KR20200033464A - Manufacturing Methods of Sintered Ferrite Briquette for Iron Manufacture And Manufacturing Apparatus Therefor - Google Patents

Abstract

The present invention relates to a manufacturing method for ferrite briquette using ferruginous sludge generated in an iron-foundry plant. The manufacturing method for ferrite briquette is to manufacture ferrite briquette by supplying a ferruginous sludge raw material into a cement kiln. The cement kiln includes: a preheater including multiple cyclones; and a rotary kiln connected to a lower end of the preheater. The rotary kiln includes a first raw material input port at a rotary kiln inlet. The ferruginous sludge raw material comprises the ferruginous sludge, limestone, and silica, mixed to each other so that the content of ferric oxide (Fe_2O_3) becomes 65-85 wt%. The manufacturing method for ferrite briquette includes: a step of inserting a first ferruginous sludge raw material in which the ferruginous sludge raw material and a reducing agent are mixed into the first raw material input port; and a step of manufacturing ferrite briquette by sintering the ferruginous sludge raw material in a reduction atmosphere formed by the combustion of the reducing agent in the rotary kiln. According to the present invention, the ferruginous sludge having a high content of zinc oxide can be manufactured into the ferrite briquette having a low content of zinc oxide.

Description

Manufacturing method of ferrite briquette for iron products and apparatus used therefor {Manufacturing Methods of Sintered Ferrite Briquette for Iron Manufacture And Manufacturing Apparatus Therefor}

The present invention relates to a method for manufacturing a ferrite briquette for a fired product, and more particularly, to a method for producing a ferrite briquette from iron sludge generated in a steel mill or the like.

Iron sludge includes various types of iron sludge such as steelmaking sludge, Finex sludge, sintered dust, mill scale, iron ore dust and dyed sludge. Iron sludge is oxidized from less than 2% to 30% by weight depending on the plant or process. The zinc content is varied. However, in order to use iron ore as an alternative resource in a steel mill, the content of zinc oxide must be very small. Among the iron sludges generated in the blast furnace and electric furnace processes of the iron and steel industry, sludge with a high content of zinc oxide is buried, which requires a high cost of landfill, and most of the sludge with a low zinc oxide content utilizes itself and some Some of them are used as iron raw materials, one of the subsidiary materials of the cement process. Until now, such iron sludge has been actively researched for recycling worldwide.

Korean Patent Publication No. 1996-0000054 discloses a technique of recycling the slurry into a calcium ferrite after washing the dust and limestone generated in the sintering furnace with a method of manufacturing calcium ferrite, and then recycling the slurry into a sintering furnace.

In addition, Korean Patent Publication No. 2000-0039462 discloses a method of manufacturing a calcium ferrite sintered body using steel-making sludge and limestone sludge having a ferrite content of iron-containing sludge greater than that of the sinter dust collector and having less adverse effects due to alkali and the like. .

This conventional calcium ferrite production technique will be described with reference to FIG. 1. As shown in FIG. 1, after mixing the iron sludge of the iron sludge storage 1 with limestone and the like in the mixer 2, the mixed raw materials are stored in the raw material storage 3 and the quantitative feeder 4 and the bogie 5 are mixed. After being fired in the tunnel furnace 6 through the separator (7), it is manufactured through crushing and particle size screening.

Since this calcium ferrite production technology is a process of mixing to form a granular material and sintering at an appropriate temperature, a mass cannot be used, and since the raw material used contains a large amount of particles larger than 0.1 mm, it is simply mixed with the like to obtain granularity. When firing the assembled, the production of calcium ferrite minerals is reduced due to the difference in local composition, or iron oxide (III) that is not bound to calcium is precipitated as hematite, which can adversely affect the operation.

In addition, these conventional techniques are limited in the treatment of iron-containing sludge with a high zinc oxide content, because they have produced a calcined ferrite product with only iron-containing sludge with little zinc oxide. It has a problem that requires a large amount of energy for removal.

(1) KR B 1996-0000054 (2) KR A 2000-0039462

In order to solve the problems of the prior art, it is an object of the present invention to provide a method of manufacturing ferrite briquettes from high-zinc oxide-containing iron sludge. More specifically, the present invention removes zinc oxide of iron oxide sludge having a high zinc oxide content, replaces and recycles part of the iron ore supplied to the sintering furnace or blast furnace, and at the same time, continuously operates the calcined product of ferrite briquettes to reduce waste emissions. It is an object to provide a manufacturing method.

