JP2002509194A - Sustainable steelmaking process by effective direct reduction of iron oxide and solid waste - Google Patents

Abstract

(57) [Abstract] A method of treating iron oxide to produce an iron product is to treat a composite pellet formed of iron oxide and a solid carbonaceous reducing agent in a pre-reduction furnace (20) to reduce the degree of reduction to 75%. % Or more of the direct reduced iron product. The directly reduced iron product is conveyed to a smelter furnace (30) at a temperature in the range of 700 ° C. to 1400 ° C., and the directly reduced iron product is melted in the smelter furnace (30) with added oxygen or an oxygen / air mixture. To form an iron melt containing carbon, slag and a top gas containing carbon monoxide. Heat to the pre-reduction furnace is provided at least in part by combustion of the top gas from the smelter furnace (30) using air or oxygen. Also disclosed is an integrated device (10) for performing the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD OF THE INVENTION The present invention relates generally to the production of iron and steel, and more particularly to the production of iron oxide (DRI) which produces iron products such as steel, semi-steel or pig iron in a manner that is favorable from an environmental point of view. It relates to a method in which direct reduction is introduced. More favorable environmental performance preferably includes minimizing the consumption of energy and greenhouse gas emissions and maximizing the reliability of by-product production.

BACKGROUND OF THE INVENTION Various methods have been proposed for pre-reducing and treating raw materials or pre-prepared forms of iron ore to produce sponge iron or pig iron so as to be melted in a furnace, particularly in an electric arc furnace. Are coming. One example is the Midrex DRI method developed by Midrex Corporation, which recycles to produce direct reduced iron used as a direct feed to various melting furnaces, including blast furnaces and electric arc furnaces. Natural gas is used to directly reduce iron ore concentrate pellets. A similar pellet-based method is Hyl III. In another method, fine iron ore concentrate is pre-reduced in a fluidized bed or a circulating fluidized bed. In both types of processes, the product can be transported directly to the melting furnace or hot briquetted to allow transport and storage without oxidation and self-heating.

[0003] F developed by Midrex and described in, for example, International Metallurgical Plant Technical Journal, February 1991, p. 36 and Steel Times, December 1994, p.
The asmet ™ method is the DRI method, the product of which has been proposed as a direct feed to various melting furnaces, including blast furnaces and electric arc furnaces. In that process, composite green pellets, pulverized coal or similar solid reductant and binder formed from iron ore concentrate are passed through a hearth furnace as a single pellet depth layer. The degree of metallization of the product (expressed as a percentage of total iron converted to metallic iron) can be varied to suit the end use purpose. The product is (hot briquette iron-HBI
To obtain hot DRI) or conveyed as hot DRI directed to an adjacent iron or steelmaking furnace. The references mentioned above refer to this furnace as a blast furnace, an electric arc furnace (EA).
F), submerged arc furnace (SAF), or energy optimization furnace (EOF)
Suggests that you can do it.

In the Inmetco ™ process developed by International Metal Reclamation Company, coal and finely divided stainless steel crusher waste are processed into green pellets, which are converted in a rotary hearth furnace. Pre-reduction processing is performed. The products of this furnace are discharged as hot DRI pellets into the arc furnace via a transfer bin. This method has many similarities to the Fastmet method.

[0005] The SL / RN ™ process developed by Lurgi revolves iron ore fines and pulverized coal directly without pellets for the purpose of producing DRI products that are again transferred to the range of the smelter. Feeding to the kiln furnace.

[0006] A modification that further specializes in the SL / RN method is the Weertz kiln. This method is used for the purpose of reprocessing high zinc content iron rust dusts, especially such dusts generated from electric furnaces using scrap from galvanized steel products. The dust in this case is discharged to the kiln as a composite green / pellet. During the heating operation up to 1000 ° C. to 1250 ° C., the zinc content is volatilized, then captured as zinc oxide and subsequently reprocessed to produce zinc metal or agglomerated zinc dust. The iron content of this iron rust dust is converted to either high iron slag or DRI, which is further recycled to form a liquid iron product using a wide range of treatment furnaces, including blast furnaces and BOF. So that it can be melted.

