Method for analyzing carbon source in blast furnace fly ash

Abstract

The invention discloses a method for analyzing a carbon source in blast furnace fly ash, which comprises the following steps: step 1, pouring fly ash and inlay powder into a crucible, uniformly mixing, placing in a sample melting device, and stirring while heating until the mixture is sticky; step 2, performing pressure forming on the sticky paste in the step 1 to obtain a thin tablet; 3, polishing is conducted; 4, placing a daub ball which has the same diameter as the thin tablet after being pressed and unfolded on a glass slide; step 5, placing the thin pressing sheet on the upper side of the daub ball, and extruding the daub ball by using a flattening device, so that the daub ball is fully deformed, and the upper side of the thin pressing sheet is parallel to the glass slide; step 6, covering the upper side of the thin tablet with a cover glass, observing by using a lithographic microscope, counting the coal and the coke according to the morphological characteristics of the coal and the coke, and calculating the proportion; chemical reagents are not needed in the whole process, samples are prepared only in a physical mode, no pollutant is discharged, waste acid pollution caused by a chemical separation method is avoided, and the environmental protection cost and personal injury are reduced.

Description

Technical Field

[0001] This invention belongs to the field of carbon source testing in blast furnace dust, and particularly relates to a method for analyzing the carbon source in blast furnace dust. Background Technology

[0002] During the blast furnace smelting process, coke and pulverized coal are used as the main fuels. After high-temperature reaction, they produce dust with a carbon content as high as 24.03% (about 15 kg / ton of iron).

[0003] Existing technologies can optimize coking coal ratios and reduce fuel ratios by analyzing the carbon sources (coal / coke ratio) in dust collector ash, thereby achieving carbon emission reduction targets. Currently, the mainstream methods are chemical separation methods (such as acid washing and flotation) or elemental analysis methods (such as X-ray fluorescence spectroscopy).

[0004] Chemical separation method: Separates coal and coke by utilizing their differences in solubility in acid, and then calculates their proportions by gravimetric method. Elemental analysis method: Indirectly infers the carbon source based on differences in the content of trace elements (such as aluminum and silicon) in coal and coke.

[0005] Chemical separation methods require sample dissolution, and the disposal of waste acid causes environmental pollution. Elemental analysis relies on the elemental correlation of coal / coke, is greatly affected by mineral impurities, has low accuracy, and cannot trace the source at a microscopic level. Summary of the Invention

[0006] The purpose of this invention is to provide a method for analyzing the carbon source in blast furnace dust, in order to solve the problems in existing methods for analyzing the carbon source in blast furnace dust, such as the environmental pollution caused by waste acid in chemical separation methods, the significant interference of mineral impurities on the accuracy of elemental analysis methods, and the inability to achieve microscopic source tracing.

[0007] This invention employs the following technical solution: a method for analyzing the carbon source in blast furnace dust, comprising: Step 1: Take the dust removal ash and embedding powder, pour them into the crucible, mix them well, place them in the melting vessel, heat and stir until they become viscous; Step 2: Transfer the viscous sample from Step 1 to a compression molding machine and press it to form a thin sheet; Step 3: After the thin sheet has cooled completely, polish it with sandpaper; Step 4: Place the clay ball, which has been pressed and unfolded to the same diameter as the thin sheet, onto the glass slide; Step 5: Place the thin sheet on top of the clay lump and press it with a flattener to fully deform the clay lump and make the top of the thin sheet parallel to the glass slide. Step 6: Cover the thin pressed sheet with a coverslip and observe it using a petrographic microscope. Count the coal and coke according to their morphological characteristics and calculate their proportions.

[0008] The beneficial effects of this invention are: This invention requires no chemical reagents throughout the entire process, and samples are prepared solely through physical methods, resulting in no pollutant emissions. It avoids waste acid pollution from chemical separation methods, thereby reducing environmental costs and personnel harm. This invention offers significantly higher accuracy than existing methods, directly distinguishing between coal (irregular edges, abnormal porosity) and coke (porous edges, thin pore walls) based on their morphological and optical characteristics, unaffected by mineral impurities. Furthermore, data reliability is ensured through "multi-sampling point mixing (≥5 points, ≥1kg), testing of 3 parallel samples, and counting using a 30×30 grid (total number of points > 100)." In the example, the coal percentage fluctuation is only 4.44 percentage points. This invention enables microscopic traceability, allowing for the deduction of carbon origins from morphological details (such as the burnout of pulverized coal and the pyrolysis of coke), providing a basis for optimizing blast furnace parameters. At the same time, it requires no expensive equipment, is simple to operate and easy to promote, and helps enterprises to accurately adjust the coking coal ratio and reduce the fuel ratio, achieving a win-win situation of cost reduction and carbon emission reduction. Attached Figure Description

