CN110201512A - A kind of method and apparatus of flue gas desulfurization and denitrification - Google Patents

Abstract

The invention relates to the technical field of flue gas treatment, in particular to a method and device for flue gas desulfurization and denitrification. The present invention provides a flue gas desulfurization and denitrification method. In the present invention, part of the red mud is mixed with water, and then the flue gas to be treated is subjected to the first desulfurization and denitrification treatment, and then the first slurry obtained after the reaction is subjected to precipitation treatment to obtain The supernatant is mixed with the remaining red mud for the second desulfurization and denitrification treatment. While improving the desulfurization and denitrification effect, the utilization rate of the red mud is improved and the production cost is reduced; the flue gas after the first desulfurization and denitrification treatment is combined with Ozone is mixed, using ozone to oxidize the insoluble NO into water-soluble NO ₂ and N ₂ O ₅ , and then perform the second desulfurization and denitrification, which effectively improves the desulfurization and denitrification effect, and the total desulfurization effect is as high as 95%. The total denitrification efficiency is 60-80%.

Description

A method and device for flue gas desulfurization and denitrification

technical field

The invention relates to the technical field of flue gas treatment, in particular to a method and device for flue gas desulfurization and denitrification.

Background technique

Red mud is a kind of waste residue discharged during the production of alumina using bauxite as raw material. It is estimated that about 1 to 1.5 tons of red mud is produced for every 1 ton of alumina produced, and nearly 120 million tons of red mud are produced every year. In 2017 The global cumulative discharge of red mud reaches about 3.9 billion tons. At present, most of the ways to dispose of red mud are open-air storage. Due to the fine particle size and strong alkalinity (pH value of 10-13) of red mud, it is easy to cause air pollution after being air-dried, and the surrounding soil will be polluted by rainwater. Alkalinization, and then seeping into groundwater, brings safety hazards to the growth of animals and plants. Therefore, realizing the reuse of red mud has attracted more and more attention from researchers.

As we all know, SO ₂ and NO _x produced in industry can cause photochemical smog and _acid rain, which are the main factors causing air pollution. Simultaneous denitrification has rarely been reported. Chinese patent CN109224820A introduces a method for ozone oxidation and denitrification of boiler flue gas, but this method needs to provide an absorption liquid composed of magnesium sulfite and potassium permanganate, which increases the cost, and this method can only achieve denitrification of flue gas. The desulfurization effect is not good.

Contents of the invention

The object of the present invention is to provide a method and device for flue gas desulfurization and denitrification. The present invention utilizes the combination of red mud and ozone, which not only improves the desulfurization and denitrification efficiency of flue gas, but also realizes the reuse of red mud, reducing production It has good economic and environmental benefits.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a method for flue gas desulfurization and denitrification, comprising the following steps:

Mix part of the red mud with water to obtain the initial slurry;

The initial slurry is mixed with the flue gas to be treated, and the first desulfurization and denitrification treatment is performed to obtain the first slurry and the first flue gas;

Precipitating the first slurry to obtain a supernatant;

mixing the supernatant with the remaining red mud to obtain a second slurry;

mixing the first flue gas with ozone to undergo an oxidation reaction to obtain a second flue gas;

The second slurry is mixed with the second flue gas, the second desulfurization and denitrification treatment is performed, and the obtained third flue gas is discharged.

Preferably, the mass ratio of the part of red mud to water is 1:(10-40).

Preferably, the particle size of the partial red mud and the remaining red mud are independently 100-300 mesh.

Preferably, the liquid-gas ratio of the initial slurry to the flue gas to be treated is 1-10 L/m ³ .

Preferably, the time for the precipitation treatment is 6-10 hours.

Preferably, the molar ratio of NO to ozone in the first flue gas is 1:(1-1.8).

Preferably, the liquid-gas ratio of the second slurry to the second flue gas is 1-6L/ ^m3

Preferably, the first slurry is subjected to precipitation treatment to obtain a lower layer slurry; the lower layer slurry is used as a raw material for preparing ceramic materials;

A third slurry is also obtained after the second desulfurization and denitrification treatment, and the iron in the third slurry is recovered by magnetic separation to obtain a red mud slurry; the red mud slurry is used as a raw material for preparing ceramic materials.

The invention provides a flue gas desulfurization and denitrification device, comprising

slurry tank 9;

The first spray tower 2 communicated with the outlet of the slurry tank 9;

A settling tank 8 communicated with the first slurry outlet of the first spray tower 2;

A circulating slurry tank 12 communicated with the water outlet of the settling tank 8;

The second spray tower 11 communicated with the outlet of the circulating slurry tank 12;

The second spray tower 11 communicates with the first flue gas outlet of the first spray tower 2;

An ozone generator 10 is arranged between the first spray tower 2 and the second spray tower 11;

The ozone outlet of the ozone generator 10 communicates with the flue gas pipeline between the first spray tower 2 and the second spray tower 11 .