[0007] Other specialized modifications of the SL / RN method were developed by Lurgi and Mannesman Demarg and are also described in the October 1986 SEIASI Shunkan page 29. This is a Combismelt method as described above. This method uses a Sl / RN kiln to generate pellets or fine DRI that are melted in a submerged arc furnace. The submerged arc furnace can be supplied with high or low temperature DRI with a reduction of 80 to 90% (percentage of removing oxygen from iron oxide present in iron ore). This equates to 70-80% metallization. In case of high temperature DRI filling method, DRI
Is transferred to the submerged arc furnace by a skip or hopper.

[0008] The Hismelt ™ process uses coal as the primary energy source and reducing agent. The method includes an integrated combination of a melting vessel and a pre-reduction tower or a circulating fluidized bed configuration, wherein the top gas from the melting vessel is fed to the descending steel charge in the pre-reduction unit. To rise. This arrangement results in a relatively low pre-reduction of the iron ore from the pre-reduction unit, such as a reduction value on the order of about 30%, which results in the melting device having to operate with a high energy input. This can be achieved in dissolving equipment that requires a high volume of injected air and a high vortex environment (
Requiring high afterburning (expressed as a percentage of carbon monoxide to be burned to carbon dioxide). At the required temperatures in the gas space of the vessel and the melting vessel, significant difficulties can arise with the refractory degradation, so that slugs can be compared to blast furnaces or melting furnaces that use a high degree of pre-reduction. Therefore, it becomes relatively low in FeO.
High levels of FeO in the slag prevent direct processing by polishing the high volume of slag generated to replace the cement and reduce both economic and environmental reliability from slag by-products Let it.

[0009] In general, it was 1970 to develop a steelmaking process that requires less capital investment than traditional integrated steelmaking processes, reduces coke requirements and allows for the direct use of fine iron ore. There has been considerable interest since the 1970s. More recently, steel as a product has been perceived as environmentally undesirable in the last quarter century due to its high energy consumption and greenhouse gas emissions resulting from its production compared to competing materials such as wood or concrete. Steel industry is increasingly aware that

[0010] The most successful low investment capital cost treatment methods in steel production are currently based on electric furnaces. These processes are known as steel mills or mini-mills, which are supplied with scrap iron and increasing the supply of DRI and HBI from DRI plants. The EAF mini-mill plant contains a high degree of electricity, scrap and highly reduced DRI or HBI (typically with 90-95% reduction or 87-94% metallization). It has the disadvantage of requiring feedstock. DRI and HBI plants, on the contrary, require a significant amount of low-cost natural gas, a high-grade energy source compared to coal. If the arc furnace uses a high percentage of scrap, the steel product should contain high levels of harmful residual elements such as copper, arsenic and tin that enter the steel product and adversely affect the mechanical properties of the steel become. Controlling this contamination requires dilution of the scrap by using a sufficient amount of DRI or HBI from the steel ore. However, the production of DRI and HBI requires capital investment and has little effect on improving the overall energy consumption and greenhouse gas emissions in steel production. Other disadvantages of EAF processing methods that use high levels of DRI and HBI are cement (ie cement clinker replacement) due to high FeO content (typically> 10%) and the presence of free or undissolved flux )
Is to produce a large volume of slag which is not entirely suitable for a direct processing method with a polishing action to produce slag. These slags are typically used for road aggregates that are substantially less economical and have less environmental benefits.

SUMMARY OF THE INVENTION The present invention encompasses two important technical ideas by addressing these issues to processing using self-reducing pellets, such as composite pellets of coal and iron ore. The first concept relates to the interaction between the pre-reduction stage and the smelting stage, producing a relatively high rate of high temperature feed to the smelting furnace while at least partially from enthalpy and from the smelting furnace. Enhance integration at these stages by performing pre-reduction in plants such as rotary kilns, moving hearths, rotating hearths or moving grid furnaces to obtain heat for the pre-reduction stages from gas combustion Has been proposed. As a second technical idea, attention is paid to the slag component of the smelting furnace product, but this slag is used as a high-value material that can be substantially replaced by Portland cement or similar cement for concrete production during polishing. It has been proposed to provide

In another aspect, the preferred embodiment of the present invention ignores the traditional treatment concept of melting furnace slag and off-gas and instead produces useful slag and utilizes off-gas directly, and its preferred The aim is to be itself sufficient in terms of electrical and / or mechanical energy. It also ignores the traditional purpose of requiring a high degree of afterburning in smelter furnaces.

