Method for high-pressure airtight determination of silver in copper ore

Abstract

The invention discloses a method for high-pressure airtight determination of silver in copper ore, which adopts high-pressure airtight digestion-inductively coupled plasma emission spectrometry to determine the silver element in the copper ore, and comprises the following steps: accurately weighing 0.1000 g of copper ore sample into a polytetrafluoroethylene inner tank of a high-pressure airtight digestion tank, adding 3mL of hydrofluoric acid and 7mL of nitric acid to soak the sample for 12 hours, stirring for 20-30 minutes, and then taking out the sample; 0.1 mL of hydrogen peroxide is added before the polytetrafluoroethylene inner tank is sealed, after the inner tank is screwed, the metal outer tank is screwed, the polytetrafluoroethylene inner tank is put into an anti-corrosion constant-temperature drying oven, the temperature is increased to 160 DEG C from the low temperature, the temperature is kept for 6 hours, the polytetrafluoroethylene inner tank is taken out after being cooled to the room temperature, the volume is fixed to 10 mL, and a nitric acid solution with the volume fraction being 20% serves as a medium. And determining the content of the silver element in the copper ore under the optimal working condition of the inductively coupled plasma emission spectrometer. The method has the advantages of simple and convenient detection process, low economic cost of equipment, high sensitivity, low detection limit, accurate determination result, wide determination content range, less interference, environmental friendliness and the like, and also meets the detection requirements of simultaneously treating a large batch of geological ore samples.

Description

Technical Field

[0001] The invention belongs to the technical field of copper ore detection, and in particular relates to a method for high-pressure closed determination of silver in copper ore. Background Art

[0002] Silver, as an important precious metal element, exists mainly in the form of silver-containing compound ores in nature. Silver has stable chemical properties, low activity, and good thermal and electrical conductivity. China is a country with medium-abundance silver resources. Understanding the content of silver in ores has important guiding significance for mineral processing research and improving comprehensive utilization rates.

[0003] There are many methods for detecting silver in ores, but there are few standard methods for detecting silver in copper ores. At present, the methods for determining silver in geological samples include AC arc-emission spectrometry, atomic absorption spectrophotometry, X-ray fluorescence spectrometry, inductively coupled plasma emission spectrometry, and inductively coupled plasma emission mass spectrometry. Among them, the silver content of soil, water sediments, and rocks is generally between 1 μg·g -1 Below, the AC arc-emission spectrometry direct reading method can be used; Liu Tao et al. reported the use of emission spectrometry to determine copper, lead, zinc, and molybdenum in water sediments, but for samples with high silicate content, the measured values ​​will be low; Yuan Hui established a hot plate digestion-dynamic discrimination mode-inductively coupled plasma emission mass spectrometry method to determine the amount of silver in geochemical exploration samples. The instrument kinetic energy discrimination mode was used, and helium was used as the collision gas to analyze silver, which reduced the interference of polyatomic ions on silver, and is suitable for the determination of silver in large-scale exploration samples.

[0004] When the silver content is determined by AC arc-emission spectroscopy direct reading method, it is greater than 10 μg g -1It cannot be accurately determined and cannot be applied to the determination of high-content silver in ores; when inductively coupled plasma emission mass spectrometry is used to determine silver in ores, the contents of various associated metal elements are also high, such as lead, zinc, tungsten, molybdenum, tin, etc., which will interfere with the determination results of inductively coupled plasma mass spectrometry, and the injection pipeline is easily contaminated, resulting in a memory effect that is not easy to eliminate, and the determination solution is diluted at a large multiple, which affects the accuracy of the determination results; atomic absorption spectrophotometry is also a common method for determining silver in ores, but the instrument has low determination sensitivity and the sample pretreatment process is complicated and cumbersome, so atomic absorption spectrophotometry also has its limitations; occasionally, literature reports say that X-ray fluorescence spectrometers are used to determine silver in ores. Although the determination method is simple and can melt complex ore samples, the method is immature and the equipment is expensive. In addition, there are few relevant domestic and international standards for the detection of silver in copper ores. The Japanese standard method is the determination of gold and silver content in ores (JIS M8111-1998); the current domestic standard methods include Chemical analysis methods for copper ores, lead ores and zinc ores Part 11: Determination of silver content by flame atomic absorption spectrophotometry (GB / T 14353.11-2010), and Chemical analysis methods for black copper Part 2: Determination of gold and silver content by fire assay (YS / T 716.2-2009).

