A method for determining silver in gold ore

Abstract

The present invention belongs to the field of metal analysis and determination, and specifically relates to a method for determining silver in gold ore. A method for decomposing and determining silver in gold ore of the present invention comprises the steps of: wetting the gold ore sample with pure water, adding Br2-H2O and NaCl, heating to a slightly boiling state, maintaining for a period of time, and then cooling to room temperature. The method adopts a bromine water-sodium chloride digestion system to analyze and determine the silver in the gold ore, establishes a field non-acid rapid, green, and efficient method for analyzing Ag, and solves the technical problems of reagent pollution and transportation and use risks brought about by the traditional acid method for measuring silver.

Description

Technical Field

[0001] The invention belongs to the field of metal analysis and determination, and particularly relates to a method for determining silver in gold ore. Background Art

[0002] Due to its unique rarity, the application scope of gold ore is expanding day by day, and its economic value and research significance are becoming more and more important. As an important copper-loving element and medium-volatile element, silver (Ag) has important tracer value in high-temperature geological processes (such as core-mantle differentiation, crust-mantle material exchange, key metal mineralization, etc.).

[0003] In remote exploration areas such as the west, due to inconvenient transportation, the process from sample collection and transportation to laboratory analysis and testing requires a lot of manpower, material resources and time costs. At the same time, the transportation and inherent testing cycle make it impossible for the timeliness of obtaining test results to meet the requirements of gold resource exploration and drilling construction progress, thus delaying important decision-making opportunities in the field investigation and drilling construction process, making it difficult to achieve the goal of quickly finding gold mines.

[0004] The rapid field analysis of silver has always been an important topic in the current analytical field, and it is of great significance to improve the exploration and development of gold mines. As early as the 1980s and 1990s, many analysts have conducted rapid field analysis of silver. At present, there are many methods for analyzing silver, such as fire assay weight method, manual titration method, colorimetry, chemiluminescence method, etc.; there are also improved potentiometric titration method, catalytic photometry, polarography, dry-wet combination, etc. on this basis; there are also acid digestion-fluorescence photometry, atomic absorption spectrophotometry, etc., which are commonly used in recent years. These methods usually require extraction, enrichment and other pretreatments of adding organic reagents during sample preparation, which have problems such as long sample processing time, cumbersome process, introduction of complex matrix, and harm to the human body caused by the required organic reagents. The dry decomposition method of gold mine samples is suitable for fire assay, which requires the use of high-power equipment and has potential environmental pollution problems, and is not suitable for use under field conditions. The wet method mainly includes hydrochloric acid method, nitric acid method, aqua regia method, nitric acid-hydrochloric acid-perchloric acid method, chlorine water method, etc., due to the different dissolving reagents. The acid dissolution method is easy to operate, the blank is easy to control, and it is suitable for mass production, so it is most suitable for geological experimental testing. However, these dissolution methods use a large amount of dangerous chemicals such as hydrochloric acid, nitric acid, and perchloric acid, which leads to many difficulties in the procurement, transportation, use, and management of reagents, and are easy to pollute the environment, making them unsuitable for field analysis. Limited by field environmental conditions and analytical testing equipment, the existing field rapid methods are inefficient, have poor results, and are not environmentally friendly.

[0005] As reagent control becomes increasingly stringent, it is urgent to develop accurate, efficient and green methods for rapid field analysis of silver in gold ore. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for determining silver in gold ore, which solves the technical problems of low efficiency, poor results, and environmental protection of the field determination method of silver in the prior art.

[0008] (II) Technical solution

[0009] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, an embodiment of the present invention provides a method for determining silver in gold ore, comprising the steps of:

[0011] Digestion steps: Wet the gold ore with pure water, add Br 2 -H 2 O and NaCl, heated to a slightly boiling state, maintained for a period of time, and then cooled to room temperature, so that the silver in the gold ore sample to be tested is digested and released into the solution.

[0012] Bromine water-sodium chloride mixture is used as the digestion system for sample decomposition. The strong oxidizing property of bromine water is used to oxidize the chlorine provided by sodium chloride in the solution into new ecological chlorine, and then oxidize the Ag in the gold ore sample into high-valent, forming chloride complex anions that enter the solution to achieve the purpose of decomposition. This method replaces various acidic hazardous chemical reagents commonly used in the original method. It is green and environmentally friendly, and is more suitable for large-scale sample analysis in the field. The reaction equation is as follows:

[0013] Br 2 +2e=2Br -

[0014] Ag+2Cl - =AgCl 2 +2e

[0015] Ag+Br 2 +2Cl - =AgCl 2 +2Br -

[0016] As can be seen from the reaction formula, the decomposition process of Ag is a process in which redox reaction and complex reaction are carried out simultaneously, which has nothing to do with acidity. The entire reaction process does not use acid and does not produce acid, so it meets the requirements of today's green environmental protection and has great application prospects in field rapid analysis methods.

