Method for measuring quality and content of plastic-sealed gold product

Abstract

The present application relates to the technical field of chemical detection, and particularly relates to a method for measuring the quality and content of plastic-wrapped gold products, comprising the following steps: S1, placing the plastic-wrapped gold product to be detected into DMF, heating to above 150 DEG C, heating for 10-15 min, taking out, tearing off the surface plastic wrapping, and obtaining a gold product containing gum; S2, performing oxidation cupellation treatment on the gold product containing gum to remove the surface gum part, and obtaining a treated gold product; S3, weighing the gold mass in the treated gold product, and detecting the gold content in the treated gold product by using fire assaying method. The present application can effectively remove various types of plastic wrapping materials and gum through the combined application of DMF preliminary treatment, composite sol agent pretreatment, multi-stage oxidation cupellation and fire assaying method, while maximizing the protection of the gold product itself, and significantly improving the efficiency and precision of the quality and content measurement of the plastic-wrapped gold product.

Description

Technical Field

[0001] This invention relates to the field of chemical testing technology, and in particular to a method for determining the quality and content of plastic-sealed gold products. Background Technology

[0002] Gold products are often laminated, a process that involves using a laminating machine to tightly seal the gold product in a plastic film after high-temperature treatment, such as gold foil and commemorative banknotes. This lamination process ensures a strong seal, preventing dust and other contaminants from penetrating and protecting the precious metal from external environmental influences, making it highly effective in protecting precious metal products. However, this also presents another problem: once the seal is intact, it is extremely difficult to open. In actual testing, there are no specialized tools or effective sample handling methods available for such samples.

[0003] In the testing of gold-coated flake products, gold content and quality are key concerns for both manufacturers and consumers. Currently, the industry commonly uses strong acids or alkalis to soften the colloid, or employs a burning method. Using strong acids or alkalis to remove the colloid requires the coated gold flake to be completely immersed in the solution. This can cause impurities in the gold layer, such as iron, zinc, aluminum, and copper, to react with the acid or alkali, destroying the impurity content and leading to inaccurate gold content tests. The burning method, when using very thin gold flakes, may melt them, or the colloid may not burn completely, preventing the formation of a complete gold layer for subsequent quality and gold content measurements. Furthermore, the burning method, which involves burning the polymer coating, is neither environmentally friendly nor has many other drawbacks.

[0004] Existing patent CN201610332962.6 discloses a rapid method for determining the gold content and quality of surface-coated gold sheets. This method involves pre-treating the surface-coated gold sheet with a sol-gel agent, followed by X-ray fluorescence spectroscopy for gold content detection. The sol-gel pre-treatment step targets only the colloidal reaction on the film, without reacting with the gold layer. This not only allows for rapid and convenient separation of the film from the gold layer but also largely preserves the integrity of the gold layer. The decoated gold sheet can then be easily subjected to X-ray fluorescence spectroscopy for accurate gold quality determination. The above-mentioned technical solution mainly involves sol-gel treatment followed by cleaning to peel off the coating layer from the surface-coated gold sheet. However, this method still has the following problems: First, using a single or simple combination of organic solvents as a sol agent for demolding results in limited sol-gel effectiveness, making it unsuitable for all types of molding materials, especially for complex or difficult-to-process molding materials. Second, directly peeling off the coating layer after sol-gel treatment may leave adhesive residue on the gold sheet surface, affecting the test results. Furthermore, the sol-gel treatment takes 1-2 hours, which is too long and significantly reduces the efficiency of sample processing. In cases requiring analysis of a large number of samples, this will greatly prolong the entire testing process and reduce the efficiency of quality inspection. Summary of the Invention

[0005] In view of this, the present invention proposes a method for determining the quality and content of plastic-sealed gold products, in order to solve the problem that the surface plastic film and adhesive residue are not completely removed in the existing detection of plastic-sealed gold products, thus affecting the accuracy of the detection of the quality and content of plastic-sealed gold products.