[0009] Figure 1-7 This is a microscopic image from Example 1. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0011] This invention discloses a method for analyzing the carbon source in blast furnace dust, comprising: Step 1: Take the dust removal ash and embedding powder, pour them into the crucible, mix them well, place them in the melting vessel, heat and stir until they become viscous; Step 2: Transfer the viscous sample from Step 1 to a compression molding machine and press it to form a thin sheet; Step 3: After the thin sheet has cooled completely, polish it with sandpaper; Step 4: Place the clay ball, which has been pressed and unfolded to the same diameter as the thin sheet, onto the glass slide; Step 5: Place the thin sheet on top of the clay lump and press it with a flattener to fully deform the clay lump and make the top of the thin sheet parallel to the glass slide. Step 6: Cover the thin pressed sheet with a coverslip and observe it using a petrographic microscope. Count the coal and coke according to their morphological characteristics and calculate their proportions.

[0012] In step 1, the mass ratio of dust removal ash to embedding powder is 1:1.

[0013] In step 3, the sandpaper used is 400-mesh and 800-mesh water-resistant sandpaper.

[0014] Through research conducted by this invention, it has been discovered that the coal and coke in dust collector ash have undergone crushing, combustion, or pyrolysis processes, resulting in morphological differences compared to raw coal and coke. Under an optical microscope or scanning electron microscope, they exhibit the following main characteristics: The morphology of coal is as follows: it consists of amorphous, irregular, flaky particles with irregular edges that are sharper than those of coke particles. It retains the residual characteristics of the microscopic components in the raw coal, such as the light gray to grayish-black, weak luster of the vitrinite and the bright white reflectivity of the inertinite. The pore structure is much smaller than that of coke particles, and the surface appears smooth and mirror-like when viewed under a lens.

[0015] Morphology of the coke: It exhibits a porous, fragmented form or a porous, vesicular structure, with the vesicular structure being more fragmented than the original coke. The pore walls are thin and easily broken, and the edges are often angular or irregular. Optical anisotropy is weakened, and fibrous and flaky structures become incomplete due to fragmentation, often existing in the form of small particles. The surface may be covered with a glassy shell formed by molten minerals, or there may be localized densification areas due to high-temperature sintering. The angular structure at the edges exhibits characteristics of a condensed molten material, appearing dark white under the lens.

[0016] Therefore, in step 6, when observing and distinguishing between coal and coke, the criteria for judging coal are: irregular edges, damaged pores, or pores filled with impurities.

[0017] Therefore, in step 6, when observing and distinguishing between coal and coke, the criterion for judging coke is: porous debris morphology or porous pore structure.

[0018] When collecting samples, collect dust samples from the outlet of the dust removal equipment (gravity dust collector and bag dust collector) of the blast furnace, collect no less than 5 points, mix the samples evenly, and weigh no less than 1 kg.

[0019] Preferably, the analytical method of the present invention is as follows: Step 1: Using the matching standard measuring spoon, take the dust removal ash and embedding powder in a 1:1 (volume ratio) ratio and pour them into the crucible. Mix them well and place them in the melting vessel. Heat and stir at the same time until the mixture becomes viscous.

[0020] Step 2: Quickly transfer the viscous sample into the mold of the compression molding machine and press it. After molding, remove it quickly and let it stand for about 2 minutes. Mark the sample with a number on the side with a white marker.

[0021] Step 3: After the polished sheet has cooled completely, grind it on 400-grit and 800-grit water-resistant sandpaper in sequence; evenly sprinkle coal and rock polishing agent on the polishing cloth, so that the surface of the sample polished sheet is in horizontal contact with the polishing cloth. After polishing, the surface particles are clear and there should be no scratches, oil stains, water stains or other residues. Step 4: Based on the tilt of the sample block, select an appropriate size of clay lump and place it on the glass slide.

