Method for mineralizing and sealing sulfur dioxide and carbon dioxide by utilizing arsenic-calcium slag

Abstract

The invention relates to the technical field of capture and storage of sulfur dioxide (SO2) and carbon dioxide (CO2), in particular to a method for mineralizing and sealing SO2 and CO2 by using arsenic-calcium slag. The method provided by the invention comprises the following steps: mixing arsenic-calcium slag with water to obtain arsenic-calcium slag slurry; mixing the gas to be treated with the arsenic-calcium slag slurry, carrying out combination reaction, and mineralizing and fixing SO2 or CO2 into a solid phase of the arsenic-calcium slag slurry; during the combination reaction, adjusting the pH value of the arsenic-calcium slag slurry to 2-13; the gas to be treated contains SO2 and / or CO2. Compared with the prior art, the method provided by the invention can effectively mineralize and fix SO2 and CO2 in a solid phase in the form of sulfate (sulfite) or carbonate (bicarbonate), has the advantages of low raw material price, simple and convenient process, integration of SO2 and CO2 trapping and storage, high additional utilization and the like, and also can realize treatment of waste with waste.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur dioxide (SO2) and carbon dioxide (CO2) capture and storage, and in particular to a method for storing SO2 and CO2 by mineralizing arsenic-calcium slag. Background Art

[0002] Large-scale emissions of CO2 will lead to a series of environmental problems such as frequent natural disasters, abnormal climate and rising sea levels. How to capture and store CO2 safely, efficiently and economically has become a research hotspot. Mineralization storage of CO2 technology has always been considered an emission reduction technology with large-scale CO2 storage potential and application prospects. Compared with traditional natural mineralized raw materials, alkaline industrial solid waste has the advantages of fast reaction rate, high carbonation efficiency, low energy consumption and low cost. Industrially produced alkaline solid waste can react with its own CO2 emissions, thereby greatly reducing its emission reduction and transportation costs.

[0003] However, there are few studies on the mineralization and storage technology of CO2 emitted from non-ferrous metal smelting. The mineralization and storage of CO2 using waste slag produced by non-ferrous smelting has broad research value. Arsenic calcium slag is a strong alkaline waste slag produced by the lime / limestone neutralization method in the process of non-ferrous metal smelting. Non-ferrous smelting enterprises widely used this process to treat arsenic-containing waste acid in the early days, thus producing a large amount of arsenic calcium slag and storing it in slag yards or tailings ponds. Arsenic calcium slag is a high-risk solid waste, the main components of which are calcium arsenate, calcium sulfate and valuable metals. It has extremely high solubility in a neutral environment. Under the action of rainwater leaching, a large amount of arsenic and heavy metals will be dissolved and released into the surrounding water and soil environment, causing serious arsenic and heavy metal pollution. This also makes the storage of arsenic calcium slag a huge waste of resources. Therefore, recovering the metal resources in arsenic calcium slag can achieve the purpose of resource reuse.

[0004] In addition, SO2 is also a major component in flue gas. SO2 emitted from industries such as thermal power generation, metal smelting, chemical manufacturing and petroleum coking accounts for more than 85% of industrial emissions. my country is rich in metal mineral resources, and a large amount of flue gas containing SO2 is produced during smelting. Therefore, SO2 emissions from the smelting industry must be strictly controlled. In recent years, the requirements for SO2 emissions have become increasingly stringent. If companies want to achieve SO2 emissions that meet standards, they must upgrade existing desulfurization processes or develop new, efficient desulfurization processes.

[0005] According to the state of the desulfurizer during the reaction, desulfurization technology can be generally divided into wet flue gas desulfurization technology, dry flue gas desulfurization technology and semi-dry flue gas desulfurization technology. Currently, the commonly used wet desulfurization technologies include limestone-gypsum method, magnesium oxide method, double alkali method, seawater desulfurization method and ammonia absorption method. The advantages of wet flue gas desulfurization technology are high SO2 removal efficiency, stable system operation, simple equipment and easy operation. However, wet flue gas desulfurization technology also has wastewater treatment problems and large initial investment and high operating costs. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method for mineralizing and sealing sulfur dioxide and carbon dioxide by using arsenic calcium slag. The method provided by the present invention can effectively mineralize and fix SO2 and CO2 gases in the form of sulfate (sulfite) or carbonate (bicarbonate) in the solid phase, and has the advantages of low raw material price and simple process.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for storing SO2 and CO2 by mineralization of arsenic-calcium slag, comprising the following steps:

