Method and device for measuring sulfur content in steel and iron substances

Abstract

The invention relates to a method and a device for determining the content of sulfur in steel substances, and the method comprises the following steps: placing a to-be-determined substance subjected to earlier stage treatment in a main reduction unit, and carrying out first reduction to obtain a first reduction gas; the first reduction gas is introduced into a secondary reduction unit, secondary reduction is conducted, second reduction gas is obtained, and the reducibility of a reducing agent in the second reduction unit is the same as that of a reducing agent in the first reduction unit; the second reducing gas is introduced into a gas washing unit to be washed, and purified sulfur-containing gas is obtained; carrying out absorption treatment on the purified sulfur-containing gas to form a solution; obtaining the absorbance of the solution; and determining the sulfur content of the to-be-detected substance based on the absorbance of the solution. And determining the sulfur content in the to-be-detected substance based on the absorbance. According to the embodiment of the invention, the sulfur-containing substance in the to-be-measured substance is reduced by adopting the two-stage reduction unit, so that the sulfur-containing substance in the to-be-measured substance is completely reduced, and the measurement precision of sulfur is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of trace element measurement, in particular to a method and a device for determining the sulfur content in steel-based materials. Background Art

[0002] Sulfur in steel can seriously affect its performance. Sulfur can have a "hot brittle" effect on the performance of steel, that is, cracks will appear in the workpiece during thermal deformation, so it is very harmful. Sulfur can also reduce the mechanical properties of steel, especially fatigue limit, plasticity and wear resistance, affecting the service life of steel parts. When the sulfur content is high, it will also cause adverse effects such as welding difficulties and reduced corrosion resistance. However, adding an appropriate amount of sulfur to certain special specifications of steel can improve machinability, processability and magnetism. Usually, the sulfur content in steel is controlled at a few ppm to several thousand ppm, or even lower, depending on its use. Therefore, the sulfur content in steel composition analysis is a must-check indicator.

[0003] At present, the main methods for determining sulfur content include titration analysis, atomic emission spectroscopy, spectrophotometry, infrared absorption spectroscopy, ion chromatography, electrochemical analysis, etc. Titration analysis has a high accuracy in constant sulfur, but a large error in trace sulfur; atomic emission spectroscopy has more interferences during determination, which need to be eliminated in advance; spectrophotometry depends to a large extent on the degree of pre-treatment of samples, and can only measure samples with a mass fraction between 0.0003% and 0.01% in reports; infrared spectroscopy, ion chromatography and electrochemical analysis methods are limited by instrument sensitivity and blank value, and because the instruments are expensive, these methods have certain limitations when determining trace sulfur. Summary of the invention

[0004] The main purpose of the present invention is to overcome the defects of the existing method for determining the sulfur content in steel-like substances and provide a new method and device for determining the sulfur content in steel-like substances. The technical problem to be solved is to achieve the separation of sulfur from the main element, eliminate the interference of the main substance and completely precipitate the sulfur-containing substance, and then perform a method for determining trace sulfur, so as to solve the problem that the determination of trace sulfur in steel-like substances depends on specific instruments and has a large influence of reagent blank, so that it is more suitable for practical use and has industrial utilization value.

[0005] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions.

[0006] Compared with the prior art, the present invention has obvious advantages and beneficial effects. From the above technical scheme, it can be seen that in order to achieve the above-mentioned invention purpose, the main technical contents of the present invention are as follows:

[0007] The present invention provides a method and device for determining the sulfur content in steel-based materials.

[0008] In one aspect, a method for determining the sulfur content in a steel-based material is provided, the method comprising:

[0009] The substance to be tested that has undergone preliminary treatment is placed in the main reduction unit for first reduction to obtain a first reducing gas;

[0010] Passing the first reducing gas into a secondary reducing unit for a second reduction to obtain a second reducing gas, wherein the reducing property of the reducing agent in the second reducing unit is the same as that of the reducing agent in the first reducing unit;

[0011] Passing the second reducing gas into a gas scrubbing unit for cleaning to obtain a purified sulfur-containing gas;

[0012] Absorbing the purified sulfur-containing gas to form a solution;

[0013] obtaining the absorbance of the solution;

[0014] The sulfur content in the substance to be tested is determined based on the absorbance of the solution.

[0015] In an optional embodiment, the reducing agent in the secondary reduction unit is a phosphoric acid-stannous phosphate mixed solution or a hydroiodic acid-hypophosphorous acid mixed solution.

