KR101493965B1 - Process for recovering iron and zinc from iron and zinc-bearing waste - Google Patents

Abstract

The present invention provides a method for recovering iron and zinc from iron- and zinc-bearing waste which can greatly improve productivity in the economic aspects by significantly improving the operation stability of a reducing furnace as well as the quality of crude zinc oxide generated when reducing roasting various iron- and zinc-bearing waste including electric arc furnace dust in the reducing furnace. The method for recovering iron and zinc from iron- and zinc-bearing waste comprises the steps of: washing iron- and zinc-bearing dust; manufacturing a briquette; recovering crude zinc oxide; and recovering an iron component.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for recovering iron and zinc from iron-zinc waste materials,

The present invention relates to a process for the recovery of iron and zinc from iron-zinc waste streams comprising iron (Fe) and zinc (Zn).

(Fe, Zn) waste resources such as electric furnace steelmaking dust, casting dust, casting dust, alloy iron dust and sludge of these dusts, high-strength lumps in solidified state or plating sludge in the process of manufacturing various kinds of steel- Are generated in large quantities. Specifically, in Korea, annual electric furnace steelmaking dust is 460,000 tons, casting dust is 50,000 tons, casting dust is 70,000 tons, and zinc plating sludge is 50,000 tons.

Hamcheol Zinc As a waste resource, Hamcheol Zinc dust has low volatile components such as zinc (Zn), lead (Pb), cadmium (Cd), sodium (Na), potassium (K) and chlorine (Cl) Ca), silicon (Si), and other small amounts of heavy metals and dioxins. Since lead (Pb) and cadmium (Cd) in the volatile substance are heavy metals harmful to human body, electric furnace steel dust wastes are designated as specially managed industrial wastes and most of them are landfilled.

However, since Fe, Cr, Ni, or Mn contained in Hamcheol's zinc dust is an industrially useful metal element, it is necessary to use a technically established method to effectively utilize it as a resource and to prevent environmental pollution by harmful substances It is necessary to economically recycle it. Accordingly, much research has been conducted for efficient recycling of the dust, and various new recycling technologies have been proposed.

However, with the recent development of the recycling technology for the electric furnace steelmaking dust, the recycling of electric furnace steelmaking dust has only begun to be made, and iron (Fe), zinc (Zn) and lead (Pb) Development of technology for separation and recovery of valuable metal components and countermeasures against environmental pollution against various harmful components contained therein are insufficient.

Conventionally, as an electric furnace dust treatment technique, specifically, electric furnace dust is mixed as a filling material at the time of ascon production and used for road pavement, or electric furnace steel dust is mixed with coke to form a rotary kiln or a rotary kiln There is a method of reducing and roasting using a reduction furnace called a Rotary Hearth Furnace (RHF).

In both of the above methods, the electric furnace steel dust is reduced and roasted in a reducing atmosphere at a high temperature to collect the zinc component and the low-temperature volatile substances in the dust simultaneously, together with the exhaust gas in the dust collector connected to the reduction furnace, (Hereinafter, referred to as " zinc oxide "), in which zinc is mainly separated and concentrated and recovered. This is an advanced treatment method rather than a conventional method for reclaiming zinc or an ascon filler have.

However, the preliminary reduced iron, which is a by-product obtained by the rotary kiln method, can not be used in the interior of the preliminary reduction iron as shown in the document " INTERNATIONAL SYMPOSIUM ON EAF DUST RECYCLING FOR GREEN GROWTH (THE KOREAN INSTITUTE OF RESOURCES RECYCLING, Since the reduction ratio of the iron (Fe) contained therein is low and a large amount of impurities remain, a method of improving the reduction ratio should be considered in order to use this reduced iron as a raw material for producing pig iron.

Also, in the method using the RHF process, Japanese Patent Laid-Open Nos. 2009-52141 and 2009-079303 disclose a method in which direct briquette is produced with electric furnace dust, and a briquette is directly produced in a rotary furnace Rotary Hearth Furnace (hereinafter referred to as " RHF ") to produce preliminary reduced iron.

However, electric furnace dust includes low-temperature volatile components such as sodium (Na), potassium (K), and chlorine (Cl) components that volatilize within the operating temperature range (about 1000 ° C. to 1350 ° C.) There is a problem that the low temperature volatile components reduce the stability of the operation of the reducing furnace and the quality of the recovered zinc oxide when the single light is directly produced from the electric furnace dust as in the above method and used as the raw material of the RHF.

