A method for determining nitrogen content in low-nitrogen recarburizer

Abstract

The present invention relates to the technical field of carburizers, and specifically discloses a method for determining the nitrogen content in a low-nitrogen carburizer. The carburizer is selected and crushed with a pulverizer and sieved to obtain uniform carburizer powder; a certain amount of sample is accurately weighed and put into a sample cup for standby; the treated sample is burned or decompressed to release nitrogen atoms in the carburizer from the carbon structure, thereby forming nitrogen; the generated nitrogen reacts with hydrochloric acid to generate ammonium chloride; the nitrogen in the ammonium salt is determined by a formaldehyde method, thereby obtaining the nitrogen content in the carburizer. The method of the present invention is to release nitrogen atoms in the carburizer from the carbon structure by burning or decompressing, thereby forming nitrogen, then react the nitrogen with hydrochloric acid to generate ammonium chloride, and the nitrogen in the ammonium salt is determined by a formaldehyde method, thereby obtaining the nitrogen content in the carburizer. The method is simple, and the measured nitrogen content data is accurate, the error is small, and the nitrogen release procedure is simple and easy to operate.

Description

Technical Field

[0001] The invention relates to the technical field of carburizers, in particular to a method for determining the nitrogen content in a low-nitrogen carburizer. Background Art

[0002] In the smelting process of steel products, the smelting loss of carbon elements in the molten iron is often increased due to factors such as long smelting time, insulation time, and overheating time, resulting in a decrease in the carbon content in the molten iron, which leads to the carbon content in the molten iron failing to reach the expected theoretical value of refining. The carbon-containing substances added to make up for the carbon content burned during the steel smelting process are called recarburizers. There are many kinds of raw materials for recarburizers, and the production processes are also different. There are wood carbon, coal carbon, coke, graphite, etc., and there are many small categories under each category. High-quality recarburizers generally refer to recarburizers that have been graphitized. Under high temperature conditions, the arrangement of carbon atoms is in the microscopic form of graphite, so it is called graphitization. Graphitization can reduce the content of impurities in the recarburizer, increase the carbon content of the recarburizer, and reduce the sulfur content. When used in casting, recarburizers can greatly increase the amount of scrap steel, reduce the amount of pig iron, or even eliminate pig iron. Existing recarburizers contain some impurities, mainly including ash, volatile matter, sulfur, nitrogen and moisture, and the nitrogen content in the recarburizer has a significant impact on the use effect. Recarburizers with high nitrogen content will lead to uneven recarburization, increase the risk of pore formation, and may affect the physical properties of metal materials. Therefore, it is necessary to detect the nitrogen content in the recarburizer; the existing detection method has many defects, the accuracy of the detection result is relatively low, the error is relatively large, and the nitrogen content in the recarburizer cannot be accurately obtained. Therefore, a method for determining the nitrogen content in a low-nitrogen recarburizer is provided. Summary of the invention

[0003] The purpose of the present invention is to provide a method for determining the nitrogen content in a low-nitrogen recarburizer in view of the defects of the prior art, so as to solve the problems raised by the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for determining the nitrogen content in a low-nitrogen recarburizer, the specific steps are as follows:

[0005] Step 1: Select the recarburizer, crush it with a grinder and sieve it to obtain uniform recarburizer powder; accurately weigh a certain amount of sample and put it into the sample cup for later use;

[0006] Step 2: The treated sample is burned or decompressed to release the nitrogen atoms in the recarburizer from the carbon structure, thereby forming nitrogen gas;

[0007] Step 3: reacting the generated nitrogen gas with hydrochloric acid to generate ammonium chloride;

[0008] Step 4: The nitrogen in the ammonium salt is determined by the formaldehyde method to obtain the nitrogen content in the recarburizer.

[0009] As a preferred technical solution of the present invention, the particle size of the recarburizer powder in step 1 is 100-200 microns.

[0010] As a preferred technical solution of the present invention, the specific steps of converting the nitrogen in the carburizer into nitrogen gas by heating in step 2 are as follows:

[0011] The recarburizer is placed in a heating furnace and heated to a high temperature, so that the nitrogen atoms inside it are released from the carbon structure to form nitrogen gas.

