Resource utilization method of desulfurization waste liquid and chlorination slag

Abstract

The invention discloses a resource utilization method of desulfurization waste liquid and chlorination slag, which is characterized in that carbide slag is used as a desulfurizer for desulfurization of sulfur-containing flue gas, and the generated desulfurization waste liquid is used for treatment of the chlorination slag; chlorination slag slurry and primary filter residues are obtained after the chlorination slag is subjected to dilute acidizing, thickening and filtering, and the primary filter residues are conveyed to a power plant for power generation; the method comprises the following steps of: firstly, neutralizing chlorinated slag slurry by using desulfurization waste liquid for the first time, then, adding one or more of carbide slag, lime or caustic soda for the second time of neutralization to enable the pH value of the chlorinated slag slurry to be 7-8 to obtain neutralized slag slurry, finally, filtering the neutralized slag slurry to obtain secondary filter residues and secondary filtrate, and adding cement and gravel into the secondary filter residues to prepare concrete blocks. The secondary filtrate is sent to a sewage purification system to be treated and then reused to a dust collection slag washing procedure and a concrete block preparation procedure; the method not only scientifically treats the desulfurization waste liquid, but also realizes resource utilization of the chlorination slag, and reduces the treatment cost of the desulfurization waste liquid and the chlorination slag.

Description

Technical Field

[0001] The invention relates to the technical field of recycling industrial waste liquid and waste residue, and more specifically, to a resource utilization method of desulfurization waste liquid combined with chlorinated residue. Background Art

[0002] High-titanium slag is the raw material for the production of chloride titanium dioxide, which is prepared by smelting titanium concentrate in an electric furnace. Since titanium concentrate and auxiliary anthracite contain a small amount of sulfur, a large amount of sulfide will be produced during electric furnace smelting. The sulfur-containing tail gas is usually discharged after desulfurization treatment. The commonly used method for flue gas desulfurization in the industry is the lime-gypsum desulfurization process, and its desulfurization efficiency can reach more than 90%. However, the operating cost of using lime is relatively high, and the gypsum slurry discharged from the absorption tower must be concentrated and dehydrated to gypsum with a water content of less than 10%, which consumes a lot of energy and also has the problem of waste liquid disposal in the future.

[0003] For example, the utility model patent with the announcement number CN213680180U discloses a limestone-gypsum desulfurization wastewater chloride ion extraction system, which realizes the treatment and reuse of desulfurization wastewater. However, the removal of chloride ions through extraction and back-extraction cycles will bring about the problem of extract disposal, and the price of the extractant is relatively high, which makes the operation uneconomical. The invention patent with the announcement number CN109806767B discloses a desulfurization waste liquid treatment and reuse system, which realizes the reuse of desulfurization waste liquid. However, the number of times the desulfurization waste liquid can be reused is limited, and the desulfurization waste liquid still needs to be replaced. The problem of handling the replaced desulfurization waste liquid has not been effectively solved.

[0004] In the process of producing titanium dioxide by chloride method using high-titanium slag, most of the high-titanium slag and petroleum coke react with chlorine at high temperature to generate titanium tetrachloride, but a small amount of unreacted titanium-rich material and petroleum coke are blown out of the chlorination furnace by the gas, and then precipitated together with other metal chlorides after cooling and cyclone dust collection. After washing with dilute acid water, a chloride slag slurry is obtained, and its solid content is 5% to 10%. The chloride slag slurry is acidic, and the solids include titanium dioxide, petroleum coke, metal chlorides, etc. Lime is mainly used for neutralization and solidification at home and abroad, and then landfilled. This method produces a large amount of slag and does not make resource utilization of the chloride slag.

[0005] The proper disposal of desulfurization waste liquid and chlorination slag are the three waste problems that are a headache for the titanium dioxide industry. Solving these two types of waste can greatly promote the development of the titanium dioxide industry. However, the treatment technology of desulfurization waste liquid combined with chlorination slag has not been reported yet. Summary of the invention

[0006] In view of the above, the present invention provides a method for resource utilization of desulfurization waste liquid and chlorination slag, which not only scientifically treats the desulfurization waste liquid, but also realizes the resource utilization of chlorination slag, reducing the treatment costs of desulfurization waste liquid and chlorination slag.

