CN101035920A - Production of ferro-alloys - Google Patents

Abstract

A method for producing a ferro-alloy in an electric arc furnace is disclosed. The method comprises the step of charging the furnace with an un-agglomerated carbon-containing polymer such that the polymer functions as a slag foaming agent.

Description

The production of iron alloy

Technical field

The invention discloses a kind of use new additive agent and in electric arc furnace (EAF), produce the method for iron alloy (for example steel).In its main function, described new additive agent plays slag foaming agent, reductive agent.Yet described additive can act as a fuel and/or in addition as recarburizer.

Background technology

In 50 years, plastic industry has experienced huge development in the past, makes plastic material and product be absolutely necessary to society now.Plastics-production has reached annual about 1,500 ten thousand tons in the country of for example Japan, this causes annual about 900 ten thousand tons relevant refuse, and wherein 50% is relevant with municipal solid waste.

The problem of process in plastics is more and more, and the small portion that only accounts for salvage material is used in plastics recirculation in the world, and remaining passes through landfill or burning disposal in incinerator.Plastic material is difficult for degraded and oozes out poisonous element at landfill yard, and traditional burning simultaneously produces for example two  compounds of noxious emission usually.。

In the world wide, Iron And Steel Industry is in the face of minimizing their pressure to the influence of environment by improving the efficiency and the utilization of resources.For example, done the carbon intensity that concrete effort reduces blast furnace.A strategy of blast furnace energy management comprises the consumption that reduces fuel or coke.Fuel as an alternative, CO is reduced in the air port that has proposed plastics are injected blast furnace ₂Discharging, this be because the ignition energy of plastics the powdered coal with common injection is the same high at least, and the ratio of its hydrogen and carbon is higher, produces the less CO as products of combustion ₂

It is known adding plastics in the steel melting furnace of other type, comprises electric arc furnace (EAF).For example, US5,554,207 disclose a kind of method, and wherein the useless dust of EAF combines with plastic waste to form solid, and it is added among the EAF then.Similarly, JP2004-052002 discloses a kind of method, and wherein plastic waste and steel-making dust are mediated (knedaded) and formed soft solid together, add among the EAF then.The none document relates to the adding additive and promotes slag foaming.

Summary of the invention

In a first aspect of the present invention, provide in electric arc furnace the method for producing iron alloy, it comprise with caking not contain the feed step of described stove of carbon polymer, make described polymkeric substance play the slag foaming agent.

Term " not caking contain carbon polymer " comprises fine and coarse micronize and granulating polymkeric substance, and the polymkeric substance that forms with useless dust of EAF or steel-making dust of eliminating.This caking solid does not play the slag foaming agent.

Expection in advance not, the containing carbon polymer and can be used for causing slag foaming of caking not in electric arc furnace.In electric arc furnace, the slag foaming of increase covers melt metal better and better keeps heat (promptly adiabatic), causes the electric consumption among the EAF to reduce significantly like this.

In producing the iron alloy method, not the containing carbon polymer reductive agent can be played in addition of caking, play fuel and/or recarburizer.Described subsequently polymkeric substance can be so that the metal oxide reduction that produces during that exist in the stove charging and/or the metal processing; And/or the source that acts as a fuel; And/or increase the amount of the carbon that carbon in the final iron alloy exists with iron as recarburizer.For example, the main fuel source is in electric arc furnace.

Therefore, plastic waste can improve energy efficiency (promptly by utilize less), and can reduce for example consumption (and therefore reducing cost) of coke and coal of traditional carbon source.Plastic waste can also replace or reduce the use of expensive recarburizer, for example hard coal and graphite.

When term " iron alloy " when being used for this paper, it comprises iron-carbon alloy (comprising steel) and other the iron-carbon and/or the iron-Ji alloy of wide region, comprises ferrochrome, ferrochrome silicon, ferromanganese, ferro-silico-manganese, ferrosilicon, magnesium ferrosilicon, molybdenum-iron, ferronickel, ferrotianium, ferrophosphorus, ferrotungsten, vanadium iron, ferrozirconium etc.

The carbon polymer that contains that typically will not lump is feeded in stove, makes its partial combustion and produce carbonaceous residues at least.Because its burning, polymkeric substance acts as a fuel.Carbonaceous residues can oxidation to cause slag foaming.Residue can play reductive agent or recarburizer in addition.Therefore, the not caking of feeding in stove contains the carbon polymer effect of slag foaming precursor usually.It can also play recarburizer precursor or reductive agent precursor.

Although the containing carbon polymer and can comprise the unique additive that is charged in the stove of caking not, in typical embodiment, Jie Kuai the carbon polymer that contains is not feeded in stove with other carbon source.This other carbon source can be burnt to act as a fuel.It can also help slag foaming, and can play reductive agent or recarburizer.Other carbon source can be coal, coke, carbon Jiao (carbon char), charcoal or graphite.

As embodiment, the carbon polymer that contains that does not lump approximately can be feeded in stove with 1: 1 weight ratio with other carbon source, although this ratio can change according to stove.

In the typical method that changes, the described carbon polymer that contains is a plastic waste.Plastic waste feeded provides the mode of effective treatment of waste plastics in stove, otherwise it causes environmental problem.

