A method for removing dioxins using electrolytic manganese slag

Abstract

The present invention relates to a method for removing dioxins by using electrolytic manganese slag, belonging to the technical field of metallurgical environmental protection. The method includes mixing iron ore, fuel, flux and iron-containing dust slag to obtain a first mixture; wherein the iron-containing dust slag contains low-chlorine electric field dust, and the chlorine element content in the low-chlorine electric field dust is 2% - 10%; mixing the electrolytic manganese slag with high-chlorine electric field dust to obtain a second mixture; wherein the chlorine element content in the high-chlorine electric field dust is greater than 10%; after mixing the first mixture and the second mixture, sintering is carried out, and the sintering flue gas generates electric field dust and waste gas after passing through an electrostatic precipitator; detecting the toxicity equivalent concentration of dioxins in the waste gas, and discharging when the toxicity equivalent concentration of dioxins ≤ 0.5 ng-TEQ / m<supgt;3< / supgt;. The present invention realizes the efficient treatment of dioxins and the comprehensive utilization of electrolytic manganese slag and electric field dust.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical environmental protection, and in particular to a method for removing dioxins by utilizing electrolytic manganese slag. Background Art

[0002] With the gradual implementation and completion of the ultra-low emission transformation project in the steel industry, the iron ore sintering process has achieved SO 2 、NO x The comprehensive treatment of dust and dioxin is the most toxic substance known in the world and is difficult to be eliminated by natural degradation. The treatment of dioxin in iron ore sintering is still in its infancy and has not yet reached a level below 0.5ng-TEQ / m 3 emission standards.

[0003] According to the urgent need for reducing dioxin emissions in the iron ore sintering production process, a method for removing dioxins in the iron ore sintering production is urgently needed to effectively reduce the emission of dioxins in the iron ore sintering production and achieve the goal of green production of iron ore sintering. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a method for removing dioxins using electrolytic manganese slag, so as to remove dioxins in iron ore sintering production, so that the emission concentration of dioxins reaches the national standard and the purpose of green production of iron ore sintering is achieved.

[0005] In one aspect, the present invention provides a method for removing dioxins using electrolytic manganese slag, comprising the following steps:

[0006] S1: mixing iron ore, fuel, flux and iron-containing dust to prepare a first mixed material;

[0007] The iron-containing dust slag contains low-chlorine electric field dust removal ash, and the chlorine content of the low-chlorine electric field dust removal ash is 2%-10%;

[0008] S2: mixing electrolytic manganese slag with high-chlorine electric field dust removal ash to obtain a second mixed material;

[0009] The chlorine content in the high-chlorine electric field dust removal ash is greater than 10%;

[0010] S3: mixing the first mixed material and the second mixed material, and then sintering the mixed material to generate dust and waste gas;

[0011] S4: Detect the toxic equivalent concentration of dioxins in the waste gas. When the toxic equivalent concentration of dioxins is ≤0.5ng-TEQ / m 3 Discharge at the time.

[0012] When the first mixed material and the second mixed material are sintered, dioxins are generated. The present invention utilizes electrolytic manganese slag to catalytically degrade dioxins at 150-250° C. to generate carbon dioxide, hydrogen chloride and water. The reaction equation is shown in (1).

[0013]

[0014] Electrolytic manganese slag is waste generated in the process of producing pure manganese through electrolysis and reduction methods. It is mainly transported to storage yards and stored in wet dams. This not only occupies a large amount of land, but also allows a large amount of harmful substances to penetrate into the soil, surface water and groundwater, posing serious environmental pollution and safety hazards.

[0015] The research found that there is MnO in electrolytic manganese slag. x It can catalyze dioxins under low temperature environment, achieve the purpose of dioxin removal and efficient degradation, and at the same time realize the recycling of electrolytic manganese slag, reducing the harm of electrolytic manganese slag to the land.

[0016] In addition, electric field dust removal ash is generated during the steel production process, and the electric field dust removal ash contains a large amount of iron and carbon elements. In order to save costs, most steel companies return the electric field dust removal ash to the iron ore sintering process for recycling. However, the electric field dust removal ash also contains chlorine, and chlorine is one of the important elements for the formation of dioxins. Therefore, the present invention adds low-chlorine electric field dust removal ash with a chlorine content of 2%-10% to iron-containing dust slag for recycling, and adds high-chlorine electric field dust removal ash with a chlorine content greater than 10% to electrolytic manganese slag. While catalytically degrading dioxins through the electrolytic manganese slag, the contact between chlorine and hydrocarbons is reduced, thereby achieving efficient control of dioxins, so that the toxic equivalent concentration of dioxins is ≤0.5ng-TEQ / m 3 , and the comprehensive utilization of electrolytic manganese slag and electric field dust removal ash.

