KR101493968B1 - Process for recovering valuable metals from wastes produced during the manufacture and the processing of stainless steel - Google Patents

Abstract

The present invention provides a method for recovering valuable metals from waste generated during the manufacture and processing of stainless steel, which can improve the recovery rate and quality of valuable metal elements and a continuous operation rate by improving the operation stability of a subsequent smelting reduction electric arc furnace while improving the quality of crude zinc oxide recovered when reducing roasting various waste generated during the manufacture and processing of stainless steel in a preliminary reducing furnace. The method of the present invention comprises the steps of: washing stainless steel dust; manufacturing a briquette; recovering crude zinc oxide; and recovering valuable metal components.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering valuable metals from stainless steel manufacturing processes and processing wastes. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering valuable metals from wastes generated in a stainless steel manufacturing process and a processing process.

STS steelmaking processes such as mill scale, annealing and pickling line shot blasting, pickling after neutralization sludge, CCIM sludge, etc., together with steel dust in stainless steel electric furnaces, Wastes are generated, and STS processing wastes such as chips or scraps are produced in the processing of stainless steel several hundred thousand tons a year.

In particular, STS steelmaking dust, sludge, mill scale, pickled sludge, etc., which are STS steelmaking process wastes, contain Zn, Pb, Cd, Na, K, Volatile gangue components such as calcium (Ca), aluminum (Al), silicon (Si), magnesium (Mg) and the like are contained mainly in the low temperature and the dioxins containing a small amount of heavy metals and toxic have. Particularly, since lead (Pb) and cadmium (Cd) in volatile substances are heavy metals harmful to human body, they are classified as [special designated wastes] and strictly manage the treatment process by law.

However, since the Fe, Cr, Ni, Mn and Mo components contained in the STS steelmaking process waste are metal elements which are industrially very useful, in order to effectively utilize them as resources and prevent environmental pollution by harmful people, It is necessary to economically recover and recycle these components using a safe method. To this end, advanced industrial countries have been conducting a lot of research for efficient recycling of STS steelmaking process waste and STS processing waste, and new recycling technologies have been continuously proposed.

Specifically, in Japanese Patent Laid-Open Nos. 2009-079303 and 2004-076152, a briquette is produced by mixing STS electric furnace steelmaking dust and a carbon reducing agent, and then a rotary hearth furnace (hereinafter referred to as RHF ), The zinc component contained in the single light is volatilized and transferred to the exhaust gas, the exhaust gas is collected in the dust collector, the zinc component is concentrated and collected in the dust collected, and the metal iron, A method of simply collecting and reusing an effluent containing iron oxide, iron oxide, gangue, and residual heavy metals in a vessel in a cooled state and simply recharging it in the first STS melting furnace is disclosed.

Generally, STS steelmaking process wastes contain a large amount of low-temperature volatile components volatilizing at the operating temperature range (about 1100 to 1250 ° C) of the above-mentioned reducing furnace. Therefore, the STS steelmaking process waste directly produces mono- , The low-temperature volatile components not only make the operation of the preliminary reducing furnace unstable, but also adversely affect the quality of recovered zinc oxide (hereinafter referred to as 'crude zinc oxide'). . In addition, the operation of the smelting and reducing furnace, which is a post-process, has a crucial influence on the operation, and the continuous operation can not be performed.

In other words, about 1/2 of the low-temperature volatile components in the intestinal material are volatilized in the preliminary reducing furnace and are discharged together with the exhaust gas. As the temperature of the exhaust gas component is lowered, fine oxide dusts are mixed into the exhaust gas, The content of the zinc component in the zinc oxide recovered in the dust collecting filter of the dust collector is lowered, that is, the quality of the zinc oxide product is lowered. The remaining one-half of the low-temperature volatile components in the enteric material are not volatilized but remain in the reduced iron and other gangue components (hereinafter referred to as 'STS reserve reduced iron') discharged from the preliminary reducing furnace, And the stability of the operation of the preliminary reduction furnace.

Japanese Patent Application Laid-Open No. 2009-079303 (disclosed on April 16, 2009) Japanese Patent Laid-Open No. 2004-076152 (published on November 11, 2004)

The present invention relates to an STS steelmaking process capable of economically and efficiently recovering STS molten pig iron by enhancing the stability of the STS reduction roaster and the melting reduction furnace and thus greatly improving the quality and recovering rate of zinc oxide, And a method for recovering a valuable metal from the metal.

