CN107213774B - Flue gas desulfurization and resource utilization method based on smelting tailing slag - Google Patents

Abstract

The invention discloses a flue gas desulfurization and resource utilization method based on smelting tailing slag, which belongs to the field of comprehensive utilization of waste slag and the technical field of industrial waste gas purification. The smelting tailing slag containing iron, zinc, manganese, aluminum and other metals is mixed with water to prepare a desulfurization slurry, and the desulfurization slurry is in countercurrent contact with the flue gas to absorb SO2 in the flue gas and catalyze oxidation into sulfuric _acid , and the sulfuric acid leaches the iron in the slag. , zinc, manganese, aluminum and other elements, and then add oxidizing solution to carry out oxidation, hydrolysis, polymerization reaction, and resource production to obtain polyiron flocculant. The flocculant can be used to treat enterprise wastewater. The invention has simple operation and low cost, not only has better flue gas desulfurization effect, but also can resourcefully produce polyiron-based flocculants and improve the level of high-value resource utilization of slag materials.

Description

A method for flue gas desulfurization and resource utilization based on smelting tailing slag

technical field

The invention relates to a flue gas desulfurization and resource utilization method based on smelting tailing slag, and belongs to the field of comprehensive utilization of waste slag and the technical field of industrial waste gas purification.

technical background

my country is rich in mineral resources. As of 2014, the reserves of copper mines in China were 96.896 million tons. These copper mines are widely distributed in my country, relatively concentrated in Tibet, Yunnan, Jiangxi and other provinces. In recent years, my country's mineral mining has used a large amount, and the annual production of copper-containing slag reaches 9.58 million to 14.37 million tons, and red mud slag is 30 million tons. The components of these slags are complex. The copper-containing slag often contains valuable metals such as Fe, Zn, Ca, Mg, Mn, Al and a small amount of precious metals such as Ag and Au. The Fe content is around 40%, which is much larger than that of iron ore 29.1%. The average industrial grade of Al is mainly in the form of glass body composed of fayalite (Fe ₂ SiO ₄ ), mafic olivine (MgFeSiO ₄ ), magnetite (Fe ₃ O ₄ ), etc. Al is mainly in the form of aluminosilicate Cu is mainly present in the form of matte (CuFeS ₂ ); red mud slag mainly contains Al, Fe, Ca, Si, etc., among which Al in red mud slag is mainly hydrated garnet (3CaO·Al ₂ O ₃ ·SiO _{2 )} . ·4H ₂ O), calcium aluminosilicate (CaO·Al ₂ O ₃ ·2SiO ₂ ) form, Ca in addition to the above two forms, mainly in the form of calcite (CaCO ₃ ), perovskite (CaTiO ₃ ), and at the same time Accompanied by a small amount of impurities, such as Fe ₂ O ₃ , SiO ₂ . These slag cannot be recycled effectively, and improper disposal is potentially harmful to the environment and causes huge waste of resources. At the same time, a large amount of sulfur-containing smelting flue gas is generated during the smelting process, which is often used for industrial acid production, but still contains a large amount of low-concentration sulfur dioxide after the acid production process. The traditional process mainly uses metal oxides containing Na, Ca, Al and other metal oxides, carbon Acid or hydroxide alkaline solution is absorbed, but the cost is high and the resource utilization is difficult, which brings a heavy environmental protection burden to the enterprise.

)、Fe(

)等过渡金属离子添加剂作为催化剂、脱硫剂用于烟气脱硫受到广泛关注，但该工艺需要消耗大量添加剂，运行成本较高，推广困难。中国专利（申请号201210580849.1）利用酸性三价铁溶液作为脱硫剂，吸收烟气中二氧化硫，同时在氧气或臭氧氧化条件下，利用液相催化氧化原理可实现铁的循环，在硫酸根浓度达到较高浓度时最终分离、纯化、结晶得到硫酸铁或氯化铁。中国专利（申请号 201610019014.1）公开了一种用于烟气脱硫的赤泥浆液的配方及其制备方法。其配方赤泥浆液浓度为4%~10%，可用于赤泥周边火力热电厂。中国专利（申请号 201510959956.9）公开了一种利用焙烧冷却后磁铁矿加入至纳米二氧化钛溶液中静置并再次焙烧制备Fenton催化剂方法，该催化剂可有效催化过氧化氢用于烟气脱硫脱硝。但该发明所需Fenton催化剂需在高温条件焙烧，步骤复杂，且需要消耗过氧化氢，因此脱硫成本较高。In recent years, wet flue gas desulfurization and by-product production processes represented by manganese ore, red mud ore, magnesite, zinc dust and other lean slags have been popularized and applied. Such industries have provided new ideas, which can realize the coupling of flue gas desulfurization and resource recovery, and reduce operating costs, but are restricted by the industry due to the distribution of lean ore and other reasons. At the same time, with Fe (