[0005] There are few relevant standards for the detection of silver in copper ore at home and abroad. The Japanese standard method for the determination of gold and silver content in ore (JIS M8111-1998) has a silver determination range of 1g / t-1500g / t. The ore sample is mixed with ingredients, melted at high temperature, and the lead collector is used to capture gold and silver. After ash blowing, sulfuric acid separation or nitric acid separation, gold is analyzed by weight method or atomic absorption method and inductively coupled plasma emission spectrometry can also be used to determine gold and silver. The pre-treatment process of this standard method is relatively long, and the loss of the element to be measured during the treatment process is relatively large.

[0006] At present, the current standard methods in China include Chemical Analysis Methods for Copper Ore, Lead Ore and Zinc Ore Part 11: Determination of Silver Content by Flame Atomic Absorption Spectrophotometry (GB / T 14353.11-2010). This standard specifies the method for determining the amount of silver in copper ore, lead ore and zinc ore, with a determination range of 10μg·g -1 -500μg·g -1, after the ore sample is burned at 600℃, it is first decomposed with hydrofluoric acid and perchloric acid and evaporated. Then it is dissolved in aqua regia to a paste and leached with ammonia water. In a 20% ammonia water medium, an air-acetylene flame is used to measure the absorbance at a wavelength of 324.7nm with an atomic absorption spectrophotometer to calculate the amount of silver. The atomic absorption spectrophotometry used in this standard is an element analysis method established by utilizing the phenomenon that the middle and outer electrons of atoms are unstable and can absorb light radiation of a certain wavelength, causing the electrons to transition from the ground state to the excited state. Although atomic absorption spectrophotometry has the advantages of low detection limit, high sensitivity, and fast analysis speed, there is interference between different elements, and it is impossible to analyze multiple elements simultaneously. The power lamp needs to be frequently replaced when measuring different elements. Therefore, the application of atomic absorption spectrophotometry also has its limitations.

[0007] Chemical analysis method for black copper Part 2: Determination of gold and silver content by fire assay (YS / T 716.2-2009). This standard specifies the determination method for gold and silver content in black copper. The determination range is silver greater than or equal to 20 μg·g -1 The ore is mixed and melted at high temperature. The molten lead captures the precious metals in the sample to form lead buckles. Other substances in the sample and the flux form fusible slag. The lead buckle ash is blown to obtain gold and silver particles. The impurities adhering to the surface of the particles are removed, and the gold is separated by nitric acid, and the silver content is determined by titration. This standard uses the pre-treatment method of lead gold assay to capture gold and silver in black copper. After separating gold and silver, the silver solution is titrated with potassium thiocyanate standard solution to determine the silver content. The previous processing process was relatively long, and the titration method had the disadvantages of low sensitivity and large interference, which easily caused large errors in the final measurement results.

[0008] Therefore, it is necessary to find a standard detection method that is simple, feasible, accurate, reliable, has a wide measurement range, is reasonably priced, and is suitable for large quantities of ore samples. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a method for determining silver in copper ore. The method adopts a combination of high-pressure closed digestion and inductively coupled plasma emission spectroscopy to determine the silver in the copper ore, and utilizes a combination of a high-pressure closed corrosion-resistant digestion tank and a common anti-corrosion constant temperature oven to treat the copper ore sample, which not only reduces the detection limit of the method, but also reduces the reagent usage and instrument procurement cost, improves the detection efficiency, and increases the determination range of silver in copper ore, thereby meeting the determination requirements of large batches of geological copper ore samples.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] The invention discloses a method for determining silver in copper ore. The method adopts high-pressure sealed digestion-inductively coupled plasma emission spectrometry to determine the silver element in the copper ore. The method comprises the following steps: weighing 0.1000g of copper ore sample into a polytetrafluoroethylene inner tank of a high-pressure sealed anti-corrosion digestion tank, adding 3mL of hydrofluoric acid and 7mL of nitric acid to soak the sample for 12 hours, adding 0.1mL of hydrogen peroxide before sealing the polytetrafluoroethylene inner tank, screwing the inner tank tightly, and then screwing the metal outer tank tightly, putting the sample into an anti-corrosion constant temperature oven, heating the sample from low temperature to 160°C for 6 hours, cooling the sample to room temperature, taking the sample out, placing the sample on a constant temperature electric heating plate for 20 minutes and keeping the sample at 80°C, and then making the yellow nitrogen dioxide gas evaporate completely, and then fixing the sample to a 10mL colorimetric tube. The medium is a nitric acid solution with a volume fraction of 20%. Under the optimal working conditions of an inductively coupled plasma emission spectrometer, the content of the silver element in the copper ore is determined. The method can process about 200 ore samples at one time, and fully meets the processing requirements of large quantities of geological copper ore samples.

