Classifications

• • 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
  • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B13/00—Making spongy iron or liquid steel, by direct processes
  • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
  • C21B13/105—Rotary hearth-type furnaces
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B13/00—Making spongy iron or liquid steel, by direct processes
  • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
• • 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
• • 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
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen
• • 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

Definitions

• the present invention relates to a method for the thermal treatment of residues containing heavy metals, e.g. Sludges from surface treatment, pickling and cleaning, metalization and tinning processes of metal parts.
• residues containing heavy metals e.g. Sludges from surface treatment, pickling and cleaning, metalization and tinning processes of metal parts.
• the object of the present invention is therefore to propose a method for the thermal treatment of such heavy metal-containing residues.
• a method for the thermal treatment of residues containing heavy metals in a multi-level furnace which is divided into three zones, each zone having a plurality of superimposed levels and the method comprising the following steps: • Continuous introduction of the heavy metal-containing residues on the top floor of the first zone of the deck oven, the residues being gradually transferred to the second zone and drying while, • Continuous introduction of reducing agents and desulfurization agents onto the top floor of the second zone, the Reducing agent and the desulfurizing agent are mixed with the dried residues, the mixture is heated to approximately 800 ° C. and calcined and gradually transferred to the third zone, • heating the mixture to approximately 1000 ° C. in the third zone, reducing the metals the exhaust gases that arise in this third zone are extracted and treated separately,
• a major advantage of the invention is that it is possible to reduce and separate the metal oxides, sulfates, chlorides, etc. present as a mixture (in particular iron and zinc), so that the separated fractions are input materials for other processes. In this way, valuable materials can be produced from essential components of the residual materials. After the process has been completed, the iron content can be returned to the production process of a steel mill. Heavy metal oxides are concentrated to such an extent that they can be used as raw materials for the extraction of heavy metals. What remains are ashes, which essentially consist of inert substances such as S.C> 2, Al2O3, MgO, ... and an excess of reducing agents.
• the heavy metal-containing residues are heated indirectly by heating resistors or directly by burners to approximately 200 ° C., so that the water is completely evaporated and then transferred to the second zone.
• reducing agent and desulfurizing agent are mixed with the heavy metal-containing residues and this mixture is heated up to approximately 800 ° C., during which the mixture is calcined.
• the carbonates and sulfates contained in the mixture are decomposed and converted to metal oxides, releasing carbonic acid and sulfur dioxide become.
• the sulfur dioxide reacts with the desulfurization agents so that the sulfur content in the gases inside the deck furnace remains low.
• the calcination is complete and the mixture is introduced into the third zone and further heated.
• the metal oxides begin to react with the reducing agents, whereby the heavy metals evaporate and are discharged together with the exhaust gases from the deck oven.
• the heavy metals are extracted on the floors in the third zone where they are formed and treated separately from the other exhaust gases. These exhaust gases are then e.g. oxidized in an afterburning chamber, the heavy metals being converted to heavy metal oxides which can then be separated from the exhaust gases in a filter device.
• the iron oxides remaining in the deck furnace are reduced to metallic iron.
• the metallic iron produced in this way is removed from the furnace together with the residues of the material introduced, the ashes of the reducing agents and any excess reducing agents that may be present.
• sludge-like, heavy metal-containing residues can be fed in, whereby caking of the particles is avoided by a targeted process control and by constant circulation.
• the process delivers a fine-grained end product. This is of particular advantage when ash-forming reducing agents are used. Since the solid end product is fine-grained, it is easy to separate the ash from the iron. This separation can e.g. B. in the hot state via classification.
• the quality of the directly reduced iron obtained in this way is almost independent of the amount of residues of the reducing agent.
• the iron obtained can then be processed into briquettes or placed directly in a melting furnace (electric furnace, etc.) and processed further.
• the resulting residues can be recycled with the unused reducing agents that may be contained in them in a separate gasification reactor, the ash-forming constituents advantageously being separated out as liquid slag and the raw gas formed in the deck oven used as combustion or reducing gas.
• the charging of reducing agents can also be divided into several stages. There is the possibility that coarse-grained reducing agents (1-3 mm) are introduced further up in the second zone of the deck oven and fine-grained reducing agents ( ⁇ 1 mm) are added below. This largely avoids the discharge of dust with the exhaust gases and accelerates the course of the reaction through the fine reducing agent particles introduced below.
• the heavy metal-containing residues can, however, also be mixed with - at least some of the required - reducing agents or desulfurizing agents before they are introduced into the deck oven. This is particularly true in the case of treating sludges with a high water content which are mixed with at least some of the reducing agents or desulfurizing agents required before they are introduced into the furnace. This is because the sludge usually has a sticky consistency and, when mixed with a reducing agent or desulfurizing agent, is easier to put in the oven. Mixing with the reducing agents or desulfurizing agents prevents the input material from forming agglomerates when heated.
• the heavy metal residues are continuously circulated by rakes attached to each floor of the furnace and gradually transported to the floor below.
• the constant agitation prevents the particles from caking together.
• the rate of circulation depends on many factors such as. B. the geometry of the rake, the thickness of the layers, etc.
• the heavy metal residues, any reducing agents and desulfurizing agents on the floors should be circulated at least once every one to three minutes, which largely prevents agglomeration.
• oxygen-containing gases that have a temperature of at least 250 ° C.
• a gaseous reducing agent can also be blown in on the bottom floors of the third zone of the deck oven.
• one or more floors in the furnace, which are below the floor to which reducing agents are introduced are heated by means of a burner.
• gases are drawn off from the deck oven on each zone on one or more floors.
• These hot gases can then either be passed through a CO 2 scrubber to reduce the amount of gas and increase the reduction potential of the gas, or can be passed through an additional reactor in which carbon is present, so that the carbon dioxide contained in the hot gases reacts with the carbon to form carbon monoxide according to the Boudoir equilibrium and thereby the reduction potential of the gas is increased.
• the gases enriched with carbon monoxide are then returned to the deck oven.
• the Schwerme ⁇ metals can then be sucked off in a relatively small gas quantity on these floors through an outlet in the side wall of the oven.
• the extracted gas mixture is afterburned, cooled in a cooling device and then cleaned with the aid of a filter before it is released.
• the deck oven can be operated under a certain excess pressure. In contrast to a rotary kiln, which is sealed over water cups with a diameter of approximately 50 m, this is very easy to achieve in a deck oven that only has small seals on the drive shaft. In such a case, pressure locks must be provided for the input and export of material.
• Fig. 1 a section through a deck oven for the thermal treatment of residues containing heavy metals.
• 1 shows a section through a deck oven 10, which consists of three zones 12, 14, 16 lying one below the other, each of which has a plurality of floors 18.
• These self-supporting levels 18, as well as the jacket 20, the cover 22 and the bottom 24 of the furnace are made of refractory material.
• each zone 12, 14, 16 there is a suction nozzle 26, 28, 30 through which the gases can be evacuated from the furnace 10.
• the agbase of the three zones 12, 14, 16 have a different composition so that it makes sense to treat the exhaust gases of the different zones 12, 14, 16 separately.
• the rakes are designed so that they roll the material inside out on one floor and then outside in on the floor below, so that the material is transported through the furnace from top to bottom.
• the shaft 34 and the rakes are air-cooled and openings are provided on the rakes through which air can flow into the interior of the furnace and can be used there for afterburning.
• the residues are applied to the first floor of the first zone 12, while the reducing agents and the desulfurizing agents are fed into the second zone 14 and are brought into contact with the residues containing heavy metals.
• the heavy metal-containing residues are heated to approximately 200 ° C. and dried.
• the reducing agents and the desulfurizing agents can be introduced into the furnace.
• These reducing agents can be in gaseous form or in liquid or solid form.
• the reducing agents are carbon monoxide, hydrogen, natural gas, petroleum and petroleum derivatives, or solid carbon carriers, such as lignite coke, petroleum coke, blast furnace dust, coal, or the like.
• the desulfurizing agents contain, for example, lime (CaO), limestone (CaC0 3 ) and / or magnesite (MgO).
• the reducing agents and the desulfurizing agents which are introduced into the second zone 14 are mixed there by the rakes with the heated, heavy metal-containing residues and heated to approximately 800.degree.
• the mixture of heavy metal-containing residues, reducing agents and desulfurizing agents is heated to approximately 1000 ° C. Due to the high temperature and the presence of carbon mono- oxide, the oxides contained in the residues are gradually reduced to metal during transport through the deck furnace 10.
• nozzles 38 are provided for blowing in hot (350 ° C. to 500 ° C.) oxygen-containing gases, through which air or another gas containing oxygen can be introduced into the deck oven 10. Due to the high temperatures and the presence of oxygen, part of the carbon burns to carbon dioxide, which in turn reacts with the excess carbon and is converted to carbon monoxide. The carbon monoxide finally reduces the oxides.
• burners 40 which ensure a constant high temperature in the levels of the furnace.
• Gas or coal dust burners can be used here. These burners 40 can be fired with air for preheating and / or for additional heating with gas or coal dust.
• An additional reducing gas can be generated through the quantitative ratio between oxygen and fuel, or afterburning of the process gases is achieved with excess air.
• an excess of carbon monoxide can be generated in the burner.
• With external combustion chambers it can be avoided that the ashes of the burned coal get into the furnace and mix with the iron.
• the temperatures in the combustion chambers are chosen so that the slag can be drawn off in liquid form and can be disposed of in a glazed form.
• the production of carbon monoxide reduces the consumption of solid carbon carriers in the furnace 10 and thus also the ash content in the finished product.
• a gaseous reducing agent for example carbon monoxide or hydrogen
• the addition of a gaseous reducing agent, for example carbon monoxide or hydrogen, through special nozzles is provided on the last or the last two floors.
• the reduction of the metal oxides can be completed in this atmosphere with an increased reduction potential.