), Fe(

) and other transition metal ion additives are widely concerned as catalysts and desulfurizers for flue gas desulfurization, but this process needs to consume a large amount of additives, has high operating costs, and is difficult to popularize. Chinese patent (Application No. 201210580849.1) uses acidic ferric solution as a desulfurizer to absorb sulfur dioxide in flue gas, and at the same time, under the condition of oxygen or ozone oxidation, the circulation of iron can be realized by using the principle of liquid-phase catalytic oxidation. At high concentration, the final separation, purification and crystallization can obtain ferric sulfate or ferric chloride. The Chinese patent (application number 201610019014.1) discloses a formulation of red mud slurry for flue gas desulfurization and a preparation method thereof. Its formula red mud slurry concentration is 4%~10%, which can be used in thermal power plants around red mud. The Chinese patent (application number 201510959956.9) discloses a method for preparing a Fenton catalyst by adding magnetite to a nano-titania solution after roasting and cooling, and then roasting again. The catalyst can effectively catalyze hydrogen peroxide for flue gas desulfurization and denitration. However, the Fenton catalyst required by the invention needs to be calcined at high temperature, the steps are complicated, and hydrogen peroxide needs to be consumed, so the desulfurization cost is high.

On the other hand, a large amount of acid-containing wastewater is produced in the smelting process, and its composition is complex, containing suspended solids, a variety of high-concentration heavy metals, etc. At the same time, there are other wastewater discharge sources around the smelting industry. The traditional method mainly uses lime neutralization, ferrous sulfate and other reagents to coagulate and precipitate heavy metals, but this process will cause a lot of consumption of chemicals, and problems such as effluent hardness and excessive salinity. Therefore, how to deal with these wastewaters economically and efficiently needs to be solved urgently. The multi-component composite polymer flocculants represented by polyferric sulfate have been continuously developed due to their significant effects on heavily industrially polluted wastewater, and have received high attention. Chinese patent (application number 201410713473.6) discloses a preparation method and application of modified polymeric ferric sulfate for treating industrial wastewater. The modified polymerized ferric sulfate mainly uses ferrous sulfate heptahydrate and sulfuric acid solution to prepare polymerized ferric sulfate under the oxidation of sodium chlorate, and the obtained polymerized ferric sulfate is modified by kaolin and talc, thereby improving the effect of polyiron flocculants on waste paper. The removal rate of COD, SS and chroma in papermaking wastewater can also reduce the amount of flocculant used and the amount of chemical sludge produced, thereby achieving the purpose of saving costs and simplifying the process. Chinese patent (Application No. 201310653910.5) uses ferrous sulfate as flue gas desulfurizer and KClO ₃ /NaClO ₃ as oxidant to realize flue gas desulfurization and synthesize liquid polymerized ferric sulfate in a jet bubbling reactor, but the desulfurization of this invention requires consumption of Large amounts of ferrous sulfate. The Chinese patent (application number 201610045097.7) proposes to use ferrous sulfate and other iron salt components, polyaluminum sulfate and other components as raw materials, and use magnesium chloride, zinc chloride, etc. as coagulant aids to produce a high-efficiency water treatment composite flocculant. The invention effectively exerts the synergistic effect of the aluminum salt and the iron salt, and has excellent flocculation effect, but the cost of the agent is relatively high.

At present, there is no method for producing polyiron-based flocculants based on flue gas desulfurization and resource utilization of smelting tailings.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, the present invention provides a method for producing polyiron-based flocculants based on flue gas desulfurization and resource utilization of smelting tailing slag. The iron, manganese, zinc, aluminum, etc. contained in the tailing slag are Valence metals have good catalytic oxidation ability, and can catalyze the oxidation of low-concentration sulfur dioxide in the flue gas to generate sulfuric acid in the liquid phase. At the same time, the sulfuric acid can further leach metal elements in the slag. Increasingly, by adding oxidant, polyiron-based flocculants can be generated in the desulfurization tower to obtain resource-based by-products, thereby reducing the operating cost of flue gas desulfurization and increasing economic benefits.