[0006] The technical solution of this invention is achieved as follows: This invention provides a method for determining the quality and content of plastic-sealed gold products, comprising the following steps: S1. Place the plastic-sealed gold product to be tested into DMF, heat it to above 150℃, heat for 10-15 minutes, take it out, peel off the surface plastic seal, and obtain the gold product containing adhesive. S2. The gold product containing adhesive is subjected to anodizing and blowing treatment to remove the adhesive on the surface, resulting in the treated gold product. S3. Weigh the gold content in the treated gold product and use the fire assay method to detect the gold content in the treated gold product.

[0007] In this invention, firstly, high-temperature DMF treatment (above 150°C) efficiently removes the molding compound layer, applicable to various types of molding materials. Secondly, a combination of composite sol pretreatment and oxidation blowing treatment thoroughly removes surface adhesive, ensuring sample purity. Fire assay is used for precise determination, which may be more suitable for determining high-purity gold compared to X-ray fluorescence spectroscopy. Through DMF high-temperature treatment, composite sol pretreatment, and oxidation blowing treatment, impurities are removed while maximizing the retention of the metal itself, minimizing sample loss. By combining efficient demolding, thorough impurity removal, and precise measurement techniques, a comprehensive, accurate, and widely applicable method for determining the quality and content of molded gold products is provided, meeting the determination needs of various types of molded gold products.

[0008] Based on the above technical solutions, preferably, step S1 specifically includes: cutting off the edges of the plastic-sealed gold product to be tested to expose the main body of the plastic seal, then cutting it into multiple segments and placing them in DMF, heating it to above 150°C until it is slightly boiling, and then continuing to heat it for 10-15 minutes until the plastic seal and the adhesive part soften, taking it out, peeling off the surface plastic seal, and obtaining the gold product containing adhesive.

[0009] Specifically, cutting the gold-encapsulated product to be tested into multiple segments increases the surface area, allowing DMF to make more thorough contact with the encapsulating material and accelerating the dissolution process. DMF, as a solvent, has strong dissolving power, especially for polymer materials. Raising the temperature to above 150°C to near boiling point utilizes DMF's high boiling point, further enhancing its dissolving ability at high temperatures, allowing for faster and more effective softening and dissolution of the encapsulating layer. This method is more efficient than traditional single-solvent treatment at room temperature, capable of handling various types of encapsulating materials, including some difficult-to-remove layers. Simultaneously, since DMF has almost no effect on metallic gold, it maximizes the protection of the gold product itself, minimizing sample loss and laying the foundation for subsequent deep cleaning and accurate measurement, thus improving the efficiency and accuracy of the entire measurement process.

[0010] Based on the above technical solutions, preferably, in step S2, before the gold product containing adhesive is subjected to oxidation and ash blowing treatment, the gold product containing adhesive is further subjected to pretreatment in a composite sol.

[0011] Based on the above technical solutions, preferably, the pretreatment includes: placing the gold product containing adhesive into a composite sol, ultrasonically stirring at room temperature for 10-15 minutes, removing the gold product, washing it sequentially with anhydrous ethanol and deionized water, and vacuum drying it to obtain the pretreated gold product.

[0012] Pretreatment with a composite sol before the oxidation ash blowing process further removes residual molding materials and adhesives. Utilizing the strong dissolving power and versatility of the composite sol, the residues are softened and dissolved under relatively mild conditions (55-65℃). This pretreatment can remove stubborn residues that may still remain after DMF high-temperature treatment, reduce the burden on the oxidation ash blowing process, improve its efficiency, and may also reduce the potential impact of high-temperature treatment on the gold products themselves.

[0013] Based on the above technical solutions, preferably, the composite sol agent comprises the following components by mass: 60-80 parts of mixed solvent, 4-6 parts of polyethylene glycol monolaurate, 2-4 parts of copper chloride, 1-1.5 parts of ascorbic acid, 1-2 parts of polyvinyl alcohol, and 2-4 parts of citric acid.

[0014] Based on the above technical solutions, preferably, the mixed solvent, by mass parts, includes the following components: 40-50 parts DMF, 10-13 parts acetone, 8-12 parts γ-butyrolactone, and 2-5 parts toluene.

