Quantitative determination method of trace harmful elements in flotation products of rare polymetallic ores

Abstract

The present invention discloses a method for quantitative determination of trace harmful elements in various flotation products of rare polymetallic ores, which includes three parts: sample processing, preparation of complex matrix standard solution and sample testing. Each flotation product is digested with analytically pure concentrated nitric acid; the main mineral species of each product are determined by XRD, and the high-purity standard substances of each main associated mineral are digested with analytically pure concentrated nitric acid, and the content of harmful elements to be monitored is determined by ICP-MS after appropriate dilution; each standard substance digestion solution is diluted to a major element concentration of 1000μg / mL, and used to dilute the harmful element standard stock solution to obtain standard solutions with different concentration gradients; then the process blank and digestion sample are tested using an inductively coupled plasma mass spectrometer using a combination of internal standard method and matrix matching to obtain the content of trace harmful elements to be measured. It effectively overcomes the mass spectrometry and non-mass spectrometry interference problems faced by complex matrix sample testing, is suitable for the analysis and testing of trace element content in complex samples, and has a simple method and is easy to operate.

Description

Technical Field

[0001] The present invention relates to an ICP-MS determination method for trace elements in complex minerals, in particular to a quantitative determination method for trace harmful elements in various flotation products of rare polymetallic ores. Background Art

[0002] Multi-stage flotation of complex rare metals such as tungsten, molybdenum, tin, and bismuth yields qualified products including molybdenum concentrate, bismuth concentrate, sulfur concentrate, and mixed black and white tungsten concentrate, as well as intermediate and tailings products such as full flotation concentrate / tailings and black and white tungsten tailings. Routine testing at concentrators primarily focuses on rare metals such as tungsten, molybdenum, tin, and bismuth, but testing for trace levels of harmful elements has yet to be conducted. With rising product quality requirements and increasing environmental protection pressures, improving quantitative analysis methods for trace harmful elements in various flotation products is imperative.

[0003] Currently, the main methods for accurately quantifying trace elements include ICP-MS, ICP-OES, and atomic absorption spectrometry. However, the standard curves underlying these quantitative methods are often established based on conventional simple matrix standard solutions. These methods primarily utilize simple matrix standard solutions for testing. After digestion, mineral samples must be diluted significantly to approximate the matrix of the standard solution. During this dilution process, the content of harmful elements in the mineral digestate decreases, and may even become undetectable. Lowering the dilution factor results in low internal standard recovery, impacting the accuracy of the results. There is a significant concentration difference between the standard solution and the flotation product digestate. While diluting the digestate can reduce the concentration gradient to some extent, the content of the element being measured will also decrease, approaching or even falling below the detection limit of the test method. Therefore, optimization of test methods for quantifying trace harmful elements in flotation products of rare metals with complex matrices is urgently needed. Summary of the Invention

[0004] Technical Problem: The purpose of the present invention is to overcome the shortcomings of the existing ICP-MS technology in accurately quantifying the content of trace harmful elements in complex matrices, and to provide a method for quantitatively determining trace harmful elements in various flotation products of rare polymetallic ores that combines a matrix matching method and an internal standard method. By increasing the number of elements in the complex matrix, further reducing the concentration difference between the complex matrix standard solution and the matrix of the sample to be measured, and optimizing the ICP-MS test parameters, the mass spectrometry and non-mass spectrometry interferences generated by the complex matrix are effectively overcome, thereby achieving accurate quantification of trace elements in complex matrix samples.

[0005] Technical Solution: To achieve the above-mentioned purpose, the present invention provides a method for quantitatively determining trace harmful elements in various flotation products of rare and polymetallic ores. The method comprises three parts: sample processing, preparation of a complex matrix standard solution, and sample testing. The specific process includes:

[0006] Step 1: Filter, dry and grind the flotation product of the rare metal ore to obtain a powder sample;

[0007] Step 2: Weigh 0.1 g of powder sample into a polytetrafluoroethylene digestion tank, add 4 mL of aqua regia, and gently shake to mix the powder sample and aqua regia to obtain a sample to be digested. Simultaneously, prepare another blank sample 1 containing only 4 mL of aqua regia without the powder sample;

[0008] Step 3: Cover the polytetrafluoroethylene digestion tanks containing the sample to be digested and the blank sample 1 and place them in the digestion instrument. Heat them to 200 degrees and maintain for 3 hours. After heating is completed and naturally cooled, take out the digestion tank, open the lid and release the gas to obtain the sample digestion solution 1 and the blank sample 2.

[0009] Step 4: Transfer the sample digestion solution 1 and blank sample 2 to a 200 mL volumetric flask, and dilute to volume with 2% ultrapure dilute nitric acid to obtain sample digestion solution 2 and blank sample 3;

[0010] Step 5: Perform XRD phase analysis on the powder sample obtained in step 1 to obtain the main mineral components in the powder sample;

[0011] Step 6: Based on the main minerals contained in the powder sample, purchase the corresponding high-purity standard material, crush and grind it to obtain -74μm fine-grained standard material;

[0012] Step 7: Based on the chemical composition of the -74μm fine-grained standard material, calculate the mass of the fine-grained standard material required to obtain the cations in the main associated minerals of 0.1g powder sample;

[0013] Step 8: Digest the -74 μm fine particle standard material according to the method of steps 2-4, and dilute the volume to 100 mL with 2% ultrapure dilute nitric acid to obtain -74 μm standard material digestion solution 1 and blank sample 5;