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

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• 1998
  • 1998-11-05 LU LU90315A patent/LU90315B1/de active
• 1999
  • 1999-03-02 TW TW88103150A patent/TW424004B/zh not_active IP Right Cessation
  • 1999-11-04 AU AU15512/00A patent/AU750943B2/en not_active Ceased
  • 1999-11-04 WO PCT/EP1999/008439 patent/WO2000028094A1/de active IP Right Grant
  • 1999-11-04 TR TR200101253T patent/TR200101253T2/xx unknown
  • 1999-11-04 SK SK596-2001A patent/SK5962001A3/sk unknown
  • 1999-11-04 CN CN99812281A patent/CN1323359A/zh active Pending
  • 1999-11-04 BR BR9915309A patent/BR9915309A/pt active Search and Examination
  • 1999-11-04 PL PL34823099A patent/PL348230A1/xx unknown
  • 1999-11-04 US US09/807,998 patent/US6383252B1/en not_active Expired - Fee Related
  • 1999-11-04 JP JP2000581260A patent/JP2002529597A/ja active Pending
  • 1999-11-04 EP EP99957993A patent/EP1137818A1/de not_active Withdrawn
  • 1999-11-04 CA CA 2345412 patent/CA2345412A1/en not_active Abandoned
  • 1999-11-04 KR KR1020017004421A patent/KR20010080042A/ko not_active Application Discontinuation
  • 1999-11-04 CZ CZ20011548A patent/CZ20011548A3/cs unknown
• 2001
  • 2001-03-30 ZA ZA200102662A patent/ZA200102662B/en unknown

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