The present invention is realized through the following technical solutions: a kind of flue gas desulfurization and resource utilization method based on smelting tailings slag The concrete steps are as follows:

(1) The smelting flue gas is subjected to dedusting and cooling pretreatment to obtain pretreated flue gas A;

(2) Add water to copper tailings and/or red mud waste residue powder to prepare flue gas desulfurization slurry A;

(3) In the reaction vessel, under stirring conditions, the pretreated flue gas A obtained in step (1) and the flue gas desulfurization slurry A obtained in step (2) are formed into a countercurrent contact reaction until the pH value of the desulfurization slurry is uniform at a rate of 1 to 4. Add oxidizing solution to continue the reaction to obtain reaction slurry B and desulfurization gas B, and the concentration of SO ₂ in desulfurization gas B is not higher than 200mg/m ³ when emptying;

(4) filtering the reaction slurry B obtained in step (3) to obtain a filtrate and a filter residue, and concentrating the filtrate to a mass concentration of iron of not less than 11% to obtain a liquid polyiron-based flocculant, and the filter residue is dehydrated;

Further, it also includes spray-drying the liquid polyiron-based flocculant at a temperature of 60-80° C. to obtain a solid polyiron-based flocculant.

In the step (2), the particle size of the smelting tailing slag powder is 200~300 mesh, and the solid-liquid mass ratio of the smelting tailing slag powder and water is 1:(3~10).

The mass percentage concentration of the oxidizing solution is 25-40%, the addition amount of the oxidizing solution is 0.2-10% of the volume of the flue gas desulfurization slurry, and the oxidizing solution is one or any ratio of hydrogen peroxide, sodium chlorate, and sodium hypochlorite. variety.

The temperature at which the filtrate is concentrated in the step (4) is 50-70°C.

The temperature of the pretreatment mixed gas A is lower than 45℃, and the volume concentration of oxygen is 8.0%~19.5%;

In the reaction vessel, the gas residence time is 4~20s;

The smelting flue gas can be a mixed gas of smelting tail gas and environmental collecting flue gas;

_The smelting tail gas is the tail gas containing SO gas released in the non-ferrous metal smelting process;

The environmental flue gas collection refers to the flue gas collected by the large-scale smoke collection system formed by connecting all the fume hoods in the smelting workshop in the smelting plant with pipes;

The main chemical reactions involved in the present invention are as follows:

(1) Principle of pulp flue gas desulfurization

Red mud slurry flue gas desulfurization: Na ₂ O+SO ₂ =Na ₂ SO ₃

4SO ₂ +4Na ₂ O=3Na ₂ SO ₄ +Na ₂ S

4.5SO ₂ +Al ₂ O ₃ =Al ₂ (SO ₄ ) ₃ +1.5S

4CaO+4SO ₂ =3CaSO ₄ +CaS

2Fe ²⁺ +SO ₂ +O ₂ =2Fe ³⁺ +SO ₄ ^2-

2Fe ³⁺ +SO ₂ +2H ₂ O=2Fe ³⁺ +SO ₄ ^2- +4H ⁺

Copper pulp flue gas desulfurization:

H₂SO₃

H⁺+HSO₃ ^- SO ₂ +H ₂ O

H ₂ SO ₃

H ⁺ +HSO ₃ ^-

2Fe ²⁺ +SO ₂ +O ₂ =2Fe ³⁺ +SO ₄ ^2-

2Fe ³⁺ +SO ₂ +2H ₂ O=2Fe ³⁺ +SO ₄ ^2- +4H ⁺

Fe ₂ SiO ₄ +2SO ₂ +O ₂ = 2FeSO ₄ + SiO ₂ ↓

FeSO ₄ +SO ₂ +O ₂ =Fe ₂ (SO ₄ ) ₃

Fe ₂ (SO ₄ ) ₃ +SO ₂ +2H ₂ O=2FeSO ₄ +2H ₂ SO ₄

The overall reaction can be summarized as

H₂SO₄ 2SO ₂ +2H ₂ O+O ₂

H ₂ SO ₄

(2) Production principle of polyiron flocculants

Oxidation: 2FeSO ₄ +H ₂ O ₂ +H ₂ SO ₄ =Fe ₂ (SO ₄ ) ₃ +2H ₂ O

Hydrolysis: Fe ₂ (SO ₄ ) ₃ +nH ₂ O=Fe ₂ (OH) _n (SO ₄ ) _3-n/2 +n/2H ₂ SO ₄

Polymerization: mFe ₂ (OH) _n (SO ₄ ) _3-n/2 =[Fe ₂ (OH) _n (SO ₄ ) _3-n/2 ] _m

The beneficial effects of the present invention are:

(1) In the present invention, smelting tailing slag is used for smelting flue gas desulfurization, and its sulfur dioxide removal rate is greater than 90%, realizing waste treatment with waste;

(2) The present invention utilizes the catalytic oxidation ability of valuable metals such as iron, manganese, zinc, and copper in the tailings slag, catalyzes oxidation of low-concentration sulfur dioxide in the flue gas in the liquid phase to generate sulfuric acid, and the sulfuric acid leaches the metal elements in the slag, and the reaction proceeds as the reaction proceeds. , the concentration of iron, manganese, aluminum and other metals in the absorption liquid continues to increase. By adding oxidant, a resource-based by-product, i.e. polyiron flocculant, is generated in the desulfurization tower, thereby reducing the operating cost of flue gas desulfurization and increasing economic benefits;

(3) The water obtained by the dehydration treatment of the filter residue of the present invention can be used as industrial water again, reducing the treatment load of flue gas desulfurization sewage in the enterprise;

(4) The polyiron-based flocculant obtained by the resource utilization of the present invention can be applied to wastewater treatment.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

Example 1: In this example, 10000 mg/ ^m3 sulfur dioxide cylinder gas with a purity of 99.5% nitrogen cylinder gas is used, and the air pump is pumped through a mass flow meter to accurately mix and prepare mixed gas A to simulate smelting flue gas. The gas flow rate is 1.2L/min, the mass fraction of oxygen is 19.5%, and the concentration of SO ₂ is 1500 mg/m ³ ;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) Add water to copper tailings waste residue powder to prepare flue gas desulfurization slurry A, wherein the particle size of smelting tailings slag powder is 200 mesh, and the solid-liquid mass ratio of smelting tailings slag powder and water is 1:4;

(2) The flue gas desulfurization slurry A obtained in step (1) is transported to the spray device at the top of the slurry desulfurization bubbling reactor through a slurry pump;

(3) Pass the mixed gas A into the bottom of the pulp desulfurization bubbling reactor, and under stirring conditions, make the mixed gas A and the flue gas desulfurization slurry obtained in step (2) form a countercurrent contact reaction in the pulp desulfurization bubbling reactor to When the pH value of the desulfurization slurry is 1, the oxidizing solution is added at a constant speed to continue the reaction to obtain the reaction slurry B and the desulfurization gas B. When the concentration of SO2 in the desulfurization gas B is lower _than 150mg/ ^m3 , it is directly evacuated, and the oxidizing solution is the mass The fraction of hydrogen peroxide solution is 30%, and the amount of oxidizing solution (hydrogen peroxide solution) is 4% of the volume of the flue gas desulfurization slurry;

(4) When the concentration of SO ₂ in the desulfurized gas B is 150 mg/m ³ , filter the reaction slurry B obtained in step (3) to obtain a filtrate and a filter residue, and at a temperature of 60 ° C, the filtrate is concentrated by a rotary evaporator to The mass concentration of iron is 12.8% to obtain a liquid polyiron flocculant, and the filter residue is dehydrated;

In this embodiment, the HC-6 type sulfur and phosphorus analyzer is used to detect the concentration of sulfur dioxide at the inlet and outlet, and the temperature of the desulfurization slurry and the stirring speed are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this example, the concentration of SO ₂ in the desulfurized gas B is 150 mg/m ³ , the desulfurization efficiency of the mixed gas A is 90%, the total iron mass fraction in the liquid polyiron-based flocculant is 12.8%, and the reducing substances (as Fe ^{2 +} meter) The mass fraction is 0.12%, and the basicity is 14.2%, which meets the requirements of the national standard GB 14591-2006.