That is, in the low-temperature volatile component, about one-half of the intestinal material is volatilized in the reducing furnace and discharged together with the exhaust gas, and becomes a fine solid material in the process of lowering the temperature of the exhaust gas component. They are mixed at the same time. Therefore, the zinc content in the dust is lowered, that is, the quality is lowered.

In addition, about 1/2 of the low-temperature volatile component remains in the preliminary reduced iron discharged from the reduction furnace without volatilization, resulting in soft melt fusion, which seriously hinders the operation stability of the preliminary reduction furnace.

Japanese Patent Laid-Open No. 2009-52141 (disclosed on March 12, 2009) Japanese Patent Application Laid-Open No. 2009-079303 (disclosed on April 16, 2009)

 INTERNATIONAL SYMPOSIUM ON EAF DUST RECYCLING FOR GREEN GROWTH, THE KOREAN INSTITUTE OF RESOURCES RECYCLING, 2009, page 91

The present invention relates to a method for producing zinc oxide, which is capable of remarkably improving the stability of the reduction furnace as well as the quality of the zinc oxide generated when the single light of the zinc iron waste is reduced and roasted in the preliminary reducing furnace, And a method for recovering iron and zinc from waste resources.

To achieve the above object, according to an embodiment of the present invention, there is provided a method for manufacturing a zinc dust filter, comprising: washing a zinc dust containing iron and zinc; The washed zinc iron dust dust is mixed with a carbon-based reducing agent selected from the group consisting of coke, anthracite, graphite, coal and a mixture thereof, and a binder selected from the group consisting of water, bentonite and a mixture thereof to obtain an average particle size of 10 mm or less, Producing a single light having a bulk density of 1.5 to 3 g / cm ³ , a water content of 3 to 8 wt%, and a dry compressive strength of 5 to 30 kg / cm 2; Reducing and decomposing the single component in a gas phase at a temperature of 1000 ° C or higher under a supply of combustion air at 150 ° C to 200 ° C using a rotary kiln to recover the zinc component in the vapor phase and recovering it as zinc oxide; And recovering the iron component as molten pig iron and molten slag after the recovering of the zinc oxide, adding the carbon-based reducing agent to the remaining preliminary reduced iron after the removal of the crude zinc oxide, A method of recovering zinc is provided.

In the method for recovering iron and zinc from waste iron zinc waste, a carbon-based reducing agent is further added through a coal-fired system installed in a rotary kiln during the reduction roasting for the single light to reduce the reduction ratio of the pre- And a step of increasing the recovery rate of the adsorbent.

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In addition, the combustion air may be heated by heat exchange with waste heat in the exhaust gas generated during reduction and discharge.

In addition, the preliminary reduced iron may have a softening start temperature of 1200 ° C or higher.

The recovery of the iron component may be carried out by charging the preliminarily reduced iron into which the carbon-based reducing agent has been charged in a heat insulating container, charging the heated precursor directly into the reducing furnace under a heating condition at 800 to 1000 ° C,

In addition, the method for recovering iron and zinc from the iron-zinc waste material may further comprise the step of recycling the molten pig iron to a shot ball for shot blasting and the molten slag to be recycled as a raw material for cement.

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

The method of recovering iron and zinc from the iron-zinc waste material according to the present invention is characterized in that not only the quality of the zinc oxide generated when the iron oxide and the zinc single waste containing iron and zinc are reduced and roasted in the preliminary reducing furnace, The productivity can be greatly improved from the economic point of view.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus for carrying out a method for recovering iron and zinc from a spent iron zinc waste material according to an embodiment of the present invention. FIG.

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.

According to one embodiment of the present invention, productivity of zinc oxide is remarkably improved not only in the quality of zinc oxide generated when the single-shot zinc waste is reduced and roasted in the preliminary reducing furnace but also in the reducing furnace, A method of recovering iron and zinc from iron and zinc containing iron and zinc waste resources is provided.