Preferably, it also includes a first stirring device 3-1 and a second stirring device 3-2, the first stirring device 3-1 is arranged at the bottom inside the first spray tower 2; the second stirring device 3-2 is arranged at the bottom inside the second spray tower 11.

The invention provides a method for flue gas desulfurization and denitrification, comprising the following steps: mixing part of the red mud with water to obtain an initial slurry; mixing the initial slurry with the flue gas to be treated to perform the first desulfurization and denitrification treatment , to obtain the first slurry and the first flue gas; the first slurry is subjected to precipitation treatment to obtain a supernatant; the supernatant is mixed with the remaining red mud to obtain a second slurry; the first flue gas Gas and ozone are mixed, oxidation reaction occurs, and the second flue gas is obtained; the second slurry is mixed with the second flue gas, and the second desulfurization and denitrification treatment is performed to obtain the third slurry and the third flue gas, The obtained third flue gas is discharged. In the present invention, part of the red mud is first mixed with water, and then the flue gas to be treated is desulfurized and denitrified for the first time, and then the first slurry obtained after the reaction is subjected to precipitation treatment, and the obtained supernatant is mixed with the remaining red mud for the second The secondary desulfurization and denitrification treatment improves the utilization rate of red mud and reduces the production cost while improving the desulfurization and denitrification effect; the flue gas after the first desulfurization and denitrification treatment is mixed with ozone, and the insoluble NO in water is oxidized by ozone NO ₂ and N ₂ O ₅ which are easily soluble in water, and then carry out the second desulfurization and denitrification effect, which effectively improves the desulfurization and denitrification effect. The total desulfurization effect is as high as 95%, and the total denitrification efficiency is 60-80%. In addition, in the present invention, the lower layer slurry obtained after the first slurry is subjected to precipitation treatment and the third slurry can be used to prepare ceramic materials after treatment, so as to realize the maximum utilization of resources, which has important environmental protection significance.

The invention provides a flue gas desulfurization and denitrification device. The device provided by the invention has reasonable configuration of each processing unit, stable operation, high degree of automation, good desulfurization and denitrification effect, and is suitable for large-scale treatment of flue gas.

Description of drawings

Fig. 1 is a schematic structural diagram of a flue gas desulfurization and denitrification device provided by the present invention. In the figure, 1-the inlet of flue gas to be treated, 2-the first spray tower, 3-1-the first stirring device, 3-2-the second Stirring device, 4-1-first spraying device, 4-2-second spraying device, 5-1-first circulating pump, 5-2-second circulating pump, 5-3-third circulating pump, 6-Second flue gas inlet, 7-1-Third spraying device, 7-2-Fourth spraying device, 8-Sedimentation tank, 9-Slurry tank, 10-Ozone generator, 11-Second spraying Tower, 12-cycle slurry tank.

Detailed ways

The invention provides a method for flue gas desulfurization and denitrification, comprising the following steps:

Mix part of the red mud with water to obtain the initial slurry;

The initial slurry is mixed with the flue gas to be treated, and the first desulfurization and denitrification treatment is performed to obtain the first slurry and the first flue gas;

Precipitating the first slurry to obtain a supernatant;

mixing the supernatant with the remaining red mud to obtain a second slurry;

mixing the first flue gas with ozone to undergo an oxidation reaction to obtain a second flue gas;

The second slurry is mixed with the second flue gas, and a second desulfurization and denitration treatment is performed to obtain a third slurry and a third flue gas, and the obtained third flue gas is discharged.

In the invention, part of the red mud is mixed with water to obtain initial slurry. In the present invention, the red mud is preferably waste slag produced in the process of producing alumina, and in a specific embodiment of the present invention, Bayer process red mud produced by aluminum and magnesium plants is preferably used. In the present invention, the particle size of the red mud is preferably 100-300 mesh, more preferably 200-300 mesh. In a specific embodiment of the present invention, if the particle size of the commercially available red mud is too large, it is preferable to use the red mud with a suitable particle size after ball milling. In the present invention, it is preferred to ball mill commercially available red mud to obtain red mud with a suitable particle size, then take part of the red mud for the first desulfurization and denitrification, and the remaining red mud for the subsequent second desulfurization and denitrification. In the present invention, there is no special limitation on the mass ratio of the part of the red mud to the remaining red mud, and it is better to obtain the initial slurry and the second slurry that meet the pH value requirements.

In the present invention, the source of the water is not particularly limited, and industrial water is preferably used. In the present invention, there is no special limitation on the mixing method of the part of the red mud and water, and a conventional mixing method in the field can be used. In the present invention, the mass ratio of the part of red mud to water is preferably 1:(10-40), more preferably 1:20.