In another aspect, a preferred embodiment of the present invention eliminates the need for coke or low-distribution coal and reduces the use of reducing agents produced from renewable fuels such as wood, timber waste or coal from greenhouse waste. Makes use possible.

In another aspect, a preferred embodiment of the present invention eliminates the need for a flux kiln and allows for the combustion of the raw flux in the pre-reduction stage.

[0015] In a first aspect, the present invention is a method of treating iron oxide to an iron product, comprising a composite pellet (preferably charcoal if possible) formed of iron oxide and a solid carbonaceous reducing agent. ) In a pre-reduction furnace to reduce the degree of reduction to 75% or more (> 65% of the degree of metallization)
To form a directly reduced iron product, and direct reduced iron product to 700 ° C to 1400 ° C (preferably 800 ° C to 110 ° C).
0 ° C) to a smelter furnace at a temperature in the range of 0 ° C, where the direct reduced iron product is melted in the smelter furnace with added oxygen or an oxygen / air mixture to remove the top gas containing carbon, slag and carbon monoxide. Forming an iron melt comprising recovering molten iron from the smelter furnace, wherein heat to the pre-reduction furnace is provided at least in part by combustion of said top gas from the smelter furnace using air or oxygen. A method is provided for including.

Preferably, the gas composition in the pre-reduction furnace minimizes or avoids excessive re-oxidation of the reduced pellets.

Preferably, the off-gas from the pre-reduction furnace is recovered in a means for generating energy from the off-gas, preferably in a waste heat boiler or gas turbine.

[0018] Preferably, one or more flux raw materials are also conveyed to a pre-reduction furnace prepared for internal melting, and then passed at an elevated temperature to a smelter furnace. In one embodiment,
The slag flux contains the raw lime and / or dolomite, the adjustment of which includes calcining the lime and / or dolomite. In other cases, the flux includes a combustion flux that is regulated by pre-heating at another plant.

The degree of reduction of the intermediate DRI product is preferably (equal to 73-86% degree of metallization)
It is in the range of 80-90%. By maximizing the degree of pre-reduction, the post-combustion energy requirements in the smelter furnace are significantly reduced, thus making the melting process less vulnerable to refractories, lower critical conditions, less eddies and less erosion. ,as a result,
When the smelter furnace is an oxygen-blown EAF, there is a relatively low level of oxygen or air consumption or a relatively low level of electricity consumption compared to prior art treatment methods such as DIOS or Hismelt. In addition, the amount of energy in the top gas (which does not need to be as high as to supply heat to the post-combustion smelter furnace) is used for combustion to supply heat to the pre-reduction furnace and the waste heat boiler or gas turbine It is possible.

The present invention is also an integrated apparatus for treating iron oxide to produce an iron product, comprising treating a composite pellet formed of iron oxide and a solid carbonaceous reducing agent to reduce the degree of reduction to (
A pre-reduction furnace that forms a directly reduced iron product above 75% (equivalent to a degree of metallization of> 65%) with pellets containing residual carbon; and transports the melter and oxygen or oxygen / air mixture to the melter. A smelter furnace equipped with a means, and means for directly transferring the reduced iron product at a temperature in the range of 700 ° C to 1400 ° C, preferably 800 ° C to 1100 ° C, from the pre-reducing furnace to the melting chamber, wherein the melting furnace is Operable to melt the directly reduced iron product with added oxygen, optionally electrical energy, in the melting chamber, wherein the ratio of carbon monoxide to carbon dioxide is greater than 1.0 by volume Means for forming an iron melt containing carbon, slag and top gas, means for recovering molten iron from the melter, and refining by supplying heat to the pre-reduction furnace at least in part from enthalpy. Means for effecting the combustion of said top gas from the furnace.

