Method for measuring water yield of hot-pressed briquettes

Abstract

The application provides a kind of hot-pressed iron block water yield determination method, to solve the problem of low accuracy of hot-pressed iron block water yield determination method in prior art.The application provides a kind of hot-pressed iron block water yield determination method, comprising the following steps: (1) hot-pressed iron block is subjected to slag-iron separation treatment to obtain separated iron block and separated slag particles; (2) the first iron content determination treatment is carried out on the separated iron block by using a direct-reading spectrometer to obtain the iron content of the separated iron block; the second iron content determination treatment is carried out on the separated slag particles by potassium dichromate titration method to obtain the iron content of the separated slag particles; according to the mass of the hot-pressed iron block, the mass of the separated iron block, the iron content of the separated iron block and the iron content of the separated slag particles, the water yield of the hot-pressed iron block is obtained; the determination method has high accuracy and simple operation process.

Description

Technical Field

[0001] This invention belongs to the field of detection and analysis technology, specifically relating to a method for determining the water output rate of hot-pressed iron blocks. Background Technology

[0002] Currently, scrap steel prices are high, exceeding their original value. Therefore, some steel companies have begun using hot-pressed iron blocks. Hot-pressed iron blocks are produced using direct reduction technology for ore powder, achieving an iron grade of 67.5%–68% after beneficiation. The reducing gas used is natural gas, which is processed into H2 and CO after reforming. The ore and reducing gas flow counter-currently, undergoing four stages of reduction to obtain sponge iron, which is then hot-pressed to obtain the final product—hot-pressed iron.

[0003] Hot-pressed iron possesses the characteristics common to ordinary sponge iron: high purity, low content of harmful impurities, which is beneficial for the production of high-quality steel; uniform quality; high strength; low pulverization rate; and is more conducive to safe transportation and open-air storage. It also boasts high steel production yield, low gangue content, and low smelting energy consumption. Furthermore, hot-pressed iron blocks have a wide range of applications, commonly used in electric arc furnace production, and also applied in various smelting processes such as blast furnaces, converters, and electric arc furnaces. Its advantages include: 1. Alleviating the shortage of scrap steel resources. 2. Shortening the smelting cycle and increasing output. 3. The rapid melting speed of hot-pressed iron blocks is beneficial for the early slag formation process in converters. 4. The stable chemical composition of hot-pressed iron blocks is advantageous for operation.

[0004] The water yield of hot-pressed iron blocks is an important factor in evaluating their quality and serves as a crucial standard for company procurement. Furthermore, accurate measurement of hot-pressed iron block water yield plays a vital role in cost calculations during converter iron output. However, currently, there is no industry standard that can accurately analyze the water yield of hot-pressed iron blocks.

[0005] Typically, the determination of the water yield of hot-pressed iron blocks involves using an electromagnetically inductively generated alternating magnetic field to penetrate a graphite crucible, melting the iron-containing material and separating the slag from the iron. The water yield is then determined by calculating the proportion of iron in the sample. However, this method has drawbacks. During the controlled melting time, the presence of graphite carbon in the sample and impurities such as C, Mn, and Si in the sample can undergo reduction reactions, causing these elements to enter the molten iron and increase the water yield. Furthermore, some iron may enter the slag during the iron-slag separation process, affecting the measurement results.

[0006] In conclusion, there is an urgent need for a method that can accurately determine the water output rate of hot-pressed iron blocks. Summary of the Invention

[0007] This invention provides a method for determining the water yield of hot-pressed iron blocks, which solves the problem of low accuracy in existing methods for determining the water yield of hot-pressed iron blocks.

[0008] This invention provides a method for determining the water yield of a hot-pressed iron block, comprising the following steps:

[0009] (1) The hot-pressed iron block is subjected to slag-iron separation treatment to obtain separated iron block and separated slag particles;

[0010] (2) The iron content of the separated iron block was determined by a direct-reading spectrometer; the iron content of the separated slag particles was determined by potassium dichromate titration.

[0011] The water yield of the hot-pressed iron block is obtained based on the mass of the hot-pressed iron block, the mass of the separated iron block, the iron content of the separated iron block, and the iron content of the separated slag particles.