[0015] Based on the above technical solutions, preferably, the preparation method of the composite sol includes: stirring and mixing DMF, acetone and γ-butyrolactone evenly, then sequentially adding toluene, polyethylene glycol monolaurate, copper chloride, ascorbic acid, polyvinyl alcohol and citric acid, and stirring continuously at room temperature for 30-60 min to obtain the composite sol.

[0016] Specifically, in the composite solvent, DMF effectively softens and dissolves various molding compounds, serving as the core component of the entire solvent system; acetone possesses excellent permeability and rapid evaporation characteristics, accelerating the dissolution process and improving solution fluidity; γ-butyrolactone enhances the stability and durability of the solution while also exhibiting good dissolving power; toluene, as a non-polar solvent, is suitable for dissolving certain hydrophobic plastics and adhesives, compensating for the shortcomings of other polar solvents; polyethylene glycol monolaurate significantly reduces the surface tension of the solution, promoting full contact between the solvent and the molding compound, thereby improving dissolution efficiency; copper chloride and ascorbic acid form a controllable redox system, generating a mild and continuous redox environment that helps break certain chemical bonds in the molding compound and adhesives, accelerating their decomposition process; polyvinyl alcohol can form a protective film during the dissolution process, preventing excessive corrosion of the gold product surface and also contributing to the stability of the entire solution system; citric acid may act as a chelating agent, helping to remove oxides or other impurities from the metal surface and improving cleaning effectiveness. The synergistic effect among the above components enables this composite sol to efficiently soften and remove various types of molding compounds and adhesives, while maximizing the protection of the gold products themselves.

[0017] Based on the above technical solutions, preferably, the oxidation blowing includes: placing the pretreated gold product into a muffle furnace, heating it to 275-325℃ and holding it for 5-10 min, then heating it to 475-525℃ and holding it for 5-10 min, and finally heating it to 550-650℃ and holding it for 5-10 min.

[0018] Specifically, the process involves holding the gold at 275-325℃ for 5-10 minutes. The lower temperature allows for the initial oxidation and decomposition of residual organic matter while preventing excessive oxidation of the metal. Subsequently, the temperature is increased to 475-525℃ and held for 5-10 minutes. This intermediate temperature range further oxidizes and removes more stubborn organic residues while initiating the decomposition of some complex inorganic compounds. Finally, a high-temperature stage at 550-650℃ for 5-10 minutes completely oxidizes and removes almost all impurities, including some difficult-to-remove metal oxides. The entire process utilizes the different thermal behaviors of the material at different temperatures. By gradually increasing the temperature and precisely controlling the time, the process ensures thorough removal of impurities while maximizing the protection of the gold itself. This method not only effectively removes trace impurities that may remain after composite sol pretreatment but also removes the oxide layer on the gold surface, resulting in high-purity gold samples and providing a reliable basis for subsequent content determination.

[0019] Based on the above technical solutions, preferably, the fire assay method includes: mixing the treated gold product with silver granules, then wrapping it with lead foil, blowing it with oxide ash for 15-25 minutes; after crushing and annealing, rolling it into a thin sheet with a thickness of 0.15-0.20 mm, and then performing gold separation treatment on the thin sheet.

[0020] Based on the above technical solutions, preferably, the mass ratio of the processed gold product, silver granules and lead foil is 1:2.1-2.5:4, and the temperature of the oxide ash blowing is 900-950℃.

[0021] Based on the above technical solutions, preferably, the gold separation process includes: placing the sheet in a nitric acid solution, heating to 90-95℃, performing the gold separation process for 25-35 minutes, washing and drying; placing the sheet in a nitric acid solution, heating to 100-120℃, performing the gold separation process for 25-35 minutes, washing and drying, weighing and calculating to obtain the gold content of the plastic-sealed gold product.

[0022] Specifically, the fire assay method is used to detect the gold content of gold products. The high-temperature molten lead has a great ability to capture gold, silver and other precious metals. It can completely dissolve the gold and silver exposed in the molten state into the lead. Since the specific gravity of lead is different from that of slag, the lead sinks to form a lead buckle while the slag floats on top, thus separating the lead buckle from the slag. The gold and silver are separated by taking advantage of the different solubility of gold and silver in nitric acid. The silver forms silver nitrate and enters the solution, and the remaining gold is weighed and its content is calculated.

