A sample preparation method for micro-area analysis of element occurrence state in hydrometallurgical slag

Abstract

The application discloses a sample preparation method for micro-area analysis of element occurrence state in wet metallurgy slag. Since the resolution of energy spectrum analysis is only 1-2 microns, if two particles are agglomerated together beyond the range, the energy spectrum point analysis will give the average information of the two particles, which is not conducive to the identification of the particles and the analysis of the spatial distribution of the elements. The application strengthens the dispersion of the particles by adding graphite to the metallurgy slag particle sample for grinding, ultrasonic oscillation, resin curing and the like. The addition of the graphite for grinding prevents agglomeration, so that the sample particles are fully dispersed, and the ultrasonic oscillation also strengthens the dispersion of the sample. After hydrolysis, 3-aminopropyltrimethoxysilane can be uniformly dispersed in the aqueous solution, the methoxy group can be well combined with the mineral metal, and the amino group can be well combined with the resin, so as to connect the metallurgy slag sample and the resin, so that the smallest metallurgy slag particle unit is uniformly embedded in the resin solid, and the sample process mineralogy analysis and subsequent resource comprehensive recycling are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and metallurgical engineering application technology, specifically relating to a method for preparing a sample for the process mineralogy testing of solid material particles during mineral processing. Background Technology

[0002] Hydrometallurgy includes process steps such as leaching, reduction and precipitation, solid-liquid separation, solvent extraction and ion exchange. Among these, precipitation reaction is one of the main technical means used for solution purification and separation.

[0003] In the mineralogy testing of mineral samples, the degree of dispersion of fine mineral particles directly affects the accuracy of data on mineral sample composition and distribution. Fine mineral particles are difficult to disperse completely during conventional resin curing, resulting in agglomeration. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are the main techniques for micro-area analysis of the elemental occurrence state in ores and smelting slags. However, due to the spatial resolution limitations of EDS, the characteristic X-rays excited from the material originate from a volume range of a few micrometers. Although the excitation region of characteristic X-rays can be reduced by decreasing the accelerating voltage, heavy metal atoms with higher atomic numbers still have a relatively large excitation region. On the other hand, precipitated slag particles are extremely fine, typically only a few micrometers or even submicrometers. During sampling and sample preparation, different types of particles agglomerate with each other, posing difficulties for micro-area analysis. The same beam of excited characteristic X-rays may originate from adjacent different particles.

[0004] Silane coupling agents have the ability to combine with both inorganic and organic materials, and can modify the surface of smelting slag, transforming the hydrophilic surface into an organic-friendly surface. This not only improves the wettability of smelting slag in epoxy resin, but also prevents particle agglomeration, so that the smallest particle unit of the smelting slag sample forms a uniform embedding after the epoxy resin is cured. This is beneficial for identifying the elemental information of individual particles and judging the dependency relationship. Summary of the Invention

[0005] The purpose of this invention is to provide a sample preparation method for micro-area analysis of the elemental occurrence state in hydrometallurgical slag. Utilizing the binding properties of silane coupling agents on slag particles and resin, the smallest particle units of the slag sample are uniformly embedded in the curing agent, thereby identifying the independent information of the particles and the dependencies between different elements. This invention solves the problem of difficult detection and analysis of extremely fine particle samples in hydrometallurgical slag due to particle agglomeration and uneven dispersion during process mineralogical analysis, providing a new approach for the preparation of solid particle samples for process mineralogical analysis in beneficiation processes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A sample preparation method for micro-area analysis of element occurrence state in hydrometallurgical slag: First, the solid particles of smelting slag are mixed and ground with graphite. Then, the ground particles are thoroughly mixed with hydrolyzed silane coupling agent, washed, and then uniformly embedded in resin to fully disperse the particles for easy analysis and detection.

[0008] Includes the following steps:

[0009] (1) Take a small amount of smelting slag sample and grind and sieve it.

[0010] (2) Take the sample from step (1), add graphite powder with a volume of 3-5 times that of the smelting slag sample, then add ethanol to cover the sample, mix and grind, and then ultrasonically disperse.

[0011] (3) Mix the silane coupling agent with a 95% ethanol solution and place it in a constant temperature water bath magnetic stirrer at 30-60℃.