[0012] Compared with the prior art, the advantages of the present invention are: by using a direct-reading spectrometer to deduct impurity elements from the hot-pressed iron blocks after slag-iron separation, and then by using potassium dichromate redox titration to analyze the iron content in the separated slag particles, the iron is combined and calculated to obtain the water yield of the hot-pressed iron blocks. This method has high accuracy in analysis results and is simple and easy to control in operation.

[0013] Furthermore, based on the mass of the hot-pressed iron block, the mass of the separated iron block, the iron content of the separated iron block, and the iron content of the separated slag particles, the water yield of the hot-pressed iron block is obtained, including calculating the water yield of the hot-pressed iron block according to formula (1).

[0014] W = m2 / m1 × 100% × Fe1 + (m1 - m2) / m1 × 100% × Fe2 Equation (1)

[0015] In the formula, W is the water yield of the hot-pressed iron block, in %; m1 is the mass of the hot-pressed iron block, in g; m2 is the mass of the separated iron block, in g; Fe1 is the iron content of the separated iron block, in %; and Fe2 is the iron content of the separated slag particles, in %.

[0016] Furthermore, before step (1), the following steps are also included: placing the hot-pressed iron block in an ultrasonic induction furnace for melting treatment, and then performing slag-iron separation treatment.

[0017] Furthermore, the melting process includes a first melting process of 5-6 minutes at an oscillating current of 95-100A, followed by a second melting process of 8-9 minutes at an oscillating current of 240-250A, until the slag particles are completely separated from the molten iron. After cooling, the separated iron block and the separated slag particles are obtained.

[0018] Further, before step (2), the separated iron block is subjected to cutting and grinding processes in sequence to obtain the cut surface of the separated iron block, and the cut surface of the separated iron block is subjected to the first iron content determination process.

[0019] Furthermore, before step (2), the particle size of the separated slag particles is not less than 160 mesh.

[0020] Furthermore, the second iron content determination process involves dissolving the separated slag particles in hydrochloric acid at a temperature of 300–400°C; and reducing the sample with stannous chloride and titanium trichloride, using sodium diphenylamine sulfonate as the indicator. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] This invention provides a method for determining the water yield of a hot-pressed iron block, comprising the following steps:

[0023] (1) The hot-pressed iron block is subjected to slag-iron separation treatment to obtain separated iron block and separated slag particles;

[0024] (2) The iron content of the separated iron block was determined by first using a spectrometer; the iron content of the separated slag particles was determined by second using potassium dichromate titration.

[0025] The water yield of the hot-pressed iron block is obtained based on the mass of the hot-pressed iron block, the mass of the separated iron block, the iron content of the separated iron block, and the iron content of the separated slag particles.

[0026] In the process, weigh approximately 700-800g of the hot-pressed iron block sample (using a No. 8 crucible), denoted as m1, and place it in a graphite crucible. Use a special tool to place the graphite crucible into the induction furnace. Adjust the oscillation current to approximately 100A for about 5 minutes, then continue adjusting the oscillation current to full load (240-250A) for about 8 minutes. After the slag in the sample floats to the surface and completely separates from the molten iron, rotate the power adjustment knob to zero. After stabilizing for about 10 seconds, remove the sample with a special tool and place it in a fixed position. Allow it to cool naturally until the graphite crucible turns black. Then, move it to a designated outdoor location and smash the graphite crucible with a hammer. Remove the iron block and place it in a water tank filled with cold water for rapid cooling. After 30 seconds, remove it and place it on refractory bricks to cool naturally to room temperature. Remove the surface slag and weigh the separated iron block using a balance, denoted as m2.

[0027] The separated iron blocks were cut into flat surfaces, then ground smooth with a belt sander. The iron content of the cut surfaces was then determined using an ARL3460 direct-reading spectrometer. Two to three parallel measurements were performed on different cut surfaces, and the average value was recorded as Fe1.

[0028] The separated residue samples were ground and sieved to ensure a particle size of not less than 160 mesh. Then, (0.2000±0.0001) g of the sample was weighed and dissolved in hydrochloric acid at a temperature of 300–400 °C. The sample was then reduced with stannous chloride and titanium trichloride, and sodium diphenylamine sulfonate indicator was added. The solution was titrated with potassium dichromate standard solution to determine the second iron content, and the result was recorded as Fe2. The potassium dichromate titration method was performed in accordance with GB / T 6730.65-2009.

