A method for simultaneous determination of gold and silver in smelting fumes

Abstract

The application provides a method for jointly measuring gold and silver in smelting fumes, which adopts a fire assaying method to enrich gold and silver in the sample, and a large part of silver in the obtained gold-silver combined particle is dissolved by using a nitric acid solution, after filtration, gold in the filter residue is dissolved by using aqua regia, after silver chloride is precipitated and separated from gold and silver again, the remaining small amount of silver in the filter residue is dissolved, the segmented digestion method prevents "passivation" of silver in the combined particle when the aqua regia directly dissolves the silver, and ensures that the gold and silver in the combined particle are completely dissolved into the solution, and then atomic absorption spectrometry is adopted to jointly measure the gold and silver, compared with the existing gold-silver separate measurement method of measuring gold by the fire assaying method and measuring silver by the atomic absorption spectrometry, the detection process is shortened and the detection efficiency is improved, and therefore the method has a certain application prospect.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing technology, specifically relating to a method for the joint detection of gold and silver in smelting flue dust. Background Technology

[0002] Smelting fumes are aerosol particles generated through physical / chemical reactions during high-temperature smelting, refining, and casting processes of metal raw materials. Their composition is complex, containing various valuable metals such as gold, silver, copper, lead, and zinc, as well as their oxides. Accurate determination of the metal element content in smelting fumes is crucial for optimizing process flows and calculating metal balance. The detection of precious metals such as gold and silver is a core aspect of resource recovery and quality control.

[0003] Current methods for detecting gold and silver in smelting dust involve analyzing each metal separately, which has significant limitations. Gold detection primarily uses the fire assay method, but due to the large number of impurities in smelting dust, the gold particles obtained after enrichment using the fire assay are easily pulverized when separated with nitric acid solution, making gravimetric analysis impossible. Existing methods include: first, lead coating and secondary ash blowing of the particles to remove impurities again, followed by gravimetric determination of gold. However, this method cannot accurately calculate silver loss and cannot achieve co-analysis of gold and silver. Second, dissolving the particles and using atomic absorption spectrometry to determine gold. Currently, this method directly measures the supernatant containing silver chloride precipitate, also failing to achieve co-analysis of gold and silver. Silver detection primarily uses atomic absorption spectrometry, but due to the small sample size (typically 0.2g–0.5g) and the complex and homogeneous composition of smelting dust, the results of atomic absorption spectrometry for silver in smelting dust are highly variable and inaccurate. Furthermore, the separate detection mode for gold and silver leads to a longer analysis cycle, significantly reducing detection efficiency and making it difficult to meet the needs of modern smelting production for rapid detection and feedback. Summary of the Invention

[0004] To overcome the above problems, the present invention provides a method for the joint determination of gold and silver in smelting flue dust.

[0005] The objective of this invention is achieved as follows:

[0006] A method for the joint determination of gold and silver in smelting flue dust includes the following steps:

[0007] Take a sample of smelting dust and transfer the sample to a crucible;

[0008] Take the following flux raw materials: sodium carbonate, lead oxide, glass powder, borax and flour; transfer the weighed flux raw materials into a crucible and cover the surface of the smelting fume sample with a covering agent;

[0009] Place the crucible in an electric furnace, heat it to melt, keep it at the temperature, and then remove it from the furnace. Pour the molten material into an iron mold, and after cooling, separate the lead buckle from the slag. Collect the initial slag and retain the initial melted lead buckle.

[0010] The initial molten lead buckle is blown with ash to obtain the initial granules, and the ash container is retained;

[0011] The initial slag and ash pan are crushed and then processed again according to the initial melting and ash blowing steps to obtain secondary granules.

[0012] The primary and secondary granules are added to an acid solution and heated to dissolve the silver in the granules. All the gold forms a precipitate in the acid solution.

[0013] Filter the acid solution after the reaction, retain the filtrate, washings and residue. Transfer the filtrate and washings to a volumetric flask and dilute to the mark to obtain solution I.

[0014] Add the filter residue to aqua regia, heat to dissolve the gold in the filter residue, and the silver that is not completely dissolved in the acid solution after the reaction forms silver chloride precipitate in the solution;

[0015] Filter the solution, retaining the filtrate, washings, filter paper, and residue; transfer the filtrate and washings to a volumetric flask and dilute to the mark to obtain solution II;

[0016] Transfer the filter paper and residue to a beaker, add hydrochloric acid and heat, then add nitric acid and perchloric acid, continue heating and cool; add hydrochloric acid and transfer the solution to a volumetric flask and dilute to the mark, this is solution III;

[0017] Dilute solutions I, II, and III;

[0018] The gold concentration in solution II was measured, and the gold concentration in the blank experiment was also measured. The gold content of the sample was then calculated.

[0019] The silver concentrations in solutions I, II, and III were measured, and the silver concentration in the blank experiment was also measured. The silver content in the sample was then calculated.

[0020] As a further preferred embodiment of the present invention, the method for joint determination of gold and silver in smelting flue dust as described above includes the following steps:

[0021] (1) Sample: Take 5g to 20g of smelting dust sample and transfer the sample to a fire test crucible;

[0022] (2) Blank experiment: A blank experiment was performed along with the smelting dust sample;

[0023] (3) Ingredients: Weigh each flux raw material according to the following mass: 40-50g sodium carbonate, 100-140g lead oxide, 10-25g glass powder, 10-15g borax and 4-5g flour, so that the flux can melt and smelt the dust sample.

[0024] The weighed fluxes are also transferred to the fire test crucible, stirred, and a 5-15 mm thick covering agent is applied to the surface of the smelting fume sample.

[0025] (4) Initial melting: Place the crucible in a fire test furnace at 850~950℃, close the furnace door, raise the temperature to 1050~1150℃ within 45 min~60 min, hold for 3~10 min and then take it out of the furnace. Rotate the crucible several times and tap it on the iron plate. Pour the molten material into the preheated iron mold. After cooling, separate the lead buckle from the slag, collect the initial slag and keep the initial molten lead buckle.