Embodiment 2: The smelting flue gas in this embodiment is the mixed gas of flue gas generated in the process of copper smelting and acid production and environmental flue gas collected by the environment. The flue gas volume of the mixed gas is 100000 Nm ³ /h, and the SO ₂ concentration in the flue gas 1200 mg/Nm ³ , O ₂ volume concentration 19.5%;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) The smelting flue gas is subjected to dust removal and cooling pretreatment to obtain pretreated flue gas A, wherein the temperature of pretreated flue gas A is 25 °C, and the volume concentration of O ₂ is 19.5%;

(2) Add water to copper tailings waste residue powder to prepare flue gas desulfurization slurry A, wherein the particle size of smelting tailings slag powder is 200 mesh, and the solid-liquid mass ratio of smelting tailings slag powder and water is 1:5; The gas desulfurization slurry A is transported to the spray device at the top of the desulfurization tower through the slurry pump;

(3) The pretreated flue gas A obtained in step (1) is pressurized to 0.20~0.25 Kpa by a blower, and then passed into the bottom end of the desulfurization tower. Under stirring conditions, the mixed gas A and the flue gas obtained in step (2) are mixed The desulfurization slurry forms a countercurrent contact reaction in the desulfurization tower until the pH value of the desulfurization slurry is 1. When the pH value of the desulfurization slurry is 1, the oxidizing solution is added at a constant speed to continue the reaction to obtain the reaction slurry B and the desulfurization gas B. The concentration of SO ₂ in the desulfurization gas B is lower than 100mg/m ³ The oxidizing solution is a hydrogen peroxide solution with a mass fraction of 35%, and the addition amount of the oxidizing solution (hydrogen peroxide solution) is 1.5% of the volume of the flue gas desulfurization slurry, so that some Fe ^{2 +} is oxidized to Fe ³⁺ , which promotes the oxidation of sulfur dioxide;

(4) When the concentration of SO ₂ in the desulfurized gas B is 100 mg/m ³ , the reaction slurry B obtained in step (3) is filtered to obtain a filtrate and a filter residue (the filter residue is copper tailings residue), and the temperature is 70 ℃. , the filtrate is concentrated by a rotary evaporator to a mass concentration of iron of 11.20% to obtain a liquid polyiron-based flocculant, the filter residue is dehydrated, stacked and recycled as a building material or further recovered by hot alkali dissolution to recover silicon in the residue;

(5) Under the condition of temperature of 70℃, spray-drying the liquid polyiron-based flocculant to obtain a solid polyiron-based flocculant;

In this example, the concentration of sulfur dioxide at the inlet and outlet is detected by the HC-6 type sulfur and phosphorus analyzer, and the temperature and stirring speed of the desulfurization slurry are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this embodiment, the concentration of SO ₂ in the desulfurized gas B is 100 mg/m ³ , the desulfurization efficiency of the mixed gas A is 91.6%, the total iron mass fraction in the liquid polyiron-based flocculant is 11.20%, and the reducing substances (as Fe ^{2 +} meter) The mass fraction is 0.042%, and the basicity is 12.45%, which meets the requirements of the national standard GB 14591-2006.

Embodiment 3: The smelting flue gas of this embodiment is the mixed gas of flue gas generated in the process of copper smelting and acid production and environmental flue gas collection flue gas, the flue gas volume of the mixed gas is 200000Nm ³ /h, and the SO ₂ concentration in the flue gas is 1400 mg/Nm ³ , O ₂ volume concentration 19.0%;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) The smelting flue gas is subjected to dust removal and cooling pretreatment to obtain pretreated flue gas A, wherein the temperature of pretreated flue gas A is 30 °C, and the volume concentration of O ₂ is 19.0%;

(2) Add water to copper tailings waste residue powder to prepare flue gas desulfurization slurry A, wherein the particle size of smelting tailings slag powder is 200 mesh, and the solid-liquid mass ratio of smelting tailings slag powder and water is 1:5; The gas desulfurization slurry A is transported to the spray device at the top of the desulfurization tower through the slurry pump;

(3) The pretreated flue gas A obtained in step (1) is pressurized to 0.20~0.30Kpa by a blower, and then passed into the bottom end of the desulfurization tower. Under stirring conditions, the mixed gas A and the flue gas obtained in step (2) are mixed The desulfurization slurry forms a countercurrent contact reaction in the desulfurization tower until the pH value of the desulfurization slurry is 1.5. When the pH value of the desulfurization slurry is 1.5, the oxidizing solution is added at a constant speed to continue the reaction to obtain the reaction slurry B and the desulfurization gas B. The concentration of SO ₂ in the desulfurization gas B is lower than 100mg/m ³ The oxidizing solution is a hydrogen peroxide solution with a mass fraction of 40%, and the addition amount of the oxidizing solution (hydrogen peroxide solution) is 2.5% of the volume of the flue gas desulfurization slurry, so that some Fe ^{2 +} is oxidized to Fe ³⁺ , which promotes the oxidation of sulfur dioxide;

