Detection method for apparent porosity of sintered ore

Abstract

The invention relates to a method for detecting the apparent porosity of sinter, and mainly solves the technical problem that the porosity of the sinter cannot be accurately measured in the prior art. The invention relates to a method for detecting apparent porosity of sintered ore, which comprises the following steps of: 1) preparing a sample, screening the sintered ore into different size fractions, and preparing 2kg of sintered ore sample according to the weight percentage of the sintered ore with three size fractions of 10-16mm, 16-25mm and 25-40mm; 2) cleaning and drying the sample; (3) test soaking: soaking the sample in water in a vacuum state, and then soaking in a normal pressure state, so that the sample adsorbs water to a saturated state; 4) weighing the sample, namely suspending and soaking the sample which adsorbs water to a saturated state in water, then weighing, and calculating the buoyancy weight and the wet weight of the sample; and 5) calculating the apparent porosity of the sample. The method is simple in process, easy and convenient to operate and convenient to implement, and the apparent porosity of the sintered ore can be rapidly and accurately measured.

Description

Technical Field

[0001] The present invention relates to a detection method, in particular to a detection method for the apparent porosity of sintered ore, belonging to the technical field of physical and chemical inspection in iron and steel metallurgy. Background Art

[0002] Sintered ore is an artificial lump ore formed by high-temperature heating of various powdered iron-containing raw materials, fuels and fluxes under the condition of incomplete melting. It is the main raw material for blast furnace ironmaking, accounting for about 80% of the burden structure, and its quality has an important impact on blast furnace smelting. During the sintering process, different minerals in the sintering raw materials generate low-melting-point compounds through solid-phase reactions, form a liquid phase under high-temperature conditions, and the bonding phase generated during the cooling process effectively consolidates the surrounding core ore, finally forming sintered ore. Sintered ore is usually regarded as composed of two parts: a matrix and pores. The matrix includes magnetite and hematite that make up the iron mineral phase, and calcium ferrite, silicate and vitreous body that make up the bonding phase, while the pores refer to various pore structures in the sintered ore.

[0003] Previous studies have shown that the porosity of sintered ore is an important factor directly affecting the permeability during the sintering process, the reducibility and strength of the sintered ore product. Therefore, the porosity is not only the main index for evaluating the quality of sintered ore, but also an important basis for evaluating the rationality of the sintering process and optimizing the sintering process. However, there is currently no standard for detecting the porosity of sintered ore in China, and no steel enterprises and research institutions have applied for relevant patents on the detection method of the porosity of sintered ore. Therefore, there is no good method to accurately and conveniently measure the porosity of sintered ore.

[0004] The Chinese patent application document with the publication number CN100575921C discloses a detection method for the pore characteristics of iron ore. An automatic nitrogen adsorption instrument is used to obtain the pore distribution of the iron ore sample and the total volume of pores contained in the iron ore sample per unit mass, and then the porosity of the iron ore sample is calculated in combination with the true volume of the iron ore sample. This method requires the sample to be degassed in the degassing station of the automatic nitrogen adsorption instrument for more than 13 hours, and then the sample is loaded into the pore analysis station under the condition of a constant temperature of -195°C for pore analysis. This method has a long test period and relatively strict test conditions. The automatic nitrogen adsorption instrument generally requires the sample to be ground into fine powder below 200 meshes. Using this method will damage the pore structure of the sintered ore, so it is not suitable for detecting the porosity of sintered ore. Summary of the Invention

[0005] The present invention precisely aims at the problems existing in the prior art, provides a detection method for the apparent porosity of sintered ore, mainly solves the technical problem that the porosity of the existing sintered ore cannot be accurately measured, and has important significance for optimizing the sintering process and controlling the quality of sintered ore.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows: Prepare an appropriate amount of sinter ore specimens as required. After cleaning and drying the specimens, first weigh the weight of the dry specimens, then evacuate the air in the pores of the specimens under vacuum conditions and inject water until fully saturated; then place the specimens saturated with adsorbed water in a wire mesh basket and hang them in water, and weigh the floating weight of the specimens in water; finally, take out the specimens in the wire mesh basket and weigh the wet weight of the specimens. The difference between the wet weight of the specimens and the weight of the dry specimens can calculate the volume of the pores in the specimens; the difference between the wet weight of the specimens and the floating weight of the specimens can calculate the total volume of the specimens, and finally calculate the ratio of the volume of the pores in the specimens to its total volume, that is, the apparent porosity of the specimens can be obtained.

[0007] A method for detecting the apparent porosity of sinter ore, comprising the following steps:

[0008] Step 1: Specimen preparation. Take about 30 - 60 kg of sinter ore, screen the sinter ore using square-hole sieves with apertures of 40 mm, 25 mm, 16 mm, and 10 mm, discard small pieces less than 10 mm and large pieces greater than 40 mm, and then weigh the remaining sinter ore in three particle size grades of 10 - 16 mm, 16 - 25 mm, and 25 - 40 mm, calculate the weight percentage of each particle size grade, and prepare a sinter ore specimen of about 2 kg according to the weight percentage of each particle size grade.

