Method for continuously treating calcium-containing wastewater by utilizing volatile kiln flue gas

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a method for continuously treating calcium-containing wastewater by utilizing volatile kiln flue gas. The method comprises the following steps: S1, adjusting the pH value of calcium-containing wastewater to 8-14 through a pH regulator, conveying the calcium-containing wastewater to a decalcification reaction unit from a wastewater storage tank in a spraying or injection manner, feeding volatile kiln flue gas into the decalcification reaction unit through an aeration device, and carrying out a decalcification reaction on the calcium-containing wastewater and the volatile kiln flue gas to obtain mixed slurry, residual gas is discharged after being detected to be qualified through the tail gas discharging unit; s2, the mixed slurry obtained in the step S1 is pumped into a solid-liquid separation unit for solid-liquid separation, and calcium carbonate solids and decalcified liquid are obtained. The method provided by the invention solves the problem that the calcium-containing wastewater and the carbon dioxide in the flue gas need to be treated separately, realizes cooperative treatment of the flue gas and the wastewater, and has the advantages of simplicity and convenience in operation, low treatment cost, simple system and the like.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for continuously treating calcium-containing wastewater using volatile matter kiln flue gas. Background Technology

[0002] A volatile matter kiln is a rotary kiln used to process valuable metals in leaching slag during hydrometallurgical processes. It separates and volatilizes metals through a high-temperature volatilization reaction, followed by condensation in the flue gas. The flue gas produced by the volatile matter kiln is rich in carbon dioxide, sulfur dioxide, and nitrogen oxides. These pollutants directly contribute to air pollution, affecting air quality and exacerbating smog. Simultaneously, non-ferrous metal smelting processes also generate calcium-containing wastewater, primarily composed of calcium sulfate and sodium sulfate, which requires treatment before discharge. Therefore, combining the flue gas from the volatile matter kiln with the calcium-containing wastewater not only captures carbon dioxide and sulfur dioxide from the flue gas through the wastewater but also reduces the calcium content in the wastewater by generating calcium carbonate precipitate, thus achieving the goal of treating waste with waste. Summary of the Invention

[0003] This invention provides a method for treating calcium-containing wastewater using volatile matter kiln flue gas, which can effectively suppress the effect of sulfur dioxide on the pH value of wastewater, thereby improving the calcium-containing wastewater's ability to absorb carbon dioxide.

[0004] Traditional methods can only treat alkaline wastewater containing hydroxides, while calcium-containing wastewater generated during smelting is neutral or even weakly acidic wastewater containing sulfates, affecting its ability to absorb carbon dioxide and reduce calcium content. Specifically, the inventors discovered that the flue gas from the volatilization kiln contains various gases such as carbon dioxide, sulfur dioxide, and nitrogen oxides. The presence of sulfur dioxide significantly hinders the capture of carbon dioxide by the calcium-containing wastewater, resulting in poor absorption. Furthermore, the types and concentrations of ions in the calcium-containing wastewater also affect the absorption effect. Through extensive research, the inventors found that adjusting the pH and decalcification reaction time of the calcium-containing wastewater can effectively suppress the influence of sulfur dioxide on the pH value, thereby significantly improving the carbon dioxide absorption capacity of the calcium-containing wastewater.

[0005] Specifically, a method for continuously treating calcium-containing wastewater using volatile matter kiln flue gas includes:

[0006] Step S1: The pH of the calcium-containing wastewater is adjusted to 8-14 using a pH adjuster. The wastewater is then transported from the wastewater storage tank to the decalcification reaction unit via spraying or injection. The flue gas from the volatilization kiln is fed into the decalcification reaction unit through an aeration device. The calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction to obtain a mixed slurry (containing calcium carbonate and post-reaction liquid). The remaining gas (i.e. the remaining flue gas from the volatilization kiln) is discharged through the tail gas discharge unit after passing the test.

[0007] Step S2: The mixed slurry described in step S1 is fed into a solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid.