In addition, in addition to or separately from the above-mentioned object, an object of the present invention is to provide a continuous operation manufacturing method for producing a powder of dry ferrite sludge with a low zinc oxide content as a calcined product of ferrite ore.

In addition, the present invention is a facility and operation for continuously recovering zinc oxide generated by volatilization upon reduction firing at a high temperature to produce high-strength zinc oxide in order to prepare ferrite briquettes of dry crushed powder containing iron oxide sludge with high zinc oxide content in a rotary furnace. It aims to provide a method.

In addition, the present invention has an object to provide an economical and continuous mass production method using a rotary kiln of a cement kiln to partially replace the bulk iron ore supplied to a sintering furnace or blast furnace of a steel mill.

In particular, the present invention also provides a continuous process method for separating zinc oxide in a fine particle state at a high temperature which is volatilized by a reduction reaction and re-oxidized in a rotary kiln of a cement kiln with high purity.

In order to achieve the above technical problem, the present invention is a method of manufacturing ferrite briquettes by injecting raw iron sludge into a cement rotary furnace, wherein the cement rotary furnace includes a preheater having a plurality of cyclones and a rotary furnace coupled to the bottom of the preheater. The rotary furnace is provided with a first raw material inlet of the inlet of the rotary furnace, and the iron sludge raw material is mixed with iron sludge, limestone and silica so that the content of ferric oxide (Fe ₂ O ₃ ) is 65 to 85% by weight. The blended, the first step of injecting the first raw iron sludge raw material containing a mixture of the iron-containing sludge raw material and a reducing agent to the first raw material inlet; It provides a method for producing a ferrite briquette comprising the step of producing a ferrite briquette by firing the raw material for iron-containing sludge in a reducing atmosphere formed by combustion of a reducing agent in the rotary furnace.

The present invention provides a method for producing ferrite ore, characterized in that the content of zinc oxide in the first iron-containing sludge raw material is 2 to 20% by weight of zinc oxide.

In addition, the present invention further comprises the step of injecting the second iron-containing sludge raw material into the second raw material inlet, which is the uppermost inlet of the preheater, wherein the iron-containing sludge in the second iron-containing sludge raw material may have a zinc oxide content of less than 2%.

In order to achieve the above technical problem, the present invention is a method of manufacturing ferrite briquettes by injecting raw iron sludge into a cement rotary furnace, wherein the cement rotary furnace is a preheater having a plurality of cyclones and a rotary furnace coupled to the bottom of the preheater. Including, the rotary furnace is provided with a first raw material inlet of the inlet of the rotary furnace, the preheater includes a second raw material inlet, and the iron-containing sludge raw material is mixed with iron-containing sludge, limestone and silica sand to ferric oxide ( Fe ₂ O ₃ ) is formulated to have a content of 65 to 85% by weight, and the second raw material inlet is fed with an iron sludge raw material having a high zinc oxide content, and at the same time, a reducing agent is added to the first raw material inlet at the entrance of the rotary furnace. To do; And calcining the iron-containing sludge raw material in a reducing atmosphere formed by combustion of a reducing agent in a rotary furnace to produce a ferrite briquette. ;

In the present invention, it is preferable that the basicity ((CaO + MgO) / SiO2) of the ferrite ore fired product is in the range of 0.7 to 3.0 by weight ratio.

In addition, the present invention may further include the step of recovering high purity zinc oxide by drawing a portion of the exhaust gas from the rotary furnace.

The present invention makes it possible to manufacture an iron-containing sludge having a high zinc oxide content in a landfill with ferrite briquettes having a low zinc oxide content. Accordingly, zinc oxide is recovered to recycle unused waste resources, and iron sludge with a low zinc oxide content can also be manufactured from granular ferrite ore and utilized in steel mills.

In addition, it is possible to manufacture ferrite briquettes in granular form by using high-content zinc-containing iron sludge and low-content iron-containing sludge simultaneously.

In addition, in the present invention, it is possible to recover high-purity zinc oxide, and the recovered zinc oxide makes it possible to apply a simple and low-cost reprocessing process in industries that require it.

1 is a diagram schematically showing a conventional calcium ferrite production process.
2 is a view schematically showing the process of drying and grinding the iron sludge, regardless of the size of the zinc oxide content for producing a ferrite ore fired product in the present invention.
3 is a view schematically showing a firing facility for producing a ferrite briquette fired product using a method for drawing out the exhaust gas from a rotary furnace and an iron sludge with a large amount of zinc oxide according to the size of the content of zinc oxide in the iron sludge in the present invention.
4 is a diagram schematically showing an example of a method for recovering zinc oxide in an iron-containing sludge having a high zinc oxide content.
5 is a diagram schematically showing a method for recovering zinc oxide in iron-containing sludge according to a preferred embodiment of the present invention.