Typically, contain carbon polymer and only comprise C, H and optional O atom.Although can there be other element (for example N, S, P, Si, halogen etc.) in the polymkeric substance, these other elements can disturb the production of iron alloy and/or produce impurity, pollutent, obnoxious flavour etc.Therefore, the selection by wisdom contains carbon polymer, can avoid obnoxious flavour and other formation disadvantageous and harmful product.A kind of suitable plastics are polyethylene, but also can use other plastics for example polypropylene, polystyrene, polyhutadiene vinylbenzene, ABS etc., even can use for example resol of the very difficult plastics of handling again.

Typically, it is the polymer beads form that not the luming in stove of feeding contains carbon polymer, and exemplary particles is of a size of 100 μ m or littler.

Though the typical iron alloy of producing is a steel, the production of other iron alloy (as mentioned above) also can be used not lump and contain the charging of carbon polymer.

In a second aspect of the present invention, provide in the production that caking not contains carbon polymer iron alloy in electric arc furnace purposes as the slag foaming agent.

Usually, the caking typical use that contains carbon polymer is the production of the iron alloy that the method by first aspect realizes.

In a third aspect of the present invention, provide the method for producing iron alloy in electric arc furnace, described method comprises the following steps:

-iron alloy the raw material of in stove, packing into;

-raw material in stove is heated to molten state and forms slag on the melt surface of alloy/raw material; With

The not caking of-slag foaming agent effect of in stove, having packed into contain carbon polymer.

Typically, the carbon polymer that contains of packing into and not luming to burn and to discharge heat energy to fused alloy/raw material, produces the material that makes slag foaming in stove.

Randomly, described material except making slag foaming, can:

-cause that the chemical reduction of various metal oxides in the slag is to produce iron alloy;

-to the iron that obtains and the alloy carburetting again of carbon.

Caking does not contain carbon polymer and can pack into other reagent.Other reagent can be other carbon source that defines in the first aspect.

Caking does not contain carbon polymer and can also pack in the stove with raw material.For example, charging feedstock and when containing carbon polymer in stove, stove can be heated (promptly with successive furnace operating pattern).

The typical method of the third aspect is in addition as defined in the first aspect.

The inventor infers that also the carbon polymer that contains of caking usually can be as the fuel in the reheating furnace.

Therefore, in a fourth aspect of the present invention, provide the method for operation reheating furnace, it comprises and contains the feed step of described stove to act as a fuel of carbon polymer with caking not.

Typically, described reheating furnace is operated under the temperature of burning carbonaceous polymkeric substance being enough to, and typical temperature is greater than 1000 ℃.

In addition, not caking contain carbon polymer can with particle form and optional with other fuel for example Sweet natural gas feed in stove.

In a fifth aspect of the present invention, provide a kind of system, it determines to contain the recyclability of carbon polymer in the stove of the production iron alloy that uses carbon raw material.Described system comprises the following steps:

-derive the parameter value of given polymkeric substance, described parameter value has reflected the slag foaming ability of polymkeric substance;

-described parameter and one or more parameter values of being led the place by one or more other polymkeric substance are compared;

-form scope or scale by those parameter values.

Described parameter can be the life-span of the height and/or the foamed slag of foamed slag.

Description of drawings

Although other embodiment may fall into the production method of the iron alloy that summary of the invention defines, referring now to accompanying drawing the specific embodiments of present method is only described by way of example, in the accompanying drawing:

Fig. 1 illustrates the level pipe resistance furnace schematic representation of apparatus of the method for dripping admittedly (sessile drop approach), as described in example 1 above;

Each illustrates a drip melt slag Fig. 2 A-2F, and the slag foaming of graphite/slag system and time correlation is shown in turn, and it utilizes the level pipe resistance furnace device of Fig. 1;

Each illustrates a drip melt slag Fig. 3 A-3F, and the slag foaming of coke/slag system and time correlation is shown in turn, and it utilizes the level pipe resistance furnace device of Fig. 1;

Fig. 4 A-4C illustrates a drip melt slag of graphite, graphite/plastics and coke respectively, and each has the slag system, and utilizes the level pipe resistance furnace device of Fig. 1;

Fig. 5 shows drop tube furnace (drop tube furnace) schematic representation of apparatus, as described in example 4 above;

Fig. 6 shows the XRD spectra of 50% plastics and the 50% graphite mixture carbonaceous residues after reacting in drop tube furnace, as described in example 5 above;

Fig. 7 shows the ccd image of the slag foaming that is caused by various carbonaceous materials, as described in example 5 above;

Fig. 8 shows the IR result who reacts between graphite base and the industrial slag, as described in example 5 above;

Fig. 9 shows the IR result who reacts between 50% plastics and 50% graphite base and the industrial slag, as describing among the embodiment 5;

The IR result that Figure 10 shows at the bottom of the coke-based and reacts between the industrial slag is as describing among the embodiment 5;

Figure 11 shows the synoptic diagram of induction (carbon dissolution) stove, as described in example 7 above;

Figure 12 indicates in the induction furnace will go out Figure 11 carbon dissolution % and time relation in the molten pig alloy, as described in example 7 above;

Figure 13 A and B illustrate a coke/slag (above-listed) and coke/HDPE plastics/slag (following) over time, utilize the level pipe resistance furnace device of Fig. 1;

Figure 14 indicates coke and coke and the plastic hybrid efficiency of combustion η in the time of 1200 ℃, as described in example 9 above;

The ccd image of 70% coke-30% plastic residues when Figure 15 the shows 1550 ℃/slag system and slag foaming time correlation, as described in example 10 above;

Figure 16 indicates CO and CO ₂Gas produces and time relation, as described in example 10 above;

Figure 17 indicates the mole number of the oxygen of removing during slag and coke and 30% plastics+70% coke mixture interact, as describing among the embodiment 10; With

The V of coke and 30% plastics+70% coke mixture when Figure 18 shows 1550 ℃ _t/ V _oFigure, as described in example 10 above.