[0022] Step 5: Place the sample on the clay lump and press it with a flattener for 3 seconds to fully deform the clay so that the test surface is parallel to the surface of the glass slide. Step 6: Apply the oil evenly to the sample surface, minimizing air bubbles; generally, 1-2 drops are sufficient. Place the sample under a petrographic microscope and establish a 30x30 grid of regular dots on the sample surface. Based on the different characteristics of coal and coke under an optical microscope, count the number of dots of coal and coke falling on the carbonaceous phase and calculate the proportion of coal and coke.

[0023] Three samples were prepared for each test, and the average value was used to represent the proportion of coal and coke in that sample. The total number of coal and coke spots on the carbonaceous phase should be greater than 100, and the test results should be rounded to two decimal places.

[0024] Example 1 A 1kg sample of dust was collected from the outlet of the gravity dust collector of blast furnace No. 1, numbered 20250518-1Z. The sample was mixed and reduced to two 50g portions. One portion was analyzed three times using infrared absorption spectrometry, and the results were 20.58%, 21.12%, and 20.49%, with an average carbon content of 20.40%. The other portion was subjected to petrographic analysis.

[0025] Using the matching standard measuring spoon, mix the dust removal ash and embedding powder in a 1:1 volume ratio in a crucible, place the mixture in a melting vessel, heat and stir until it becomes viscous; quickly transfer the viscous sample to the mold of the molding machine and press it, remove it quickly after molding, let it stand for about 2 minutes, and mark the number on the side of the sample with a white marker. After the sample slide has cooled completely, grind it sequentially using 400-grit and 800-grit water-resistant sandpaper. Evenly sprinkle the coal and rock polishing agent onto the polishing cloth, ensuring the surface of the sample slide is horizontally in contact with the cloth. After polishing, the surface should have clear particles and be free of scratches, oil stains, water stains, or other residues. Depending on the sample's tilt, select an appropriate size of clay lump and place it on the glass slide. Place the sample on the clay lump and apply pressure for 3 seconds using a flattener to fully deform the clay and make the test surface parallel to the glass slide surface. Evenly coat the test surface of the sample with oil, minimizing air bubbles; generally, one drop is sufficient. Place the sample under a petrographic microscope and establish a 30x30 grid of dots on the sample surface. Based on the different characteristics of coal and coke under an optical microscope, specific details are as follows... Figure 1-7 As shown in the figure, the red circle represents coal and the blue circle represents coke. The number of coal and coke points falling on the carbonaceous phase was counted, and the proportion of coal and coke was calculated. The results are shown in Table 1.

[0026] Table 1. Analysis and Detection Records of Carbon Sources in Dust Collector Ash In summary, the total carbon content in the gravity dust collector ash from blast furnace No. 1, numbered 20250518-1Z, is 20.40%, of which coal accounts for 35.97% and coke accounts for 63.70%.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of analysing the carbon source in blast furnace dust, characterised in that, Comprise: Step 1: take the fly ash and mosaic powder into the crucible and mix well, place in the sample melter and stir while heating until sticky; Step 2: transfer the sticky sample in step 1 to the press molding machine and press to obtain thin press sheet; Step 3: after the thin press sheet cools down, polish the thin press sheet with sandpaper; Step 4: place the cement group with the same diameter as the thin press sheet on the glass slide after the press is unfolded; Step 5: place the thin press sheet on the top of the cement group and use the flattener to press so that the cement group is deformed and the top of the thin press sheet is parallel to the glass slide; Step 6: cover the cover glass on the top of the thin press sheet and observe with the petrographic microscope, count and calculate the proportion of coal and coke according to the morphological characteristics of coal and coke.

2. A method of analysing the carbon source in blast furnace dust according to claim 1, characterised in that, The mass ratio of fly ash and mosaic powder in step 1 is 1:

1.

3. A method of analysing carbon sources in blast furnace dust according to claim 1, characterised in that, The sandpaper in step 3 is 400 mesh and 800 mesh water-resistant sandpaper respectively.

4. The method of claim 1, wherein the carbon source in the blast furnace dust is analyzed. When observing to distinguish coal and coke in step 6, the judgment standard of coal is: irregular edges, damaged pores or pores filled with impurities.

5. The method of claim 1, wherein the carbon source in the blast furnace dust is analyzed. When observing to distinguish coal and coke in step 6, the judgment standard of coke is: porous fragment morphology or porous pore structure.

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