[0012] Furthermore, under the optimal working conditions of the instrument, samples with a content of 3 to 5 times the estimated detection limit of the method were selected according to the test steps, and 21 full-process blank tests were performed. The t-fold standard deviation of the 21 measured values ​​was calculated and the detection limit of the method was calculated by considering the sample weight and dilution multiple. The detection limit of the method was 0.021 μg·g -1 The lower limit of determination is 0.085 μg·g -1 .

[0013] Furthermore, the national primary standard material GBW07233 (Ag content 3.9 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07169(Ag content 154μg·g -1 ) The decomposition ability of different combinations of hydrofluoric acid, nitric acid and hydrogen peroxide was investigated, and the optimal combination ratio of reagents used to decompose copper ore was determined to be 3mL hydrofluoric acid + 7mL nitric acid + 0.1mL hydrogen peroxide.

[0014] Furthermore, the national primary standard material GBW07368 (Ag content 8.77 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 ) was used to investigate the digestion effect of copper ore at different closed digestion temperatures, and the optimal digestion temperature was determined to be 160℃.

[0015] Furthermore, the national primary standard material GBW07233 (Ag content 3.9 μg g -1 )、GBW07370(Ag content 43.2μg·g -1)、GBW07367(Ag content 103μg·g -1 ) The digestion efficiency of copper ore was investigated under different digestion time conditions, and the optimal digestion time was determined to be 6h.

[0016] Furthermore, Ag328.068nm was selected as the characteristic spectral line for measuring silver.

[0017] Furthermore, the optimal working conditions of the inductively coupled plasma emission spectrometer are: RF transmission power 1150W; cooling gas (Ar) flow rate 12L / min; auxiliary gas (Ar) flow rate 0.5L / min; nebulizer pressure 0.2MPa; observation mode vertical; observation height 12mm; flushing pump speed 50r / min; analysis pump speed 50r / min; solution lifting volume 1.5mL / min; sample flushing time 5s; measurement mode peak area; integration time short wave 9s; integration time long wave 6s.

[0018] Furthermore, the national primary standard material GBW07233 (Ag content 3.9 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07169(Ag content 154μg·g -1 ) 12 test solutions were prepared in parallel and determined by inductively coupled plasma emission spectrometry. The precision (RSD) of the calculation method was between 0.59 and 1.21%, and the correctness (RD) was between -0.62 and 0.19%.

[0019] Furthermore, the national primary standard material GBW07368 (Ag content 8.77 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 ), added different amounts of Ag standard solution, carried out spike recovery experiment according to the test steps, and determined by inductively coupled plasma emission spectrometry. The recovery rates of silver element were between 95% and 105%, which met the requirements of quality management specifications.

[0020] Beneficial effects of the invention: The method of the invention adopts a combination of high-pressure closed digestion and inductively coupled plasma emission spectrometry to analyze the silver element in copper ore, and has the advantages of simple detection process, low equipment economic cost, high sensitivity, low detection limit, accurate measurement results, wide measurement content range, less interference, and environmental friendliness. It also meets the detection needs of simultaneously processing large batches of geological ore samples.

