CN105723002B - The manufacture method and manufacturing equipment of reduced iron - Google Patents

The manufacture method and manufacturing equipment of reduced iron Download PDF

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Publication number
CN105723002B
CN105723002B CN201580002585.3A CN201580002585A CN105723002B CN 105723002 B CN105723002 B CN 105723002B CN 201580002585 A CN201580002585 A CN 201580002585A CN 105723002 B CN105723002 B CN 105723002B
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reduction
furnace
product
rotary
raw material
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CN105723002A (en
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桑内祐辉
真壁亮司
山崎强
铃木聪
高桥茂树
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Nippon Steel Corp
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Nippon Steel Corp
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/14—Multi-stage processes processes carried out in different vessels or 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
    • C21B13/0073—Selection or treatment of the reducing gases
    • 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
    • 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
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/10—Details, accessories, or equipment peculiar to furnaces of these types
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft 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
    • C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
    • C21B13/085—Making spongy iron or liquid steel, by direct processes in rotary furnaces wherein iron or steel is obtained in a molten state
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2300/00—Process aspects
    • C21B2300/02—Particular sequence of the process steps
    • 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
    • F27B3/12—Working chambers or casings; Supports therefor
    • F27B2003/125—Hearths
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27M—INDEXING SCHEME RELATING TO ASPECTS OF THE CHARGES OR FURNACES, KILNS, OVENS OR RETORTS
    • F27M2003/00—Type of treatment of the charge
    • F27M2003/16—Treatment involving a chemical reaction
    • F27M2003/165—Reduction
    • 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

Abstract

Even if fluctuate the high powdery raw iron oxide material inferior of big raw material, oxidizability using character, on the premise of existing rotary hearth furnace is not transformed on a large scale, only by setting up cheap and readily processing reduction apparatus, the reduced iron of high metal rate also can be stably manufactured.The manufacture method of the present invention is the reduced iron manufacture method reduced using the reduction furnace in two stages to blocking thing, the blocking thing be by the raw material containing iron oxide and reducing material mix and carry out it is Briquetting obtained from, the reduction furnace for being used as the 1st stage by (i) uses rotary kiln bed reduction furnace, (ii) to be used as the 2nd reduction furnace by rotary furnace formula of the CO gas concentrations enrichment in the reducing atmosphere of prescribed limit or vertical reduction furnace, can efficiency manufacture the reduced iron of high metal rate well.And then, it is classified by (iii) the 1st reduction product for obtaining the rotary kiln bed reduction furnace using the 1st stage, only the powdery product (iv) of low metal rate are reduced with rotary furnace formula reduction furnace, are granulated, can efficiency obtain more than high metal rate and certain particle diameter reduced iron well.

Description

The manufacture method and manufacturing equipment of reduced iron
Technical field
The present invention relates to the manufacture method of reduced iron and manufacturing equipment.More particularly to not because of the variation of raw material character Can stably efficiency obtain well high metal rate reduced iron reduced iron manufacture method and manufacturing equipment.
Background technology
In recent years, caused dust (dust) class (blast furnace powder for including iron oxide in iron steel process is made is utilized Dirt, converter dust etc..Hereinafter sometimes referred to high-quality dust (class).), the powdery raw iron oxide material of powder iron ore class etc. (has below When be referred to as high quality powdered raw iron oxide material.) be widely used to manufacture the method for reduced iron.
Manufacture method as such reduced iron, it is known that following methods：By the powdery oxygen of Magnetite (processed) dirt, iron ore etc. Change the reducing material mixing of iron material and carbonaceous, implement Briquetting processing and form particle (pellet) or agglomerate (briquette) the blocking thing of shape, the blocking thing is continuously added in the reduction furnaces such as the rotary hearth furnace of siege movement Heat is come the method (such as patent document 1) that reduces；After the reducing material of powdery raw iron oxide material and carbonaceous is mixed, with revolution Stove (rotary kiln:Rotary kiln) method (such as patent document 2) that is heated to reduce.
Receive recycling promotion and the zero-emission ambition in nearest ironworks processed, be not only in iron steel process is made The high-quality dust of by-product, from the high melting furnace dust of the containing ratio of melting furnace, the slag composition of electric furnace by-product and electric furnace dust, In rolling process the mill scale of by-product, in pickling and neutralization step the pickling of by-product and in and sludge etc. poor quality Powdery raw iron oxide material also begins to use as the raw material of reduction iron.
Usually, such powdery raw iron oxide material inferior, compared with high-quality dust, raw material oxidizability is high, therefore as To reduce the raw material of iron in use, in order to which the degree of metalization of product reduction iron (product degree of metalization) is maintained at into phase Same level, heating reduce the load increase in process.Here, raw material oxidizability (is only called " oxidizability " sometimes.) it is to use quality The index that percentage defines, the quality percentage be the present actual oxygen amount combined with iron relative to the iron content in raw material into The quality percentage for the theoretical oxygen amount that can be combined when dividing (metallic iron, wustite, magnetic iron ore, bloodstone) to be all changed into bloodstone Rate.In addition, product degree of metalization is the finger defined with the metallic iron in product reduction iron relative to the quality percentage of total iron point Mark.In order to reduce the load that reduced iron is carried out to smart reduction in rear process, it is expected that product degree of metalization is higher.
Moreover, such powdery raw iron oxide material inferior, the fluctuation of composition is also bigger than high-quality dust, therefore heats reduction The amplitude of fluctuation of load in process also becomes big.
I.e., so far, reduction is being manufactured by the high quality powdered raw iron oxide material of high-quality dust-like, powder iron ore class etc. In the existing process of iron, if utilizing above-mentioned powdery raw iron oxide material inferior, then need to seek to be used to tackle to add The ability of the increase of load in thermal reduction process and the fluctuation for tackling raw material character strengthens countermeasure.
Citation
Patent document
Patent document 1：Japanese Unexamined Patent Publication 2003-293020 publications
Patent document 2：Japanese Unexamined Patent Publication 2001-280849 publications
Patent document 3：Japanese Unexamined Patent Publication 2000-160219 publications
Patent document 4：Japanese Unexamined Patent Publication 2012-126963 publications
Patent document 5：Japanese Unexamined Patent Publication 2010-222667 publications
Patent document 6：Japanese Unexamined Patent Application 59-25910 publications
The content of the invention
When using rotary kiln bed reduction furnace manufacture reduced iron, the manufacturing capacity of reduced iron, i.e. time per unit exists The amount that iron oxide in stove in raw material is reduced mainly is determined by the hearth area and furnace temperature of revolution siege.In actual job, In order that production efficiency maximizes, furnace temperature is usually improved as far as possible in the range of equipment restriction and carrys out operation.
As it was previously stated, recently, promoting using powdery raw iron oxide material inferior as reduction iron raw material, it is necessary to make With existing rotary hearth furnace come reduction-oxidation degree high raw material than ever.
In the case of powdery raw iron oxide material inferior as use, in order to with current identical degree of metalization by The raw material manufacture reduced iron of more high oxidation degree, the necessary reduction quantitative change in reduction furnace are more.But furnace temperature is difficult to than entering one at present The situation that step improves is more, in addition, the hearth area of revolution siege is also difficult to easily expand.Therefore, present situation is to extend reduction Holdup time of the iron raw material in reduction furnace tackles.