[0012] As a preferred technical solution of the present invention, the heating temperature of the heating furnace is 1800°C-2000°C.

[0014] As a preferred technical solution of the present invention, the specific steps of converting the nitrogen in the carburizer into nitrogen gas by means of reduced pressure in step 2 are as follows: the carburizer is placed in a reduced pressure boiler and the pressure of the carburizer is reduced by a reduced pressure valve or a vacuum pump, so that the boiling point of the carburizer is reduced, thereby releasing the nitrogen gas.

[0015] As a preferred technical solution of the present invention, in step 3, nitrogen reacts with hydrochloric acid to generate white smoke of ammonium chloride, which is small solid particles, and the white smoke is collected and processed.

[0016] As a preferred technical solution of the present invention, the specific steps of using the formaldehyde method to determine the nitrogen in the ammonium salt in step 4 are:

[0017] Step 4.1: Prepare the experimental solution: dissolve the ammonium salt in the strong acid to form a strong acid and weak base salt solution;

[0018] Step 4.2: Titration: Add formaldehyde solution to react with ammonium salt to generate hexamethylenetetramine;

[0019] Step 4.3: Indicator: Use phenolphthalein as an indicator to neutralize the free acid in formaldehyde;

[0020] Step 4.4: Titration endpoint: When the solution is weakly alkaline, add NaOH solution until the solution is neutral;

[0021] Step 4.5: Calculation: Calculate the nitrogen content in the ammonium salt based on the amount of NaOH consumed in the titration.

[0022] Compared with the prior art, the invention has the following beneficial effects: the method of the invention is to release nitrogen atoms in the recarburizer from the carbon structure by combustion or decompression, thereby forming nitrogen gas, and then react the nitrogen gas with hydrochloric acid to generate ammonium chloride, and adopt the formaldehyde method to measure the nitrogen in the ammonium salt, thereby obtaining the nitrogen content in the recarburizer. The method is simple, and the measured nitrogen content data is accurate with small error, and the nitrogen release procedure is simple and easy to operate. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0024] Embodiment 1: The present invention provides a technical solution: a method for determining the nitrogen content in a low-nitrogen recarburizer, the specific steps are as follows:

[0025] Step 1: Select a recarburizer and crush it with a grinder and sieve it to obtain a uniform recarburizer powder with a particle size of 100 microns; accurately weigh 100g of the sample and put it into a sample cup for later use;

[0026] Step 2: The treated sample is burned or decompressed to release the nitrogen atoms in the recarburizer from the carbon structure, thereby forming nitrogen gas;

[0027] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by heating are as follows:

[0028] The recarburizer is placed in a heating furnace and heated to 1800°C, so that the nitrogen atoms inside it are released from the carbon structure to form nitrogen gas;

[0029] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by reducing pressure are as follows: the carburizer is placed in a reduced pressure boiler and the pressure of the carburizer is reduced by a pressure reducing valve or a vacuum pump, so that the boiling point of the carburizer is reduced, thereby releasing the nitrogen gas.

[0030] Step 3: reacting the generated nitrogen gas with hydrochloric acid to generate ammonium chloride;

[0031] Step 4: Determine the nitrogen in the ammonium salt using the formaldehyde method to obtain the nitrogen content in the recarburizer;

[0032] Specific steps for determining nitrogen in ammonium salts using the formaldehyde method:

[0033] Step 4.1: Prepare the experimental solution: dissolve the ammonium salt in the strong acid to form a strong acid and weak base salt solution;

[0034] Step 4.2: Titration: Add formaldehyde solution to react with ammonium salt to generate hexamethylenetetramine;

[0035] Step 4.3: Indicator: Use phenolphthalein as an indicator to neutralize the free acid in formaldehyde;

[0036] Step 4.4: Titration endpoint: When the solution is weakly alkaline, add NaOH solution until the solution is neutral;

[0037] Step 4.5: Calculation: Calculate the nitrogen content in the ammonium salt based on the amount of NaOH consumed in the titration;

[0038] Reaction principle: Formaldehyde reacts quantitatively with ammonium salt to generate hexamethylenetetramine and hydrogen ions (H+). The hydrogen ions generated by this reaction can be titrated with NaOH standard solution, and the nitrogen content in the ammonium salt can be calculated by the amount of NaOH consumed.