Specifically, a method of recovering iron and zinc from a spent iron zinc waste material according to an embodiment of the present invention comprises: (1) washing the iron and zinc dust containing iron and zinc; A step (step 2) of producing a briquette by mixing the iron-zinc dust washed with water as a result of the flushing with the carbon-based reducing agent and the binder; The step of reducing and decomposing the zinc component in a gas phase and recovering the zinc component as zinc oxide (Step 3) by reducing and roasting the single-component light at a temperature of 1000 ° C or higher under a supply of combustion air at 150 ° C to 200 ° C using a rotary kiln, ; After the recovery of the zinc oxide, the step of adding the carbon-based reducing agent to the preliminary reduced iron remaining after the separation of the crude zinc oxide and reducing and melting the iron components is recovered as molten pig iron and molten slag (Step 4).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus for carrying out a method for recovering iron and zinc from a spent iron zinc waste material according to an embodiment of the present invention. FIG. FIG. 1 is an illustration only for illustrating the present invention, and the present invention is not limited thereto.

Hereinafter, a method of recovering iron and zinc from iron-zinc waste materials will be described in more detail with reference to FIG.

Step 1 for recovering iron and zinc from the spent iron zinc waste is a step of washing the zinc sulfide dust as a spent iron zinc waste.

The iron-zinc waste material may be iron oxide zinc dust, such as electric furnace steel dust, cast steel and cast iron dust or alloy iron dust, which are generated in the course of manufacturing various steel-related products; A sludge of the dust or a zinc smelting sludge such as a zinc plating sludge; Or a high strength steaming zinc lump in a solidified state. The present invention is characterized in that a cleaning process is carried out on the iron-zinc dust among these iron-zinc waste materials.

Specifically, the iron and zinc-containing dust (or iron-containing zinc dust) 2 generated in the process of manufacturing various steel-related products is stored in the electric furnace dust hopper 1 and then discharged do.

The zinc dust dust 3 discharged from the electric furnace dust hopper 1 is washed with water before charging it into the preliminary reducing furnace.

The washing process for the iron zinc dust 3 can be carried out by washing the iron zinc dust 3 with water. Specifically, the water washing step may be carried out by using a water washing apparatus 4 which mixes and stirs the titanium halide dust and water.

The water (Na), potassium (K), and chlorine (Cl) contained in the iron-containing zinc dust are dissolved and dissolved in the water by the washing process. As a result, the impurity concentration of the zinc oxide obtained by collecting the gas generated in the step of reducing and roasting the single light to the raw material is reduced, and the high purity zinc oxide Can be recovered. In addition, the washing process for the zinc iron dust can increase the softening start temperature of the preliminarily reduced iron to stabilize the operation in the reducing furnace.

Then, one or more of the dewatering and drying processes for removing moisture in the dust may be selectively performed on the zinc dust after the washing process. If the moisture content in the zinc dust is high, the thermal efficiency in the preliminary reduction furnace 32 may be lowered.

The dewatering and drying process may be carried out according to a conventional method. Specifically, the iron oxide zinc dust 3 from which the water-soluble component has been removed is dehydrated and dried through the dehydrator 5, the dehydrated cake 6 and the drier 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 for the iron-zinc dust have a water-soluble heavy metal component in addition to sodium (Na), potassium (K) and chlorine (Cl) (10) and then discharged or reused.

Next, step 2 is a step of mixing monochromic zinc dust 11 washed with water as a result of step 1 above with a carbon-based reducing agent and a binder to produce monochromatic light.

The carbonaceous reducing agent 26 and the binder 27-2 are stored in the respective storage hoppers 25 and discharged and mixed according to the content of the washed iron zinc dust 11 in a suitably controlled amount.

As the carbon-based reducing agent 26, coke, anthracite, graphite, coal and the like may be used. One kind or a mixture of two or more kinds thereof may be used. In consideration of the reduction ratio of zinc and iron to be recovered from the single- It is preferably used in an amount of 5 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of washed zinc iron dust.

The shape or size of the carbonaceous reducing agent 26 is not particularly limited, but an average particle size of 1 mm or less is preferable because the reduction of zinc and iron to be recovered from single light can be optimized.

The binder may be selected from the group consisting of water, bentonite, and mixtures thereof. It is preferable that the binder is used in an amount of 5 to 20 parts by weight, preferably 5 to 16 parts by weight, based on 100 parts by weight of washed zinc iron dust, considering the reduction ratio of zinc and iron to be recovered from single light.