[0023] The method for determining the quality and content of plastic-sealed gold products according to the present invention has the following advantages over the prior art: (1) The DMF preliminary treatment is carried out at high temperature, which can effectively soften and dissolve most of the plastic sealing materials, so that the surface plastic sealing can be easily removed; the composite sol pretreatment is carried out under relatively mild conditions, and its multi-component system is used to further soften and dissolve the plastic sealing materials and adhesives remaining after DMF treatment; the multi-stage oxidation ash blowing treatment gradually oxidizes and removes impurities that cannot be completely removed in the first two steps through temperature gradient, including some inorganic compounds and metal oxides that are difficult to remove; through the combined application of DMF preliminary treatment, composite sol pretreatment, multi-stage oxidation ash blowing and fire assay, the comprehensive cleaning and accurate determination of plastic-sealed gold products are achieved. Compared with the existing technology, the sol treatment time is greatly shortened, and various types of plastic sealing materials and adhesives can be effectively removed, maximizing the protection of the gold products themselves, and significantly improving the efficiency and accuracy of the determination of the quality and content of plastic-sealed gold products. (2) The composite sol contains a mixed solvent, surfactant, redox system, protectant and chelating agent. The multi-component synergistic effect, under relatively mild conditions (55-65℃) and combined with ultrasonic stirring, can soften and dissolve stubborn residues, creating better conditions for subsequent oxidation and ash blowing treatment, and improving the accuracy of the test results. The multi-stage oxidation and ash blowing treatment achieves deep cleaning and purification of the pretreated gold products through temperature gradient control. From the initial oxidation and decomposition of organic matter to the complete removal of stubborn impurities, this gradual temperature control can not only effectively remove various types of impurities, including complex inorganic compounds and metal oxides, but also protect the gold itself from excessive oxidation to the maximum extent, and obtain high-purity gold samples, further improving the accuracy and reliability of the test results. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of the method for determining the quality and content of plastic-sealed gold products according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 This embodiment provides a method for determining the quality and content of plastic-sealed gold products, such as... Figure 1 As shown, the specific steps include: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100 mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the temperature above 150℃ until it gently boils. Hold for 12 minutes, until the plastic seal and the adhesive portion soften. Remove the sample, peel off the surface plastic seal, and obtain the gold product containing the adhesive. S2. Mix 45g DMF, 12g acetone, and 10g γ-butyrolactone evenly. Then, add 3g toluene, 5g polyethylene glycol monolaurate, 3g copper chloride, 1.2g ascorbic acid, 1.5g polyvinyl alcohol, and 3g citric acid sequentially. Stir continuously at room temperature for 45 minutes to obtain a composite sol. Place 1g of the gold product containing the sol into 10g of the composite sol and sonicate at room temperature for 12 minutes. Remove the gold product and wash it sequentially with anhydrous ethanol and deionized water, then vacuum dry it to obtain the pretreated gold product. Select a suitable porcelain crucible (30 mL), place the pretreated gold product inside, and perform oxidation blowing to remove the surface adhesive. Place the crucible in a muffle furnace, open the furnace door, and heat to 300℃ for 8 minutes. Then, heat to 500℃ for 8 minutes, and finally heat to 600℃ for 8 minutes. Remove the treated gold product, cool it to room temperature, and weigh the net gold. S3. Weigh 1g of the treated gold product, add 2.3g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 20 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.18 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in 93℃ nitric acid (1+1) for gold separation for 30 minutes, wash it 3 times, then place it in 110℃ nitric acid (2+1) for a second gold separation of 30 minutes, wash it 3 times, dry and cool it, and then weigh and calculate the gold content.