[0017] When the silver content in the gold ore sample is different, the gold ore is 0.2-1g, and 5mL-10mL of 50% nitric acid is added for redissolution, so that a more accurate result can be obtained.

[0018] Optionally, the Br 2 -H 2 The molar ratio of O to NaCl is 1:1-2. Preferably, the Br 2 -H 2 The molar ratio of O to NaCl is 1:1.3.

[0019] Weigh 1.0000 g of standard materials for gold and silver component analysis GBW07203-GBW07209 and gold ore component standard materials GBW(E)070236-GBW(E)070238, respectively, and add 0.5% Br 2 -H 2 O + 0.5% NaCl, 1.0% Br 2 -H 2 O + 1.5% NaCl, 1.0% Br 2 -H 2 O + 2.0% NaCl, 1.5% Br 2 -H2O+2% bromine water-sodium chloride with different concentrations were used in the experiment to study the digestion effect of different proportions of digestion reagents on silver in the ore. From the results, it can be seen that in the digestion process, if the proportion of the selected digestion reagent is too large or too small, the relative error (RE / %) of the test result is large, and when the proportion of the digestion reagent is 1.5%Br 2 -H 2 O + 2% NaCl, that is, 1% Br 2 -H 2 When O+1.3%NaCl, the RE / % of the measured result is smaller. This is because Br 2 The reaction equivalent with NaCl is 1:1. In order to ensure sufficient complexation effect, the proportion of NaCl is appropriately increased. After comprehensive consideration, the reagent ratio of 1.5% Br is selected. 2 -H 2 O + 2% NaCl was used as the digestion reagent.

[0020] Optionally, the gold ore is 0.2-1g, the Br 2 -H 2 The volume of the mixture of O and NaCl is 10-30 mL. Preferably, the Br 2 -H 2 The volume of the mixture of O and NaCl was 20 mL.

[0021] Weigh 1.0000 g of standard materials for gold and silver component analysis GBW07203-GBW07209 and gold ore component standard materials GBW(E)070236-GBW(E)070238 in the ore, select 1.5% Br 2 -H 2 A mixed solvent of 0.04% NaCl was used as a digestion reagent, and the optimal amount of the digestion reagent was studied by changing the amount of the mixed solvent added. 10mL, 15mL, 20mL, 25mL, and 30mL of the reagent were added respectively, and the experiment was carried out according to the experimental method. From the results, it can be seen that when the amount of solvent added is greater than 15mL, the relative error (RE / %) of the test result tends to be stable, indicating that the test result has met the actual requirements. After comprehensive consideration, the amount of digestion reagent added is selected as 20mL.

[0022] Optionally, the duration of the slight boiling state is 10-50 minutes, preferably, the duration of the slight boiling state is 30 minutes.

[0023] Weigh 1.0000 g of standard materials for gold and silver component analysis GBW07203-GBW07209 and gold ore component standard materials GBW(E)070236-GBW(E)070238 in the ore, select 1.5% Br 2 -H 2 20mL of mixed solvent of O+2%NaCl ratio was used as digestion reagent, and the digestion time was 10, 20, 30, 40, 50min as variables, and the experiment was carried out according to the experimental method. From the results, it can be seen that with the extension of time, the results of Ag test show an increasing trend. When the time exceeds 30min, the time has little effect on the digestion effect, indicating that this method has a higher dissolution rate for Ag in the ore. Therefore, 30min is selected as the best digestion time.

[0024] Optionally, the heating temperature is 60-220°C, preferably, the heating temperature is 220°C.

[0025] Weigh 1.0000 g of standard materials for gold and silver component analysis GBW07203-GBW07209 and gold ore component standard materials GBW(E)070236-GBW(E)070238 in the ore, select 1.5% Br 2 -H 220mL of mixed solvent with a ratio of O+2% NaCl was used as the digestion reagent, and the digestion was carried out for 30 minutes at 60±5℃, 100±5℃, 140±5℃, 180±5℃, and 220±5℃ respectively as the temperature variables, and the experiment was carried out according to the experimental method. From the results, it can be seen that with the increase of temperature, the Ag test results show an increasing trend. When the temperature is 220±5℃, the slightly boiling state of the sample digestion can be well guaranteed, and the dissolution is more complete. Therefore, 220±5℃ is selected as the optimal digestion temperature.