(4) When the concentration of SO ₂ in the desulfurized gas B is 100 mg/m ³ , the reaction slurry B obtained in step (3) is filtered to obtain a filtrate and a filter residue (the filter residue is copper tailings residue), and the temperature is 70 ℃. , the filtrate is concentrated to a mass concentration of 11.02% of iron by a rotary evaporator to obtain a liquid polyiron-based flocculant, the filter residue is dehydrated, stacked and recycled as a building material or further recovered by hot alkali dissolution to recover silicon in the residue;

(5) Under the condition of temperature of 70℃, spray-drying the liquid polyiron-based flocculant to obtain a solid polyiron-based flocculant;

In this example, the concentration of sulfur dioxide at the inlet and outlet is detected by the HC-6 type sulfur and phosphorus analyzer, and the temperature and stirring speed of the desulfurization slurry are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this embodiment, the concentration of SO ₂ in the desulfurized gas B is 100 mg/m ³ , the desulfurization efficiency of the mixed gas A is 91.6%, the total iron mass fraction in the liquid polyiron-based flocculant is 11.02%, and the reducing substances (as Fe ^{2 +} meter) The mass fraction is 0.01%, and the basicity is 14.56%, which meets the requirements of the national standard GB 14591-2006.

Embodiment 4: The smelting flue gas in this embodiment is the mixed gas of the alumina smelting supporting thermal power plant and the environmental flue gas collection, the flue gas volume of the mixed gas is 100000Nm ³ /h, and the SO ₂ concentration in the flue gas is 2000 mg/Nm ³ , O ₂ volume concentration 8.0%;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) The smelting flue gas is subjected to dust removal and cooling pretreatment to obtain pretreated flue gas A, wherein the temperature of pretreated flue gas A is 44.8 °C, and the volume concentration of O ₂ is 8.0%;

(2) Add water to red mud waste residue powder to prepare flue gas desulfurization slurry A, wherein the particle size of smelting waste residue powder is 300 mesh, and the solid-liquid mass ratio of smelting tailing slag powder and water is 1:3; The slurry A is transported to the spray device at the top of the desulfurization tower through the slurry pump;

(3) The pretreated flue gas A obtained in step (1) is pressurized to 0.20~0.30Kpa by a blower, and then passed into the bottom end of the desulfurization tower. Under stirring conditions, the mixed gas A and the flue gas obtained in step (2) are mixed The desulfurization slurry forms a countercurrent contact reaction in the desulfurization tower until the pH value of the desulfurization slurry is 4. When the pH value of the desulfurization slurry is 4, the oxidizing solution is added at a constant speed to continue the reaction to obtain the reaction slurry B and the desulfurized gas B. The concentration of SO ₂ in the desulfurized gas B is lower than 200mg/m ³ The oxidizing solution is a sodium chlorate solution with a mass fraction of 40%, and the addition amount of the oxidizing solution (sodium chlorate solution) is 10% of the volume of the flue gas desulfurization slurry, so that some Fe ^{2 +} is oxidized to Fe ³⁺ , which promotes the oxidation of sulfur dioxide;

(4) When the concentration of SO ₂ in the desulfurized gas B is 200 mg/m ³ , filter the reaction slurry B obtained in step (3) to obtain a filtrate and a filter residue (the filter residue is red mud residue). The filtrate is concentrated to a mass concentration of iron of 11.01% by a rotary evaporator to obtain a liquid polyiron-based flocculant, and the filter residue is dehydrated;

(5) Under the condition of temperature of 60℃, spray-drying the liquid polyiron-based flocculant to obtain a solid polyiron-based flocculant;

In this example, the concentration of sulfur dioxide at the inlet and outlet is detected by the HC-6 type sulfur and phosphorus analyzer, and the temperature and stirring speed of the desulfurization slurry are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this embodiment, the concentration of SO ₂ in the desulfurized gas B is 200 mg/m ³ , the desulfurization efficiency of the mixed gas A is 90%, the total iron mass fraction in the liquid polyiron-based flocculant is 11.01%, and the reducing substances (as Fe ^{2 +} meter) the mass fraction is 0.01%, and the basicity is 14.2%, which meets the requirements of the national standard GB 14591-2006.

