CN113521979A

CN113521979A - Method for trapping mercury from sulfur-containing mercury-containing flue gas through chlorine selenium mercury deposition

Info

Publication number: CN113521979A
Application number: CN202110923109.2A
Authority: CN
Inventors: 徐浩淼; 晏乃强; 瞿赞; 黄文君; 洪钦源; 范宇睿
Original assignee: Shanghai Jiao Tong University
Current assignee: Henan Yuguang Gold and Lead Co Ltd; Shanghai Jiao Tong University
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2021-10-22
Anticipated expiration: 2041-08-12
Also published as: CN113521979B

Abstract

The present invention relates to a method for capturing mercury from sulfur-containing and mercury-containing flue gas by deposition of chloroselenium and mercury, comprising the following steps: (1) after dust removal and waste heat recovery from non-ferrous smelting raw flue gas, a certain amount of flue gas is sprayed into it. The water mist reduces the temperature to around the dew point, so that the selenium dioxide in the flue gas is reduced to active elemental selenium that can react quickly with mercury in the flue gas under the combined action of sulfur dioxide and water vapor, and HCl in the flue gas. Under the action of the chloroselenide mercury compound, which is easy to deposit; (2) the flue gas is then contacted with the matrix material, and through its surface induction effect, the formation and deposition of chloroselenomercuric mercury is accelerated, so that the mercury in the flue gas is trapped to the substrate surface. Compared with the prior art, the method of the present invention can realize the efficient capture and recovery of mercury in the semi-dry state of the flue gas, and avoid excessive entry of the mercury into the downstream scrubbing acid or acid-making system, thereby resulting in a decrease in the recovery rate and cross-media transfer, etc. Secondary pollution problem.

Description

Method for trapping mercury from sulfur-containing mercury-containing flue gas through chlorine selenium mercury deposition

Technical Field

The invention belongs to the field of environmental protection, mainly aims at removing and recovering industrial waste gas mercury, and relates to a method for trapping mercury from sulfur-containing mercury-containing flue gas through chlorine selenium mercury deposition and a matrix material.

Background

Mercury has characteristics of long-distance migration, high biological enrichment, high toxicity and the like, and is one of the pollutants of major global concern. The "water guarantee convention on mercury" that has been formally put into effect aims at cutting off the emission source of mercury globally, restricting the regional circulation of products containing mercury, and prescribing the control of atmospheric mercury emissions for key industries such as coal-fired power plants, industrial boilers, non-ferrous metal metallurgy, cement production, and the like. As the largest mercury discharge country, coal-fired power generation and non-ferrous metal smelting are the most main mercury discharge sources in China, and the mercury discharge reduction pressure is huge. With the increasing concern on air pollution in recent years, the ultra-low emission standard with the worst history is formed in the coal-fired power generation industry, and mercury is synchronously and efficiently removed in the ultra-low emission process while the control technology of sulfur oxides, nitrogen oxides and particulate matters is upgraded and modified. However, the emission characteristics of mercury in the nonferrous smelting industry are completely different from those of the coal-fired power generation industry, and ores with metal sulfides as main components release a large amount of SO in the high-temperature roasting process₂And pollutants such as particulate matters and heavy metals can be partially treated and easily dissolved pollutants (SO) can be removed by using pollution control equipment such as dust collection equipment and wet washing equipment in the process of downstream migration of flue gas₃Selenium, chlorine, etc.) and purified to contain high concentration of SO₂(in general)>4%) is used for preparing sulfuric acid by a two-conversion and two-absorption process to realize SO in the flue gas₂And the efficient purification of a large amount of conventional pollutants such as particulate matters and the utilization of sulfur resources. However, the mercury in the flue gas is mainly zero-valent mercury (Hg)⁰) Due to its stabilityThe high-solubility sulfuric acid is high in solubility and low in solubility, and is easy to enter an acid making process along with flue gas, and the flue gas at the upstream needs to be intercepted and trapped, so that the waste acid treatment difficulty is reduced, and the quality of a sulfuric acid product is improved.