[0026] (5) Initial ash blowing: Place the initially molten lead buckle into the ash pan after preheating in the ash blowing electric furnace at 850~950℃ for 15~30 minutes. Close the furnace door for more than 1 minute. After the initially molten lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace at 860℃~880℃. Perform ash blowing in the airflow area until the ash blowing is completed to obtain the initial granules. Keep the ash pan.

[0027] (6) Secondary melting and ash blowing: After crushing the primary slag and the ash vessel after the first ash blowing, put them into the crucible used during the primary melting, and repeat the primary melting and ash blowing steps to obtain secondary aggregates.

[0028] (7) Processing of granules: Place the initial granulation in step (5) and the secondary granulation in step (6) into a beaker, add nitric acid aqueous solution, cover with a watch glass, heat to dissolve most of the silver in the granules, and a small amount of silver and all the gold form a precipitate in the solution.

[0029] (8) Filtration: Filter the solution in step (7) through slow filter paper, wash the cup wall and filter paper with nitric acid aqueous solution, retain the filtrate, washing liquid and filter residue, transfer the filtrate and washing liquid to the same volumetric flask and make up to the mark to obtain solution I;

[0030] (9) Treatment of filter residue: Transfer the filter residue to a beaker, add aqua regia, cover with a watch glass, heat to dissolve the gold in the filter residue, and after removing the acid, the small amount of silver that was not completely dissolved in step (7) forms silver chloride precipitate in the solution.

[0031] (10) Secondary filtration: Filter the solution in step (9) through slow filter paper, wash the cup wall and filter paper with hydrochloric acid aqueous solution, and retain the filtrate, washing liquid, filter paper and filter residue; transfer the filtrate and washing liquid to the same volumetric flask and make up to the mark to obtain solution II;

[0032] (11) Treatment of secondary filter residue: Transfer the filter paper and filter residue together to a beaker, add hydrochloric acid and heat for more than 3 minutes, remove and add nitric acid and perchloric acid, continue heating until the perchloric acid emits thick white fumes, continue heating to evaporate to dryness, remove and cool; add hydrochloric acid and heat to dissolve the salts, transfer the solution to a volumetric flask and dilute to the mark, which is solution III; dilute solutions I, II and III according to the gold and silver content in the sample;

[0033] (12) At a wavelength of 242.8 nm using an air-acetylene flame, the gold concentration in solution II was measured, and the gold concentration in the blank was also measured. The gold content in the sample was then calculated. At a wavelength of 328.1 nm using an air-acetylene flame, the silver concentration in solutions I, II and III was measured, and the silver concentration in the blank was also measured. The silver content in the sample was then calculated.

[0034] As a further preferred embodiment of the present invention, the gold content in the sample is calculated according to the following formula:

[0035] ;

[0036] in, This represents the mass fraction of gold in the sample, expressed in g / t. r 1 The mass concentration of gold in solution II is expressed in μg / mL. r 0 The mass concentration of gold in solution II, along with the blank experiment, is expressed in μg / mL. f 1 This is the dilution factor for solution II; V 1 This is the final volume of solution II, in mL; m 0 represents the mass of the sample, in grams;

[0037] Calculate the silver content in the sample using the following formula:

[0038] ;

[0039] in, This represents the mass fraction of silver in the sample, expressed in g / t. r 2 This represents the mass concentration of silver in solution II, in μg / mL. r 3 The mass concentration of silver in solution II, along with the blank experiment, is expressed in μg / mL. f 1 This is the dilution factor for solution II; V 1 This is the final volume of solution II, in mL; r 4 This represents the mass concentration of silver in solution I, in μg / mL. r 5 The mass concentration of silver in solution I, along with the blank experiment, is expressed in μg / mL. f 2 This represents the dilution factor of solution I; V 2 This is the final volume of solution I, in mL; r 6 This represents the mass concentration of silver in solution III, expressed in μg / mL. r 7 The mass concentration of silver in solution III, along with the blank experiment, is expressed in μg / mL. f 3 This is the dilution factor for solution III; V 3 This is the final volume of solution III, in mL; m 0 represents the mass of the sample, in grams.

[0040] As a further preferred embodiment of the present invention, the sample is weighed in step (1) to an accuracy of 0.1g, preferably 0.01g.

[0041] As a further preferred embodiment of the present invention, in step (1), 5g to 20g, and more preferably 5g to 15g of smelting dust sample, is weighed.

[0042] As a further preferred embodiment of the present invention, in step (3), the covering agent includes sodium carbonate and borax, with a mass ratio of (1~3):1, for example 3:1.

[0043] As a further preferred embodiment of the present invention, in step (3), the thickness of the covering agent is 5 to 15 mm, more preferably 5 to 10 mm, for example 10 mm.

[0044] As a further preferred embodiment of the present invention, in step (4), the crucible is placed in a fire assay furnace at 850~950°C, the furnace door is closed, and the temperature is raised to 1050~1150°C within 45 min~60 min, and held for 3~10 min. It is also preferred that the crucible is placed in a fire assay furnace at 900°C, the furnace door is closed, and the temperature is raised to 1100°C within 45 min~60 min, and held for 5 min before being removed from the furnace.

[0045] As a further preferred embodiment of the present invention, in step (5), the initially molten lead buckle is placed in an ash pan that has been preheated in an electric ash blowing furnace at 850~950℃ for 15~30 minutes. The furnace door is closed for more than 1 minute. After the initially molten lead buckle has completely melted, the furnace door is partially opened. The temperature of the electric ash blowing furnace is controlled at 860℃~880℃. Ash blowing is carried out in an airflow area. Alternatively, the initially molten lead buckle is placed in an ash pan that has been preheated in an electric ash blowing furnace at 950℃ for 20 minutes. The furnace door is closed for 1~2 minutes. After the initially molten lead buckle has completely melted, the furnace door is partially opened. The temperature of the electric ash blowing furnace is controlled at 860℃~880℃. Ash blowing is carried out in a stable airflow area until the ash blowing is completed, and the initial granulation is obtained. The ash pan is then retained.