[0021] The present invention adopts high pressure closed digestion of copper ore, which not only improves the dissolution efficiency, but also greatly reduces the amount of reagents used, reducing the harm to the environment and analysts. At the same time, combined with ICP-AES, it not only improves the detection efficiency and the accuracy of the method, but also broadens the determination range of the method. The detection limit, precision, correctness and spike recovery of the method meet the requirements of the geological and mineral laboratory test quality management specification (DZ / T 0130-2006), providing an inspection and detection basis for the determination of silver in copper ore.

[0022] The present invention determines the best spectral line and working conditions for determining silver element by inductively coupled plasma spectrometry through spectral line selection, interference factor condition experiments and optimization and adjustment of instrument related parameters; taking advantage of the high-pressure closed tank, selecting a suitable solvent not only accelerates the digestion of copper ore, but also eliminates S 2 O 3 - , CN - , Cl - Br - , S - and organic suspended matter on Ag + Adsorption and precipitation can improve the accuracy of determination;

[0023] This method is applicable to copper ores with different silver contents. The use process is easy to promote and is applicable to the pretreatment of large batches of geological samples. It has strong market competitiveness and will surely produce good economic and social benefits. Compared with the current national standard method, this method has a simpler process, a wide measurement range, and high sensitivity. It is applicable to copper ore samples with different silver contents, has strong market competitiveness, and will surely produce good economic and social benefits. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention.

[0025] Hydrofluoric acid (superior grade), nitric acid (superior grade), hydrogen peroxide (superior grade), deionized water for laboratory use;

[0026] Silver element standard stock solution (1000 mg / L): A high-purity metal (purity greater than 99.99%) or metal salt (reference or high-purity reagent) can be used to prepare a 1000 mg / L standard stock solution containing 10% nitric acid (V / V); or a certified standard solution can be used.

[0027] Example 1

[0028] The method for determining silver in copper ore by high pressure closed digestion-inductively coupled plasma emission spectrometry of this embodiment comprises the following steps:

[0029] ① Accurately weigh 0.1000g of copper ore sample and put it into a high-pressure closed digestion tank. Add 3mL of hydrofluoric acid and 7mL of nitric acid respectively. After a few minutes when the bubbles disappear, gently close the lid of the digestion tank to prevent foreign matter from falling into the tank and contaminating it. Place it at room temperature for 12 hours.

[0030] ② Add 0.1mL of hydrogen peroxide solution to the sample that has been soaked for 12 hours, wait for a while, tighten the high-pressure sealed digestion inner tank, and then tighten the metal outer tank. Place it in a constant temperature anti-corrosion oven, raise it from room temperature to 160℃ and keep it for 6 hours, then put it back to room temperature, take it out, open the lid of the digestion inner tank, and place it on a constant temperature electric heating plate for 20 minutes to maintain 80℃, so that the yellow nitrogen dioxide gas will be exhausted.

[0031] ③ Before adjusting the volume, add 2 mL of concentrated nitric acid solution to each 10 mL colorimetric tube, then completely transfer the digestion solution in the digestion tank to the colorimetric tube, and adjust the volume to 10 mL with laboratory deionized water, keeping the medium as 20% nitric acid solution by volume for testing.

[0032] ④ According to the instrument working conditions: RF transmission power 1150W; cooling gas (Ar) flow rate 12L / min; auxiliary gas (Ar) flow rate 0.5L / min; nebulizer pressure 0.2MPa; observation mode vertical; observation height 12mm; flushing pump speed 50r / min; analysis pump speed 50r / min; solution lifting volume 1.5mL / min; sample flushing time 5s; measurement method peak area; integration time short wave 9s; integration time long wave 6s. Select Ag328.068nm as the measurement wavelength, establish the analysis method, and determine the mass concentration of silver in the blank test solution, standard substance solution and sample solution according to the measurement conditions. If the sample concentration exceeds the highest point of the calibration curve, it can be diluted for measurement.