Embodiment

During the further investigation to the production of EAF steel, notice that the chemical reaction between solute carbon/solid carbon and the slag causes the slag foaming process again.Because ferric oxide is produced by carbon reduction in the slag CO gas and because the oxidation generation slag foaming of carbon.Notice that slag foaming depends on the carbon raw material properties consumingly, and properties of materials control slag foaming phenomenon during high temperature.

Be further noted that foamed slag has covered metal bath and kept heat and shielded arc, this causes significant energy saving (promptly reducing electric consumption).Notice that production is crucial to constant slag foaming level to effective EAF steel.

In wonderful development, supposing that not caking contains carbon polymer (for example plastic waste, particle form) typically and can be introduced in the EAF Iron and Steel Production.Supposition is under the high temperature that is used for the EAF Iron and Steel Production, and in a single day plastic waste is introduced in the stove and will be burnt (therefore acting as a fuel) and generation carbonaceous residues product.Subsequently, suppose to contain in the production that carbon polymer can also be introduced into other iron alloy, and also produce the carbonaceous residues product.

Observe, the carbonaceous residues product can cause the slag foaming in the production of EAF steel subsequently, and can randomly play reductive agent (for example in the production of other iron alloy), randomly also can play recarburizer.

Duration of test supposes that chemical constitution, structure and key network (bondnetwork) in the original plastic determined the performance of carbonaceous residues.In addition, notice from the carbon dissolution kinetics of given plastics and be dissolved in speed in the liquid steel based on carbonaceous residues.Suppose the orderly carbon of relative height in the plastics (for example with coke in carbon ratio) can cause the increase of carbon dissolution in the liquid steel.

The structural characterization of carbonaceous residues is undertaken by plastics-graphite mixture being introduced in the drop tube furnace (drop-tube furnace) (operational condition that may experience among the simulation EAF), cause blistered those carbonaceous residues of molten slag among the EAF subsequently to observe, and determine that those carbonaceous residues can have reducing power and/or the enhanced carbon dissolution in the molten pig alloy.Described in the result of structural characterization such as the following embodiment 5.

In other iron alloy production, notice, use various carbon containing reducing materials.The carbonaceous reductive agent material of known packets is coke, coal and charcoal and by the biological carbon of dissimilar wooden charcoal forms of producing for example.Notice that once more the material behavior of these carbonaceous materials plays significant effect with being reflected in the control reductive agent performance.

Therefore wherein main experiment is considered to comprise, the gasification of research reductive agent, and carbon dissolution is gone into molten metal and solid carbon and is directly reduced slag.

Be also noted that in the production that is formed on the iron alloy except that steel of slag be common.Manganese and chromium all are reduced at solid and liquid state.Think that MnO reductive dominant mechanism is that MnO is dissolved in the slag, reduce from slag by solid carbon or the carbon that is dissolved in the liquid metal subsequently.Similarly, notice, very important by the chromite in the dissolved carbon reduction molten slag in the Fe-Cr melt for the production of ferrochrome.Carbon and comprise being reflected between the liquid slag of dissolved ore (oxide compound of chromium, manganese) and play crucial effects in the reduction process.Therefore supposition also can be as the reductive agent in other alloy production when needing (and as the slag foaming agent) from the carbonaceous residues of plastic waste.

Embodiment

The non-limiting example of producing the iron alloy method is provided now.

Embodiment 1

In order to study slag foaming, at first in dripping the level pipe resistance furnace of method admittedly, laboratory scale utilization studies the interaction of slag/carbon.Fig. 1 illustrates the synoptic diagram of experimental installation.The weight of used slag is～0.20g.At first, sample is placed on the specimen holder, it can be pushed into heating region center in the stove by means of stainless steel.

The cold-zone that the combination of slag/carbon is remained on stove is up to obtaining desired temperatures (1550 ℃) and in the hot-zone of stove balance.Described being combined under the research desired temperatures inserted the hot-zone.This has got rid of may and may influence any reaction for the treatment of in the phenomenon of temperature studies interested in the low temperature generation.During whole test, use the argon purge boiler tube.With mass flowmeter control argon gas flow velocity.