After the initial slurry is obtained, the present invention mixes the initial slurry with the flue gas to be treated, performs the first desulfurization and denitrification treatment, and obtains the first slurry and the first flue gas. In the present invention, the liquid-gas ratio of the initial slurry to the flue gas to be treated is preferably 1-10 L/m ³ , more preferably 6 L/m ³ . The invention increases the gas-liquid contact area by increasing the liquid-gas ratio, and can promote the absorption of SO ₂ and NO _x by the initial slurry. In the present invention, the flue gas to be treated is preferably petroleum coke calcined flue gas, and the temperature of the flue gas to be treated is preferably 150°C to 200°C, more preferably 160°C; the flow rate of the flue gas to be treated is preferably 1.8-2.5m ³ /h, more preferably 2.2m ³ /h; the concentration of SO ₂ in the flue gas to be treated is preferably 1500-3500mg/m ³ , more preferably 3000mg/m ³ ; the concentration of NO Preferably it is 200-500 mg/m ³ , more preferably 400 mg/m ³ .

In the present invention, the mixing method is preferably to spray the initial slurry onto the flue gas to be treated, so as to increase the contact area between the initial slurry and the flue gas, thereby increasing the desulfurization and denitrification efficiency.

In the process of the first desulfurization and denitrification treatment, the present invention performs the first desulfurization and denitrification treatment on the flue gas to be treated, and the reactions that occur mainly include:

SO ₂ +H ₂ O→H ₂ SO ₃ ;

Al ₂ O ₃ +3H ₂ SO ₃ →Al ₂ (SO ₃ ) ₃ +3H ₂ O;

Na2O _{+ H2SO3 →} Na2SO3 _{+ H2O ;}

CaO+ _{H2SO3 →} CaSO3 _{+ H2O} ;

3NO ₂ +H ₂ O → 2HNO ₃ +NO.

Among them, alumina, sodium oxide and calcium oxide all come from red mud. In the process of the first desulfurization and denitrification treatment in the present invention, the pH value of the obtained slurry will drop, and when the pH value of the obtained slurry drops below 5, the present invention preferably discharges part of the slurry as the first slurry for subsequent precipitation treatment , while replenishing the same volume of initial slurry. In the present invention, the first slurry preferably accounts for 30-60% of the total volume of the slurry obtained from the first desulfurization and denitrification treatment.

In the present invention, the first slurry is subjected to precipitation treatment to obtain a supernatant. In the present invention, the method of the precipitation treatment is preferably static precipitation, and the temperature of the precipitation treatment is preferably 60°C; the time of the precipitation treatment is preferably 6-10 hours.

After obtaining the supernatant, the present invention mixes the supernatant with the remaining red mud to obtain the second slurry. In the present invention, 20-40% of the entire slurry volume is preferably used for mixing with the remaining red mud, and the remaining supernatant remains on the solid precipitate obtained from the precipitation treatment to form a lower layer of slurry for preparing ceramic materials.

The present invention has no special requirements on the mass ratio of the supernatant to the remaining red mud, and it is better to obtain the second slurry with a pH value of 7. The present invention reuses the supernatant in the first slurry for the subsequent second desulfurization and denitrification, which not only reduces the production cost, but also improves the desulfurization and denitrification capacity.

After the first flue gas is obtained, the present invention mixes the first flue gas with ozone for an oxidation reaction to obtain the second flue gas. In the present invention, the molar ratio of NO and ozone in the first flue gas is preferably 1:(1-1.8). In the present invention, the oxidation reaction time is preferably 1.2-1.5s. In the mixing process of the first flue gas and ozone, the present invention uses ozone to oxidize the insoluble NO into water-soluble NO ₂ and N ₂ O ₅ , and then performs the subsequent second desulfurization and denitrification, which can Effectively improve the effect of desulfurization and denitrification.

After the second slurry and the second flue gas are obtained, the present invention mixes the second slurry with the second flue gas, performs a second desulfurization and denitrification treatment, and obtains the third slurry and the third flue gas. In the present invention, the liquid-gas ratio of the second slurry to the second flue gas is preferably 1-6 L/m ³ , more preferably 5 L/m ³ . In the present invention, the mixing method is preferably to spray the second slurry onto the second flue gas to increase the contact area between the second slurry and the flue gas, thereby increasing the desulfurization and denitrification efficiency.

In the present invention, during the second desulfurization and denitration treatment, the second flue gas is subjected to the second desulfurization and denitration treatment, and the reactions that occur mainly include:

SO ₂ +H ₂ O → 2H ⁺ +SO ₃ ^2- ;

N ₂ O ₅ +H ₂ O→2HNO ₃ ;

In the process of the second desulfurization and denitrification treatment, the present invention uses SO ₃ ^2- , HSO ₃ ^- and Fe ³⁺ contained in the supernatant to mix with red mud, and Fe ³⁺ liquid-phase catalytically oxidizes SO ₂ and NO _x dissolve in the liquid phase to form S ⁶⁺ compounds, which enhance the desulfurization and denitrification efficiency. The total desulfurization efficiency of the third flue gas discharged after the second desulfurization and denitrification treatment is as high as 95%, and the total denitrification efficiency reaches 60-80%, which meets the flue gas emission standard and can be discharged directly. In the present invention, the pH value of the third slurry is preferably 4.