Patent ZL201310277066.0 discloses a method for recovering gaseous zero-valent mercury and sulfur dioxide from non-ferrous metal smelting flue gas, which comprises the steps of preparing a composite absorption liquid by taking mercury sulfate, ferric sulfate and sulfuric acid as main components, efficiently absorbing the zero-valent mercury in the flue gas by using an absorption tower, converting the zero-valent mercury into mercury sulfite, and generating the sulfuric acid by using the reaction of the ferric sulfate and the sulfur dioxide. And decomposing the generated mercury sulfite into elemental mercury and mercury sulfate through a recovery device. Compared with the prior art, the invention can improve the absorption efficiency of the zero-valent mercury in the flue gas, reduce the usage amount of the absorbent and realize the recovery of the zero-valent mercury. Meanwhile, the sulfuric acid can be recovered through the absorption of the sulfur dioxide, and the Hg in the sulfur dioxide can be reduced²⁺The reduction effect of the method improves the total recovery rate of zero-valent mercury, so the method is very suitable for controlling the mercury emission of flue gas with higher concentration of sulfur dioxide. However, the method needs a separate mercury removal device and a corresponding solution, so that the cost is high, the mercury removal efficiency is gradually lost along with the reduction of the solution concentration, and the method is difficult to apply to complex flue gas.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for trapping mercury from sulfur-containing and mercury-containing flue gas by chlorine selenium mercury deposition.

The purpose of the invention can be realized by the following technical scheme: a method for capturing mercury from sulfur-containing mercury-containing flue gases by chlorine selenium mercury deposition, comprising the steps of:

(1) after dedusting and waste heat recovery, spraying a certain amount of water mist into the non-ferrous smelting raw flue gas, reducing the temperature of the non-ferrous smelting raw flue gas to be near a dew point, reducing selenium dioxide in the flue gas into active elemental selenium capable of rapidly reacting with mercury in the flue gas under the combined action of sulfur dioxide and water vapor, and generating a chlorine selenium mercury compound easy to deposit under the action of HCl in the flue gas;

(2) then the flue gas is contacted with the substrate material, and the generation and deposition of the chlorine selenium mercury are accelerated through the surface induction effect, so that the mercury in the flue gas is trapped on the surface of the substrate.

Further, the non-ferrous smelting raw flue gas contains mercury, oxysulfide, selenium dioxide and hydrogen chloride;

the temperature of the flue gas after upstream flue gas dust removal and waste heat recovery is reduced to below 250 ℃, mercury in the flue gas mainly exists in a zero-valent mercury form, and the concentration range of the mercury is 0.1-50mg/m³，SO₂The concentration is 0.2% -5%, SeO₂The concentration is 100-2000mg/m³The HCl concentration is 20-500mg/m³。

Further, spraying water mist into the flue gas in the step (1), and uniformly spraying water into the flue gas by using a high-efficiency atomizing nozzle to reduce the temperature of the flue gas to a degree that the temperature is 5-10 ℃ higher than the dew point temperature of the flue gas;

the water used for spraying the water mist is process water or acidic waste water without particles, and the water spraying amount is used for reducing the temperature of the flue gas to be near the dew point.

Further, in the step (1), when the temperature of the flue gas is reduced to be near the dew point, the selenium dioxide in the flue gas is rapidly reduced into active elemental selenium by sulfur dioxide, and the reduction rate of the selenium dioxide reaches more than 10%; through the combined action of HCl in the flue gas, gas-phase zero-valent mercury is converted into chlorine selenium mercury, and the gas-phase conversion rate of mercury can reach 5-20%.

Further, the matrix material in the step (2) is a metal oxide or a porous material;

the metal oxide comprises aluminum oxide, zinc oxide, titanium dioxide or iron oxide;

the porous material is active carbon or silicon dioxide.

Further, the contact mode of the smoke and the matrix material in the step (2) is as follows:

the matrix material is directly sprayed into the smoke in the form of 100-300 mesh powder, and the concentration of the matrix material sprayed into the smoke is 5-50g/m³And the downstream is provided with a bag type dust collector for collection.