On the other hand, at least one kind of slag component adjusting agent 24 such as limestone, quicklime and the like may be optionally introduced when the washed iron zinc dust 11 is mixed with the carbon-based reducing agent 26 and the binder 27-2.

The slag component adjusting agent preferably has an average particle size of 1 mm or less and is used in an amount of 5 to 20 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the washed iron zinc dust, It is good to be able to optimize the reduction of iron.

Zinc iron sludge, zinc plated steel sheet and the like, which are generated during the process of manufacturing various steel-related products when the washed iron-zinc dust 11 is mixed with the carbon-based reducing agent 26 and the binder 27-2, The step of introducing at least one of the zinc sulfide waste resources out of the sludge or the high-hardness zinc sulfide dust pellets in the solidified state may optionally be further carried out.

In this case, it is preferable that 10 to 100 parts by weight of the spent iron zinc waste material is introduced into 100 parts by weight of washed zinc iron dust.

In addition, when the iron oxide zinc waste is added in the same way as the iron oxide zinc sludge, the drying process is performed as preliminary treatment before mixing with the iron oxide zinc dust, which is washed with water, to prevent reduction in thermal efficiency of the reducing furnace, Lt; / RTI > Further, in the case of the iron oxide zinc dust pellets which are solidified by addition of a binder only for the convenience of transportation in the waste disposal company, the strength is lowered when mixed with the washed iron zinc dust in the state, , It may be preferable to carry out the pulverizing process as a pretreatment before mixing with the washed iron zinc dust.

Specifically, the high-moisture content zinc sulfide sludge 13 having a high water content is subjected to a moisture removal process in the dryer 14 as a pretreatment before mixing with the washed zinc iron dust, and the solid massive zinc oxide dust pellets 16 may be mixed with washed iron oxide zinc dust, a carbonaceous reducing agent and a binder after the pulverization process using the crusher 17 as a pretreatment before mixing.

The dried iron-zinc dust 11, the dried sludge 18, the crushed dust 19, the slag component adjuster 24, the carbonaceous reducing agent 26, and the binder 27-2, which are dried after being washed, (20, 21, 22, 23, 25, 27), and then discharged in a predetermined amount and metered and mixed precisely in the metering device (27).

When the mixture containing the iron-based zinc dust and the powdery carbon-based reducing agent is directly introduced into the closed reduction furnace after the above-described metering and mixing step, the dust particles are scattered to interfere with the reduction of the zinc oxide, Dust particles entering the condenser may lower the recovery rate of metal zinc. Thus, the mixture obtained after the metering and mixing process is formed into a mini-pellet shape by using a mixing pelletizer 29, and a mini-pellet A drying process may optionally be further carried out to ensure that the pellets have an appropriate moisture content and dry compressive strength.

Specifically, the single light produced by the above process preferably has an average particle size of 10 mm or less, and preferably an average particle size of 1 to 10 mm. In addition, the Briquetting is to be preferred having a water content of from 1.5 to 3g / cm ³ and a bulk density of 3 to 8% by weight of. It is also preferable that the single light 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, step 3 is a step of reducing and roasting the single light obtained in step 2 and recovering zinc in the form of zinc oxide.

In the reducing and roasting step, the single light obtained in the step 2 is charged directly into the rotary kiln's preliminary reducing furnace 33, and then heated at a temperature of 1000 ° C. or higher, or 1000 ° C. to 1500 ° C., Lt; 0 > C.

During such a reduction roasting process, low-temperature volatile components such as zinc (Zn), lead (Pb), and chlorine (Cl) are separated from the single light. The exhaust gas of the low-temperature volatile components generated in the preliminary reduction furnace 33 may be purified by a dust collector 39 containing activated carbon after passing through the exhaust gas outlet 38 and may be discharged to the atmosphere from the chimney 42 . At this time, 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 oxidation kiln which forms the high purity zinc oxide with the bag filter, the high purity zinc oxide can be made into the metal zinc by the use of the iron ring source volatilization technique.

On the other hand, among the residues remaining after the separation of the crude zinc oxide, that is, the residues after the zinc component is separated and removed in the vapor phase (hereinafter referred to as the 'preliminary reduced iron'), the gangue component and residual heavy metals By-product, which includes the < RTI ID = 0.0 > EH, the preliminarily reduced iron has an increased softening initiation temperature due to the previous wash process. Specifically, the preliminary reduced iron has a softening initiation temperature of 1200 ° C or higher, or 1230 ° C or higher.