[0039] Embodiment 2: The present invention provides a technical solution: a method for determining the nitrogen content in a low-nitrogen recarburizer, the specific steps are as follows:

[0040] Step 1: Select a recarburizer and crush it with a grinder and sieve it to obtain a uniform recarburizer powder with a particle size of 150 microns; accurately weigh 200g of the sample and put it into a sample cup for later use;

[0041] Step 2: The treated sample is burned or decompressed to release the nitrogen atoms in the recarburizer from the carbon structure, thereby forming nitrogen gas;

[0042] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by heating are as follows:

[0043] The recarburizer is placed in a heating furnace and heated to 1900°C, so that the nitrogen atoms inside it are released from the carbon structure to form nitrogen gas;

[0044] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by reducing pressure are as follows: the carburizer is placed in a reduced pressure boiler and the pressure of the carburizer is reduced by a pressure reducing valve or a vacuum pump, so that the boiling point of the carburizer is reduced, thereby releasing the nitrogen gas.

[0045] Step 3: reacting the generated nitrogen gas with hydrochloric acid to generate ammonium chloride;

[0046] Step 4: Determine the nitrogen in the ammonium salt using the formaldehyde method to obtain the nitrogen content in the recarburizer;

[0047] Specific steps for determining nitrogen in ammonium salts using the formaldehyde method:

[0048] Step 4.1: Prepare the experimental solution: dissolve the ammonium salt in the strong acid to form a strong acid and weak base salt solution;

[0049] Step 4.2: Titration: Add formaldehyde solution to react with ammonium salt to generate hexamethylenetetramine;

[0050] Step 4.3: Indicator: Use phenolphthalein as an indicator to neutralize the free acid in formaldehyde;

[0051] Step 4.4: Titration endpoint: When the solution is weakly alkaline, add NaOH solution until the solution is neutral;

[0052] Step 4.5: Calculation: Calculate the nitrogen content in the ammonium salt based on the amount of NaOH consumed in the titration;

[0053] Reaction principle: Formaldehyde reacts quantitatively with ammonium salt to generate hexamethylenetetramine and hydrogen ions (H+). The hydrogen ions generated by this reaction can be titrated with NaOH standard solution, and the nitrogen content in the ammonium salt can be calculated by the amount of NaOH consumed.

[0054] Embodiment 3: The present invention provides a technical solution: a method for determining the nitrogen content in a low-nitrogen recarburizer, the specific steps are as follows:

[0055] Step 1: Select a recarburizer, crush it with a grinder and sieve it to obtain a uniform recarburizer powder with a particle size of 200 microns; accurately weigh 500g of the sample and put it into a sample cup for later use;

[0056] Step 2: The treated sample is burned or decompressed to release the nitrogen atoms in the recarburizer from the carbon structure, thereby forming nitrogen gas;

[0057] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by heating are as follows:

[0058] The recarburizer is placed in a heating furnace and heated to 2000°C, so that the nitrogen atoms inside it are released from the carbon structure to form nitrogen gas;

[0059] The specific steps of converting the nitrogen in the carburizer into nitrogen gas by reducing pressure are as follows: the carburizer is placed in a reduced pressure boiler and the pressure of the carburizer is reduced by a pressure reducing valve or a vacuum pump, so that the boiling point of the carburizer is reduced, thereby releasing the nitrogen gas.

[0060] Step 3: reacting the generated nitrogen gas with hydrochloric acid to generate ammonium chloride;

[0061] Step 4: Determine the nitrogen in the ammonium salt using the formaldehyde method to obtain the nitrogen content in the recarburizer;

[0062] Specific steps for determining nitrogen in ammonium salts using the formaldehyde method:

[0063] Step 4.1: Prepare the experimental solution: dissolve the ammonium salt in the strong acid to form a strong acid and weak base salt solution;

[0064] Step 4.2: Titration: Add formaldehyde solution to react with ammonium salt to generate hexamethylenetetramine;

[0065] Step 4.3: Indicator: Use phenolphthalein as an indicator to neutralize the free acid in formaldehyde;

[0066] Step 4.4: Titration endpoint: When the solution is weakly alkaline, add NaOH solution until the solution is neutral;

[0067] Step 4.5: Calculation: Calculate the nitrogen content in the ammonium salt based on the amount of NaOH consumed in the titration;

[0068] Reaction principle: Formaldehyde reacts quantitatively with ammonium salt to generate hexamethylenetetramine and hydrogen ions (H+). The hydrogen ions generated by this reaction can be titrated with NaOH standard solution, and the nitrogen content in the ammonium salt can be calculated by the amount of NaOH consumed.