Or preparing the matrix material into spherical or columnar particles with diameter of 2-10mm, and making into fixed bed or moving bedThe space velocity (i.e. the volume of gas that can be treated in 1 hour per cubic meter of adsorbent) used is 2000-^-1。

Further, the step (2) promotes the further conversion of the mercury in the flue gas to the mercury diselenide chloride through the surface induction effect of the matrix material, and the total conversion efficiency is more than 80%.

When the selenium dioxide or HCl in the flue gas is insufficient, the surface of the substrate material is modified, the content of chlorine or selenium on the surface of the substrate material is increased, and the phenomena of escape and secondary pollution caused by directly spraying the substances into the flue gas are avoided.

Furthermore, when the concentration of selenium dioxide in the smoke is lower than 200mg/m³When in use, the matrix material is subjected to impregnation modification by using a 5-20% sodium selenite solution, so that the material is loaded with 1-5% of selenium, and the selenium is dried in the air and can be used;

when the HCl concentration in the flue gas per se is lower than 50mg/m³When in use, the matrix material is impregnated and modified by 5 to 10 percent sodium chloride solution, so that the material is loaded with 0.5 to 2 percent chlorine by mass of elemental chlorine and can be used after being dried.

Further, when the chlorine selenium mercury on the surface of the substrate material is accumulated to a certain amount (when the deposition amount of the chlorine selenium mercury on the substrate material reaches more than 50g/kg, the part of the substrate material needs to be taken out and regenerated), the part of the substrate material is taken out from the flue gas, the regenerated mercury and selenium are respectively collected and recovered by a condensation method by a heating regeneration method, and the regenerated substrate material can be recycled after being modified by surface conditioning.

Furthermore, the substrate material deposited with the chlorine selenium mercury is treated by a heating regeneration method, the substrate is heated to 400 ℃ for 300-.

Compared with the prior art, the invention has the following advantages:

1) the invention provides a method for reducing selenium dioxide into active elemental selenium with high-efficiency mercury trapping capacity by properly spraying and humidifying non-ferrous smelting flue gas after upstream dust removal, and the selenium dioxide is promoted to reduce selenium dioxide into active elemental selenium under the combined action of chlorine in the flue gas, and the chlorine selenium mercury is formed and deposited on the surface of a substrate which can be contacted therewith, so that the high-efficiency trapping and recovery of mercury can be realized in a semi-dry state of the flue gas, and the problems of secondary pollution such as recovery rate reduction, cross-medium transfer and the like caused by excessive entry into a downstream washing waste acid or acid making system are avoided.

2) The mercury capturing method can realize the high-efficiency capturing of mercury in a semi-dry state of flue gas, and avoid the problem of secondary pollution such as recovery rate reduction, cross-medium transfer and the like caused by excessive entry of mercury into a downstream washing waste acid or acid making system;

3) the matrix material conditioning method is simple, has low energy consumption and can be used for experimental large-scale production;

4) after the matrix material is used, selenium and mercury resources can be recovered through heating regeneration, and the matrix material can be recycled.

Drawings

FIG. 1 is a process flow diagram of a method of the present invention for capturing mercury from sulfur-containing mercury-containing flue gases by mercury diselenide deposition.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, a method and a matrix material for trapping mercury from sulfur-containing mercury-containing flue gas by chlorine selenium mercury deposition mainly comprise the following steps:

the first step is as follows: the method comprises the following steps of spraying a certain amount of water mist I102 into non-ferrous smelting raw flue gas I101 after dust removal and waste heat recovery by a dust remover 1, and reducing the temperature of the non-ferrous smelting raw flue gas to be near a dew point (the temperature of the flue gas can be reduced to be below 250 ℃, or the temperature of the flue gas is reduced to be higher than the dew point by 5-10 ℃), so that selenium dioxide in the flue gas is reduced to active elemental selenium capable of rapidly reacting with mercury in the flue gas under the combined action of sulfur dioxide and water vapor, and the reduction rate of the selenium dioxide can reach more than 10%; under the action of HCl in the flue gas, the active elemental selenium generates a chlorine selenium mercury compound which is easy to deposit; gas-phase zero-valent mercury is converted into chlorine selenium mercury, and the conversion rate of mercury can reach 5-20%;