Hereinafter, the present invention will be described by describing preferred embodiments of the present invention with reference to the drawings.

2 is a view schematically showing the configuration of a raw material manufacturing equipment for iron-containing sludge raw materials according to an embodiment of the present invention.

In the present invention, the iron sludge raw material manufacturing equipment may provide a raw material in which limestone and silica sand are mixed in the iron sludge, or in addition to the iron sludge raw material including a reducing agent. To this end, as shown in FIG. 2, the raw material manufacturing facility includes an iron sludge reservoir 8, a limestone reservoir 9, a sand reservoir 9-1, and a reducing agent reservoir 11, from each of these reservoirs Sludge, limestone, silica sand and reducing agents are supplied. The supply of each material may be made by a quantitative feeder (8a to 11a, 12) and a bucket elevator (13) that supplies the metered raw materials to the crushing device (14), and is mixed and crushed by the drying and crushing device (14). You can. Of course, this embodiment shows that the iron sludge, limestone, silica sand, and a reducing agent are mixed and supplied in a quantitative manner, but at least some of these materials can be independently quantitatively supplied in a non-mixed state.

The crushing device 14 may be provided with a hot gas inlet 20 for drying the raw material. The dried and crushed raw materials are transported and stored in the raw material storages 17a and 17b through the dust collector 15 to the bucket elevator 16. For example, the iron-containing sludge powder having a high zinc oxide content may be stored in the storage 17a, and the iron-containing sludge powder having little zinc oxide content may be stored and stored in the storage 17b. The dust collector 15 is provided with a suction fan 18 and a chimney 18 to discharge gas.

As described above, when lime iron or sand or a reducing agent is mixed with iron sludge to produce iron sludge raw materials, limestone storage (9) or sand storage (9-1), high-grade reducing agent storage (10), and low-grade reducing agent storage (11) In the limestone, sand or reducing agent is quantitatively blended, and due to the characteristics of the iron sludge, the raw material of the iron sludge is manufactured through drying and grinding because it is in a lump state containing about 50% moisture.

3 is a view schematically showing a ferrite briquetting apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the blended iron sludge powder of the powder reservoirs 17a and 17b of FIG. 2 is introduced into a firing device such as a cement rotary furnace. As shown, the firing device comprises a preheater 22, a calcination furnace 23, a rotary furnace 24 and a cooler 25.

The preheater may include multi-stage cyclones such as 4- to 5-stage cyclones 22a, 22b, 22c, 22d, and 22e. In this embodiment, it is illustrated that the preheater is composed of a 5-stage cyclone. The preheater and the calcination furnace increase the temperature of the raw material before firing in the rotary furnace 24 to save energy. The raw material that has passed through the uppermost cyclone and calcination furnace of the preheater is preheated to a temperature of approximately 900 ° C or less, such as 600 to 900 ° C.

In the firing apparatus of the present invention, the raw material has two inflow paths.

First, the raw material is introduced into the rotary furnace along a flow path leading to the rotary furnace via the pre-heater top cyclone, the 4-stage cyclone, the 3-stage cyclone, the 2-stage cyclone, the calciner and the lowermost cyclone. To this end, the preheater is provided with an upper raw material inlet. Preferably, the raw material is an iron sludge raw material in which iron sludge, limestone and silica sand are mixed.

Next, the raw material may be injected through the lower raw material inlet of the rotary furnace inlet. At this time, the raw material is an iron-containing sludge raw material containing a reducing agent. In addition, according to another embodiment of the present invention, the lower raw material input port may be introduced solely with a reducing agent. In the present invention, various reducing agents may be used, and for example, reducing agents based on carbon may be used.

In the present invention, the rotary furnace is maintained at a temperature of about 1000 to 1350 ° C, and the raw material for iron-containing sludge is fired. The reducing agent introduced into the rotary furnace is burned and locally maintains the inside of the rotary furnace in a reducing atmosphere, and the raw material for iron-containing sludge is fired in a reducing atmosphere. In the present invention, the calcination reaction of the iron-containing sludge can be expressed by the following series of chemical formulas.