[0008] Specifically, the method for continuously treating calcium-containing wastewater using volatile matter kiln flue gas further includes:

[0009] In step S3, the calcium carbonate solid produced in step S2 is stored in a stack, and the decalcified liquid is temporarily stored in a decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0010] Specifically, the calcium-containing wastewater mentioned in step S1 is a solution of metal sulfates such as sodium sulfate, calcium sulfate, and zinc sulfate produced in lead-zinc smelters during processes such as flue gas purification, zinc smelting purification, wastewater treatment, and slag treatment. The calcium-containing wastewater contains calcium sulfate. 2+ The content is 0.1-0.6 g / L, Na + The content is 0-10 g / L, Zn 2+ The concentration is 0–5 g / L. In addition, the solution also contains small amounts of metal ions such as magnesium, aluminum, and potassium, with concentrations ranging from 0 to 0.5 g / L.

[0011] Specifically, the pH adjuster mentioned in step S1 is a hydroxide solid or solution such as calcium hydroxide, sodium hydroxide, or potassium hydroxide. In some specific embodiments, the pH of the calcium-containing wastewater is adjusted to 8, 9, 10, 11, 12, 13, or 14, preferably pH 11-14.

[0012] Specifically, the flue gas from the volatilization kiln mentioned in step S1 mainly originates from the volatilization kiln of the lead-zinc smelter, and its components include CO2, SO2, and NO. x The concentrations of CO2, SO2, and O2 range from 500 to 50,000 ppm, respectively, with NO content also being relatively high. x The concentration is 0-500 ppm. The aeration device includes micropores, sprayers, aeration pipes, etc.

[0013] Specifically, the SO2 content in the flue gas from the volatilization cellar in step S1 is 270-1300 ppm.

[0014] Specifically, in step S1, the time for the calcium-containing wastewater to undergo decalcification reaction with the flue gas from the volatilization kiln is 5-30 minutes, preferably 10-15 minutes.

[0015] In some specific embodiments, in step S1, the pH of the adjusted wastewater is 11-14, the SO2 content in the volatile matter kiln flue gas is 270-1300 ppm, and the time for the calcium-containing wastewater to undergo decalcification reaction with the volatile matter kiln flue gas is 10-15 min.

[0016] This invention discovers that when the SO2 content in the flue gas from the volatilization pit is high, for example, at 800-1300 ppm, the increase in sulfur dioxide content leads to a decrease in the pH value of calcium-containing wastewater, which in turn reduces the absorption efficiency of calcium-containing wastewater for carbon dioxide. This invention can effectively suppress the influence of sulfur dioxide on the pH value of wastewater by reducing the reaction time and increasing the initial pH value of the wastewater, thereby improving the absorption capacity of calcium-containing wastewater for carbon dioxide.

[0017] Specifically, step S1 also includes:

[0018] When the calcium ion concentration in the decalcification reaction unit is greater than the set value, the solution discharge from the decalcification reaction unit is stopped by the switch control unit, and the wastewater flow rate is increased by the wastewater flow control unit.

[0019] When the calcium ion concentration in the decalcification reaction unit is less than the set value, the solid-liquid mixture solution after decalcification and acid-base neutralization reaction is discharged from the decalcification reaction unit and enters the solid-liquid separation unit.

[0020] Specifically, the set value is a calcium ion concentration of 0.08-0.2 g / L.

[0021] In some specific embodiments, the initial calcium ion concentration in the decalcification reaction unit is about 0.4-0.5 g / L. As the reaction proceeds, the calcium ion concentration first decreases to 0.08 g / L or below. The reaction continues until the calcium ion content rises again to above 0.08-0.2 g / L, and then enters the solid-liquid separation unit.

[0022] Specifically, the final pH value of the calcium-containing wastewater in the decalcification reaction unit described in step S1 is 6.5-9. If the final pH value of the calcium-containing wastewater is less than 6.5, the pH of the calcium-containing wastewater needs to be adjusted by adding a pH adjuster until the pH is greater than 7.5, and the unqualified flue gas after absorption is discharged into the volatilization kiln.