As a result, the increase of the usage amount along with powdery raw iron oxide material inferior, the productivity ratio of reduced iron reduces. Moreover, powdery raw iron oxide material inferior, not only oxidizability is high, and the fluctuation of the raw material character in same breed is also big.The opposing party Face, holdup time of the blocking thing in rotary hearth furnace when reducing iron is shorter, about 15~25 minutes or so, chases after From the fluctuation of raw material character change the recovery time in practical operation it is extremely difficult.
Therefore, powdery raw iron oxide material inferior is being used, is being manufactured when meeting the required value of product degree of metalization also In the case of former iron, it is necessary to consider fluctuating to carry out the operation with surplus capacity for raw material character.The result is that, it has to enter Row operation corresponding with the raw material oxidizability of the upper limit of fluctuation, overall productivity ratio can reduce.
Built with the reduction reaction of the blocking thing of powdery iron oxide of the carbon material as reducing material, by being present in Carbon monoxide in the stomata of blocking thing also carried out the iron oxide of bloodstone, magnetic iron ore, wustite etc. originally.
The carbon monoxide that is played a role as reducing material, it is the interior carbon material being loaded in blocking thing in the reaction system In carbon and the carbon dioxide that is present in stomata reacted and generated.(Bu Shi reacts for the carbon monoxide reaction of formation (Boudouard reaction), C+CO2+ Δ Q=2CO) be the endothermic reaction, therefore in order that reduction reaction carry out, it is necessary to from Continue to supply the heat of compensatory reactionBu Changfanying heat in the outside of blocking thing.
Here, the blocking thing of reduction iron raw material is usually the porous plastid that the porosity is more than 30%, its is apparent Thermal conductivity ratio is small by average the predicted value of composition, therefore the conduction heat transfer in blocking thing is very slow.
That is, in the reduction reaction of the blocking thing in rotary hearth furnace, radiation is passed through from furnace atmosphere to blocking thing surface The heat of heat transfer supply turns into the rate-determining step by entirety (referring for example to special to the conduction heat transfer process conducted inside blocking thing Sharp document 3 and 4).
Patent Document 3 discloses in order to improve the internal heat transfer speed of the blocking thing of iron ore built with carbon material And provide carbon material, ore character method.In addition, Patent Document 4 discloses the wire addition that mixing promotes heat transfer The method of thing.Which kind of but no matter in method, all not yet inherently suppress to tie in iron oxide while reduction reaction The oxygen of conjunction departs from the rising of the caused porosity.
As long as following relations are not cut off, i.e. by the progress of such reduction reaction, the porosity of blocking thing increases, and makees For result, internal heat conduction velocity reduces this relation, in order that with as rotary hearth furnace based on radiant heating The reduction furnace of body promotes reduction reaction, it is necessary to and continue furnace temperature higher, in working continuously under the high furnace temperature, fire proofed wood The load of material becomes big, it is possible to which due to maintenance, running rate reduces.
Here, consider by the extension of rotary hearth furnace main body or set up to compensate the powdery oxygen inferior with high oxidation degree Change the situation of the scarce capacity of the associated existing rotary hearth furnace of use of iron material.
Though the powdery raw iron oxide material inferior of high oxidation degree, in the final stage of rotary hearth furnace, reduced iron are used Degree of metalization reached at least 60% or so, while the porosity also becomes big.That is, rotary hearth furnace final stage time Point, the pyroconductivity of reduced iron fully diminish, when the rotary furnace that will there was only radiant heat transfer to the heat supply mechanism of blocking thing Pool furnace extends, and when being reduced to attempt the essence of reduced iron, can easily predict equipment and become very large.
In addition, as not by the expansion of reduction furnace and in two stages the step of promote reduction reaction method, Patent document 5 and 6 is on the books.
In following methods described in patent document 5：Using bed reaction device is flowed, bloodstone or goethite are used in advance Reducing gas is restored to magnetic iron ore, thereafter, the mixing formed to adding carbonaceous reducing material into obtained semi-reduction product Thing irradiating microwaves are heated, and thus further reduction, obtains metallic iron.
In this case, although the equipment scale of the flowing bed reaction device for reducing in advance can be suppressed, use Microwave irradiation has carried out smart reduction, if considering the energy and incident efficiency required for reduction, predict with being easy for needed for Power-supply device become it is too much.
Following technologies are proposed in patent document 6：Exhaust from the rotary furnace as reduction furnace is being used for raw material When preheating and prereduction, increase the carbon monoxide content in exhaust, to accelerate prereduction.Thus, it is to be turned round with improving Reduction efficiency in stove is as target.But the technology is and the rotary furnace premised on the reduction in rotary furnace Delivery temperature it is lower than in-furnace temperature, therefore easily speculate arrive：The effect for the prereduction that can be reached using the exhaust, with It is smaller that reduction furnace is set to two stage phases in itself.In addition, not by powdery oxygen inferior under technical level at that time Change using for iron material and be used as premise, therefore the technology can not be applied to powdery raw iron oxide material inferior as former state.For making With powdery raw iron oxide material inferior, although using the thermal efficiency, reduction efficiency during reduction efficiency good rotary kiln bed reduction furnace It is good, but also exist to the heat conductivity inside the blocking thing of raw material deteriorate the problem of so as previously described.
For the present invention in view of the present situation and problem of the reduced iron manufacturing technology of the above, the purpose is to provide to solve following classes The manufacture method and manufacturing equipment of the reduced iron of topic, the problem are：Even if big raw material and/or oxygen are fluctuated using character The high powdery raw iron oxide material inferior of change degree, does not transform existing rotary hearth furnace, only by cheap and easy on a large scale Smart reduction apparatus is set up, so that it may stably manufactures the reduced iron of high metal rate.
The present inventor etc. is studied the method for solving above-mentioned problem with keen determination.As a result, obtain following opinion.
(a) firstly it is found that：The raw material and carbonaceous that powdery is contained into iron oxide reducing material mixing, implement it is Briquetting The blocking thing formed is handled (below, to be in this manual referred to as " the blocking thing of raw material ".) reduction in, reduction reaction carry out While the porosity increase, from the conduction heat transfer of blocking thing surface internally turn into reduction reaction rule speed process the problem of, can By the way that reduction process is divided into two stages to solve.In reduction (the hereinafter referred to as the 1st reduction, by going back now in the 1st stage Former stove is referred to as the 1st reduction furnace.) in, the major part of the iron oxide in the blocking thing of raw material is reduced.In this case, what is obtained goes back The reduction product obtained in the 1st reduction (is referred to as the 1st reduction product by former product.) high porosity, therefore Conductivity of heat is poor in the state of former state.It has further been found that：If using high porosity can be applied flexibly in promote reduction reaction side Method carries out the reduction in the 2nd stage, then can stablize and expeditiously manufacture the reduced iron of high metal rate.
(b) also found：In the 1st reduction, due to the porosity also low, conductivity of heat, therefore use of the blocking thing of raw material Rotary kiln bed reduction furnace (RHF), (the hereinafter referred to as the 2nd reduction, is referred to as the 2nd to the reduction in the 2nd stage by reduction furnace now Reduction furnace.) in, because the 1st reduction product is changed into high porosity, easily make furnace reduction gas by stomata and internally Diffusion, improves reproducibility, therefore by using rotary furnace, shaft furnace, can manufacture high metal rate with high thermal efficiency Reduced iron.