[0016] In an optional embodiment, the concentration of the phosphoric acid-stannous phosphate mixed solution is prepared by adding 20g to 40g of stannous phosphate to 150mL to 350mL of phosphoric acid (ρ is 1.70g / mL) solution.

[0017] In an optional embodiment, the volume ratio of hydroiodic acid to hypophosphorous acid in the hydroiodic acid-hypophosphorous acid mixed solution is (2-8):1, wherein the mass fraction of hydroiodic acid is 57% (ρ is 1.70 g / mL), and the mass fraction of hypophosphorous acid is about 50% (ρ is 1.40 g / mL).

[0018] In an optional embodiment, the volume of the primary reduction unit is 10 mL to 50 mL, and the volume of the secondary reduction unit is 5 mL to 30 mL.

[0019] In an optional embodiment, the water used to wash the second reducing gas in the scrubbing unit is experimental water with a volume of 8 mL to 100 mL.

[0020] In an optional embodiment, the absorbent used for the absorption treatment of the purified sulfur-containing gas includes a sodium hydroxide solution, a zinc acetate solution, or a mixed solution of sodium hydroxide and zinc acetate.

[0021] On the other hand, a device for determining the sulfur content in steel-based materials is provided, the device comprising: a main reduction unit,

[0022] A secondary reduction unit connected to the gas outlet of the primary reduction unit;

[0023] A gas scrubbing unit connected to the gas outlet of the secondary reduction unit;

[0024] An absorption unit connected to the gas outlet of the scrubbing unit;

[0025] The detection unit is used to detect the liquid at the liquid outlet of the absorption unit.

[0026] In an optional embodiment, a return pipe is also included;

[0027] The main reduction unit and the secondary reduction unit are both provided with the reflux pipeline.

[0028] From the above, it can be seen that the present invention realizes the separation of sulfur from the main elements, eliminates the interference of the main substances and completely precipitates the sulfur-containing substances, and then performs a method for trace sulfur determination, so as to solve the problem that the determination of trace sulfur in steel-related substances depends on specific instruments and has a large influence of reagent blank.

[0029] By means of the above technical solution, the method and device for determining the sulfur content in steel-based materials of the present invention have at least the following advantages:

[0030] The device for determining the sulfur content in steel-related substances provided by the present invention is that after the substance to be measured is dissolved and reduced in two stages in the primary reduction unit and the secondary reduction unit, the sulfur-containing substance is purged out of the reduction unit by an inert gas in the form of hydrogen sulfide, and is absorbed in the absorption unit after being cleaned by the gas washing unit. Subsequently, color development is performed with a colorimetric determination to calculate the trace sulfur content in the substance to be measured. Based on the embodiment of the present invention, a two-stage reduction unit (primary reduction unit and secondary reduction unit) is used to oxidize and reduce the sulfur in the substance to be measured to ensure that the sulfur in the substance to be measured is completely reduced, thereby improving the measurement accuracy of sulfur.

[0031] In summary, the special method and device for determining sulfur content in steel-like substances of the present invention realizes the separation of sulfur from the main element, eliminates the interference of the main substance and completely precipitates the sulfur-containing substance, and then performs the method for determining trace sulfur, so as to solve the problem that the determination of trace sulfur in steel-like substances depends on specific instruments and has a large influence of reagent blank, so that it is more suitable for practical use and has industrial utilization value. It has the above-mentioned advantages and practical value, and there is no similar design published or used in the method and device for determining sulfur content in similar steel-like substances, so it is indeed innovative. It has great improvements in both the method and device for determining sulfur content in steel-like substances and in function, and has great progress in technology, and has produced a good and practical effect. It has multiple functions improved compared with the existing method and device for determining sulfur content in steel-like substances, so it is more suitable for practical use and has wide industrial utilization value. It is truly a novel, progressive and practical new design.

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0033] The specific method and device for determining the sulfur content in steel-based materials of the present invention are described in detail in the following examples and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic flow chart of a method for determining sulfur content in steel-based materials provided in an embodiment of the present invention.

[0035] Figure 2 A simplified schematic diagram of a device for determining sulfur content in steel-based materials provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method of the method for determining the sulfur content in steel-like materials proposed by the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0037] In order to solve the problem of determining trace sulfur in steel-like substances, the present invention provides a method for determining the sulfur content in steel-like substances, realizes the separation of sulfur from the main element, and then performs a method for determining trace sulfur. Experiments have proved that the device has good reduction efficiency. The interference of the main substance can be eliminated and the sulfur-containing substance can be completely precipitated. The mass fraction of sulfur measured is in the range of 0.0003% to 0.10%, which is an efficient and practical method.