[0023] Specifically, in step S1, the remaining gas is discharged through the tail gas discharge unit. The tail gas after the reaction is discharged through the tail gas discharge unit. After passing the test, it is directly discharged to the outside. If it fails the test, it needs to be discharged into the volatilization kiln and discharged only after it passes the test.

[0024] Specifically, the solid-liquid separation unit in step S2 involves solid-liquid separation devices such as filter presses, centrifugal dewatering machines, and filter cake dewatering machines.

[0025] This invention utilizes calcium-containing wastewater containing calcium sulfate and sodium sulfate generated during the smelting process to co-treat the flue gas from the volatilization kiln, thereby achieving the goal of treating waste with waste. It solves the problem that calcium-containing wastewater and carbon dioxide in the flue gas need to be treated separately, and realizes the co-treatment of flue gas and wastewater. It has the advantages of simple operation, low treatment cost, and simple system. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the method of an embodiment of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] With regard to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0033] The following examples illustrate a method for continuously treating calcium-containing wastewater using volatile matter kiln flue gas. Please refer to the flowchart below. Figure 1 .

[0034] Example 1

[0035] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.498 g / L, Na + 7.12 g / L, Zn 2+ 0.69 g / L. The volatile matter kiln flue gas contained 26223 ppm CO2, 271 ppm SO2, 507 ppm O2, and NO... x The content is 3.4 ppm.

[0036] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0037] 1. After adjusting the pH of the calcium-containing wastewater to 12 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 20 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7.5) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 95.26%, and it is discharged through the gas discharge unit.

[0038] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0039] Tests showed that the calcium content in the decalcified solution decreased to 0.04 g / L, the carbon dioxide absorption rate was 95.26%, and the sulfur dioxide absorption rate was 98.9%.

[0040] Example 2

[0041] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter kiln flue gas contained 27265 ppm CO2, 813 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0042] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0043] 1. After adjusting the pH of the calcium-containing wastewater to 12 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent to the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 20 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=6.5) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 78.54%, and it is discharged through the gas discharge unit.

[0044] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0045] Tests showed that the calcium content in the decalcified solution decreased to 0.13 g / L, the carbon dioxide absorption rate was 78.54%, and the sulfur dioxide absorption rate was 97.6%.

[0046] Example 3

[0047] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.525 g / L, Na + 8.46 g / L, Zn 2+ 0.85 g / L. The volatile matter content of the flue gas from the volatilization kiln was 23847 ppm CO2, 1023 ppm SO2, 876 ppm O2, and NO... x The content was 12.9 ppm.

[0048] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0049] 1. After adjusting the pH of the calcium-containing wastewater to 12 with calcium hydroxide, it is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent to the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the volatilization kiln flue gas undergo a decalcification reaction for 20 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=6) is obtained. The remaining gas is tested and the carbon dioxide absorption rate is only 55.62%. It is then sent back to the volatilization kiln through the gas discharge unit. The pH of the calcium-containing wastewater is adjusted to 7.5 with sodium hydroxide.

[0050] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0051] Tests showed that the calcium content in the decalcified solution decreased to 0.08 g / L, the carbon dioxide absorption rate was 55.62%, and the sulfur dioxide absorption rate was 75.26%.

[0052] As can be seen from Examples 1, 2, and 3, an increase in sulfur dioxide content leads to a decrease in the pH value of calcium-containing wastewater, which in turn reduces the absorption efficiency of carbon dioxide by the calcium-containing wastewater. High sulfur dioxide content in the volatile matter kiln flue gas causes the pH of calcium-containing wastewater to be too low, preventing calcium from adsorbing carbon dioxide. Adding sodium hydroxide can only reduce the calcium ion content in the calcium-containing wastewater; it cannot increase the carbon dioxide adsorption capacity.