[0046] As a further preferred embodiment of the present invention, in step (7), the nitric acid aqueous solution is an aqueous solution composed of nitric acid and water in a volume ratio of (0.5~1.5): (0.5~1.5), for example, an aqueous solution composed in a volume ratio of 1:1.

[0047] As a further preferred embodiment of the present invention, in step (7), the amount of the nitric acid aqueous solution is such that the amount of precipitate formed by the initial granulation in step (5) and the secondary granulation in step (6) no longer changes.

[0048] As a further preferred embodiment of the present invention, in steps (7) and (9), the heating temperatures are the same or different, and are independently 100~120°C, for example 110°C.

[0049] As a further preferred embodiment of the present invention, in step (8), the volume fraction of the nitric acid aqueous solution used for volume adjustment is 5-15%, for example 8-12%, such as 10%.

[0050] As a further preferred embodiment of the present invention, in step (9), the amount of aqua regia used is such that all the gold in the initial granulation in step (5) and the secondary granulation in step (6) is dissolved, or the amount of aqua regia is further increased by 1 to 5 mL, for example, by 1 to 2 mL.

[0051] As a further preferred embodiment of the present invention, in step (10), the volume fraction of the hydrochloric acid aqueous solution used for volume adjustment is 5-10%, for example 6-10%, such as 10%.

[0052] As a further preferred embodiment of the present invention, in step (11), the volume fraction of the hydrochloric acid aqueous solution used for volume adjustment is 10-20%, for example 15-18%, such as 15%.

[0053] As a further preferred embodiment of the present invention, in step (11), the hydrochloric acid used during heating after adding hydrochloric acid is concentrated hydrochloric acid, and the amount of hydrochloric acid used is enough to submerge the filter paper and filter residue.

[0054] As a further preferred embodiment of the present invention, in step (11), the nitric acid is concentrated nitric acid, and the amount of concentrated nitric acid used is (1 / 4 to 3 / 4) of the volume of hydrochloric acid added in this step.

[0055] As a further preferred embodiment of the present invention, in step (11), the perchloric acid is concentrated perchloric acid, and the amount of concentrated perchloric acid used is (1 / 10 to 2 / 5) of the volume of hydrochloric acid added in this step.

[0056] The beneficial effects of this invention are:

[0057] For the detection of gold and silver in smelting fumes, the presence of numerous impurities makes it difficult to obtain complete gold particles during the separation of the resulting gold-silver granules. This prevents the use of the classic fire assay gravimetric method for determining the gold and silver content. Furthermore, direct digestion of the gold-silver granules with aqua regia results in "passivation" due to silver oxidation, preventing complete dissolution of the gold within the granules. This invention employs a fire assay method with a larger sample size to enrich gold and silver. After obtaining the gold-silver granules, most of the silver is first dissolved using nitric acid solution. After filtration, the gold in the filter residue is dissolved using aqua regia. The residue is then filtered again to precipitate silver chloride, separating the gold and silver. The remaining small amount of silver in the filter residue is then dissolved. Finally, atomic absorption spectrometry is used to determine the gold content in the filtrate, as well as the silver content in the filtrate, filter residue, and gold-containing solution. The gold and silver content in the sample can then be calculated.

[0058] Smelting dust has a complex composition and relatively poor uniformity. This invention selects the fire assay method as the enrichment method, which allows for large sample sizes, more representative samples, and more stable test results. This invention uses the fire assay method to enrich gold and silver in the sample. The resulting gold-silver granules are first dissolved in nitric acid solution to remove most of the silver. After filtration, aqua regia is used to dissolve the gold in the filter residue. After filtering again to separate gold and silver by silver chloride precipitation, the remaining small amount of silver in the filter residue is dissolved. This segmented digestion method prevents "passivation" caused by direct dissolution of silver in the granules with aqua regia and ensures that both gold and silver in the granules are completely dissolved into the solution. Atomic absorption spectrometry is then used for the joint determination of gold and silver. Compared with the existing method of gold determination using the fire assay method and silver determination using atomic absorption spectrometry, this method shortens the detection process and improves detection efficiency, thus showing promising application prospects. Detailed Implementation

[0059] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0060] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0061] The operation method of the method for joint detection of gold and silver in smelting flue dust of the present invention is as follows.

[0062] Example 1

[0063] (1) Weigh 5.05g of smelting dust sample using a balance and transfer it to a fire test crucible.

[0064] (2) Perform blank experiments with the same sample throughout the entire process.

[0065] (3) Weigh out 40g of sodium carbonate, 100g of lead oxide, 10g of borax, 15g of glass powder and 4g of flour in sequence, stir evenly, transfer to a fire test crucible, and cover the surface of the smelting fume sample with a covering agent of about 10 mm thickness (the covering agent is composed of sodium carbonate and borax, with a mass ratio of sodium carbonate to borax of 3:1).

[0066] (4) Place the fire assay crucible in a fire assay furnace preheated to 900°C and close the furnace door. Increase the temperature to 1100°C within 45-60 minutes, hold for 5 minutes, and then remove from the furnace. Rotate the crucible smoothly several times and tap it gently two or three times on an iron plate. Carefully pour the molten material into a preheated iron mold. After cooling, separate the lead buckle from the slag, collect the slag (initial slag), and retain the lead buckle (initial molten lead buckle).

[0067] (5) Place the initially melted lead buckle into the ash pan after preheating in the ash blowing electric furnace at 950℃ for 20 minutes. Close the furnace door for 1 to 2 minutes. After the lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace to about 860℃ to 880℃. Perform ash blowing in a stable airflow area until the ash blowing is completed to obtain the initial granulation. Keep the ash pan.

[0068] (6) After crushing the initial slag and the ash vessel after the first ash blowing, put them into the crucible used during the initial melting, and repeat the initial melting and ash blowing steps to obtain secondary granules.

[0069] (7) Granulation treatment: Place the initial granulation in step (5) and the secondary granulation in step (6) into a 50 mL beaker, add 10 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water is 1:1), cover with a watch glass, and heat at 110℃ to dissolve most of the silver in the granulation. A small amount of silver and all of the gold form a precipitate in the solution.