Utilize the foaming behavior of dripping technical study slag/carbon system admittedly of strict control and vision monitoring.Use high quality, the high resolving power charge-coupled device (CCD) camera of equipment IRIS camera lens to catch the interior real-time in-situ phenomenon of stove.The output of camera is imported into video recorder (VCR) and TV (TV) watch-dog writes down in time whole process.This can be so that utilize frame grabber will show that from video-tape concrete picture catching that slag contacts with carbonaceous material is in computer in time.The time of in described system, utilizing time-time date generator to come procedure for displaying to continue.The computer software of use particular design is put into practice based on fitting of a curve and is determined volume from the image that captures.In order to understand reaction response kinetics better, the most applications document image reaches 2 hours most.

Slag is composed as follows: CaO 30.48%, and MgO 11.72%, SiO ₂13.34%, Al ₂O ₃5.24%, Fe ₂O ₃33.33%, MnO 5.24%.

At first graphite and coke are carried out slag foaming research.Plastics carried out slag foaming research thereafter.

Result and discussion

Graphite/slag system: the PRELIMINARY RESULTS that slag foaming in graphite/slag system is shown among Fig. 2 A-2F in time.

Graphite is produced slag to steel and is demonstrated good slag foaming characteristic.In Fig. 2 A, during second, show that the slag powder has just begun fusing at T=13.In Fig. 2 B, show drop during second just in moulding at T=47, in Fig. 2 C, show during second at T=57 to be completed into.Droplet size begins to become big then, in Fig. 2 D, observes obviously bigger drop when T=1 divides 7 seconds, in Fig. 2 E, shows when T=1 divides 22 seconds slag foaming takes place.In Fig. 2 F, droplet breaks a little when T=1 divides 57 seconds, shows that some gaseous product partly escape.Therefore, find that the slag foaming in graphite/slag system is very fast and extensive.

Coke/slag system: the PRELIMINARY RESULTS that slag foaming in coke/slag system is shown in Fig. 3 A-3F in time.

Coke is produced slag to steel and is shown bubbling character not too reliably.In Fig. 3 A, T=9 shows that the slag powder has just begun fusing during second.In Fig. 3 B, drop begins moulding when T=1 divides 20 seconds.In Fig. 3 C-3F, shown to divide and divided 37 seconds images in the scope to T=21 in 15 seconds from T=2.Through this period, drop is completed into.Four drops have shown very little fluctuation on size and volume, show quite low-level slag foaming in coke/slag system.Therefore the speed of the speed ratio graphite/slag system of slag foaming is slow in coke/slag system.

Carbon dissolution research discloses, and the constant of dissolution rate of coke is less than graphite.The slag foaming behavior of these two kinds of carbon types is quite different, much bigger than coke/slag system of the speed of slag foaming and scope in graphite/slag system.Therefore, suppose that carbon dissolution speed and slag become the relation between the bubble.

Embodiment 2

Analyze factory's service data of operation EAF and learn, improve coke injection level and cause oxygen consumption to increase, although they do not produce the catabiotic clear and definite pattern of any charging steel per ton.

EAF operates in its operation and uses two kinds of multi-form carbon.With containing～coke of 90%C, use several tons of band irons that contain 4%C.During the band iron fusing, the carbon that exists in the band iron dissolves, and the carbon that exists in the coke exists with solid state.

Observe, the form of carbon (solute or solid carbon) has remarkably influenced to average energy consumption/ton steel.Along with the increase (the solute carbon that is equivalent to higher level) of band iron charge amount, energy expenditure obviously reduces.Explain this trend according to the carbonaceous material role, and show that the increase of slag foaming causes the energy expenditure of charging steel per ton to reduce.Therefore, to get efficient much higher for the corresponding coke of efficiency ratio of finding band iron carbon in the production of EAF steel.

The inventor notices:

1. carbon dissolution is in the very big character that depends on carbonaceous material consumingly of kinetics of liquid iron.For example, the constant of dissolution rate of coke is less than graphite.

2. the result of the graphite/slag of embodiment 1 and coke/slag system shows, the slag foaming speed of graphite and scope are much larger than coke.

3. expection is quite different with the carbon/slag interaction dynamics for coke for solute carbon, and this causes their slag foaming behavior to alter a great deal.

These results show that the suitable selection of carbonaceous material has vital role to slag foaming, and the energy efficiency of therefore EAF being operated plays an important role.Described result also makes the contriver infer, can will contain carbon polymer add EAF, the partial combustion and produce the carbonaceous material residue of acting as a fuel, it can cause slag foaming and/or metal oxide reduction and/or recarburization again.

Embodiment 3

Inventor's test now adds plastic waste to the EAF process and replaces at least some traditional carbon sources (for example coke).Following starting material are combined the simulation charging in the starting material of EAF.

Starting material

Use following carbonaceous material, plastics and slag to carry out the slag foaming comparative experiments.

Carbonaceous material: graphite; Coke; The residue (Fig. 6 provides the XRD spectra of this residue) that graphite and plastic hybrid (1: 1) produce.1: 1 ratio can change according to stove.

Plastic material: obtain the main component that linear low density polyethylene (LLDPE) is represented plastic waste material.The particle size of used polyethylene specimen is less than 100 microns.

Slag: the slag composition (%wt) below the preparation: 30.48% CaO; 11.72% MgO; 13.34% SiO ₂5.24% Al ₂O ₃33.33% Fe ₂O ₃5.24% MnO.