After the third slurry is obtained, the present invention preferably uses magnetic separation to recover iron in the third slurry to obtain red mud slurry. In the present invention, the red mud slurry is preferably used as a raw material for preparing ceramic materials, or preferably mixed with the lower layer slurry obtained after the above-mentioned first slurry is subjected to precipitation treatment, and the obtained mixed material is used as a raw material for preparing ceramic materials. In the present invention, the main components of the mixed material are Al ₂ O ₃ , SiO ₂ , etc., which meet the basic conditions for the production of ceramic materials, and after the iron in the slurry is recovered by magnetic separation, the whitening effect of the iron on the porcelain body is avoided. Therefore, the mixed material obtained after desulfurization and denitrification treatment can be used to prepare ceramic materials. While recycling red mud, it turns waste into treasure, which has high economic benefits and environmental protection. benefit.

The invention provides a flue gas desulfurization and denitrification device, comprising

slurry tank 9;

The first spray tower 2 communicated with the outlet of the slurry tank 9;

A settling tank 8 communicated with the first slurry outlet of the first spray tower 2;

A circulating slurry tank 12 communicated with the water outlet of the settling tank 8;

The second spray tower 11 communicated with the outlet of the circulating slurry tank 12;

The second spray tower 11 communicates with the first flue gas outlet of the first spray tower 2;

An ozone generator 10 is arranged between the first spray tower 2 and the second spray tower 11;

The ozone outlet of the ozone generator 10 communicates with the flue gas pipeline between the first spray tower 2 and the second spray tower 11 .

The flue gas desulfurization and denitrification device provided by the present invention includes a slurry tank 9 . In the present invention, the slurry tank 9 is used to mix the part of the red mud and water; the present invention has no special limitation on the slurry tank 9, as long as the mixing process can be ensured to proceed smoothly.

The flue gas desulfurization and denitrification device provided by the present invention includes a first spray tower 2 communicating with the outlet of the slurry tank 9 . In the present invention, the first spray tower 2 is used for the first desulfurization and denitrification treatment; the present invention has no special limitation on the first spray tower 2, which can ensure the desulfurization and denitrification for the first time Processing goes smoothly.

As an embodiment of the present invention, the first spray tower 2 includes a flue gas inlet 1 to be treated, an initial slurry inlet, a first flue gas outlet and a first slurry outlet. As an embodiment of the present invention, the first flue gas outlet is arranged at the top of the first spray tower 2 for discharging the first flue gas; the first slurry outlet is arranged at the first spray tower 2 The bottom of column 2 is used to discharge the first slurry.

As an embodiment of the present invention, the inlet 1 for flue gas to be treated and the inlet for initial slurry are independently arranged on the side of the first spray tower 2 .

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a first spray device 4-1 and a second spray device 4-2, and the first spray device 4-1 and the second spray device The device 4-2 is independently arranged at the top inside the first spray tower 2 and communicated with the initial slurry inlet. As an embodiment of the invention, the first shower device 4-1 and the second shower device 4-2 are arranged up and down. In the present invention, the initial slurry enters the first spraying device 4-1 and the second spraying device 4-2 through the initial slurry inlet, and is sprayed into the flue gas to be treated.

As an embodiment of the present invention, the height of the untreated flue gas inlet 1 is lower than the heights of the first spraying device 4-1 and the second spraying device 4-2. In the present invention, the initial slurry enters the first spraying device 4-1 and the second spraying device 4-2 through the initial slurry inlet, and the untreated flue gas enters the first spraying device through the untreated flue gas inlet 1. In the shower tower 2, the initial slurry flows from top to bottom, and the flue gas to be treated flows from bottom to top, which is beneficial to increase the contact area between the initial slurry and flue gas, and makes the first desulfurization and denitrification treatment more sufficient.

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a first circulation pump 5-1. Into the first spraying device 4-1 and the second spraying device 4-2, the resulting slurry is recycled. The present invention has no special requirements on the number of cycles of the slurry, and it is better when the pH value of the obtained slurry drops below 5, which is beneficial for the lower layer slurry obtained through subsequent precipitation treatment to be used for preparing ceramic materials.

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a first stirring device 3 - 1 , and the first stirring device 3 - 1 is arranged at the bottom inside the first spray tower 2 . The present invention can prevent the red mud particles from settling and accumulating in the first spray tower 2 by means of the stirring device, so as to ensure that the first slurry can be evenly transported to the settling tank.

The flue gas desulfurization and denitrification device provided by the present invention includes a settling tank 8 communicated with the first slurry outlet of the first spray tower 2 . In the present invention, the settling tank 8 is used for the settling treatment; the settling tank 8 is not particularly limited in the present invention, as long as it can ensure the smooth progress of the settling process.

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a second circulation pump 5-2, and the second circulation pump 5-2 is arranged on the first spray tower 2 and the sedimentation tank 8 In between, it is used to transport the first slurry discharged from the first spray tower 2 to the settling tank 8 .