However, since the reduction ratio of the iron oxide in the preliminary reduction furnace is low at about 30%, when it is charged into the melting reduction furnace 45 for the subsequent process in this state, the reaction time and energy required for reduction are consumed excessively, Various operating disturbances may occur in the downstream process. As a result, a carbon-based reductant input port may be provided as a coal combustion system 34-2 on the side of the preliminary reduction iron discharge port of the rotary kiln, which is a preliminary reduction furnace, so that a carbon-based reductant may be additionally supplied depending on the operating conditions. By doing so, the recovery rate of the zinc component can be increased, the reduction ratio of the preliminarily reduced iron such as iron oxide can be improved up to 70%, and the stability of operation in the melting reduction furnace as a subsequent process can be greatly improved.

Accordingly, the method of recovering iron and zinc from the spent iron zinc waste may further include a step of additionally adding the carbon-based reducing agent to the preliminary reduced iron (s) 43 remaining after the zinc oxide is recovered after the recovery of the zinc oxide. The carbon-based reducing agent may be the same as described above, and the additional amount of the carbon-based reducing agent may be appropriately adjusted according to the reduction ratio of the preliminary reduced iron.

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

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 by waste heat recovery and heat exchange is provided in a dust chamber 36 through which exhaust gas (600 ° C. to 900 ° C.) discharged from the rotary kiln 33 passes , A pipe type (C-276) heat exchanger may be installed and LNG combustion air may be passed therethrough to heat the LNG combustion air at 150 to 200 ° C for heat exchange and supply it to the LNG burner 34. By supplying the heated combustion air in this manner, the thermal efficiency and combustion efficiency of the rotary kiln 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 zinc oxide is recovered after the recovery of the zinc oxide and the melt reduction process for recovery of the iron component from the remaining precious reduced iron (43) is carried out. At this time, residual zinc component of 2 to 4% remaining in the preliminary reduced iron can be further recovered in the form of zinc oxide.

Specifically, in the melting and reducing process, the zinc oxide after the recovery of the zinc oxide is separated and the remaining preliminary reducing iron (43) is collected in the heat insulating container, and then charged in the direct reducing electric furnace (45) in a heating state at 800 to 1000 ° C .

In addition, the carbon-based reducing agent and optionally the slag component adjusting agent may be mixed with the preliminary reduced iron (43) and introduced into the melting and reducing furnace (45).

The carbon-based reducing agent and the slag component adjusting agent may be the same as those described above. It is preferable that the carbon-based reducing agent and the slag component adjusting agent each have an average particle size of 1 mm or less, preferably 0.5 to 1 mm each, and it is more preferable that the carbon-based reducing agent and the component adjusting agent have the same particle size have. It is preferable that the carbon-based reducing agent and the slag component adjusting agent are used in an amount of 5 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the preliminary reduced iron, considering reduction optimization of the iron component.

In particular, in the case of cast steel dust having a high purity of cast iron, casting dust, or mill scale, only a carbon-based reducing agent is added to produce monochromatic light, and then added to preheated reduced iron at high temperature discharged from the preliminary reducing furnace, It may be more preferable to heat, reduce and melt.

In addition, the reducing furnace 45 is supplied with combustion air 46 for combustion of the high-temperature exhaust gas in the electric furnace.

The type of the reduction electric furnace 45 is not particularly limited, and may be specifically an induction heating type electric furnace or an arc heating type reduced electric furnace type.

An exhaust gas is generated in the reducing electric furnace 45, and the generated exhaust gas is purified by a dust collector 39 and is also discharged through the stack 42.

On the other hand, in the reducing furnace 45, iron is recovered as the molten slag 52 and the molten pig iron 47 as a result of the melt reduction.

The molten pig iron 47 is sprinkled in a reducing electric furnace 45 and then cooled to a predetermined shape by an ingot casting 48 to be formed into an ingot cast iron or ingot 49. Thereafter, Or as a raw material for the production of steel products of a short ball type or by a water blowing 50 installed on the outside in a reducing electric furnace 45 to be processed into a shot iron ball shaped Pig Iron Ball And can be used for shot blasting or various iron sources.