[0026] Optionally, the method for determining silver in gold ore further comprises a determination step, and the determination step comprises:

[0027] A series of gold ore standard substances with known silver content were digested according to the same digestion treatment, the digested solutions were diluted, the absorbance was measured and a standard curve was prepared;

[0028] The digestion solution of the gold ore sample to be tested is transferred to a container, diluted to a fixed volume with water, the absorbance is measured, and the mass concentration of silver is obtained by comparing with the standard curve and the mass fraction of silver in the sample to be tested is calculated.

[0029] Optionally, the mass fraction of silver in the gold ore standard substance is determined by flame atomic absorption spectrometry.

[0030] (III) Beneficial effects

[0031] This method adopts a bromine water-sodium chloride digestion system to analyze and determine the silver in gold ore, establishes a field non-acid rapid, green and efficient method for analyzing Ag, and solves the technical problems of reagent contamination and transportation and use risks brought about by the traditional acid method for silver determination.

[0032] The method has the advantages of high sensitivity, precise accuracy, lower detection limit, strong anti-interference ability, etc., and does not require pretreatment processes such as extraction and enrichment to add organic reagents, which simplifies the operation and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a standard working curve diagram of silver in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0035] Br in the present invention 2 -H 2 O is saturated bromine water.

[0036] Example 1

[0037] A method for decomposing and determining silver in gold ore of the present invention comprises the steps of:

[0038] Drawing of standard curve: Pipette 0, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mL of 50 mg / L silver standard solution into several 100 mL volumetric flasks, dilute to the scale with (3+17) hydrochloric acid, and mix well. Adjust to zero with the reagent blank and measure the absorbance. Draw the standard curve with the silver concentration as the horizontal axis and the absorbance as the vertical axis. The mass concentrations of silver in this standard curve are 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5 mg / L, respectively. The standard curve is Abs=0.0002046075+0.02238294ρ (ρ is the concentration of the solution to be tested, μg / mL)

[0039] Sample digestion: Weigh 0.2000g of gold ore sample into a 50mL glass beaker, moisten with a small amount of water, add 20mL of 1.5% Br2-H2O + 2% NaCl mixed solvent, place on a hot plate and heat to 220℃ slightly boiling state, keep for more than 30min, when the test solution volume is about 5mL, remove and cool to room temperature. Transfer the test solution to a 100mL volumetric flask, dilute with water to the scale, mix well, and let stand to clarify. Use the absorbance of the sample solution to check the mass concentration ρ of silver from the standard curve and calculate the mass fraction of silver in the sample to be tested.

[0040] Calculate the mass fraction of silver according to the following formula:

[0041] ω Ag =ρ×V / m

[0042] ω Ag —mass fraction of silver, in grams per ton (g / t);

[0043] ρ—The mass concentration of silver is obtained from the standard curve by the absorbance of the sample solution, in micrograms per milliliter (μg / mL);

[0044] V—volume of the sample solution, in milliliters (mL);

[0045] m—mass of the sample, in grams (g).

[0046] Example 2

[0047] Sample digestion: weigh 0.5000g of gold ore sample into a 50mL glass beaker, moisten with a small amount of water, add 1.5% Br 2 -H 2Place 30 mL of O+1.5% NaCl mixed solvent on a hot plate and heat to a slightly boiling state of 220°C, maintain for more than 30 minutes, and when the test solution volume is about 5 mL, remove and cool to room temperature. Transfer the test solution to a 100 mL volumetric flask, dilute to the mark with water, mix well, and let stand to clarify.

[0048] Example 3

[0049] Sample digestion: weigh 1.000g of gold ore sample into a 50mL glass beaker, moisten with a small amount of water, add 1.5% Br 2 -H 2 Place 20 mL of O+1.5% NaCl mixed solvent on a hot plate and heat to a slightly boiling state of 100°C, maintain for more than 20 minutes, and when the test solution volume is about 5 mL, remove and cool to room temperature. Transfer the test solution to a 50 mL volumetric flask, dilute to the mark with water, mix well, and let stand to clarify.