[0053] Example 4

[0054] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter content of the flue gas from the volatilization kiln was 27265 ppm CO2, 1023 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0055] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0056] 1. After adjusting the pH of the calcium-containing wastewater to 12 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 10 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 90.67%, and it is discharged through the gas discharge unit.

[0057] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0058] Tests showed that the calcium content in the decalcified solution decreased to 0.10 g / L, the carbon dioxide absorption rate was 90.67%, and the sulfur dioxide absorption rate was 98.24%.

[0059] Example 5

[0060] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+0.73 g / L. The volatile matter content of the flue gas from the volatilization kiln was 27265 ppm CO2, 1023 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0061] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0062] 1. After adjusting the pH of the calcium-containing wastewater to 14 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 20 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=6.8) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 85.96%, and it is discharged through the gas discharge unit.

[0063] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0064] Tests showed that the calcium content in the decalcified solution decreased to 0.12 g / L, the carbon dioxide absorption rate was 85.96%, and the sulfur dioxide absorption rate was 97.61%.

[0065] Example 6

[0066] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter content of the flue gas from the volatilization kiln was 27265 ppm CO2, 1023 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0067] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0068] 1. After adjusting the pH of the calcium-containing wastewater to 14 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 10 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7.8) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 98.37%, and it is discharged through the gas discharge unit.

[0069] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0070] Tests showed that the calcium content in the decalcified solution decreased to 0.04 g / L, the carbon dioxide absorption rate was 98.37%, and the sulfur dioxide absorption rate was 99.96%.

[0071] As can be seen from Examples 3-6, both reducing the reaction time and increasing the initial pH value of the wastewater can effectively suppress the effect of sulfur dioxide on the pH value of the wastewater. However, if both conditions are present simultaneously, the effect of sulfur dioxide on the pH value of the wastewater can be suppressed more effectively.

[0072] Example 7

[0073] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.525 g / L, Na + 8.46 g / L, Zn 2+ 0.85 g / L. The volatile matter content of the flue gas from the volatilization kiln was 23847 ppm CO2, 1023 ppm SO2, 876 ppm O2, and NO... x The content was 12.9 ppm.

[0074] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0075] 1. After adjusting the pH of the calcium-containing wastewater to 14 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent to the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 15 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7.5) is obtained. The remaining gas is tested and the carbon dioxide absorption rate is 94.57%, and it is discharged through the gas discharge unit.

[0076] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0077] Tests showed that the calcium content in the decalcified solution decreased to 0.06 g / L, the carbon dioxide absorption rate was 94.57%, and the sulfur dioxide absorption rate was 98.74%.

[0078] Example 8

[0079] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+0.525 g / L, Na + 8.46 g / L, Zn 2+ 0.85 g / L. The volatile matter content of the flue gas from the volatilization kiln was 23847 ppm CO2, 1023 ppm SO2, 876 ppm O2, and NO... x The content was 12.9 ppm.

[0080] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0081] 1. After adjusting the pH of the calcium-containing wastewater to 12 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 5 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7) is obtained. The remaining gas is tested and the carbon dioxide absorption rate is only 88.79%, and it is discharged through the gas discharge unit.

[0082] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0083] Tests showed that the calcium content in the decalcified solution decreased to 0.07 g / L, the carbon dioxide absorption rate was 88.79%, and the sulfur dioxide absorption rate was 95.26%.

[0084] As can be seen from Examples 3-8, reducing the reaction time and increasing the initial pH value of the wastewater can effectively suppress the effect of sulfur dioxide on the pH value of the wastewater, thereby improving the absorption capacity of calcium-containing wastewater for carbon dioxide.

[0085] Example 9

[0086] In this embodiment, the ion content of calcium-containing wastewater is Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter kiln flue gas contained 27265 ppm CO2, 813 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0087] This embodiment provides a method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0088] 1. After adjusting the pH of the calcium-containing wastewater to 13 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 10 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=7.3) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 96.26%, and it is discharged through the gas discharge unit.

