  • F27D3/14—Charging or discharging liquid or molten material
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies

Definitions

• the present invention relates to a process for treating powdery products or containing no recoverable substance, such as dried sludge from urban, rural or industrial wastewater settling tanks, asbestos particles or fibers to be packaged in a form inert, either containing recoverable substances such as leaching residues from hydrometallurgy, zinciferous dust from steel production (dust from an electric arc furnace or converter sludge, etc.) - H may also be ore concentrates or powdered products containing substances such as, for example, sulfides, arsenides, antimonides, stannates, sulfates, arsenates, metal antimoniates.
• EAFD Electro Arc Furnace Dust
• the machine-gun placed in the oven has been containing increasing amounts of galvanized steel, which has led to an increasing concentration of this dust in zinc, lead and cadmium oxides (ZnO, PbO, CdO).
• plastics and paints lead to contamination of the dust with chlorine and fluorine.
• the authorities responsible for environmental legislation decided to classify the product, imposing strict rules for its transport and its discharge (in the USA, it is classified under the number K061 by the Environment Protection EPA Act).
• the zinciferous dust to be treated is mixed, after having been pelletized or not, with a reducing agent, formed for example of coke or of coal. Then, this mixture is heated in a fossil or electric fuel furnace causing the reduction of ZnO, PbO, CdO into vapors which are reoxidized in another zone of the furnace. These oxides are recovered in the treatment of fumes.
• the oxide thus produced still contains too much chlorine and fluorine.
• treatments secondary rotary kiln or treatment with Na 2 C0 3 ) to lower these chlorinated and fluorinated contaminations. They are essential because the only current outlet for this oxide called “WAELZ” is to be mixed with other materials as the loading of "IMPERIAL SMELTING” ovens for which the requirements "chlorine” and “fluorine” (as well as Na 2 0 and K 2 0) are very severe.
• the known processes producing metallic zinc consist in reducing the oxides of zinc, lead and cadmium (but not the iron) and in recovering the vapors in a condenser.
• the ovens are electric plasma ovens (PLASMADUST or PLASMASCAN) or electrodes, like the "ELKEM MULTIPURPOSE FURNACE” oven heated by resistance in the slag.
• PLASMADUST or PLASMASCAN electric plasma ovens
• electrodes like the "ELKEM MULTIPURPOSE FURNACE” oven heated by resistance in the slag.
• the invention makes it possible to remedy the drawbacks of known methods and above all to simultaneously solve in a very simple, efficient and economically justified manner, the problems resulting from the use of a condenser and / or a separator for the recovery of certain reaction products and this not only in the reprocessing of dust from an electric arc furnace, but in all areas where it is necessary to introduce a pulverulent product into a liquid.
• this product is brought into contact with a liquid substance, not aqueous, heated by combustion gases and made up of at least 30% by volume of a material which is largely oxidized, substantially sheltered from the gaseous atmosphere which may contain these combustion gases, in a manner such as to avoid as much as possible the emission of dust which may come from this pulverulent product, this substance being maintained at a temperature which is such that it makes it possible to form with the slow pulverulent product a liquid phase at this temperature.
• an oxidizing agent is introduced into the abovementioned liquid separately from the slow product.
• the oxidizing agent is introduced in the form of an oxidizing gas into the liquid by means of a flame burner immersed in the latter, so as to thereby maintain at the same time this liquid at a temperature higher than its solidification temperature.
• this product is introduced, during a first step pulverulent and an oxidizing agent in a liquid slag in a non-reducing zone so as to form zinc oxide dissolved in this slag and, in a second step, this liquid slag is transferred to a reduction zone where a reducing agent is introduced therein to reduce zinc oxide into volatile metal zinc, this metal zinc as well as the gaseous substances formed during this stage being evacuated as they are formed, the oxidizing agent and the pulverulent product being introduced separately into the non-reducing zone, in particular into the liquid slag contained in this zone, in such a way as to avoid the formation of dust which could be entrained with the gaseous substances formed in this zone.
• the invention also relates to an installation for the treatment of a slow pulverulent product, in particular for the implementation of the method as described above.
• This installation comprises a heating chamber intended to contain, over a certain part of its height, a liquid into which the pulverulent material can be introduced, means being provided to allow, on the one hand, the separate evacuation of all gaseous substances formed from the pulverulent product and, on the other hand, the separate introduction into the above-mentioned liquid of an oxidizing agent and the pulverulent product, in such a way as to avoid as much as possible the formation of dusts which may be discharged with the above gaseous substances.
• Figure 1 is a schematic elevational view in section along line I-I of Figure 2 of a first embodiment of an installation according to one invention.
