Method for detecting fixed CO2 content in dealkalized red mud under different dealkalization treatments
Directly detecting the carbon content in dealkaline red mud through element analyzers, solving the problems of inaccurate detection results and volatile substances in the existing technology, achieving rapid and accurate detection of CO2 content in red mud, and improving the detection Intuition and accuracy.
Patent Information
- Application Number
- CN202310854964.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-12
- Publication Date
- 2025-01-14
AI Technical Summary
The existing fixed CO2 content detection method in dealkaline red mud has problems such as the Na+ concentration calculation method that cannot intuitively represent the CO2 absorption, long detection time, and the CO2 ventilation difference method can easily lead to gas leakage and inaccurate detection results. The results include dissolved and absorbed CO2 gases and volatile substances, which affect the accuracy.
The carbon content in the dealkaline red mud was directly detected by elemental analyzer. The standard curve was established by dealkaline treatment, drying, grinding and adding combustion aids to the red mud, and the content of fixed CO2 in the dealkaline red mud was calculated. The operation was simple. ,precise.
The rapid and accurate detection of CO2 content in dealkaline red mud is achieved, which avoids the defects of the existing methods, improves the intuitiveness and accuracy of the detection results, and avoids the influence of gas leakage and volatile substances.
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Figure CN119310192A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fixed CO2 content detection in red mud, and specifically relates to a method for detecting the fixed CO2 content in dealkalized red mud under different dealkalization treatments. Background Art
[0002] Red mud, as a waste residue from aluminum smelting, has the characteristics of large output and strong alkalinity. Improper treatment will have serious negative effects on the environment. The process of dealkalizing red mud with CO2 in liquid, semi-liquid or solid phase can neutralize the alkaline substances in the red mud and greatly reduce the alkalinity of the red mud. At the same time, after absorbing CO2, the red mud fixes CO2, which has economic value and can be used as a new component of "carbon sink" to achieve the goal of resource utilization of red mud with potential application value. Therefore, it is very critical to quickly and accurately detect the content of fixed CO2 in red mud after dealkalization treatment for the application of dealkalized red mud.
[0003] At present, the main methods for detecting the fixed CO2 content in dealkalized red mud are Na + There are two methods: concentration calculation method and CO2 ventilation difference method. + The calculation results of the concentration calculation method cannot directly represent the CO2 absorption amount, and there is a problem of relatively long overall detection time; the CO2 ventilation difference method has the problem of easy gas leakage in the pipeline, which affects the accuracy of the detection results. In addition, the CO2 absorption amount measured by the above two detection methods also includes the CO2 gas dissolved in the solution and other volatile substances absorbed by the red mud, so the accuracy of the detection results is low. Summary of the invention
[0004] The purpose of the present invention is to provide a method for detecting the fixed CO2 content in red mud after red mud fixes CO2 under different dealkalization treatments. By a series of treatments of the dealkalized red mud and direct detection thereof using an element analyzer, the purpose of automatic analysis of the CO2 content in the red mud is achieved. The method has the advantages of simple operation and high accuracy.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] In a first aspect, the present invention provides a method for detecting the fixed CO2 content in dealkalized red mud, comprising the following steps:
[0007] S1. De-alkali the red mud sample and dry it to obtain anhydrous de-alkali red mud;
[0008] S2, grinding the anhydrous dealkalized red mud, sieving, adding a combustion aid, and obtaining a mixed sample;
[0009] S3, establishing a standard curve, and using an element analyzer to respectively detect the carbon content in the mixed sample and the non-dealkalized red mud sample;
[0010] S4. Calculate the content of fixed CO2 in the dealkalized red mud based on the carbon content.
[0011] In step S1, the red mud is alkaline waste generated in the process of alumina production, and has a pH of 7-14, preferably 9-11.
[0012] In step S1, the dealkalization treatment is at least one of dry dealkalization, wet dealkalization or semi-dry dealkalization, preferably wet dealkalization.
[0013] The dry dealkalization process is as follows: CO2 is directly introduced into the red mud to achieve dealkalization treatment.