In addition, in the 2nd reduction, the stomata of reducibility gas from the 1st reduction product internally permeates, and will aoxidize Iron reduces.Therefore, it is necessary to certain density reducibility gas in the 2nd reduction.Then, the inventors discovered that, by making the 2nd The concentration of CO gases in reducing atmosphere in reduction is below the volume % of more than 10 volume % 85, can efficiency well will 1st reduction product reduction.
(c) the 1st reduction product also includes the reduced iron of low metal rate.Generally, the reduced iron of low metal rate is strong Spend low, efflorescence when being discharged from the 1st reduction furnace.High metal rate is obtained in the 2nd reduction furnace, the result of efflorescence is also also The particle diameter of former iron diminishes, therefore has had the anxiety that dirt reoxidizes during operation in rear process.On the other hand, degree of metalization is high Reduced iron due to intensity it is high thus be difficult to efflorescence.Consequently found that：If the thing for only reducing efflorescence among product by the 1st Matter reduces in the 2nd reduction furnace for having used rotary furnace, then can promote reduction reaction and produce the reduction being granulated Iron.
But the too more progress that can also hinder the 2nd reduction of the material of efflorescence.The present inventor confirms：As In the case that 2 reduction furnaces use rotary furnace formula reduction furnace, if the reduction containing less than 75% particle diameter less than 3mm generates The reduction product of thing, then the 2nd reduction is sufficiently carried out in rotary furnace formula reduction furnace.
(d) and then, in the case where using rotary furnace as the 2nd reduction furnace, when in order to promote the small low metal of particle diameter The reduction of the reduced iron of rate and when improving furnace temperature, attachment as stove ring formation can be generated in stove.It is known to generate the stove During kiln ring formation, become to be difficult to continue operation sometimes.Consequently found that：If it is higher than 1100 by the in-furnace temperature control of rotary furnace DEG C and less than 1200 DEG C, then can promote reduction reaction and do not generate stove ring formation and by reduced iron spheroidizing.
The present invention is completed based on above-mentioned opinion, and its main idea is as follows.
(1) a kind of manufacture method of reduced iron, carries out the reduction treatment in continuous two stages to blocking thing, it is described into Block thing be by the raw material containing iron oxide and reducing material mix and carry out it is Briquetting obtained from, the feature of the manufacture method It is,
(i) rotary kiln bed reduction furnace is used in the 1st reduction treatment, then,
(ii) rotary furnace formula or vertical reduction furnace are used in the 2nd reduction treatment, in the 2nd reduction treatment, reduction The concentration of CO gases in atmosphere is below the volume % of more than 10 volume % 85.
(2) manufacture method of the reduced iron according to (1), it is characterised in that generated in above-mentioned 1st reduction treatment Reduction product be the 1st reduction product degree of metalization be below the mass % of more than 65 mass % 90.
(3) manufacture method of the reduced iron according to (1) or (2), it is characterised in that in above-mentioned 2nd reduction treatment It is middle handled using rotary furnace formula reduction furnace it is above-mentioned 1st reduction product in the case of, the atmosphere in the rotary furnace formula reduction furnace Temperature is more than 1100 DEG C and for less than 1200 DEG C.
(4) manufacture method of the reduced iron according to any one of above-mentioned (1)~(3), it is characterised in that will be upper State the 1st reduction product classification generated in the 1st reduction treatment so that the reduction product under classifying screen only contains 75 matter The particle diameter for measuring below % is less than 3mm reduction product, the 1st for reducing product by the 2nd and being stayed in above-mentioned classification on sieve Product mixing is reduced, the 2nd reduction product is that the reduction under above-mentioned classifying screen is generated using rotary furnace formula reduction furnace Thing is carried out obtained from above-mentioned 2nd reduction treatment.
(5) manufacture method of the reduced iron according to any one of (1)~(4), it is characterised in that above-mentioned containing aerobic The raw material for changing iron is including at least melting furnace dust, electric furnace dust, mill scale, pickling and neutralizes any of sludge Raw material.
(6) a kind of manufacturing equipment of reduced iron, it is the reduction for being reduced the blocking thing of raw material using continuous two reduction furnaces Iron manufacturing apparatus, the blocking thing of raw material are to mix the raw material containing iron oxide and reducing material and carry out Briquetting and obtain Arrive, the manufacturing equipment is characterised by possessing：
(a) the rotary kiln bed reduction furnace as the 1st reduction furnace, it is used for the blocking thing reduction of above-mentioned raw materials；With
(b) the rotary furnace formula as the 2nd reduction furnace or vertical reduction furnace, it is used for will be raw in above-mentioned 1st reduction furnace Into reduction product be the 1st reduction product further reduce.
(7) manufacturing equipment of the reduced iron according to above-mentioned (6), it is characterised in that be also equipped with：
By the classifying equipoment of the above-mentioned 1st reduction product classification；With
The 1st reduction product being in above-mentioned classifying equipoment under sieve is fitted into above-mentioned 2nd reduction furnace, and will be The 2nd reduction product generated in above-mentioned 2nd reduction furnace and the 1st reduction product stayed in above-mentioned classifying equipoment on sieve The equipment of mixing, rotary furnace formula reduction furnace is used as above-mentioned 2nd reduction furnace.
According to the present invention, without using the big rotary kiln bed reduction furnace of equipment scale, and do not have to improve reaction speed And improve furnace temperature, it becomes possible to the reduced iron of high metal rate is easily manufactured by powdery raw iron oxide material inferior.As a result, The equipment investment for large-scale rotary kiln bed reduction furnace can be avoided.
Brief description of the drawings
Fig. 1 is the concept map for representing the mode of the present invention.
Fig. 2 is the figure for the experimental result for representing embodiment 1.
Fig. 3 is the figure for the experimental result for representing embodiment 2.
Fig. 4 is represented the concept map of the mode in the case of the 1st reduction product classification.
Fig. 5 is the figure for the experimental result for representing embodiment 5.
Fig. 6 is to represent to sieve lower classification ratio (quality %) and the figure of the relation of end article degree of metalization (%).
Embodiment
The manufacture method (hereinafter sometimes referred to " manufacture method of the present invention " of the reduced iron of the present invention.), it is to use two ranks The reduced iron manufacture method that is reduced to blocking thing of reduction furnace of section, the blocking thing be by the raw material containing iron oxide and Reducing material mix and carry out it is Briquetting obtained from, the manufacture method is characterised by,
(i) the 1st reduction furnace is used as, using rotary kiln bed reduction furnace, then,
(ii) the 2nd reduction furnace is used as, uses rotary furnace formula or vertical reduction furnace, in the 2nd reduction treatment, reduction The concentration of CO gases in atmosphere is set to more than 10 volume % below 85 volume %.
The manufacturing equipment (hereinafter sometimes referred to " manufacturing equipment of the present invention " of the reduced iron of the present invention.), it is to use two ranks The reduced iron manufacturing equipment that is reduced to blocking thing of reduction furnace of section, the blocking thing be by the raw material containing iron oxide and Reducing material mix and carry out it is Briquetting obtained from, the manufacturing equipment is characterised by possessing：
(a) by the rotary kiln bed reduction furnace in above-mentioned blocking thing is taken in and is reduced the 1st stage；With
(b) back segment of the rotary kiln bed reduction furnace is arranged at, the reduced iron that will be discharged from the rotary kiln bed reduction furnace Rotary furnace formula take in and further reduce the reduced iron, the 2nd stage or vertical reduction furnace.