• Figure 2 is a section along line II-II of Figure 1.
• Figure 3 is a schematic view in elevation and in section, on a larger scale, of part of a variant of the first embodiment of the installation according to the invention.
• Figure 4 is an elevational view in section of part of a second embodiment of the installation according to the invention.
• Figure 5 is an elevational view in section of another part of an embodiment of the installation according to the invention can be combined with the previous embodiments.
• Figure 6 is a section along line VI-VI of Figure 5.
• Figure 7 is a plan view in section of a third embodiment of the installation 1 according to the invention.
• the method according to the invention for the treatment of a pulverulent product is characterized by the fact that this product is introduced into a non-aqueous liquid substance with the aim of forming with this substance a liquid phase under conditions non-reducing, in such a way that dust emissions are otherwise suppressed, at least made very low and non-harmful and that the gaseous emissions resulting from this operation are confined.
• one of the essential aims of the process according to the present invention is to maintain the atmosphere at the place where the pulverulent product is brought into contact with the nonaqueous liquid substance, being in the liquid state or in the liquid state. solid state, substantially free of dust coming from the slow pulverulent product, so as to be able to easily isolate any gases produced by said contact.
• a non-aqueous substance in the liquid state is used, the melting temperature of which is equal to or greater than that of the pulverulent material, so that the latter is also melted upon contact with the above substance.
• the pulverulent material is formed from dust from a steel arc furnace and the non-aqueous liquid substance is formed from iron and calcium silicate in proportions such as the melting temperature of the phase thus formed is greater than 1450 ° C.
• a nonaqueous liquid substance having in the pure state a melting point lower than that of the pulverulent material, but which reacts with this pulverulent material, so as to form a solution whose point of fusion is less than that of the nonaqueous liquid substance.
• the pulverulent material is formed from asbestos residues or sludge from settling tanks and the non-aqueous substance is also formed from calcium and iron silicates in proportions such as the melting point of the phase thus formed is less than 1300 ° C.
• the pulverulent product to be treated is introduced, substantially sheltered from the surrounding gaseous atmosphere, in a non-aqueous liquid having a solidification temperature above 800 ° C. and consisting of at least 30% by volume of a material which is largely oxidized, and this in such a way as to avoid as much as possible the emission of dust which may come from this pulverulent product when it is introduced into this liquid.
• FIGS 1 and 2 schematically represent an installation which may be suitable for this purpose.
• This installation comprises a chamber 1 which can contain a liquid 2, corresponding to the aforementioned liquid, and the upper part of which, above this liquid, is divided into two successive compartments 3 and 4 by a partition 5 whose lower edge 6 is immersed in the liquid 2.
• a supply pipe 7 passes through the first compartment 3 to terminate with its lower end just at the level of the liquid 2 or slightly above or below it, so as to allow the introduction of the product pulverulent slow to be treated directly in the liquid 2 and protected from the gaseous atmosphere of the compartment 4.
• a pulverulent zinciferous product is totally or partially oxidized, chlorinated, fluorinated and / or sulfurized.
• the pulverulent product contains chloru ⁇ res and / or fluorides, as a result of the temperature of the liquid 2, these can evaporate and form a gas phase in compartment 3, above the level of the liquid.
• these chlorides or fluorides in the gaseous state could be removed from compartment 3 and then be condensed.
• non-condensable gases are formed in compartment 3, they are evacuated via a pipe 11 '.
• a burner 10 with a flame immersed in the liquid 2 thus making it possible to introduce an oxidizing agent in the form of an oxidizing gas in the liquid and at the same time to maintain this liquid at a temperature higher than its solidification temperature.
• it may be a gas, liquid fuel or pulverulent solid fuel burner.
• FIG. 3 schematically shows a vertical section of a heat exchanger 12 mounted upstream of the supply pipe 7.
• This preheating can be such that, depending on the nature of the pulverulent product, it can help to melt or decompose the latter at least partially before introducing it into the liquid 2.
• it is a zinc, chlorinated and / or fluorinated pulverulent product
• such a decomposition could take place thus allowing the formation of chlorides and / or fluorides in the gaseous state which are then recovered in the condensed state above the exchanger 12, before the introduction of the powdery product into compartment 3.
• the liquid 2 is formed by a slag, that is to say a mixture consisting mainly of oxides and metal salts which is heated by the injection of gas from the burner 10 placed in such a way that a whole movement is imparted to the liquid slag, as already mentioned above.
• a slag that is to say a mixture consisting mainly of oxides and metal salts which is heated by the injection of gas from the burner 10 placed in such a way that a whole movement is imparted to the liquid slag, as already mentioned above.
• This movement is such that the burnt gases are only collected in the second compartment 4 while the pulverulent product to be treated is introduced into the first compartment 3.