[0014] The conditions for dry dealkalization are: aeration volume of 5-15 mL / g·min, preferably 10 mL / g·min; aeration time of 10-120 min, such as 15 min, 30 min, 45 min, 60 min, 90 min, preferably 100-120 min; reaction temperature of 20-30°C, preferably 25°C; CO2 aeration ratio of 100%.
[0015] In step S1, the wet dealkalization is performed as follows: the red mud is sieved and mixed with water at a solid-liquid ratio of 1:(15-25) to obtain a red mud system, and CO2 is introduced into the red mud system to achieve dealkalization. The preferred solid-liquid ratio is 1:20.
[0016] The conditions for wet dealkalization are: the mesh size of the sieve is 80-100 mesh, preferably 90 mesh, the ventilation volume is 5-15 mL / g·min, preferably 10 mL / g·min; the ventilation time is 40-50 min, preferably 45 min; the reaction temperature is 50-70°C, preferably 60°C; the CO2 ventilation ratio is 1-100%, such as 5%, 7.5%, 10%, 20%, 50%, preferably 90-100%.
[0017] In step S1, the semi-dry dealkalization is carried out according to the following operation: the red mud and water are mixed in a solid-liquid ratio of 1:(0.1-0.15) to obtain a red mud system, and CO2 is introduced into the red mud system; preferably, the solid-liquid ratio is 1:0.11.
[0018] The conditions for the semi-dry dealkalization are: aeration volume of 5-15 mL / g·min, preferably 10 mL / g·min; aeration time of 40-50 min, preferably 45 min; reaction temperature of 20-60°C, such as 25°C, 30°C, 40°C, 50°C, preferably 55-60°C; CO2 aeration ratio of 100%.
[0019] In step S1, the drying conditions are: temperature of 100-240°C, preferably 105°C; time of 6-8h, preferably 7h.
[0020] In step S2, the mesh size of the sieve is 100-110 meshes.
[0021] In step S2, the combustion aid is V2O5. The amount of the combustion aid is 5-10 times the mass of the anhydrous dealkalized red mud, preferably 10 times.
[0022] In step S3, the detection parameters of the element analyzer are as follows:
[0023] Analysis mode: CHNS mode;
[0024] Left furnace temperature: no limit;
[0025] Right furnace temperature: 940-960°C, preferably 950°C;
[0026] Column temperature: 60-70°C, preferably 65°C;
[0027] Carrier gas flow rate: 130-150 ml / min, preferably 140 ml / min;
[0028] Reference gas flow: 90-110 ml / min, preferably 100 ml / min;
[0029] Helium flow rate: 240-260 ml / min, preferably 250 ml / min;
[0030] Analysis time: 650-670s, preferably 660s;
[0031] Injection delay time: 14-16s, preferably 15s;
[0032] Oxygen intake time: 4-6s, preferably 5s;
[0033] During the leak detection process, the carrier gas flow rate is required to drop below 5 ml / min within 70 seconds;
[0034] The detector level was maintained at 1000 μV.
[0035] In step S3, the formula of the standard curve is:
[0036] A=3×10 6 x+5445.9
[0037] Where: A: peak area; x: total amount of carbon in sulfonamide.
[0038] In step S4, the calculation formula is as follows:
[0039]
[0040] in:
[0041] T i : Fixed CO2 content per kilogram of red mud, g / kg;
[0042] i: sample number;
[0043] θ i : Carbon content in the ith mixed sample, %;
[0044] θ0: Carbon content in undealkalized red mud, %.
[0045] The beneficial effects achieved by the present invention are as follows:
[0046] The present invention uses an element analyzer to directly detect the fixed CO2 content in the dealkalized red mud. The detection process is simple to operate, and the detection results are more intuitive and accurate, avoiding the existing Na + The concentration calculation method cannot intuitively show the amount of CO2 absorbed and has a relatively long detection time. It also avoids the problem of gas leakage in the pipeline that easily occurs in the CO2 ventilation volume difference method, affecting the accuracy of the test results; and avoids the problem that the solution contains CO2 gas and other volatile substances absorbed by red mud, which affects the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Figure 1 The present invention provides a process flow chart of the method for detecting the content of fixed CO2 in red mud. DETAILED DESCRIPTION
[0048] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.