According to an embodiment of the present invention, there is provided a method of manufacturing a stainless steel-made steel pipe, comprising: washing stainless steel-made steel dust obtained by collecting exhaust gas generated in an electric furnace for stainless steel-making steel; 10 to 20 parts by weight of a carbonaceous reducing agent selected from the group consisting of coke, anthracite and mixtures thereof is mixed with 100 parts by weight of the stainless steel manufacturing process waste to 100 parts by weight of the washed stainless steelmaking dust, And 5 to 10 parts by weight of a binder selected from the group consisting of water, bentonite and mixtures thereof, and then mixing the slag preparation selected from the group consisting of limestone, quicklime and mixtures thereof with a basicity (C / S) Is 1.5 to 2.5, then a single light having an average size of 5 to 20 mm, a bulk density of 1.5 to 3 g / cm 3, a water content of 5 to 8 wt%, and a dry compressive strength of 5 to 30 kg / Producing; Reducing and decomposing the single light in a preliminary reduction furnace of a rotary kiln to separate the zinc component into vapor phase and recovering it as zinc oxide; After recovering the zinc oxide, the zinc oxide is separated from the single light and the remaining stainless steel preliminary reduced iron having a softening start temperature of 1280 ° C or higher is mixed with the single light of the stainless steel processing waste, the carbonaceous reducing agent and the slag preparation And then melt-reduced at a temperature of 1580 DEG C or higher to melt a valuable metal component including iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and molybdenum (Mo) Recovering the recovered metal as slag, and a method of recovering valuable metals from the processing waste.

The STS steelmaking process and the method for recovering the valuable metal from the processing waste may further include a step of further adding a carbonaceous reducing agent so that the reduction ratio of the single light is 70% or more.

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The method for recovering valuable metals from the STS steelmaking process and the processing process waste may include preparing the stainless steel ingot by molding and cooling the molten pig iron, or converting the molten pig iron into a spherical stainless steel shot ball, and The method may further include the step of recycling the molten slag as either a stone, a cement raw material, or a lozenge by cooling or sintering the molten slag.

Other details of the embodiments of the present invention are included in the following detailed description.

The present invention relates to a method for efficiently recovering valuable metals from wastes generated in an STS steelmaking process and a processing step, and not only is it possible to simultaneously improve the stability of the reduction roasting furnace and the quality of zinc oxide, The melting and reducing operation in the electric furnace is made more stable, and the valuable metal can be effectively recovered in the form of STS pig iron.

1 is a schematic view of an apparatus for performing a method for recovering valuable metals from waste generated in a STS steelmaking process and a manufacturing process according to an embodiment of the present invention.

The present invention is capable of various modifications and various embodiments and is intended to illustrate and describe the specific embodiments in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present invention, considering the constitutional characteristics of STS steelmaking process waste and processing process waste at the time of recovery of valuable metals from STS steelmaking process waste and STS process process waste produced in steel making and processing of stainless steel (STS) In detail, STS steelmaking dust containing a large amount of volatile components among STS steelmaking process wastes is washed with water before preliminary reduction to remove alkaline components and Cl components in advance, thereby improving the operational stability of the preliminary reduction process STS steelmaking process waste except for STS steelmaking dust is formed into a single light form together with washed STS steelmaking dust to be preliminary reduced and then reduced by melting, , STS processing process wastes, which have few volatile components and pulsating components, After the molding in the form by charging a smelting reduction furnace by melt reduction treatment with STS preliminary reduced iron, it characterized in that a more efficient recovery of valuable metals from the STS steel making process waste and processing waste.

That is, the STS steelmaking process and the method for recovering valuable metals from the processing wastes according to an embodiment of the present invention include washing the STS steelmaking dust obtained by collecting exhaust gas generated in the electric furnace for stainless steel making (step 1); (Step 2) mixing STS steelmaking dust washed with water as a result of the flushing with STS steelmaking process waste, carbon-based reducing agent, conditioning agent and binder to prepare single-phase light; Reducing the single light in the preliminary reducing furnace to separate the zinc component and recover it as zinc oxide (step 3); The STS preliminary reduced iron having a softening start temperature of 1280 DEG C or higher, which is obtained by separating the zinc oxide from the single-phase light, is mixed with the STS processing process waste single light, the carbon-based reducing agent and the preparation and then melted and reduced at a temperature of 1580 DEG C or higher, (Step 4) of recovering valuable metal components including Fe, Ni, Cr, Mn, and Mo as STS molten pig iron and molten slag.