Preferably, the combustion of the top gas takes place inside a rotary kiln or, in the case of a rotary hearth furnace, a pre-reduction furnace and is spaced around the furnace, for example along a rotary kiln furnace. Are introduced in several places. Also, combustion takes place in conjunction with air rather than oxygen, and air can be drawn from the surroundings, thus reducing the capital investment and operating costs of the oxygen plant for a major part of the overall combustion process when compared to, for example, DIOS. It is preferable to be able to avoid this. Air rather than oxygen can be used because nitrogen content does not have negative consequences due to the volume of nitrogen or reaction with the composite pellets. Low level of pre-reduction and CO in smelter furnace
Compared to prior art treatment methods with high post-combustion, the present invention partially replaces the relatively expensive oxygen requirements in the smelter furnace with the less ambient air in the pre-reduction stage. I have.

Since iron oxide is supplied to the pre-reduction furnace as composite pellets, the smelter furnace top gas is supplied to the pre-reduction furnace rather than having to provide a reducing atmosphere as in many prior art processes. Available for combustion to provide heat.

The method can include forming the composite pellet.

[0024] The iron oxide is preferably an iron ore condensate. In an alternative application, the feed is steel mill solid waste including, for example, dust and iron dioxide containing dust collected and recycled from the process.

The solid carbonaceous reducing agent is preferably a biomass material such as coal or charcoal and / or wood waste.

The composite pellet is preferably 20-40% w / w coal (or equivalent reducing agent), most preferably 25-30% w / w coal. Additional reducing agent can be added directly to the reduction furnace individually, and some added or discharged reducing agent can be added directly to the smelter furnace.

[0027] The carbon content of the direct reduction intermediate product is preferably about 5 to 15% w / w.
The pretreated flux, if included with the directly reduced iron product (having a reduction rate of 80-90%), is preferably conveyed directly to the smelter furnace, and the top gas is fed to the two furnaces It is reused for heating and burning in an integrated installation that is bridged in close proximity, for example by a connecting enclosure or duct. This transport is typically performed in a manner such that the reduced iron product is directly supplied in the indicated temperature range. Alternatively, the pre-reduced iron product and pre-treated flux may be recovered from the pre-reduction furnace (for operational convenience), stored and stored in a hot state, for example, in a refractory lined bottle. It is conveyed as it is, and is then transferred to a smelter furnace at a suitable time. In the present case, it is preferably optimized that some cooling takes place.

The pre-reduction furnace is preferably a rotary kiln with a moving grid preheater (to dry and cure the pellets), but any furnace that achieves the indicated product state Will be usable. Moving grid kilns are suitable alone. However, preferably the green pellets (ie, not dried directly from the pelletizing drum or wheels) are conveyed from the pelletizing plant to a rotary kiln against a moving grid. The maximum temperature in the kiln is preferably 90
It is in the range of 0 ° C to 1400 ° C, but typically close to 1150 ° C to 1350 ° C. The heat required is supplied in enthalpy, for example by the combustion of top gas, optionally supplemented by burners burning coal or natural gas.

[0029] The smelter furnace can be any suitable furnace with oxygenation equipment. Various conventional furnaces, for example, oxygen blowing arc furnace (EAF), submerged arc furnace (
Furnaces such as SAF), blast furnace, energy optimization furnace (EOF), basic oxygen steelmaking (BOS) vessel and extension furnace are suitable. Among these furnaces, furnaces which are considered to be particularly suitable include EOF type side spray hearth furnaces and extension furnaces. The last-mentioned extended arrangement of smelter furnaces could be suitable for the production of liquid steel by allowing two melting zones in relation to composition and temperature. Most of the slag will be removed from the high C-edge to ensure low slag iron (<5% FeO).

The smelter furnace can also allow for the addition of further reducing agent in a lump and / or jet state.