[0017] Furthermore, in step S1, in terms of mass percentage, the iron ore is 70% to 85%, the fuel is 6% to 9%, the flux is 9% to 15%, and the iron-containing dust is 5% to 15%.

[0018] Furthermore, the proportion of particles with a diameter of less than 38 μm in the low-chlorine electric field dust removal ash is less than 65%.

[0019] Furthermore, in step S2, the mass ratio of the electrolytic manganese slag to the high-chlorine electric field dust removal ash is 10-30.

[0020] Furthermore, the proportion of particles with a diameter of less than 30 μm in the electrolytic manganese slag is greater than 85%, and the MnO in the electrolytic manganese slag is x The content is 8% to 10%.

[0021] Furthermore, the proportion of dust particles with a diameter of less than 38 μm in the high-chlorine electric field dust removal is greater than 90%.

[0022] Furthermore, in step S3, the mass ratio of the second mixture to the first mixture is 0.05 to 0.2.

[0023] Furthermore, in step S3, when the chlorine content in the dust removal ash is ≤10%, it is returned to the iron-containing dust slag; when the chlorine content in the dust removal ash is greater than 10%, it is returned to the electrolytic manganese slag.

[0024] Furthermore, the toxic equivalent concentration of dioxins in the waste gas is less than 0.1 ng-TEQ / m 3 ; Dust concentration <20mg / m 3 .

[0025] Furthermore, the method for removing dioxins by electrolytic manganese slag comprises the following steps:

[0026] Step 1, adding iron ore, fuel, flux and iron-containing dust into a first drum mixer according to a certain ratio to prepare a first mixture, and adding water to mix;

[0027] Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation;

[0028] Step 3, mixing the electrolytic manganese slag and the high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation;

[0029] Step 4, mixing the granulated first mixed material and the second mixed material in a corresponding proportion, and then evenly spreading them on a sintering trolley for sintering to generate sintering fume;

[0030] Step 5: The sintering flue gas enters the dust collector for dust removal under the action of the dust removal fan, generating dust removal ash and waste gas;

[0031] Step 6: After desulfurization and denitrification treatment, the exhaust gas can be discharged through a chimney to meet the emission standards.

[0032] On the other hand, the present invention provides a device for removing dioxins generated during iron ore sintering, comprising an electrolytic manganese slag bin, a high-chlorine electric field dust removal ash bin, a disc pelletizing machine, an iron ore bin, a fuel bin, a flux bin, an iron-containing dust slag bin, a first drum mixer, a second drum mixer, a sintering trolley, a flue, a sintering fan, an electric precipitator, a dust removal fan, a desulfurization device, a desulfurization induced draft fan, a denitrification device, a denitrification induced draft fan and a chimney.

[0033] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0034] 1. The present invention makes full use of the catalytic degradation function of electrolytic manganese slag on dioxins and the formation mechanism of dioxins in the iron ore sintering process, thereby achieving efficient control of dioxins in the iron ore sintering process and resource utilization of electrolytic manganese slag.

[0035] 2. The present invention mixes electrolytic manganese slag with high-chlorine electric field dust removal ash to form granules, which can effectively inhibit the formation of dioxins during the iron ore sintering process on the one hand, and on the other hand, improve the permeability of the sintering material layer, promote the catalytic degradation function of electrolytic manganese slag on dioxins and improve the quality of sintered ore, thereby achieving a dioxin removal rate of more than 90% during the iron ore sintering process.

[0036] 3. The present invention can realize the efficient and reasonable utilization of sintering electric field dust removal ash. On the one hand, a small amount of undegraded dioxins in the sintering flue gas can be combined with a certain amount of MnO x The dust removal ash is further catalytically degraded; on the other hand, the high-chlorine electric field dust removal ash is mixed with electrolytic manganese slag to be granulated to effectively inhibit dioxins in the sintering process, and the low-chlorine electric field dust removal ash is used as a raw material for iron ore sintering production for secondary resource utilization, saving the dioxin control costs and production costs of the iron ore sintering process.