[0029] The water yield of the hot-pressed iron block is calculated according to formula (1):

[0030] W = m2 / m1 × 100% × Fe1 + (m1 - m2) / m1 × 100% × Fe2 Equation (1)

[0031] In the formula, W is the water yield of the hot-pressed iron block, in %; m1 is the mass of the hot-pressed iron block, in g; m2 is the mass of the separated iron block, in g; Fe1 is the iron content of the separated iron block, in %; and Fe2 is the iron content of the separated slag particles, in %.

[0032] The following is a detailed description of a method for determining the water output rate of a hot-pressed iron block provided by the present invention through specific embodiments.

[0033] Example 1

[0034] (1) Sample melting and slag-iron separation: Weigh 800±0.01g of hot-pressed iron block sample (using No. 8 crucible) and record it as m1. Place it in a graphite crucible and use a special tool to place the graphite crucible into the induction furnace. Adjust the oscillation current to about 100A for about 5 minutes, then continue to adjust the oscillation current to the full load of 250A for about 8 minutes. After the slag in the sample floats up and is completely separated from the molten iron, rotate the power adjustment knob to zero. Stabilize for about 10 seconds, then remove it with a special tool and place it in a fixed position. After it cools naturally and the graphite crucible turns black, move it to a designated outdoor location and smash the graphite crucible with a hammer. Remove the iron block and place it in a water tank filled with cold water for rapid cooling. After 30 seconds, remove it and place it on refractory bricks to cool naturally to room temperature. Remove the surface slag and weigh the iron block with a balance. The weight is 752.05g, and record it as m2.

[0035] W (including impurity elements) = m2 / m1 × 100% = 752.05 / 800 × 100% = 94.01%;

[0036] (2) Removal of impurities from iron: The separated iron blocks were cut into flat surfaces, then ground flat with a belt sander, and the iron content was determined using an ARL3460 direct-reading spectrometer. The sample was measured in parallel 2 to 3 times, and the average value was recorded as Fe1. The measured Fe1 was 96.69%.

[0037] W (excluding iron in slag) = m2 / m1 × 100% × Fe1 = 90.90%;

[0038] (3) Determination of iron content in slag: The separated slag particles were ground and sieved. The sample particle size was ≥160 mesh. Then, (0.1999) g of sample was weighed and dissolved in hydrochloric acid at 400℃. The sample was reduced with 60 g / L stannous chloride and 5% titanium trichloride. 2 g / L sodium diphenylamine sulfonate was used as an indicator. The sample was titrated with 0.0033 mol / L potassium dichromate standard solution. The standard solution consumed was 20.66 ml. Blank and standard sample determinations were performed at the same time. The iron content was determined by the content of the standard sample and the titration number. The sample was measured in parallel 2 to 3 times and the average value was taken. The result was recorded as Fe2. The measured Fe2 was 11.54%.

[0039] The water yield of the hot-pressed iron block is calculated according to formula (1):

[0040] W=m2 / m1×100%×Fe1+(m1-m2) / m1×100%×Fe2

[0041] =752.05 / 800×100%×96.69%+47.95 / 800×100%×11.54%

[0042] =91.59%.

[0043] Examples 2-15

[0044] The same hot-pressed iron block samples from different batches as in Example 1 were used, and the measurement methods were the same as in Example 1.

[0045] Experimental Example 1

[0046] X-ray spectroscopy analysis was performed on the different samples in the above embodiments, including the following steps:

[0047] Different batches of hot-pressed iron block samples were drilled using a bench drill. Before drilling, the surface oxide layer was removed. Drilling was performed on the upper and lower surfaces and sides of the sample. After grinding the sample to the particle size required by the instrument, 4 ± 0.0002 g of mixed solvent (sodium carbonate: boric acid: potassium carbonate mass ratio of 3:2:1) was weighed into a quantitative filter paper. 0.2 ± 0.0002 g of hot-pressed iron block sample was added and mixed thoroughly. The sample was then wrapped into spherical shapes using filter paper. The spherical samples were placed in a pre-oxidized graphite crucible and baked in a muffle furnace heated to 950°C for 15 minutes. After removal, the crucible was placed in an isolation chamber to cool the graphite. The oxidized spheres of the hot-pressed iron block were removed from the graphite crucible with tweezers and cleaned.