[0007] The present invention provides a method for resource utilization of desulfurization waste liquid and chlorinated slag, comprising the following steps:

[0008] (1) grinding carbide slag to less than 300 meshes with a wet ball mill, with a slurry ratio of 1:3 to 1:4 and a ball loading of 20% to 30% to obtain carbide slag after ball milling, and then adding water to the milled carbide slag and stirring to obtain carbide slag slurry;

[0009] (2) pumping carbide slag slurry into a desulfurization tower to desulfurize the sulfur-containing flue gas to obtain desulfurized waste liquid;

[0010] (3) The desulfurization waste liquid is pumped from the desulfurization tower into the primary reaction tank. When the primary reaction tank is full, it overflows into the secondary reaction tank. When the secondary reaction tank is full, it overflows into the clear liquid tank. Carbide slag slurry is added to the primary reaction tank and the secondary reaction tank to maintain pH ≥ 9;

[0011] (4) slurrying the chlorinated slag with dilute acid, and thickening it with a thickener to obtain an upper clear liquid and a lower slurry, and filtering the lower slurry again to obtain a primary filtrate and a primary filter residue, and sending the upper clear liquid and the primary filtrate to a chlorinated slag slurry tank to obtain chlorinated slag slurry;

[0012] (5) sending the desulfurization waste liquid in the clear liquid tank in step (2) into the chlorinated slurry tank for the first neutralization of the chlorinated slurry to obtain the first neutralized chlorinated slurry; then adding one or more of carbide slag, lime or caustic soda to the first neutralized chlorinated slurry for the second neutralization, so that the pH of the second neutralized chlorinated slurry is 7 to 8, to obtain a neutralized slurry;

[0013] (6) The neutralized slurry is filtered to obtain secondary filter residue and secondary filtrate, cement and sand are added to the secondary filter residue to prepare concrete blocks, and the secondary filtrate is sent to the sewage purification system for treatment and then reused in the dust collection and slag washing process and the concrete block preparation process.

[0014] The concentration of carbide slag slurry is 10% to 30%.

[0015] During the desulfurization process of sulfur-containing flue gas, the pH value of the slurry in the desulfurization tower circulation pool is maintained at 6.5-9.

[0016] The main component of the primary filter residue is petroleum coke, which is used to generate electricity in power plants.

[0017] The concrete blocks are prepared according to the mass ratio of secondary filter residue: cement: sand and gravel = 20-50: 60: 120.

[0018] The beneficial effects of the present invention are:

[0019] (1) Grinding carbide slag with a ball mill increases the specific surface area of ​​carbide slag, which can increase the reaction rate of sulfide absorption after slurrying. At the same time, the fine particle size can reduce the blockage problem of slurry transportation;

[0020] (2) The slurry reaction pool of the desulfurization tower is set as three levels. The slurry from the third level clear liquid pool is sent to the chlorinated slag pool by pipeline, and the slurry at the bottom of the first and second level reaction pools is transported by pump trucks, which can make the slurry fully settle, reduce the wear and blockage of the transportation pipeline, and extend the life of the pipeline;

[0021] (3) The chlorinated slag is concentrated once and neutralized in two stages. The primary filter residue mainly contains insoluble matter such as carbon and silicon, which is sent to the power plant as fuel for power generation, greatly reducing the amount of chlorinated slag that needs to be solidified;

[0022] (4) The secondary filter residue mainly contains Fe, Mg, Al, Ca, etc. It is solidified with cement and sand to produce concrete blocks, which can be used for roadbed paving, realizing the comprehensive utilization of chlorinated residue;

[0023] (5) The present invention not only scientifically treats the desulfurization waste liquid, but also realizes the resource utilization of chlorinated slag, thereby reducing the treatment cost of the desulfurization waste liquid and chlorinated slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of a method for resource utilization of desulfurization waste liquid and chlorinated slag.

[0025] Figure 2 It is a schematic diagram of the desulfurization tower process. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in more detail below. The application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0027] Embodiment 1:

[0028] (1) 10 kg of chlor-alkali plant carbide slag (Ca(OH) 2 ≥90%) is ball-milled to less than 300 meshes with a wet ball mill, the ore-to-slurry ratio is 1:3, the ball loading amount is 30%, and the ball-milled carbide slag is obtained, and then the ball-milled carbide slag is mixed with water to obtain carbide slag slurry, and the concentration of the carbide slag slurry is 20%;

[0029] (2) Pumping carbide slag slurry into a desulfurization tower to desulfurize the sulfur-containing flue gas to obtain desulfurized waste liquid. During the desulfurization process of the sulfur-containing flue gas, SO 2 Concentration is 1000mg / m 3The sulfur-containing flue gas is heated for 10 minutes to maintain the pH value of the slurry in the desulfurization tower circulation pool at 6.5-9;

