Phase analysis method for carbon in steelmaking sludge

Abstract

This invention belongs to the field of chemical analysis and detection technology, and discloses a phase analysis method for carbon in steelmaking sludge. The method comprises the following steps: First, three sets of samples are taken, denoted as sample A, sample B, and sample C; the carbon content of sample A is directly determined and denoted as w. 总 Sample B was subjected to acid treatment and vacuum filtration, and the carbon content of the residue was determined and recorded as w1. Sample C was first subjected to acid treatment and vacuum filtration, then organic treatment and vacuum filtration, and the carbon content of the residue was determined and recorded as w2. The total carbon content of the steelmaking sludge was finally obtained as w. 总 The free carbon content is w2, and the organic carbon content is w 有机 =w1-w2, inorganic carbon content w 无机 =w 总 -w1+w2. This invention enables comprehensive phase analysis of carbon in steelmaking sludge, accurately determining the content of various types of carbon in steelmaking sludge, thus filling the gap in carbon analysis methods for steelmaking sludge.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis and detection technology, specifically relating to a phase analysis method for carbon in steelmaking sludge. Background Technology

[0002] With increasingly stringent environmental protection requirements, the comprehensive utilization of waste resources, a strategic emerging industry, is developing rapidly. Among them, steelmaking sludge from the steel industry produces a large amount of sludge that is difficult to treat, but it also has the advantages of fine particle size and high iron content. It mainly contains iron, active lime, and various substances produced by the melting of scrap steel. Currently, its main applications are as raw materials for sintering and pelletizing, and for the deep treatment of coking wastewater.

[0003] Steelmaking sludge is characterized by its carbon content and tendency to settle, and the complex forms of carbon it exists in influence subsequent treatment methods. Therefore, comprehensive phase analysis of carbon in steelmaking sludge is necessary. Phase analysis involves the determination of phases by separating them based on differences in the physical or chemical properties of the target phase. Currently, domestic and international standards and literature mainly focus on the application processes of steelmaking sludge, with limited research on its composition. Furthermore, published data on its composition primarily focus on the determination of the main components, with no reports on phase analysis of carbon.

[0004] Total carbon (TC) in steelmaking sludge comprises organic and inorganic carbon, with inorganic carbon including free carbon and inorganic compound carbon (such as carbonates). Currently, the steel industry commonly uses the classic tubular furnace combustion volumetric method and the high-frequency induction furnace combustion infrared absorption method to determine total carbon. Free carbon is generally determined using the volumetric method following acid treatment to destroy carbonates, as described in YB / T190.6-2001 (Standard for Analysis of Protective Slag Series). However, this method has the following problems when directly applied to steelmaking sludge: the standard states that protective slag does not contain organic carbon, while steelmaking sludge does (which cannot be completely destroyed by acid treatment in the standard). General methods do not remove organic carbon during free carbon determination, resulting in a systematically higher free carbon analysis result due to the presence of organic carbon. Organic carbon is generally determined by the difference method, which requires accurate quantitative analysis of free carbon. Therefore, there is no currently available method for determining organic and free carbon in steelmaking sludge, necessitating the development of a phase analysis method for carbon in steelmaking sludge. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a phase analysis method for carbon in steelmaking sludge, which addresses the shortcomings of the existing technology. This method can perform a comprehensive phase analysis of carbon in steelmaking sludge, accurately determine the content of various types of carbon in steelmaking sludge, and fill the gap in carbon analysis methods for steelmaking sludge.

[0006] To address the technical problem proposed in this invention, this invention provides a method for phase analysis of carbon in steelmaking sludge, comprising the following steps:

[0007] 1) After drying the steelmaking sludge, take three sets of samples, which are denoted as sample A, sample B and sample C.

[0008] 2) The carbon content of sample A was determined by the combustion gas volumetric method, and the obtained carbon content was recorded as w. 总 ;

[0009] 3) Place sample B and sample C in hydrofluoric acid resistant containers respectively, add hydrochloric acid and potassium fluoride solution, heat to boiling, then filter under reduced pressure using a funnel lined with pickled asbestos, and wash the residue and pickled asbestos with hot water until neutral, then stop filtration.

[0010] 4) After the filtration of sample group B was stopped, the residue along with the acid-washed asbestos was transferred into a porcelain boat, dried, and the carbon content was determined by the combustion gas volumetric method. The carbon content obtained was recorded as w1.