• the movement thus printed with hot liquid slag is such that it is propelled towards the compartment 3 into which the pulverulent product is introduced and this in such a way that this pulverulent product is entrained by the slag to be dissolved therein.
• the slag can be based on oxides and can consist of silicates and / or aluminates.
• the pulverulent product is introduced at or near the level of the liquid slag 2 so as to prevent this product from coming into contact with the gas phase located above the slag in compartment 4.
• the atmosphere contains only gases and vapors possibly emitted by the pulverulent product during the process of dissolution in the slag. It is also possible to introduce into the first compartment 3, in a controlled manner, an adequate gas intended for example to entrain the gases and vapors emitted by the pulverulent product.
• the presence of dust leaving the pulverulent product to be treated is zero or in any case extremely low in the atmosphere above the liquid of the first compartment 3.
• the method according to the invention and the device for implementing this method can be used to treat powdery products of an extremely varied nature. More particularly, it may be dust from industrial processes containing recoverable constituents. Dust from an electric steel mill is a good example.
• the iron oxide contained in the liquid slag 2 is brought to the valence three (Fe 3 0 3 or Fe 3 0 4 ) in contact with the oxidizing gases coming from the burner 10.
• the iron oxide will take up the valence two by oxidizing for example the sulphide according to the reactions: 3Fe 2 0 3 + MeS ⁇ 6Fe0 + S0 2 + MeO and 3Fe 3 0 4 + MeS - ⁇ 9FeO + S0 2 + MeO.
• Me denotes a non-ferrous metal, such as zinc, copper, etc.
• the SO 2 and / or As 2 0 3 produced in the compartment 3 where the pulverulent product is injected is diluted only by the other gases emanating from the slow pulverulent product when it is dissolved in the slag.
• the gases in compartment 3 are therefore very rich in S0 2 and / or 1 'As 2 0 3 which can be considered to be condensed by cooling, followed by compression in the case of SO.
• the pulverulent product contains volatile chloru ⁇ res, these are evaporated in compartment 3, as already mentioned above, during the process by which this product is finally dissolved in the liquid slag.
• This compartment 3 can advantageously be provided with a cooled wall 8 having the geometric shape which is suitable for recovering these chlorides in the liquid state or in the solid state.
• These chlorides are separated and sent to a company specialized in their treatment. If the pulverulent product to be treated contains fluorides, these are generally less volatile than chlorides and are mainly dissolved in the slag. The volatile part accompanies the chlorides as indicated above.
• the chamber 1 of FIGS. 1 and 2 and described above is used to prepare an oxidized slag which must then be transferred to another part of the device forming a reduction reactor.
• Such a reactor is shown in FIG. 4 and is designated by reference 13.
• the process according to the invention therefore comprises an oxidation step followed by a reduction step.
• a zinc-containing pulverulent product is used, originating in particular from the production of steel from scrap metal
• the pulverulent product and an oxidizing agent are introduced during this first stage into the liquid slag 2 of the zone of oxidation so as to form dissolved zinc oxide in this slag and, in a second step, this liquid slag is transferred to a second reduction chamber or reactor 13 where a reducing agent, for example coke or carbon 14, is introduced to reduce zinc oxide to volatile metal zinc.
• a reducing agent for example coke or carbon 14
• FIG. 4 shows a layer of coke 14 floating above the liquid slag 2 coming from the chamber 1 as shown in FIGS. 1 and 2.
• This slag enters through an opening 15 formed in one of the side walls of the reactor 13, at a level lower than that of the liquid slag 2.
• gases from the chamber 1 also called the oxidation chamber
• the inlet opening 15 of the reactor 13 is connected to the second compartment 4 of the chamber 1 also at a location located below the level of the liquid slag 2 contained therein.
• the connection between this compartment 4 and the reduction reactor 13 preferably takes place by a pipe (not shown) inclined towards the latter.
• the slag 2 is maintained in the molten state in the reduction reactor 13 by electrical elements penetrating said slag, in particular by carbon electrodes 16.
• auxiliary burners 17 advantageously open out through one of the side walls directly into the slag. These burners 17 are preferably arranged in the side wall of the reactor 13 opposite to that having the inlet opening 15.
• the reduction of the slag takes place at the interface between the latter and the layer of coke 14 which floats on its surface. This interface reaction is accelerated by the convection movements created in the slag by the concentration of energy dissipated by the Joule effect in the vicinity of the electrodes.
• the coke layer 14 advantageously has a thickness of 0.3 to 1 m and preferably 0.5 m. As the upper surface of this coke layer is cooler than its interface with the slag, this coke layer can play a role in purifying condensable metallic vapors.