The flue gas desulfurization and denitrification device provided by the present invention includes a circulating slurry tank 12 communicated with the water outlet of the sedimentation tank 8 . In the present invention, the circulating slurry tank 12 is used for mixing the remaining red mud and supernatant; the present invention has no special limitation on the circulating slurry tank 12, as long as the mixing process can be ensured to proceed smoothly.

The flue gas desulfurization and denitrification device provided by the present invention includes a second spray tower 11 communicated with the outlet of the circulating slurry tank 12 . In the present invention, the second spray tower 11 is used for the second desulfurization and denitrification treatment; the present invention has no special limitation on the second spray tower 11, which can ensure the second desulfurization and denitrification Processing goes smoothly.

As an embodiment of the present invention, the second spray tower 11 includes a second flue gas inlet 6, a second slurry inlet, a third flue gas outlet and a third slurry outlet. As an embodiment of the present invention, the third flue gas outlet is arranged at the top of the second spray tower 11 for discharging the third flue gas; the third slurry outlet is arranged at the second spray tower 11 The bottom of column 11 is used to discharge the third slurry.

As an embodiment of the present invention, the second flue gas inlet 6 and the second slurry inlet are independently arranged on the side of the second spray tower 11 .

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a third spraying device 7-1 and a fourth spraying device 7-2, and the third spraying device 7-1 and the fourth spraying device The device 7-2 is independently arranged at the top inside the second spray tower 11 and communicated with the second slurry inlet. As an embodiment of the invention, the third shower device 7-1 and the fourth shower device 7-2 are arranged up and down. In the present invention, the second slurry enters the third spraying device 7-1 and the fourth spraying device 7-2 through the second slurry, and is sprayed into the second flue gas.

As an embodiment of the present invention, the height of the second flue gas inlet 6 is lower than that of the third spraying device 7-1 and the fourth spraying device 7-2. In the present invention, the second slurry enters the third spraying device 7-1 and the fourth spraying device 7-2 through the second slurry inlet, and the second flue gas enters the third spraying device 7-2 through the second flue gas inlet 6 In the second spray tower 11, the second slurry flows from top to bottom, and the second flue gas flows from bottom to top, which is conducive to increasing the contact area between the second slurry and the second flue gas, so that the second desulfurization and denitrification treatment fully carried out.

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a third circulating pump 5-3, and the present invention uses the third circulating pump 5-3 to send the desulfurized and denitrified slurry in the second spray tower 11 to into the third spraying device 7-1 and the fourth spraying device 7-2 to recycle the resulting slurry. In the present invention, there is no special requirement on the number of cycles of the slurry, and it is preferable that the pH value of the obtained slurry is reduced to 4, which is beneficial for the obtained third slurry to be used for preparing ceramic materials.

As an embodiment of the present invention, the flue gas desulfurization and denitrification device further includes a second stirring device 3 - 2 , and the second stirring device 3 - 2 is arranged at the bottom inside the second spray tower 11 . The present invention can prevent the red mud particles from settling and accumulating in the second spray tower 11 by means of the stirring device, so as to ensure the smooth discharge of the third slurry.

In the present invention, the second spray tower 11 communicates with the first flue gas outlet of the first spray tower 2 . In the present invention, the first flue gas discharged from the first spray tower 2 enters the second spray tower 11 for secondary desulfurization and denitration treatment to improve the effect of desulfurization and denitrification.

The flue gas desulfurization and denitration device provided by the present invention includes an ozone generator 10, and the ozone generator 10 is arranged between the first spray tower 2 and the second spray tower 11, and the ozone outlet of the ozone generator 10 It communicates with the flue gas pipeline between the first spray tower 2 and the second spray tower 11 . In the present invention, the ozone generator 10 produces ozone and enters in the flue gas pipeline between the first spray tower 2 and the second spray tower 11, mixes with the first flue gas in the pipeline, and mixes the first The NO in the flue gas is oxidized to NO ₂ and N ₂ O ₅ which are easily soluble in water, thereby improving the denitrification efficiency.

Below in conjunction with Fig. 1, the specific steps of flue gas treatment using the flue gas desulfurization and denitrification device provided by the present invention are described: adding part of the red mud slurry and water to the slurry tank 9 for mixing to obtain the initial slurry; and the flue gas to be treated are sent into the first spray tower 2 for the first desulfurization and denitrification treatment to obtain the first slurry and the first flue gas; the first slurry enters the sedimentation tank 8 for precipitation treatment to obtain the supernatant liquid and the lower layer of slurry; the supernatant and the remaining red mud are added to the circulating slurry tank 12 for mixing to obtain the second slurry; the first flue gas is mixed with the ozone generated by the ozone generator 10, and an oxidation reaction occurs. Obtain the second flue gas; send the second slurry and the second flue gas into the second spray tower 11, and perform the second desulfurization and denitrification treatment to obtain the third slurry and the third flue gas; recover by magnetic separation iron in the third slurry to obtain red mud slurry, mix the red mud slurry with the lower layer slurry obtained after the first slurry is subjected to precipitation treatment, and the obtained mixed material is used to prepare ceramic materials; the third flue gas passes through the chimney discharge.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

In this example, the Bayer process red mud produced by Ningxia Aluminum and Magnesium Factory is used. In terms of mass percentage, the composition of the Bayer process red mud is: CaO 24.7%, Al ₂ O ₃ 23.9%, SiO ₂ 22.38%, Na ₂ O 13.12%, Fe ₂ O ₃ 9.14%, TiO ₂ 3.57%, and unavoidable impurities.