[0028] Example 2 This embodiment provides a method for determining the quality and content of plastic-sealed gold products, specifically including the following steps: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100 mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the temperature above 150℃ until it gently boils. Hold for 10 minutes until the plastic seal and the adhesive part soften. Remove the sample, peel off the surface plastic seal, and you will obtain the gold product containing the adhesive. S2. Mix 40g DMF, 10g acetone, and 8g γ-butyrolactone evenly. Then, add 2g toluene, 4g polyethylene glycol monolaurate, 2g copper chloride, 1g ascorbic acid, 1g polyvinyl alcohol, and 2g citric acid in sequence. Stir continuously at room temperature for 30 minutes to obtain a composite sol. Place 1g of the gold product containing the colloid into 10g of the composite sol and sonicate at room temperature for 10 minutes. Remove the gold product and wash it with anhydrous ethanol and deionized water in sequence, and then vacuum dry it to obtain the pretreated gold product. Select a suitable porcelain crucible (30 mL), place the pretreated gold product inside, and perform oxidation blowing to remove the surface adhesive. Place it in a muffle furnace, open the furnace door, and heat to 275℃ for 10 minutes. Then, heat to 475℃ for 10 minutes, and finally heat to 550℃ for 10 minutes. Remove the treated gold product, cool it to room temperature, and weigh the net gold. S3. Weigh 1g of the treated gold product, add 2.1g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 15 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.15 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in 90℃ nitric acid (1+1) for gold separation for 35 minutes, wash it 3 times, then place it in 100℃ nitric acid (2+1) for a second gold separation of 35 minutes, wash it 3 times, dry and cool it, then weigh and calculate the gold content. Example 3 This embodiment provides a method for determining the quality and content of plastic-sealed gold products, specifically including the following steps: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100 mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the temperature above 150℃ until it gently boils. Hold for 15 minutes, until the plastic seal and the adhesive portion soften. Remove the sample, peel off the surface plastic seal, and obtain the gold product containing the adhesive. S2. Mix 50g DMF, 13g acetone, and 12g γ-butyrolactone evenly. Then, add 5g toluene, 6g polyethylene glycol monolaurate, 4g copper chloride, 1.5g ascorbic acid, 2g polyvinyl alcohol, and 4g citric acid in sequence. Stir continuously at room temperature for 60 minutes to obtain a composite sol. Place 1g of the gold product containing the sol into 10g of the composite sol and sonicate at room temperature for 15 minutes. Remove the gold product and wash it with anhydrous ethanol and deionized water in sequence, and then vacuum dry it to obtain the pretreated gold product. Select a suitable porcelain crucible (30 mL), place the pretreated gold product inside, and perform oxidation blowing to remove the surface adhesive. Place the crucible in a muffle furnace, open the furnace door, and heat to 325℃ for 5 minutes. Then, heat to 525℃ for 5 minutes, and finally heat to 650℃ for 5 minutes. Remove the treated gold product, cool it to room temperature, and weigh the net gold. S3. Weigh 1g of the treated gold product, add 2.5g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 25 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.20 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in 95℃ nitric acid (1+1) for gold separation for 25 minutes, wash it 3 times, then place it in 120℃ nitric acid (2+1) for a second gold separation of 25 minutes, wash it 3 times, dry and cool it, weigh and calculate the gold content. Example 4 This embodiment provides a method for determining the quality and content of plastic-sealed gold products, specifically including the following steps: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100 mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the temperature above 150 degrees Celsius until it gently boils. Maintain this temperature for 13 minutes until the plastic seal and the adhesive portion soften. Remove the sample, peel off the surface plastic seal, and you will obtain the gold product containing the adhesive. S2. Mix 48g DMF, 11g acetone, and 9g γ-butyrolactone evenly. Then, add 4g toluene, 4.5g polyethylene glycol monolaurate, 2.5g copper chloride, 1.3g ascorbic acid, 1.8g polyvinyl alcohol, and 2.5g citric acid sequentially. Stir continuously at room temperature for 40 minutes to obtain a composite sol. Place 1g of the gold product containing the sol into 10g of the composite sol and sonicate at room temperature for 13 minutes. Remove the gold product and wash it sequentially with anhydrous ethanol and deionized water, then vacuum dry to obtain the pretreated gold product. Select a suitable porcelain crucible (30 mL), place the pretreated gold product inside, and perform oxidation blowing to remove the surface adhesive. Place the crucible in a muffle furnace, open the furnace door, and heat to 310℃ for 6 minutes. Then, heat to 510℃ for 7 minutes, and finally heat to 620℃ for 6 minutes. Remove the treated gold product, cool it to room temperature, and weigh the net gold. S3. Weigh 1g of the treated gold product, add 2.2g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 18 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.16 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in nitric acid (1+1) at 92℃ for 32 minutes for gold separation, wash it 3 times, then place it in nitric acid (2+1) at 115℃ for a second gold separation of 28 minutes, wash it 3 times, dry and cool it, and then weigh and calculate the gold content.

