阅读说明：本技术 一种铝质复合脱氧剂中氮含量的检测方法 (Method for detecting nitrogen content in aluminum composite deoxidizer ) 是由 周桂海 宋旭飞 于 2020-04-27 设计创作，主要内容包括：本发明涉及一种铝质复合脱氧剂中氮含量的检测方法,主要解决现有技术中铝质复合脱氧剂中氮含量无法检测的技术问题。本发明的技术方案为：一种铝质复合脱氧剂中氮含量的检测方法,包括以下步骤：1)制备试样,控制铝质复合脱氧剂的粒径为0.010～0.080mm；2)燃烧试样,在坩埚中分别加入0.100～0.250g的铝质复合脱氧剂试样、0.30～0.50g的锡粒和0.20～0.40g的钨粒,接着将装有试样的坩埚置于燃烧管中进行燃烧生成NO-(2)气体；3)检测试样中氮的热导电压；4)计算铝质复合脱氧剂中氮的质量含量。本发明方法具有操作简便,精密度好,准确度高。(The invention relates to a method for detecting nitrogen content in an aluminum composite deoxidizer, which mainly solves the technical problem that the nitrogen content in the aluminum composite deoxidizer in the prior art cannot be detected. The technical scheme of the invention is as follows: a method for detecting the content of nitrogen in an aluminum composite deoxidizer comprises the following steps: 1) preparing a sample, and controlling the particle size of the aluminum composite deoxidizer to be 0.010-0.080 mm; 2) burning the sample, and respectively adding 0.100-0.250 g of aluminum compound deoxidizer sample and 0.30-0 g of aluminum compound deoxidizer sample into a crucible.50g of tin particles and 0.20-0.40 g of tungsten particles, placing the crucible containing the sample in a combustion tube, and combusting to generate NO 2 A gas; 3) detecting the thermal conductivity voltage of nitrogen in the sample; 4) and calculating the mass content of nitrogen in the aluminum composite deoxidizer. The method has the advantages of simple operation, good precision and high accuracy.)

1. A method for detecting the content of nitrogen in an aluminum composite deoxidizer is characterized by comprising the following steps:

1) preparing a sample, grinding the aluminum composite deoxidizer by using a carbide grinding disc, and controlling the particle size of the aluminum composite deoxidizer to be 0.010-0.080 mm;

2) burning a sample, respectively adding 0.100-0.250 g of aluminum compound deoxidizer sample, 0.30-0.50 g of tin particles and 0.20-0.40 g of tungsten particles into a crucible, and putting the crucible containing the sample into a combustion tube for combustion to generate NO₂Controlling the temperature of the combustion tube to be 900-1050 ℃ and the combustion time to be 30-50 s, introducing oxygen and helium into the combustion tube simultaneously in the sample combustion process, wherein the oxygen flow is 1.0-1.5L/min and the helium flow is 0.8-1.3L/min, and collecting gas generated after the sample in the combustion tube is combusted;

3) detecting the thermal conductivity voltage of nitrogen in a sample, conveying gas generated after the sample is combusted to a quartz reagent tube filled with copper powder, placing the quartz reagent tube filled with copper powder in a heating furnace, controlling the temperature of the heating furnace to be 500-600 ℃, communicating the outlet of the quartz reagent tube filled with copper powder with the inlet of the quartz reagent tube filled with alkali asbestos, communicating the outlet of the quartz reagent tube filled with alkali asbestos with the inlet of the quartz reagent tube filled with magnesium perchlorate, and combusting the sampleNO in the post-generated gas₂Processing the copper powder at 500-600 ℃ to generate nitrogen; removing carbon dioxide in gas generated after the sample is combusted by alkali asbestos, and removing water in the gas generated after the sample is combusted by magnesium perchlorate; detecting the thermal conductivity voltage of nitrogen gas flowing out of the outlet of a quartz reagent tube filled with magnesium perchlorate, i.e., the thermal conductivity voltage V of nitrogen in a sample_N；