[0033] ⑤ Drawing of calibration curve: Add 0mL, 0.50mL, 1.00mL, 2.50mL, 5.00mL, 10.00mL of silver standard solution (1000mg / L) to a set of 100mL volumetric flasks, dilute to scale with 10% (V / V) nitric acid, shake well, the concentration of silver is: 0μg / mL, 5μg / mL, 10μg / mL, 25μg / mL, 50μg / mL, 100μg / mL, and measure the emission intensity in order from low to high concentration. The mass concentration of silver in the calibration solution series is the horizontal axis, and the emission intensity value measured by the calibration solution series is the vertical axis. The calibration curve is automatically drawn by the computer and stored. The concentration value of silver in the sample extract is obtained from the calibration curve.

[0034] 1. Selection of the best spectral line and working conditions for silver element inductively coupled plasma spectrometry

[0035] In the spectral library of the inductively coupled plasma emission spectrometer, the four characteristic spectral lines of silver are Ag328.068, Ag338.289, Ag243.779, and Ag224.641. For qualitative analysis, as long as the characteristic wavelength is determined, the requirements can be met; but for quantitative analysis, it is necessary to select more appropriate characteristic spectral lines for analysis based on the matrix characteristics of the instrument and the sample. Since the analysis wavelengths of some elements are similar, there may be interference or overlap between the spectral lines of different elements. The selection of the analysis spectral line directly determines the accuracy of the test results. In addition, it is also necessary to take into account factors such as sample composition, background interference, relative sensitivity, and signal-to-noise ratio. Since copper ore is a polymetallic ore, its rock-forming elements and some metal elements are high in content. Combined with the spectral library information, Ti338.376, Mn243.737, and Cu224.700 were determined as interfering elements. High concentrations of Ti, Mn, and Cu element standard solutions were added to the high concentration Ag standard solution to make the Ag concentration at 50 mg / mL, the Ti concentration at 20 mg / mL, the Mn concentration at 50 mg / mL, and the Cu concentration at 50 mg / mL. The solution to be tested after copper ore digestion was simulated and an interfering element experiment was performed. See Table 1 for details.

[0036] Table 1 Interference element experiment

[0037]

[0038] As can be seen from Table 1, the interference element experiment was carried out on the four characteristic spectral lines. High concentrations of Ti, Mn and Cu elements all interfered with the three characteristic spectral lines of Ag338.289, Ag243.779 and Ag224.641. Although the measurement results were close to the standard solution concentration value after deducting the interference, considering that the contents of Ti, Mn and Cu elements in copper ore are relatively high, Ag328.068, which is not interfered by the three elements of Ti, Mn and Cu, was selected as the characteristic spectral line for the determination of silver.

[0039] In addition, the suitability of the instrument working conditions also directly affects the accuracy and reproducibility of the analysis results. Therefore, it is necessary to optimize and adjust the relevant parameters of the instrument. By changing the single factor conditions, the influence on the analysis results was studied. A 1% concentration of Cu standard solution was used to change the carrier gas flow rate, auxiliary gas flow rate, cooling gas flow rate, carrier gas pressure, etc. in turn to observe the change trend of the analysis intensity caused by the change of the single factor conditions. Finally, the optimal instrument analysis conditions were determined: RF transmission power 1150W; cooling gas (Ar) flow rate 12L / min; auxiliary gas (Ar) flow rate 0.5L / min; nebulizer pressure 0.2MPa; observation mode vertical; observation height 12mm; flushing pump speed 50r / min; analysis pump speed 50r / min; solution lifting volume 1.5mL / min; sample flushing time 5s; determination method peak area; integration time short wave 9s; integration time long wave 6s.

[0040] 2. Choice of digestion acid

[0041] Silver in copper ore usually exists in the form of sulfide, which is an easily atomized element with almost no interference from coexisting ions. However, if S 2 O 3 - , CN - , Cl - Br - , S - and organic suspended matter, will make Ag + Being adsorbed and precipitated, it is particularly important to choose the right acid to digest the copper ore. This method uses hydrofluoric acid to dissolve the silicates in the copper ore, so that the silver element in the silicate structure can be released, and the strong oxidizing property of nitric acid is used to dissolve the silver in most sulfides in the ore. Combined with the strong oxidizing property of a small amount of hydrogen peroxide, the complete digestion process of the copper ore is enhanced. In a corrosion-resistant closed digestion tank, a high-pressure environment is used to accelerate the complete digestion of the copper ore by the acid. Compared with ordinary open mixed acid digestion systems, it can greatly decompose the sample completely; and compared with microwave acid digestion systems, the economic cost of the equipment has also been reduced to a certain extent. Therefore, this method has great advantages in pre-treatment capabilities and is easier to promote.