By 2.2 * 10 ⁸Hydraulic pressure under the Pa pressure prepares the matrix of carbonate material powder.Graphite and coke powder use with the form of their supplies.The preparation method of graphite and plastic hybrid is recorded among the embodiment 4.

By being heated to 1650 ℃ with the uniform mixture of the oxide components of above-mentioned ratio of mixture, then after melting about 30 minutes fully in copper mold the casting melt prepare slag.

Instrument

Use the horizontal stove of Fig. 1 to consolidate an experiment.The pottery boiler tube is of a size of internal diameter Φ 50mm, length 1000mm.Insert the specimen holder that aluminum oxide or graphite are made by bell.Described instrument makes sample remain on the cold-zone of stove when stove is heated to preferred temperature, and preferred temperature typically is 1550 ℃ in this embodiment.

Experimental procedure

In order to study slag foaming, at first in the level pipe resistance furnace, study slag/carbon and interact.The cool region that the combination of slag/carbon remains on stove is to obtaining desired temperatures (1550 ℃) and adding district's balance at stove.Subsequently the described desired temperatures that is combined in is inserted the hot-zone.This step has been got rid of and may any reaction in the phenomenon of temperature studies interested have been taken place and may influence at low temperature.During entire test, use the argon purge boiler tube.

Utilize the technology of dripping admittedly of strict control and vision monitoring to study the foaming behavior of slag/carbon system once more.The CCD camera that reuses equipment IRIS camera lens is caught the interior real-time in-situ phenomenon of stove.The output of camera is imported into video recorder (VCR) once more and TV (TV) watch-dog writes down whole process in time.Utilize frame grabber catch to show that from video-tape image that slag contacts with carbonaceous material is in computer in time.The time of utilizing time-time date generator to come procedure for displaying to continue once more.The software that uses a computer is put into practice based on fitting of a curve and is determined volume from the image that captures.

(about 0.20g) is placed on the carbonaceous material matrix that remains on the specimen holder with the slag powder.In case reach the furnace temperature of expectation, just specimen holder is pushed the hot-zone from the cold-zone of stove, begin experiment.By the whole process of CCD phase machine monitoring and use video recording.Further analysis image comes the calculation sample volume.In the whole experiment, with the flow velocity purging rare gas element argon gas of 1l/min.In order to obtain to be used for the CO and the CO of response estimator speed ₂Content is discharged gas by the IR analyser.

Experimental result

Carrying out this tests and studies by ferric oxide in the slag and carbonaceous material: the slag foaming behavior that the reaction between graphite, graphite/plastic residues mixture and the coke causes.Fig. 4 A-4C shows typical image.

The reaction of observing between graphite and the slag produces intensive slag foaming.As being clearly shown that the drop volume maximum of foaming slag among Fig. 4 A.

Between the reaction period of 50% graphite/50% plastic hybrid, develop from the slag droplet and bubble.The appearance of the slag foaming phenomenon under graphite/plastic hybrid situation is on the high temperature visual image basis that is based upon shown in Fig. 4 B and is based upon on the basis of discharging CO generation in the gas, shows the reduction of ferric oxide.These expression plastics can add the burning that acts as a fuel among the EAF, and carbonaceous residues can produce that slag foaming and/or metal oxide reduce and/or recarburization again.

Embodiment 4

The preparation method of graphite/plastic hybrid

Utilize drop tube furnace (DTF) to carry out the High Temperature Gas phase reaction of plastics-graphite adulterant.Schematically show drop tube furnace among Fig. 5.

Each test of carrying out in DTF is finished in the time of 1200 ℃, in case stove reaches this service temperature, just oxygen and nitrogen is imported in the stove with the flow velocity of expecting.At these experimental session utilizations automatic flow rate control instrument pilot-gas flow velocity and composition.Each duration of test is cooling water circulation by the stove injector, so as to prevent overheated and in the stove reaction zone fuel of oxygen and injection react before interacting.Collector also is used for keeping the unburn charcoal that each experimental session produces.

Utilize the dry-matter feeder plastics-graphite adulterant to be introduced in the experimental reactor by the water-cooled feed conduit.The mixture of use oxygen and oxide gas transports plastics and the graphite solid reactant enters reaction zone.Experimental detail is as follows:

Temperature (℃)	1200
		Total gas flow rate (L/min)	1.0
Feeding rate (g/hr)	10.0
		The particle residence time (second)	～1-2
Gas purity (%)	N 2＝99.5 O 2＝99.0
		Gas composition	24％O 2, surplus
Graphite granule size (μ m)	＜100μm
		Plastic grain size (μ m)	＜100μm

This experiment shows that under the operational condition of those in simulation EAF, plastics can be feeded in EAF, the burning that acts as a fuel, and formation causes slag foaming, metal oxide reduction and the molten pig carbonaceous residues of carburetting again.

Embodiment 5

Follow the EAF slag foaming phenomenon of the reaction between slag and the carbonaceous material

Experimentize and study actual EAF slag sample, more particularly, become the bubble phenomenon at slag under the inert argon atmosphere and the slag that contains between reaction period between the carbon.Described slag consists of 27.0% CaO; 40.3% FeO; 7.9% Al ₂O ₃8.8% MgO; 10.9% SiO ₂And 4.8%MnO.The basicity of described slag is 2.5 (%CaO/%SiO ₂).Select three kinds of carbonaceous materials to experimentize.They are pure graphite; Graphite and plastics are with the carbonaceous residues of 1: 1 ratio blended mixture; With industrial coke.1: 1 ratio can change according to different EAF.About 0.075g slag is used in each test.Temperature is set at 1550 ℃.