4) Calculating the mass content of nitrogen in the aluminum compound deoxidizer, calculating the mass content of nitrogen in the aluminum compound deoxidizer according to a formula I, and calculating W ═ b multiplied by V_N)×10^-3The x 100%/m formula I is shown in the specification, wherein in the formula I, W is the mass content of nitrogen in the aluminum composite deoxidizer and the unit is; m is the aluminum compound deoxidizer weighing sample amount, and the unit is g; a is the background equivalent concentration in mg; b is the conversion of the thermal conductive voltage of nitrogen to mass, and the unit is mg/mV; v_NThe unit is the heat conduction voltage of nitrogen in the aluminum composite deoxidizer, and the unit is mV; the background equivalent concentration a and the heat conduction voltage of nitrogen to mass conversion b are determined by a working curve equation of the relation between the mass of nitrogen in the nitrogen standard solution and the heat conduction voltage of nitrogen, and specifically are as follows: accurately and respectively transferring 0, 10.0, 30.0, 50.0, 70.0, 90.0 and 100.0 microliter of nitrogen standard solution with the mass concentration of 10.00mg/ml into a tin sac by using a micropipette, drying the tin sac at 85 ℃ for 3 hours, putting the tin sac into a 950 ℃ combustion tube, setting the oxygen flow to be 1.2L/min, introducing oxygen for combustion for 35 seconds, treating gas generated after the nitrogen standard solution is combusted by passing through three quartz reagent tubes respectively filled with copper powder, alkali asbestos and magnesium perchlorate in series under the action of helium with the flow of 1.0L/min, and then entering a thermal conductivity detector for detecting the thermal conductivity voltage of nitrogen; the quartz reagent tube filled with copper powder is placed in a heating furnace, the heating temperature is 550 ℃, and a second formula, a + b x V, of a unitary linear regression equation m of a working curve of the relation between the mass of nitrogen in the nitrogen standard solution and the thermal conductivity voltage of the nitrogen is calculated to determine values a and b; in the formula II, m is the mass of nitrogen in the measured nitrogen standard solution, and the unit is mg; a: background equivalent concentration in mg; b: converting the thermal conductivity voltage of nitrogen into mass, wherein the unit is mg/mV; v: the thermal conductivity voltage of nitrogen is in mV.

2. The method for detecting the nitrogen content in the aluminum composite deoxidizer of claim 1, wherein the reagents of tin particles, tungsten particles, copper powder, alkali asbestos and magnesium perchlorate are all analytical grade.

3. The method for detecting the nitrogen content in the aluminum compound deoxidizer of claim 1, wherein the particle size of the copper powder is 0.080 to 0.106 mm.

4. The method for detecting the nitrogen content in the aluminum composite deoxidizer of claim 1, wherein the quartz reagent tube is 10 to 15cm in length and 0.6 to 1.0cm in diameter.

Technical Field

The invention relates to a method for detecting components of an aluminum composite deoxidizer, in particular to a method for detecting the content of nitrogen in the aluminum composite deoxidizer, belonging to the technical field of analytical chemistry.

Background

Clean steel is a steel making production development trend. With the development of steel production, the requirements on steel smelting, casting and processing technologies are higher and higher. Especially, the steel-making production process has high requirement on the performance of the steel-making deoxidizer. The composite aluminium deoxidant is one of the most economic and efficient deoxidants for steel making, and has powerful deoxidating capacity, capacity of reducing the activity of deoxidated product in molten steel and lower residual oxygen content for complete deoxidization. The nitrogen content is one of important indexes in the aluminum compound deoxidizer, is directly related to the deoxidation effect of molten steel, and simultaneously can influence the nitrogen content fluctuation in the molten steel, so that the molten steel components do not meet the requirements, and serious economic loss is caused.

At present, the nitrogen content in a substance is generally detected by adopting a direct-reading spectroscopy method, a Kjeldahl method and a spectrophotometry method, but the methods can not be applied to the detection of the nitrogen content in the steelmaking aluminum composite deoxidizer.

The application publication No. CN109632777A discloses a method for detecting the content of ammonia nitrogen in wastewater, which mainly comprises the steps of reacting a Navier reagent with ammonia nitrogen to generate a light red complex, and detecting the content of ammonia nitrogen in water through the absorbance of the light red complex.

Chinese patent application publication No. CN105572121A discloses a method for detecting nitrogen content. The method mainly comprises the steps of digesting a sample by sulfuric acid, neutralizing redundant sulfuric acid by sodium hydroxide, adding dipropylene glycol and dimethyl sulfoxide to convert nitrogen into ammonium ions, and titrating by using a sodium hydroxide standard solution to calculate the content of nitrogen in the sample. The method is generally only suitable for detecting the nitrogen content in the agricultural fertilizer, and is complex in operation, large in amount of chemical reagents are involved, the automation degree is checked, the detection period is long, and the accuracy and precision of detection data are poor.