[0070] (8) Filtration: Filter the solution from step (7) through slow filter paper. Wash the cup wall and filter paper multiple times with nitric acid aqueous solution, and retain the filtrate, washings and residue. Transfer the filtrate and washings to a 100 mL volumetric flask, dilute to the mark with 10% nitric acid aqueous solution, mix well and dilute 20 times to obtain solution I.

[0071] (9) Treatment of filter residue: Transfer the filter residue to a 25mL beaker, add 5mL of aqua regia, cover with a watch glass, and heat at 110℃ to dissolve all the gold in the filter residue. The small amount of silver that was not completely dissolved in step (7) forms silver chloride precipitate in the solution.

[0072] (10) Secondary filtration: Filter the solution from step (9) through slow filter paper, wash the cup wall and filter paper with aqua regia, and retain the filtrate, washings, filter paper and residue. Transfer the filtrate and washings to a 100mL volumetric flask and dilute to the mark with 10% hydrochloric acid aqueous solution to obtain solution II.

[0073] (11) Treatment of secondary filter residue: Transfer the filter paper and filter residue together to a 50mL beaker, add 15mL of concentrated hydrochloric acid and heat for 3-5 minutes. Remove the beaker and add 10mL of concentrated nitric acid and 3mL of concentrated perchloric acid. Continue heating until the perchloric acid emits concentrated white fumes, then continue heating to evaporate to dryness. Remove the beaker and cool. Add 5mL of concentrated hydrochloric acid and heat to dissolve the salts. Transfer the solution to a 100mL volumetric flask and dilute to the mark with 15% hydrochloric acid aqueous solution. This is Solution III.

[0074] (12) At a wavelength of 242.8 nm using an air-acetylene flame, the gold concentration in solution II was measured to be 1.503 μg / mL, and the gold concentration in the blank was measured to be 0.004 μg / mL. At a wavelength of 328.1 nm using an air-acetylene flame, the silver concentration in solution I was measured to be 1.478 μg / mL, and the silver concentration in the blank was 0.011 μg / mL; the silver concentration in solution II was 0.039 μg / mL, and the silver concentration in the blank was 0.007 μg / mL; the silver concentration in solution III was 0.104 μg / mL, and the silver concentration in the blank was 0.008 μg / mL.

[0075] (13) Calculation of results:

[0076] Calculate the gold content in the sample using the following formula:

[0077]

[0078] In the formula:

[0079] —Mass fraction of gold in the sample, g / t;

[0080] r 1 —The mass concentration of gold in solution II, in μg / mL;

[0081] r 0 —The mass concentration of gold in solution II, along with the blank, in μg / mL;

[0082] f 1 —Dilution factor of solution II;

[0083] V 1 —The final volume of solution II, in mL;

[0084] m 0 — Mass of the sample, in g.

[0085] Specifically:

[0086]

[0087] The calculated gold content is 29.68 g / t.

[0088] Calculate the silver content in the sample using the following formula:

[0089]

[0090] In the formula:

[0091] —Mass fraction of silver in the sample, g / t;

[0092] r 2 —The mass concentration of silver in solution II, in μg / mL;

[0093] r 3 —The mass concentration of silver in solution II, in μg / mL, is the same as that in the blank.

[0094] f 1 —Dilution factor of solution II;

[0095] V 1 —The final volume of solution II, in mL;

[0096] r 4 —The mass concentration of silver in solution I, in μg / mL;

[0097] r 5 —The mass concentration of silver in Solution I, along with the blank, in μg / mL;

[0098] f 2 —Dilution factor of solution I;

[0099] V 2—The final volume of solution I, in mL;

[0100] r 6 —The mass concentration of silver in solution III, in μg / mL;

[0101] r 7 —The mass concentration of silver in solution III, in the blank, in μg / mL;

[0102] f 3 —Dilution factor of solution III;

[0103] V 3 —The final volume of solution III, in mL;

[0104] m 0 — Mass of the sample, in g.

[0105] Specifically:

[0106]

[0107] The calculated silver content is 583.5 g / t.

[0108] Example 2

[0109] (1) Weigh 15.08g of smelting dust sample using a balance and transfer it to a fire test crucible.

[0110] (2) Perform blank experiments with the same sample throughout the entire process.

[0111] (3) Weigh out 40g of sodium carbonate, 140g of lead oxide, 10g of borax, 25g of glass powder and 4g of flour in sequence, stir evenly, transfer to a fire test crucible, and cover the surface of the smelting fume sample with a covering agent of about 10 mm thickness (the covering agent is composed of sodium carbonate and borax, with a mass ratio of sodium carbonate to borax of 3:1).

[0112] (4) Place the fire assay crucible in a fire assay furnace preheated to 900℃ and close the furnace door. Raise the temperature to 1100℃ within 45-60 minutes, hold for 5 minutes, and then remove from the furnace. Rotate the crucible smoothly several times and gently tap it two or three times on an iron plate. Carefully pour the molten material into a preheated iron mold. After cooling, separate the lead buckle from the slag, collect the slag (initial slag), and retain the lead buckle (initial molten lead buckle).

[0113] (5) Place the initially melted lead buckle into the ash pan after preheating in the ash blowing electric furnace at 950℃ for 20 minutes. Close the furnace door for 1 to 2 minutes. After the lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace to about 860℃ to 880℃. Perform ash blowing in a stable airflow area until the ash blowing is completed to obtain the initial granulation. Keep the ash pan.

[0114] (6) After crushing the initial slag and the ash vessel after the first ash blowing, put them into the crucible used during the initial melting, and repeat the initial melting and ash blowing steps to obtain secondary granules.

[0115] (7) Granulation treatment: Place the initial granulation in step (5) and the secondary granulation in step (6) into a 50 mL beaker, add 10 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water is 1:1), cover with a watch glass, and heat at 110℃ to dissolve most of the silver in the granulation. A small amount of silver and all of the gold form a precipitate in the solution.