[0030] (3) The desulfurization waste liquid is pumped from the desulfurization tower into the primary reaction tank. When the primary reaction tank is full, it overflows into the secondary reaction tank. When the secondary reaction tank is full, it overflows into the clear liquid tank. Carbide slag slurry is added to the primary reaction tank and the secondary reaction tank to maintain pH ≥ 9;

[0031] (4) The chlorinated slag from the chlorinated titanium dioxide plant is slurried with dilute acid. After 10L of the chlorinated slag slurry is thickened by a thickener, an upper clear liquid and a lower slurry are obtained. The lower slurry is filtered again to obtain a primary filtrate and a primary filter residue. The upper clear liquid and the primary filtrate are sent to a chlorinated slag slurry tank to obtain chlorinated slag slurry. The main component of the primary filter residue is petroleum coke, which is used for power generation in a power plant.

[0032] (5) sending the desulfurization waste liquid in the clear liquid tank in step (2) into the chlorinated slurry tank for the first neutralization of the chlorinated slurry to obtain the chlorinated slurry after the first neutralization; then adding caustic soda to the chlorinated slurry after the first neutralization for the second neutralization, so that the pH of the chlorinated slurry after the second neutralization is 7, to obtain a neutralized slurry;

[0033] (6) Filter the neutralized slurry to obtain secondary filter residue and secondary filtrate, which are mixed in a mass ratio of secondary filter residue: cement: sand and gravel = 30:60:120, and then add 10% of water in the total amount of secondary filter residue, cement and sand and gravel to stir evenly, and after standing for ten days, obtain concrete blocks; the secondary filtrate is sent to the sewage purification system for disposal and then reused in the dust collection and washing process and the concrete block preparation process.

[0034] SO in the flue gas in Example 1 2 The concentration is stable at 25mg / m 3 , in line with national emission standards; the primary filter residue contains 35% carbon and SiO 2 25%, which can be used as fuel; the prepared concrete block has a compressive strength of 35Mpa and can be used for paving roadbed; by analyzing the whereabouts of the chlorinated slag, it can be found that the final chlorinated slag that needs to be solidified is 25%, which greatly reduces the treatment amount of chlorinated slag.

[0035] Embodiment 2:

[0036] (1) 10 kg of chlor-alkali plant carbide slag (Ca(OH) 2 ≥90%) is ball-milled to less than 300 meshes with a wet ball mill, the ore-to-slurry ratio is 1:3, the ball loading amount is 30%, and the ball-milled carbide slag is obtained, and then the ball-milled carbide slag is mixed with water to obtain carbide slag slurry, and the concentration of the carbide slag slurry is 30%;

[0037] (2) Pumping carbide slag slurry into a desulfurization tower to desulfurize the sulfur-containing flue gas to obtain desulfurized waste liquid. During the desulfurization process of the sulfur-containing flue gas, SO 2 Concentration is 1000mg / m 3 The sulfur-containing flue gas is heated for 10 minutes to maintain the pH value of the slurry in the desulfurization tower circulation pool at 6.5-9;

[0038] (3) The desulfurization waste liquid is pumped from the desulfurization tower into the primary reaction tank. When the primary reaction tank is full, it overflows into the secondary reaction tank. When the secondary reaction tank is full, it overflows into the clear liquid tank. Carbide slag slurry is added to the primary reaction tank and the secondary reaction tank to maintain pH ≥ 9;

[0039] (4) The chlorinated slag from the chlorinated titanium dioxide plant is slurried with dilute acid. After 10L of the chlorinated slag slurry is thickened by a thickener, an upper clear liquid and a lower slurry are obtained. The lower slurry is filtered again to obtain a primary filtrate and a primary filter residue. The upper clear liquid and the primary filtrate are sent to a chlorinated slag slurry tank to obtain chlorinated slag slurry. The main component of the primary filter residue is petroleum coke, which is used for power generation in a power plant.

[0040] (5) sending the desulfurization waste liquid in the clear liquid tank in step (2) into the chlorinated slurry tank for the first neutralization of the chlorinated slurry to obtain the chlorinated slurry after the first neutralization; then adding caustic soda to the chlorinated slurry after the first neutralization for the second neutralization, so that the pH of the chlorinated slurry after the second neutralization is 7, to obtain a neutralized slurry;

[0041] (6) Filter the neutralized slurry to obtain secondary filter residue and secondary filtrate, which are mixed in a mass ratio of secondary filter residue: cement: sand and gravel = 40:60:120, and then add 10% of water in the total amount of secondary filter residue, cement and sand and gravel to stir evenly, and after standing for ten days, obtain concrete blocks; the secondary filtrate is sent to the sewage purification system for disposal and then reused in the dust collection and washing process and the concrete block preparation process.