1 is a schematic view of an apparatus for performing a method for recovering valuable metals from waste generated in a STS steelmaking process and a manufacturing process according to an embodiment of the present invention. FIG. 1 is an illustration only for illustrating the present invention, and the present invention is not limited thereto.

This will be described in more detail with reference to FIG.

Step 1 for recovery of valuable metals from waste generated in the STS steelmaking process and processing step is to wash the STS steelmaking dust obtained by collecting the exhaust gas generated in the STS steelmaking furnace.

The STS steelmaking dust is STS electric furnace dust (2) obtained in the process of refining the exhaust gas generated in the electric furnace during the STS steelmaking process, and contains a large amount of volatile components among the STS steelmaking process waste.

The STS electric furnace dust 2 is stored in the STS electric furnace dust hopper 1 and then discharged from the hopper 1 at a predetermined amount according to the start of the collection process. The STS electric furnace dust 3 discharged from the STS electric furnace dust hopper 1 is treated with water before being charged into a reduction electric furnace for reducing roasting. The washing process for the STS electric furnace dust 3 can be performed by washing the STS electric furnace dust 3 with water. Specifically, the above-mentioned water washing step can be carried out by using the water washing apparatus 4 which mixes and stirs the STS electric furnace dust 3 and water.

The water-soluble components such as sodium (Na), potassium (K), and chlorine (Cl) contained in the STS electric arc furnace dust 3 are dissolved in water and removed by the water washing process. As a result, the concentration of impurities in the single step (or pellet) produced in the subsequent step is lowered. As a result, the concentration of impurities in the resultant dust obtained by collecting and purifying the exhaust gas generated in the step of reducing and roasting the single- High zinc oxide can be recovered. In addition, the washing step for the STS electric furnace dust 3 can prevent coagulation of the preliminary STS reduced iron discharged from the preliminary reducing furnace by increasing the softening start temperature of the preliminarily reduced iron, and can greatly stabilize the operation.

If the water content in the STS electric furnace dust (3) subjected to the water washing process is high, the thermal efficiency of the preliminary reducing furnace may be lowered. Therefore, in the dehydration and drying process for removing moisture in the dust for the cleaned STS electric furnace dust One or more processes may optionally be further performed.

The dewatering and drying process may be carried out according to a conventional method. Specifically, the washing STS electric furnace dust from which the water-soluble component has been removed is dehydrated and dried through the dehydrator 5, the dehydrating cake 6 and the dryer 7, and then stored in the storage hopper 22.

On the other hand, since the water washing waste liquid 8 and the dehydrated filtrate 9 after washing the STS electric furnace dust contain a small amount of a water-soluble heavy metal component in addition to sodium (Na), potassium (K) and chlorine (Cl) And can be reused after being finally processed in the apparatus 10. [

Step 2 is a step of mixing STS steelmaking dust, STS electric furnace dust 11, which has been washed and dried in step 1, with various STS steelmaking process wastes, a carbonaceous reductant, a preparation material, and a binder to produce single light.

Specifically, the STS steelmaking process waste may include mill scale, cutting chips, neutralized sludge after pickling, or blast (blast) generated in the STS steelmaking process in addition to steelmaking dust generated in the stainless steel electric furnace steelmaking process. ), It is preferable that the sludge or waste containing the valuable metal components such as Fe, Cr, Ni, Mn and the like is introduced and mixed in an amount of 10 to 50 parts by weight based on 100 parts by weight of the washed STS steelmaking dust .

The mixing process of the STS steelmaking process waste and the washed STS steelmaking dust may be carried out according to a conventional method.