[0011] 5) After stopping the filtration, the residue and acid-washed asbestos of sample group C were washed with anhydrous ethanol, and then washed with petroleum ether. Finally, the residue and acid-washed asbestos were transferred into a porcelain boat, dried, and the carbon content was determined by the combustion gas volumetric method. The carbon content obtained was recorded as w2.

[0012] 6) The final total carbon content of the steelmaking sludge is w 总 The free carbon content is w2, and the organic carbon content is w 有机 =w1-w2, inorganic carbon content w 无机 =w 总 -w1+w2.

[0013] In the above scheme, the drying temperature in step 1) is 100-110℃ and the drying time is 1-3h.

[0014] In the above scheme, the hydrofluoric acid resistant container is a tetrafluoroethylene beaker.

[0015] In the above scheme, the hydrofluoric acid resistant container and the acid-washed asbestos need to be decarbonized by high-temperature burning at 1000℃ for more than 1 hour before use, and after decarbonization, they are placed in an unoiled desiccator for later use.

[0016] In the above scheme, the concentration of hydrochloric acid is 2.4-6 mol / L, and the amount added is 0.1-1 g of sample plus 30-50 mL of hydrochloric acid.

[0017] In the above scheme, the mass concentration of the potassium fluoride solution is 5-20%, and the amount added is 0.1-1g of sample plus 2-5mL of potassium fluoride solution.

[0018] In the above scheme, the boiling time lasts for 2 to 3 minutes.

[0019] In the above scheme, the thickness of the acid-washed asbestos is 5-10 mm.

[0020] In the above scheme, after washing the residue with hot water and acid-washing the asbestos to neutrality in step 3), continue filtration for 10-30 minutes and then stop filtration to minimize the water content in the residue.

[0021] In the above scheme, the drying temperature in step 4) is 130-140℃ and the drying time is 2-3h.

[0022] In the above scheme, the process of washing the residue and acid-washed asbestos with anhydrous ethanol in step 5) is as follows: soak the residue and acid-washed asbestos with anhydrous ethanol for 5 to 10 minutes, then turn on the vacuum filter to dry, and wash in this way 3 to 4 times.

[0023] In the above scheme, the process of washing the residue and pickled asbestos with petroleum ether in step 5) is as follows: soak the residue and pickled asbestos with petroleum ether for 5 to 10 minutes, then turn on the vacuum filter to dry it. Repeat this washing process 3 to 4 times. After the last washing, continue to filter for 10 to 30 minutes and then stop the filtration to minimize the water content in the residue.

[0024] In the above scheme, the drying process in step 5) is as follows: first, heat at a low temperature of 60-80℃ for 30-60 minutes, and then dry at 130-140℃ for 1.5-2 hours.

[0025] In the above scheme, the determination of carbon content by combustion gas volumetric method is carried out in accordance with GB / T 223.69.

[0026] Furthermore, the specific process for determining the carbon content of sample A using the combustion gas volumetric method is as follows: 0.1-1g of sample and 1-2g of copper sheet are placed in a porcelain boat, which is then placed into a tube furnace ceramic tube at 1260-1280℃. The tube stopper is then tightened, and the furnace is preheated for 1.5-3 minutes. The volume of carbon dioxide produced by combustion is then determined using a carbon analyzer.

[0027] Furthermore, the specific process for determining the carbon content of the residues generated after the treatment of samples B and C using the combustion gas volumetric method is as follows: a ceramic boat containing the residues and acid-washed asbestos is placed into a ceramic tube of a tubular furnace at 1260–1280°C, the tube plug is tightened, and the furnace is preheated for 1.5–3 minutes. The volume of carbon dioxide produced by combustion is then determined using a carbon analyzer.

[0028] Furthermore, the formula for calculating carbon content is:

[0029]

[0030] In the formula:

[0031] w – Carbon content, in %;

[0032] A—At a temperature of 16℃ and a pressure of 101.3kPa, the mass (g) of carbon in one milliliter of carbon dioxide on the surface of the sealed solution, the value is taken from GB / T 223.69-2008;

[0033] V—Volume of carbon dioxide produced by combustion, in mL;

[0034] f—Temperature and pressure correction coefficients, values ​​are given in Appendix A of GB / T 223.69-2008;

[0035] m — Mass of the sample, in grams.