Example ⁵ : _The smelting flue gas in this example is the mixed gas ^of the alumina smelting supporting thermal power plant and the environmental flue gas collection. O ₂ volume concentration 16.0%;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) The smelting flue gas is subjected to dust removal and cooling pretreatment to obtain pretreated flue gas A, wherein the temperature of pretreated flue gas A is 35 °C, and the volume concentration of O ₂ is 16.0%;

(2) Add water to the waste residue powder of red mud to prepare flue gas desulfurization slurry A, wherein the particle size of smelting tailing slag powder is 220 mesh, and the solid-liquid mass ratio of smelting tailing slag powder and water is 1:10; The gas desulfurization slurry A is transported to the spray device at the top of the desulfurization tower through the slurry pump;

(3) The pretreated flue gas A obtained in step (1) is pressurized to 0.20~0.30Kpa by a blower, and then passed into the bottom end of the desulfurization tower. Under stirring conditions, the mixed gas A and the flue gas obtained in step (2) are mixed The desulfurization slurry forms a countercurrent contact reaction in the desulfurization tower. When the pH value of the desulfurization slurry is 2.5, the oxidizing solution is added at a constant speed to continue the reaction to obtain the reaction slurry B and the desulfurization gas B. The concentration of SO ₂ in the desulfurization gas B is lower than 120mg/m ³ The oxidizing solution is 28% hydrogen peroxide solution and 30% sodium hypochlorite solution according to the volume ratio of hydrogen peroxide solution and sodium hypochlorite solution is 2:1. Mixed oxidizing solution, the added amount of mixed oxidizing solution is 5.6% of the volume of flue gas desulfurization slurry, so that part of Fe ²⁺ in the slurry is oxidized to Fe ³⁺ , and the oxidation of sulfur dioxide is promoted;

(4) When the concentration of SO ₂ in the desulfurized gas B is 120 mg/m ³ , filter the reaction slurry B obtained in step (3) to obtain a filtrate and a filter residue (the filter residue is red mud residue). The filtrate is concentrated to an iron mass concentration of 11.05% by a rotary evaporator to obtain a liquid poly-iron-based flocculant, the filter residue is dehydrated, and stacked for recycling as a building material or further to recover silicon in the residue by hot alkali dissolution;

(5) Under the condition of temperature of 80℃, spray-drying the liquid polyiron-based flocculant to obtain a solid polyiron-based flocculant;

In this example, the concentration of sulfur dioxide at the inlet and outlet is detected by the HC-6 type sulfur and phosphorus analyzer, and the temperature and stirring speed of the desulfurization slurry are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this example, the concentration of SO ₂ in the desulfurized gas B is 120 mg/m ³ , the desulfurization efficiency of the mixed gas A is 93.3%, the mass fraction of total iron in the liquid polyiron-based flocculant is 11.05%, and the reducing substances (as Fe ^{2 +} meter) The mass fraction is 0.04%, and the basicity is 15.8%, which meets the requirements of the national standard GB 14591-2006.

Example 6: The smelting flue gas in this example is a mixed gas of copper smelting acid production flue gas and environmental flue gas collection flue gas, the flue gas volume of the mixed gas is 120,000Nm ³ /h, and the SO ₂ concentration in the flue gas is 1000mg/Nm ³ , O ₂ volume concentration 12.0%;

A flue gas desulfurization and resource utilization method based on smelting tailings slag, the specific steps are as follows:

(1) The smelting flue gas is subjected to dust removal and cooling pretreatment to obtain pretreated flue gas A, wherein the temperature of pretreated flue gas A is 35 °C, and the volume concentration of O ₂ is 12.0%;

(2) Add water to copper tailings and red mud waste residue powder to prepare flue gas desulfurization slurry A, in which the particle size of smelting tailing slag powder is 260 mesh, and the solid-liquid mass ratio of smelting tailing slag powder and water is 1:8 ; The flue gas desulfurization slurry A is transported to the spray device at the top of the desulfurization tower through the slurry pump;