[0089] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0090] Tests showed that the calcium content in the decalcified solution decreased to 0.05 g / L, the carbon dioxide absorption rate was 96.26%, and the sulfur dioxide absorption rate was 98.53%.

[0091] As can be seen from Examples 2 and 9, increasing the pH of calcium-containing wastewater and reducing the decalcification reaction time can effectively suppress the effect of sulfur dioxide on the pH value of wastewater, thereby improving the absorption capacity of calcium-containing wastewater for carbon dioxide.

[0092] Comparative Example 1

[0093] The calcium-containing wastewater in this comparative example has an ion content of Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter kiln flue gas contained 27265 ppm CO2, 813 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0094] This comparative example describes a method for the continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0095] 1. After adjusting the pH of the calcium-containing wastewater to 13 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 5 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=8) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 99.48%, and it is discharged through the gas discharge unit.

[0096] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0097] Tests showed that the calcium content in the decalcified solution decreased to 0.13 g / L, the carbon dioxide absorption rate was 99.48%, and the sulfur dioxide absorption rate was 99.13%.

[0098] As can be seen from Comparative Example 1, a reaction time that is too short will prevent calcium ions in the decalcified solution from reacting fully with carbon dioxide, resulting in incomplete removal.

[0099] Comparative Example 2

[0100] The calcium-containing wastewater in this comparative example has an ion content of Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn 2+ 0.73 g / L. The volatile matter kiln flue gas contained 27265 ppm CO2, 1296 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0101] This comparative example describes a method for the continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0102] 1. After adjusting the pH of the calcium-containing wastewater to 13 with calcium hydroxide, it is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent to the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 15 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=5.5) is obtained. The remaining gas is tested and the carbon dioxide absorption rate is only 35.74%. It is then sent back to the volatilization kiln through the gas discharge unit, and the pH of the calcium-containing wastewater is adjusted to 7.5 with sodium hydroxide.

[0103] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0104] Tests showed that the calcium content in the decalcified solution decreased to 0.09 g / L, the carbon dioxide absorption rate was 35.74%, and the sulfur dioxide absorption rate was 56.89%.

[0105] As can be seen from Comparative Example 2, excessively high sulfur dioxide concentrations can prevent calcium ions in the decalcified liquid from absorbing carbon dioxide in the flue gas, resulting in the failure of the wastewater absorption effect.

[0106] Comparative Example 3

[0107] The calcium-containing wastewater in this comparative example has an ion content of Ca. 2+ 0.512 g / L, Na + 8.35 g / L, Zn2+ 0.73 g / L. The volatile matter kiln flue gas contained 27265 ppm CO2, 1296 ppm SO2, 1025 ppm O2, and NO... x The content is 10.2 ppm.

[0108] This comparative example provides a method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln, including:

[0109] 1. After adjusting the pH of the calcium-containing wastewater to 13 with calcium hydroxide, the wastewater is injected from the wastewater storage tank to the decalcification reaction unit. The flue gas from the volatilization kiln is sent into the decalcification reaction unit through an aeration device. After the calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction for 8 minutes, a mixed slurry (i.e., calcium carbonate and reaction liquid, pH=6.8) is obtained. The remaining gas is tested and the carbon dioxide absorption rate reaches 90.47%, and it is discharged through the gas discharge unit.

[0110] 2. The mixed slurry described in step 1 is fed into the solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid. The calcium carbonate solid is stored by stacking, and the decalcified liquid is temporarily stored in the decalcified liquid storage tank and then enters the wastewater treatment system along with other waste liquids.

[0111] Tests showed that the calcium content in the decalcified solution decreased to 0.09 g / L, the carbon dioxide absorption rate was 90.47%, and the sulfur dioxide absorption rate was 96.24%.