[0037] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0039] Figure 1 This is a schematic diagram of the process of removing dioxins using electrolytic manganese slag;

[0040] In the figure, 1. electrolytic manganese slag bin; 2. high-chlorine electric field dust removal ash bin; 3. disc pelletizing machine; 4. iron ore bin; 5. fuel bin; 6. flux bin; 7. iron-containing dust slag bin; 8. first drum mixer; 9. second drum mixer; 10. sintering trolley; 11. flue; 12. sintering fan; 13. electrostatic precipitator; 14. dust removal fan; 15. desulfurization equipment; 16. desulfurization induced draft fan; 17. denitrification equipment; 18. denitrification induced draft fan; 19. chimney. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0042] The present invention provides a method for removing dioxins by utilizing electrolytic manganese slag, comprising the following steps:

[0043] S1: mixing iron ore, fuel, flux and iron-containing dust to prepare a first mixed material;

[0044] The iron-containing dust slag contains low-chlorine electric field dust removal ash, and the chlorine content of the low-chlorine electric field dust removal ash is 2% to 10%;

[0045] S2: mixing electrolytic manganese slag with high-chlorine electric field dust removal ash to obtain a second mixed material;

[0046] The chlorine content in the high-chlorine electric field dust removal ash is greater than 10%;

[0047] S3: mixing the first mixed material and the second mixed material, and then sintering the mixed material to generate dust and waste gas;

[0048] S4: Detect the toxic equivalent concentration of dioxins in the waste gas. When the toxic equivalent concentration of dioxins is ≤0.5ng-TEQ / m 3 Discharge at the time.

[0049] Compared with the prior art, in order to reduce production costs and save resources, the present invention adds electric field dust removal ash as return material, and can recycle iron and carbon elements in the electric field dust removal ash. However, the electric field dust removal ash contains chlorine, which is one of the elements that form dioxins. Therefore, the present invention mixes the electric field dust removal ash with a chlorine content greater than 10% as high-chlorine electric field dust removal ash with electrolytic manganese slag, and adds the electric field dust removal ash with a chlorine content of 2% to 10% as low-chlorine electric field dust removal ash to iron-containing dust slag for mixing, thereby reducing the contact between chlorine and hydrocarbons and reducing the generation of dioxins.

[0050] In addition, the present invention utilizes electrolytic manganese slag to catalytically degrade dioxins produced during iron ore sintering, and produces carbon dioxide, hydrogen chloride and water after degradation, thereby achieving efficient removal of dioxins and recycling of electrolytic manganese slag and electric field dust removal ash.

[0051] Specifically, in terms of mass percentage, the iron ore is 70% to 85%, the fuel is 6% to 9%, the flux is 9% to 15%, and the iron-containing dust slag is 5% to 15%. The low-chlorine electric field dust removal ash accounts for 15% to 35% of the iron-containing dust slag. Among them, the iron ore is a mixed ore of various iron ores. The fuel is coal powder or coke powder. The flux is selected from dolomite, limestone and quicklime. The iron-containing dust slag is various dusts and slags generated in the production process of steel enterprises, such as sintering electric field dust removal ash, blast furnace gravity dust removal ash, steel slag and steel slag tailings (products after steel slag iron selection). Steel enterprises usually use this part of the iron-containing dust slag by returning it to the iron ore sintering batching process, in order to realize the utilization of elements such as iron and calcium in the iron-containing dust slag.

[0052] It should be noted that in order to make the material mixing more uniform, the sintering more complete, and the electrolytic manganese slag more efficient in degrading dioxins, it is necessary to control the particle size of electrolytic manganese slag and dust ash, among which the particle size of low-chlorine electric field dust ash <38μm accounts for <65%, the particle size of high-chlorine electric field dust ash <38μm accounts for >90%, and the particle size of electrolytic manganese slag <30μm accounts for >85%, and the MnO in electrolytic manganese slag accounts for >10%. x The content is 8% to 10%.

[0053] It should be noted that in order to more efficiently catalyze and degrade dioxins produced during the sintering process, the toxic equivalent concentration of dioxins should be ≤0.5ng-TEQ / m 3 , in line with national emission standards. Therefore, it is necessary to adjust the ratio of electrolytic manganese slag to high chlorine electric field dust removal ash, and control the mass of electrolytic manganese slag to be 10 to 30 times that of high chlorine electric field dust removal ash; when the mass of electrolytic manganese slag is higher than 30 times that of high chlorine electric field dust removal ash, it will deteriorate the permeability of the sintering material layer, affect the quality of sintered ore, and increase the cost of dioxin treatment; when the mass of electrolytic manganese slag is lower than 10 times that of high chlorine electric field dust removal ash, it will affect the granulation effect of electrolytic manganese slag and high chlorine electric field dust removal ash, and weaken the catalytic removal effect of dioxins in the sintering process.