[0038] See also Figure 1As shown, the method for determining the sulfur content in steel-based materials according to a preferred embodiment of the present invention mainly comprises the following steps:

[0039] In one aspect, a method for determining the sulfur content in a steel-based material is provided, the method comprising:

[0040] Step S101, placing the pre-treated substance to be tested in a main reduction unit, performing a first reduction, and obtaining a first reducing gas.

[0041] Step S102, passing the first reducing gas into a secondary reduction unit for a second reduction to obtain a second reducing gas, wherein the reducing property of the reducing agent in the second reduction unit is the same as that of the reducing agent in the first reduction unit.

[0042] Step S103, passing the second reducing gas into a gas washing unit for washing to obtain purified sulfur-containing gas.

[0043] Step S104: Absorbing the purified sulfur-containing gas to form a solution.

[0044] Step S105, obtaining the absorbance of the solution.

[0045] Step S106: Determine the sulfur content in the substance to be tested based on the absorbance of the solution.

[0046] The method and device for determining the sulfur content in steel-based materials of the present invention have at least the following advantages:

[0047] The device for measuring sulfur content in steel-related substances provided by the present invention is that after the substance to be tested is dissolved and reduced in two stages in the primary reduction unit and the secondary reduction unit, the sulfur-containing substance is purged out of the reduction unit by an inert gas in the form of hydrogen sulfide, and is absorbed in the absorption unit after passing through the gas washing unit. Subsequently, color development is performed with a colorimetric determination to calculate the trace sulfur content in the substance to be tested. Based on the embodiment of the present invention, a two-stage reduction unit (primary reduction unit and secondary reduction unit) is used to oxidize and reduce the sulfur in the substance to be tested to ensure that the sulfur in the substance to be tested is completely reduced, thereby improving the measurement accuracy of sulfur.

[0048] In the embodiment of the present invention, a color developer is added to the solution after the absorption treatment for subsequent colorimetric determination, and the mass fraction of sulfur in the substance to be measured is calculated by the absorbance value of the obtained solution. The mass fraction of sulfur measured is in the range of 0.0003% to 0.10%.

[0049] In the embodiment of the present invention, the primary reduction unit can be a primary reduction gas cylinder, that is, a gas cylinder that can be used to hold liquid. The secondary reduction unit can be a secondary reduction gas cylinder, that is, a gas cylinder that can be used to hold liquid. The embodiment of the present invention is not limited to the form of the primary reduction gas cylinder and the secondary reduction gas cylinder.

[0050] In an optional embodiment, the reducing agent in the secondary reduction unit is a phosphoric acid-stannous phosphate mixed solution or a hydroiodic acid-hypophosphorous acid mixed solution.

[0051] In an optional embodiment, the concentration of the phosphoric acid-stannous phosphate mixed solution is prepared by adding 20 g to 40 g of stannous phosphate to 150 mL to 350 mL of phosphoric acid (ρ is 1.70 g / mL) solution.

[0052] The volume ratio of hydroiodic acid to hypophosphorous acid in the hydroiodic acid-hypophosphorous acid mixed solution is (2-8):1, illustratively, it can be 2:1, 2.8:1, 3:1, 3.2:1, 3.3:1, 4:1, 4.8:1, 4.9:1, 4.5:1, 5:1, 5.2:1, 5.3:1, 6.5:1, 7.8:1, 7.9:1 or 8:1, etc. Among them, the mass fraction of hydroiodic acid is 57% (ρ is 1.70 g / mL), and the mass fraction of hypophosphorous acid is about 50% (ρ is 1.40 g / mL).

[0053] In the hydroiodic acid-hypophosphorous acid mixed solution, the hypophosphorous acid solution can be prepared by glacial acetic acid and sodium hypophosphite, wherein the volume ratio of hydroiodic acid to glacial acetic acid is (3-5):1, illustratively, it can be 3:1, 3.2:1, 3.3:1, 4:1, 4.8:1, 4.9:1, 4.5:1, 5:1. The mass fraction of hydroiodic acid is 25% (ρ is 1.50 g / mL), wherein the system concentration of hydroiodic acid-hypophosphorous acid prepared by glacial acetic acid and sodium hypophosphite is 40 g to 70 g of sodium hypophosphite added to 350 mL to 500 mL of solution.