[0112] As can be seen from Comparative Examples 2 and 3, for flue gas with excessive sulfur dioxide, reducing the reaction time can effectively improve the absorption of carbon dioxide and sulfur dioxide by calcium-containing waste liquid.

[0113] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for continuously treating calcium-containing wastewater using flue gas from a volatilization kiln, characterized in that, include: Step S1: The pH of the calcium-containing wastewater is adjusted to 8-14 using a pH adjuster. The wastewater is then transported from the wastewater storage tank to the decalcification reaction unit via spraying or injection. The flue gas from the volatilization kiln is sent into the decalcification reaction unit via an aeration device. The calcium-containing wastewater and the flue gas from the volatilization kiln undergo a decalcification reaction to obtain a mixed slurry. The remaining gas is discharged through the tail gas discharge unit after passing the test. Step S2: The mixed slurry described in step S1 is fed into a solid-liquid separation unit for solid-liquid separation to obtain calcium carbonate solid and decalcified liquid.

2. The method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to claim 1, characterized in that, The calcium-containing wastewater mentioned in step S1 is a metal sulfate solution produced by a lead-zinc smelter during the flue gas purification, zinc smelting purification, wastewater treatment, and slag treatment processes. Optionally, the calcium-containing wastewater contains Ca 2+ The content is 0.1-0.6 g / L, Na + The content is 0-10 g / L, Zn 2+ The content is 0-5 g / L.

3. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to claim 1 or 2, characterized in that, The pH adjuster mentioned in step S1 is calcium hydroxide, sodium hydroxide, or potassium hydroxide; Optionally, the pH of the calcium-containing wastewater can be adjusted to 8, 9, 10, 11, 12, 13 or 14, preferably pH 11-14.

4. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-3, characterized in that, The flue gas from the volatilization kiln mentioned in step S1 mainly originates from the volatilization kiln of the lead-zinc smelter, and its components include CO2, SO2, and NO. x ; Optionally, the CO2 content of the flue gas from the volatilization pit is 500-50000 ppm, the SO2 content is 270-5000 ppm, the O2 content is 500-10000 ppm, and the NO content is... x The content ranges from 0 to 500 ppm.

5. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-4, characterized in that, The SO2 content in the flue gas from the volatilization kiln in step S1 is 270-1300 ppm; and / or, the time for the decalcification reaction between the calcium-containing wastewater and the flue gas from the volatilization kiln in step S1 is 5-30 min, preferably 10-15 min.

6. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-5, characterized in that, Step S1 also includes: When the calcium ion concentration in the decalcification reaction unit is greater than the set value, the solution discharge from the decalcification reaction unit is stopped by the switch control unit, and the wastewater flow rate is increased by the wastewater flow control unit. When the calcium ion concentration in the decalcification reaction unit is less than the set value, the solid-liquid mixture solution after the decalcification and acid-base neutralization reaction is discharged from the decalcification reaction unit and enters the solid-liquid separation unit. Preferably, the set value is a calcium ion concentration of 0.08-0.2 g / L.

7. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-6, characterized in that, The final pH value of the calcium-containing wastewater in the decalcification reaction unit in step S1 is 6.5-9. If the final pH value of the calcium-containing wastewater is less than 6.5, the pH of the calcium-containing wastewater needs to be adjusted by adding a pH adjuster until the pH is greater than 7.5, and the unqualified flue gas after absorption is discharged into the volatilization kiln.

8. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-7, characterized in that, The step S1, in which the remaining gas is discharged through the tail gas discharge unit, involves leading the reacted tail gas out through the tail gas discharge unit. After passing the test, the gas is directly discharged to the outside. If the gas fails the test, it needs to be discharged into the volatilization kiln and discharged only after passing the test.

9. A method for continuous treatment of calcium-containing wastewater using flue gas from a volatilization kiln according to any one of claims 1-8, characterized in that, The solid-liquid separation unit in step S2 involves a filter press, a centrifugal dewatering machine, or a filter cake dewatering machine.

Images