The above-mentioned Bayer process red mud is ball-milled to 100 mesh to 200 mesh, and the ground red mud and industrial water are added to the slurry tank 9 according to the mass ratio of solid-to-liquid ratio of 1:35 for mixing to obtain the initial slurry. The initial slurry Enter the first spray tower 2, spray out through the first spray device 4-1 and the second spray device 4-2, and perform the first desulfurization and denitrification treatment with SO ₂ and NO _x in the flue gas to be treated to obtain The first flue gas and the resulting slurry are transported to the first spraying device 4-1 and the second spraying device 4-2 for recycling through the first circulation pump 5-1. When the pH value of the obtained slurry drops below 5, Discharge 30% to 40% of the slurry as the first slurry for subsequent precipitation treatment, and at the same time replenish the same volume of initial slurry from the slurry tank 9 to the first spray tower ₂ ; wherein, the concentration of SO in the flue gas to be treated is 3000mg /m ³ , the concentration of NO is 400mg/m ³ , the flow rate of flue gas to be treated is 2.2m ³ /h, the temperature is 160°C, and the liquid-gas ratio of initial slurry to industrial flue gas is 6L/m ³ ;

In the sedimentation tank 8, the discharged first slurry was subjected to 7h precipitation treatment, and 30% of the supernatant was taken out and the remaining red mud after grinding was added to the circulating slurry tank 12 for mixing to obtain the second slurry with a pH value of 7 ; The remaining supernatant remains on the solid precipitate obtained from the precipitation treatment to form a lower layer of slurry;

The ozone produced by the ozone generator 10 enters the flue gas pipeline between the first spray tower 2 and the second spray tower 11, mixes with the first flue gas for 1.2s, and oxidizes the NO in the first flue gas into NO ₂ and N ₂ O ₅ to obtain the second flue gas; wherein the molar ratio of the ozone produced by the ozone generator 10 to the NO in the first flue gas is 1;

The above-mentioned second slurry enters the second spray tower 11, is sprayed out by the third spray device 7-1 and the fourth spray device 7-2, and performs the second desulfurization and denitrification treatment with the second flue gas to obtain the third slurry and the third flue gas, wherein the liquid-gas ratio of the second slurry to the second flue gas is 5L/m ³ ;

The obtained slurry is transported to the third spraying device 7-1 and the fourth spraying device 7-2 through the third circulation pump 5-3 for recycling until the pH value of the slurry is 4, and the third slurry is discharged, and the magnetic separation method is used The iron in the third slurry is recovered to obtain a red mud slurry, and the red mud slurry is mixed with the lower layer slurry obtained after the first slurry is subjected to precipitation treatment, and the obtained mixed material is used as a raw material for preparing ceramic materials.

The composition of the third flue gas was detected, and the results showed that the concentration of SO ₂ was 126 mg/m ³ , the concentration of NO _x was 156 mg/m ³ , the desulfurization efficiency was 95.8%, and the denitrification efficiency was 61%.

Example 2

The above-mentioned Bayer process red mud is ball-milled to 200-300 mesh, and the ground red mud and industrial water are added to the slurry tank 9 according to the mass ratio of solid-to-liquid ratio of 1:25 for mixing to obtain the initial slurry. The initial slurry Enter the first spray tower 2, spray out through the first spray device 4-1 and the second spray device 4-2, and perform the first desulfurization and denitrification treatment with SO ₂ and NO _x in the flue gas to be treated to obtain The first flue gas and the resulting slurry are transported to the first spraying device 4-1 and the second spraying device 4-2 for recycling through the first circulation pump 5-1. When the pH value of the obtained slurry drops below 5, Discharge 40% to 60% of the slurry as the first slurry for subsequent precipitation treatment, and at the same time replenish the same volume of initial slurry from the slurry tank 9 to the first spray tower ₂ ; wherein, the concentration of SO in the flue gas to be treated is 3000mg /m ³ , the concentration of NO is 400mg/m ³ , the flow rate of flue gas to be treated is 2.2m ³ /h, the temperature is 160°C, and the liquid-gas ratio of initial slurry to industrial flue gas is 6L/m ³ ;

In the sedimentation tank 8, the discharged first slurry was subjected to 7h precipitation treatment, and 30% of the supernatant was taken out and the remaining red mud after grinding was added to the circulating slurry tank 12 for mixing to obtain the second slurry with a pH value of 7 ; The remaining supernatant remains on the solid precipitate obtained from the precipitation treatment to form a lower layer of slurry;