[0042] 3. Digestion acid ratio experiment

[0043] In order to determine the optimal combination ratio of acid reagents used to decompose copper ore, the national primary standard material GBW07233 (Ag content 3.9 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07169(Ag content 154μg·g -1) weighed 0.1000g, and 6 portions of each standard sample were made. The constant temperature oven was maintained at 150℃ and the time was set for 10h. The results were averaged to investigate the digestion ability of different combinations of hydrofluoric acid + nitric acid (1mL+3mL, 2mL+5mL, 3mL+7mL, 5mL+10mL). Finally, 0.1mL of hydrogen peroxide was added before sealing the tank, and a closed digestion acid ratio experiment was carried out on the copper ore. The detailed data are shown in Table 2.

[0044] Table 2 Digestion acid ratio experiment

[0045]

[0046] It can be seen from the data in Table 2 that when the amount of hydrofluoric acid + nitric acid is too small, it is not enough to completely dissolve the ore, resulting in a low silver result; when the digestion acid ratio is 3mL + 7mL + 0.1mL hydrogen peroxide and 5mL + 10mL + 0.1mL hydrogen peroxide, the silver results are close to the certified values ​​of the standard substance, indicating that the digestion acid ratio of 3mL + 7mL + 0.1mL hydrogen peroxide can completely digest the ore. Taking environmental factors into consideration, this digestion acid ratio is the most appropriate.

[0047] 4. Digestion temperature experiment

[0048] Digestion temperature is an important factor affecting sample pretreatment. If the temperature is too low, the sample will not be completely decomposed, resulting in a low measurement result. If the temperature is too high, not only will the energy consumption increase, but also the risk of explosion due to excessive pressure. This method selects the national first-level standard material GBW07368 (Ag content 8.77μg·g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 ) Weigh 0.1000g, make 6 portions of each standard sample, set the temperature of the constant temperature oven to 130℃, 140℃, 150℃, 160℃, 170℃, and 180℃ respectively, and take the average value of the results after setting the time to 10h to examine the digestion effect of copper ore at different dissolution temperatures. Detailed data are shown in Table 3.

[0049] Table 3 Digestion temperature experiment

[0050]

[0051]

[0052] It can be seen from the data in Table 3 that when the temperature is 130℃, 140℃, and 150℃, it is not enough to completely open the internal structure of the copper ore, and the digestion is incomplete, resulting in low measurement results; when the temperature is 160℃, 170℃, and 180℃, the measurement results are consistent with the certified values ​​of the standard substances. Considering the energy consumption and safety issues of daily work, 160℃ is selected as the optimal digestion temperature.

[0053] 5. Digestion time experiment

[0054] In order to improve the digestion efficiency and determine the optimal digestion time, the national first-level standard material GBW07233 (Ag content 3.9 μg g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 ) Weigh 0.1000g, make 6 copies of each standard sample, set the temperature of the constant temperature oven to 160℃, and set the time to 3h, 4h, 5h, 6h, 7h, 8h respectively. Take the average value of the results to investigate the digestion efficiency of copper ore under different digestion time conditions. Detailed data are shown in Table 4.

[0055] Table 4. Digestion time experiment

[0056]

[0057] It can be seen from the data in Table 4 that when the digestion time was 3h and 4h, the internal structure of the ore sample was not completely opened, and the measurement results were generally low; when the digestion time was selected at 5h, the analysis results were significantly improved, but there was still a certain error with the certified value of the standard substance; when the digestion temperature was 6h, 7h, and 8h, the measurement results were consistent with the certified value of the standard material. Taking into account the factors of analysis cost and work efficiency, 6h was determined as the optimal digestion time.

[0058] 6. Method detection limit and determination limit

[0059] In accordance with the relevant provisions of the Technical Guidelines for the Formulation and Revision of Environmental Monitoring Analytical Methods (HJ 168-2010), samples with a concentration of 3 to 5 times the expected method detection limit were used to perform 21 full-process treatments and measurements according to the given analytical method, and the method detection limit and determination lower limit were calculated. The results are shown in Table 5.