(Formula 1)

Combustion reaction

(1) C + 0.5O ₂ → CO

(2) C + O ₂ → CO ₂

(3) C + CO ₂ → 2CO

(Formula 2)

 Reduction reaction

(1) Fe ₃ O ₄ + CO → 3FeO + CO ₂ ,

(2) FeO + CO → Fe + CO ₂ ,

(3) 3ZnO · Fe ₂ O ₃ + 3C → 3ZnO + 2Fe ₃ O ₄ + 3CO

(4) ZnO + CO → Zn + CO ₂

(5) PdO + CO → Pd + CO ₂

(Formula 3)

Oxidation reaction

(1) Zn + 0.5O ₂ = ZnO,

(2) Pb + 0.5O ₂ = PbO

As shown in the above reaction formula, zinc oxide contained in the raw material of the iron-containing sludge is reduced by reacting with a carbon source (CO) as shown in the formula (4) at a high temperature of the rotary furnace.

Therefore, it is possible to remove excess zinc oxide in the raw material of iron-containing sludge by using a reducing agent. On the other hand, the reduced zinc is oxidized again by contacting air in the rest of the rotary furnace.

In the calcined product of the ferrite briquette manufactured in the present invention, carbon remains due to incomplete combustion, and the residual carbon can be mixed like coke in a sintering furnace or blast furnace, and reacts at a high temperature of 1300 ° C in a rotary furnace to ferrite briquette. The component has an iron component, which can improve the productivity of the steelmaking process.

In the present invention, the iron-containing sludge powder containing zinc oxide is reduced in a rotary furnace through a combustion reaction such as Chemical Formulas 1 to 2, a reduction reaction, and a reoxidation reaction through the reaction of Chemical Formula 3.

On the other hand, in the case of zinc oxide generated by volatilization during the reduction firing of ferrite briquettes, the exhaust gas of the rotary furnace contains volatilized zinc oxide and iron dust, so if the total amount of exhaust gas is collected, the purity of zinc oxide is very low. In the present invention, in order to increase the purity of zinc oxide, a portion of high-temperature exhaust gas from a rotary furnace containing iron dust and volatilized zinc oxide is drawn out to cool the high-temperature exhaust gas and separate the cooled exhaust gas and zinc oxide to obtain high purity. Zinc oxide can be produced.

The ferrite briquettes manufactured through the rotary furnace 24 are collected through the cooler 26, and the briquettes with a small particle size of less than 1 mm are discharged from the cooler 26 to be collected by the dust collector 27 to produce a ferrite briquette fired product. do. Meanwhile, the coal grinder 50 of FIG. 3 supplies fuel to the burner 51 of the rotary furnace.

The above-described ferrite briquette manufacturing apparatus of the present invention can manufacture ferrite briquettes using an iron-containing sludge raw material having various concentrations of zinc oxide. Specifically, the present invention can produce a ferrite briquette having a low concentration of zinc oxide content from an iron-containing sludge raw material having a high concentration of zinc oxide content. Therefore, in the present invention, a raw material for iron-containing sludge having various zinc oxide contents can be used. For example, a high-concentration iron-containing sludge raw material having a zinc oxide content of 2 to 20% by weight in the iron-based sludge can be used, and the zinc oxide content is 2 A low-concentration iron-containing sludge raw material of less than weight percent may be used.

Hereinafter, the operation method of the firing apparatus of the present invention will be described.

A. High concentration ZnO iron sludge

The raw material for iron-containing sludge having a high concentration of zinc oxide content is introduced into the raw material lower inlet 30 of the inlet of the rotary furnace of FIG. 3. At this time, a reducing agent may be mixed with the aforementioned raw material for iron-containing sludge or a reducing agent may be added separately from the raw material for iron-containing sludge.

Zinc oxide in the raw material of iron-containing sludge volatilizes at 1000 to 1350 ° C, which is the firing temperature range of the rotary furnace, and zinc oxide is reduced by the reaction of Formulas 1 and 2 by combustion of the reducing agent. Of course, at this time, the reduction of the iron oxide component according to Chemical Formulas 1 and 2 also proceeds, and the final product, ferrite ore, has a high iron component.

The raw iron sludge raw material is supplied to the rotary furnace 24 using fossil fuel through the lower raw material inlet 30 and fired, so that the particle size of 1 ~ 50mm becomes a calcined product of about 1000 ~ 1350 ℃ and cooled in the cooler 25. As it is cooled with air in the air flowing into the fan 26, it becomes a fired product of the final product, ferrite briquettes. At this time, the exhaust gas of the burnt rotary furnace is discharged through the lower gas pipe 32 of FIG. 3 without going through the cyclone preheaters 22a to 22e. At this time, the lower damper 34 is opened and the upper damper 33 is operated in a closed state.