[0031] The molten iron can be steel, semi-steel or pig iron.

Preferably, the slag from the smelter furnace is less than 5% Fe when expressed as FeO.
It has a content, preferably 1.5% or less when measured as FeO, and is thus suitable for cementing by polishing. In its preferred embodiment as an integrated steelmaking method, the present invention more preferably comprises slag recovery and treatment or transport for this purpose. The processing steps typically required would include quenching or granulation to ensure a high glass content (ie, non-crystallization), followed by polishing. This slag preferably has about 5%, most preferably 1.5% or less of an Fe component as measured by FeO. Preferably, this is partially the carbon component of the vessel, the relative strength of the oxygen sprayed and mixed between the molten metal and the slag, the liquid hold-up volume and, if necessary, the carbon reducing agent that becomes the slag phase Is achieved by controlling the injection of

In a preferred embodiment as an integrated steelmaking process, the process preferably further taps the melt, which is further preferably achieved by using additional flux and oxygen as needed. Transfer to the refining plant. Preferably, the slag waste of such other plants is returned to the smelter furnace leading to a "zero" solid waste generation section. Steel contaminants such as S and P are preferably expelled from the processing stage in the slag stream.

Preferably, the top gas waste of such another plant is also returned to the reduction furnace or waste heat recovery system.

In another embodiment, one or multiple smelter furnaces are used, all connected directly to the pre-reduction furnace. Each smelter furnace operates in a two-stage cycle, the first stage being filled with hot DRI and smelting to produce a liquid metal with 1 to 4.5% carbon content, and the second stage from the first stage. The slag is removed, and then the liquid metal is refined and decarbonized by adding a flux and injecting oxygen. During this second stage, the pre-reduction furnace continues to produce high temperature DRI that is transported to another smelter vessel or high temperature holding bin.

Preferably, the apparatus further includes a waste heat boiler or gas turbine that uses the off-gas from the pre-reduction furnace to generate electric or mechanical power, which includes a smelter furnace and a forming device. It is believed to provide sufficient power to generate oxygen for all relevant plants. Hot gas can be supplied directly from a rotary kiln and / or a preheated gas furnace.

Detailed Description of the Preferred Embodiment The integrated carbon-based iron ore processing plant 10 illustrated in FIG. 1 includes a pre-reduction furnace in the form of a tilted rotary kiln 20. Included is a smelter furnace provided with a moving grate 21 and side spray hearth furnace 30 of generally conventional configuration. The two furnaces are connected directly at a link enclosure 25 between the lower discharge end 22 of the rotary kiln pre-reduction unit and the central upper feed port 32 of the smelter furnace.

[0038] The composite pellets are supplied from iron ore agglomerate, coal and binder supply from about 20 to 3 times.
A 5%, preferably 25-30% coal product specification is formed in the pelletizer 40. The pellets are grid-dried together with raw material flux such as lime,
It is supplied to a curing and pre-heating stage. The pre-heated pellets are supplied directly to the rotary kiln pre-reduction unit 20.

In a rotary kiln, the natural gas burner is started and supplemented with heat to maintain an ambient temperature of about 1250 ° C. throughout the length of the kiln, thus substantially reducing iron ore to feed end Directly forms reduced iron (DRI), wherein the degree of reduction is about 80-90% (assuming a degree of metallization of 73-86%) and the carbon content is about 1%.
2%. At about 1050 ° C., this DRI product exits kiln 20 and
It falls into the smelter furnace 30 through the link enclosure 25. Lime flux is also calcined in the rotary kiln and transported to the smelter furnace. Here, oxygen is injected sideways from circumferentially spaced locations 31 and DRI is refined to provide a liquid with a slag having a carbon content of 5% or less and an iron component of 5% or less as measured by FeO. Form molten iron or semi-steel. Oxygen injection is performed from the side into the molten metal. Due to the high pre-reduction of the TRI feed to the smelter furnace 30, the oxygen injection is reduced accordingly and the post-combustion can be controlled at a relatively low 20-30%. The top gas containing carbon monoxide is fed into the rotary kiln 20 via the link enclosure 25 (eg, at about 1600 ° C.) where the top gas is combusted with air and heat generated to maintain kiln temperature. And provide an additional reduction potential difference. Combustion is spaced along the kiln to maintain heat flux using a number of process-type air injectors 23 adapted to draw air from the ambient atmosphere.