Hereinafter, manufacture method of the present invention and manufacturing equipment of the present invention (are collectively referred to as " present invention " by the present invention sometimes.) Illustrate.
The reduction product discharged from the 1st reduction furnace is defined as the 1st reduction product, by what is discharged from the 2nd reduction furnace Reduction product is defined as the 2nd reduction product.In addition, the 2nd will be obtained by the 1st reduction product in the inside of the 2nd reduction furnace The reaction of reduction product is referred to as smart reduction reaction.
Fig. 1 represents to manufacture a mode of the invention for reduced iron using the reduction furnace in two stages.Iron oxide will be contained Raw material and reducing material (carbonaceous reducing material) crush, be kneaded and implement it is Briquetting processing and form the blocking thing of raw material.Will After the blocking thing of raw material is dried, it is fitted into the rotary kiln bed reduction furnace in the 1st stage, is heated, reduced and produced the 1st also Former product.Then, the 1st reduction product is fitted into rotary furnace formula or the vertical reduction furnace in the 2nd stage, heated, Reduce and produce the 2nd reduction product.
In the present invention, in order to by due to caused by the use by powdery raw iron oxide material inferior reduce before raw material height Oxidizability and the degree of metalization of the 1st reduction product that reduces brings up to defined value, set up for will be in rotary kiln bed The 1st reduction product being reduced in reduction furnace additionally heats reduction, furnace temperature than relatively low rotary furnace formula or vertical Reduction furnace.And then in order to promote the smart reduction reaction of the reduced iron inside rotary furnace formula or vertical reduction furnace, by stove The reducibility gas such as the carbon monoxide in interior atmosphere are maintained at high concentration.
Generally, in the reduction reaction in the rotary kiln bed reduction furnace built with the blocking thing of the iron oxide of carbon material, with The reducing gas that built-in carbon is divided into origin is supplied from the inside of blocking thing, therefore the outside atmosphere of blocking thing is anti-to reducing Influenceed caused by answering small to the degree that can ignore.That is, due to being higher than atmosphere pressure from the pressure of gas caused by blocking thing inside Power, therefore, it is difficult to occur from the atmosphere laterally gas intrusion inside blocking thing.
But presumption is arrived：From the 1st reduction product of the 1st reduction furnace discharge as rotary kiln bed reduction furnace, gold Category rate has reached at least 60% or so, and correspondingly the porosity also uprises.Therefore, the present inventor etc. thinks： In the case of will be to reducing the smart reduction of product progress using the made from rotary kiln bed reduction furnace the 1st, in the 2nd reduction furnace, The situation of diffusion inside of the furnace atmosphere gas easily by stomata and to blocking thing be present, can efficiency promote well also Original reaction.
Think, if improving the reducibility gas inside the 2nd reduction furnace of the essence reduction for carrying out the 1st reduction product Concentration, then reducibility gas can to the 1st reduction product diffusion inside and iron oxide is reduced.
In the present invention, the representative of the effective reducibility gas of reduction to the blocking thing of iron oxide built with carbon material Example is CO (carbon monoxide) gas.The CO gas concentrations in rotary kiln bed reduction furnace during usual operation are less than 10 volume %, It is therefore desirable for the concentration of the CO gases of the inside of the 2nd reduction furnace is more than 10 volume %.In addition, the result of the present inventor's research It is, even if excessively improving CO gas concentrations, to promote the effect also saturation, therefore the upper limit of CO gas concentrations is set to of reduction reaction 85% (Fig. 3).
The method for improving the reducibility gas concentration inside the 2nd reduction furnace, can flow into reducibility gas from outside The combustion air ratio of method or the burner in order to keep furnace temperature and make to burn in stove is less than 1 to carry out not exclusively The method of burning.Alternatively, it is also possible to be to reduce product dividually with the 1st while add the carbon material of coal measures, carried out in stove Decompose to produce the method for reducibility gas.
According to the present invention, by reducibility gas necessary to the iron oxide reduction reaction inside the 2nd reduction furnace from blocking thing Outside be supplied directly to the inside of the 1st reduction product, therefore be not necessarily required to cause Bu Shi anti-in the inside of blocking thing Should, it is not necessary to heat necessary to the supply Bu Shi reactions of blocking thing.That is, the in high porosity the 1st reduces product Essence reduction in, can avoid heat transfer rule speed, even can also promote reduction reaction than relatively low furnace temperature.
And then rotary furnace formula or vertical reduction furnace are used by being used as the 2nd reduction furnace, it can obtain：Blocking thing is quiet The rotary kiln bed reduction furnace put and reduced can not be expected, atmosphere gas and the 1st reduction product it is strong mutual Effect.
That is, in the case of rotary furnace formula reduction furnace, by being stirred caused by body of heater revolution the 1st reduction product Mix, in addition, in the case of shaft reduction stove, by from being pressed into gas stream caused by gas and the 1st reduction product into stove Contact, can promote reducibility gas to the 1st reduction product stomata inside diffusion invade.
As previously discussed, in the present invention, in order to promote the reduction reaction in the 2nd reduction furnace, the 1st has effectively been applied flexibly Reduce the situation that product is high porosity.
When reduction reaction is not carried out somewhat in the 1st reduction, the porosity of the 1st reduction product does not fill Divide and become big, be more than atmosphere pressures from the pressure of gas caused by stomata inside, therefore in the 2nd reduction, reducing gas can not Invaded to stomata diffusion inside so as to not carry out reduction reaction.
The present inventor research as a result, the 1st reduction product degree of metalization desired lower limit be 65%.Confirm Arrive：If can ensure that degree of metalization is more than 65%, the fully high porosity can be reached, the reduction reaction energy in the 2nd reduction It is enough to carry out (Fig. 2).
In addition, in the case where the recovery time in making the 1st reduction furnace is fully long, the degree of metalization of the 1st reduction product Close to the metal target rate of the 2nd reduction product.The degree of metalization of the reduced iron usually to circulate in the market is 90% Left and right.If that is, terminate the time point of reduction treatment in the 1st reduction furnace, the degree of metalization of reduced iron up to 90%, Need not then the 2nd reduction furnace be used to carry out smart reduction.
From the point of view of described above, it is desirable to which the 1st degree of metalization for reducing product after the 1st reduction terminates is more than 65% Less than 90%.
In addition, in the case where using the reduction furnace of rotary furnace formula as the 2nd reduction furnace, can be while also primary by the 1st Mixed into thing in rotary kiln reduction stove while promoting its spheroidizing (increase of particle diameter).
In the 1st of high porosity reduces the essence reduction of product, heat transfer rule speed can be avoided, even than relatively low Temperature can also promote reduction reaction, but when the furnace temperature of the rotary furnace formula reduction furnace in the 2nd stage is less than 1100 DEG C, essence is also Former reactivity reduces, therefore furnace temperature is preferably greater than 1100 DEG C.
But when the 2nd stage rotary furnace formula reduction furnace furnace temperature more than 1200 DEG C when, can significantly generate stove knot Circle, therefore furnace temperature is preferably less than 1200 DEG C.
As the raw material containing iron oxide, such as melting furnace dust, electric furnace dust, mill scale, pickling can be used With the powdery raw iron oxide material inferior for neutralizing sludge etc..