B. High concentration ZnO iron sludge

On the other hand, when the iron sludge and the reducing agent are added to the upper raw material inlet of the preheater of the firing device, the temperature of the preheater is lower than 900 ° C, so the vapor pressure of zinc oxide is very low, so the introduced reducing agent does not function as a reducing agent and burns. . Therefore, the introduced reducing agent cannot substantially contribute to the reduction of zinc oxide.

In this embodiment, a high concentration zinc oxide-containing iron sludge is introduced into the raw material inlet of the top of the preheater while the reducing agent is introduced into the raw material inlet 30 of the inlet of the rotary furnace.

The raw material of the iron sludge that has passed through the preheater and the calcination furnace is supplied to the rotary furnace 24 and reduced and calcined together with the reducing agent introduced into the lower material inlet 30 to become a calcined product having a particle size of 1 to 50 mm in the range of 1000 to 1350 ° C. As it is cooled with air in the air flowing into the cooling fan 26 from the cooler 25, it becomes a fired product of the final product, ferrite briquettes.

In this embodiment, the exhaust gas from the rotary furnace burned through the rotary furnace is discharged to the forced suction fan 31 while passing through the cyclone preheaters 22a to 22e. In this case, the upper damper 33 must be opened and the lower damper 34 must be closed.

C. Low concentration ZnO-containing iron sludge top input

As the raw material of iron-containing sludge containing zinc oxide having a low concentration (less than 2% by weight) is supplied to the upper raw material inlet 29 of the preheater of the firing apparatus of FIG. 3 described above, 4 to 5 stage cyclone preheaters 22a to 22d are provided. Preheated while passing sequentially, the iron sludge powder collected in the lowermost cyclone preheater 22e further heated in the calcination furnace 23 is supplied to the rotary furnace 24 using fossil fuel. In this example, the use of a reducing agent is unnecessary. As the raw material input to the rotary furnace is fired, the particle size of 1 ~ 50mm is about 1000 ~ 1350 ℃ and cooled by air in the air flowing from the cooler 25 to the cooling fan 26. It becomes the character. The exhaust gas burned in the rotary furnace is discharged by the forced suction fan 32 while passing through the cyclone preheaters 22a to 22e. In this case, the upper damper 32 must be opened, and the lower damper 34 must be closed to operate.

Hereinafter, a method of recycling zinc oxide in the firing apparatus of the present invention will be described.

4 is a view for explaining an example of a zinc oxide collecting device.

Referring to Figure 4, the zinc oxide content is 15 to 20% of the iron-containing sludge powder or a raw material containing a reducing agent and a reducing agent is introduced into the rotary furnace 38 through a quantitative feeder 35 and a supply pipe 36 And fired in a reducing atmosphere. The fired product is discharged through the rotary furnace hood 39. On the other hand, all of the exhaust gas including the high temperature exhaust gas of about 700 to 800 ° C in the rotary furnace 38, iron dust and volatilized zinc oxide is drawn out and collected in the settler 37, and then collected through the cooler 40. In (41), zinc oxide containing iron powder and gas are separated to recover zinc oxide. Since the zinc oxide is mixed with the recovered iron oxide, the concentration of zinc oxide is lowered to about 50 to 70%, and in the related process for utilizing it, there is a problem of reprocessing again to increase purity.

5 is a view for explaining a continuous method for recovering high purity zinc oxide according to a preferred embodiment of the present invention.

A portion of the high-temperature exhaust gas of about 700 to 800 ° C discharged from the rotary furnace 24, including zinc oxide, is drawn out to the drawing pipe 43. In the present invention, it is preferable that the ratio of the outgoing gas in the total exhaust gas is 10 to 50 vol% by volume ratio. Within this withdrawal range, the cast iron dust in the rotary furnace is submerged by its own weight, so the withdrawal gas may contain only a small amount of cast iron dust.

The cooling fan 44 cools the exhaust gas at a high-temperature rotation to 200 ° C. or less to separate the exhaust gas and zinc oxide from the dust collector 45, and the separated zinc oxide is stored in the zinc oxide reservoir 47. In this process, 80-90% or more of high-purity zinc oxide can be produced, the subsequent process to utilize it is simplified, and it takes less energy and is economical. The reaction formulas for reduction and oxidation of the iron oxide sludge powder with a high content of zinc oxide are as shown in Chemical Formulas 1 to 3 described above.

Hereinafter, preferred embodiments of the present invention will be described.