However, if the STS steelmaking process wastes mixed with the STS steelmaking dust have a large amount of water, the drying process is carried out as preliminary treatment before mixing with the washed STS steelmaking dust, thereby reducing the thermal efficiency of the reducing furnace, Lt; / RTI > If the STS steelmaking process wastes have a large amount of particles such as wheat scale or a large amount of solidly solidified lumps, when mixed with the STS steelmaking dust washed in this state, Therefore, it may be preferable to carry out the grinding process as a pretreatment before mixing with the washed STS steelmaking dust.

Specifically, the high-water-content STS steelmaking process waste 13 having a high water content is subjected to a process of removing moisture from the dryer 14 as a pretreatment before mixing with washed STS steelmaking dust, In the case of a solid massive STS steelmaking process and processing process waste 16, after the grinding process using the grinder 17 is performed as pre-mixing pretreatment, the water-washed dry STS electric furnace dust ( 11, the carbon-based reducing agent 26, and the slag preparation 24.

On the other hand, when the STS steelmaking process waste and the washed STS steelmaking dust are mixed, the carbon-based reducing agent 26 and the slag forming agent 24 are mixed with each other to promote reduction of the mixture of the STS steelmaking process waste and the washed STS steelmaking dust .

Examples of the carbonaceous reducing agent include coke, anthracite, graphite, and coal, and one kind or a mixture of two or more of them may be used.

The carbonaceous reducing agent 26 is stored in the carbon-based reducing agent hopper 25 and discharged and mixed according to the contents of the cleaned STS electric furnace dust and the STS steelmaking process waste. The carbon-based reducing agent 26 may be added in an amount of 10 to 20 parts by weight, or 10 to 20 parts by weight based on 100 parts by weight of the total amount of the STS electric furnace dust and STS steelmaking process waste washed in consideration of the reduction rate of the valuable metal oxide to be recovered from the single- 15 parts by weight may be preferably used.

Although the shape or size of the carbonaceous reducing agent 26 is not particularly limited, it is preferable that the carbonaceous reducing agent 26 has an average particle size of 0.5 mm or less because the reduction of the valuable metallic element to be recovered from the single light can be optimized.

As the slag conditioning material 24, limestone or quick lime can be cited. One of them or a mixture of two or more of them can be used.

The slag preparation material preferably has the same particle size as that of the carbon-based reducing agent when homogeneous mixing is taken into consideration. Specifically, it may be preferable that the slag preparation material has an average particle size of 0.5 mm or less.

The slag conditioning material 24 is stored in the slag conditioning hopper 23 and discharged and mixed according to the content of the washed STS electric furnace dust and STS steelmaking process waste. Specifically, it is preferable that the slag conditioning material 24 is used in an amount such that the basicity (C / S) of the washed STS electric furnace dust and the STS steelmaking process waste mixture is 1.5 to 2.5, It is preferable to use 5 to 10 parts by weight based on 100 parts by weight of the total sum of STS electric furnace dust and STS steelmaking process waste.

The STS steelmaking dust 11, the dry STS steelmaking process waste sludge 18, the pulverized STS steelmaking process waste dust 19, the slag conditioning material 24 and the carbonaceous reducing agent 26, which are washed and dried, , 21, 22, 23, 25, and then discharged in a predetermined amount and mixed uniformly in the mixing device 28. [

Further, when the mixture containing STS steelmaking dust, STS steelmaking process waste, powdery carbonaceous reducing agent, and slag formulating agent is directly introduced into the closed reduction furnace after the mixing process as described above, dust particles are scattered, And the scattered dust particles may simultaneously degrade the quality of the zinc oxide in the dust chamber. Accordingly, the mixture is processed into a single-color form using a short-holder 29, and a drying process is selectively performed using a dryer 31 so that the single-color light has an adequate moisture content and a dry compressive strength .

In the molding step in the monochromator, a binder 27-2 for promoting the bonding of the mixture may be added.

The binder 27-2 may be water, bentonite, or a mixture thereof. In consideration of the reduction ratio of the valuable metal to be recovered from the single light, the binder 27-2 may be added to the total amount of 100 parts by weight of the washed STS electric furnace dust and STS steelmaking process waste 5 to 10 parts by weight may be preferably added.

The single light 31 produced by the above process has an average particle size in the range of 5 to 20 mm, preferably 10 to 15 mm, a bulk density of 1.5 to 3 g / cm ³ and a moisture content in the range of 5 to 8 wt% May be preferred. It is also preferable that the single light 31 has a dry compressive strength in the range of 5 to 30 kg / cm 2. When the average particle size, the bulk density, the moisture content and the dry compressive strength are as described above, the handling property in the subsequent process is excellent, and the sufficient strength and porosity required in the reducing and roasting process, Excellent volume stability.