A suitable preheating device 21 and prereduction device 20 are similar to the rotary kiln and grate combination used in the pellet plant. Typical dwell times range from 45 to 60 minutes.

A suitable smelter furnace 30 is 8 m in diameter. The slag is collected and transported to a grinding / polishing plant 50 for conversion to cement clinker. The melt is tapped as a hot metal or semi-steel for further refining as required. Slag waste from such other smelting plants is recycled to the smelter furnace 30, and off-gas is recycled to either the pre-reduction unit 20 or the waste heat recovery unit 60. Alternatively, slag waste is used in other additional applications such as soil conditioners or leachate fertilizers.

Useful molten products of the smelter furnace 30 include semi-steel (2% carbon), low silicon high temperature metals (
3.5% carbon) or steel (0.1% carbon), the latter preferably being ROM
Preferably, it is best produced using a two-zone smelter furnace in an ELT configuration or by operating the smelter furnace as a two-step process as described above.

In the exemplary operation of the plant illustrated in FIG. 1, the hourly feed to the rotary kiln 20 is as follows.

Iron ore 160 tons-as composite pellets Coal 60 tons-as composite pellets Raw material flux 40 tons Add binder added during green pelletization Oxygen required in furnace 30 is 100 tph hot metal recovery and 30 tph
Of slag is 25 tons per hour (tph).

The off-gas from the rotary kiln 20 is passed directly through the pre-heating device 21 and then to the waste heat boiler 60. At the processing rates mentioned above, such boilers generate 40 MW (or 150 GJ / hr), which generates 15 MW power.

The smelter furnace can be fed either in batch or continuous operation, for example in the former case by two parallel rotary kiln feeds for each furnace.

The total energy is approximately 15 GJ / t. Greenhouse gases are approximately 1500 kg / t for liquid metals using coal, and zero or slightly negative when using coal.

FIG. 2, shown with similar dashed reference numbers for similar components, represents an alternative embodiment 10 ′, in which a generally horizontally extending rotary kiln 20 includes a blast furnace 20 ′ Has been replaced with The blast furnace is preferably a thermal
It has a number of bustle rings to avoid pinch points and is heated by the partial oxidation of natural gas or smelter gas at each bustle ring. The atmosphere is reduced at the bottom and neutral at the top. Natural gas is preferred to avoid dust problems in the blast furnace, while some recycled off-gas is used via the ring enclosure 25 'for temperature control. The supply of natural gas has a value of 2 GJ / tHM. Solids residence time is typically 60-90 minutes.

An alternative means of providing part of the enthalpy for the blast furnace is to use the blast furnace top gas which is reheated and injected into the bustle ring using a compressed gas injector or mechanical blower. is there.

A suitable temperature profile for the blast furnace 20 ′ is shown in FIG.

The purified off-gas from the smelter furnace 30 is used for heating the blast furnace. If it is necessary to use off-gas from the smelter furnace, it is possible to directly heat the burner on the waste heat boiler 50 after scrubbing in advance if it is necessary to remove chlorine by-products in order to reduce the generation of dioxins.

The greenhouse gas emissions for the integrated configuration illustrated in FIG. 2 are about 1500 k / t, compared to about 2500 kg / t for the most conventional blast furnace basic oxygen furnace integrated steelmaking plant.
Preliminary calculations suggest that it can be as low as g / t. Relative capital investment costs are partially due to displacement of the substitutes for cement made by conventional processing methods, and in part by conventional lime kilns, coke ovens, pellet plants, blast furnaces, stoves, BOFs and power plants. Is to replace the equipment shown in FIG.