<Example 1: High concentration ZnO-containing iron sludge firing>

The chemical composition of the iron sludge, limestone, and sand of this example is shown in Table 1, and the analysis values of the high-grade and low-grade reducing agents are shown in Table 2.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO TiO ₂ and others Ig.loss Iron Sludge 1 1.5 1.4 75.8 6.6 1.1 1.5 9.1 0.6 2.4 Ham Sludge 2 4.6 2.5 75.2 8.7 0.1 2.5 4.3 0.4 1.7 Limestone 1.9 0.6 0.5 52.8 0.1 0.7 - 44.0 sand 96.5 1.95 0.1 0.2 - 0.2 - 1.0

division Fixed carbon Volatile Ash Sulfur powder Advanced reducing agent 85.6 1.3 11.7 0.6 Low-grade reducing agent 57.6 5.1 36.5 0.8

Table 3 is a table showing the results of analyzing the chemical composition of the ash contained in the coal fuel input to the ash of the reducing agent in Table 2 and the rotary furnace.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO Ig.loss Reducing agent ash 66.8 24.9 4.9 1.1 1.2 0.8 - Fuel (coal) ash 63.8 27.1 4.5 3.4 0.2 1.0 -

To produce calcined products of ferrite briquettes, iron sludge 1 in Table 1, iron sludge 2, and limestone were blended, and the amount of the reducing agent to react with zinc oxide contained therein was calculated and blended. same.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO TiO ₂ and others Ig.loss reducing agent Ingredients 2.8 1.8 69.9 7.1 0.6 1.9 6.2 0.5 1.9 7.4

Since the blended raw materials in Table 4 have a high content of zinc oxide, the furnace is heated by staying in the firing furnace for 60 minutes at the same temperature in the reducing atmosphere to 1300 ° C by applying the rotary furnace firing method in which the blended raw materials are added to the lower raw material supply pipe 30. The degree of reaction of the characteristics was compared.

The blending raw material was introduced into the lower raw material supply pipe 30 using a firing device as shown in FIG. 3. In the rotary furnace, it is estimated that the temperature of the blended raw material at this time is about 600 ~ 800 ℃ when the blended raw material is introduced into the supply pipe, and this is calcined to 1300 ℃ for 60 minutes and discharged from the rotary furnace. The number of revolutions was adjusted. Then, the upper damper 33 of FIG. 3 was closed, and the lower damper 34 of FIG. 3 was opened and operated. At this time, the exhaust gas from the rotary furnace was lowered in the cooler and then collected by the dust collector and then discharged to the outside.

The firing test was conducted in an electric furnace for comparison with the present invention. When firing the blended raw material in an electric furnace, the starting temperature was set to 600 ° C and heated to 1300 ° C. On the other hand, in the electric furnace, the heat source is electricity, and the inside of the electric furnace has less vapor pressure of zinc oxide than the rotary furnace, so that zinc oxide is less volatilized.

Table 5 below is a table showing the results of component analysis of the fired products obtained in Comparative Examples and Examples. Ferrite briquettes fired in the reducing condition of the rotary furnace of the present invention have very low zinc oxide content as shown in Table 5, and can be used as a part of iron ore replacement in a steel mill.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO TIO ₂ and others
heavy metal basicity Example 1 (rotational furnace) 5.4 2.9 80.2 8.2 0.7 2.1 0.45 0.5 1.91 Comparative example (electric furnace) 4.4 3.0 81.5 7.1 0.5 1.4 1.60 0.5 1.93

The burned product of the waste light ore fired in the rotary furnace of the present invention has a high volatilization rate of zinc oxide of 92.8%, so it is possible to recycle iron sludge in a steel mill, and even if it contains ash of coal used as fuel, the Fe ₂ O ₃ content It can be seen that there are no problems with recycling of other ingredients.

Table 6 shows the results of analyzing the mineral of the ferrite ore produced by the firing method by X-ray diffraction analysis. The effect of the reducing agent not only volatilizes zinc oxide contained in the iron sludge, but also reduces some of the iron oxide to convert it into iron.

division Iron Alpha
(α-Fe) Wuestite
(FeO) Merwinite
Ca ₃ Mg [SiO ₄ ] ₂ ) Gehlenite
(Ca ₂ Al [Al SiO ₇ ]) Magnetite
(Fe ^{+ 2} Fe ^{+ 3} ₂ O ₄ ) Hematite
(Fe ₂ O ₃ ) Example 1 26.6 18.7 16.6 20.4 11.8 5.0

On the other hand, the electric furnace method of the comparative example has a problem that mass production is impossible and energy consumption is too large. In addition, above all, it can be seen that the content of zinc oxide exceeds 1% compared to the present invention, and thus, restrictions on recycling of iron-containing sludge follow.