Next, in step 3, the single light obtained in step 2 is reduced and roasted in the preliminary reducing furnace to recover the zinc component as zinc oxide.

The reducing roasting may be carried out by charging the single light obtained in the step 2 into a rotary kiln as the preliminary reducing furnace 33 and then heating it to a temperature of 1050 ° C or more, or 1050 to 1250 ° C.

During such a reducing and roasting process, low-temperature volatile components such as zinc (Zn), lead (Pb), chlorine (Cl), and the like are separated into gas phase in single light.

The high-temperature flue gas containing the low-temperature volatile component generated in the preliminary reduction furnace 33 heats the air in the heat exchanger 36-2 provided in the dust chamber 36, (37) to the combustion air of the LNG burner for heating the preliminary reduction furnace. The exhaust gas passing through the heat exchanger is collected in the dust collector 39 through the exhaust gas discharge passage 38 and then purified and discharged to the atmosphere through the stack 42. At this time, the dust collector 39 may contain a purifying agent, specifically, an active carbon for purification of exhaust gas.

The dust 40 collected by the dust collector 39 is zinc oxide containing a high concentration zinc component. The recovered zinc oxide can be stored in the storage hopper 41 and then recovered as metal zinc through a conventional zinc smelting process. Specifically, after collecting the chloride collected in the preliminary reduction furnace for producing high purity zinc oxide by a bag filter, zinc oxide may be dissolved in sulfuric acid and electrolytic smelting may be performed to produce metal zinc, So that the high purity zinc oxide can be made of metal zinc.

On the other hand, the residue (hereinafter referred to as 'STS preliminary reduced iron') 43 after the separation of the crude zinc oxide contains byproducts such as metallic iron, iron oxide, and gangue ingredient. The STS preliminary reduction iron (43) has an increased softening start temperature due to the water washing process, specifically, a softening start temperature of 1280 ° C or higher.

However, since the reduction ratio of the STS preliminary reducing iron 43 in the preliminary reducing furnace 33 is low at about 30%, when the reducing furnace 47 for the subsequent process is charged in this state, the reaction time and energy Is excessively consumed, and various operating disturbances may occur in the downstream process. As a result, a carbon-based reductant inlet port may be provided as a coal combustion system 34-2 on the side of the reduced iron discharge port of the preliminary reducing furnace 33, and carbon-based reductant may be additionally supplied depending on the operating conditions. That is, the method for recovering valuable metals from the stainless steel manufacturing process and the processing process wastes according to the present invention may further include a step of charging the carbonaceous reducing agent through the jacketing system installed in the preliminary reducing furnace at the time of reducing roasting for the single light . By doing so, the recovery rate of zinc can be increased, the reduction ratio of preliminarily reduced iron can be improved to 70%, and the stability of operation in the subsequent reduction furnace can be greatly improved. The carbon-based reducing agent may be the same as described above.

An LNG burner 34 using liquefied natural gas (LNG) as fuel may be used for the purpose of supplying the heat source of the preliminary reducing furnace 33.

However, when low-temperature atmospheric air is used as the LNG combustion air, the thermal efficiency and the LNG combustion efficiency may be lowered. Therefore, it is desirable to increase the thermal efficiency and the LNG combustion efficiency by using the heated air. To this end, a secondary combustion air preheating system for waste heat recovery and heat exchange in a dust chamber 36 through which exhaust gas (600 ° C. to 900 ° C.) discharged from the preliminary reducing furnace 33 passes, C-276), it is preferable to heat the LNG combustion air at a temperature of 150 to 200 占 폚 by passing the LNG combustion air through the heat exchanger, and supply the LNG burning air to the LNG burner. By supplying the heated combustion air in this manner, the thermal efficiency and combustion efficiency of the preliminary reducing furnace 33 can be greatly improved. In addition to the secondary combustion air preheating system by the waste heat recovery and heat exchange, the oxygen enrichment supply system can be selectively installed to further increase the efficiency.