The processing method of the preferred embodiment would be ideal for charcoal-based steelmaking which avoids the low strength problems of charcoal in blast furnaces. Other advantages include high reactivity, low sulfur, and low ash in charcoal. This method consumes only renewable energy and therefore reduces or reduces greenhouse gas emissions (which are negative due to the reliability of wood tar and other by-products from coal production). I do.

[Brief description of the drawings]

 The detailed description particularly refers to the following figures:

FIG. 1 utilizes a rotary kiln for the pre-reduction stage;
1 is a block diagram of an integrated coal-based iron ore processing integrated plant according to a first embodiment with both aspects of the present invention.

FIG. 2 is a similar view of a second embodiment utilizing an upright furnace for the pre-reduction stage.

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Claims (42)

[Claims] 1. A method for treating iron oxide to produce an iron product, wherein a composite pellet formed of iron oxide and a solid carbonaceous reducing agent is treated in a pre-reduction furnace to reduce the degree of reduction to 75%. Forming the above directly reduced iron product, conveying the directly reduced iron product to a smelter furnace at a temperature in the range of 700 ° C. to 1400 ° C., and transferring the direct reduced iron product in the smelter furnace Melting with the added oxygen or oxygen / air mixture to form an iron melt containing a top gas containing carbon, slag and carbon monoxide, recovering the iron melt from the smelter furnace, the pre-reduction furnace Provided by heat of said top gas from a smelter furnace using air or oxygen at least partially. 2. The method of claim 1, wherein said solid carbonaceous reducing agent comprises charcoal. 3. The method of claim 1 or 2, wherein the temperature at which the direct reduced iron product is conveyed to the smelter furnace is in the range of 800 ° C to 1100 ° C. 4. The method of claim 1, 2 or 3, wherein the gas composition in the pre-reduction furnace minimizes or avoids excessive re-oxidation of the reduced pellets. 5. The method of claim 1, wherein the off-gas from the pre-reduction furnace is recovered in a means for generating energy from the off-gas. 6. The method of claim 5, wherein said energy generating means is a waste heat boiler or a gas turbine. 7. Conveying one or more flux raw materials to a pre-reduction furnace, preparing said raw materials for internal melting, and then passing the raw materials through the smelter furnace at an elevated temperature. The method of any of the preceding claims. 8. The method according to claim 1, wherein the degree of reduction of the intermediate DRI product is in the range of 80 to 90%. 9. The method according to claim 1, wherein the combustion of the top gas is performed inside a pre-reduction furnace and is introduced at a plurality of points spaced around the pre-reduction furnace. 10. The method of claim 1, wherein the combustion of the top gas is performed with air. 11. The method of claim 1, further comprising forming the composite pellet. 12. The method according to claim 1, wherein the iron oxide is an iron ore condensate. 13. The method according to claim 1, wherein the iron oxide is a steel mill solid waste including dust-containing iron oxide. 14. The method according to claim 1, wherein the solid carbonaceous reducing agent is a biomass material such as coal or charcoal and / or wood waste. 15. The method of any of the preceding claims, wherein the composite pellets are 20-40% w / w coal (or equivalent reducing agent). 16. The method of claim 15, wherein said composite pellet is 25-30% w / w coal. 17. The direct reduction intermediate having a carbon content of about 5 to 15% w.
The method of any of the preceding claims, wherein / w. 18. The directly reduced iron product and, if included, preheated flux, are conveyed directly to the smelter furnace where the top gas is integrated with the two furnaces adjacent to each other. The method according to any of the preceding claims, wherein the method is reused for heating and burning in a gasification facility. 19. The method further comprising transferring the pellet green from a pelletizing plant via a transfer grid to a rotary kiln including the pre-reduction furnace.