[0029] Comparative Example 1 This comparative example provides a method for determining the quality and content of plastic-sealed gold products, specifically including the following steps: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100 mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the temperature above 150℃ until it just begins to boil. Hold for 12 minutes, until the plastic seal and the adhesive portion soften. Remove the sample, peel off the surface plastic seal, and you will obtain the gold product containing the adhesive. S2. Mix 45g of DMF and 12g of acetone evenly to obtain a mixed sol. Place 1g of gold product containing adhesive into 10g of mixed sol and ultrasonically stir at room temperature for 12 minutes. Take out the gold product and wash it with anhydrous ethanol and deionized water in sequence, and then vacuum dry it to obtain the pretreated gold product. Select a suitable porcelain crucible (30 mL), place the pretreated gold product inside, and perform oxidation blowing to remove the surface adhesive. Place the crucible in a muffle furnace, open the furnace door, and heat to 300℃ for 8 minutes. Then, heat to 500℃ for 8 minutes, and finally heat to 600℃ for 8 minutes. Remove the treated gold product, cool it to room temperature, and weigh the net gold. S3. Weigh 1g of the treated gold product, add 2.3g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 20 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.18 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in nitric acid (1+1) at 93℃ for 30 minutes for gold separation, wash it 3 times, then place it in nitric acid (2+1) at 110℃ for a second 30-minute gold separation, wash it 3 times, dry and cool it, then weigh and calculate the gold content.

[0030] Comparative Example 2 This comparative example provides a method for determining the quality and content of plastic-sealed gold products, specifically including the following steps: S1. Trim the edges of 1g of the sample to be tested to expose the main body of the plastic seal. Add 100mL of N,N-dimethylformamide (DMF) to a beaker. Depending on the liquid level in the beaker, cut the sample into multiple pieces and place them in the beaker, immersing the sample in the DMF. Cover with a watch glass and heat with a hot plate, maintaining the heating temperature above 150℃ until it gently boils. Maintain this temperature for 12 minutes until the plastic seal and the adhesive portion soften. Remove the sample, peel off the surface plastic seal, and you will obtain the gold product containing the adhesive. S2. Mix 45g DMF, 12g acetone, and 10g γ-butyrolactone evenly. Then, add 3g toluene, 5g polyethylene glycol monolaurate, 3g copper chloride, 1.2g ascorbic acid, 1.5g polyvinyl alcohol, and 3g citric acid sequentially. Stir continuously at room temperature for 45 minutes to obtain a composite sol. Place 1g of the gold product containing the sol into 10g of the composite sol and sonicate at room temperature for 12 minutes. Remove the gold product and wash it sequentially with anhydrous ethanol and deionized water, then vacuum dry it to obtain the pretreated gold product. S3. Weigh 1g of pretreated gold product, add 2.3g of high-purity silver granules, place it in 4g of lead foil, wrap it up, and put it in a ash-blowing furnace for 20 minutes of oxidation ash blowing, followed by air cooling. After crushing and annealing, roll it into a thin sheet about 0.18 mm thick. After annealing, roll it into a cylindrical shape and place it in a gold separation basket. Place it in 93℃ nitric acid (1+1) for gold separation for 30 minutes, wash it 3 times, then place it in 110℃ nitric acid (2+1) for a second gold separation of 30 minutes, wash it 3 times, dry and cool it, weigh the gold roll, and calculate the gold content.

[0031] The effectiveness of this embodiment will be further explained below with reference to the test results.