Then, said to the 1st reduction product to be classified and be sieved the mode that low-grades are put into the 2nd reduction furnace It is bright.1st reduction product, due to the progress of the reduction reaction inside blocking thing, degree of metalization has reached at least 60% or so, Correspondingly, the porosity of the 1st reduction product uprises.
The present inventor has found based on the situation, if by the 1st reduction product degree of metalization is smaller and the porosity becomes High material is put into the 2nd reduction furnace and further reduced on one's own initiative, it becomes possible to which it is high that efficiency obtains degree of metalization well Reduced iron.In addition, the inventors discovered that, if the 2nd reduction furnace is rotary furnace formula reduction furnace, atmosphere gas is easily from stomata To the 1st reduction product internal penetration and carry out smart reduction.And then find, the 1st of powdery during the progress of reduction treatment Product spheroidizing (particle diameter increase) is reduced, can finally obtain the reduced iron that degree of metalization is high and particle diameter is big.
The character (composition composition, size distribution etc.) of 1st reduction product is the property obtained under common operating condition Shape, it is not limited to specific character.But when powdery of the particle diameter less than 3mm reduces product more than 75 mass % When, heat transfer rule speed can be turned into the rotary furnace formula reduction furnace in the 2nd stage, it is impossible to be fully promoted the atmosphere control of essence reduction The effect of system.
It is therefore preferable that：Product of the particle diameter less than 3mm in 1st reduction product is below 75 mass %.
Moreover, the fine fraction in the 1st reduction product does not carry out reduction reaction, degree of metalization is low, and residual carbon becomes It is more.On the contrary, distinguish：Coarse component in 1st reduction product, fully carries out reduction reaction, and degree of metalization is high and residual Carbon is stayed to tail off.
It is considered that because when the blocking thing of raw material is fitted into the rotary kiln bed reduction furnace in the 1st stage, due to Impact etc., raw material blocking thing efflorescence, the raw material of the efflorescence block heat by the blocking thing of surrounding, and reduction reaction does not have what is carried out Reason.
Therefore, the present inventor expects：1st reduction product is classified, only by the fine-grained composition of the low metal rate under sieving (efflorescence thing) carries out smart reduction with the rotary furnace formula reduction furnace in the 2nd stage and is granulated.
Fig. 4 represents to manufacture reduced iron one using the reduction furnace in two stages.Until the revolution siege with the 1st stage It is identical with the manufacture shown in Fig. 1 untill during the 1st reduction product of formula reduction furnace manufacture.But in the manufacture shown in Fig. 4 In mode, by the 1st reduction product classification, the rotary furnace that low-grades (the efflorescence thing of low metal rate) loaded for the 2nd stage will be only sieved In formula reduction furnace, heated, also obtained the 2nd reduction product originally.
The manufacturing equipment of the manufacture of implementation reduced iron shown in Fig. 4, it is characterised in that possess：
(a) the rotary kiln bed reduction furnace in the 1st stage, it is used for by powdery raw iron oxide material and carbonaceous reducing material Mix and carry out it is Briquetting obtained from the blocking thing of raw material heated, reduced；
(b) classifying equipoment, it is arranged at the back segment of above-mentioned rotary kiln bed reduction furnace, for by from the revolution in the 1st stage Reduction product (the 1st reduction product) classification of hearth reducing furnace discharge；With
(c) the rotary furnace formula reduction furnace in the 2nd stage, it is used to only heat also by the reduction product under above-mentioned sieve It is former.
Classifying equipoment is to generate the reduction that the temperature discharged from rotary kiln bed reduction furnace is 700~1100 DEG C or so The equipment of thing classification, it is therefore desirable to which there is heat resistance.Such as preferably fixed sieve (diagrid (grizzly)), water-cooled rolling Shaft screen (roller screen).Rotary screen can adjust Cut size by changing axle base, therefore be used as classifying equipoment It is preferable.
Sieve top grade (coarse content) has high metal rate, therefore is reduced without essence and pass through its bypass, rear Section, the 2nd reduction product interflow obtained from making it and lower part of screen point being carried out into smart reduction, to form product reduction iron.According to Manufacture shown in Fig. 4, the treating capacity in the rotary furnace formula reduction furnace in the 2nd stage can be reduced, is not only able to make revolution The reduction furnace main body miniaturization of stove formula can also seek the exhaust gas treatment device of the reduction furnace and attaching for heating burner etc. The miniaturization of equipment, the reduction of equipment investment can be brought.
If classification benchmark particle diameter when being classified to the 1st reduction product is set in particulate side, in the 2nd rank Treating capacity in the rotary furnace formula reduction furnace of section is reduced, therefore can make the scale is smaller of the reduction furnace.But on the other hand, The quality ratio of the product less than 3mm in the sieve low-grades (efflorescence thing) handled with rotary furnace formula reduction furnace is (hereinafter referred to as " ratio for being less than 3mm ".) increase, the reduction reaction speed reduction in rotary furnace formula reduction furnace.It is less than as shown in figure 5, working as When 3mm ratio is more than 75%, essence reduction is not carried out.
Fig. 6 expressions sieve lower classification ratio (among the product for supplying to be classified, as the ratio (matter for the product for sieving low-grades Measure %)) with the relation of end article degree of metalization (%).As can be seen from Figure 6, can if the lower classification ratio of sieve is more than 50% Enough ensure the degree of metalization of end article for 80% with
Embodiment
Then, embodiments of the invention are illustrated, but the condition in embodiment is to confirm the implementation of the present invention Possibility and effect and the condition example used, the present invention are not limited by a condition example.The present invention is not being departed from Main idea and reach under the limit of the purpose of the present invention, the present invention can use various conditions.
Embodiment 1
In order to confirm the optimal sharing of load in the 1st reduction furnace and the 2nd reduction furnace, implement experiment with blocking thing (with It is referred to as " block " down.) reduction experiment, the experiment by the use of blocking thing be using to the melting furnace as powdery raw iron oxide material inferior Mix the raw material containing iron oxide that forms of electric furnace dust in dust and coal mix and carry out it is Briquetting obtained from.
The composition of the block of preparation, all it is metal Fe=1%, FeO=35%, Fe in Quality Percentage2O3=34%, C =15%.
Prepare two (A stoves and B stoves) experiment reduction furnaces.A stoves are that furnace gas composition is set into N2：100%th, by stove Temperature remains 1250 DEG C of experiment electric furnace, and B stoves are that furnace gas composition is set into CO：40%+N2：60%th, furnace temperature is kept For 1150 DEG C of experiment electric furnace.The furnace atmosphere of B stoves, strongly reducing atmosphere is in a ratio of with A stoves, but furnace temperature is low 100 DEG C.Will Experiment condition is shown in table 1.
Though in which level, first, block stood in the stove of A stoves as defined in the time make its reaction.In A stoves Furnace temperature it is fully high, be 1250 DEG C, also built with carbon material in block, thus from furnace atmosphere by radiation be delivered to block table The heat in face is conducted to block inside, and carbon material gasification carries out reduction reaction so as to produce CO gases.Reduction so far is anti- It should be referred to as the 1st stage, its later reduction reaction was referred to as the 2nd stage.