50% plastics are shown Fig. 6 and 50% graphite mixture reacts the XRD spectra of the residue of generation afterwards in drop tube furnace (DTF).Can be clear that the peak of plastics and graphite.

Utilize CCD cameras record slag/carbon foaming phenomenon.The typical image that Fig. 7 shows in the time of about 200 seconds and the foaming slag of various carbon containing substrate reactions drips.With the situation of graphite-based qualitative response under slag foaming the most violent.Although the reaction between the mixture of slag and graphite and plastics and graphite is so inviolent, the result shows that plastics can be used as the slag foaming agent and the reductive agent of EAF slag.

Utilize the IR analyser to analyze DTF and discharge CO and CO in the gas ₂Content.The results are shown among following Fig. 8,9 and 10.Under the situation of graphite matrix, discharge CO and CO in the gas ₂Content is only less times greater than other situation.This means that all three kinds of carbonaceous materials have all occurred because the gas of iron oxide reduction generates and all three kinds of carbonaceous materials all help slag foaming.

In addition, the result of embodiment 5 is consistent with the result of the embodiment of front, although the composition difference between industrial slag and the prepared in laboratory slag.

Embodiment 6

The efficiency of combustion of research plastic waste is checked the suitability of plastic waste as the fuel of EAF or other non-air blast type stove.The drop tube furnace (DTF) that uses Fig. 5 with 4 kinds of identical conditions of embodiment under assess efficiency of combustion.Before each check is carried out and afterwards (promptly after each sample is by DTF) determines the %C in the sample.Use LECO carbon content analyser to determine carbon content.

Each sample comprises the powdered plastic waste with powdered coke blended change level, begins to rise to the 50wt% plastics by the 0wt% plastics.Result's form kind is below listed:

Plastics wt% and coke	Before the C wt%	After the C wt%	Efficiency of combustion (%)
				0	80.43	80.39	0.25
20	82.376	80.921	9.26
				30	82.79	81.736	6.97
40	83.723	82.27	9.79
				50	84.372	83.145	8.63

Top form is listed the terrible efficiency of combustion that arrives (last hurdle), has also listed thick wt%C and has analyzed.The reduction of wt%C is the result that carbon reaction (burning) generates carbon monoxide and carbon dioxide.

The result shows that the efficiency of combustion of coke is very low, but when coke and plastic waste mixing, efficiency of combustion improves.In addition, the residue that stays after the burning participates in other reaction in EAF or other the non-air blast type stove subsequently.

Embodiment 7

In order to study plastic waste function as recarburizer in iron alloy is produced, the carbon dissolution of research carbonaceous residues in the laboratory scale induction furnace of indicative icon in as Figure 11.

The temperature of stove is controlled at the molten iron bath temperature (simulation EAF service temperature) that reaches 1550 ℃.In this, cooling water circulation by " chuck " heat converter structure in whole process around stove, to prevent overheated and to keep common constant to bathe temperature.On molten bath, pass through N ₂Inlet is created nitrogen atmosphere.

In stove, described powder feed is on molten iron bath with the direct charging of the powder of plastic waste.This plastics burning is to produce carbonaceous residues, and this residue can play recarburizer.As selection, the plastic waste from the drop tube furnace of for example Fig. 5 can be imported on the molten iron bath.

Carburizing agent cladding process (carburiser cover method) is the standard method of research carbon dissolution.In this, in fact carbonaceous material is positioned at the metal bath top and forms the carburizing agent coverture.This is because plastics waste material is fed in the metal bath top in experimentation.Measure the thermopair of bathing temperature and take out metal sample, extend through the carburizing agent coverture progressively to measure the quartzy stopple coupon of carbon dissolution in time.Use the carbon content of the metal sample of LECO carbon content analyser analysis extraction subsequently.

Figure 12 illustrates the result of carbon dissolution.As can be seen from Figure 12, the dissolved carbon content of initial (time=0) described bath is 1.67 weight %.Add plastic residues then, the dissolved carbon content increases to 2.97 weight %, maintains an equal level on 3% level then.In time=25 timesharing, other plastic residues is added in the balneation, the dissolved carbon content increases to 3.89% in the T=30 timesharing.

This experimental results show that plastic residues can be used as effective recarburizer, by progressively introducing the progressively increase that plastic residues can realize the dissolved carbon level.In EAF or other non-air blast type stove, the residue that is used for carburetting more typically produces as follows: plastic waste self is introduced in the stove, make its burning produce carbonaceous residues, impel it to sneak into bath of molten metal and set apart subsequently to increase the level of carbon content to expectation.Plastic waste can replace more expensive recarburizer for example hard coal and graphite.