[0036] The technical principle of this invention is as follows:

[0037] This invention treats steelmaking sludge samples to varying degrees to determine different types of carbon content. When the sludge is directly measured using the combustion gas volumetric method without treatment, the measured carbon content is the total carbon content in the sludge. After acid treatment, the inorganic carbon in the sludge is decomposed by the acid. Subsequent vacuum filtration and acid washing of asbestos remove organic carbon and free carbon that are not decomposed by the acid; the measured carbon content in this case is the sum of the organic and free carbon contents in the sludge. When the sludge is treated with acid followed by organic solvent treatment, the inorganic carbon is decomposed by the acid while the organic carbon is dissolved by the organic solvent. Subsequent vacuum filtration and acid washing of asbestos remove only free carbon; the measured carbon content in this case is the free carbon content in the sludge. After accurately determining the free carbon content, the organic and inorganic carbon contents in the sludge can be calculated using the difference method.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1) This invention can perform comprehensive phase analysis on carbon in steelmaking sludge, accurately determine the content of various types of carbon in steelmaking sludge, and in particular solve the problem of determining free carbon in steelmaking sludge containing organic carbon, filling the gap in carbon analysis methods for steelmaking sludge.

[0040] 2) This invention utilizes the principle of "like dissolves like" to sequentially elute the organic components in the residue with anhydrous ethanol and petroleum ether. First, the water in the residue is eluted by the miscibility of anhydrous ethanol and water, avoiding the formation of water vapor due to residual water, which would lead to an overestimation of the volumetric results. Then, the anhydrous ethanol is eluted by the soluble and easily volatile properties of petroleum ether. Each step is interconnected. Finally, before the residue is dried, a low-temperature heating process is added to accelerate the volatilization of the organic solution, avoiding the risks associated with organic solvents and ensuring the safety of the experiment. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the method of the present invention. Detailed Implementation

[0042] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0043] In the following examples, the tetrafluoroethylene beaker and the acid-washed asbestos used were decarbonized by calcining at 1000°C for more than 1 hour before use, and then placed in an unoiled desiccator for later use.

[0044] Example 1

[0045] A steel plant generates a large amount of steelmaking sludge during the steelmaking process. A comprehensive phase analysis of the carbon in this sludge is required. The analysis process is as follows:

[0046] 1) After drying the steelmaking sludge at 100℃ for 3 hours, take three groups of samples with m = 0.2000g (accurate to 0.0001g) and label them as sample A, sample B and sample C.

[0047] 2) Place sample A and 1.0g of copper sheet in a porcelain boat, then place the porcelain boat into a tube furnace at 1260℃, seal the tube tightly, preheat for 1.5min, and determine the volume of carbon dioxide produced by combustion using a carbon analyzer. The volume is 7.10mL. Calculate the carbon content in sample A:

[0048]

[0049] 3) Place sample B and sample C in tetrafluoroethylene beakers respectively. Add 30 mL of 6 mol / L hydrochloric acid and 2 mL of 10% potassium fluoride solution to the tetrafluoroethylene beakers. Cover with a watch glass and heat to boiling for 2 min. Then filter under reduced pressure using a funnel lined with 6 mm thick pickled asbestos. Wash the residue and pickled asbestos with hot water until neutral. Continue filtration for 10 min and then stop filtration.

[0050] 4) After filtration of sample B was stopped, the residue, along with the acid-washed asbestos, was transferred into a ceramic boat. After drying at 130℃ for 2 hours, the ceramic boat was placed inside a tube furnace at 1260℃, the tube stopper was tightened, and preheating was performed for 1.5 minutes. The volume of carbon dioxide produced by combustion was measured to be 4.72 mL using a carbon analyzer. Calculate the carbon content of sample B after treatment:

[0051]

[0052] 5) After stopping filtration, sample C was soaked in anhydrous ethanol and acid-washed asbestos for 5 minutes, then the filtration was restarted and the sample was dried. This washing process was repeated 3 times, followed by 3 more washes with petroleum ether. After the final wash, filtration was continued for 10 minutes before stopping. Finally, the residue and acid-washed asbestos were transferred to a ceramic boat, heated at 60℃ for 30 minutes, and then dried at 130℃ for 1.5 hours. The ceramic boat was then placed in a tube furnace at 1260℃, the tube was plugged, and preheated for 1.5 minutes. The volume of carbon dioxide produced by combustion was measured to be 4.56 mL using a carbon analyzer. The carbon content of sample C after treatment was calculated.