[0116] (8) Filtration: Filter the solution from step (7) through slow filter paper. Wash the cup wall and filter paper multiple times with nitric acid aqueous solution, and retain the filtrate, washings and residue. Transfer the filtrate and washings to a 100 mL volumetric flask, dilute to the mark with 10% nitric acid aqueous solution, mix well and dilute 10 times to obtain solution I.

[0117] (9) Treatment of filter residue: Transfer the filter residue to a 25mL beaker, add 5mL of aqua regia, cover with a watch glass, and heat at 110℃ to dissolve all the gold in the filter residue. The small amount of silver that was not completely dissolved in step (7) forms silver chloride precipitate in the solution.

[0118] (10) Secondary filtration: Filter the solution from step (9) through slow filter paper, wash the cup wall and filter paper with aqua regia, and retain the filtrate, washings, filter paper and residue. Transfer the filtrate and washings to a 100mL volumetric flask, and dilute to the mark with a 10% hydrochloric acid aqueous solution to obtain solution II.

[0119] (11) Treatment of secondary filter residue: Transfer the filter paper and filter residue together to a 50mL beaker, add 15mL of concentrated hydrochloric acid and heat for 3-5 minutes. Remove the beaker and add 10mL of concentrated nitric acid and 3mL of concentrated perchloric acid. Continue heating until the perchloric acid emits concentrated white fumes, then continue heating to evaporate to dryness. Remove the beaker and cool. Add 5mL of concentrated hydrochloric acid and heat to dissolve the salts. Transfer the solution to a 100mL volumetric flask and dilute to the mark with a 15% (v / v) hydrochloric acid aqueous solution. This is Solution III.

[0120] (12) At a wavelength of 242.8 nm using an air-acetylene flame, the gold concentration in solution II was measured to be 3.264 μg / mL, and the gold concentration in the blank was measured to be 0.004 μg / mL. At a wavelength of 328.1 nm using an air-acetylene flame, the silver concentration in solution I was measured to be 1.484 μg / mL, and the silver concentration in the blank was 0.013 μg / mL; the silver concentration in solution II was 0.064 μg / mL, and the silver concentration in the blank was 0.009 μg / mL; the silver concentration in solution III was 0.121 μg / mL, and the silver concentration in the blank was 0.010 μg / mL.

[0121] (13) Calculation of results:

[0122] Calculate the gold content in the sample using the following formula:

[0123]

[0124] In the formula:

[0125] —Mass fraction of gold in the sample, g / t;

[0126] r 1 —The mass concentration of gold in solution II, in μg / mL;

[0127] r 0 —The mass concentration of gold in solution II, along with the blank, in μg / mL;

[0128] f 1 —Dilution factor of solution II;

[0129] V 1 —The final volume of solution II, in mL;

[0130] m 0 — Mass of the sample, in grams.

[0131] Specifically:

[0132]

[0133] The calculated gold content is 21.62 g / t.

[0134] Calculate the silver content in the sample using the following formula:

[0135]

[0136] In the formula:

[0137] —Mass fraction of silver in the sample, g / t;

[0138] r 2 —The mass concentration of silver in solution II, in μg / mL;

[0139] r 3 —The mass concentration of silver in solution II, in μg / mL, is the same as that in the blank.

[0140] f 1 —Dilution factor of solution II;

[0141] V 1 —The final volume of solution II, in mL;

[0142] r 4 —The mass concentration of silver in solution I, in μg / mL;

[0143] r 5 —The mass concentration of silver in solution I, along with the blank, in μg / mL;

[0144] f 2 —Dilution factor of solution I;

[0145] V 2 —The final volume of solution I, in mL;

[0146] r 6 —The mass concentration of silver in solution III, in μg / mL;

[0147] r 7 —The mass concentration of silver in Solution III, along with the blank, in μg / mL;

[0148] f 3 —Dilution factor of solution III;

[0149] V 3 —The final volume of solution III, in mL;

[0150] m 0 — Mass of the sample, in g.

[0151] Specifically:

[0152]

[0153] The calculated silver content is 98.65 g / t.

[0154] Experimental Example 3

[0155] Currently, there are no standard substances / standard samples for smelting flue dust. The accuracy of the joint detection method in this application is verified by using the spiked recovery rate method.

[0156] (1) Weigh 15.08g of the smelting dust sample from Example 2 using a balance and transfer it to a fire assay crucible. Weigh 0.163mg of pure gold and 1.486mg of pure silver and transfer them to the fire assay crucible as well.

[0157] (2) Perform blank experiments with the same sample throughout the entire process.

[0158] (3) Weigh out 40g of sodium carbonate, 140g of lead oxide, 10g of borax, 25g of glass powder and 4g of flour in sequence, stir evenly, transfer to a fire test crucible, stir evenly, and then cover the surface of the smelting fume sample with a covering agent of about 10 mm thickness (the covering agent is composed of sodium carbonate and borax, and the mass ratio of sodium carbonate to borax is 3:1).

[0159] (4) Place the fire assay crucible in a fire assay furnace preheated to 900℃ and close the furnace door. Raise the temperature to 1100℃ within 45-60 minutes, hold for 5 minutes, and then remove from the furnace. Rotate the crucible smoothly several times and gently tap it two or three times on an iron plate. Carefully pour the molten material into a preheated iron mold. After cooling, separate the lead buckle from the slag, collect the slag (initial slag), and retain the lead buckle (initial molten lead buckle).

[0160] (5) Place the initially melted lead buckle into the ash pan after preheating in the ash blowing electric furnace at 950℃ for 20 minutes. Close the furnace door for 1 to 2 minutes. After the lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace to about 860℃ to 880℃. Perform ash blowing in a stable airflow area until the ash blowing is completed to obtain the initial granulation. Keep the ash pan.

[0161] (6) After crushing the initial slag and the ash vessel after the first ash blowing, put them into the crucible used during the initial melting, and operate according to the initial melting and ash blowing steps to obtain secondary granules.

[0162] (7) Granulation treatment: Place the initial granulation in step (5) and the secondary granulation in step (6) into a 50 mL beaker, add 10 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water is 1:1), cover with a watch glass, and heat at 110℃ to dissolve most of the silver in the granulation. A small amount of silver and all of the gold form a precipitate in the solution.