The ozone produced by the ozone generator 10 enters the flue gas pipeline between the first spray tower 2 and the second spray tower 11, mixes with the first flue gas for 1.2s, and oxidizes the NO in the first flue gas into NO ₂ and N ₂ O ₅ to obtain the second flue gas; wherein the molar ratio of the ozone produced by the ozone generator 10 to the NO in the first flue gas is 1;

The above-mentioned second slurry enters the second spray tower 11, is sprayed out by the third spray device 7-1 and the fourth spray device 7-2, and performs the second desulfurization and denitrification treatment with the second flue gas to obtain the third slurry and the third flue gas, wherein the liquid-gas ratio of the second slurry to the second flue gas is 5L/m ³ ;

The obtained slurry is transported to the third spraying device 7-1 and the fourth spraying device 7-2 through the third circulation pump 5-3 for recycling until the pH value of the slurry is 4, and the third slurry is discharged, and the magnetic separation method is used The iron in the third slurry is recovered to obtain a red mud slurry, and the red mud slurry is mixed with the lower layer slurry obtained after the first slurry is subjected to precipitation treatment, and the obtained mixed material is used as a raw material for preparing ceramic materials.

The composition of the third flue gas was detected, and the results showed that the concentration of SO ₂ was 84 mg/m ³ , the concentration of NO _x was 137 mg/m ³ , the desulfurization efficiency was 97.2%, and the denitrification efficiency was 65.75%.

Example 3

The above-mentioned Bayer process red mud is ball-milled to 200-300 mesh, and the ground red mud and industrial water are added to the slurry tank 9 according to the mass ratio of solid-to-liquid ratio of 1:25 for mixing to obtain the initial slurry. The initial slurry Enter the first spray tower 2, spray out through the first spray device 4-1 and the second spray device 4-2, and perform the first desulfurization and denitrification treatment with SO ₂ and NO _x in the flue gas to be treated to obtain The first flue gas and the resulting slurry are transported to the first spraying device 4-1 and the second spraying device 4-2 for recycling through the first circulation pump 5-1. When the pH value of the obtained slurry drops below 5, Discharge 30% to 40% of the slurry as the first slurry for subsequent precipitation treatment, and at the same time replenish the same volume of initial slurry from the slurry tank 9 to the first spray tower ₂ ; wherein, the concentration of SO in the flue gas to be treated is 3000mg /m ³ , the concentration of NO is 400mg/m ³ , the flow rate of flue gas to be treated is 2.2m ³ /h, the temperature is 160°C, and the liquid-gas ratio of initial slurry to industrial flue gas is 6L/m ³ ;

In the sedimentation tank 8, the discharged first slurry was subjected to 7h precipitation treatment, and 30% of the supernatant was taken out and the remaining red mud after grinding was added to the circulating slurry tank 12 for mixing to obtain the second slurry with a pH value of 7 ; The remaining supernatant remains on the solid precipitate obtained from the precipitation treatment to form a lower layer of slurry;

The ozone produced by the ozone generator 10 enters the flue gas pipeline between the first spray tower 2 and the second spray tower 11, mixes with the first flue gas for 1.2s, and oxidizes the NO in the first flue gas into NO ₂ and N ₂ O ₅ to obtain the second flue gas; wherein the molar ratio of ozone produced by the ozone generator 10 to NO in the first flue gas is 1.5:1;

The above-mentioned second slurry enters the second spray tower 11, is sprayed out by the third spray device 7-1 and the fourth spray device 7-2, and performs the second desulfurization and denitrification treatment with the second flue gas to obtain the third slurry and the third flue gas, wherein the liquid-gas ratio of the second slurry to the second flue gas is 5L/m ³ ;

The obtained slurry is transported to the third spraying device 7-1 and the fourth spraying device 7-2 through the third circulation pump 5-3 for recycling until the pH value of the slurry is 4, and the third slurry is discharged, and the magnetic separation method is used The iron in the third slurry is recovered to obtain a red mud slurry, and the red mud slurry is mixed with the lower layer slurry obtained after the first slurry is subjected to precipitation treatment, and the obtained mixed material is used as a raw material for preparing ceramic materials.

The composition of the third flue gas was detected, and the results showed that the concentration of SO ₂ was 69 mg/m ³ , the concentration of NO _x was 106 mg/m ³ , the desulfurization efficiency was 97.7%, and the denitrification efficiency was 73.5%.