[0009] mixing arsenic calcium slag and water to obtain arsenic calcium slag slurry;

[0010] The gas to be treated is mixed with the arsenic calcium slag slurry to carry out a chemical reaction, and the SO2 or CO2 is mineralized and fixed in the solid phase of the arsenic calcium slag slurry; during the chemical reaction, the pH value of the arsenic calcium slag slurry is adjusted to 2 to 13;

[0011] The gas to be treated contains SO2 and / or CO2.

[0012] Preferably, the mass fraction of arsenic in the arsenic-calcium slag is 0.1-99%.

[0013] Preferably, the concentration of arsenic-calcium slag in the arsenic-calcium slag slurry is 0.1-1000 g / L.

[0014] Preferably, the molar ratio of SO2, CO2 in the gas to be treated and calcium in the arsenic-calcium slag is (0.1-15):(0.1-13):1.

[0015] Preferably, the temperature of the chemical combination reaction is 1 to 90° C., and the time is 0.1 to 1000 h.

[0016] Preferably, the preparation of the arsenic-calcium slag comprises the following steps:

[0017] Arsenic-containing waste is neutralized with calcium oxide or calcium hydroxide to obtain arsenic-calcium slag.

[0018] Preferably, the neutralization reaction is carried out at a temperature of 1 to 90° C. and a time of 0.1 to 24 h.

[0019] The present invention provides a method for mineralizing and sealing SO2 and CO2 using arsenic calcium slag, comprising the following steps: mixing arsenic calcium slag and water to obtain arsenic calcium slag slurry; mixing the gas to be treated with the arsenic calcium slag slurry, and performing a chemical reaction to mineralize and fix SO2 or CO2 into the solid phase of the arsenic calcium slag slurry; during the chemical reaction, adjusting the pH value of the arsenic calcium slag slurry to 2 to 13; the gas to be treated contains SO2 and / or CO2. Compared with the prior art, the method provided by the present invention can effectively mineralize and fix SO2 and CO2 gases in the solid phase in the form of sulfate (sulfite) or carbonate (bicarbonate), respectively, and has the advantages of low raw material price, simple process, integrated capture and storage of SO2 and CO2, and high added utilization, and can also achieve "waste treatment with waste". BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 TEM and EDS spectra of the solid phase after SO2 is fixed in Example 1;

[0021] Figure 2 The SEM image and corresponding energy spectrum result of the solid phase after SO2 fixation after pH 13 treatment for 2 days in Example 2;

[0022] Figure 3 The XRD diagram of the solid phase at different time conditions before and after treatment at pH 7 in Example 3;

[0023] Figure 4 The solid phase XRD result of the arsenic-calcium slag slurry into which the mixed gas was first introduced in Example 4;

[0024] Figure 5 The final solid phase XRD result in the container after the mixed gas enters in Example 4;

[0025] Figure 6 This is the XRD diagram of the solid phase after SO2 was fixed in Example 5. DETAILED DESCRIPTION

[0026] The present invention provides a method for storing SO2 and CO2 by mineralization of arsenic-calcium slag, comprising the following steps:

[0027] mixing arsenic calcium slag and water to obtain arsenic calcium slag slurry;

[0028] The gas to be treated is mixed with the arsenic calcium slag slurry to carry out a chemical reaction, and the SO2 or CO2 is mineralized and fixed in the solid phase of the arsenic calcium slag slurry; during the chemical reaction, the pH value of the arsenic calcium slag slurry is adjusted to 2 to 13;

[0029] The gas to be treated contains SO2 and / or CO2.

[0030] The invention mixes arsenic calcium slag and water to obtain arsenic calcium slag slurry.

[0031] As an embodiment, the preparation of the arsenic-calcium slag comprises the following steps:

[0032] Arsenic-containing waste is neutralized with calcium oxide or calcium hydroxide to obtain arsenic-calcium slag.

[0033] As an embodiment, the arsenic-containing waste is arsenic-containing waste residue or arsenic-containing waste liquid.