[0049] According to the "Element Analyzer Method for Determination of Total Carbon and Organic Matter in Soil" issued by the Ministry of Agriculture and Rural Affairs, sulfonamide was selected as the standard reagent, and its carbon content is 41.84%.
[0050] Organic element analyzer used in the following examples: FLASH 2000CHNS / O, Thermo Fisher Scientific, USA.
[0051] The red mud used in the following Examples 2-4 was sourced from Dongfang Boiler Co., Ltd. of Dongfang Electric Corporation; its water-soil ratio was 2.5:1, and its pH value was 9.94±0.02.
[0052] Example 1. Establishment of standard curve of C element content (%)
[0053] (1) Weigh approximately 0.02 mg, 0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, and 0.5 mg of the standard sample sulfonamide (CAS: 63-74-1) respectively, for a total of 6 groups, place them in a tin capsule, and accurately record the mass;
[0054] (2) Add the combustion aid V2O5 in amounts of 0.2 mg, 1 mg, 2 mg, 3 mg, 4 mg, and 5 mg, respectively, and then use tweezers to wrap the tin capsule into a square block to obtain a mixed standard sample.
[0055] (3) Using an organic element analyzer to detect the mixed standard sample, calibrate, and establish a standard curve;
[0056] The detection parameters of the organic element analyzer are as follows:
[0057] Analysis mode: CHNS mode;
[0058] Left furnace temperature: no limit;
[0059] Right furnace temperature: 950℃;
[0060] Column temperature: 65°C;
[0061] Carrier gas flow rate: 140ml / min;
[0062] Reference gas flow: 100ml / min;
[0063] Helium flow rate: 250ml / min;
[0064] Analysis time: 660s;
[0065] Injection delay time: 15s;
[0066] Oxygen intake time: 5s;
[0067] During the leak detection process, the carrier gas flow rate is required to drop below 5 ml / min within 70 seconds;
[0068] The detector level was maintained at 1000 μV.
[0069] The obtained standard curve formula is as follows:
[0070] A=3×10 6 x+5445.9
[0071] Where: A: peak area; x: total amount of carbon in sulfonamide.
[0072] Feasibility verification of the detection method provided by the present invention:
[0073] 1. Precision
[0074] A batch of wet-process dealkalized red mud was selected for precision testing, and the test results are as follows:
[0075] The carbon content of red mud after dealkalization was 0.55%, 0.59% and 0.56% with a ventilation rate of 10ml / (g·min), and the precision was 8.58%. The carbon content of red mud after dealkalization was 0.61%, 0.64% and 0.60% with a ventilation rate of 500ml / (g·min), and the precision was 8.36%. The carbon content of red mud at a reaction temperature of 60℃ was 0.69%, 0.70% and 0.66%, and the precision was 5.16%. The carbon content of red mud after the reaction at a solid-liquid ratio of 1:20 was 0.47%, 0.46% and 0.45%, and the precision was 9.87%. It can be seen that the RSD of the carbon content of red mud after dealkalization under different conditions meets the precision requirement of 10% of conventional chemical testing; at the same time, the RSD of carbon element detection of dry dealkalized red mud and semi-dry dealkalized red mud also meets the precision requirement, indicating that the method provided by the present invention is suitable for the detection of fixed carbon dioxide content in red mud obtained by different dealkalization methods.
[0076] 2. Accuracy
[0077] The 8 samples with a known carbon content of 41.84% and 20 red mud samples were tested in a random order, and the carbon contents of the 8 samples were finally detected to be 42.10%, 41.82%, 40.97%, 41.85%, 41.82%, 41.58%, 41.68% and 43.09%. It can be seen that the detection results of the sample content of the detection method are accurate, the recovery rate is 97.92%-102.99%, and the method has good accuracy.
[0078] 3. Goodness of fit R 2 =0.9997, R 2 >0.999, indicating that it has feasibility and linear relationship.
[0079] 4. The detection limit range is: the total amount of carbon in the sample is between 0.011mg-0.210mg.