The application publication No. CN110308098A discloses a method for rapidly detecting the nitrogen content in P91 steel, the method measures the spectral intensity of nitrogen in a sample through a direct-reading spectrometer, and then the nitrogen content of the P91 steel is calculated by utilizing a prepared calibration curve. Although the method is simple and rapid to operate, the method is only suitable for detecting the nitrogen content in the steel metal massive sample, and meanwhile, the method has poor detection precision and accuracy and cannot meet the requirement of detecting the nitrogen content in the non-conductor powdery sample.

The related nitrogen content detection method disclosed in the prior art not only has complex operation, poor operability and long detection period, but also can not meet the requirement of detecting the nitrogen content in the aluminum composite deoxidizer.

Disclosure of Invention

The invention aims to provide a method for detecting the nitrogen content in an aluminum composite deoxidizer, which mainly solves the technical problem that the nitrogen content in the aluminum composite deoxidizer in the prior art cannot be detected.

The aluminum compound deoxidizer is an auxiliary material for a steel smelting and steelmaking process.

The technical idea of the invention is that under the condition of high-temperature oxygen introduction, nitrogen in the aluminum composite deoxidizer reacts with oxygen to generate nitrogen dioxide, the nitrogen dioxide is reduced by copper powder at a certain temperature to generate nitrogen, and then the nitrogen is decarbonized and dehydrated, and a thermal conductivity detector is used for measuring the thermal conductivity voltage of the nitrogen to calculate the mass content of the nitrogen in the aluminum composite deoxidizer.

The invention adopts the technical scheme that the method for detecting the nitrogen content in the aluminum composite deoxidizer comprises the following steps:

1) preparing a sample, grinding the aluminum composite deoxidizer by using a carbide grinding disc, and controlling the particle size of the aluminum composite deoxidizer to be 0.010-0.080 mm;

2) burning a sample, respectively adding 0.100-0.250 g of aluminum compound deoxidizer sample, 0.30-0.50 g of tin particles and 0.20-0.40 g of tungsten particles into a crucible, and putting the crucible containing the sample into a combustion tube for combustion to generate NO₂Controlling the temperature of the combustion tube to be 900-1050 ℃ and the combustion time to be 30-50 s, introducing oxygen and helium into the combustion tube simultaneously in the sample combustion process, wherein the oxygen flow is 1.0-1.5L/min and the helium flow is 0.8-1.3L/min, and collecting gas generated after the sample in the combustion tube is combusted;

3) detecting the thermal conductivity voltage of nitrogen in the sample, conveying the gas generated after the sample is combusted to a quartz reagent tube filled with copper powder, and placing the quartz reagent tube filled with copper powder in the quartz reagent tubeIn a heating furnace, controlling the temperature of the heating furnace to be 500-600 ℃, communicating an outlet of a quartz reagent tube filled with copper powder with an inlet of a quartz reagent tube filled with alkali asbestos, communicating an outlet of the quartz reagent tube filled with alkali asbestos with an inlet of a quartz reagent tube filled with magnesium perchlorate, and generating NO in gas generated after a sample is combusted₂Processing the copper powder at 500-600 ℃ to generate nitrogen; removing carbon dioxide in gas generated after the sample is combusted by alkali asbestos, and removing water in the gas generated after the sample is combusted by magnesium perchlorate; detecting the thermal conductivity voltage of nitrogen gas flowing out of the outlet of a quartz reagent tube filled with magnesium perchlorate, i.e., the thermal conductivity voltage V of nitrogen in a sample_N；