[0054] In an optional embodiment, the volume of the primary reduction unit is 10 mL to 50 mL, and the volume of the secondary reduction unit is 5 mL to 30 mL.

[0055] Exemplarily, the volume of the primary reduction unit can be 10 mL, 15 mL, 16 mL, 19 mL, 20 mL, 25 mL, 35 mL, 45 mL, 50 mL, etc. The volume of the secondary reduction unit can be 5 mL, 6 L, 7 mL, 10 mL, 15 mL, 16 mL, 19 mL, 20 mL, 25 mL, etc.

[0056] In an optional embodiment, the water used to wash the second reducing gas in the scrubbing unit is experimental water, and the volume is 8 mL to 100 mL. For example, the volume of the experimental water can be 8 mL, 10 mL, 15 mL, 16 mL, 19 mL, 20 mL, 25 mL, 35 mL, 45 mL, 50 mL, 60 mL, 65 mL, 75 mL, 85 mL or 100 mL, etc.

[0057] In an optional embodiment, the absorbent used for the absorption treatment of the purified sulfur-containing gas includes a sodium hydroxide solution, a zinc acetate solution, or a mixed solution of sodium hydroxide and zinc acetate.

[0058] On the other hand, a device for determining the sulfur content in a steel-based material is provided, the device comprising: a primary reduction unit, a secondary reduction unit connected to a gas outlet of the primary reduction unit;

[0059] A gas scrubbing unit connected to the gas outlet of the secondary reduction unit;

[0060] An absorption unit connected to the gas outlet of the scrubbing unit;

[0061] The detection unit is used to detect the liquid at the liquid outlet of the absorption unit.

[0062] In an optional embodiment, a return pipe is also included; both the primary reduction unit and the secondary reduction unit are provided with a return pipe.

[0063] In an optional embodiment, a reflux condenser is further included, and the reflux condenser is connected to the reflux pipe. In an optional embodiment, a heating furnace is further included, and the main reduction unit and the secondary reduction unit are heated by the heating furnace.

[0064] In the embodiment of the present invention, each component is connected in sequence through a glass conduit and a flexible tube. When air is introduced into the main reduction bottle (main reduction unit), the pipeline extends into the bottom of the main reduction bottle to mix the solution evenly and discharge the air in the measuring device. The solution in the main reduction bottle refluxes to the main reduction bottle through the reflux condenser. Similarly, the solution in the secondary reduction bottle refluxes to the secondary reduction bottle (secondary reduction unit) through the reflux condenser.

[0065] It should be noted that in the embodiment of the present invention, the gas introduced into the primary reduction unit and the secondary reduction unit is an inert gas such as nitrogen or helium, which does not react with the solution in the bottle. The gas flow rate ranges from 20 mL / min to 150 mL / min. Exemplarily, the absorption bottle is a 20 mL or 100 mL volumetric bottle.

[0066] Furthermore, in the embodiment of the present invention, the main reduction bottle and the secondary reduction bottle are made of glass or ceramic that does not react with the reduction solvent. Each unit (main reduction unit, secondary reduction unit, gas washing unit and absorption unit) is sealed and connected.

[0067] Furthermore, the absorption bottle is designed to be open, so that excess purge gas can be discharged.

[0068] Furthermore, after the sulfur-containing substance is completely absorbed by the absorption liquid in the form of hydrogen sulfide, the absorption bottle is removed and a color developer is added. After color development is completed, its absorbance is measured at 680nm on a spectrophotometer. After subtracting the absorbance of the accompanying sample blank, the corresponding sulfur content is found from the working curve or calculated using a regression equation. The sulfur mass fraction in the substance to be tested is calculated using the following formula: sulfur mass fraction Where m1: the corresponding sulfur content found from the working curve or calculated using the regression equation, in g; m: the mass of the substance to be tested, in g.

[0069] Furthermore, in the embodiment of the present invention, the determination of the sulfur content in the steel-related material can be obtained by the above method, that is, by using spectrophotometry, after the sulfur-containing material is completely absorbed by the absorption liquid in the form of hydrogen sulfide to form a solution, a color developer is added to the solution, and after color development is completed, its absorbance is measured on a spectrophotometer. After the absorbance of the blank sample is subtracted from the measured absorbance, the corresponding sulfur content in the solution is obtained from the working curve or calculated using a regression equation.