Embodiment 9

The efficiency of combustion of coke/plastic hybrid

The mixture of coke and it and plastics (the highest 50wt%) 1200 ℃ containing 20%O ₂Oxidizing atmosphere under DTF in burn.Feeding rate is about 0.0278g/s.Collect carbonaceous residues and measure its carbon content.Suppose can ignore ash loss during the burning in DTF the following calculating of efficiency of combustion η:

$\mathrm{\η}=(1-\frac{A_0}{A_i}\frac{C_i}{C_0})\×100\%$

A wherein ₀And A _iBe the ash oontent before and after the burning, C ₀And C _iRepresent the carbon content before and after the burning in DTF respectively.The experimental result of the efficiency of combustion of coke/plastic hybrid shown in Figure 14.Because the variation of efficiency of combustion is bigger, use logarithmic scale along the y-axle.

The integral combustion efficient of observing coke/plastic hybrid in this embodiment is near 40 times of the efficiency of combustion of coke separately, and promptly coke-plastic hybrid is 0.25 for～10 coke.Coke/plastic hybrid than high burning efficiency to a certain extent owing to a large amount of releases of volatile matter during the plastics burnings.Although coke and plastic hybrid have the efficiency of combustion very higher than coke usually, clear and definite trend is not observed in the influence of mixture ratio.Yet, increase plastic fraction and do not observe the efficiency of combustion reduction.

Embodiment 10

The slag foaming of carbonaceous residues

The coke after will burning in DTF and the carbonaceous residues of plastic hybrid are at 9 tons/cm ²Load be pushed down into mould and as the matrix of slag foaming experiment.Reach after the preferred temperature, slag begins fusing, and the ferric oxide that exists in the slag begins to produce CO and CO with the carbon containing substrate reaction ₂Gas and metallic iron.CO and CO by the slag phase ₂The generation of gas causes slag foaming.Use CCD phase machine monitoring reaction process and be recorded in and be used for further image analysis in the DVD dish.Figure 15 has shown the typical image of the reaction between slag and 30% plastics+70% coke mixture.After the slag fusing, observe immediately from slag and emit bubble mutually.Because the generation of bubble and breaking, the slag droplet acutely rolls in matrix.After about 600 seconds, the slag droplet calms down gradually, and the gas of generation also significantly reduces.

Between the reaction period of slag and coke/plastics substrate, FeO in the slag and the reaction of the C in the matrix generate CO and CO ₂Gas.Utilize the concentration of these gases in the IR spectrometer measurement expellant gas mixture.

The typical CO and the CO that obtain shown in Figure 16 ₂Gas content.Can see CO and CO ₂Gas content sharply increases to maximum value, stablizes and reduces with the reaction times then in about 300 seconds.Detected CO in discharging gas ₂Gas is far fewer than CO.Utilize the standard gas equation, will be by discharging CO and the CO that gasometry obtains ₂Volume be converted to mole number.The mole number of the oxygen of removing as shown in figure 17, has reacted the kinetics of reduction reaction between slag and the carbonaceous material.

The result shows that slag is more faster than the reaction of corresponding and plastics-coke mixture with the reduction reaction of coke, causes the discharge gas of more volume.These gases cause slag foaming and change the volume of slag droplet.

Subsequently with V _t/ V _oMeasure the gas maintenance dose (Gas hold-up) in the slag droplet, V _tSlag drop volumes when being time t, V _oIt is initial volume.Figure 18 indicates the V of coke and 30% plastics+70% coke mixture _t/ V _oWith time relation.The result shows that compare with coke, 30% plastics+70% coke mixture has very higher slag foaming level.Under coke/plastic hybrid situation, it is very big that the size of droplet becomes, and compares with coke, and the very longer time is kept in this size increase.To a great extent, this may be because the speed of reaction between plastic hybrid and the slag quite slow (Figure 17) causes slow gas rate of discharge, therefore causes less bubble and keeps the longer time of bubbling.For coke, air bubble growth is rapid, and the gas volume of being escaped by the slag droplet is many.

The research of embodiment 9 and 10 STRENGTH ON COKE and coke/plastic hybrid scope is further illustrated in the feasibility of utilizing plastic waste in the EAF steel-making.Coke/plastic hybrid demonstrates the burning more most preferable than pure coke.The slag foaming characteristic of discovery coke/plastic hybrid is better than pure coke.The volume growth of slag droplet is bigger, and volume change keeps the longer time.The result also shows, can strengthen carbon burning with coke/plastic hybrid part coke for replacing.

Embodiment 11

In similar embodiment 3, describe with Fig. 4 in the illustrated experimentation, studied the bubbling character of coke/slag system and 50% coke/50% plastics/slag system.In this case, plastics are particle sizes less than 100 microns high density polyethylene(HDPE) (HDPE).Slag is similar to the slag of embodiment 5, and two kinds of systems are used 0.078 gram and 0.092 slag that restrains respectively.Test at different time, so slag weight is incomplete same.Yet this weight differential does not influence experimental result.

Figure 13 A and B illustrate the droplet formation behavior of two kinds of systems when 0,30,45,60,90,150,210 and 300 second timed interval side by side and compare.Can see the foaming characteristic ratio coke/slag system of coke/plastics/slag system rapider.

In other words, plastics for example HDPE also can provide enhanced slag foaming characteristic to EAF or other non-air blast type stove, and this shows that a lot of other plastics can provide similar enhanced performance.