[0080] Example 2: Detection of fixed CO2 content in red mud after CO2 dealkalization treatment by wet absorption
[0081] like Figure 1 As shown, the steps are as follows:
[0082] (1) Red mud dealkalization treatment:
[0083] Take an appropriate amount of red mud dried to constant weight, pass it through a 90-mesh sieve, and prepare a red mud system with a solid-liquid ratio of 1:20;
[0084] CO2 was introduced into the red mud system at a ventilation volume of 10 mL / (g·min), aeration time of 45 min, reaction temperature of 60°C, and CO2 ventilation ratio of 100% to obtain dealkalized red mud;
[0085] (2) further drying the dealkalized red mud at a temperature of 105° C. for 8 hours, wherein the moisture content of the dealkalized red mud after drying is 0%;
[0086] (3) grinding the dried dealkalized red mud;
[0087] (4) The ground dealkalized red mud is passed through a 100-mesh sieve and sealed for storage until testing.
[0088] (5) Accurately weigh 4 mg of dealkalized red mud, a total of three portions, add about 20 mg of V2O5 as a combustion aid, and wrap it in a tin capsule to serve as a test mixed sample;
[0089] (6) The carbon content in the unde-alkali red mud and the mixed sample was analyzed using a Thermo Fisher organic element analyzer (FLASH 2000CHNS / O);
[0090] (7) According to the test results of the element analyzer, the fixed CO2 content in the wet-process dealkalized red mud was calculated to be 12.22 g / kg.
[0091] Example 3: Detection of fixed CO2 content in red mud after CO2 dealkalization treatment by dry absorption
[0092] (1) Red mud dealkalization treatment:
[0093] Take an appropriate amount of red mud dried to constant weight and pass it through a 90-mesh sieve;
[0094] CO2 is introduced into the red mud for dealkalization, wherein the aeration volume is 10 mL / (g·min), the aeration time is 120 min, the reaction temperature is 25°C, the CO2 aeration ratio is 100%, and the red mud after the CO2 is introduced is the dealkalized red mud absorbing CO2;
[0095] (2) further drying the dealkalized red mud at a temperature of 105° C. for 8 hours, wherein the moisture content of the dealkalized red mud after drying is 0%;
[0096] (3) grinding the dried dealkalized red mud;
[0097] (4) The ground dealkalized red mud is passed through a 100-mesh sieve and sealed for storage until testing.
[0098] (5) Accurately weigh 4 mg of dealkalized red mud, a total of three portions, add about 20 mg of V2O5 as a combustion aid, and wrap it in a tin capsule to serve as a test mixed sample;
[0099] (6) The carbon content in the undealkalized and mixed samples was analyzed using a Thermo Fisher organic element analyzer (FLASH 2000CHNS / O);
[0100] (7) According to the test results of the element analyzer, the fixed CO2 content in the dealkalized red mud was calculated to be 5.99 g / kg.
[0101] Example 4: Detection of fixed CO2 content in red mud after CO2 dealkalization treatment by semi-dry absorption
[0102] (1) Red mud dealkalization treatment:
[0103] Take an appropriate amount of red mud dried to constant weight, pass it through a 90-mesh sieve, and prepare a red mud system with a solid-liquid ratio of 1:0.11;
[0104] CO2 was introduced into the red mud system, with an aeration volume of 10 mL / (g·min), an aeration time of 45 min, a reaction temperature of 60°C, and a CO2 aeration ratio of 100%. The red mud after the introduction of CO2 was the CO2-absorbed dealkalized red mud;
[0105] (2) further drying the dealkalized red mud at a temperature of 105° C. for 8 hours, wherein the moisture content of the dealkalized red mud after drying is 0%;
[0106] (3) grinding the dried dealkalized red mud;
[0107] (4) The ground dealkalized red mud is passed through a 100-mesh sieve and sealed for storage until testing.
[0108] (5) Accurately weigh 4 mg of red mud, a total of three portions, add about 20 mg of V2O5 as a combustion aid, and wrap it in a tin capsule to serve as a test mixed sample;
[0109] (6) The carbon content in the undealkalized and mixed samples was analyzed using a Thermo Fisher organic element analyzer (FLASH 2000CHNS / O);
[0110] (7) According to the test results of the element analyzer, the fixed CO2 content in the dealkalized red mud was calculated to be 5.99 g / kg.