[0053]

[0054] 6) The final total carbon content of the steelmaking sludge is w 总 =1.74%, free carbon content is w2 = 1.12%, organic carbon content is w 有机 =w1-w2=0.04%, inorganic carbon content w 无机 =w 总 -w1+w2=1.70%.

[0055] Example 2

[0056] 1) After drying the steelmaking sludge at 110℃ for 3 hours, take three groups of samples with m = 0.5000g (accurate to 0.0001g) and label them as sample A, sample B and sample C.

[0057] 2) Place sample A and 1.5g of copper sheet in a porcelain boat, then place the porcelain boat into a tube furnace at 1270℃, seal the tube tightly, preheat for 2.5min, and determine the volume of carbon dioxide produced by combustion using a carbon analyzer. The volume is 5.46mL. Calculate the carbon content in sample A:

[0058]

[0059] 3) Place sample B and sample C in a tetrafluoroethylene beaker respectively. Add 40 mL of 4 mol / L hydrochloric acid and 2 mL of 20% potassium fluoride solution to the tetrafluoroethylene beaker. Cover with a watch glass and heat to boiling for 2 min. Then filter under reduced pressure using a funnel lined with 8 mm thick pickled asbestos. Wash the residue and pickled asbestos with hot water until neutral. Continue filtration for 20 min and then stop filtration.

[0060] 4) After filtration of sample B was stopped, the residue, along with the acid-washed asbestos, was transferred into a ceramic boat. After drying at 130℃ for 2.5 hours, the ceramic boat was placed inside a tube furnace at 1270℃, the tube stopper was tightened, and preheating was performed for 2.5 minutes. A carbon analyzer determined that the volume of carbon dioxide produced during combustion was 2.95 mL. The carbon content of sample B after treatment was calculated.

[0061]

[0062] 5) After stopping filtration, sample C was soaked in anhydrous ethanol and acid-washed asbestos for 10 minutes, then the filtration was restarted and the sample was dried. This washing process was repeated 4 times, followed by 4 more washes with petroleum ether. After the final wash, filtration was continued for 15 minutes before stopping. Finally, the residue and acid-washed asbestos were transferred to a ceramic boat, heated at 70℃ for 45 minutes, and then dried at 130℃ for 2 hours. The ceramic boat was then placed in a tube furnace at 1270℃, the tube was plugged, and preheated for 2.5 minutes. The volume of carbon dioxide produced by combustion was measured to be 2.75 mL using a carbon analyzer. The carbon content of sample C after treatment was calculated.

[0063]

[0064] 6) The final total carbon content of the steelmaking sludge is w 总 =0.52%, free carbon content is w2=0.26%, organic carbon content is w 有机 =w1-w2=0.02%, inorganic carbon content w 无机 =w 总 -w1+w2=0.50%.

[0065] Example 3

[0066] 1) After drying the steelmaking sludge at 110℃ for 2 hours, take three groups of samples with m = 1.0000g (accurate to 0.0001g) and label them as sample A, sample B and sample C.

[0067] 2) Place sample A and 2g of copper sheet in a porcelain boat, then place the porcelain boat into a tube furnace at 1280℃, seal the tube tightly, preheat for 3 minutes, and determine the volume of carbon dioxide produced by combustion using a carbon analyzer. The volume is 7.22mL. Calculate the carbon content in sample A:

[0068]

[0069] 3) Place sample B and sample C in tetrafluoroethylene beakers respectively. Add 50 mL of 2.4 mol / L hydrochloric acid and 3 mL of 20% potassium fluoride solution to the tetrafluoroethylene beakers. Cover with a watch glass and heat to boiling for 3 min. Then filter under reduced pressure using a funnel lined with 10 mm thick pickled asbestos. Wash the residue and pickled asbestos with hot water until neutral. Continue filtration for 30 min and then stop filtration.

[0070] 4) After filtration of sample B was stopped, the residue along with the acid-washed asbestos was transferred into a ceramic boat. After drying at 140℃ for 2 hours, the ceramic boat was placed into a ceramic tube of a tubular furnace at 1280℃, the tube stopper was tightened, and it was preheated for 3 minutes. The volume of carbon dioxide produced by combustion was measured to be 3.30 mL using a carbon analyzer. The carbon content of sample B after treatment was calculated.