[0163] (8) Filtration: Filter the solution from step (7) through slow filter paper. Wash the cup wall and filter paper multiple times with nitric acid aqueous solution, and retain the filtrate, washings and residue. Transfer the filtrate and washings to a 100 mL volumetric flask, dilute to the mark with 10% nitric acid aqueous solution, mix well and dilute 20 times to obtain solution I.

[0164] (9) Treatment of filter residue: Transfer the filter residue to a 25mL beaker, add 5mL of aqua regia, cover with a watch glass, and heat at 110℃ to dissolve all the gold in the filter residue. The small amount of silver that was not completely dissolved in step (7) forms silver chloride precipitate in the solution.

[0165] (10) Secondary filtration: Filter the solution in (9) through slow filter paper, wash the cup wall and filter paper with aqua regia, and retain the filtrate, washings, filter paper and residue. Transfer the filtrate and washings to a 100mL volumetric flask and dilute to the mark with 10% hydrochloric acid by volume to obtain solution II.

[0166] (11) Treatment of secondary filter residue: Transfer the filter paper and filter residue together to a 50mL beaker, add 15mL of concentrated hydrochloric acid and heat for 3-5 minutes. Remove the beaker and add 10mL of concentrated nitric acid and 3mL of concentrated perchloric acid. Continue heating until the perchloric acid emits concentrated white fumes, then continue heating to evaporate to dryness. Remove the beaker and cool. Add 5mL of concentrated hydrochloric acid and heat to dissolve the salts. Transfer the solution to a 100mL volumetric flask and dilute to the mark with 15% hydrochloric acid aqueous solution. This is Solution III.

[0167] (12) At a wavelength of 242.8 nm using an air-acetylene flame, the gold concentration in solution II was measured to be 4.894 μg / mL, and the gold concentration in the blank was measured to be 0.005 μg / mL. At a wavelength of 328.1 nm using an air-acetylene flame, the silver concentration in solution I was measured to be 1.486 μg / mL, and the silver concentration in the blank was 0.015 μg / mL; the silver concentration in solution II was 0.094 μg / mL, and the silver concentration in the blank was 0.008 μg / mL; the silver concentration in solution III was 0.213 μg / mL, and the silver concentration in the blank was 0.012 μg / mL.

[0168] (13) Calculation of results:

[0169] Calculate the gold content in the sample using the following formula:

[0170]

[0171] In the formula:

[0172] —Mass fraction of gold in the sample, g / t;

[0173] r 1 —The mass concentration of gold in solution II, in μg / mL;

[0174] r 0 —The mass concentration of gold in solution II, along with the blank, in μg / mL;

[0175] f 1 —Dilution factor of solution II;

[0176] V 1 —The final volume of solution II, in mL;

[0177] m 0 — Mass of the sample, in grams.

[0178] Specifically:

[0179]

[0180] The calculated gold content is 32.42 g / t, and the recovery rate is... .

[0181] Calculate the silver content in the sample using the following formula:

[0182]

[0183] In the formula:

[0184] —Mass fraction of silver in the sample, g / t;

[0185] r 2 —The mass concentration of silver in solution II, in μg / mL;

[0186] r 3 —The mass concentration of silver in solution II, in μg / mL, is the same as that in the blank.

[0187] f 1 —Dilution factor of solution II;

[0188] V 1 —The final volume of solution II, in mL;

[0189] r 4 —The mass concentration of silver in solution I, in μg / mL;

[0190] r 5—The mass concentration of silver in Solution I, along with the blank, in μg / mL;

[0191] f 2 —Dilution factor of solution I;

[0192] V 2 —The final volume of solution I, in mL;

[0193] r 6 —The mass concentration of silver in solution III, in μg / mL;

[0194] r 7 —The mass concentration of silver in solution III, in the blank, in μg / mL;

[0195] f 3 —Dilution factor of solution III;

[0196] V 3 —The final volume of solution III, in mL;

[0197] m 0 — Mass of the sample, in g.

[0198] Specifically:

[0199]

[0200] The calculated silver content is 197.00 g / t, and the recovery rate is... .

[0201] Comparative Example 1

[0202] (1) Weigh 5.05g of smelting dust sample using a balance and transfer it to a fire test crucible.

[0203] (2) Perform blank experiments with the same sample throughout the entire process.

[0204] (3) Weigh out 40g of sodium carbonate, 100g of lead oxide, 10g of borax, 15g of glass powder and 4g of flour in sequence, stir evenly, transfer to a fire test crucible, and cover the surface of the smelting fume sample with a covering agent of about 10 mm thickness (the covering agent is composed of sodium carbonate and borax, with a mass ratio of sodium carbonate to borax of 3:1).

[0205] (4) Place the fire assay crucible in a fire assay furnace preheated to 900°C and close the furnace door. Increase the temperature to 1100°C within 45-60 minutes, hold for 5 minutes, and then remove from the furnace. Rotate the crucible smoothly several times and tap it gently two or three times on an iron plate. Carefully pour the molten material into a preheated iron mold. After cooling, separate the lead buckle from the slag, collect the slag (initial slag), and retain the lead buckle (initial molten lead buckle).

[0206] (5) Place the initially melted lead buckle into the ash pan after preheating in the ash blowing electric furnace at 950℃ for 20 minutes. Close the furnace door for 1 to 2 minutes. After the lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace to about 860℃ to 880℃. Perform ash blowing in a stable airflow area until the ash blowing is completed to obtain the initial granulation. Keep the ash pan.

[0207] (6) After crushing the initial slag and the ash vessel after the first ash blowing, put them into the crucible used during the initial melting, and repeat the initial melting and ash blowing steps to obtain secondary granules.

[0208] (7) Granulation treatment: Place the initial granulation in step (5) and the secondary granulation in step (6) into a 50 mL beaker, add 10 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water is 1:1), cover with a watch glass, and heat at 110℃ to dissolve most of the silver in the granulation. A small amount of silver and all of the gold form a precipitate in the solution.