[0111] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.
Claims
1. A method for detecting the fixed CO2 content in dealkalized red mud, comprising the following steps: S1. De-alkali the red mud sample and dry it to obtain anhydrous de-alkali red mud; S2, grinding the anhydrous dealkalized red mud, sieving, adding a combustion aid, and obtaining a mixed sample; S3, establishing a standard curve, and using an element analyzer to respectively detect the carbon content in the mixed sample and the non-dealkalized red mud sample; S4. Calculate the content of fixed CO2 in the dealkalized red mud based on the carbon content.
2. The method for detecting the fixed CO2 content in dealkalized red mud according to claim 1, characterized in that: In step S1, the red mud is an alkaline waste generated during the production of alumina, and has a pH of 7-14; The dealkalization is at least one of dry dealkalization, wet dealkalization or semi-dry dealkalization.
3. The method for detecting the fixed CO2 content in dealkalized red mud according to claim 2, characterized in that: In step S1, the dry dealkalization is: directly introducing CO2 into the red mud to achieve dealkalization treatment; The conditions for the dry dealkalization are: aeration volume of 5-15 mL / g·min, aeration time of 10-120 min, reaction temperature of 20-30° C., and CO2 aeration ratio of 100%.
4. The method for detecting the fixed CO2 content in dealkalized red mud according to claim 2, characterized in that: In step S1, the wet dealkalization is performed according to the following operation: the red mud is sieved and mixed with water at a solid-liquid ratio of 1:(15-25) to obtain a red mud system, and CO2 is introduced into the red mud system to achieve dealkalization treatment; The conditions for wet dealkalization are: the mesh size of the sieve is 80-100 meshes, the ventilation volume is 5-15 mL / g·min, the ventilation time is 40-50 min, the reaction temperature is 50-70° C., and the CO2 ventilation ratio is 1-100%.
5. The method for detecting the fixed CO2 content in dealkalized red mud according to claim 2, characterized in that: In step S1, the semi-dry dealkalization is performed according to the following operation: the red mud is mixed with water at a solid-liquid ratio of 1: (0.1-0.15) to obtain a red mud system, and CO2 is introduced into the red mud system; The conditions for the semi-dry dealkalization are: aeration volume of 5-15 mL / g·min, aeration time of 40-50 min, reaction temperature of 20-60° C., and CO2 aeration ratio of 100%.
6. The method for detecting the fixed CO2 content in dealkalized red mud according to any one of claims 1 to 5, characterized in that: In step S1, the drying conditions are: temperature of 100-240°C and time of 6-8h.
7. The method for detecting the fixed CO2 content in dealkalized red mud according to any one of claims 1 to 6, characterized in that: In step S2, the mesh size of the sieve is 100-110 mesh; The combustion aid is V2O5; The amount of the combustion aid used is 5-10 times the mass of the anhydrous dealkalized red mud.
8. The method for detecting the fixed CO2 content in dealkalized red mud according to any one of claims 1 to 7, characterized in that: In step S3, the detection parameters of the element analyzer are as follows: Analysis mode: CHNS mode; Right furnace temperature: 940-960℃; Column temperature: 60-70°C; Carrier gas flow rate: 130-150ml / min; Reference air flow: 90-110 ml / min; Helium flow rate: 240-260ml / min; Analysis time: 650-670s; Injection delay time: 14-16s; Oxygen intake time: 4-6s.
9. The method for detecting the fixed CO2 content in dealkalized red mud according to any one of claims 1 to 8, characterized in that: In step S3, the formula of the standard curve is: A=3×10 6 x+5445.9 in: A: peak area; x: Total amount of carbon in sulfonamide.
10. The method for detecting the fixed CO2 content in dealkalized red mud according to any one of claims 1 to 9, characterized in that: In step S4, the calculation formula is as follows: in: T i : Fixed CO2 content per kilogram of red mud, g / kg; i: sample number; θ i : Carbon content in the ith mixed sample, %; θ0: Carbon content in undealkalized red mud, %.