[0034] As an embodiment, when the arsenic-containing waste is arsenic-containing waste slag, it also includes adding water to the reaction system; as an embodiment, the arsenic-containing waste liquid is arsenic-containing waste liquid generated in the process of non-ferrous metal smelting.

[0035] As one embodiment, the temperature of the neutralization reaction is 1 to 90°C, and the time is 0.1 to 24 hours. As another embodiment, the temperature of the neutralization reaction is 1 to 55°C, and the time is 1 to 20 hours. In a specific embodiment, the temperature of the neutralization reaction can be 10 to 55°C, and the time can be 5 to 15 hours.

[0036] As an embodiment, the mass fraction of arsenic in the arsenic-calcium slag is 0.1-99%. As another embodiment, the mass fraction of arsenic in the arsenic-calcium slag can be 1-50%. In a specific embodiment, it can be 5-20%.

[0037] In the present invention, the main elements in the arsenic calcium slag are calcium (Ca), sulfur (S), arsenic (As V In addition, the arsenic calcium slag also contains a small amount of Fe, Cu, Pb, Zn, Cd, Mg and Al and other elements. The main element composition of the arsenic calcium slag is shown in Table 1.

[0038] Table 1 Composition and content of main elements of arsenic-calcium slag

[0039]

[0040] As one embodiment, the concentration of arsenic-calcium slag in the arsenic-calcium slag slurry is 0.1-1200 g / L. As another embodiment, the concentration of arsenic-calcium slag in the arsenic-calcium slag slurry is 100-900 g / L. In a specific embodiment, the concentration of arsenic-calcium slag in the arsenic-calcium slag slurry can be 100 g / L, 200 g / L, 300 g / L, 400 g / L, 500 g / L, 600 g / L, 700 g / L, 800 g / L, or 900 g / L.

[0041] After obtaining the arsenic-calcium slag slurry, the present invention mixes the gas to be treated with the arsenic-calcium slag slurry to carry out a chemical reaction to mineralize and fix SO2 or CO2 into the solid phase of the arsenic-calcium slag slurry.

[0042] As an embodiment, during the chemical reaction, the pH value of the arsenic-calcium slag slurry is adjusted to 2-13. As an embodiment, the reagents for adjusting the pH value of the arsenic-calcium slag slurry are sulfuric acid and sodium hydroxide solution; the concentration of the sulfuric acid is 0.5 mol / L; the concentration of the sodium hydroxide solution is 0.1 mol / L.

[0043] As an embodiment, the molar ratio of SO2, CO2 and calcium in the arsenic-calcium slag in the gas to be treated is (0.1-15):(0.1-13):1. In a specific embodiment, the molar ratio of SO2, CO2 and calcium in the arsenic-calcium slag in the gas to be treated is (0.4-15):(0.5-10):1.

[0044] As an embodiment, the mixing of the gas to be treated and the arsenic-calcium slag slurry can also be replaced by first mixing the gas to be treated with water, and then mixing the resulting solution with the arsenic-calcium slag slurry.

[0045] As an embodiment, the temperature of the chemical combination reaction is 1 to 90° C., and the time is 0.1 to 1000 h. In a specific embodiment, the temperature of the chemical combination reaction can be 25 to 80° C., and the time can be 1 to 48 h.

[0046] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0047] Example 1

[0048] To 1000mL of arsenic waste liquid (As 3+ The concentration of As is 12 g / L. 5+ 1000 g of calcium oxide was added to the mixture (with a concentration of 35 g / L), and the mixture was reacted at 55° C. for 10 h. The solid was then filtered and collected to obtain arsenic calcium slag.

[0049] 40g of arsenic calcium slag and 400mL of water are mixed to obtain arsenic calcium slag slurry, wherein the arsenic content in the arsenic calcium slag is 5.86wt.%; SO2 gas is passed into the arsenic calcium slag mixed slurry under mechanical stirring, and the molar ratio of SO2 to calcium in the arsenic calcium slag is 0.7:1. After the gas is passed, the chemical reaction is continued (during the chemical reaction, 0.5mol / LH2SO4 and 0.1mol / LNaOH solution are used to always control the pH value of the chemical reaction process at 10, and the reaction temperature is 50°C), and the SO2 is mineralized and fixed to the solid phase of the arsenic calcium slag slurry to obtain a solid phase after the SO2 is fixed.