Example 4

The above-mentioned Bayer process red mud is ball-milled to 200-300 mesh, and the ground red mud and industrial water are added to the slurry tank 9 according to the mass ratio of solid-to-liquid ratio of 1:15 for mixing to obtain the initial slurry. The initial slurry Enter the first spray tower 2, spray out through the first spray device 4-1 and the second spray device 4-2, and perform the first desulfurization and denitrification treatment with SO ₂ and NO _x in the flue gas to be treated to obtain The first flue gas and the resulting slurry are transported to the first spraying device 4-1 and the second spraying device 4-2 for recycling through the first circulation pump 5-1. When the pH value of the obtained slurry drops below 5, Discharge 30% to 40% of the slurry as the first slurry for subsequent precipitation treatment, and at the same time replenish the same volume of initial slurry from the slurry tank 9 to the first spray tower ₂ ; wherein, the concentration of SO in the flue gas to be treated is 3000mg /m ³ , the concentration of NO is 400mg/m ³ , the flow rate of flue gas to be treated is 2.2m ³ /h, the temperature is 160°C, and the liquid-gas ratio of initial slurry to industrial flue gas is 6L/m ³ ;

In the sedimentation tank 8, the discharged first slurry was subjected to 7h precipitation treatment, and 30% of the supernatant was taken out and the remaining red mud after grinding was added to the circulating slurry tank 12 for mixing to obtain the second slurry with a pH value of 7 ; The remaining supernatant remains on the solid precipitate obtained from the precipitation treatment to form a lower layer of slurry;

The ozone produced by the ozone generator 10 enters the flue gas pipeline between the first spray tower 2 and the second spray tower 11, mixes with the first flue gas for 1.2s, and oxidizes the NO in the first flue gas into NO ₂ and N ₂ O ₅ to obtain the second flue gas; wherein the molar ratio of ozone produced by the ozone generator 10 to NO in the first flue gas is 1.8:1;

The above-mentioned second slurry enters the second spray tower 11, is sprayed out by the third spray device 7-1 and the fourth spray device 7-2, and performs the second desulfurization and denitrification treatment with the second flue gas to obtain the third slurry and the third flue gas, wherein the liquid-gas ratio of the second slurry to the second flue gas is 5L/m ³ ;

The obtained slurry is transported to the third spraying device 7-1 and the fourth spraying device 7-2 through the third circulation pump 5-3 for recycling until the pH value of the slurry is 4, and the third slurry is discharged, and the magnetic separation method is used The iron in the third slurry is recovered to obtain a red mud slurry, and the red mud slurry is mixed with the lower layer slurry obtained after the first slurry is subjected to precipitation treatment, and the obtained mixed material is used as a raw material for preparing ceramic materials.

The composition of the third flue gas was detected, and the results showed that the concentration of SO ₂ was 57 mg/m ³ , the concentration of NO _x was 76 mg/m ³ , the desulfurization efficiency was 98.1%, and the denitrification efficiency was 81%.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. a kind of method of flue gas desulfurization and denitrification, which comprises the following steps:

Part red mud is mixed with water, obtains initial slurry；

The initial slurry is mixed with flue gas to be processed, carry out the processing of first time desulphurization denitration, obtain the first slurries and First flue gas；

First slurries are subjected to precipitation process, obtain supernatant；

The supernatant is mixed with remaining red mud, obtains the second slurries；

First flue gas is mixed with ozone, oxidation reaction occurs, obtains the second flue gas；

Second slurries are mixed with second flue gas, second of desulphurization denitration processing are carried out, by gained third cigarette Gas discharge.

2. the method according to claim 1, wherein the mass ratio of the part red mud and water be 1:(10~ 40)。

3. method according to claim 1 or 2, which is characterized in that the granularity of the part red mud and the remaining red mud It independently is 100~300 mesh.

4. the method according to claim 1, wherein the liquid-gas ratio of the initial slurry and flue gas to be processed is 1 ~10L/m³。

5. the method according to claim 1, wherein the time of the precipitation process is 6~10h.

6. the method according to claim 1, wherein the molar ratio of NO and ozone in first flue gas are 1: (1~1.8).

7. method according to claim 1 or 6, which is characterized in that the liquid gas of second slurries and second flue gas Than for 1~6L/m³。

8. the method according to claim 1, wherein first slurries also obtain lower layer after carrying out precipitation process Slurries；Using lower layer's slurries as the raw material for preparing ceramic material；

Third slurries are also obtained after second of desulphurization denitration processing, the iron in the third slurries is recycled using magnetic method, Obtain red mud slurry；Using the red mud slurry as the raw material for preparing ceramic material.

9. a kind of device of flue gas desulfurization and denitrification, which is characterized in that including

Slurry tank (9)；

The first spray column (2) being connected to the discharge port of the slurry tank (9)；

The precipitation tank (8) being connected to the first serum outlet of first spray column (2)；

The recycle slurry liquid bath (12) being connected to the water outlet of the precipitation tank (8)；

The second spray column (11) being connected to the discharge port of the recycle slurry liquid bath (12)；

Second spray column (11) is connected with the first exhanst gas outlet of first spray column (2)；

Ozone generator (10) are provided between first spray column (2) and second spray column (11)；

Flue gas between the ozone outlet and first spray column (2) and the second spray column (11) of the ozone generator (10) Pipeline is connected.

10. device according to claim 9, which is characterized in that further include the first agitating device (3-1) and the second stirring dress It sets (3-2), first agitating device (3-1) is set to the internal bottom of first spray column (2)；The second stirring dress It sets (3-2) and is set to the internal bottom of second spray column (11).