<Example 2: Low concentration ZnO-containing iron sludge firing>

The chemical composition of iron sludge, limestone and sand with a low zinc oxide content is as shown in Table 7 as a blending raw material for making the ferrite fired product of the present invention.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO TiO ₂ Ig.loss Iron Sludge 3 6.6 4.7 68.6 3.8 0.6 0.8 0.46 0.5 12.34 Iron Sludge 4 1.5 0.4 84.0 8.7 0.2 1.5 2.32 0.5 0 Limestone 1.9 0.6 0.5 52.8 0.1 0.7 - 44.0 sand 96.5 1.95 0.1 0.2 - 0.2 - 1.0

Table 7 shows the blended raw materials mixed with iron sludges 3 and 4 and limestone or sand in Table 7.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO TiO ₂ and others Ig.loss Ingredients 4.2 2.7 75.9 7.3 0.5 1.2 1.60 0.5 6.1

Since the blending raw material of Table 8 has a small amount of zinc oxide, a rotary furnace firing method in which the blending raw material is added to the upper raw material supply pipe 29 in FIG. 3 was applied.

As in Comparative Example 1, compared with the electric furnace firing method, the reaction degree of the calcined products heated by staying in the firing furnace for 60 minutes up to 1300 ° C was compared. When firing the blended raw material in an electric furnace, the starting temperature was set to 600 ° C and heated to 1300 ° C. In the case of the embodiment, the gas temperature when the blended raw material was supplied from the supply pipe in a rotary furnace in which the blended raw material was introduced into the upper raw material supply pipe 29 The temperature of the compounding material at this time is estimated to start at about 600 ~ 800 ℃, and this is calcined to 1300 ℃ for 60 minutes to adjust the number of revolutions of the rotary furnace to discharge it from the rotary furnace. At this time, the upper damper 33 of FIG. 3 was opened, and the lower damper 34 was closed and operated.

Table 9 shows ferrite briquettes fired in the rotary furnace of the present invention and the electric furnace of the comparative example. This ferrite ore can be used as a part of iron ore in the steel mill.

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO SO ₃ MgO ZnO Heavy metals other than TIO ₂ Example 2 (rotational furnace) 4.7 2.9 82.9 6.8 0.4 1.3 0.8 0.5 Comparative Example 2 (electric furnace) 4.4 2.8 82.7 6.7 0.4 1.3 1.2 0.5

Among the burned components of the waste light ore fired in the rotary furnace of the present invention, the cause of the reduction of zinc oxide even without a reducing agent is among the carbon monoxide and the Ig-loss contained in the blended raw materials while firing the blended raw materials to 1300 ° C. This is because some of the unburned carbon acted as a reducing agent. Therefore, iron-containing sludge with little zinc oxide content can be made of ferrite ore and recycled in steel mills. On the other hand, ferrite ore can be produced in an electric furnace, but as described above, it is impossible to mass-produce realistically, and it is difficult to consume large amounts of energy.

Table 10 shows the results of analyzing the mineral of the ferrite ore produced by the firing method by X-ray diffraction analysis.

division Iron Alpha
(α-Fe) Wuestite
(FeO) Merwinite
Ca ₃ Mg [SiO ₄ ] ₂ ) Gehlenite
(Ca ₂ Al [Al SiO ₇ ]) Magnetite
(Fe ^{+ 2} Fe ^{+ 3} ₂ O ₄ ) Hematite
(Fe ₂ O ₃ ) Example 2 (rotational furnace) 1.1 5.3 5.8 19.0 18.9 49.9

<Example 3: Production of high purity zinc oxide>

As in Example 1, while producing ferrite briquettes in the rotary furnace, the ratio of the drawn-out gas among the 700-800 ° C high-temperature exhaust gases discharged from the rotary furnace was varied to 10-100 vol%. It was withdrawn through the withdrawal tube (43). When air is blown into the drawn-out gas with a cooling fan (42) to cool the exhaust gas at a high temperature of 700 to 800 ° C to 200 ° C or less, and the exhaust gas from the cooled rotary furnace collects zinc oxide in the dust collector (44), The purity of zinc oxide is shown in Table 11.

division 100% withdrawal 50% withdrawal 30% withdrawal Withdrawal amount 10% Example 3 37% 65% 83% 95%

Although the zinc oxide concentration of the iron-containing sludge powder of Table 11 is less than 7%, the purity of zinc oxide can be adjusted according to the amount of the exhaust gas from the rotary furnace. However, in the conventional method as shown in Fig. 4, even if the zinc oxide concentration of the iron-containing sludge powder is 15 to 20% or more, the purity of zinc oxide is as low as 50 to 70%.