[0042] SO in the flue gas in Example 2 2 The concentration is stable at 23mg / m 3 , in line with national emission standards; the primary filter residue contains 35% carbon and SiO 2 25%, which can be used as fuel; the prepared concrete block has a compressive strength of 30Mpa and can be used for paving roadbed; by analyzing the whereabouts of the chlorinated slag, it can be found that the final chlorinated slag that needs to be solidified is 28%, which greatly reduces the treatment amount of chlorinated slag.

[0043] Embodiment 3:

[0044] (1) 10 kg of lime (CaO ≥ 90%) is ball-milled to less than 300 meshes with a wet ball mill, the ore-to-pulp ratio is 1:3, the ball loading amount is 30%, and the ball-milled carbide slag is obtained. Then, the ball-milled carbide slag is added with water and stirred evenly to obtain carbide slag slurry. The concentration of the carbide slag slurry is 20%;

[0045] (2) Pumping carbide slag slurry into a desulfurization tower to desulfurize the sulfur-containing flue gas to obtain desulfurized waste liquid. During the desulfurization process of the sulfur-containing flue gas, SO 2 Concentration is 1000mg / m 3 The sulfur-containing flue gas is heated for 10 minutes to maintain the pH value of the slurry in the desulfurization tower circulation pool at 6.5-9;

[0046] (3) The desulfurization waste liquid is pumped from the desulfurization tower into the primary reaction tank. When the primary reaction tank is full, it overflows into the secondary reaction tank. When the secondary reaction tank is full, it overflows into the clear liquid tank. Carbide slag slurry is added to the primary reaction tank and the secondary reaction tank to maintain pH ≥ 9;

[0047] (4) The chlorinated slag from the chlorinated titanium dioxide plant is slurried with dilute acid. After 10L of the chlorinated slag slurry is thickened by a thickener, an upper clear liquid and a lower slurry are obtained. The lower slurry is filtered again to obtain a primary filtrate and a primary filter residue. The upper clear liquid and the primary filtrate are sent to a chlorinated slag slurry tank to obtain chlorinated slag slurry. The main component of the primary filter residue is petroleum coke, which is used for power generation in a power plant.

[0048] (5) sending the desulfurization waste liquid in the clear liquid tank in step (2) into the chlorinated slurry tank for the first neutralization of the chlorinated slurry to obtain the chlorinated slurry after the first neutralization; then adding caustic soda to the chlorinated slurry after the first neutralization for the second neutralization, so that the pH of the chlorinated slurry after the second neutralization is 7, to obtain a neutralized slurry;

[0049] (6) Filter the neutralized slurry to obtain secondary filter residue and secondary filtrate, which are mixed in a mass ratio of secondary filter residue: cement: sand and gravel = 30:60:120, and then add 10% of water in the total amount of secondary filter residue, cement and sand and gravel to stir evenly, and after standing for ten days, obtain concrete blocks; the secondary filtrate is sent to the sewage purification system for disposal and then reused in the dust collection and washing process and the concrete block preparation process.

[0050] SO in the flue gas in Example 3 2 The concentration is stable at 15mg / m 3 , in line with national emission standards; the primary filter residue contains 35% carbon and SiO 2 25%, which can be used as fuel; the prepared concrete block has a compressive strength of 30Mpa and can be used for paving roadbed; by analyzing the whereabouts of the chlorinated slag, it can be found that the final chlorinated slag that needs to be solidified is 22%, which greatly reduces the treatment amount of chlorinated slag.

[0051] In Example 3, lime is used as a purifier to purify sulfur-containing flue gas. The purity of lime is higher than that of carbide slag, so it absorbs sulfur-containing substances in the flue gas more thoroughly, and finally discharges SO 2The concentration is lower; however, compared with lime, carbide slag has lower cost and can achieve the purpose of solid waste recycling; and because the secondary filter residue obtained by neutralizing the desulfurization waste liquid and chlorinated slurry after treating sulfur-containing flue gas with carbide slag contains a high content of SiO 2 Therefore, the resource utilization method of desulfurization waste liquid combined with chlorinated slag provided by the present invention not only scientifically treats desulfurization waste liquid, but also realizes resource utilization of chlorinated slag, reduces the treatment cost of desulfurization waste liquid and chlorinated slag, and improves the recycling rate of solid waste.