[0012] (4) Add the smelting slag sample and graphite mixture from step (2) to the solution from step (3), stir at a constant temperature of 60-90℃, filter after reaction to obtain a slightly wet solid mixture, and wash away the residual silane coupling agent with ethanol.

[0013] (5) Take epoxy resin and curing agent in a mass ratio of 3:1, stir them evenly and pour them into a cube silicone mold. Then pour the solid obtained in step (4) into the mold so that it is evenly dispersed in the epoxy resin slurry.

[0014] (6) Place the mold from step (5) into a vacuum drying dish, vacuum the resin slurry to remove any remaining air bubbles, and then cure at room temperature for 24 hours.

[0015] (7) Demold the cured sample, use a handheld small cutter to cut the sample to obtain a longitudinal section, grind and polish the section, and wipe the polished surface clean with anhydrous ethanol.

[0016] (8) Place the sample from step (7) into a magnetron DC sputtering coating machine to sputter a layer of gold film. After taking it out, it can be placed in a scanning electron microscope for detection and analysis.

[0017] Furthermore, the silane coupling agent is 3-aminopropyltrimethoxysilane.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The present invention is based on the modification effect of silane coupling agent on the surface of smelting slag sample, which changes the surface of smelting slag particles from hydrophilic to organic, improves the wettability of smelting slag particles in resin, and makes the smallest particle unit of smelting slag sample uniformly embedded in curing agent, preventing particle agglomeration, which is beneficial to detection and analysis.

[0020] (2) This invention provides an efficient and convenient method for mining the elemental information contained among solid particles in hydrometallurgical slag during the metallurgical process, including elemental dependencies and spatial distribution patterns. It facilitates the exploration of elemental transformation and distribution patterns in processes such as leaching and precipitation, which is beneficial for process optimization. The detection method is universal, the test samples are diverse, and it can process solid materials generated in the metallurgical process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the interaction principle between silane coupling agents, epoxy resins, and smelting slag.

[0022] Figure 2 Scanning electron microscope (SEM) morphology analysis of zinc powder displacement slag;

[0023] Figure 3 SEM morphology analysis of zinc powder displacement slag embedded in resin;

[0024] Figure 4 Scanning electron microscope image of epoxy resin cured sample of pickling residue surface treated with silane coupling agent;

[0025] Figure 5 The relationship between Ga, Pb, Fe, and Al in zinc powder displacement slag samples. Detailed Implementation

[0026] This invention provides a sample preparation method for micro-area analysis of the element occurrence state in hydrometallurgical slag. To make the purpose, technical solution and effects of this invention clearer and more explicit, the invention will be further described in detail below, but this invention is not limited thereto.

[0027] Example 1

[0028] Before using the method described in this invention, in order to investigate the occurrence state and elemental distribution of gallium in the difficult-to-leach phase of zinc powder replacement slag and improve the gallium leaching rate, two methods were used to prepare process mineralogical samples of zinc powder replacement slag.

[0029] Method 1: Take a small amount of zinc powder replacement slag, grind and sieve it to obtain a test sample with a particle size of -200 mesh, coat the sample particles on the surface of conductive adhesive, then stick them on the test sample stage, put them into a magnetron DC sputtering coating machine to sputter a layer of gold film, and then take them out and put them into a scanning electron microscope for detection and analysis.

[0030] The morphological analysis results after scanning electron microscopy are as follows: Figure 2 As shown, it can be seen that agglomeration occurs between particle units, and due to the limitation of spatial resolution, it is difficult to obtain the elemental characteristics that reflect the individual particles in the particle group.

[0031] Method 2: Take a small amount of zinc powder replacement slag sample, grind and sieve it to obtain a test sample with a particle size of -200 mesh. Take 0.1g of the test sample, add 1g of 4000-mesh graphite powder and 50ml of ethanol, grind for 20 minutes, then ultrasonically disperse and filter to obtain a slightly moist solid mixture. Take 6g of epoxy resin, add 2g of curing agent, stir evenly and pour into a cube-shaped silicone mold. Then pour the slightly moist mixture into the mold, stir with a glass rod, and then use a handheld high-speed homogenizer to stir evenly so that the solid is uniformly dispersed in the epoxy resin.