[0209] (8) Filtration: Filter the solution from step (7) through slow filter paper. Wash the cup wall and filter paper multiple times with nitric acid aqueous solution, and retain the filtrate, washings and residue. Transfer the filtrate and washings to a 100 mL volumetric flask, dilute to the mark with 10% nitric acid aqueous solution, mix well and dilute 20 times to obtain solution I.

[0210] (9) Treatment of filter residue: Transfer the filter residue to a 25mL beaker, add 5mL of aqua regia, cover with a watch glass, heat at 110℃ to dissolve all the gold in the filter residue, then transfer to a 100mL volumetric flask, and dilute to the mark with 10% hydrochloric acid aqueous solution to obtain solution II.

[0211] (10) At a wavelength of 242.8 nm using an air-acetylene flame, the gold concentration in solution II was measured to be 1.503 μg / mL, and the gold concentration in the blank was measured to be 0.004 μg / mL. At a wavelength of 328.1 nm using an air-acetylene flame, the silver concentration in solution I was measured to be 1.478 μg / mL, and the silver concentration in the blank was 0.011 μg / mL; the silver concentration in solution II was 0.039 μg / mL, and the silver concentration in the blank was 0.007 μg / mL.

[0212] (13) Calculation of results:

[0213] Calculate the gold content in the sample using the following formula:

[0214]

[0215] In the formula:

[0216] —Mass fraction of gold in the sample, g / t;

[0217] r 1 —The mass concentration of gold in solution II, in μg / mL;

[0218] r 0 —The mass concentration of gold in solution II, along with the blank, in μg / mL;

[0219] f 1 —Dilution factor of solution II;

[0220] V 1 —The final volume of solution II, in mL;

[0221] m 0 — Mass of the sample, in g.

[0222] Specifically:

[0223]

[0224] The calculated gold content is 29.68 g / t.

[0225] Calculate the silver content in the sample using the following formula:

[0226]

[0227] In the formula:

[0228] —Mass fraction of silver in the sample, g / t;

[0229] r 2 —The mass concentration of silver in solution II, in μg / mL;

[0230] r 3 —The mass concentration of silver in solution II, in μg / mL, is the same as that in the blank.

[0231] f 1 —Dilution factor of solution II;

[0232] V 1 —The final volume of solution II, in mL;

[0233] r 4 —The mass concentration of silver in solution I, in μg / mL;

[0234] r 5 —The mass concentration of silver in Solution I, along with the blank, in μg / mL;

[0235] f 2 —Dilution factor of solution I;

[0236] V 2 —The final volume of solution I, in mL;

[0237] m 0 — Mass of the sample, in g.

[0238] Specifically:

[0239]

[0240] The calculated silver content is 581.6 g / t.

[0241] The detection method in Comparative Example 1 failed to consider the residual silver in the secondary filter residue, resulting in a lower overall silver detection result.

[0242] Comparative Example 2

[0243] (1) Weigh 15.08g of smelting dust sample using a balance and transfer it to a fire test crucible.

[0244] (2) Perform blank experiments with the same sample throughout the entire process.

[0245] (3) Weigh out 40g of sodium carbonate, 140g of lead oxide, 10g of borax, 25g of glass powder and 4g of flour in sequence, stir evenly, transfer to a fire test crucible, and cover the surface of the smelting fume sample with a covering agent of about 10 mm thickness (the covering agent is composed of sodium carbonate and borax, with a mass ratio of sodium carbonate to borax of 3:1).

[0246] (4) Place the fire assay crucible in a fire assay furnace preheated to 900℃ and close the furnace door. Raise the temperature to 1100℃ within 45-60 minutes, hold for 5 minutes, and then remove from the furnace. Rotate the crucible smoothly several times and gently tap it two or three times on an iron plate. Carefully pour the molten material into a preheated iron mold. After cooling, separate the lead buckle from the slag, collect the slag (initial slag), and retain the lead buckle (initial molten lead buckle).

[0247] (5) Place the initially melted lead buckle into the ash pan after preheating in the ash blowing electric furnace at 950℃ for 20 minutes. Close the furnace door for 1 to 2 minutes. After the lead buckle has completely melted, half open the furnace door and control the temperature of the ash blowing electric furnace to about 860℃ to 880℃. Perform ash blowing in a stable airflow area until the ash blowing is completed to obtain the initial granulation. Keep the ash pan.

[0248] (6) After crushing the initial slag and the ash vessel after the first ash blowing, put them into the crucible used during the initial melting, and repeat the initial melting and ash blowing steps to obtain secondary granules.

[0249] (7) The mass of the gold and silver granules was measured by fire assay, and the total mass of the two granules was 1.816 mg.

[0250] (8) Granulation treatment: The first granulation in step (5) and the second granulation in step (6) are placed in colorimetric tubes, and 10 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water is 2:1) is added. After the reaction is complete, gold particles insoluble in nitric acid are obtained, dried and weighed to be 0.311 mg.

[0251] (9) Calculation of results:

[0252] Calculate the gold content in the sample using the following formula:

[0253]

[0254] In the formula:

[0255] —Mass fraction of gold in the sample, g / t;

[0256] m 1 —The mass of gold particles obtained after two rounds of granulation and separation, in mg;

[0257] m 2 —The mass of gold in the blank, mg;

[0258] m 0 — Mass of the sample, in g.

[0259] Specifically:

[0260]

[0261] The calculated gold content is 20.36 g / t.

[0262] Calculate the silver content in the sample using the following formula:

[0263]

[0264] In the formula:

[0265] —Mass fraction of silver in the sample, g / t;

[0266] m 3 —The combined mass of the two granules, in mg;

[0267] m 1 —The mass of gold particles obtained after two rounds of granulation and separation, in mg;

[0268] m 4 —The mass of silver in the blank, mg;

[0269] m 0 — Mass of the sample, in g.

[0270] Specifically:

[0271] The calculated silver content is 101.6 g / t.

[0272] The test results of Comparative Example 2 show that when using the conventional fire assay gravimetric method, due to the large number of impurity elements in the smelting fumes, it is impossible to remove all impurity elements during ash blowing. This easily causes gold particles to be crushed during gold separation, resulting in a systematic low detection result for gold and a systematic high detection result for silver. Therefore, it is necessary to use the fire assay enrichment-atomic absorption method to determine them separately, which lengthens the detection process and reduces the detection efficiency.