[0052] Table 1 Chlorinated slag composition % (dry basis)

[0053] Case <![CDATA[TiO 2 / %]]> C / ％ Ca / % Mg / % <![CDATA[SiO 2 / %]]> TFe / % Example 1 37.5 36.89 0.56 0.75 1.87 5.76 Example 2 38.4 37.29 0.71 0.78 2.21 6.16 Example 3 37.8 36.59 0.63 0.88 1.95 6.26

[0054] Table 2 Primary filtrate composition %

[0055] Case Fe Ca Al Mg C Example 1 7.68 0.2 1.0 0.69 0.2 Example 2 7.3 0.3 0.6 0.8 0.1 Example 3 7.4 0.3 0.5 0.72 0.2

[0056] Table 3 Secondary filter residue composition %

[0057] Case Fe Si Al Mn Ca Ti S Example 1 37.08 6.32 6.16 1.21 3.12 0.55 0.21 Example 2 36.61 6.75 7.35 2.33 2.67 1.21 0.18 Example 3 38.43 4.48 6.58 3.67 4.36 0.94 0.24

[0058] Table 4 Whereabouts of chlorinated slag

[0059] Case Chlorinated slag (dry basis) Primary filter residue (dry basis) Proportion Secondary filter residue (dry basis) Proportion Example 1 845g 635g 75％ 210g 25％ Example 2 860g 618g 72％ 242g 28％ Example 3 828g 643g 78％ 185g 22％

[0060] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for resource utilization of desulfurization waste liquid and chlorinated slag, characterized in that: The following steps are involved: (1) grinding carbide slag to less than 300 meshes with a wet ball mill, with a slurry ratio of 1:3 to 1:4 and a ball loading of 20% to 30% to obtain carbide slag after ball milling, and then adding water to the milled carbide slag and stirring to obtain carbide slag slurry; (2) pumping carbide slag slurry into a desulfurization tower to desulfurize the sulfur-containing flue gas to obtain desulfurized waste liquid; (3) The desulfurization waste liquid is pumped from the desulfurization tower into the primary reaction tank. When the primary reaction tank is full, it overflows into the secondary reaction tank. When the secondary reaction tank is full, it overflows into the clear liquid tank. Carbide slag slurry is added to the primary reaction tank and the secondary reaction tank to maintain pH ≥ 9; (4) slurrying the chlorinated slag with dilute acid, and thickening it with a thickener to obtain an upper clear liquid and a lower slurry, and filtering the lower slurry again to obtain a primary filtrate and a primary filter residue, and sending the upper clear liquid and the primary filtrate to a chlorinated slag slurry tank to obtain chlorinated slag slurry; (5) sending the desulfurization waste liquid in the clear liquid tank in step (3) into the chlorinated slurry tank for the first neutralization of the chlorinated slurry to obtain the first neutralized chlorinated slurry; Then, one or more of carbide slag, lime or caustic soda is added to the chlorinated slurry after the first neutralization to perform a second neutralization, so that the pH of the chlorinated slurry after the second neutralization is 7-8, thereby obtaining a neutralized slurry; (6) The neutralized slurry is filtered to obtain secondary filter residue and secondary filtrate, cement and sand are added to the secondary filter residue to prepare concrete blocks, and the secondary filtrate is sent to the sewage purification system for treatment and then reused in the dust collection and slag washing process and the concrete block preparation process.

2. The method for resource utilization of desulfurization waste liquid and chlorinated slag according to claim 1, characterized in that: The mass concentration of carbide slag slurry is 10% to 30%.

3. The method for resource utilization of desulfurization waste liquid and chlorinated slag according to claim 1, characterized in that: During the desulfurization process of sulfur-containing flue gas, the pH value of the slurry in the desulfurization tower circulation pool is maintained at 6.5-9.

4. The method for resource utilization of desulfurization waste liquid and chlorinated slag according to claim 1, characterized in that: The main component of the primary filter residue is petroleum coke, which is used for power generation in power plants.

5. The method for resource utilization of desulfurization waste liquid and chlorinated slag according to claim 1, characterized in that: Concrete blocks are prepared according to the mass ratio of secondary filtration residue: cement: sand and gravel = 20-50: 60: 120.

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