(3) The pretreated flue gas A obtained in step (1) is pressurized to 0.20~0.30Kpa by a blower, and then passed into the bottom end of the desulfurization tower. Under stirring conditions, the mixed gas A and the flue gas obtained in step (2) are mixed The desulfurization slurry forms a countercurrent contact reaction in the desulfurization tower until the pH value of the desulfurization slurry is 2.0. When the pH value of the desulfurization slurry is 2.0, the oxidizing solution is added at a constant speed to continue the reaction to obtain a reaction slurry B and a desulfurization gas B. The concentration of SO ₂ in the desulfurization gas B is lower than 90mg/m ³ The oxidizing solution is sodium hypochlorite with a mass fraction of 35%, and the amount of oxidizing solution (sodium hypochlorite solution) added is 3.8% of the volume of the flue gas desulfurization slurry, so that part of the Fe ²⁺ in the slurry is oxidized to Fe ³⁺ , to promote the oxidation of sulfur dioxide;

(4) When the concentration of SO ₂ in the desulfurized gas B is 90 mg/m ³ , filter the reaction slurry B obtained in step (3) to obtain a filtrate and a filter residue (the filter residue is copper tailings residue), and the temperature is 65 ℃. , the filtrate is concentrated to a mass concentration of 11.02% of iron by a rotary evaporator to obtain a liquid polyiron-based flocculant, the filter residue is dehydrated, stacked and recycled as a building material or further recovered by hot alkali dissolution to recover silicon in the residue;

(5) Under the condition of temperature of 70℃, spray-drying the liquid polyiron-based flocculant to obtain a solid polyiron-based flocculant;

In this example, the concentration of sulfur dioxide at the inlet and outlet is detected by the HC-6 type sulfur and phosphorus analyzer, and the temperature and stirring speed of the desulfurization slurry are controlled by a constant temperature magnetic stirrer; Indicators such as reducing substances, salinity, etc.;

In this example, the concentration of SO ₂ in the desulfurized gas B is 90 mg/m ³ , the desulfurization efficiency of the mixed gas A is 91%, the total iron mass fraction in the liquid polyiron-based flocculant is 11.01%, and the reducing substances (as Fe ^{2 +} meter) The mass fraction is 0.067%, and the basicity is 14.28%, which meets the requirements of the national standard GB 14591-2006.

Claims (5)

1. a flue gas desulfurization and resource utilization method based on smelting tailing slag, is characterized in that, concrete steps are: (1) Pretreatment of smelting flue gas through dust removal and cooling to obtain pretreated flue gas A; the temperature of pretreated mixed gas A is lower than 45°C, and the volume concentration of oxygen is 8.0% to 19.5%; (2) adding water to copper tailings and/or red mud waste residue powder to prepare flue gas desulfurization slurry A; (3) in the reaction vessel, under stirring conditions, the pretreated flue gas A obtained in step (1) and the flue gas desulfurization slurry A obtained in step (2) are formed into a countercurrent contact reaction to a uniform speed when the pH value of the desulfurization slurry is 1 to 4 Add oxidizing solution to continue the reaction to obtain reaction slurry B and desulfurization gas B, and the concentration of SO ₂ in desulfurization gas B is not higher than 200mg/m ³ when emptying; (4) Filtration of the reaction slurry B obtained in step (3) to obtain filtrate and filter residue, the filtrate is concentrated to a mass concentration of iron of not less than 11% to obtain a liquid polyiron-based flocculant, and the filter residue is dehydrated. 2. The flue gas desulfurization and resource utilization method based on smelting tailings slag according to claim 1, characterized in that: further comprising, under the condition that the temperature is 60-80 ℃, spray-drying the liquid poly-iron-based flocculant to obtain solid poly- Iron based flocculants. 3. The flue gas desulfurization and resource utilization method based on smelting tailing slag according to claim 1 or 2, it is characterized in that: in step (2), the particle size of smelting tailing slag powder is 200～300 meshes, and the smelting tailing slag powder is 200～300 meshes. The solid-liquid mass ratio with water is 1:(3～10). 4. The flue gas desulfurization and resource utilization method based on smelting tailing slag according to claim 1 or 2, characterized in that: the mass percentage concentration of the oxidizing solution is 25～40%, and the addition of the oxidizing solution is the flue gas 0.2-10% of the volume of the desulfurization slurry, and the oxidizing solution is one or any ratio of hydrogen peroxide, sodium chlorate, and sodium hypochlorite. 5. The flue gas desulfurization and resource utilization method based on smelting tailings slag according to claim 1 or 2, characterized in that: in step (4), the temperature at which the filtrate is concentrated is 50-70°C.