[0070] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0071] Example:

[0072] The following examples are used to determine the trace sulfur content of steel materials. Figure 2 , mainly including ventilation pipeline 1, flow meter 2, primary reduction bottle 3, secondary reduction bottle 4, condenser 5, condenser 6, heater 7, heater 8, gas washing bottle 9, absorption bottle 10. The above-mentioned related components are connected in sequence through glass conduits and flexible tubes, and also include pistons and other parts well known in the art.

[0073] The determination method of the embodiment: after the substance to be tested has been pre-treated, a portion of the solution is transferred or taken to the main reduction bottle, a reduction solvent is added to the main reduction bottle 3 and the secondary reduction bottle 4 containing the sample, a certain volume of water is added to the washing bottle 9, and an absorption solution is added to the absorption bottle 10. The pipeline is connected, and an inert gas is introduced through a gas flow meter and purged for 1min to 10min. Then, the heating device is turned on to make the solution in the reduction bottle quickly reach a specified temperature. After maintaining it for a certain period of time, the heating device is turned off, the absorption bottle is removed, the bottle mouth is rinsed with water, and the required reagents are added to perform colorimetric determination, thereby calculating the mass fraction of trace sulfur in the substance to be tested.

[0074] Embodiment 1:

[0075] 1. This example is an analysis process of trace sulfur content in pig iron. 1.0248g of sample is weighed at

[0076] In a 400mL tall beaker, add 10mL of a hydrochloric acid-nitric acid mixture [1 volume of hydrochloric acid (ρ is about 1.19 g / mL) and 1 volume of nitric acid (ρ is about 1.40 g / mL)], place at room temperature for 30 minutes, and slowly heat until the dissolution reaction stops. Add 5.0mL of perchloric acid, heat until white smoke appears, and cool slightly. Add 5.0mL of hydrochloric acid (ρ is about 1.19 g / mL), continue heating until there is no white smoke from perchloric acid and the solution is dry. After cooling, add 10mL of hydrochloric acid solution [1 volume of hydrochloric acid (ρ is about 1.19 g / mL) and 1 volume of water], heat to dissolve the dried salts, cool to room temperature, and transfer the solution to the main reduction bottle (the main reduction unit of the present invention). 20 mL and 5 mL of reducing solvent: phosphoric acid-stannous phosphate solution (20 g of stannous phosphate was added to 150 mL of phosphoric acid solution (ρ was 1.70 g / mL)) were added to the main reduction bottle and the secondary reduction bottle (secondary reduction unit of the present invention), 10 mL of water was added to the washing bottle (washing unit of the present invention), 8 mL of sodium hydroxide (1.2 mol / L) absorption liquid was added to the 20 mL absorption bottle (absorption unit of the present invention), pipelines were connected, cooling water was passed, and the nitrogen flow rate was controlled to 100 mL / min. After passing nitrogen for 5 minutes, the secondary reduction bottle was first heated. When the solution reached a slight boiling state, the main reduction bottle was heated to keep the solution in a slight boiling state for 30 minutes. After distillation was completed, the absorption bottle was removed, and 5 mL of N,N-dimethyl-p-phenylenediamine hydrochloride (1g / L), cover the bottle stopper, shake gently, open the bottle stopper, immediately add 0.5mL ferric chloride hydrochloric acid solution (15g / L), add 1mL hydrochloric acid (ρ is about 1.19g / mL), cover the bottle stopper, rinse the absorption bottle wall with water, shake well, let it stand for 15min, dilute with water to the scale, and shake well again. At 680nm on a spectrophotometer, use a 2cm colorimetric dish to measure its absorbance with air or water as a reference. After subtracting the absorbance of the blank prepared with the sample, the sample absorbance is 0.218. From the working curve measured by the above system using the standard solution prepared with potassium sulfate, the corresponding sulfur content is 3.24μg. According to the formula The calculated sulfur content in the sample is 0.0003%. In the formula, m1: sulfur content in the sample found from the working curve, μg; m: sample mass, g.