[0054] In the catalytic degradation reaction of dioxins by electrolytic manganese slag, the electrolytic manganese slag contains MnO x It plays a major role in catalyzing the degradation of dioxins in the iron ore sintering process. x (such as MnO 2 , Mn 2 O 5 ) is converted into low-cost MnO x (such as MnO, Mn 2 O 3 ), and in the subsequent reaction process and subsequent dust removal and transportation process, most of the low-priced MnO x It is then oxidized to high-valent MnOx , the catalytic activity is restored and it can continue to participate in the reaction, so the amount of electrolytic manganese slag added can be appropriately reduced, saving the cost of dioxin treatment in sintering flue gas.

[0055] Specifically, the present invention provides a method for removing dioxins by using electrolytic manganese slag, comprising the following steps:

[0056] Step 1, adding iron ore, fuel, flux and iron-containing dust into a first drum mixer according to a certain ratio to prepare a first mixture, and adding water to mix;

[0057] Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation;

[0058] Step 3, mixing electrolytic manganese slag and high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation;

[0059] Step 4, mixing the granulated first mixed material and the second mixed material in a corresponding proportion, and then evenly spreading them on a sintering trolley for sintering to generate sintering fume;

[0060] Step 5: The sintering flue gas enters the dust collector for dust removal under the action of the dust removal fan, generating dust removal ash and waste gas;

[0061] Step 6: After desulfurization and denitrification treatment, the exhaust gas can be discharged through a chimney to meet the emission standards.

[0062] Compared with the prior art, the present invention adds water to the first mixed material and the second mixed material respectively and then granulates them, and then evenly lays them on the sintering trolley according to the corresponding proportion for sintering. During the sintering process, sintering flue gas is generated, and the sintering flue gas contains a certain concentration of dust and dioxins; the second mixed material contains electrolytic manganese slag, and the electrolytic manganese slag continuously catalyzes and degrades dioxins. As the whole working process proceeds, the uncatalyzed dioxins in the sintering flue gas enter the dust collector and continue to be catalytically degraded, generating dust ash and waste gas; finally, the waste gas is discharged through a chimney after desulfurization and denitrification treatment, and the toxic equivalent concentration of dioxins in the waste gas is less than 0.1ng-TEQ / m 3 ; Dust emission concentration <20mg / m 3 .

[0063] Specifically, in step 1, the mixing time is 2 to 5 minutes, the speed of the first drum mixer is 4 to 6 r / min, and the amount of water added is 75% to 90% of the total water amount, wherein the total water amount is controlled at 6% to 8% of the mixture amount.

[0064] Specifically, in step 2, the mixing time is controlled at 3 to 6 minutes, the speed of the second drum mixer is 5 to 9 r / min, the amount of water added is 10% to 25% of the total water amount, and the mass of the balls with a particle size of 3 to 5 mm accounts for 40% to 60% of the total ball proportion.

[0065] Specifically, the mixing time of step 3 is 6 to 8 minutes, the radius of the disc ball making machine is 2 to 4 meters, the rotation speed is 4 to 6 r / min, the inclination angle is 45° to 50°, and the mass of the balls with a particle size of 5 to 8 mm accounts for 60% to 80% of the total ball proportion.

[0066] Specifically, in step 3, the amount of water added is controlled to be 8% to 10% of the mass of the second mixture.

[0067] Specifically, in step 4, the thickness of the sintering mixture is 700-1000 mm, the sintering flue gas temperature is 150-250° C., and the flue gas volume is 1×10 6 ~1.3×10 6 m 3 / h, the dust concentration in the flue gas is 0.5~4g / m 3 .

[0068] Specifically, in step 5, the sintering flue gas temperature is reduced to 100-200°C.

[0069] It should be noted that in order to realize the above-mentioned method for removing dioxins, the present invention provides a device. Figure 1 The device includes an electrolytic manganese slag bin 1, a high-chlorine electric field dust removal ash bin 2, a disc pelletizer 3, an iron ore bin 4, a fuel bin 5, a flux bin 6, an iron-containing dust slag bin 7, a first drum mixer 8, a second drum mixer 9, a sintering trolley 10, a flue 11, a sintering fan 12, an electrostatic precipitator 13, a dust removal fan 14, a desulfurization equipment 15, a desulfurization induced draft fan 16, a denitrification equipment 17, a denitrification induced draft fan 18 and a chimney 19.