In the 2nd stage, finish the part among the block of reduction reaction in the 1st stage, then in identical stove Continue reduction reaction (level 1,3,5) in the A stoves of warm, identical atmosphere.On remaining piece, after the 1st reduction reaction terminates, Moved rapidly into the stove of B stoves, continue reduction reaction (level 2,4,6) in B stoves.
Atmosphere in the stove of B stoves is retained as CO：40%+N2：60% this strongly reducing atmosphere, can expect the stove than A stove The reduction reaction of block is inside carried out soon, therefore in B stoves, furnace temperature is set as to slightly lower temperature, or will set in the reaction time It it is the shorter time to shorten compared to total reaction time with continuing the block of reduction in A stoves.
The 1st stage and the 2nd reduction reaction shown in the expression table 1 of table 2 terminate after block degree of metalization analysis knot Fruit.
First, it is conceived to level 3 and level 4.Level 3 is in N2：100%th, reacted in 1250 DEG C of A stoves 15 minutes Level.On the other hand, level 4 is after reacting 10 minutes first in A stoves, in 1150 DEG C of furnace temperature, strongly reducing atmosphere (CO： 40%) reaction in furnace of B stoves 2.5 minutes, so as to carry out the level of total 12.5 minutes reaction.
In level 4, although compared with level 3, total reaction time is short 2.5 minutes, also, the 2nd reduction furnace Final degree of metalization after furnace temperature is low 100 DEG C, but the 2nd reduction terminates maintains and the identical value of level 3.Show： By will be replaced by strongly reducing atmosphere in stove in the way of reduction reaction, the reaction speed of block is greatly improved
On the other hand, in level 5 and level 6, made for the 1st recovery time extend 2.5 minutes than level 3 and level 4 and enter Same experiment is gone.In this case, shorten total reaction time and the furnace temperature of the 2nd reduction furnace is reduced to 1150 DEG C of water The degree of metalization of standard 6 uprises.
It is considered that because, block higher than level 3 and level 4 in the degree of metalization at the time point that the 1st stage terminated The porosity become big, in 2 reduction reaction, easily to the gas pore diffusion of block, reduction reaction is easier to promote atmosphere gas Reason.
For level 1 and level 2, compare：It is 5 minutes to make for the 1st recovery time, is continued also in A stoves as former state thereafter Product (level 1) and the 2nd stage the reductase 12 .5 minutes at 1150 DEG C in the B stoves of strongly reducing atmosphere obtained from former 5 minutes Obtained from product (level 2) degree of metalization.
In this case, it is different from level 3~6, on the degree of metalization of the 2nd reduction product, continue to reduce in A stoves Level 1 than implemented in B stoves the 2nd reduction level 2 it is high.Presumption because, the 1st reduction end time point gold It is 40% that it is low, which to belong to rate, and not generating can be such that the reducibility gas in stove expands into the 1st reduction product in the 2nd stage Scattered sufficient stomata.
In level 7, make the recovery time in the A stoves in the 1st stage longer, be 20 minutes.In this case, in the 1st reduction The time point of end, the degree of metalization of the 1st reduction product have reached 90%.Therefore, in this case, it is not necessary to specially add It is sufficient that equipment is to implement the 2nd reduction, the only reduction in the 1st stage of progress.
Fig. 2 is represented：The 1st reduction product that will be obtained in the 1st reduction in A stoves, further (1) continues in A stoves Reduction 5 minutes situation (level 1,3,5,7, in figure zero) and (2) carry out the situation (level of the reduction of 2.5 minutes in B stoves 2nd, 4,6, in figure) under, the reduction in the 2nd stage in A stoves or B stoves terminate after the 2nd reduction product metallization Rate (%) and in A stoves the 1st reduction terminate after the 1st reduction product degree of metalization (%) relation.
It was found from above-mentioned experimental result, in order to improve final degree of metalization, it is necessary in the 1st end time in stage point The degree of metalization of 1st reduction product turns into more than some value.In addition, the degree of metalization in the 1st end time in stage point reaches 90% reduced iron can use as product as former state.
Embodiment 2
Then, the experiment of the influence that furnace atmosphere is given to degree of metalization in the 2nd reduction furnace is evaluated.In this reality 2 (A stoves and B stoves) experiment reduction furnaces are also using in testing.A stoves are that furnace gas composition is set into N2：100%th, by furnace temperature 1250 DEG C of experiment electric furnace is remained, B stoves are stove internal control can be made to reducing atmosphere and furnace temperature is remained into 1150 DEG C Experiment electric furnace.The block used is same as Example 1.
In this experiment, in the level of whole, the block of 10 minutes has been made in the 1st stage in A reaction in furnaces quickly to B Moved in stove, the 2nd reduction reaction is carried out in B stoves.In each level, make CO change in concentration in B stoves for 40%, 70%, 85%th, 90%, to evaluate the influence to caused by the degree of metalization of block.Each experiment condition is shown in table 3.Wherein, the B in the 2nd stage The level 4 that CO concentration in stove is 40% is and the identical of the level of embodiment 14.
Table 4 shows experimental result.By comparing level 4a, 4b and level 4, when improving the CO concentration in B stoves, 2nd stage terminate after degree of metalization also improve.But CO concentration is increased and turn into 90% level 4c gold Category rate is and CO：85% level 4b identical values.
Fig. 3 represent level 4,4a, 4b, 4c the 2nd reduction terminate after the 2nd reduction product degree of metalization (%) and The relation of CO concentration (%) in 2nd reduction furnace (B stoves).
As can be seen from Figure 3, by increasing the CO concentration in the 2nd reduction furnace, degree of metalization also increases, but even if CO concentration Be formed as strongly reducing atmosphere more than 85%, the effect also almost do not given to degree of metalization.
Embodiment 3
Prepare 2 (A stoves and B stoves) experiment reduction furnaces.Here A stoves are that furnace gas composition is set into N2：100%th, Furnace temperature is remained to 1250 DEG C of rotary kiln bed reduction furnace, B stoves are that furnace gas composition is set into CO：30%+N2：70%th, Furnace temperature is remained to 1150 DEG C of 120 × 1200mmH of φ small test shaft (tower) furnace.The furnace atmosphere of B stoves is compared with A stoves For strongly reducing atmosphere, but furnace temperature is low 100 DEG C.
Melting furnace dust (powdery raw iron oxide material inferior) and coal are mixed and carries out Briquetting and obtains the blocking thing of raw material (in terms of quality %, metal Fe：1%th, FeO：38%th, Fe2O3：31%th, C：14%) the blocking thing of the raw material, is used into A stoves first (the 1st stage) is reduced, and produces the 1st reduction product.This implements the 1st also by the 1st reduction product input B stoves The essence reduction (the 2nd reduction) of former product.
Smart reducing condition is as follows.
Shaft (tower) furnace：120 × height of internal diameter 1200mm
Furnace temperature：1150℃
Furnace atmosphere：CO 30%+N270%
Experiment condition is shown in table 5.
No matter in which level, first, as the reduction in the 1st stage, when making as defined in reaction in furnace of the block in A stoves Between.
Then, in the 2nd stage, the part among the block of reduction reaction in the 1st stage is finished then identical Furnace temperature, the interior continuation reduction reaction (level 1,3,5) of the A stoves of identical atmosphere.On remaining piece, after the 1st reduction reaction terminates Quickly moved into the stove of B stoves, continue reduction reaction (level 2,4,6) in B stoves.