[0077] Embodiment 2:

[0078] This embodiment is an analysis process of trace sulfur content in carbon steel. Weigh 0.5200g of sample into a 400mL tall beaker, add 10mL of hydrochloric acid-nitric acid mixture [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of nitric acid (ρ is about 1.40g / mL)], leave at room temperature for 30 minutes, and slowly heat until the dissolution reaction stops. Add 5.0mL of perchloric acid, heat until white smoke appears, and cool slightly. Add 5.0mL of hydrochloric acid (ρ is about 1.19g / mL), continue heating until there is no white smoke from perchloric acid and the solution is dry. After cooling, add 10mL of hydrochloric acid [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of water, heat to dissolve the dried salts, cool to room temperature, and transfer the solution to the main reduction bottle. Add 30mL and 10mL of reducing solvent into the main reduction bottle and the secondary reduction bottle respectively: hydroiodic acid-hypophosphorous acid solution (add 50mL hypophosphorous acid (ρ is about 1.40g / mL) into 200mL hydroiodic acid (ρ is about 1.70g / mL)), add 10mL of water into the wash bottle, add 50mL of sodium hydroxide (1.0mol / L) absorption liquid into the 100mL absorption bottle, connect the pipeline, pass cooling water, control the nitrogen flow rate to 100mL / min, pass nitrogen for 5min, first heat the secondary reduction bottle, when the solution reaches a slight boil, heat the main reduction bottle, keep the solution in a slight boiling state for 30min, after distillation is completed, remove the absorption bottle, add 10mL N,N-dimethyl-p-phenylenediamine hydrochloride (2g / L), cover the bottle stopper, shake gently, open the bottle stopper, immediately add 1.0mL ferric chloride hydrochloric acid solution (20g / L), add 1mL hydrochloric acid (ρ is about 1.19g / mL), cover the bottle stopper, rinse the absorption bottle wall with water, shake well, let it stand for 15min, dilute with water to the scale, and shake well again. At 680nm on a spectrophotometer, use a 2cm colorimetric dish to measure its absorbance with air or water as a reference. After subtracting the absorbance of the blank prepared with the sample, the sample absorbance is 0.148. From the working curve measured by the above system using the standard solution prepared with potassium sulfate, the corresponding sulfur content is 8.08μg. According to the formula The calculated sulfur content in the sample is 0.0016%. In the formula, m1: sulfur content in the sample found from the working curve, μg; m: sample mass, g.

[0079] Embodiment 3:

[0080] This embodiment is an analysis process of trace sulfur content in alloy steel. Weigh 0.5000g of sample in a 400mL tall beaker, add 10mL of hydrochloric acid-nitric acid mixture [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of nitric acid (ρ is about 1.40g / mL)], add 0.2g of potassium chlorate, leave at room temperature for 30min, and heat slowly until the dissolution reaction stops. Add 5.0mL of perchloric acid, heat until white smoke comes out, and cool slightly. Add 5.0mL of hydrochloric acid (ρ is about 1.19g / mL), continue heating until there is no white smoke from perchloric acid and the solution is dry. After cooling, add 10mL of hydrochloric acid [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of water], heat to dissolve the dried salts, cool to room temperature, and transfer the solution to the main reduction bottle. Add 30mL and 10mL of reducing solvent to the main reduction bottle and the secondary reduction bottle respectively: hydroiodic acid-hypophosphorous acid solution (add 50mL of glacial acetic acid (ρ is about 1.50g / mL) and 25g of sodium hypophosphite to 200mL of hydroiodic acid (ρ is about 1.50g / mL)), add 10mL of water to the wash bottle, add 50mL of zinc acetate (0.1mol / L) absorption liquid to the 100mL absorption bottle, connect the pipeline, pass cooling water, control the nitrogen flow rate to 80mL / min, pass nitrogen for 5min, first heat the secondary reduction bottle, and when the solution reaches a slight boil, heat the main reduction bottle to keep the solution in a slight boiling state for 30min. After distillation is completed, remove the absorption bottle and add 10mL N,N-dimethyl-p-phenylenediamine hydrochloride (2g / L), cover the bottle stopper, shake gently, open the bottle stopper, immediately add 2.0mL ferric chloride hydrochloric acid solution (20g / L), add 2mL hydrochloric acid (ρ is about 1.19g / mL), cover the bottle stopper, rinse the absorption bottle wall with water, shake well, let it stand for 15min, dilute with water to the scale, and shake well again. At 680nm on a spectrophotometer, use a 1cm colorimetric dish to measure its absorbance with air or water as a reference. After subtracting the absorbance of the blank prepared with the sample, the sample absorbance is 0.423. From the working curve measured by the above system using the standard solution prepared with potassium sulfate, the corresponding sulfur content is 27.75μg. According to the formula The calculated sulfur content in the sample is 0.0056%. In the formula, m1: sulfur content in the sample found from the working curve, μg; m: sample mass, g.