[0050] Figure 1 TEM and EDS spectra of the solid phase after SO2 is fixed in Example 1. Figure 1It can be seen that the main component of the solid phase is calcium sulfate. The changes in the total mass of the solid phase occupied by calcium sulfate before and after treatment at pH 10 are shown in Table 1.

[0051] Table 1 Changes in the total solid mass of calcium sulfate before and after treatment at pH 10

[0052] content Before treatment 1h after treatment 6h after treatment 2 days after treatment wt% 19.52 21.29 25.62 32.55

[0053] Note: Before treatment refers to the time when SO2 gas is just introduced into the arsenic-calcium slag mixture and the pH has not yet been adjusted with H2SO4 and NaOH solutions.

[0054] Example 2

[0055] 1000 g of calcium oxide was added to 1000 mL of arsenic-containing waste liquid, and the mixture was reacted at 25° C. for 24 hours. The solid was then filtered and collected to obtain arsenic-calcium slag, wherein the arsenic content in the arsenic-calcium slag was 6.9 wt.%.

[0056] 40g of arsenic calcium slag (calcium content 35.86wt.%) and 400mL of water were mixed to obtain arsenic calcium slag slurry, SO2 gas was mixed with water under mechanical stirring, and the obtained solution was dripped into the arsenic calcium slag mixed slurry, and the molar ratio of sulfur in the mixed solution of SO2 and water to calcium in the arsenic calcium slag was 15:1. After the dropwise addition was completed, the chemical reaction was continued (the pH value of the chemical reaction process was always controlled at 13 using 0.5mol / L H2SO4 and 0.1mol / LNaOH solution, and the reaction temperature was 25°C), and SO2 was mineralized and fixed to the solid phase of the arsenic calcium slag slurry to obtain a solid phase after SO2 was fixed.

[0057] Figure 2 The SEM image and corresponding spectrum results of the solid phase after SO2 fixation after pH 13 treatment for 2 days. Figure 2 (a) to (c) are SEM images of calcium sulfate at different angles; Figure 2 It can be seen that the main component of the solid phase after the reaction is calcium sulfate. The changes in the calcium sulfate content before and after treatment at pH 13 are shown in Table 2.

[0058] Table 2 Changes in the total solid mass of calcium sulfate before and after treatment at pH 13

[0059] content Before treatment 1h after treatment 6h after treatment 2 days after treatment wt% 14.09 17.23 27.55 34.37

[0060] Example 3

[0061] 600 g of calcium oxide was added to 500 mL of arsenic-containing waste liquid, and the mixture was reacted at 10° C. for 5 h. The mixture was filtered and the solid was collected to obtain arsenic-calcium slag, wherein the arsenic content in the arsenic-calcium slag was 4.25 wt.%.

[0062] Mix 100mL SO2 (purity 99%) with 400mL water, introduce oxygen for 1h to obtain sulfate solution, take 40g arsenic calcium slag, spray the sulfate solution evenly on the surface of arsenic calcium slag, the molar ratio of sulfate in the sulfate solution to calcium in the arsenic calcium slag is 0.4:1. Use 0.5mol / L H2SO4 and 0.1mol / LNaOH solution to control the pH value of the chemical reaction process at 7, and the reaction temperature is 10℃.

[0063] After stabilization for a period of time, the filtered arsenic-calcium slag was tested, and the test results were shown in Table 3: The calcium sulfate content after the chemical reaction was tested according to the method in Example 1, and the mass ratio of calcium sulfate in the solid phase on the second day of the chemical reaction was 24.82%, indicating that part of the SO2 gas was effectively fixed in the solid phase. Figure 3 The XRD diagram of the solid phase at different time conditions before and after treatment at pH 7 in this embodiment is shown in FIG. Figure 3 It can be seen that the main component of the solid phase before and after the reaction is calcium sulfate.

[0064] Table 3 Changes in the total solid mass of calcium sulfate before and after treatment at pH 7

[0065] content Before treatment 1h after treatment 6h after treatment Day 1 after treatment 2 days after treatment wt% 20.11 22.53 23.05 24.62 24.82

[0066] Example 4

[0067] 1000 g of calcium oxide was added to 800 mL of arsenic-containing waste liquid, and the mixture was reacted at 30° C. for 72 hours. The solid was filtered and collected to obtain arsenic-calcium slag, wherein the arsenic content in the arsenic-calcium slag was 4.97 wt.%.