[0070] The electrolytic manganese slag bin 1, high-chlorine electric field dust removal ash bin 2, iron ore bin 4, fuel bin 5, flux bin 6 and iron-containing dust slag bin 7 are independently arranged and used to store electrolytic manganese slag, high-chlorine electric field dust removal ash, iron ore, fuel, flux and iron-containing dust slag respectively; the electrolytic manganese slag and high-chlorine electric field dust removal ash are mixed and added to the disc pelletizing machine 3 to obtain a second mixture; the iron ore, fuel, flux and iron-containing dust slag are mixed and added to the first drum mixer 8, and then added to the second drum mixer 9 to obtain a first mixture; the first mixture and the second mixture are spread on the sintering trolley 10 for sintering.

[0071] Sintering flue gas is generated during the sintering process and is collected in the flue 11. The sintering flue gas in the flue 11 is made to flow along the pipeline to the electrostatic precipitator 13 through the sintering fan 12, and dust and waste gas are generated in the electrostatic precipitator 13. The waste gas passes through the dust removal fan 14 along the pipeline into the desulfurization equipment 15 for desulfurization treatment, and then passes through the desulfurization induced draft fan 16 along the pipeline into the denitrification equipment 17 for denitrification treatment, and finally the waste gas after desulfurization and denitrification treatment is discharged into the chimney 19 through the denitrification induced draft fan 18 for discharge.

[0072] The existing electrostatic precipitator 13 can classify the dust ash into low-chlorine electric field dust ash and high-chlorine electric field dust ash, and can also be divided into multiple levels, which will not be repeated in the present invention. When the chlorine content of the low-chlorine electric field dust ash is 2% to 10%, it is returned to the iron-containing dust slag bin 7 for continued use; when the chlorine content of the high-chlorine electric field dust ash is greater than 10%, it is returned to the high-chlorine electric field dust ash bin 2 and continues to be mixed with the electrolytic manganese slag.

[0073] When the electrostatic precipitator is working, the electrolytic manganese slag and dust particles are in a high-voltage electrostatic field, and collide with the positive and negative ions and electrons between the electrodes to become charged. The electrolytic manganese slag and dust particles carrying electrons and ions move toward the opposite electrode under the action of the electric field force and accumulate on the opposite electrode. The dust on the electrode falls into the collection hopper through vibration and other methods. In the electrostatic precipitator, the electrolytic manganese slag comes into contact with the sintering flue gas, realizing the secondary catalytic degradation of dioxins by the electrolytic manganese slag, and further removing dioxins.

[0074] Specifically, a pneumatic conveying fan and another electrolytic manganese slag bin are connected to the pipeline connecting the flue 11 and the sintering fan 12. The pneumatic conveying fan sprays the electrolytic manganese slag in the electrolytic manganese slag bin into the pipeline to catalyze the degradation of dioxins in the sintering flue gas, thereby further reducing the dioxin content.

[0075] In order to explain the present invention clearly, it is illustrated by the following examples and comparative examples.

[0076] The present invention uses 360m 2 The sintering trolley is taken as an example for explanation, and the sources of various raw materials are shown in Table 1.

[0077] Table 1 Sources of raw materials

[0078]

[0079] *The proportion of low-chlorine dust removal ash in iron-containing dust slag is 15% to 35%.

[0080] Example 1

[0081] The present invention provides a method for removing dioxins by utilizing electrolytic manganese slag, comprising the following steps:

[0082] Step 1: Add iron ore, fuel, flux and iron-containing dust into the first drum mixer according to the proportions in Table 1 to obtain 3.0×10 5 kg of the first mixture, and then add water to mix;

[0083] The mixing time is 5 min, the speed is 5 r / min, and the amount of water added is 75% of the total water amount, wherein the total water amount is controlled at 7% of the sintering mixture amount;

[0084] The iron-containing dust slag contains 20% of low-chlorine electric field dust removal ash and 5% of chlorine; the low-chlorine electric field dust removal ash has a particle size of less than 38 μm and 50% of the particle size;

[0085] Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation;