[0032] The morphological analysis results after scanning electron microscopy are as follows: Figure 3 As shown, it can be seen that direct dispersion of particles in resin solids can achieve a certain dispersion effect, but particle units will still agglomerate, which is not conducive to the identification of single particles and the analysis of elemental spatial distribution.

[0033] Detailed description of the present invention:

[0034] (1) The zinc powder replacement slag in this example is obtained during the hydrometallurgical zinc purification process of sphalerite. It is a hydrometallurgical precipitation slag. The zinc powder replacement slag sample was ground and sieved to obtain a test sample with a particle size of -200 mesh.

[0035] (2) First, the zinc powder replacement residue was washed with dilute nitric acid at pH 1.0 at a liquid-to-solid ratio of 100:1 ml / g. After stirring for 2 hours, it was filtered using qualitative filter paper and a Buchner funnel. Then, it was slurried with deionized water and washed three times to remove soluble ions. The zinc powder replacement residue contains a large amount of copper-zinc hydrolysis products, including hydroxides and basic sulfates. These hydrolysis products are easily soluble in dilute acid, and target elements such as gallium are enriched in the acid-washed residue, which is beneficial for subsequent micro-area analysis. The purpose of using nitric acid is to prevent the leached lead from precipitating as lead sulfate in the residue, which would interfere with the analysis of the occurrence state of gallium and lead in the difficult-to-leach gallium-containing lead phase.

[0036] (3) Take 0.1g of the sample from step (2) and place it in an agate mortar. Add 1.0g of 4000-mesh graphite powder and 10ml of anhydrous ethanol. Grind for 20 minutes, then ultrasonically disperse for 1 hour. Filter the mixture to obtain replacement slag particles with a particle size of 1-2 micrometers. Grinding and ultrasonically treating the sample with graphite together can fully mix the replacement slag particles and graphite particles. The flake-like graphite fills the spaces between the replacement slag particles, preventing agglomeration and increasing the distance between the replacement slag particles to prevent mutual interference during energy dispersive spectroscopy analysis.

[0037] (4) Add 0.15 ml of 3-aminopropyltrimethoxysilane (APTMS) to 4.8 ml of 95% ethanol solution, and place the solution in a constant temperature water bath with a magnetic stirrer at 50°C for 30 minutes. 3-APTMS is an aminosilane with the molecular formula C6H. 17NO3Si, a silane coupling agent, can simultaneously bind to inorganic materials (such as glass, metals, or minerals) and organic materials (such as organic polymers, coatings, or adhesives), and is often used to improve the filler function of polymer materials. In this invention, it plays a role in modifying the surface of the displacement slag particles, allowing the epoxy resin to better wet the particles, preventing particle agglomeration, and ensuring that the smallest particle units of the sample are uniformly embedded in the resin.

[0038] (5) Add the displacement slag / graphite mixture prepared in step (3) to the solution prepared in step (4), place it in a constant temperature water bath magnetic stirrer, stir at 80°C for 6 hours, and filter to obtain a slightly moist mixture sample.

[0039] (6) Add 10 ml of anhydrous ethanol to the solid mixture obtained in step (5), mix and filter. After filtration, add ethanol to the Buchner funnel to wash and filter. Wash three times in total, each time using 10 ml of ethanol.

[0040] (7) Take 6g of epoxy resin, add 2g of curing agent, stir evenly and pour into the silicone mold. Then pour the slightly wet mixture prepared in step (6) into the mold. First stir with a glass rod, then use a homogenizer to homogenize for 10 minutes at a speed of 10000rpm / min so that the solid particles are evenly dispersed in the epoxy resin slurry.

[0041] (8) Place the mold from step (7) into a vacuum drying dish, vacuum it and let it stand for 30 minutes to remove any remaining air bubbles in the resin slurry. After removing it, cure it at room temperature for 24 hours.

[0042] (9) Demold the cured sample, use a handheld small cutter to cut the sample to obtain a longitudinal section, and polish the section with 500 grit, 800 grit, 1000 grit, 1500 grit and 2000 grit sandpaper in sequence, then polish with a cloth, and wipe the polished surface clean with anhydrous ethanol.