[0273] In summary, the combined detection method of the present invention has high accuracy and can accurately and quickly detect the content of gold and silver in smelting flue dust samples.

[0274] The exemplary embodiments of the present invention have been described above. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the joint determination of gold and silver in smelting flue dust, characterized in that, Includes the following steps: Take a sample of smelting dust and transfer the sample to a crucible; Take the following flux raw materials: sodium carbonate, lead oxide, glass powder, borax and flour; transfer the weighed flux raw materials into a crucible and cover the surface of the smelting fume sample with a covering agent; Place the crucible in an electric furnace, heat it to melt, keep it at the temperature, and then remove it from the furnace. Pour the molten material into an iron mold, and after cooling, separate the lead buckle from the slag. Collect the initial slag and retain the initial melted lead buckle. The initial molten lead buckles are blown with ash to obtain the initial granules, and the ash container is retained; The initial slag and ash pan are crushed and then the initial melting and ash blowing steps are repeated to obtain secondary granules. The primary and secondary granules are added to an acid solution and heated to dissolve the silver in the granules. All the gold forms a precipitate in the acid solution. After filtering the acid solution from the reaction, retain the filtrate, washings, and residue. Transfer the filtrate and washings to a volumetric flask and dilute to the mark to obtain solution I. Add the filter residue to aqua regia, heat to dissolve the gold in the filter residue, and the silver that is not completely dissolved in the acid solution after the reaction forms silver chloride precipitate in the solution; Filter the solution, retaining the filtrate, washings, filter paper, and residue; transfer the filtrate and washings to a volumetric flask and dilute to the mark to obtain solution II; Transfer the filter paper and filter residue to a beaker, add hydrochloric acid and heat, then add nitric acid and perchloric acid, continue heating and then cool; Add hydrochloric acid and transfer the solution to a volumetric flask, then dilute to the mark to obtain solution III; Dilute solutions I, II, and III; The gold concentration in solution II was measured, and the gold concentration in the blank experiment was also measured. The gold content of the sample was then calculated. The silver concentrations in solutions I, II, and III were measured, and the silver concentration in the blank experiment was also measured. The silver content in the sample was then calculated.

2. The joint testing method according to claim 1, characterized in that, Calculate the gold content in the sample using the following formula: ； in, This represents the mass fraction of gold in the sample, expressed in g / t. ρ 1 The mass concentration of gold in solution II is expressed in μg / mL. ρ 0 The mass concentration of gold in solution II, along with the blank experiment, is expressed in μg / mL. f 1 This is the dilution factor for solution II; V 1 This is the final volume of solution II, in mL; m 0 represents the mass of the sample, in grams; Calculate the silver content in the sample using the following formula: ； in, This represents the mass fraction of silver in the sample, expressed in g / t. ρ 2 This represents the mass concentration of silver in solution II, in μg / mL. ρ 3 The mass concentration of silver in solution II, along with the blank experiment, is expressed in μg / mL. f 1 This is the dilution factor for solution II; V 1 This is the final volume of solution II, in mL; ρ 4 This represents the mass concentration of silver in solution I, in μg / mL. ρ 5 The mass concentration of silver in solution I, along with the blank experiment, is expressed in μg / mL. f 2 This represents the dilution factor of solution I; V 2 This is the final volume of solution I, in mL; ρ 6 This represents the mass concentration of silver in solution III, expressed in μg / mL. ρ 7 The mass concentration of silver in solution III, along with the blank experiment, is expressed in μg / mL. f 3 This is the dilution factor for solution III; V 3 This is the final volume of solution III, in mL; m 0 represents the mass of the sample, in grams.

3. The joint testing method according to claim 1, characterized in that, Samples should be weighed to an accuracy of 0.1g; smelting dust samples should be weighed to a weight of 5g to 20g.

4. The joint testing method according to claim 1, characterized in that, The covering agent comprises sodium carbonate and borax in a mass ratio of (1~3):1; the thickness of the covering agent is 5mm~15mm.

5. The joint testing method according to claim 1, characterized in that, The specific steps for placing the crucible in the electric furnace are as follows: place the crucible in an electric furnace at 850℃~950℃, close the furnace door, raise the temperature to 1050℃~1150℃ within 45 min~60 min, hold the temperature for 3 min~10 min, and then remove it from the furnace.

6. The joint testing method according to claim 1, characterized in that, The specific steps for performing soot blowing on the initially melted lead buckles to obtain the initial granules and retaining the soot container are as follows: Place the initially melted lead buckles into the soot container after preheating in a soot blowing electric furnace at 850℃~950℃ for 15min~30min, close the furnace door for more than 1min, and after the initially melted lead buckles have completely melted, half open the furnace door, control the temperature of the soot blowing electric furnace at 860℃~880℃, and perform soot blowing in an airflow area until the soot blowing is completed to obtain the initial granules and retain the soot container.

7. The joint testing method according to claim 1, characterized in that, The acid solution added during the initial and secondary granulation processes consisted of nitric acid and water in a volume ratio of (0.5~1.5):(0.5~1.5).

8. The joint testing method according to claim 7, characterized in that, In the steps of heating and dissolving silver in the granules and heating and dissolving gold in the filter residue, the heating temperatures may be the same or different, and are independently 100℃~120℃.

9. The joint testing method according to claim 8, characterized in that, In the step of transferring the filtrate and washings to a volumetric flask and making up to the mark, the volume fraction of the nitric acid aqueous solution used for making up to the mark is 5% to 15%.

10. The joint testing method according to claim 9, characterized in that, In the step of transferring the filtrate and washings to a volumetric flask and making up to the mark, the volume fraction of the hydrochloric acid aqueous solution used for making up to the mark is 5% to 10%. In the step of adding hydrochloric acid and transferring the solution to a volumetric flask and making up to the mark, the volume fraction of the hydrochloric acid aqueous solution used for making up to the mark is 10% to 20%.

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