[0048] A secondary melting process was then performed in a platinum dish: 6g of flux (lithium tetraborate:lithium metaborate mass ratio of 67:33) was weighed into the platinum dish, approximately 1g of ammonium iodide was added and mixed thoroughly, and a hot-pressed iron sample ball was added. The platinum dish was then placed in a melting machine and melted at 1050℃ for 900s. After removal and cooling, a molten sample was obtained. The iron content was then determined using an X-ray fluorescence spectrometer with a corresponding standard curve.

[0049] The test results obtained by the determination method provided by the present invention for different samples in the above embodiments and the test results obtained by X-ray spectroscopy analysis in the experimental examples are shown in Table 1.

[0050] Table 1

[0051]

[0052]

[0053] Comparing the results in Table 1, it can be seen that the method for determining the water yield of hot-pressed iron blocks provided by this invention, after deducting impurities using a direct-reading spectrometer and determining the iron element in the slag using the potassium dichromate method, yields a final water yield with an average error of 0.61% compared to the X-ray spectrometer analysis results, which meets the relevant standard requirements. The method provided by this invention has high accuracy, is simple, and has high work efficiency. It also reduces the steps of drilling samples with a bench drill, increases the safety of the operation, and provides strong controllability. The measurement results can be used for trade settlement while ensuring the accuracy of converter batching during steelmaking.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. A method for determining the water yield of a hot-pressed iron block, characterized in that, Includes the following steps: (1) The hot-pressed iron block is subjected to slag-iron separation treatment to obtain separated iron block and separated slag particles; (2) The iron content of the separated iron block was determined by a direct-reading spectrometer; the iron content of the separated slag particles was determined by potassium dichromate titration. The water yield of the hot-pressed iron block is obtained based on the mass of the hot-pressed iron block, the mass of the separated iron block, the iron content of the separated iron block, and the iron content of the separated slag particles.

2. The method for determining the water yield of hot-pressed iron blocks according to claim 1, characterized in that, The process of obtaining the water yield of hot-pressed iron blocks based on the mass of hot-pressed iron blocks, the mass of separated iron blocks, the iron content of separated iron blocks, and the iron content of separated slag particles includes calculating the water yield of hot-pressed iron blocks according to formula (1). W = m2 / m1×100%×Fe1 + (m1-m2) / m1×100%×Fe2 Equation (1) In the formula, W is the water discharge rate of the hot-pressed iron block, in %; m1 is the mass of the hot-pressed iron block, in g; m2 is the mass of the separated iron block, in g; Fe1 is the iron content of the separated iron block, in %; and Fe2 is the iron content of the separated slag particles, in %.

3. The method for determining the water yield of hot-pressed iron blocks according to claim 1, characterized in that, Before step (1), the following steps are also included: placing the hot-pressed iron block in an ultra-high frequency induction furnace for melting treatment, and then performing slag-iron separation treatment.

4. The method for determining the water yield of hot-pressed iron blocks according to claim 3, characterized in that, The melting process includes a first melting process for 5-6 minutes at an oscillating current of 95-100A, followed by a second melting process for 8-9 minutes at an oscillating current of 240-250A, until the slag particles are completely separated from the molten iron. After cooling, the separated iron block and the separated slag particles are obtained.

5. The method for determining the water yield of hot-pressed iron blocks according to claim 1, characterized in that, Before step (2), the separated iron block is cut and ground in sequence to obtain the cut surface of the separated iron block. The cut surface of the separated iron block is then subjected to the first iron content determination process.

6. The method for determining the water yield of hot-pressed iron blocks according to claim 1, characterized in that, Before step (2), the particle size of the separated slag particles shall not be less than 160 mesh.

7. The method for determining the water yield of hot-pressed iron blocks according to claim 1, characterized in that, The second iron content determination process involves dissolving the separated residue particles in hydrochloric acid at a temperature of 300-400°C; reduction is performed using stannous chloride and titanium trichloride, with sodium diphenylamine sulfonate as the indicator.

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