[0060] Table 5 Detection limit and determination limit of silver element by inductively coupled plasma emission spectrometry

[0061]

[0062] 7. Precision and accuracy of the method

[0063] According to the experimental steps, the national first-level standard material GBW07233 (Ag content 3.9 μg·g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07169(Ag content 154μg·g -1 ) 12 solutions to be tested were prepared in parallel, and the results were determined by inductively coupled plasma emission spectrometry, and the precision and accuracy of the method were calculated. The results are shown in Table 6.

[0064] Table 6 Accuracy and precision of Ag element determined by high pressure closed digestion-ICP-AES

[0065]

[0066] 8. Recovery rate of the method

[0067] The national primary standard material GBW07368 (Ag content 8.77 μg·g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 ), add different amounts of Ag standard solution, perform spike recovery experiment according to the experimental steps, and measure by inductively coupled plasma emission spectrometry to verify the accuracy of the method. The results are shown in Table 7. The recovery rate of silver element is between 95% and 105%, which meets the requirements of relevant quality management specifications.

[0068] Table 7 Recovery of Ag element determined by high pressure closed digestion-ICP-AES

[0069]

[0070] 9. Analysis and summary report of main tests (or verification tests) and technical and economic demonstration

[0071] Comparison of different methods

[0072] The national standard method GB / T 14353.11-2010 "Methods for chemical analysis of copper, lead and zinc ores Part 11: Determination of silver content by flame atomic absorption spectrophotometry" uses flame atomic absorption spectrophotometry to determine the silver element. Currently, most testing laboratories use this method, but this standard method needs to be carried out in an ammonia medium. When the silver content is high, the analysis results of the ammonia medium are often low. The reason is that the hydroxide precipitation in the ammonia solution has an adsorption effect on silver ions, and ammonium salts are easy to clog the burner, especially when using a water-cooled burner. The impact is more serious, and sometimes even leads to an inability to read; although the atomic absorption spectrophotometry has the advantages of low detection limit, high sensitivity, and fast analysis speed, there is interference between different elements, and it is not possible to analyze multiple elements simultaneously. The power lamp needs to be frequently replaced when determining different elements. Therefore, the application of atomic absorption spectrophotometry also has its limitations.

[0073] The representative national primary standard material GBW07233 (Ag content 3.9 μg·g -1 )、GBW07368(Ag content 8.77μg·g -1 )、GBW07370(Ag content 43.2μg·g -1 )、GBW07367(Ag content 103μg·g -1 )、GBW07169(Ag content 154μg·g -1 ), and compared them by high pressure sealed-inductively coupled plasma emission spectrometry and national standard method GB / T 14353.11-2010 flame atomic absorption spectrophotometry, respectively. The results are shown in Table 8.

[0074] Table 8 Comparison of silver element analysis methods

[0075]

[0076] From the above results, it can be seen that the results of the established high-pressure closed-inductively coupled plasma emission spectrometry method, RE%, meet the quality requirements for silver elements in the geological and mineral industry standard DZ / T0130-2006 of the People's Republic of China. For copper ore samples, there is no significant difference in the determination results with the current national standard method GB / T 14353.11-2010.

[0077] 10. The degree of adoption of international and foreign standards and their comparison with national and similar domestic standards

[0078] At present, there are few relevant standards for the detection of silver in copper ores at home and abroad, including the Japanese standard method for the determination of gold and silver content in ores (JIS M 8111-1998), the chemical analysis method of copper ore, lead ore and zinc ore Part 11: Determination of silver content by flame atomic absorption spectrophotometry (GB / T 14353.11-2010), and the chemical analysis method of black copper Part 2: Determination of gold and silver content by fire assay (YS / T 716.2-2009). However, the fire assay method for the determination of silver in ore has strict operating conditions, high cost, and slow speed, and cannot quickly guide production. The current standard method in the testing laboratory is GB / T 14353.11-2010. The representative national primary standard material GBW07233 (Ag content 3.9μg·g -1 )、GBW07367(Ag content 103μg·g -1 ), the present method was compared with the national standard method (GB / T 14353.11-2010), JIS M8111-1998, and YS / T716.2-2009 for Ag determination, see Table 9 for details.