[0086] The granulation time is 6 minutes, the rotation speed is 6 r / min, and the amount of water added is 25% of the total water amount; in the sintered mixed material balls after granulation, the material balls with a particle size of 3 to 5 mm account for 50%, and the moisture content of the material balls is 7%;

[0087] Step 3, mixing electrolytic manganese slag and high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation;

[0088] Among them, the proportion of the selected electrolytic manganese slag with a particle size of less than 30 μm is 90%, of which MnO x The content is about 8%;

[0089] The radius of the disc pelletizing machine is 3m, the pelletizing time is 7min, the rotation speed is 5r / min, and the inclination angle is 45°; among the mixed balls after granulation, the balls with a particle size of 5-8mm account for 70%, and the moisture content of the balls is 9%.

[0090] Step 4: 3.0×10 5 kg, second mixed material 2.0×10 4 kg are mixed and then evenly spread on the sintering trolley for sintering to generate sintering fume;

[0091] The paving thickness is 800 mm, the flue gas temperature is about 200 °C, and the flue gas volume is about 1.20 × 10 6 m 3 / h, the dust concentration in the flue gas is about 3g / m 3 The toxic equivalent concentration of dioxins in flue gas is about 0.2ng-TEQ / m 3 ;

[0092] At this time, the electrolytic manganese slag catalyzes the degradation of dioxins in the flue gas, and the reaction equation is expressed as:

[0093] Step 5: The sintering flue gas enters the dust collector from the flue through the pipeline under the action of the dust removal fan, and undergoes dust removal treatment to generate dust removal ash and waste gas;

[0094] In the electrostatic precipitator, the temperature of the sintering flue gas is 150°C, and the dust still contains about 1% MnO x The remaining undegraded dioxins in the sintering flue gas are further catalytically degraded with the dust removal ash;

[0095] Step 6: After desulfurization and denitrification, the waste gas can be discharged through the chimney to meet the emission standards; after testing, the toxic equivalent concentration of dioxins in the waste gas is less than 0.1ng-TEQ / m 3 , less than 0.5ng-TEQ / m 3 The national emission standard; the dust emission concentration is less than 20mg / m 3 , less than 30mg / m 3 national emission standards.

[0096] Example 2

[0097] The present invention provides a method for removing dioxins by utilizing electrolytic manganese slag, comprising the following steps:

[0098] Step 1: Add iron ore, fuel, flux and iron-containing dust into the first drum mixer according to the proportions in Table 1 to obtain 3.2×10 5 kg of the first mixture, and then add water to mix;

[0099] The mixing time is 4 minutes, the speed is 6 r / min, and the amount of water added is 70% of the total water amount, and the total water amount is controlled at 7.5% of the sintering mixture;

[0100] The iron-containing dust slag contains 25% of low-chlorine electric field dust removal ash and 6% of chlorine; the low-chlorine electric field dust removal ash has a particle size of less than 38 μm and accounts for 55%;

[0101] Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation;

[0102] The granulation time is 5 minutes, the rotation speed is 7 r / min, and the amount of water added is 30% of the total amount of water added; among the sintered mixed balls after granulation, the ball size of 3-5 mm accounts for 55%, and the moisture content of the ball is 7.5%;

[0103] Step 3, mixing the electrolytic manganese slag and the high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation;

[0104] Among them, the proportion of the selected electrolytic manganese slag with a particle size of less than 30 μm is 86%, of which MnO x The content is about 8.5%;

[0105] The radius of the disc pelletizing machine is 3.5m, the pelletizing time is 6min, the rotation speed is 4r / min, and the inclination angle is 46°; among the mixed balls after granulation, the balls with a particle size of 5-8mm account for 65%, and the moisture content of the balls is 8.5%.

[0106] Step 4: 3.2×10 5 kg, second mixed material 2.5×10 4 kg are mixed and then evenly spread on the sintering trolley for sintering to generate sintering fume;

[0107] The paving thickness is 850 mm, the flue gas temperature is about 220 °C, and the flue gas volume is about 1.1 × 10 6 m 3 / h, the dust concentration in the flue gas is about 2.5g / m 3 The toxic equivalent concentration of dioxins in flue gas is about 0.22ng-TEQ / m 3 ;

[0108] At this time, the electrolytic manganese slag catalyzes the degradation of dioxins in the flue gas, and the reaction equation is expressed as:

[0109] Step 5: The sintering flue gas enters the dust collector from the flue through the pipeline under the action of the dust removal fan, and undergoes dust removal treatment to generate dust removal ash and waste gas;