[0009] Step 2: Specimen drying. Blow the sinter ore specimen with compressed air to remove the dust on the surface, then put it into a drying oven and dry it at 105 - 120 °C for 3 h. Take out the specimen from the drying oven, cool it for 10 - 20 min, and weigh the mass m of the dry specimen 1 。

[0010] Step 3: Specimen soaking. Place the weighed specimen in a glass dish, then put the glass dish into a vacuum chamber, evacuate to a residual pressure less than 2.66 kPa. Inject water into the glass dish to completely submerge the specimen, and soak it in water for 20 - 40 min. Release the pressure in the vacuum chamber to atmospheric pressure, and let the specimen soak for another 30 - 50 min under atmospheric pressure.

[0011] Step 4: Specimen weighing. Hang the wire mesh basket on the hook under the electronic balance and soak it in a water-containing container, and weigh the floating weight m of the wire mesh basket in water 2 。Take out the specimen saturated with adsorbed water from the vacuum chamber and put it into the wire mesh basket, then hang the wire mesh basket and the specimen on the hook under the electronic balance and soak it in a water-containing container, and weigh the floating weight m of the two 3 。Take the wire mesh basket and the specimen out of the water, drip water for 20 - 40 s, then take out the specimen and weigh the wet weight m of the specimen 4 。

[0012] Step 5: Result calculation. The apparent porosity P of the specimen can be calculated according to formula (1); the m1 , m 2 , m 3 , m 4 The measuring units of are the same.

[0013]

[0014] In steps (3) and (4) of the present invention, the water must be distilled water and the test is carried out at a laboratory temperature of 23 ± 5°C.

[0015] In step (4) of the present invention, the wire mesh basket is made of stainless steel wire. The aperture of the basket is 5 - 8 mm, the bottom diameter is 200 - 300 mm, and the height is 150 - 200 mm. Two semi-circular bent rods with the same diameter as the wire mesh basket are welded on the wire mesh basket. The bent rods are perpendicular to each other and are fixed together by a loop eye bolt hook. The loop eye bolt hook is connected to the lower hook of the electronic balance. The present invention has the following positive effects compared with the prior art:

[0016] The detection method of the apparent porosity of sintered ore provided by the present invention can quickly and accurately measure the apparent porosity of sintered ore, which is of great significance for optimizing the sintering process and controlling the quality of sintered ore;

[0017] The device used in the method of the present invention has a simple structure, low processing cost, simple operation process, is easy to implement, accurate and reliable, low detection cost, and can also be used for the porosity detection of other similar products, with a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 : Schematic diagram of sample weighing.

[0019] In the figure: 1 - electronic balance; 2 - hook; 3 - loop eye bolt hook; 4 - wire mesh basket; 5 - water container; 6 - sintered ore sample; 7 - water. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To deepen the understanding of the present invention, the following detailed description is given with reference to the accompanying drawings for this embodiment.

[0021] Example 1: Refer to Figure 1 , a detection method for the apparent porosity of sintered ore, comprising the following steps:

[0022] Step 1: Sample preparation. Take about 50 kg of sintered ore and screen the sintered ore using square hole sieves with apertures of 40 mm, 25 mm, 16 mm, and 10 mm. Discard small pieces less than 10 mm and large pieces larger than 40 mm. Then weigh the remaining sintered ore in three particle size grades of 10 - 16 mm, 16 - 25 mm, and 25 - 40 mm, calculate the weight percentage of each particle size grade, and prepare about 2 kg of sintered ore sample 6 according to the weight percentage of each particle size grade.

[0023] Step 2: Specimen drying. The sintered ore specimen 6 is purged with compressed air to remove the dust on the surface, and then placed in a drying oven and dried at 110°C for 3 h. The specimen 6 is taken out of the drying oven, cooled for 15 min, and the mass m of the dried specimen 6 is weighed. 1 ,

[0024] Step 3: Specimen soaking. The weighed specimen 6 is placed in a glass dish, and then the glass dish is placed in a vacuum chamber. The vacuum is pumped until the remaining pressure is less than 2.66 kPa. Water is injected into the glass dish to completely submerge the specimen 6, and it is soaked in water for 30 min. The pressure in the vacuum chamber is released to atmospheric pressure, and the specimen 6 is soaked for another 40 min under atmospheric pressure.

[0025] Step 4: Specimen weighing. The wire mesh basket 4 is hung on the hook 2 under the electronic balance 1 and soaked in the water container 5. The floating weight m of the wire mesh basket 4 in the water 7 is weighed. 2 . The specimen 6 saturated with adsorbed water is taken out of the vacuum chamber and placed in the wire mesh basket 4. Then the wire mesh basket 4 and the specimen 6 are hung on the hook 2 under the electronic balance 1 and soaked in the water container 5, and the floating weight m of the two is weighed. 3 . The wire mesh basket 4 and the specimen 6 are lifted out of the water surface 7. After dripping water for 30 s, the specimen 6 is taken out and the wet weight m of the specimen 6 is weighed. 4 ,

[0026] Step 5: Result calculation. The apparent porosity P of the specimen 6 can be calculated according to formula (1); the m 1 , m 2 , m 3 , m 4 have the same unit of measurement.