Subsequently, in STEP 4, the STS preliminary reduced iron (43) is separated from the crude zinc oxide and mixed with the STS processing process waste single light, the carbon-based reducing agent and the preparation, and then a melt reduction process is carried out to recover the valuable metal components.

In the melting and reducing process, a mixture of the STS precious reduction iron (43) and the STS processing waste is charged in the melting reduction electric furnace (47), and the combustion air preheated to the inside is supplied from the top of the melting reduction electric furnace Can be carried out by heating.

The STS processing waste is a waste such as a chip or a scrap which is generated in the processing steps of stainless steel and is processed into a single light shape 46 and stored in the STS processing waste storage hopper 45 , And STS preliminary reduction iron (43) to the electric furnace (47) to perform the melting reduction. The STS treated waste 46 may be used in an amount of 10 to 50 parts by weight based on 100 parts by weight of the STS precious reduced iron (43).

The carbon-based reducing agent 26 and optionally the slag conditioning material 24 may be charged into the reduction furnace 47 together with the STS precious reduction iron 43 and the STS processing waste 46. The carbon-based reducing agent 26 and the slag preparation 24 may be the same as those described above. The carbon-based reducing agent 26 and the slag conditioning agent 24 may each preferably have an average particle size of 0.5 mm. In terms of mixing homogeneity, the carbon-based reducing agent and the slag preparation agent preferably have the same particle size have. The carbon-based reducing agent and the slag preparation 24 may be used in an amount of 5 to 10 parts by weight based on 100 parts by weight of the total amount of the STS reduced iron and the STS processing waste, considering the reduction rates of valuable metals such as Fe, Cr, and Ni Lt; / RTI >

The melting and reducing furnace 47 may be an arc heating type reduced furnace type favorable for reducing properties and may be a combustion furnace for reoxidizing the volatile metallic elements in the high temperature exhaust gas generated in the melting and reducing furnace 47 May be supplied through the preheating air supply device (48). The combustion air may be preheated air or the like.

The exhaust gas after the re-oxidation treatment is purified by the dust collector 39-2 and is discharged through the chimney 42 as well.

On the other hand, useful metal elements such as Fe, Ni, Cr, Mn, or Mo components are separated as the STS molten pig iron 49 and the molten slag 54 as a result of the melting and reducing reaction in the melting reduction furnace 47 Is recovered.

The recovered STS molten pig iron 49 is spouted in the melting and reducing electric furnace 47 and then shaped and cooled into a predetermined shape in the coagulator 50 to be an STS ingot 51. Thereafter, Or a ball type STS pig iron 53 which is a spherical stainless steel ball by a water blowing 52 attached to the melting and reducing electric furnace 47 It can be used as a raw material for stainless steel making or as a shot blast ball.

The melted slag 54 in the melting and reducing furnace 47 is spouted in the melting and reducing electric furnace, is naturally cooled in the slag air-cooling device 55 and then used as the stone as the slowly cooled slag 56, It can be used as a raw material for cement or as a raw material as water-chain slag 58 due to high-pressure water sprayed from a slag water blower 57 such as a high-pressure water spray device installed outside the reduction electric furnace 47 .

Accordingly, the method for recovering valuable metals from the stainless steel manufacturing process and the process wastes according to the present invention is characterized in that the molten pig iron recovered from the preliminary reduced iron is recovered and shrunk to a shot ball for shot blasting and the molten slag is recovered as a raw material for cement The method comprising the steps of:

The zinc (Zn) component can be separated and recovered in the form of zinc oxide from the STS steelmaking process waste and processed waste generated in the electric furnace for stainless steel manufacturing by the above-mentioned method, and the remaining Fe, Cr, Ni, Mn, Mo Can be recovered as STS pig iron and molten slag by melt reduction. In addition, in the above method, the water-soluble low-temperature volatile components are removed by washing with water before STS steelmaking dust is produced, thereby improving the operational stability of the reduction furnace and the quality of the recovered zinc oxide economically. In addition, this method improves the stability of the operation of the preliminary reduction furnace by raising the softening start temperature of the preliminarily reduced iron, and completely renders the preliminary reduced iron completely harmless and economical.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

Example

The apparatus shown in FIG. 1 was used to recover valuable metals from STS steelmaking process waste and processing process waste.