• the electrical energy to be supplied is low, since the slag enters the liquid state in the reactor 13.
• the electrical energy must therefore only be used to supply the calories required for the endothermic reduction reactions by carbon and to compensate for inevitable thermal losses.
• the starting of the reactor 13 can be easily carried out by one or more of the auxiliary burners 17. These are generally gas or liquid fuel burners mounted in one of the side walls of the reactor, at a level such that the combustion gases emerge in the liquid slag. It may be advantageous to take advantage of this geometrical arrangement to accelerate the reduction reactions at the slag / coke interface thanks to the overall movement of the slag created in the reactor 13 by the injection of gas into the latter. It goes without saying that the coke is introduced into the reactor 13 by means of airlock 19.
• the temperature of the slag in the reactor 13 can be easily adjusted to different values.
• a temperature such as the reduction of iron oxide will be chosen up to 'in the metallic state is slow.
• nickel, chromium, cobalt, etc. it may be advantageous to cause a more intense reduction of the iron oxides, so as to dissolve these metals in an alloy with melting point. relatively low.
• the reactor 13 is provided with suitable tap holes 18 for removing, on the one hand, the spent liquid slag and, on the other hand, the possible liquid metallic phase.
• the gases produced by the reduction are conducted in a leaktight manner through pipes 22 to a condenser 20, preferably a plate condenser vertical 21, cooled under conditions such that the metals are recovered in the liquid state.
• a condenser 20 has been shown in FIGS. 5 and 6.
• the vertical plates 21 are arranged so as to create changes of direction of the gases.
• the reference 22 shows in one of the side walls of the condenser 20 the inlet opening for the gases coming from the reactor 13 via the pipes 22.
• the opposite wall of the condenser 20 has an outlet opening 23 for the gases applied ⁇ seen in metallic elements.
• Condensed liquid metal has been shown by the reference 24, while the arrows 25 indicate the direction of circulation of cooling air.
• Figure 7 relates to a third embodiment of the installation according to the invention.
• This installation is characterized by the fact that the oxidation chamber 1, the reduction reactor 13 and the condenser 20 are coupled so as to obtain only one very compact device.
• the compartment 4 is connected by a separate opening 15 to the reactor 13.
• the treated dust contains 20% zinc, 3% lead, 0.1% cadmium and about 1.5% chlorine, the rest being oxides including 30% FeO and 10% CaO.
• Silica (Si0 2 ) is added to the dust at the rate of 186 kg per tonne of dust.
• the oxidizing melting chamber 1 is heated by means of natural gas burners 10 with a flow rate of 83.3 Nm 3 CH 4 per tonne of dust.
• the dust and its additions are injected at a rate of 5.83 T / h.
• the power of the burners 10 is of the order of 5 MW.
• the chlorine in the feed is recovered in the fumes from chamber 1 in the form of ZnCl 2 at the rate of 46 kg / t of dust. 1.140 kg of slag are collected per tonne of dust which is transferred liquid to the reduction reactor 13.
• the reduction reactor 13 is heated by resistance in the slag 2 using graphite electrodes 16.
• the installed power is 2.2 MW.
• Coke 14 is added at the rate of 47.5 kg of coke per tonne of dust.
• the gases from reactor 13 contain CO and the vapors of zinc, lead and cadmium.
• a liquid alloy is recovered containing, per ton of treated dust, 205 kg of zinc, 34 kg of lead and 0.9 kg of cadmium.
• the spent slag is poured at the rate of 854 kg per tonne of dust.
• tap holes for several slightly oxidizable metallic liquid phase.
• a tap hole for each slightly oxidizable metallic liquid phase for example for copper, lead or also for a sulfurized liquid phase, for example copper mat Cu 2 S-FeS, nickel mat NiS-FeS, mixed mattes containing other sulphides, such as PbS, CoS, ZnS, etc.
• a tap hole could be provided for a liquid phase containing arsenic. If several liquid phases are to be separated, it seems desirable to provide in the reduction reactor 13 a pre-crucible (not shown), allowing the separation tion of these phases as it is good practice to do in non-ferrous metal metallurgy.

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• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
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• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Manufacture And Refinement Of Metals (AREA)

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• 1996
  • 1996-01-29 BE BE9600078A patent/BE1009996A3/fr not_active IP Right Cessation
• 1997
  • 1997-01-29 WO PCT/BE1997/000012 patent/WO1997028287A1/fr not_active Application Discontinuation
  • 1997-01-29 EP EP97901483A patent/EP0877827A1/de not_active Withdrawn
  • 1997-01-29 AU AU15373/97A patent/AU1537397A/en not_active Abandoned

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