[0081] Embodiment 4:

[0082] This embodiment is an analysis process of trace sulfur content in alloy steel. Weigh 0.5034g of sample in a 400mL tall beaker, add 10mL of hydrochloric acid-nitric acid mixture [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of nitric acid (ρ is about 1.40g / mL)], add 0.2g of potassium chlorate, leave at room temperature for 30min, and heat slowly until the dissolution reaction stops. Add 5.0mL of perchloric acid, heat until white smoke comes out, and cool slightly. Add 5.0mL of hydrochloric acid (ρ is about 1.19g / mL), continue heating until there is no white smoke from perchloric acid and the solution dries up. After cooling, add 10mL of hydrochloric acid [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of water], heat to dissolve the dried salts, cool to room temperature, transfer the solution to a 50mL volumetric flask, and dilute to the mark with water. Take 5.00mL of the solution in the main reduction bottle. Add 30mL and 10mL of reducing solvent into the main reduction bottle and the secondary reduction bottle respectively: hydroiodic acid-hypophosphorous acid solution (add 50mL hypophosphorous acid (ρ is about 1.40g / mL) into 300mL hydroiodic acid (ρ is about 1.70g / mL)), add 10mL of water into the wash bottle, add 50mL of zinc acetate (0.2mol / L) absorption liquid into the 100mL absorption bottle, connect the pipeline, pass cooling water, control the nitrogen flow rate to 100mL / min, pass nitrogen for 5min, first heat the secondary reduction bottle, when the solution reaches a slight boil, heat the main reduction bottle, keep the solution in a slight boiling state for 30min, after distillation is completed, remove the absorption bottle, add 10mL N,N-dimethyl-p-phenylenediamine hydrochloride (2g / L), cover the bottle stopper, shake gently, open the bottle stopper, immediately add 1.0mL ferric chloride hydrochloric acid solution (20g / L), add 2mL hydrochloric acid (ρ is about 1.19g / mL), cover the bottle stopper, rinse the absorption bottle wall with water, shake well, let it stand for 15min, dilute with water to the scale, and shake well again. At 680nm on a spectrophotometer, use a 1cm colorimetric dish to measure its absorbance with air or water as a reference. After subtracting the absorbance of the blank prepared with the sample, the sample absorbance is 0.345. From the working curve measured by the above system using the standard solution prepared with potassium sulfate, the corresponding sulfur content is 25.75μg. According to the formula The calculated sulfur content in the sample is 0.051%. In the formula, m1 is the sulfur content in the sample found from the working curve, μg; m is the mass of the sample taken, g.

[0083] Embodiment 5:

[0084] This embodiment is an analysis process of trace sulfur content in carbon steel. Weigh 1.0200g of sample into a 400mL tall beaker, add 10mL of hydrochloric acid-nitric acid mixture [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of nitric acid (ρ is about 1.40g / mL)], leave at room temperature for 30 minutes, and slowly heat until the dissolution reaction stops. Add 5.0mL of perchloric acid, heat until white smoke appears, and cool slightly. Add 5.0mL of hydrochloric acid (ρ is about 1.19g / mL), continue heating until there is no white smoke from perchloric acid and the solution is dry. After cooling, add 10mL of hydrochloric acid [1 volume of hydrochloric acid (ρ is about 1.19g / mL) and 1 volume of water], heat to dissolve the dried salts, cool to room temperature, and transfer the solution to the main reduction bottle. Add 20mL and 5mL of reducing solvent: hydroiodic acid-hypophosphorous acid solution (add 50mL of hypophosphorous acid (ρ is about 1.40g / mL) to 200mL of hydroiodic acid (ρ is about 1.70g / mL)) to the main reduction bottle and the secondary reduction bottle, respectively. Add 10mL of water to the wash bottle, add 8mL of sodium hydroxide (0.08mol / L) absorption liquid to the 20mL absorption bottle, connect the pipeline, pass cooling water, control the nitrogen flow rate to 100mL / min, pass nitrogen for 5min, first heat the secondary reduction bottle, and when the solution reaches a slight boil, heat the main reduction bottle to keep the solution in a slight boiling state for 30min. After distillation is completed, remove the absorption bottle, and add 2mL N,N-dimethyl-p-phenylenediamine hydrochloride (2g / L), cover the bottle stopper, shake gently, open the bottle stopper, immediately add 0.5mL ferric chloride hydrochloric acid solution (10g / L), add 1mL hydrochloric acid (ρ is about 1.19g / mL), cover the bottle stopper, rinse the absorption bottle wall with water, shake well, let it stand for 15min, dilute with water to the scale, and shake well again. At 680nm on a spectrophotometer, use a 2cm colorimetric dish to measure its absorbance with air or water as a reference. After subtracting the absorbance of the blank prepared with the sample, the sample absorbance is 0.278. From the working curve measured by the above system using the standard solution prepared with potassium sulfate, the corresponding sulfur content is 3.90μg. According to the formula The calculated sulfur content in the sample is 0.0004%. In the formula, m1: sulfur content in the sample found from the working curve, μg; m: sample mass, g.