[0069] Comparative Example 1: Take 100g of the sample in Example 1, and then use the high temperature combustion-infrared absorption method: This method is based on the standard GB / T 223.69-2008, converts the nitrogen in the sample into oxides by high temperature combustion, and then determines the nitrogen content by infrared absorption method;

[0070] Comparative Example 2: Take 200 g of the sample in Example 2 and use a nitrogen analyzer or an oxygen-nitrogen analyzer to measure the nitrogen content in the graphitized carburizer sample;

[0071] Comparative Example 3: 500 g of the sample in Example 3 was taken, and the nitrogen element in the carburizer was adsorbed onto the adsorbent, and then the nitrogen element was released by heating or the like, and the nitrogen content in the sample was obtained by measuring the nitrogen element by spectroscopy;

[0072] Table 1: Nitrogen content in Examples 1-3 and Comparative Examples 1-3

[0073] Weight(g) Nitrogen weight (g) Example 1 100 4.1-4.3 Example 2 200 5.9-6.2 Example 3 500 15.1-15.5 Comparative Example 1 100 4.0-4.5 Comparative Example 2 200 5.7-6.5 Comparative Example 3 500 14.8-15.9

[0074] It can be seen from Table 1 that the nitrogen content range obtained by the method of the present invention is smaller than that of comparative documents 1-3, indicating that the data obtained by the method of the present invention is more accurate.

[0075] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A method for determining the nitrogen content in a low-nitrogen recarburizer, characterized in that: The specific steps are as follows: Step 1: Select the recarburizer, crush it with a grinder and sieve it to obtain uniform recarburizer powder; accurately weigh a certain amount of sample and put it into the sample cup for later use; Step 2: The treated sample is burned or decompressed to release the nitrogen atoms in the recarburizer from the carbon structure, thereby forming nitrogen gas; Step 3: reacting the generated nitrogen gas with hydrochloric acid to generate ammonium chloride; Step 4: The nitrogen in the ammonium salt is determined by the formaldehyde method to obtain the nitrogen content in the recarburizer.

2. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 1, characterized in that: The particle size of the recarburizer powder in step 1 is 100-200 microns.

3. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 1, characterized in that: The specific steps of converting the nitrogen in the recarburizer into nitrogen gas by heating in step 2 are as follows: the recarburizer is placed in a heating furnace and heated to a high temperature so that the nitrogen atoms inside it are released from the carbon structure to form nitrogen gas.

4. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 3, characterized in that: The heating temperature of the heating furnace is 1800°C-2000°C.

5. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 1, characterized in that: The specific steps of converting the nitrogen in the carburizer into nitrogen gas by reducing pressure in step 2 are as follows: placing the carburizer in a reduced pressure boiler and reducing the pressure of the carburizer through a pressure reducing valve or a vacuum pump to reduce the boiling point of the carburizer, thereby releasing the nitrogen gas.

6. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 1, characterized in that: In step 3, nitrogen reacts with hydrochloric acid to generate white smoke of ammonium chloride, which is small solid particles, and the white smoke is collected and processed.

7. The method for determining the nitrogen content in a low-nitrogen recarburizer according to claim 1, characterized in that: The specific steps of determining nitrogen in ammonium salt by formaldehyde method in step 4 are as follows: Step 4.1: Prepare the experimental solution: dissolve the ammonium salt in the strong acid to form a strong acid and weak base salt solution; Step 4.2: Titration: Add formaldehyde solution to react with ammonium salt to generate hexamethylenetetramine; Step 4.3: Indicator: Use phenolphthalein as an indicator to neutralize the free acid in formaldehyde; Step 4.4: Titration endpoint: When the solution is weakly alkaline, add NaOH solution until the solution is neutral; Step 4.5: Calculation: Calculate the nitrogen content in the ammonium salt based on the amount of NaOH consumed in the titration.