the non-ferrous smelting raw flue gas I101 is mercury-containing and sulfur oxide waste gas generated in the non-ferrous smelting industry, and also contains a certain amount of selenium dioxide and hydrogen chloride. The temperature of the flue gas is reduced to be near the dew point through upstream flue gas dust removal and waste heat recovery. The mercury in the flue gas exists mainly in the form of zero-valent mercury, and the concentration range of the mercury is 0.1-50mg/m³；SO₂The concentration is 0.2% -5%. SeO₂The concentration is 100-2000mg/m³The HCl concentration is 20-500mg/m³。

The water mist I102 is uniformly sprayed into the flue gas through the high-efficiency atomizing nozzle, so that the temperature of the flue gas is reduced to the degree that the temperature is 5-10 ℃ higher than the dew point temperature of the flue gas. The water used may be process water or acidic waste water free of particulate matter.

The second step is that: the substrate material 2 which is beneficial to deposition of elemental selenium or mercury selenide is used in the flue gas at the downstream, and the generation and deposition of chlorine selenium mercury are accelerated through the surface induction effect, so that mercury in the flue gas is trapped on the surface of the substrate;

the matrix material is metal oxides such as aluminum oxide, zinc oxide, titanium dioxide, iron oxide and the like, or porous materials such as active carbon, silicon dioxide and the like. Can be directly sprayed into the flue gas in 100-300 mesh powder or prepared into spherical or columnar particles with the diameter of 2-10mm, and the particles are contacted with the flue gas in a fixed bed or moving bed mode;

the matrix material is powder or particles. When the substrate is powdery, the concentration of the substrate sprayed into the flue gas is 5-50g/m³The downstream is provided with a bag type dust collector for collection; when the substrate is particles, the flue gas is treated by adopting a fixed bed or moving bed mode, and the space velocity (namely, the gas volume which can be treated in 1 hour per cubic meter of adsorbent) used is 2000-^-1When the deposition amount of the mercury diselenide chloride on the substrate material reaches 50g/kg or more, it is necessary to take out the substrate material and regenerate it.

The third step: when the selenium dioxide or HCl in the flue gas is insufficient, the surface of the substrate can be continuously modified, the content of chlorine or selenium on the surface of the substrate is increased, and the phenomena of escape and secondary pollution caused by directly spraying the substances into the flue gas are avoided;

the selenium dioxide is insufficient when the concentration of the selenium dioxide in the smoke is lower than 200mg/m³When in use, selenium-enriched conditioning modification is needed to be carried out on the surface of the matrix material, the matrix material is subjected to impregnation modification by using 5-20% sodium selenite solution, so that the material is loaded with 1-5% of selenium (by mass of elemental selenium), and the material can be used after being dried.

The HCl deficiency refers to the condition that the HCl concentration in the flue gas is lower than 50mg/m³When in use, the surface of the matrix material needs to be modified by chlorination and tempering, the matrix material is soaked and modified by 5-10% sodium chloride solution, so that the material is loaded with 0.5-2% chlorine (by mass of elemental chlorine), and the material can be used after being dried.

The fourth step: when the chlorine selenium mercury on the surface of the substrate material is accumulated to a certain amount, the chlorine selenium mercury is taken out from the flue gas, and the regenerated mercury and selenium are respectively collected and recovered by a condensation method by utilizing a heating regeneration method. And modifying the surface of the regenerated matrix material. Can be recycled. By the method, mercury and selenium in the flue gas can be fully recycled, and the problems of secondary pollution of mercury and the like are solved. The residual flue gas enters a washing system 4 for preparing acid.