[0079] Table 9 Comparison of Ag determination between this method and foreign and domestic standard methods

[0080]

[0081] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for determining silver in copper ore under high pressure and in a closed environment. It is characterized in that The silver element in copper ore was determined by high-pressure closed digestion-inductively coupled plasma emission spectrometry, comprising the following steps: accurately weighing 0.1000g of copper ore sample into the polytetrafluoroethylene inner tank of the high-pressure closed digestion tank, adding 3mL of hydrofluoric acid and 7mL of nitric acid to soak the sample for 12h, adding 0.1mL of hydrogen peroxide before sealing the polytetrafluoroethylene inner tank, tightening the inner tank, and then tightening the metal outer tank, placing it in an anti-corrosion constant temperature oven, raising the temperature from low temperature to 160℃ and maintaining it for 6 hours, cooling it to room temperature and then taking it out, fixing the volume to a 10mL colorimetric tube, and determining the content of silver element in the copper ore under the optimal working conditions of the inductively coupled plasma emission spectrometer.

2. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The detection limit of the method was 0.021µg•g -1 The lower limit of determination is 0.085µg•g -1 .

3. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The national first-class standard material GBW07233 (Ag content 3.9µg·g -1 )、GBW07370(Ag content 43.2µg·g -1 )、GBW07169(Ag content 154µg·g -1 ) The decomposition capabilities of different combinations of hydrofluoric acid, nitric acid, and hydrogen peroxide were investigated, and the optimal combination ratio of reagents used to decompose copper ore was determined to be 3mL hydrofluoric acid + 7mL nitric acid + 0.1mL hydrogen peroxide.

4. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The national first-class standard material GBW07368 (Ag content 8.77µg·g -1 )、GBW07370(Ag content 43.2µg·g -1 )、GBW07367(Ag content 103µg·g -1 ) was used to investigate the digestion effect of copper ore at different closed digestion temperatures, and the optimal digestion temperature was determined to be 160℃.

5. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The national first-class standard material GBW07233 (Ag content 3.9µg·g -1 )、GBW07370(Ag content 43.2µg·g -1 )、GBW07367(Ag content 103µg·g -1 ) The digestion efficiency of copper ore was investigated under different digestion time conditions, and the optimal digestion time was determined to be 6h.

6. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: Ag328.068nm was selected as the characteristic spectral line for the determination of silver.

7. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The medium used to make up the volume in the colorimetric tube is a nitric acid solution with a volume fraction of 20%.

8. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The optimal working conditions of the inductively coupled plasma emission spectrometer are as follows: RF transmission power 1150 W; cooling gas (Ar) flow rate 12 L / min; auxiliary gas (Ar) flow rate 0.5 L / min; nebulizer pressure 0.2 MPa; observation mode vertical; observation height 12 mm; flushing pump speed 50 r / min; analysis pump speed 50 r / min; solution lifting volume 1.5 mL / min; sample flushing time 5 s; determination mode peak area; integration time short wave 9 s; integration time long wave 6 s.

9. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The national first-class standard material GBW07233 (Ag content 3.9µg·g -1 )、GBW07370(Ag content 43.2µg·g -1 )、GBW07169(Ag content 154µg·g -1 ) 12 test solutions were prepared in parallel and determined by inductively coupled plasma emission spectrometry. The precision (RSD) of the calculation method was between 0.59 and 1.21%, and the correctness (RD) was between -0.62 and 0.19%.

10. The method for determining silver in copper ore in a high pressure and closed manner according to claim 1, Features: The national first-class standard material GBW07368 (Ag content 8.77µg·g -1 )、GBW07370(Ag content 43.2µg·g -1 )、GBW07367(Ag content 103µg·g -1 ), different amounts of Ag standard solution were added respectively, and the spike recovery experiment was carried out according to the test steps. The recovery rates of silver element were determined by inductively coupled plasma emission spectrometry and were between 95% and 105%, which met the requirements of quality management specifications.

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