[0032] The mass and content of the gold products in the examples and comparative examples before and after sol-gel treatment (i.e., the gold products before sol-gel treatment) were tested, and the sol-gel treatment time (including the time for removing the sol-gel film and surface adhesive) was recorded. The results are shown in Table 1.

[0033] Table 1. Quality and Content of Gold Products As shown in Table 1, after the sol-gel decoction of the present invention, the gold quality and content of the gold products are not significantly different from those before plastic sealing, and fully meet the testing requirements. Moreover, compared with the prior art, the preparation method provided by the present invention can control the sol treatment time to within 1 hour, which can shorten the sol treatment time while ensuring that the gold quality and content of the gold products after sol treatment are not significantly different from those before plastic sealing.

[0034] 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 for determining the quality and content of plastic-sealed gold products, characterized in that: Includes the following steps: S1. Place the plastic-sealed gold product to be tested into N,N-dimethylformamide, heat it to above 150°C, heat it for 10-15 minutes, take it out, peel off the surface plastic seal, and obtain the gold product containing adhesive. S2. The gold product containing adhesive is subjected to anodizing and blowing treatment to remove the adhesive on the surface, resulting in the treated gold product. S3. Weigh the gold content in the treated gold product and use the fire assay method to test the gold content in the treated gold product. In step S2, before the gold product containing adhesive is subjected to oxidation and blowing treatment, the process further includes: pre-treating the gold product containing adhesive in a composite sol, wherein the composite sol comprises the following components by mass: 60-80 parts of mixed solvent, 4-6 parts of polyethylene glycol monolaurate, 2-4 parts of copper chloride, 1-1.5 parts of ascorbic acid, 1-2 parts of polyvinyl alcohol, and 2-4 parts of citric acid. The mixed solvent, by mass parts, comprises the following components: 40-50 parts of N,N-dimethylformamide, 10-13 parts of acetone, 8-12 parts of γ-butyrolactone, and 2-5 parts of toluene; The preparation method of the composite sol includes: stirring N,N-dimethylformamide, acetone and γ-butyrolactone until uniform, then adding toluene, polyethylene glycol monolaurate, copper chloride, ascorbic acid, polyvinyl alcohol and citric acid in sequence, and stirring continuously at room temperature for 30-60 min to obtain the composite sol.

2. The method for determining the quality and content of plastic-sealed gold products as described in claim 1, characterized in that: The pretreatment includes: placing the gold product containing the adhesive into a composite sol, ultrasonically stirring at room temperature for 10-15 minutes, removing the gold product, washing it sequentially with anhydrous ethanol and deionized water, and vacuum drying it to obtain the pretreated gold product.

3. The method for determining the quality and content of plastic-sealed gold products as described in claim 2, characterized in that: The oxidation blowing process includes: placing the pretreated gold product into a muffle furnace, heating it to 275-325℃ and holding it for 5-10 minutes, then heating it to 475-525℃ and holding it for 5-10 minutes, and finally heating it to 550-650℃ and holding it for 5-10 minutes.

4. The method for determining the quality and content of plastic-sealed gold products as described in claim 1, characterized in that: The fire assay method includes: mixing the treated gold product with silver granules, then wrapping it with lead foil, blowing it with oxide ash for 15-25 minutes; after crushing and annealing, rolling it into a thin sheet with a thickness of 0.15-0.20 mm, and then performing gold separation treatment on the thin sheet.

5. The method for determining the quality and content of plastic-sealed gold products as described in claim 4, characterized in that: The mass ratio of the processed gold product, silver granules, and lead foil is 1:2.1-2.5:4, and the temperature of the oxide ash blowing in the fire assay is 900-950℃.

6. The method for determining the quality and content of plastic-sealed gold products as described in claim 4, characterized in that: The gold separation process includes: placing the sheet in a nitric acid solution, heating to 90-95℃, performing the gold separation process for 25-35 minutes, washing and drying; then placing the sheet in a nitric acid solution, heating to 100-120℃, performing the gold separation process for 25-35 minutes, washing and drying, weighing and calculating to obtain the gold content of the plastic-sealed gold product.

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