[0110] In the electrostatic precipitator, the temperature of the sintering flue gas is 160°C, and the dust still contains about 1.5% MnO x The remaining undegraded dioxins in the sintering flue gas are further catalytically degraded with the dust removal ash;

[0111] Step 6: After desulfurization and denitrification, the waste gas can be discharged through the chimney to meet the emission standards; after testing, the toxic equivalent concentration of dioxins in the waste gas is less than 0.1ng-TEQ / m 3 , less than 0.5ng-TEQ / m 3 The national emission standard; the dust emission concentration is less than 15mg / m 3 , less than 30mg / m 3 national emission standards.

[0112] Example 3

[0113] The present invention provides a method for removing dioxins by utilizing electrolytic manganese slag, comprising the following steps:

[0114] Step 1: Add iron ore, fuel, flux and iron-containing dust into the first drum mixer according to the proportions in Table 1 to prepare 3.5×10 5 kg of the first mixture, and then add water to mix;

[0115] The mixing time is 4.5min, the speed is 4r / min, and the amount of water added is 80% of the total water amount, wherein the total water amount is controlled at 8% of the sintering mixture amount;

[0116] The iron-containing dust slag contains 30% of low-chlorine electric field dust removal ash and 7% of chlorine; the low-chlorine electric field dust removal ash has a particle size of less than 38 μm and 60% of the particle size;

[0117] Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation;

[0118] The granulation time is 4 minutes, the rotation speed is 8 r / min, and the amount of water added is 20% of the total water amount; among the sintered mixed balls after granulation, the ball size of 3-5 mm accounts for 58%, and the moisture content of the ball is 8%;

[0119] Step 3, mixing electrolytic manganese slag and high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation;

[0120] Among them, the proportion of the selected electrolytic manganese slag with a particle size of less than 30 μm is 87%, of which MnO x The content is about 9%;

[0121] The radius of the disc pelletizing machine is 4m, the pelletizing time is 6.5min, the rotation speed is 6r / min, and the inclination angle is 47°; among the mixed balls after granulation, the balls with a particle size of 5-8mm account for 75%, and the moisture content of the balls is 8%.

[0122] Step 4: 3.5×10 5 kg, second mixed material 2.2×10 4 kg are mixed and then evenly spread on the sintering trolley for sintering to generate sintering fume;

[0123] The paving thickness is 900 mm, the flue gas temperature is about 230 °C, and the flue gas volume is about 1.25 × 10 6 m 3 / h, the dust concentration in the flue gas is about 3.2g / m 3The toxic equivalent concentration of dioxins in flue gas is about 0.21ng-TEQ / m 3 ;

[0124] At this time, the electrolytic manganese slag catalyzes the degradation of dioxins in the flue gas, and the reaction equation is expressed as:

[0125] Step 5: The sintering flue gas enters the dust collector from the flue through the pipeline under the action of the dust removal fan, and undergoes dust removal treatment to generate dust removal ash and waste gas;

[0126] In the electrostatic precipitator, the temperature of the sintering flue gas is 170°C, and the dust still contains about 2% MnO x The remaining undegraded dioxins in the sintering flue gas are further catalytically degraded with the dust removal ash;

[0127] Step 6: After desulfurization and denitrification, the waste gas can be discharged through the chimney to meet the emission standards; after testing, the toxic equivalent concentration of dioxins in the waste gas is less than 0.1ng-TEQ / m 3 , less than 0.5ng-TEQ / m 3 The national emission standard; the dust emission concentration is less than 18mg / m 3 , less than 30mg / m 3 national emission standards.

[0128] Comparative Example 1

[0129] The steps of removing dioxins in Comparative Example 1 are substantially the same as those in Example 1, except that:

[0130] In comparative example 1, the electrolytic manganese slag is replaced with manganese-containing tailings. Specifically, the manganese-containing tailings have a particle size of 0.074 to 0.5 mm, accounting for 70% of the total particle size. x The content is 2%.

[0131] According to the test, the toxic equivalent concentration of dioxins in the exhaust gas is greater than 0.15ng-TEQ / m 3 ; Dust emission concentration >20mg / m 3 .

[0132] Comparative Example 2

[0133] The steps of removing dioxins in Comparative Example 2 are substantially the same as those in Example 2, except that in Comparative Example 1, the electrolytic manganese slag is replaced with manganese-containing tailings. Specifically, the manganese-containing tailings have a particle size of 0.074 to 0.5 mm, accounting for 75% of the total particle size. x The content is 1.5%.