1: Iron Sludge Storage 2: Mixer
3: powder raw material storage 4: quantitative feeder
5: Balance 6: Tunnel
7: Shredding and particle size selection 8: Iron sludge storage
8a: iron sludge quantitative supply meter 9: limestone storage
9a: Limestone quantitative supply meter 9-1: Sand storage
9-1a: Sand metering meter 10: Advanced reducing agent
10a: High-grade reduction agent quantitative supply meter 11: Low-grade reduction agent
11a: Low-quantity reducing agent metering meter 12: Integrated transport transport belt
13: Raw material transport bucket elevator 14: Drying and crusher
15: dust collector 16: product transport bucket elevator
17a, 17b: iron sludge powder storage
18: suction fan 19: chimney
20: hot gas inlet 21: iron sludge powder extraction
22: Preheater
22a: Top Cyclone 22b: Fourth Cyclone
22c: 3-stage cyclone 22d: 2-stage cyclone
22e: Cyclone at the bottom 23: Hazor
24: Furnace 25: Cooler
26: cooling fan 27. dust collector 28: chimney
29: raw material upper inlet 30: raw material lower inlet
31: suction fan 32: rotary exhaust gas pipe
33: upper damper 34: lower damper
35: iron raw material quantitative feeder 36: iron raw material supply pipe
37: settler 38: rotary furnace
39: rotary hood 40: cooler
41: dust collector 42: chimney
43: rotary outlet pipe 44: cooling fan
45: dust collector 46: suction fan
47: zinc oxide cellar 48: chimney
50: coal grinder 51: rotary burner

Claims (6)

In the method for producing ferrite briquettes by injecting raw iron sludge into a cement rotary furnace,
The cement rotary furnace includes a preheater having a plurality of cyclones and a rotary furnace coupled to the lower end of the preheater, and the rotary furnace includes a first raw material inlet of a rotary furnace inlet,
The iron-containing sludge raw material is a mixture of iron-containing sludge, limestone and silica sand so that the content of ferric oxide (Fe ₂ O ₃ ) is 65 to 85% by weight,
Inputting a first iron-containing sludge raw material in which the iron-containing sludge raw material and a reducing agent are mixed into the first raw material inlet;
A method for producing a ferrite briquette, comprising firing the raw material for iron-containing sludge in the reducing atmosphere formed by combustion of the reducing agent in the rotary furnace to produce a ferrite briquette. According to claim 1,
The method of manufacturing ferrite briquettes, characterized in that the content of zinc oxide in the first iron-containing sludge raw material is 2 to 20% by weight of zinc oxide. According to claim 2,
The preheater is provided with a second raw material inlet,
Further comprising the step of injecting the second iron sludge raw material into the second raw material inlet of the preheater,
Method for producing ferrite ore, characterized in that the content of zinc oxide in the second iron-containing sludge raw material is less than 2% zinc oxide. In the method for producing ferrite briquettes by injecting raw iron sludge into a cement rotary furnace,
The cement rotary furnace includes a preheater having a plurality of cyclones and a rotary furnace coupled to the bottom of the preheater, wherein the rotary furnace includes a first raw material inlet of a rotary furnace inlet, and a preheater is a second raw material inlet. Including,
The iron-containing sludge raw material is a mixture of iron-containing sludge, limestone and silica sand so that the content of ferric oxide (Fe ₂ O ₃ ) is 65 to 85% by weight,
Inputting a raw material for iron-containing sludge having a high zinc oxide content into the second raw material inlet and simultaneously introducing a reducing agent into the first raw material inlet of a rotary furnace inlet; And
A method for producing a ferrite ore comprising firing the raw material for iron-containing sludge in a reducing atmosphere formed by combustion of a reducing agent in a rotary furnace to produce a ferrite ore. The method according to any one of claims 1 to 4,
Method for producing a ferrite briquette characterized in that the basicity ((CaO + MgO) / SiO2) of the ferrite briquette calcined product ranges from 0.7 to 3.0 by weight. The method according to any one of claims 1 to 4,
And extracting a portion of the exhaust gas from the rotary furnace to recover high purity zinc oxide.

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