4) Calculating the mass content of nitrogen in the aluminum compound deoxidizer, calculating the mass content of nitrogen in the aluminum compound deoxidizer according to a formula I, and calculating W ═ b multiplied by V_N)×10^-3The x 100%/m formula I is shown in the specification, wherein in the formula I, W is the mass content of nitrogen in the aluminum composite deoxidizer and the unit is; m is the aluminum compound deoxidizer weighing sample amount, and the unit is g; a is the background equivalent concentration in mg; b is the conversion of the thermal conductive voltage of nitrogen to mass, and the unit is mg/mV; v_NThe unit is the heat conduction voltage of nitrogen in the aluminum composite deoxidizer, and the unit is mV; the background equivalent concentration a and the heat conduction voltage of nitrogen to mass conversion b are determined by a working curve equation of the relation between the mass of nitrogen in the nitrogen standard solution and the heat conduction voltage of nitrogen, and specifically are as follows: accurately and respectively transferring 0, 10.0, 30.0, 50.0, 70.0, 90.0 and 100.0 microliter of nitrogen standard solution with the mass concentration of 10.00mg/ml into a tin sac by using a micropipette, drying the tin sac at 85 ℃ for 3 hours, putting the tin sac into a 950 ℃ combustion tube, setting the oxygen flow to be 1.2L/min, introducing oxygen for combustion for 35 seconds, treating gas generated after the nitrogen standard solution is combusted by passing through three quartz reagent tubes respectively filled with copper powder, alkali asbestos and magnesium perchlorate in series under the action of helium with the flow of 1.0L/min, and then entering a thermal conductivity detector for detecting the thermal conductivity voltage of nitrogen; the quartz reagent tube filled with copper powder is placed in a heating furnace, the heating temperature is 550 ℃, and a second formula, a + b x V, of a unitary linear regression equation m of a working curve of the relation between the mass of nitrogen in the nitrogen standard solution and the thermal conductivity voltage of the nitrogen is calculated to determine values a and b; in the second formula, m is the substance for measuring nitrogen in the nitrogen standard solutionAmount in mg; a: background equivalent concentration in mg; b: converting the thermal conductivity voltage of nitrogen into mass, wherein the unit is mg/mV; v: the thermal conductivity voltage of nitrogen is in mV.

Furthermore, the reagents of tin particles, tungsten particles, copper powder, alkali asbestos and magnesium perchlorate are all analytically pure.

Further, the particle size of the copper powder is 0.080-0.106 mm, the length of the quartz reagent tube is 10-15 cm, and the diameter of the quartz reagent tube is 0.6-1.0 cm.

Based on the research of the applicant on the combustion behavior of the aluminum composite deoxidizer for many years, the aluminum composite deoxidizer is introduced with oxygen at 900-1050 ℃, and is added with 0.30-0.50 g of tin particles and 0.20-0.40 g of tungsten particle cosolvent, and the combustion time is 30-50 s, so that all nitrides such as aluminum nitride in a sample can be combusted and reacted to generate nitrogen dioxide.

Through research and a large number of condition tests, the applicant finds that nitrogen dioxide in gas generated by combustion can be completely reduced into nitrogen after the gas passes through copper powder at 500-600 ℃, and the nitrogen thermal conductivity voltage is detected by using a thermal conductivity detector after carbon dioxide is removed by alkali asbestos and moisture is removed by magnesium perchlorate.

Wherein the chemical equation of the reaction in the process is as follows:

compared with the prior art, the invention has the following positive effects: 1. the industrial problem that nitrogen in the aluminum composite deoxidizer cannot be detected is solved, and data support is provided for quality evaluation of the aluminum composite deoxidizer and evaluation of steelmaking deoxidization effect. 2. The method disclosed by the invention does not need complex sample pretreatment, is simple and convenient to operate, low in labor intensity and high in detection automation degree, avoids complex operation steps and has accurate and reliable detection data.

Detailed Description

The invention is further illustrated below with reference to example 1.

Embodiment 1, a method for detecting nitrogen content in an aluminum composite deoxidizer, comprising the following steps:

1) preparing a sample, grinding the aluminum composite deoxidizer by using a carbide grinding disc with the model of HSM100H, and controlling the particle size of the aluminum composite deoxidizer to be 0.010-0.080 mm;

2) burning the sample, adding 0.200g of aluminum complex deoxidizer sample, 0.40g of tin particles and 0.20g of tungsten particles into a crucible, and burning the crucible in a burning tube to produce NO₂Controlling the temperature of the combustion tube to be 1000 ℃, the combustion time to be 45s, introducing oxygen and helium into the combustion tube simultaneously in the sample combustion process, wherein the oxygen flow is 1.2L/min, the helium flow is 1.0L/min, and collecting gas generated after the sample in the combustion tube is combusted;