[0071]

[0072] 5) After stopping filtration, sample C was soaked in anhydrous ethanol and acid-washed asbestos for 10 minutes, then the filtration was restarted and the sample was dried. This washing process was repeated 4 times, followed by 4 more washes with petroleum ether. After the final wash, filtration was continued for 30 minutes before stopping. Finally, the residue and acid-washed asbestos were transferred to a ceramic boat, heated at 80℃ for 45 minutes, and then dried at 140℃ for 2 hours. The ceramic boat was then placed in a tube furnace at 1280℃, the tube was plugged, and preheated for 3 minutes. The volume of carbon dioxide produced by combustion was measured to be 3.10 mL using a carbon analyzer. The carbon content of sample C after treatment was calculated.

[0073]

[0074] 6) The final total carbon content of the steelmaking sludge is w 总 =0.35%, free carbon content is w2=0.15%, organic carbon content is w 有机 =w1-w2=0.01%, inorganic carbon content w 无机 =w 总 -w1+w2=0.34%.

[0075] Precision test

[0076] To verify the precision of the method of the present invention, the steelmaking sludge in Example 1 was analyzed five times. The results are shown in Table 1. As can be seen from the data in the table, the differences between the five analysis results are very small, indicating that the precision of the method of the present invention is good.

[0077] Table 1 Precision Experiment (%)

[0078]

[0079] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A phase analysis method for carbon in steelmaking sludge, characterized in that, Includes the following steps: 1) After drying the steelmaking sludge, take three sets of samples, which are labeled as sample A, sample B and sample C. 2) The carbon content of sample A was determined using the combustion gas volumetric method, and the obtained carbon content was recorded as w. 总 ; 3) Place sample B and sample C in hydrofluoric acid resistant containers respectively, add hydrochloric acid and potassium fluoride solution, heat to boiling, then filter under reduced pressure using a funnel lined with pickled asbestos, and wash the residue and pickled asbestos with hot water until neutral, then stop filtration. 4) After the filtration of sample group B was stopped, the residue along with the acid-washed asbestos was transferred into a porcelain boat, dried, and the carbon content was determined by the combustion gas volumetric method. The carbon content obtained was recorded as w1. 5) After stopping the filtration, the residue and acid-washed asbestos of sample C were washed with anhydrous ethanol 3-4 times. Each time, the residue and acid-washed asbestos were soaked in anhydrous ethanol for 5-10 minutes before filtration and drying. The residue and acid-washed asbestos were then washed with petroleum ether 3-4 times. Each time, the residue and acid-washed asbestos were soaked in petroleum ether for 5-10 minutes before filtration and drying. After the last wash, filtration was continued for 10-30 minutes. Finally, the residue and acid-washed asbestos were transferred together into a porcelain boat and heated at 60-80℃ for 30-60 minutes, and then dried at 130-140℃ for 1.5-2 hours. After drying, the carbon content was determined by the combustion gas volumetric method, and the obtained carbon content was recorded as w2. 6) The final total carbon content of the steelmaking sludge is w 总 The free carbon content is w2, and the organic carbon content is w 有机 =w1-w2, inorganic carbon content w 无机 =w 总 -w1+w2.

2. The phase analysis method for carbon in steelmaking sludge according to claim 1, characterized in that, The concentration of the hydrochloric acid is 2.4~6 mol / L, and the amount added is 0.1~1g of sample plus 30~50mL of hydrochloric acid.

3. The method for phase analysis of carbon in steelmaking sludge according to claim 1, characterized in that, The potassium fluoride solution has a mass concentration of 5-20%, and the amount added is 0.1-1g of sample plus 2-5mL of potassium fluoride solution.

4. The phase analysis method for carbon in steelmaking sludge according to claim 1, characterized in that, The drying temperature in step 1) is 100~110℃ and the drying time is 1~3h; the drying temperature in step 4) is 130~140℃ and the drying time is 2~3h.

5. The method for phase analysis of carbon in steelmaking sludge according to claim 1, characterized in that, The hydrofluoric acid resistant container is a tetrafluoroethylene beaker; the hydrofluoric acid resistant container and the acid-washed asbestos need to be decarbonized by high-temperature burning at 1000℃ for more than 1 hour before use.

6. The method for phase analysis of carbon in steelmaking sludge according to claim 1, characterized in that, The thickness of the acid-washed asbestos is 5-10 mm.

7. The method for phase analysis of carbon in steelmaking sludge according to claim 1, characterized in that, After washing the residue with hot water and acid-washing the asbestos until neutral, continue filtration for 10-30 minutes and then stop filtration.

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