On the other hand, the molten slag 52 in the reducing electric furnace 45 is discharged from the reduction electric furnace and is slowly cooled in the slag air cooling device 53 to be used as a road wrapping lumber or the like, water blowing (55) to sewn slag (56) and can be used as a raw material for cement.

Accordingly, the method of recovering iron and zinc from the iron-zinc waste material according to the present invention is characterized in that the molten pig iron recovered from the preliminary reduced iron is recovered and converted into a short ball for shot blasting and the molten slag is recovered to be a cement raw material As shown in FIG.

The zinc (Zn) component can be separated and recovered in the form of zinc oxide from the spent steel raw material waste by the above-mentioned method, and the iron (Fe) component is reduced and re- And can be recovered as molten pig iron and molten slag by melting. In addition, this method can remove water-soluble low-temperature volatiles by washing the electric furnace dust beforehand for producing monochromatic zinc chloride, which can economically improve the operation stability of the reducing furnace and the quality of the recovered zinc oxide. In addition, the above method can completely detoxify the preliminary reduced iron, and can greatly improve the productivity in terms of economy. In the method, waste heat in the exhaust gas generated in the reducing furnace is recovered in a dust chamber (a built-in heat exchanger) provided between the dust collector and the reducing furnace, and used for heating the LNG combustion air in the reducing furnace Improves heat efficiency.

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

1, iron oxide and zinc were recovered from the spent iron zinc waste by mixing the iron oxide zinc dust with water in a washing device, and then, with respect to 100 parts by weight of washed iron oxide zinc dust, 50 parts by weight of pulverized coal dust, 50 parts by weight of pulverized coal dust, 15 parts by weight of limestone (average particle size: 1 mm), 10 parts by weight of carbonaceous reductant powder (average particle size: 1 mm) And bentonite were mixed in an amount of 6 parts by weight, respectively, and a mini-pellet-shaped single light was produced through a molding process. The produced single light had an average particle size of 10 mm, a bulk density of 2 to 3 g / cm ³ , a water content in the range of 3 to 6 wt% and a dry compressive strength of 20 kg / cm 2.

The single light thus prepared was charged into a rotary kiln-type preliminary reducing furnace serving as a preliminary reducing furnace, and reduced and roasted at a temperature of 1150 캜 under the supply of combustion air heated to 160 캜. The secondary air for LNG combustion was heated to 160 ° C by heat exchange with the waste heat in the exhaust gas generated in the reducing exhaust gas, and the exhaust gas generated during the reduction roasting was collected through a dust collector to remove zinc components Respectively. The preliminarily reduced iron is mixed with limestone (average particle size: 1.0 mm) and coke powder (average particle size: 1.0 mm) as a carbonaceous reducing agent as a residue remaining after separation of the crude zinc oxide, Directly charged into a reducing electric furnace in a heated state, and subjected to reduction melting under the supply of combustion gas. At this time, limestone and coke were used in an amount of 7 parts by weight based on 100 parts by weight of the preliminary reduced iron. As a result, iron components were recovered as molten pig iron and molten slag.

Comparative Example

In the above example, zinc and iron were recovered in the same manner as described above, except that the cleaning process for the iron-zinc dust was not performed.

Test Example

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

division Suesse
(The presence or absence) Chemical composition (%) Fe Zn Na K Cl C Si Mn P S Electric furnace
Dust radish 27.6 25.5 1.2 3.0 6.6 U 30.5 26.8 0.3 0.7 2.2 Zinc oxide radish 2.1 61.9 2.8 6.2 17.0 U 2.6 73.3 1.4 2.2 8.1 Preliminary reduction iron radish 39.4 2.7 0.3 0.6 0.1 U 39.9 2.6 0.0 0.0 0.0 pig iron radish 92.6 0.0 0.0 0.0 0.0 4.0 0.40 0.30 0.07 0.03 U 93.6 0.0 0.0 0.0 0.0 4.5 0.40 0.32 0.07 0.03 Slag radish 9.6 0.0 0.1 0.3 0.0 U 9.5 0.0 0.1 0.1 0.0

Raw material type Raw material consumption Zinc oxide recovery Pig iron recovery Slag recovery Wash (no water) Washing Wash (no water) Washing Wash (no water) Washing Electric furnace dust 55 (Kg) 20.5 21.5 23.7 23.7 12.7 12.6 Sludge 10 (Kg) Mill scale 10 (Kg) Limestone 11 (Kg) cokes 14 (Kg) Sum 100 (Kg)

As shown in Tables 1 and 2, there was almost no difference in the effect of washing on the environmental aspects between the zinc dust and the zinc dust, but the quality of the zinc oxide was further increased by washing with water.

