Method for removing mercury from pyrometallurgical flue gas by vulcanization method

Abstract

The present invention relates to the technical field of removal of mercury from flue gas, and in particular to a method for removing mercury from pyrometallurgical flue gas by a vulcanization method. The method for removing mercury from pyrometallurgical flue gas by the vulcanization method in the present invention comprises: using an atomized soluble sulfide aqueous solution as a mercury removal agent; and spraying the mercury removal agent into a flue between a dry dust removal device and a flue gas washing device or a wet dust removal device, wherein when the temperature of flue gas in the flue is higher than 120°C, a gas phase reaction occurs between the mercury removal agent and the flue gas so as to convert mercury in the flue gas into mercury sulfide. The use of the method in the present invention to perform mercury removal treatment on smelting flue gas achieves a good mercury removal effect, and achieves direct connection with an original technological process at the same time; in addition, raw materials of a reagent for mercury removal are easily available, and the addition amount of the mercury removal agent is extremely low, so that the overall mercury removal treatment cost is lower.

Description

A method for removing mercury from pyrometallurgical flue gas by sulfidation Technical Field

[0001] The present invention belongs to the technical field of flue gas mercury removal, and in particular relates to a method for removing mercury from pyrometallurgical flue gas by using a sulfidation method. Background Art

[0002] Mercury, as a very harmful heavy metal pollutant, exists in many metallurgical mineral resources. Most zinc ores, lead ores, some copper ores, and even gold ores and pyrite ores contain mercury. There are three forms of Hg in flue gas: elemental mercury (Hg 0 ), oxidized mercury, and particulate mercury. Particulate mercury and oxidized mercury can be efficiently removed using dust collectors and wet desulfurization equipment, respectively. However, elemental mercury is highly volatile and insoluble in water, making it difficult to directly remove using existing flue gas treatment equipment. Therefore, efficiently removing elemental mercury from flue gas has always been a key and difficult issue for the industry.

[0003] The prior art publication number CN109012091B is "A Synergistic Removal of Hg from Flue Gas" 0 and Hg in wastewater 2+ The technical solution of the invention is to use metal sulfide (CuFeS2) as a mercury removal adsorbent, and spray the adsorbent into the flue before the dry dust removal device or the wet dust removal device / demisting device. The adsorbent contacts the flue gas, thereby adsorbing and removing Hg in the flue gas. 0 This technical solution relies on the demercuration adsorbent to remove Hg in the flue gas. 0 Carry out adsorption removal.

[0004] Furthermore, in this technical solution, the BET specific surface area of ​​the metal sulfide is required to be greater than 2.5 m 2 / g, and the particle size is between 10-300 mesh; at the same time, in this technical solution, when the demercuration adsorbent is added to the flue before the dry dust removal device for demercuration, the flue gas temperature is 60°C-200°C; the mass ratio of the demercuration adsorbent to mercury in the flue gas is 600:1-100000:1; when the demercuration adsorbent is added to the flue before the wet desulfurization device for demercuration, the flue gas temperature is 60°C-150°C, and the mass ratio of the demercuration adsorbent to mercury in the flue gas is 500:1-100000:1

[0005] However, in actual production operations, since the temperature of flue gas discharged from pyrometallurgy is usually high, the temperature after exiting dry dust removal devices such as electrostatic precipitators is generally between 250-400°C. If it is before dry dust removal, the temperature of the flue gas will be correspondingly higher. Therefore, the above technical solution requires controlling the flue gas temperature to be lower (60°C-200°C) for mercury removal to reduce the reaction process and time. At the same time, in order to ensure better adsorption and removal effects, the mercury removal adsorbent in the above technical solution also has high quality requirements for the mercury removal adsorbent itself. It is not easy to obtain a CuFeS2 finished product that meets the requirements; and if it is synthesized on site, certain preparation conditions must be controlled before it can be prepared. In addition, the above technical solution also has the problem of high consumption of mercury removal adsorbent.

[0006] Therefore, how to ensure the demercuration effect while reducing the operating cost when removing mercury from pyrometallurgical flue gas has always been a technical problem that needs to be solved urgently by those skilled in the art.