Specifically, STS electric furnace dust obtained by collecting exhaust gas generated in an electric furnace for STS steelmaking was mixed with water in a washing device, washed, and then dried. 50 parts by weight of dry dust having dried sludge of high-water STS steelmaking process waste, 50 parts by weight of crushed dust pulverized by massive STS steelmaking process waste, 100 parts by weight of limestone (average particle size: 0.5 (C / S value = 2) of a mixture of STS electric furnace dust and STS steelmaking process wastewater, which was washed with water, and 20 parts by weight of a coke powder (average particle size: 0.5 mm or less) as a carbon- , 6 parts by weight of water and bentonite as a binder were further mixed together, and monolayer was produced through a molding process in the form of pellets. The single light produced herein had an average particle size of 10 to 20 mm, a bulk density of 2 to 3 g / cm ³ , a moisture content in the range of 5 to 8 wt% and a dry compressive strength of 20 kg / cm 2.

The single light thus prepared was charged into a preliminary reducing furnace for reducing roasting, and then reduced and roasted in a temperature range of 1050 DEG C or higher. The exhaust gas generated at this time was collected through a dust collector to recover the zinc component in the form of zinc oxide. Further, 50 parts by weight of STS processing wastes including machined chips and cutting scraps generated during the STS processing step were mixed with STS preliminary reduced iron (softening start temperature: 1280 DEG C or higher), which is the remaining residue of the crude zinc oxide, (Average particle size: 0.5 mm or less) and coke (average particle size: 0.5 mm or less) were added and mixed. At this time, limestone and coke were used in an amount of 10 parts by weight based on 100 parts by weight of the total amount of STS precious reduced iron and STS processing waste. The resultant mixture was charged into a melting reduction electric furnace and subjected to reduction melting at a temperature of 1580 DEG C or more while supplying combustion air preheated to 150 to 200 DEG C from the top of the melting reduction electric furnace. As a result, STS melting reduction pig iron and molten slag containing valuable metals such as Fe, Cr, Ni and the like were recovered.

Comparative Example

In the above example, the STS steelmaking process waste and the valuable metals in the processing waste were recovered in the same manner as above except that the STS electric furnace dust was not washed.

Test Example

As in the above examples and comparative examples, the change in grade and the change in the recovered yield of STS electric furnace dust were evaluated according to the presence or absence of washing. The results are shown in the following Tables 1 and 2, respectively.

division Suesse
The presence or absence Chemical composition (%) Fe Cr Ni Zn Na K Cl C Si Mn P S STS Steelmaking
waste Wash (no water) 30.0 10.0 2.0 10.0 3.0 2.0 1.0 - - - - - Washing 32 10.6 2.1 10.1 0.6 0.4 0.3 - - - - - Coarse oxidation
zinc Wash (no water) 5.1 1.1 0.2 47.9 14.1 9.9 5.2 - - - - - Washing 6.6 1.4 0.3 59.1 5.2 4.1 2.0 - - - - - Preliminary STS
Reduced iron Wash (no water) 38.5 8.0 1.6 0.8 0.5 0.4 0.0 - - - - - Washing 39.0 8.1 1.6 0.8 0.2 0.1 0.0 - - - - - STS pig iron Wash (no water) 77.2 12.7 2.9 0.0 0.0 0.0 0.0 4.4 0.4 2.0 0.07 0.03 Washing 78 15.0 3.5 0.0 0.0 0.0 0.0 4.4 0.4 2.0 0.07 0.03 Slag Wash (no water) 7.1 4.2 0.3 0.0 0.2 0.1 0.0 - - - - - Washing 7.2 4.2 0.1 0.0 0.1 0.0 0.0 - - - - -

Raw material type  usage Zinc oxide recovery STS iron recovery Slag recovery Wash (no water) Washing Wash (no water) Washing Wash (no water) Washing STS steelmaking dust 55 (Kg) 9.5 10.1 28.7 32.7 18.4 17.1 Sludge 10 (Kg) Mill scale 10 (Kg) Limestone 11 (Kg) cokes 14 (Kg) Sum 100 (Kg)

As shown in Tables 1 and 2, the effect of the STS electric furnace dusting on the environment was not significantly different, but the degree of zinc oxide was further increased when the water was washed.