In addition, changes in the softening initiation temperature of the preliminarily reduced iron by washing with water of zinc iron dust were investigated. The results are shown in Table 3 below.

division Softening start temperature Remarks Wash (no water) 1150 DEG C * Softening start temperature rise by washing Washing 1230 DEG 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 as a result, 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: electric furnace dust hopper 2, 3: iron zinc dust
4: flushing device 5: dehydrator
6: dehydrated cake 7, 14: dryer
8: Washing water waste solution 9: Dehydrated filtrate
10: wastewater treatment apparatus 11: zinc iron dust (washing and drying)
12: High-salt zinc sludge hopper 13: High-water zinc sludge
15: Ham Cheol Zinc Dust Pellet Hopper 16: Ham Iron Zinc Dust Pellet
17: Grinder 18: Dry sludge
19: crushed dust 20: crushed dust hopper
21: Drying sludge hopper 22: Washing and drying dry zinc dust hopper
23: component adjusting agent hopper 24: component adjusting agent
25: Carbon-based reducing agent hopper 26: Carbon-based reducing agent
27: Binder hopper 27-2: Binder
28: Metering and mixing device 29: Single light manufacturing facility
30: Single light 31: Single light dryer
32: single light transport facility 33: preliminary reducing furnace
34: LNG burner 34-2: coal-fired plant
35: Preliminary reduced iron conveying facility 36: Dust chamber (heat exchanger)
37: Hot air transfer pipe 38: Flue gas duct
39: dust collector 40: zinc oxide
41: zinc oxide hopper 42: stack
43: preliminary reducing iron 44: preliminary reducing iron hopper
45: Melting reduction furnace 46: Combustion air
47: molten pig iron 48:
49: ingot 50: rapid quenching plant
51: Particle type pig iron 52: Melted slag
53: slag air cooling device 54: slowly cooled slag
55: Water-proofing equipment 56: Water-cooled slag

Claims (13)

delete delete delete delete delete delete delete Washing the iron-zinc dust containing iron and zinc;
The washed zinc iron dust dust is mixed with a carbon-based reducing agent selected from the group consisting of coke, anthracite, graphite, coal and a mixture thereof, and a binder selected from the group consisting of water, bentonite and a mixture thereof to obtain an average particle size of 10 mm or less, Producing a single light having a bulk density of 1.5 to 3 g / cm ³ , a water content of 3 to 8 wt%, and a dry compressive strength of 5 to 30 kg / cm 2;
Reducing and decomposing the single component in a gas phase at a temperature of 1000 ° C or higher under a supply of combustion air at 150 ° C to 200 ° C using a rotary kiln to recover the zinc component in the vapor phase and recovering it as zinc oxide; And
And recovering the iron component as molten pig iron and molten slag after reducing the zinc oxide and adding the carbon-based reducing agent to the remaining preliminary reduced iron after the zinc oxide is separated and recovering the iron component by reduction and melting. And recovering zinc. 9. The method of claim 8,
Further comprising a step of charging the carbon-based reducing agent through a jacketing system installed in a rotary kiln during the reduction roasting for the single light. 9. The method of claim 8,
Wherein the combustion air is heated by heat exchange with waste heat in an exhaust gas generated at the time of reduction discharge. 9. The method of claim 8,
Wherein the preliminary reduced iron has a softening initiation temperature of 1200 ° C or higher. 9. The method of claim 8,
Wherein the recovery of the iron component is carried out by charging the preliminarily reduced iron into which the carbon-based reducing agent has been charged in a heat insulating vessel and then charging it into a direct reduction electric furnace under a heating condition of 800 ° C to 1000 ° C to reduce and melt the iron. And recovering zinc. 9. The method of claim 8,
Further comprising the step of recycling the molten pig iron to a short ball for shot blasting, and the molten slag to be polished to be a cement raw material, and recovering iron and zinc from the spent iron zinc waste material.

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