[0085] The results of the present invention and the standard values ​​are compared, and the results are basically consistent, with a relative deviation of no more than 14.3%. The comparison of the results of the present invention and the standard values ​​is shown in Table 1 below:

[0086] Table 1

[0087] Sulfur mass fraction % Method of the present invention Standard value Relative deviation, % Sample 1 0.0035 0.0036 1.4 Sample 2 0.00048 0.00046 2.1 Sample 3 0.00082 0.00080 1.2 Sample 4 0.024 0.028 7.7 Sample 5 0.082 0.080 1.2

[0088] Embodiment 6:

[0089] By examining the precision test of the present invention, it is found that the results have good repeatability and the relative deviation of parallel determination is no more than 8.6%. The precision results of the present invention are shown in Table 2 below:

[0090] Table 2

[0091]

[0092]

[0093] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for determining the sulfur content in steel materials, characterized in that: The method comprises: The substance to be tested that has undergone preliminary treatment is placed in the main reduction unit for first reduction to obtain a first reducing gas; Passing the first reducing gas into a secondary reducing unit for a second reduction to obtain a second reducing gas, wherein the reducing property of the reducing agent in the second reducing unit is the same as that of the reducing agent in the first reducing unit; Passing the second reducing gas into a gas scrubbing unit for cleaning to obtain a purified sulfur-containing gas; Absorbing the purified sulfur-containing gas to form a solution; obtaining the absorbance of the solution; The sulfur content in the substance to be tested is determined based on the absorbance of the solution.

2. The method for determining the sulfur content in steel-based materials according to claim 1, characterized in that: The reducing agent in the secondary reduction unit is a phosphoric acid-stannous phosphate mixed solution or a hydroiodic acid-hypophosphorous acid mixed solution.

3. The method for determining the sulfur content in steel-based materials according to claim 2, characterized in that: The concentration of the phosphoric acid-stannous phosphate mixed solution is prepared by adding 20g to 40g of stannous phosphate into 150mL to 350mL of phosphoric acid (ρ is 1.70g / mL) solution.

4. The method for determining the sulfur content in steel-based materials according to claim 2, characterized in that: The volume ratio of hydroiodic acid to hypophosphorous acid in the hydroiodic acid-hypophosphorous acid mixed solution is (2-8):1, wherein the mass fraction of hydroiodic acid is 57% (ρ is 1.70 g / mL), and the mass fraction of hypophosphorous acid is about 50% (ρ is 1.40 g / mL).

5. The method for determining the sulfur content in steel-based materials according to claim 2, characterized in that: The volume of the main reduction unit is 10 mL to 50 mL.

6. The method for determining the sulfur content in steel-based materials according to any one of claims 1 to 5, characterized in that: The volume of the secondary reduction unit is 5 mL to 30 mL.

7. The method for determining the sulfur content in steel-based materials according to any one of claims 1 to 5, characterized in that: The water used to wash the second reducing gas in the washing unit is experimental water, and the volume is 8 mL to 100 mL.

8. The method for determining the sulfur content in steel-based materials according to any one of claims 1 to 5, characterized in that: The absorbent used for absorbing the purified sulfur-containing gas includes sodium hydroxide solution, zinc acetate solution or a mixed solution of sodium hydroxide and zinc acetate.

9. A device for measuring sulfur content in steel-based materials, characterized in that: The device comprises: Main recovery unit, A secondary reduction unit connected to the gas outlet of the primary reduction unit; A gas scrubbing unit connected to the gas outlet of the secondary reduction unit; An absorption unit connected to the gas outlet of the scrubbing unit; The detection unit is used to detect the liquid at the liquid outlet of the absorption unit.

10. The device for measuring sulfur content in steel-based materials according to claim 9, characterized in that: It also includes return pipes; The main reduction unit and the secondary reduction unit are both provided with the reflux pipeline.

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