Atmosphere in the stove of B stoves is retained as CO：30%+N2：70% this strongly reducing atmosphere, can expect than in A stoves The reduction reaction of block is carried out in stove soon, therefore in B stoves, furnace temperature is set as to slightly lower temperature, or will set in the reaction time It is set to the shorter time with so that being shortened with the block for continuing reduction in A stoves compared to total reaction time.
The 1st stage and the 2nd reduction reaction shown in the expression table 5 of table 6 terminate after block degree of metalization analysis knot Fruit.
First, it is conceived to level 3 and level 4.Level 3 is in N2：100%th, reacted in 1250 DEG C of A stoves 15 minutes Level.On the other hand, level 4 is after reacting 10 minutes first in A stoves, in 1150 DEG C of furnace temperature, strongly reducing atmosphere (CO： 30%) reaction in furnace of B stoves 2.5 minutes, so as to carry out the level of total 12.5 minutes reaction.
In level 4, although compared with level 3, total reaction time is short 2.5 minutes, also, the 2nd reduction furnace Final degree of metalization after furnace temperature is low 100 DEG C, but the 2nd reduction terminates is able to maintain that and the identical value of level 3.Show Go out：By will be replaced by strongly reducing atmosphere in stove in the way of reduction reaction, the reaction speed of block is greatly improved.
On the other hand, in level 5 and level 6, made for the 1st recovery time extend 2.5 minutes than level 3 and level 4 and enter Same experiment is gone.In this case, shorten total reaction time and the furnace temperature of the 2nd reduction furnace is reduced to 1150 DEG C The degree of metalization of level 6 uprises.
It is considered that because, it is higher than level 3 and level 4 in the degree of metalization of the 1st end time in stage point, block The porosity becomes big, in 2 reduction reaction, atmosphere gas easily to the gas pore diffusion of block, reduction reaction become easier into Capable reason.
For level 1 and level 2, compare：It is 5 minutes to make for the 1st recovery time, thereafter, is continued as former state in A stoves The system of product (level 1) and the 2nd stage the reductase 12 .5 minutes at 1150 DEG C in the B stoves of strongly reducing atmosphere of reduction 5 minutes The degree of metalization of product (level 2).
In this case, it is different from level 3~6, on the degree of metalization of the 2nd reduction product, continue to reduce in A stoves Level 1 it is higher than the level 2 for implementing in B stoves the 2nd reduction.Presumption because, in the 1st reduction end time point Low degree of metalization is 45%, and not generating can be such that the reducibility gas in stove expands into the 1st reduction product in the 2nd stage The reason of scattered sufficient stomata.
In level 7, make the recovery time in the A stoves in the 1st stage longer, be 20 minutes.In this case, in the 1st reduction The time point of end, the degree of metalization of the 1st reduction product have reached 91%.Therefore, in this case, it is not necessary to specially add It is sufficient that equipment is to implement the rotary kiln bed reduction furnace reduction of the 2nd reduction, only the 1st stage of progress.
Embodiment 4
Melting furnace dust (powdery raw iron oxide material inferior) and coal are mixed and carries out Briquetting and obtains the blocking thing of raw material (in terms of quality %, metal Fe：1%th, FeO：38%th, Fe2O3：31%th, C：14%), by the raw material blocking thing furnace temperature 1250 DEG C rotary kiln bed reduction furnace (the 1st stage) reduced, produce the 1st reduction product.This reduces product by the 1st Put into 300 × 3400mmL of φ small-sized rotary furnace, implement the essence reduction (the 2nd reduction) of the 1st reduction product.
Smart reducing condition is as follows.
Rotary furnace：300 × length of internal diameter 3400mm
The rotating speed of rotary furnace：3.2rpm
1st reduction product input amount：120kg/h
1st reduction product holdup time：20 minutes
Burner fuel：LPG
Combustion air ratio：0.7 (CO concentration in stove：20 volume %)
The result of furnace temperature and essence reduction is shown in table 7.
In level 5-1, the furnace temperature of rotary furnace (the 2nd stage) is set to 1200 DEG C and implements smart reduction.Its result It is degree of metalization+7%, the ratio+24% of particle diameter >=8mm reduced iron, ratio -18% of particle diameter ＜ 3mm reduced iron can Know in the reduction in the rotary furnace in the 2nd stage, reduction reaction and granulation are together carried out.Furthermore along with the 2nd stage The continuation of reduction reaction, generates stove ring formation in rotary furnace, but its growth is slow, by regularly removed in operation and Operation is can continue to, is influenceed slight.
In level 5-2, the furnace temperature of rotary furnace (the 2nd stage) is set to 1250 DEG C and implements smart reduction, but in stove Stove ring formation is generated, and it hastily grows and makes occlusion in stove, therefore become to be difficult to continue operation.
In level 5-3, the furnace temperature of rotary furnace (the 2nd stage) is set to 1100 DEG C and implements smart reduction, but metallized Rate -3%, the ratio+9% of more than particle diameter 8mm reduced iron, the ratio+1% of reduced iron of the particle diameter less than 3mm, it is known that reduction Reaction and granulation are not carried out together.
In level 5-4, the furnace temperature of rotary furnace (the 2nd stage) is set to 1130 DEG C and implements smart reduction.Degree of metalization + 5%, the ratio+19% of particle diameter >=8mm reduced iron, the ratio -13% of particle diameter ＜ 3mm reduced iron, it is known that in the 2nd stage Rotary furnace reduction in, reduction reaction and be granulated together carry out.In addition, the stove in rotary furnace is also not observed The generation of ring formation.
In level 5-5, the furnace temperature of rotary furnace (the 2nd stage) is set to 1170 DEG C and implements smart reduction.Degree of metalization + 6%, the ratio+22% of particle diameter >=8mm reduced iron, the ratio -15% of particle diameter ＜ 3mm reduced iron, it is known that in the 2nd stage Rotary furnace reduction in, reduction reaction and be granulated together carry out.In addition, the stove in rotary furnace is also not observed The generation of ring formation.
Embodiment 5
By melting furnace dust (powdery raw iron oxide material inferior) and coal mix and carry out it is Briquetting and obtain blocking thing (with Quality % is counted, metal Fe：1%th, FeO：38%th, Fe2O3：31%th, C：14%), the returning in 1250 DEG C of furnace temperature by the blocking thing Turn after being reduced in hearth reducing furnace (the 1st stage), implement appropriate classification processing, producing ratio of the particle diameter less than 3mm is 29 mass %, 38 mass %, 65 mass % and 90 mass % the 1st reduction product.By these the 1st reduction products It is fitted into small-sized rotary furnace, implements essence reduction (the 2nd stage).The furnace temperature of the stove is set to 1150 DEG C.
Smart reducing condition is as follows.
Rotary furnace：300 × length of internal diameter 3400mm
The rotating speed of rotary furnace：3.2rpm
1st reduction product input amount：120kg/h
1st reduction product holdup time：20 minutes
Burner fuel：LPG
Combustion air ratio：0.7 (CO concentration in stove：20 volume %)
Experiment condition and result are shown in table 8 and Fig. 5.
In Figure 5, with the ratio (quality %) less than 3mm of the 1st reduction product for transverse axis, with rotary furnace the (the 2nd Reduction furnace) in heating reduction treatment in the variable quantity (Δ %) of degree of metalization be the longitudinal axis, there is shown the result of table 8.By scheming 5 understand, when the ratio less than 3mm of the 1st reduction product is more than 75 mass %, the reduction reaction in rotary furnace becomes Without.