[0007] Summary of the Invention

[0008] To overcome the problems existing in the background art, the present invention provides a method for removing mercury from pyrometallurgical flue gas by sulfidation, which has a good demercuration effect and can be directly connected with the existing process flow. In addition, the reagent raw materials used for demercuration are readily available, and the amount of demercuration agent added is extremely low, thereby reducing the overall demercuration treatment cost.

[0009] To achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A method for removing mercury from pyrometallurgical flue gas by sulfidation, using an atomized soluble sulfide aqueous solution as a mercury removal agent; the mercury removal agent is sprayed into a flue between a dry dust removal device and a flue gas scrubber or a wet dust removal device; under the condition that the flue gas temperature in the flue is greater than 120°C, the mercury removal agent reacts with the flue gas in a gas phase to convert the mercury in the flue gas into mercury sulfide.

[0011] Specifically, the soluble sulfide is at least one of sodium sulfide, sodium hydrosulfide, potassium sulfide or potassium hydrosulfide.

[0012] Specifically, the mass ratio of the soluble sulfide to mercury in the flue gas is 2.8-10:1.

[0013] Specifically, the flue gas temperature is 120-350° C. It should be noted that the minimum temperature of the flue gas is controlled at least above 120° C. in order to ensure the smooth progress of the gas phase reaction.

[0014] Specifically, the aqueous solution of soluble sulfide is replaced by hydrogen sulfide gas. When hydrogen sulfide gas is used, atomization is omitted and the gas can be directly sprayed.

[0015] It should be noted that the pyrometallurgical flue gas in the present invention refers to the flue gas generated during the pyrometallurgical smelting process of copper smelting, lead smelting and tin smelting. After passing through the dry dust removal device (electrostatic precipitator), its temperature is generally between 200-400°C.

[0016] Beneficial effects of the present invention:

[0017] 1. The present invention uses an atomized aqueous solution of soluble sulfide as a mercury removal agent. Compared to the prior art that uses expensive CuFeS2 as a mercury removal adsorbent, the raw materials are cheap and readily available, and there is no need to control the specific surface area and particle size. Industrial-grade soluble sulfide raw materials can be directly used. At the same time, because the atomized aqueous solution of soluble sulfide in the present invention contacts the mercury in the flue gas more fully and quickly, the mass ratio of the mercury removal agent to the mercury in the flue gas is extremely low when the atomized aqueous solution of soluble sulfide is used as the mercury removal agent. Compared to the prior art that uses CuFeS2 as a mercury removal adsorbent, the mass ratio of the mercury removal adsorbent to the mercury in the flue gas is 500:1-100,000:1, while the mass ratio of the soluble sulfide to the mercury in the flue gas in the present invention is only 2.8-10:1, greatly reducing the consumption of reagents. In addition, the soluble sulfide in the present invention is more affordable than CuFeS2, which is particularly suitable for smelting enterprises with large flue gas processing volumes (flue gas flow rates of up to 100,000 m3). 3 / h), with higher economic benefits.

[0018] Specifically, assuming the flue gas flow rate is 100000m 3 / h, the mercury content in the flue gas is 0.5mg / m 3 According to the prior art, using CuFeS2 as a mercury removal adsorbent requires the input of at least 600 kg of CuFeS2 per 24 hours, which is a huge consumption and high cost. However, according to the soluble sulfide of the present invention, under the same flue gas flow rate and mercury content conditions, only 4.68 kg of CuFeS2 needs to be input per 24 hours, greatly saving the consumption of mercury removal agent. As for the water for dissolving the soluble sulfide, it is more widely available and more affordable.

[0019] 2. The flue gas treated in the present invention is discharged from a dry dust removal device after dust collection. The temperature of the flue gas discharged here is generally between 200-400°C. During the mercury removal operation, the atomized mercury removal agent is directly sprayed into the flue for gas-phase reaction. The mercury removal operation in the present invention directly utilizes existing processes, which is more convenient and lowers the cost.

[0020] 3. In the present invention, the mercury removal agent reacts with mercury in the flue in a gas phase, which is more rapid and complete. At the same time, the mercury sulfide generated by the reaction has a stronger binding force. Compared with the adsorption method using an adsorbent, the bound mercury is more difficult to release again, thereby fully ensuring the effective removal rate of mercury. At the same time, because the sulfur and mercury react in the gas phase in the present invention, it can achieve efficient removal of mercury in any form. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0022] Example 1

[0023] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.5 mg / m 3 Sodium sulfide was prepared into a 5 g / L sodium sulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 330°C, the injection rate of the sodium sulfide solution was 39 L / h, and the mercury removal efficiency was measured to be 99.8%.