The heating regeneration method comprises the steps of heating the substrate material deposited with the chlorine selenium mercury 3 to 300-400 ℃ under the protection of nitrogen to obtain high-concentration zero-valent mercury and selenium elemental gas, and respectively recovering zero-valent mercury and selenium elemental products through step-by-step cooling condensation and adsorption. The regenerated matrix material 2 can be recycled after cooling and appropriate thermal refining modification.

Example 1

A preparation method of a selenium-enriched and tempered matrix material and a mercury capture experiment comprise the following steps:

1) preparing 0,0.1,0.25,0.5,1mol/L of Na₂SeO₃A solution;

2) weighing 100g of 1-2mm Al₂O₃Respectively adding 75mL of the solution into the pellets, performing ultrasonic treatment for 1h, and drying at 80 ℃ for 12h to obtain a selenium-enriched material;

3) 0.5g of the material was weighed into a 10mm quartz reaction tube, and the inlet Hg was controlled⁰The concentration is 1.2mg/m³,SO₂Concentration 5%, H₂O content 4%, O₂The content is 10 percent, the total flow is 300mL/min, and the reaction temperature is 80 ℃;

4) when HCl is not added, with NaSeO₃Increase in the proportion of load, Hg⁰The removal efficiency of 3h is respectively 5%, 23%, 36%, 48% and 67%;

5) when 100ppm HCl was added, with NaSeO₃Increase in the proportion of load, Hg⁰The removal efficiencies of 3h were 12%, 55%, 78%, 83%, 96%, respectively.

Example 2

A preparation method of a matrix material for chlorination refining and a mercury capture experiment comprise the following steps:

1) preparing 0,0.1,0.25,0.5,1mol/L NaCl solution;

2) weighing 100g of 1-2mm Al₂O₃Respectively adding 75mL of the solution into the pellets, performing ultrasonic treatment for 1h, and drying at 80 ℃ for 12h to obtain a chlorination material;

4) when no SeO is added₂Hg of mercury⁰The removal efficiency of 3 hours is lower than 10 percent

5) When 300mg/m is added³ SeO₂In time, Hg was increased with increasing NaCl load ratio⁰The removal efficiencies of 3h were 46%, 68%, 79%, 88%, 97%, respectively.

Example 3

A preparation method of a matrix material for simultaneous selenium and chlorine increasing and tempering and a mercury capture experiment comprise the following steps:

1) 0.01mol of NaSeO is weighed respectively₃,0.0075mol NaSeO₃+0.0025mol NaCl，0.005mol NaSeO₃+0.005mol NaCl，0.0025mol NaSeO₃+0.0075mol of NaCl, 0.01mol of NaCl, adding 15mL of deionized water, and ultrasonically dissolving;

2) respectively weighing 20 g of Al with the thickness of 1-2mm₂O₃Adding the pellets into the solution, performing ultrasonic treatment for 1h, and drying at 80 ℃ for 12h to obtain the selenium and chlorine increasing material;

3) 0.5g of the material was weighed into a 10mm quartz reaction tube, and the inlet Hg was controlled⁰The concentration is 1.2mg/m³,H₂O content 4%, O₂The content is 10 percent, the total flow is 300mL/min, and the reaction temperature is 80 ℃;

4) when SO is not added₂Hg of mercury⁰The removal efficiency of the catalyst is lower than 5 percent

5) When 5000ppm SO was added₂Hg with increasing Se/Cl ratio⁰The removal efficiencies of 3h were 53%, 68%, 85%, 99%, 30%, respectively.

Claims

1. a method for capturing mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition, is characterized in that, comprises the following steps:

(1) After the original non-ferrous smelting flue gas is dedusted and recovered by waste heat, a certain amount of water mist is sprayed into it to reduce the temperature to near the dew point, so that the selenium dioxide in the flue gas is under the combined action of sulfur dioxide and water vapor. It is reduced to active elemental selenium that can react rapidly with mercury in flue gas, and under the action of HCl in flue gas, it generates chloroselenomercuric compounds that are easy to deposit;

(2) Then, the flue gas is brought into contact with the matrix material, and through its surface induction effect, the formation and deposition of mercury chloride selenide are accelerated, so that the mercury in the flue gas is trapped on the surface of the matrix.