In addition, changes in the softening start temperature of the preliminarily reduced iron by washing with STS electric furnace dust were examined. The results are shown in Table 3 below.

division Softening start temperature Remarks Wash (no water) 1175 ℃ * Softening start temperature rise by washing Washing 1290 ° C

As shown in Table 3, when the softening temperature of the preliminarily reduced iron was varied depending on whether or not the washing was carried out, it was confirmed that the softening start temperature was increased when washing with water, and the operation of the reducing furnace was remarkably stabilized.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

1: STS electric furnace dust hopper 2, 3: STS electric furnace dust
4: flushing device 5: dehydrator
6: dehydrated cake 7: dryer
8: Washing water waste solution 9: Dehydrated filtrate
10: Wastewater treatment device 11: STS electric furnace dust (washed and dried)
12: STS steelmaking process waste water hopper
13: STS steelmaking process waste in high water
14: dryer 15: massive STS steelmaking process waste hopper
16: Massive STS steelmaking process waste
17: Grinder 18: Dry STS steelmaking process Waste sludge
19: Grinding STS Steelmaking process Waste dust
20: pulverized dust hopper 21: dried sludge hopper
22: Washing and drying STS electric furnace dust hopper
23: slag setting hopper 24: slag setting material
25: Carbon-based reducing agent hopper 26: Carbon-based reducing agent
27: Binder hopper 27-2: Binder
28: Mixer (metering function) 29: Short burner
30: Single light 31: Single light dryer
32: Single light transport facility 33:
34: LNG burner 34-2: Projection system
35: Preliminary reduction iron transportation facility 36: Dust chamber
37: heated air transfer line (heat exchange) 38, 38-2: exhaust gas transfer line
39, 39-2: dust collector 40, 40-2: zinc oxide
41: zinc oxide hopper 42: chimney (Stack)
43: STS preliminary reduced iron 44: Preliminary reduced iron feed insulation hopper
45: STS processing process waste hopper 46: STS processing process waste
47: Melt reduction electric furnace 48: Preheating air supply device
49: STS molten pig iron 50: STS pig iron setter
51: STS Ingot 52:
53: STS spherical iron 54: molten slag
55: slag air cooling device 56: slowly cooled slag
57: slag shredding device 58: sewed slag

Claims (12)

delete delete delete delete delete delete delete delete Washing the stainless steel-made steel dust obtained by collecting exhaust gas generated in an electric furnace for stainless steel-making steel;
10 to 20 parts by weight of a carbonaceous reducing agent selected from the group consisting of coke, anthracite and mixtures thereof is mixed with 100 parts by weight of the stainless steel manufacturing process waste to 100 parts by weight of the washed stainless steelmaking dust, And 5 to 10 parts by weight of a binder selected from the group consisting of water, bentonite and mixtures thereof, and then mixing the slag preparation selected from the group consisting of limestone, quicklime and mixtures thereof with a basicity (C / S) Is 1.5 to 2.5, then a single light having an average size of 5 to 20 mm, a bulk density of 1.5 to 3 g / cm 3, a water content of 5 to 8 wt%, and a dry compressive strength of 5 to 30 kg / Producing;
Reducing and decomposing the single light in a preliminary reduction furnace of a rotary kiln to separate the zinc component into vapor phase and recovering it as zinc oxide; And
After recovering the crude zinc oxide, the stainless steel preliminary reduced iron having the softening start temperature of 1280 ° C or higher remaining after the separation of the crude zinc oxide in the single light was mixed with the single light of the stainless steel processing waste, the carbonaceous reducing agent and the slag preparation Molybdenum reduction at a temperature of 1580 占 폚 or higher so that a valuable metal component including iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and molybdenum (Mo) And recovering the valuable metal from the stainless steel manufacturing process and processing wastes. delete 10. The method of claim 9,
Further comprising a step of adding a carbon-based reducing agent so that the reduction ratio of the single light is 70% or more. 10. The method of claim 9,
The molten pig iron is molded and cooled to produce a stainless steel ingot, or the molten pig iron is subjected to a water-sintering process to convert it into a spherical stainless steel shot ball, and
Further comprising the step of recycling the molten slag as one of a stone, a cement raw material and a lozenge by cooling or sintering the molten slag, and recovering the valuable metal from the stainless steel manufacturing process and the processing process waste.

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