[0027]

[0028] In step 3 and step 4 of the present invention, the water 7 must be distilled water, and the test is carried out at the laboratory temperature of 25°C. In step 4 of the present invention, the wire mesh basket is made of stainless steel wire, the aperture of the basket is 6 mm, the bottom diameter is 200 mm, and the height is 150 mm; the wire mesh basket is provided with a hanging rope that can be hung (two semi-circular bent rods are welded on the wire mesh basket, with the same diameter as the wire mesh basket, the bent rods are perpendicular to each other and fixed together by a sheep's eye bolt hook, and the sheep's eye bolt hook is connected to the hook under the electronic balance).

[0029] The specific test data and calculation results of this embodiment are shown in Table 1.

[0030] Table 1 Detection results of the porosity of the specimen in the embodiment of the present invention

[0031] Specimen number <![CDATA[m 1 / g]]> <![CDATA[m 2 / g]]> <![CDATA[m 3 / g]]> <![CDATA[m 4 / g]]> P / ％ Example 1 2000.2 328.6 1856.9 2144.8 23.45

[0032] As can be seen from Table 1, the present invention provides a method for detecting the apparent porosity of sinter, which can quickly and accurately measure the apparent porosity in sinter, and is of great significance for optimizing the production of sintering process.

[0033] It should be noted that the above embodiments are not used to limit the protection scope of the present invention, and equivalent transformations or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. A method for detecting the apparent porosity of sinter, characterized in that, the method comprises the following steps: Step 1: Specimen preparation, Step 2: Specimen drying, Step 3: Specimen soaking, Step 4: Specimen weighing, Step 5: Result calculation.

2. The method for detecting the apparent porosity of sinter according to claim 1, characterized in that, Step 1: Specimen preparation is as follows: Take about 30 - 60 kg of sinter, screen the sinter using square-hole sieves with pore sizes of 40 mm, 25 mm, 16 mm, and 10 mm, discard small pieces smaller than 10 mm and large pieces larger than 40 mm, and then weigh the remaining sinter in three particle size grades of 10 - 16 mm, 16 - 25 mm, and 25 - 40 mm, calculate the weight percentage of each particle size grade, and prepare a sinter specimen of about 2 kg according to the weight percentage of each particle size grade.

3. The method for detecting the apparent porosity of sinter according to claim 2, characterized in that, Step 2: Sample drying. Blow the sinter sample with compressed air to remove the dust on the surface, then put it into the drying oven and dry it at 105 - 120 °C for 3 h. Take the sample out of the drying oven, cool it for 10 - 20 min, and weigh the mass m of the dried sample 1 .

4. The method for detecting the apparent porosity of sinter according to claim 3, characterized in that, Step 3: Specimen soaking, Place the weighed specimen in a glass dish, then put the glass dish into a vacuum chamber, evacuate to a residual pressure less than 2.66 kPa, pour water into the glass dish to completely submerge the specimen, and soak in water for 20 - 40 min, release the pressure in the vacuum chamber to atmospheric pressure, and let the specimen soak for another 30 - 50 min under atmospheric pressure.

5. The method for detecting the apparent porosity of sinter according to claim 4, characterized in that, Step 4: Sample weighing. Hang the wire mesh basket on the hook under the electronic balance and immerse it in the water-containing container, and weigh the floating weight m of the wire mesh basket in water. 2 , Take out the sample saturated with adsorbed water from the vacuum chamber, put it into the wire mesh basket, then hang the wire mesh basket and the sample on the hook under the electronic balance and immerse them in the water-containing container, and weigh the floating weight m of both. 3 , Lift the wire mesh basket and the sample out of the water surface. After dripping water for 20 - 40 s, take out the sample and weigh the wet weight m of the sample. 4 .

6. The method for detecting the apparent porosity of sinter according to claim 5, characterized in that, Step 5: Result calculation. The apparent porosity P of the specimen can be calculated according to formula (1); the 1 , 2 , 3 , 4 have the same unit of measurement.

7. The method for detecting the apparent porosity of sinter according to claim 6, characterized in that, the water in steps (3) and (4) is distilled water, and the test is carried out at a laboratory temperature of 23 ± 5 °C.

8. The method for detecting the apparent porosity of sinter according to claim 6, characterized in that, the wire mesh basket in step (4) is made of stainless steel wire, the pore size of the basket is 5 - 8 mm, the bottom diameter is 200 - 300 mm, and the height is 150 - 200 mm; Two semi-circular bent rods are welded on the wire mesh basket, with the same diameter as the wire mesh basket, the bent rods intersect perpendicularly, and are fixed together by a sheep's eye bolt hook, and the sheep's eye bolt hook is connected to the lower hook of an electronic balance.

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