[0068] 100g of arsenic calcium slag and 1000mL of water were mixed to obtain arsenic calcium slag slurry. CO2 and SO2 gas (the molar ratio of SO2 and CO2 was 1:1) were mixed under mechanical stirring, and then introduced into two containers connected successively with arsenic calcium slag slurry, and the molar ratio of SO2, CO2 and the total calcium in the arsenic calcium slag was 0.5:0.5:1. After the gas was introduced, the chemical reaction was continued (the pH value of the chemical reaction process was always controlled at 9 using 0.5mol / LH2SO4 and 0.1mol / LNaOH solution, and the temperature of the chemical reaction was 30°C).

[0069] Figure 4 The solid phase XRD results of the arsenic-calcium slag slurry into which the mixed gas is first introduced and the final solid phase XRD results of the container into which the mixed gas is later introduced are shown in Table 1. Figures 4-5 It can be seen that the main component of the solid phase in the arsenic-calcium slag slurry through which the mixed gas first passes is calcium sulfate ( Figure 4 The final solid phase in the container after the mixed gas enters is mainly composed of calcium carbonate sulfate ( Figure 5 ).

[0070] Example 5

[0071] 5000 g of calcium oxide was added to 2000 mL of arsenic-containing waste liquid, and the mixture was reacted at 70° C. for 720 h. The solid was filtered and collected to obtain arsenic-calcium slag, wherein the arsenic content in the arsenic-calcium slag was 6.04 wt.%.

[0072] 50g of arsenic calcium slag and 600mL of water were mixed to obtain arsenic calcium slag slurry; CO2 gas was introduced into the arsenic calcium slag mixed slurry under mechanical stirring, and the molar ratio of CO2 to calcium in the arsenic calcium slag was 0.7:1. After the gas was introduced, the chemical reaction continued, and the pH value of the chemical reaction process was always controlled at 11 using 0.5mol / L H2SO4 and 0.1mol / LNaOH solutions.

[0073] Figure 6 This is the XRD diagram of the solid phase after SO2 is fixed in Example 5. The XRD results show that the main component of the solid phase is calcium sulfate carbonate. The change in the total mass of the solid accounted for by calcium sulfate before and after the treatment at pH 11 is shown in Table 4.

[0074] Table 4 Changes in the total solid mass of calcium carbonate before and after treatment

[0075] content Before treatment 1h after treatment 6h after treatment Day 1 after treatment 2 days after treatment wt% 3.1 12.62 20.05 24.62 26.88

[0076] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for storing SO2 and CO2 by mineralization of arsenic-calcium slag, characterized in that: The following steps are involved: mixing arsenic calcium slag and water to obtain arsenic calcium slag slurry; The gas to be treated is mixed with the arsenic calcium slag slurry to carry out a chemical reaction, and the SO2 or CO2 is mineralized and fixed in the solid phase of the arsenic calcium slag slurry; during the chemical reaction, the pH value of the arsenic calcium slag slurry is adjusted to 2 to 13; The gas to be treated contains SO2 and / or CO2.

2. The method according to claim 1, characterized in that The mass fraction of arsenic in the arsenic-calcium slag is 0.1-99%.

3. The method according to claim 1, characterized in that The concentration of arsenic-calcium slag in the arsenic-calcium slag slurry is 0.1-1000 g / L.

4. The method according to claim 1, characterized in that The molar ratio of SO2, CO2 in the gas to be treated and calcium in the arsenic-calcium slag is (0.1-15):(0.1-13):

1.

5. The method according to claim 1, characterized in that The temperature of the chemical combination reaction is 1-90° C., and the time is 0.1-1000 h.

6. The method according to claim 1, characterized in that The preparation of the arsenic-calcium slag comprises the following steps: Arsenic-containing waste is neutralized with calcium oxide or calcium hydroxide to obtain arsenic-calcium slag.

7. The method according to claim 6, characterized in that The temperature of the neutralization reaction is 1-90° C. and the time is 0.1-24 hours.

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