[0024] Example 2

[0025] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.38 mg / m 3 Sodium sulfide was prepared into a 5 g / L sodium sulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 300°C, the injection rate of the sodium sulfide solution was 74 L / h, and the mercury removal efficiency was measured to be 99.7%.

[0026] Example 3

[0027] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.1 mg / m 3Sodium sulfide was prepared into a 2 g / L sodium sulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 270°C, the injection rate of the sodium sulfide solution was 19 L / h, and the mercury removal efficiency was measured to be 97.9%.

[0028] Example 4

[0029] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.22 mg / m 3 Sodium hydrosulfide was prepared into a 3 g / L sodium hydrosulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 350°C, the injection rate of the sodium sulfide solution was 20 L / h, and the mercury removal efficiency was measured to be 99.8%.

[0030] Example 5

[0031] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.35 mg / m 3 Potassium sulfide was prepared into a 3g / L potassium sulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 300°C, the injection rate of the sodium sulfide solution was 22L / h, and the mercury removal efficiency was measured to be 99.7%.

[0032] Example 6

[0033] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.10 mg / m 3 Potassium bisulfide was prepared into a 5 g / L potassium bisulfide aqueous solution, which was atomized using an atomizing device. The atomized sodium sulfide aqueous solution was used as a mercury removal agent and then sprayed into the flue gas duct between the outlet of the electrostatic precipitator and the dynamic wave scrubber. The flue gas temperature was 300°C, the injection rate of the sodium sulfide solution was 6 L / h, and the mercury removal efficiency was measured to be 98.1%.

[0034] Example 7

[0035] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.45 mg / m 3 The hydrogen sulfide gas is injected into the flue gas duct between the outlet of the electrostatic precipitator and the power wave washing tower. The flue gas temperature is 330℃ and the injection volume of hydrogen sulfide gas is 1.9m 3 / h, and the mercury removal efficiency was determined to be 99.8%.

[0036] Example 8

[0037] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.38 mg / m 3 , inject hydrogen sulfide gas into the flue gas duct between the outlet of the electrostatic precipitator and the power wave washing tower, the flue gas temperature is 310℃, and the injection volume of hydrogen sulfide gas is 1.5m 3 / h, and the mercury removal efficiency was determined to be 99.7%.

[0038] Example 9

[0039] An experiment was conducted in a copper smelter in Yunnan, with a flue gas volume of 100,000 m 3 / h, Hg at the outlet of electrostatic precipitator 0 The concentration is 0.12 mg / m 3 , inject hydrogen sulfide gas into the flue gas duct between the outlet of the electrostatic precipitator and the power wave washing tower, the flue gas temperature is 320℃, and the injection amount of hydrogen sulfide gas is 0.4m 3 / h, and the mercury removal efficiency was determined to be 97.3%.

[0040] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for removing mercury from pyrometallurgical flue gas by sulfidation, characterized in that: The atomized soluble sulfide aqueous solution is used as a mercury removal agent; the mercury removal agent is sprayed into the flue between the dry dust removal device and the flue gas scrubber or the wet dust removal device. Under the condition that the flue gas temperature in the flue is greater than 120°C, the mercury removal agent reacts with the flue gas in the gas phase to convert the mercury in the flue gas into mercuric sulfide.

2. The method for removing mercury from pyrometallurgical flue gas by sulfidation according to claim 1, characterized in that: The soluble sulfide is at least one of sodium sulfide, sodium hydrosulfide, potassium sulfide or potassium hydrosulfide.

3. The method for removing mercury from pyrometallurgical flue gas by sulfidation according to claim 2, characterized in that: The mass ratio of the soluble sulfide to mercury in the flue gas is 2.8-10:

1.

4. The method for removing mercury from pyrometallurgical flue gas by sulfidation according to claim 1, characterized in that: The flue gas temperature is 120-350°C.

5. The method for removing mercury from pyrometallurgical flue gas by sulfidation according to claim 1, characterized in that: The aqueous solution of the soluble sulfide is replaced by hydrogen sulfide gas, and when hydrogen sulfide gas is used, atomization thereof is abandoned.