[0134] According to the test, the toxic equivalent concentration of dioxins in the exhaust gas is greater than 0.18ng-TEQ / m 3; Dust emission concentration>15mg / m 3 .

[0135] Comparative Example 3

[0136] The steps of removing dioxins in Comparative Example 3 are substantially the same as those in Example 3, except that in Comparative Example 3, no electrolytic manganese slag is added for sintering.

[0137] According to the test, the toxic equivalent concentration of dioxins in the exhaust gas is greater than 0.2ng-TEQ / m 3 ; Dust emission concentration >18mg / m 3 .

[0138] By testing the toxic equivalent concentration of dioxins in the sintering flue gas after degradation and the dust emission concentration, the dioxins removed from iron ore sintering by the methods provided in Examples 1-3 all meet the national emission standards, or even are lower than the national emission standards, wherein the toxic equivalent concentration of dioxins is less than 0.1 ng-TEQ / m 3 ; Dust emission concentration <20mg / m 3 .

[0139] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for removing dioxins using electrolytic manganese slag, characterized in that: The following steps are involved: S1: mixing iron ore, fuel, flux and iron-containing dust to prepare a first mixed material; The iron-containing dust slag contains low-chlorine electric field dust removal ash, the chlorine content of the low-chlorine electric field dust removal ash is 2% to 10%, and the proportion of particles with a diameter of less than 38 μm in the low-chlorine electric field dust removal ash is less than 65%; S2: mixing electrolytic manganese slag with high-chlorine electric field dust removal ash, wherein the mass ratio of the electrolytic manganese slag to the high-chlorine electric field dust removal ash is 10 to 30, to obtain a second mixed material; The chlorine content in the high-chlorine electric field dust removal ash is greater than 10%, the proportion of the high-chlorine electric field dust removal ash with a particle size of less than 38 μm is greater than 90%, the proportion of the electrolytic manganese slag with a particle size of less than 30 μm is greater than 85%, and the MnO in the electrolytic manganese slag is greater than 10%. x The content is 8% to 10%; S3: mixing the first mixed material and the second mixed material, and then sintering the mixed material to generate dust and waste gas; S4: Detect the toxic equivalent concentration of dioxins in the waste gas. When the toxic equivalent concentration of dioxins is ≤0.5ng-TEQ / m 3 Discharge at the time.

2. The method for removing dioxins by electrolytic manganese slag according to claim 1, characterized in that: In step S1, in terms of mass percentage, the iron ore is 70% to 85%, the fuel is 6% to 9%, the flux is 9% to 15%, and the iron-containing dust is 5% to 15%.

3. The method for removing dioxins by electrolytic manganese slag according to claim 1, characterized in that: In step S3, the mass ratio of the second mixed material to the first mixed material is 0.05-0.

2.

4. The method for removing dioxins by electrolytic manganese slag according to claim 1, characterized in that: In step S3, when the chlorine content in the dust removal ash is ≤10%, it is returned to the iron-containing dust slag; when the chlorine content in the dust removal ash is greater than 10%, it is returned to the electrolytic manganese slag.

5. The method for removing dioxins by electrolytic manganese slag according to claim 1, characterized in that: The toxic equivalent concentration of dioxins in the waste gas is less than 0.1ng-TEQ / m 3 ; Dust concentration <20mg / m 3 .

6. The method for removing dioxins by electrolytic manganese slag according to claim 1, characterized in that: The following steps are involved: Step 1, adding iron ore, fuel, flux and iron-containing dust into a first drum mixer according to a certain ratio to prepare a first mixture, and adding water to mix; Step 2, adding the first mixed material into a second drum mixer, and adding water for granulation; Step 3, mixing the electrolytic manganese slag and the high-chlorine electric field dust removal ash in a certain ratio to obtain a second mixture, adding the second mixture into a disc pelletizing machine, and adding water for granulation; Step 4, mixing the granulated first mixed material and the second mixed material in a corresponding proportion, and then evenly spreading them on a sintering trolley for sintering to generate sintering fume; Step 5: The sintering flue gas enters the electrostatic precipitator for dust removal under the action of the dust removal fan, generating electric field dust removal ash and waste gas; Step 6: After desulfurization and denitrification treatment, the exhaust gas can be discharged through a chimney to meet the emission standards.

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