[0050] Example 4

[0051] Sample digestion: weigh 1.000g of gold ore sample into a 50mL glass beaker, moisten with a small amount of water, add 1.5% Br 2 -H 2 Place 10 mL of O+2% NaCl mixed solvent on a hot plate and heat to a slightly boiling state of 150°C, maintain for more than 40 minutes, and when the test solution volume is about 5 mL, remove and cool to room temperature. Transfer the test solution to a 25 mL volumetric flask, dilute to the mark with water, mix well, and let stand to clarify.

[0052] Test example

[0053] 1. Method detection limit and quantification limit

[0054] According to the evaluation method for method detection limit (MDL) and quantification limit (MDQ) in GB / T 27417-2017 "Guidelines for Conformity Assessment of Chemical Analysis Methods for Confirmation and Validation", 11 sample flow blank solutions were prepared and measured using the digestion method of Example 1, and the standard deviation (s) was calculated. MDL was calculated as t(n-1,0.99)×s=2.764×s, and MDQ was calculated as 4 times the detection limit. The results were 0.083g / t and 0.332g / t, respectively. The specific test results are shown in Table 1.

[0055] Table 1 Detection limit and quantification limit of Ag element

[0056]

[0057] 2 Method precision and accuracy

[0058] According to the method of Example 1, three gold ore component analysis standard materials GBW07207, GBW07209, and GBW(E)070236 with different contents were measured in parallel 6 times, and the relative standard deviation (RSD / %) and relative error (RE / %) of the measured values ​​were calculated. The results are shown in Table 2.

[0059] Table 2 Method precision and accuracy results

[0060]

[0061]

[0062] (1) Determination of Ag content in gold ore standard material

[0063] According to the method of Example 1, 10 gold ore component analysis standard substances with different Ag contents were measured, and the relative errors (RE / %) between the measured values ​​and the certified values ​​of the standard substances were calculated. The results are shown in Table 3.

[0064] Table 3 Gold ore composition analysis standard substance Ag test results

[0065]

[0066] (2) Determination of Ag content in actual gold ore samples

[0067] Taking 6 actual samples of gold ore as an example, the actual samples are numbered Sample 1-Sample 6. According to the determination method of the present invention, the gold content in the 6 actual samples of gold ore is determined respectively according to the method of Example 1 by comparing with the standard working curve, and the method control experiment is carried out using the "Chemical Analysis Method of Gold Ore Part 2 Determination of Silver Content Flame Atomic Absorption Spectrometry" (GB / T 20899.2-2019), and the relative error (RD / %) of the measured value is calculated. The results are shown in Table 4.

[0068] Table 4 Gold ore actual sample Ag test results

[0069]

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining silver in gold ore, characterized in that: Includes steps: Digestion steps: Wet the gold ore with pure water, add Br2-H2O and NaCl, heat to a slightly boiling state, keep for a period of time, and then cool to room temperature to allow the silver in the gold ore sample to be digested and released into the solution.

2. The measuring method according to claim 1, characterized in that When the gold ore weighs 0.2-1 g and the silver content in the gold ore is 1 g / t to 1000 g / t, 5 mL to 10 mL of nitric acid with a volume fraction of 50% is added.

3. The measuring method according to claim 1, characterized in that The molar ratio of Br2-H2O to NaCl is 1:1-2, preferably, the molar ratio of Br2-H2O to NaCl is 1:1.

3.

4. The measuring method according to claim 1, characterized in that The gold ore is 0.5-1.5 g, and the volume of the Br2-H2O and NaCl mixture is 10-30 mL. Preferably, the volume of the Br2-H2O and NaCl mixture is 20 mL.

5. The measuring method according to claim 1, characterized in that The duration of the slight boiling state is 10-50 minutes, preferably, the duration of the slight boiling state is 30 minutes.

6. The measuring method according to claim 1, characterized in that The heating temperature is 60-220°C, preferably, the heating temperature is 220°C.

7. The measuring method according to claim 1, characterized in that The method further comprises a determination step, wherein the determination step comprises: A series of gold ore standard substances with known silver content were digested according to the same digestion treatment, the digested solutions were diluted, the absorbance was measured and a standard curve was prepared; The digestion solution of the gold ore sample to be tested is transferred to a container, diluted to a fixed volume with water, the absorbance is measured, and the mass concentration of silver is obtained by comparing with the standard curve and the mass fraction of silver in the sample to be tested is calculated.

8. The measuring method according to claim 7, characterized in that The mass fraction of silver in gold ore standard material was determined by flame atomic absorption spectrometry.

Images