[0043] (10) Place the sample from step (9) into a magnetron DC sputtering coating machine to sputter a layer of gold film. After taking it out, it can be placed in a scanning electron microscope for detection and analysis.

[0044] The morphology of the sample being tested is as follows Figure 4 As shown, the zinc powder replacement slag particles after pickling exhibited good dispersion with no agglomeration. Each dispersed particle independently provided elemental information. Partial results of energy dispersive spectroscopy (EDS) analysis of this image are shown in Table 1. Regression analysis of the Ga content with Pb, Fe, and Al content revealed a linear correlation between Ga and Pb / Fe contents in the pickling slag. The functional relationship between Ga and Pb was: Y = 0.27X + 4.933, R0 2= The functional relationship between Ga and Fe is: Y = 0.494X + 0.084, R2 =0.554. The linear correlation between Ga and Al is weak. The sample preparation method provided by this invention for micro-area analysis of element occurrence state in hydrometallurgical slag greatly improves the dispersibility of mineral sample particles, which is beneficial for studying the elemental dependence and spatial distribution of mineral samples.

[0045] Table 1. Energy dispersive spectroscopy (EDS) results of aluminum, iron, gallium, and lead in epoxy resin-cured samples of pickling residue treated with silane coupling agent.

[0046]

[0047] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A sample preparation method for micro-area analysis of element occurrence states in hydrometallurgical slag, characterized in that: First, graphite is added to ethanol to initially grind and disperse the smelting slag particles. Then, a silane coupling agent is used to ensure that the smallest unit particles of the smelting slag are uniformly dispersed and embedded in the resin. Finally, the cured sample is subjected to process mineralogical testing and analysis to clarify the elemental distribution rules and particle morphology. The process includes the following steps: (1) Take a small amount of wet smelting slag and grind and sieve it; (2) Take the sample from step (1), wash the smelting slag with dilute nitric acid at pH 1.0, with a liquid-to-solid ratio of 100:1 ml / g, stir for 2 hours, filter with qualitative filter paper and Buchner funnel, then slurry with deionized water, and wash three times with water to remove soluble ions. (3) Take 0.1g of the sample from step (2) and put it into an agate mortar. Add 1.0g of 4000-mesh graphite powder and 10ml of anhydrous ethanol. Grind for 20 minutes, ultrasonically disperse for 1 hour, and then filter to obtain replacement residue particles with a particle size of 1~2 micrometers. (4) Mix the silane coupling agent with a 95% ethanol solution and place it in a constant temperature water bath magnetic stirrer at 30-60℃. (5) Add the smelting slag and graphite mixture from step (3) to the solution from step (4), stir at a constant temperature of 60-90℃, filter after reaction to obtain a slightly wet solid mixture, and wash away the residual silane coupling agent with ethanol. (6) Take epoxy resin and curing agent in a mass ratio of 3:1, stir evenly and pour into a cube silicone mold, then pour the solid obtained in step (5) into the mold, stir with a glass rod first, then use a homogenizer to homogenize for 10 minutes at a speed of 10000 rpm / min, so that the solid particles are evenly dispersed in the epoxy resin slurry. (7) Place the mold from step (6) into a vacuum drying dish, vacuum and let it stand for 30 minutes to remove any remaining air bubbles in the resin slurry, then remove it and cure it at room temperature for 24 hours. (8) Demold the cured sample, use a handheld small cutter to cut the sample to obtain a longitudinal section, and polish the section with 500 grit, 800 grit, 1000 grit, 1500 grit and 2000 grit sandpaper in sequence, then polish with a cloth, and wipe the polished surface clean with anhydrous ethanol. (9) Place the sample from step (8) into a magnetron DC sputtering coating machine to sputter a layer of gold film, and then take it out and place it in a scanning electron microscope for detection and analysis.

2. The method according to claim 1, characterized in that: The silane coupling agent is 3-aminopropyltrimethoxysilane.

3. The method according to claim 1, characterized in that: The mass ratio of hydrometallurgical slag to epoxy resin is 1:60.

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