Embodiment 6
By melting furnace dust (powdery raw iron oxide material inferior) and coal mix and carry out it is Briquetting and obtain blocking thing (with Quality % is counted, metal Fe：1%th, FeO：38%th, Fe2O3：31%th, C：14%), the returning in 1250 DEG C of furnace temperature by the blocking thing Turn after being reduced in hearth reducing furnace (the 1st stage), be classified in advance by some benchmark particle diameter, it is small will only to sieve low-grades loading Essence reduction (the 2nd stage) is implemented in type rotary furnace (the 2nd stage).
Smart reducing condition is as follows.
Rotary furnace：300 × length of internal diameter 3400mm
The rotating speed of rotary furnace：3.2rpm
The furnace temperature of rotary furnace：1150℃
Burner fuel：LPG
Combustion air ratio：0.7 (CO concentration in stove：20 volume %)
Experiment condition and result are shown in table 9 and Fig. 6.
It is that the 1st reduction product is not carried out into classification in advance just to carry out its total amount with rotary furnace in level 7-1 Result in the case of reduction.In this case, the treating capacity total amount in the rotary kiln bed reduction furnace in the 1st stage (100%, 20.0t/h) carries out smart reduction with rotary furnace.As a result, the 2nd reduction product after being handled with rotary furnace is (in water In quasi- 7-1, it turns into product reduction iron) degree of metalization and the 1st reduction product degree of metalization residual quantity (hereinafter referred to as Δ degree of metalization.) it is 7.9%.
In level 7-2, the 1st reduction product discharged from rotary kiln bed reduction furnace is entered by benchmark particle diameter 16mm Go and be classified, lower part of screen point is only subjected to smart reduction with rotary furnace, pass through the bypass of sieve upper part, most both mix and shape at last Into product reduction iron.
Relative to the 1st reduction total treating capacity of product, the mass ratio for sieving low-grades is 63%, with total amount is handled Situation compare, be shown to minimize the specification of equipment of the rotary furnace formula reduction furnace in the 2nd stage to about sixty percent.Finally Δ degree of metalization be 7.6%, turn into compared with level 7-1 Δ degree of metalization 7.9% and the rising of percent reduction in no way inferior Amount.
In level 7-3, classification benchmark particle diameter is set to 12mm, in the same manner as level 7-2, low-grades rotary furnace will be sieved Smart reduction is carried out, is then mixed with having carried out the sieve top grade of bypass processing, forms product reduction iron.In this case, relative to The 1 reduction total treating capacity of product, the mass ratio for sieving low-grades are 48%, it is known that can be by the size small of rotary furnace to about Half.Final Δ degree of metalization is also 7.3%, compared with level 7-1, level 7-2, is able to maintain that phase same level Essence also commercial weight.
In level 7-4, classification benchmark particle diameter is set to be reduced to 4mm.Now, always handled relative to the 1st reduction product Amount, the mass ratio of lower part of screen point is only 16%, compared with can speculating the situation with total amount is handled, can make revolution The scale of stove significantly reduces.
But in this case, Δ degree of metalization is 2.2%, compared with not implementing the level 7-1 of classification processing in advance, most The ascensional range of whole degree of metalization significantly diminishes.It is considered that because, benchmark particle diameter as low as 4mm is classified, therefore under sieve The partial quality ratio less than 3mm reaches 73.0% unexpectedly, hampers the reason for the progress that the essence in rotary furnace reduces.
It is classified under the sieve for the result that Fig. 6 represents in each level of the present embodiment, implements the 1st reduction product classification Ratio (quality %), the dependency relation with the degree of metalization (%) of final product reduction iron.Furthermore it is not classified and is gone back the 1st The total amount of former product has carried out the degree of metalization 81.4 of the product reduction iron of the situation of smart reduction with rotary furnace formula reduction furnace (%), the opening position that ratio 100% is classified under sieve are shown.
As can be seen from Figure 6, as long as setting classification benchmark particle diameter is to cause by classification the sieve low-grades that generate relative to the 1st The quality percentage of reduction product total amount is changed into more than 50%.
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Utilization possibility in industry
The present invention can utilize in ironmaking industry.The ironmaking powder that will be discharged by using the present invention in ironmaking processes Contained iron oxide carries out reduction treatment and forms metallic iron in dirt, can be used again as refining raw material for iron.

Claims (5)

1. a kind of manufacture method of reduced iron, the reduction treatment in continuous two stages is carried out to blocking thing, the blocking thing is By the raw material containing iron oxide and reducing material mix and carry out it is Briquetting obtained from, the manufacture method is characterised by,
(i) rotary kiln bed reduction furnace is used in the 1st reduction treatment, then,
(ii) rotary furnace formula or vertical reduction furnace are used in the 2nd reduction treatment,
In the 2nd reduction treatment, the concentration of the CO gases in reducing atmosphere is below the volume % of more than 10 volume % 85,
By the generated in the 1st reduction treatment the 1st reduction product classification so that the reduction product under classifying screen only contains There is the reduction product that the particle diameter below 75 mass % is less than 3mm, stayed in by the 2nd reduction product and in the classification on sieve The 1st reduction product mixing, it is described 2nd reduction product be under the classifying screen reduction product carry out the described 2nd Obtained from reduction treatment.
2. the manufacture method of reduced iron according to claim 1, it is characterised in that
The reduction product the i.e. the 1st that is generated in the 1st reduction treatment reduce the degree of metalization of product for 65 mass % with Upper below 90 mass %.
3. the manufacture method of reduced iron according to claim 1 or 2, it is characterised in that make in the 2nd reduction treatment In the case of the 1st reduction product is handled with rotary furnace formula reduction furnace, the atmosphere temperature in the rotary furnace formula reduction furnace More than 1100 DEG C and for less than 1200 DEG C.
4. the manufacture method of reduced iron according to claim 1 or 2, it is characterised in that the raw material containing iron oxide It is including at least melting furnace dust, electric furnace dust, mill scale, pickling and the raw material for neutralizing any of sludge.
5. a kind of manufacturing equipment of reduced iron, it is the reduction iron for being reduced the blocking thing of raw material using continuous two reduction furnaces Equipment, the blocking thing of raw material be by the raw material containing iron oxide and reducing material mix and carry out it is Briquetting obtained from, should Manufacturing equipment is characterised by possessing：
(a) the rotary kiln bed reduction furnace as the 1st reduction furnace, it is used for the blocking thing reduction of the raw material；With
(b) the rotary furnace formula as the 2nd reduction furnace or vertical reduction furnace, it is used to generate in the 1st reduction furnace Reduction product is that the 1st reduction product further reduces
And it is also equipped with：
By the classifying equipoment of the described 1st reduction product classification；With
The 1st reduction product being in the classifying equipoment under sieve is fitted into the 2nd reduction furnace, and will be described the What the 2nd reduction product generated in 2 reduction furnaces and the 1st reduction product stayed in the classifying equipoment on sieve mixed sets It is standby, use rotary furnace formula reduction furnace as the 2nd reduction furnace.
CN201580002585.3A 2014-03-11 2015-03-10 The manufacture method and manufacturing equipment of reduced iron Active CN105723002B (en)

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