A method according to any of the preceding claims. 20. The method according to claim 1, wherein a maximum temperature in the kiln is in a range of 900 ° C. to 1400 ° C. 21. The method according to claim 1, wherein the iron melt is steel, semi-steel or pig iron. 22. The method according to any of the preceding claims, wherein the slag from the smelter furnace has less than 5% Fe component measured on FeO. 23. The method of claim 22, wherein said Fe component is less than 1.5% measured on FeO. 24. The method of claim 23, further comprising tapping the melt and further refining it using additional flux and oxygen as needed, preferably to a nearby plant. The method described in each section. 25. The method of claim 24, comprising returning the slag waste of the plant to a smelter furnace. 26. The method according to claim 24, comprising returning the top gas waste of the plant to a pre-reduction furnace or a waste heat recovery system. 27. An integrated apparatus for treating iron oxide to produce an iron product, comprising treating a composite pellet formed of iron oxide and a solid carbonaceous reducing agent to reduce the degree of reduction to 7%.
A smelter comprising: a pre-reduction furnace for forming a directly reduced iron product in which the pellets contain residual carbon in excess of 5%; a smelter; and means for transporting oxygen or an oxygen / air mixture to the smelter. A furnace for transferring the direct reduced iron product from the pre-reduction furnace to a melting chamber at a temperature in the range of 700 ° C. to 1400 ° C., wherein a smelter furnace is provided with added oxygen, optionally electrical energy, in the melting chamber. Means for melting the direct reduced iron product to form an iron melt containing carbon, slag, and top gas having a carbon monoxide: carbon dioxide ratio of 1.0 or more on a volume ratio basis; An apparatus comprising: means for recovering molten iron from the melting chamber; and means for supplying heat to the pre-reduction furnace at least partially from heat from the smelter furnace and combustion of the top gas. 28. The means for transporting the direct reduced iron product is configured such that the temperature at which the direct reduced iron product is transported to a smelter furnace is in the range of 800 ° C. to 1100 ° C. 28. The apparatus of claim 27, wherein 29. The apparatus according to claim 27, further comprising means for generating electric or mechanical force using off-gas from the pre-reduction furnace. 30. The means for generating is a waste heat boiler or a gas turbine.
30. The device according to claim 29. 31. The apparatus of claim 31, further comprising means for transporting one or more raw materials for the flux to the pre-reduction furnace, wherein the raw materials are prepared for internal melting and then passed through a smelter furnace at a high temperature. 31. The device according to any one of 27 to 30. 32. The apparatus according to any one of claims 27 to 31, wherein the degree of reduction of the intermediate DRI product is configured to be in the range of 80 to 90%. 33. The apparatus of claim 27, further comprising means for forming said composite pellet.
33. The apparatus according to any one of claims to 32. 34. The pre-reduction furnace and the smelter furnace are adjacent to each other in an integrated facility, and thus, when used, the direct reduced iron product and 28. The treated flux is conveyed directly to the smelter furnace.
34. The apparatus according to any one of claims 33. 35. The furnace is bridged by a link enclosure or duct.
The device according to claim 34. 36. Apparatus according to any one of claims 27 to 35, wherein the pre-reduction furnace is a rotary kiln with a grid preheater. 37. The apparatus according to any one of claims 27 to 36, wherein the smelter furnace is an EOF type side-discharge hearth furnace and a square furnace. 38. Means for tapping the melt from the smelter furnace and further refining using any additional flux and oxygen as required arranged to receive the tapped melt. Apparatus according to any one of claims 27 to 37, comprising a plant to perform. 39. The apparatus of claim 38, further comprising means for returning said other plant slag waste to said smelter furnace. 40. Apparatus according to claim 38 or 39, further comprising means for returning top gas waste from said other plant to said pre-reduction furnace or waste heat recovery system. 41. The plurality of smelter furnaces operate in a two-stage cycle, the first stage being filled with high temperature DRI and smelting to produce a liquid metal having a carbon content of 1 to 4.5%. 41. Apparatus according to any one of claims 27 to 40, wherein the two stages remove the slag from the first stage, then refine the liquid metal and decarbonize by adding flux and oxygen injection. 42. The refining is carried out in a two-stage cycle, the first stage being filled with hot DRI and refining to produce a liquid metal with a carbon content of 1 to 4.5%, the second stage being a second stage. 27. The method according to any of the preceding claims, wherein the slag from one stage is removed and then the liquid metal is refined and decarbonized by adding flux and oxygen injection.