2. a kind of method for capturing mercury from sulfur-containing mercury-containing flue gas by chlorine selenide mercury deposition according to claim 1, is characterized in that, in non-ferrous smelting original flue gas, contains mercury, sulfur oxides, selenium dioxide and hydrogen chloride;

After the upstream flue gas dedusting and waste heat recovery, the temperature of the flue gas drops below 250 °C. The mercury in the flue gas mainly exists in the form of zero-valent mercury, and its concentration ranges from 0.1 to 50 mg/m ³ , and the concentration of SO ₂ is 0.2. %-5%, SeO ₂ concentration is 100-2000 mg/m ³ , HCl concentration is 20-500 mg/m ³ .

3. a kind of method of trapping mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition according to claim 1, is characterized in that, in step (1), spray water mist into flue gas and use efficient atomization The nozzle sprays water evenly into the flue gas, reducing the temperature of the flue gas to a level 5-10°C higher than its dew point temperature;

The water used for spraying into the water mist is process water, or acid waste water without particulate matter.

4. a kind of method for capturing mercury from sulfur-containing mercury-containing flue gas by chlorine selenide mercury deposition according to claim 1, is characterized in that, when flue gas temperature drops near dew point in step (1), smoke The selenium dioxide in the gas is rapidly reduced to active elemental selenium by sulfur dioxide, and the reduction rate of selenium dioxide is more than 10%; through the joint action of HCl in the flue gas, the gas-phase zero-valent mercury is converted into chloroselenomercury, and the gas-phase conversion rate of mercury up to 5-20%.

5. a kind of method for capturing mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition according to claim 1, is characterized in that, the matrix material described in step (2) is metal oxide or porous material;

The metal oxides include aluminum oxide, zinc oxide, titanium dioxide or iron oxide;

The porous material is activated carbon or silica.

6. a kind of method of trapping mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition according to claim 1, is characterized in that, the contact mode that flue gas contacts with host material in step (2) is:

The matrix material is directly sprayed into the flue gas in the form of 100-300 mesh powder,

Or the matrix material is prepared into spherical or columnar particles with a diameter of 2-10 mm, and is contacted with the flue gas in the form of a fixed bed or a moving bed.

7. a kind of method of trapping mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition according to claim 1, is characterized in that, step (2) promotes flue gas mercury by the surface induction of host material For further conversion to mercury selenochloride, the total conversion efficiency is greater than 80%.

8. a kind of method for capturing mercury from sulfur-containing mercury-containing flue gas by chlorine selenide mercury deposition according to claim 1, is characterized in that, when the selenium dioxide or HCl in the flue gas is insufficient, to the host material The surface is modified to increase the content of chlorine or selenium on the surface to avoid escape and secondary pollution caused by directly spraying these substances into the flue gas.

9. a kind of method for trapping mercury from sulfur-containing mercury-containing flue gas by chlorine selenide mercury deposition according to claim 8, it is characterized in that, when the selenium dioxide concentration in the flue gas itself is lower than 200mg/ ^m time , Impregnate and modify the matrix material with 5-20% sodium selenite solution, so that the material is loaded with 1-5% selenium, based on the mass of elemental selenium, it can be used after drying;

When the HCl concentration in the flue gas itself is lower than 50mg/ ^m3 , the matrix material is impregnated and modified with 5-10% sodium chloride solution, so that the material is loaded with 0.5-2% chlorine, based on the mass of elemental chlorine, air-dried can be used afterwards.

10. a kind of method for capturing mercury from sulfur-containing mercury-containing flue gas by chloroselenomercuric deposition according to claim 1, is characterized in that, when the chloroselenomercuric on the surface of the host material accumulates to a certain amount, then It is taken out from the flue gas, and the regenerated mercury and selenium are collected and recovered respectively by the method of heating and regeneration by the condensation method, and the regenerated matrix material can be recycled after surface conditioning and modification.