3) detecting the thermal conductivity voltage of nitrogen in a sample, conveying gas generated after the sample is combusted to a quartz reagent tube filled with copper powder with the particle size of 0.090mm, placing the quartz reagent tube filled with the copper powder in a heating furnace with the model of JR-1000, controlling the temperature of the heating furnace to be 550 ℃, communicating the outlet of the quartz reagent tube filled with the copper powder with the inlet of the quartz reagent tube filled with alkali asbestos, communicating the outlet of the quartz reagent tube filled with the alkali asbestos with the inlet of the quartz reagent tube filled with magnesium perchlorate, and communicating NO in the gas generated after the sample is combusted₂Processing the copper powder at 500-600 ℃ to generate nitrogen; removing carbon dioxide in gas generated after the sample is combusted by alkali asbestos, and removing water in the gas generated after the sample is combusted by magnesium perchlorate; the quartz reagent tube is 12cm in length and 0.8cm in diameter; the thermal conductivity voltage of nitrogen gas flowing out of the outlet of a quartz reagent tube filled with magnesium perchlorate, i.e., the thermal conductivity voltage V of nitrogen in a sample, was detected by a thermal conductivity detector of GC112A-TCD_N；

4) Calculating the mass content of nitrogen in the aluminum compound deoxidizer, calculating the mass content of nitrogen in the aluminum compound deoxidizer according to a formula I, and calculating W ═ b multiplied by V_N)×10^-3The x 100%/m formula I is shown in the specification, wherein in the formula I, W is the mass content of nitrogen in the aluminum composite deoxidizer and the unit is; m is the aluminum compound deoxidizer weighing sample amount, and the unit is g; a is the background equivalent concentration in mg; b is the conversion of the thermal conductive voltage of nitrogen to mass, and the unit is mg/mV; v_NThe unit is the heat conduction voltage of nitrogen in the aluminum composite deoxidizer, and the unit is mV;the background equivalent concentration a and the heat conduction voltage of nitrogen to mass conversion b are determined by a working curve equation of the relation between the mass of nitrogen in the nitrogen standard solution and the heat conduction voltage of nitrogen, and specifically are as follows: accurately and respectively transferring 0, 10.0, 30.0, 50.0, 70.0, 90.0 and 100.0 microliter of nitrogen standard solution with the mass concentration of 10.00mg/ml into a tin sac by using a micropipette, drying the tin sac at 85 ℃ for 3 hours, putting the tin sac into a 950 ℃ combustion tube, setting the oxygen flow to be 1.2L/min, introducing oxygen for combustion for 35 seconds, treating gas generated after the nitrogen standard solution is combusted by flowing through three quartz reagent tubes which are respectively filled with copper powder, alkali asbestos and magnesium perchlorate in series under the action of helium with the flow of 1.0L/min, and then entering a thermal conductivity detector to detect the thermal conductivity voltage of nitrogen; wherein the quartz reagent tube filled with copper powder is placed in a heating furnace, and the heating temperature is 550 ℃; the quartz reagent tube is 12cm in length and 0.8cm in diameter; calculating a unary linear regression equation m of a working curve of the relation between the mass of nitrogen in the nitrogen standard solution and the thermal conductivity voltage of the nitrogen, wherein the equation m is a formula II of a + b multiplied by V, and determining values a and b; in the formula II, m is the mass of nitrogen in the measured nitrogen standard solution, and the unit is mg; a: background equivalent concentration in mg; b: converting the thermal conductivity voltage of nitrogen into mass, wherein the unit is mg/mV; v: the thermal conductivity voltage of nitrogen is in mV.

The precision and accuracy of the method are confirmed by the standard addition recovery experiment and the precision experiment of the sample.

In the recovery experiment, after a nitrogen measuring standard solution is added into the aluminum composite deoxidizer, the aluminum composite deoxidizer is dried for 3 hours at the temperature of 85 ℃, the standard recovery rate of the sample is detected according to the method, and the test result is shown in table 1.

TABLE 1 sample spiking recovery test

Precision experiment, 11 times of precision experiments are carried out on nitrogen in 3 groups of aluminum composite deoxidizers, and the analysis results are shown in table 2.

TABLE 2 sample precision test

The experimental result shows that the recovery rate of the free carbon in the ironmaking blast furnace dust is 98.7-101.0%, the recovery rate is high, the detection data statistics RSD is far less than 3%, the detection data precision is good, the method is accurate and reliable, and the production requirements of iron and steel enterprises are completely met.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.