Embodiment 12

Inventor imagination has also proposed an index, be used for indicating plastics iron alloy produce and in other non-air blast type stove as the suitability of utilizing again of combustible fuel.Described index is called the green color index (Green Index) (or " GIP " index) of plastics.The present invention goes into imagination, and described index can also relate to the recyclability of plastics in general sense, but still is called the GIP index at present.

Like this, can establishment of a mechanism, can recognize the recyclability of plastics by this public, for example iron alloy production as steel-making in.The inventor notices that the system of the evaluation plastic type of using does not provide any information about the plastics recyclability at present.Present system only provides the information (for example numeral 1 is represented PET etc.) about plastic type.

At last, the inventor infers that the GIP index can be set up by developing relevant GIPS index subsequently, the suitability that " S " representative and indication plastics are used to make steel.

Generally speaking, experiment also shows, the iron alloy production except steel for EAF, can be in stove with the charge of plastics of not luming, can be used as fuel combustion, the carbonaceous residues of slag foaming be can be formed for, and the reduction of metal oxide and the carburetting again of molten metal (for example iron) caused.

In addition, experiment points out that also for reheating furnace etc., the plastics that do not lump can be feeded in stove, for example as other fuel replenishing of Sweet natural gas for example, and the burning that still acts as a fuel at present.(greater than 1000 ℃) are used for for example especially true at the reheating furnace of iron and steel forming operation when high temperature.

Therefore, the invention provides the effective ways that utilize and consume a large amount of social plastic waste.

Although described many specific embodiments, should be appreciated that, produce the method for iron alloy and can implement with a lot of other forms.

Claims (26)

1. method of in electric arc furnace, producing iron alloy, it comprise with caking not contain the feed step of described stove of carbon polymer, make polymkeric substance play the slag foaming agent.

2. the process of claim 1 wherein the described not carbon polymer that contains of caking feeded in described stove, make its partial combustion and produce carbon containing combustionresidue at least, with the described residue of rear oxidation to cause slag foaming.

3. the method for claim 2, wherein said residue can also or play recarburizer as reductive agent.

Each method of 4 aforementioned claims wherein except containing the carbon polymer of caking not, is feeded other carbon source in described stove.

5. the method for claim 4, wherein to contain other carbon source that carbon polymer feeds in described stove be coal, coke, carbon Jiao (carbon char), charcoal and/or graphite with described.

6. claim 4 or 5 method, wherein said not caking contain carbon polymer and described other carbon source is feeded in described stove with about 1: 1 weight ratio.

7. each method of aforementioned claim, the wherein said not carbon polymer that contains of caking is a plastic waste.

8. each method of aforementioned claim, the wherein said carbon polymer that contains only comprises C, H and optional O atom.

9. each method of aforementioned claim, the wherein said not carbon polymer that contains of caking is feeded in described stove with the form of polymer beads.

10. each method of aforementioned claim, wherein the iron alloy of Sheng Chaning is a steel.

11. not caking contain the iron alloy of carbon polymer in electric arc furnace produce in as the purposes of slag foaming agent.

12. the purposes of claim 13, the production of wherein said iron alloy realizes by each method of claim 1-10.

13. a method of producing iron alloy in electric arc furnace, described method comprises the following steps:

-with the iron alloy raw material described stove of feeding;

-raw material in stove is heated to molten state and forms slag on the melt surface of alloy/raw material; With

-used slag foaming agent effect not caking contain the carbon polymer described stove of feeding.

14. the method for claim 13, the carbon polymer that contains of the described not caking of wherein feeding discharges the reagent that heat energy and generation make slag foaming with burning in described stove and to fused alloy/raw material.

15. the method for claim 14, wherein except making slag foaming,

-cause that the chemical reduction of various metal oxides in the slag is to produce iron alloy; With/

Or

-make slag foaming;

-to the iron that obtains and the alloy carburetting again of carbon.

16. each method of claim 13-15, the additive that wherein said caking contains carbon polymer various metal oxide chemical reductions in causing molten slag is feeded.

17. the method for claim 16, wherein said additive are other carbon sources that claim 4-6 defines in each.

18. each method of claim 13-17, each limits as claim 2-10 in addition for it.

19. a method of operating reheating furnace, it comprises and contains the carbon polymer step of described stove to act as a fuel of feeding with caking not.

20. the method for claim 19, wherein said reheating furnace is operated under the temperature that contains carbon polymer of described not caking that is enough to burn.

21. the method for claim 19 or 20, the temperature of wherein said stove is greater than 1000 ℃.

22. each method of claim 19-21, the wherein said carbon polymer that contains is feeded in described stove with particulate form.

23. each method of claim 19-22, the wherein said not carbon polymer that contains of caking is feeded in described stove with other fuel.

24. the method for claim 23, wherein said other fuel is Sweet natural gas.

25. a system that determines to contain the recirculation of carbon polymer in the stove of the production iron alloy that uses carbon raw material, described system comprises the following steps:

-derive the parameter value of given polymkeric substance, described parameter value reflects the slag foaming ability of described polymkeric substance;

-described parameter and one or more parameter values of being derived by one or more other polymkeric substance are compared;

-from those parameter value ExportRange or scale.

26. the system of claim 25, wherein said parameter are the life-spans of the height and/or the foaming slag of foaming slag.

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