[0014] Step 9: Use 2% ultrapure dilute nitric acid to dilute the harmful element stock solution in the pure matrix to prepare standard solutions 1 containing a concentration gradient of 10, 20, 50, 100, 200 and 500 μg / L of the harmful element;

[0015] Step 10: Use ICP-MS to test the standard solution 1, the standard substance digestion solution 1 and the blank solution 5 in sequence using the internal standard method to obtain a standard curve of harmful elements in a simple matrix. The content C of harmful elements in the standard substance digestion solution 1 is obtained based on the standard curve of harmful elements in a simple matrix background. i , and then according to the harmful element content C i Calculate the harmful element content C of the solid sample in the standard substance ig ;

[0016] Step 11: Calculate the volume required to prepare the standard solution 2 with a concentration gradient based on the concentration of the harmful elements in the harmful element stock solution and the standard substance digestion solution 1;

[0017] Step 12: dilute the harmful element stock solution of the pure matrix with the standard substance digestion solution 1 prepared in step 8, and prepare a standard solution 2 containing the harmful element with a concentration gradient of 10, 20, 50, 100, 200 and 500 μ;

[0018] Step 13: Use ICP-MS to test the standard solution 2, sample digestion solution 2 and blank sample 3 using the internal standard method to obtain a standard curve of harmful elements in a complex matrix background, and calculate the trace element content in each flotation product of the rare polymetallic ore based on the standard curve.

[0019] The 2% ultrapure dilute nitric acid is prepared by diluting ultrapure concentrated nitric acid with ultrapure water having a resistivity of ≥18MΩ·cm.

[0020] The trace harmful elements in the powder sample are Cu, Zn, As, Cd and Pb.

[0021] The elements selected for the internal standard method are 72 Ge, 115 In and 209 Bi.

[0022] After the standard substance is digested and diluted to a fixed volume, the element concentration in the standard substance digestion solution 1 is 1000 μg / mL.

[0023] In step nine, the volume of 2% dilute nitric acid required for preparing the standard solution 1 containing the concentration gradient of harmful elements is calculated according to the following formula:

[0024] (50-V k )*C b =50*C1

[0025] Where: V k is the volume of 2% dilute nitric acid required, C b is the concentration of harmful elements in the harmful element stock solution, here it is 10mg.L -1 ; C1 is the concentration of harmful elements in the prepared standard solution 1, 10, 20, 50, 100, 200 and 500 μg / L.

[0026] In step 10, the content of harmful elements in the standard substance C is calculated based on the standard curve of harmful elements in the simple matrix background. ig , the specific calculation formula is as follows:

[0027] Y=a*C i +b;Y=CPS i / CPS n; C ig =F*C i *V / M

[0028] Where: C i is the concentration of harmful elements in the standard substance digestion solution 1; a and b are curve fitting parameters, obtained by fitting the harmful element standard curve; CPS i and CPS n are the CPS counts of harmful elements and corresponding internal standard elements, respectively; F is the dilution factor; V is the solution volume, 100 mL; M is the sample mass (the mass of the standard material required to obtain 0.1 g of cations in the main associated minerals);

[0029] In step 12, the volume required for preparing the standard solution 2 with a concentration gradient is calculated according to the following formula:

[0030] V b *C b +(50-V b )*C i =50*C2

[0031] Where: V b is the volume of the required harmful element stock solution, C b is the concentration of harmful elements in the harmful element stock solution, here it is 10mg.L -1 ; C i is the concentration of harmful elements in the standard substance digestion solution 1, C2 is the concentration of harmful elements in the prepared standard solution 2, 10, 20, 50, 100, 200 and 500 μg / L.

[0032] In step 13, the formula for calculating the trace element content in each flotation product of the rare polymetallic ore is as follows:

[0033] Y y =a y *x iy +b y ; Y y =CPS iy / CPS ny ; C iy =x iy *V y / M y

[0034] Where: x iy is the concentration of harmful elements in standard solution 2; a y and b y is the curve fitting parameter, obtained by fitting the standard curve of harmful elements; CPS iy and CPS ny are the CPS counts of harmful elements and corresponding internal standard elements in standard solution 2; Ciy is the mass concentration of harmful elements in the sample; V y The volume of sample digestion solution is 2, 100 mL; M y is the sample mass, 0.1 g.

[0035] Beneficial effect: The determination method of the present invention uses the digestion solution of the standard sample of the main associated substances of the mineral to prepare the standard solution, increase the matrix concentration of the standard solution, and approach the mineral digestion solution from the two perspectives of matrix concentration and type, thereby reducing the mass spectrometry interference in the test process and improving the accuracy of the test results. Since the existing ICP-MS-based trace element accurate quantification technology uses a simple matrix standard solution for testing, the mineral needs to be diluted by a large multiple after digestion to make up for the matrix difference between it and the standard solution and reduce the mass spectrometry and non-mass spectrometry interference. However, diluting the mineral digestion solution by a high multiple will reduce the content of harmful elements, resulting in undetected results; while reducing the dilution multiple will cause the problem of low internal standard recovery rate, affecting the accuracy of the results. The present invention uses the digestion solution of the standard sample of the main associated substances of the mineral to prepare a complex matrix standard solution, which is close to the mineral digestion solution from the two perspectives of matrix concentration and type. Under the premise of similar matrix properties, the internal standard element signals of the harmful element tests in the calibration standard solution and the mineral digestion solution will show similar inhibition or enhancement effects, thereby reducing the mass spectrometry interference in the test process. By combining matrix matching with internal standard analysis, ICP-MS eliminates mass spectral and non-mass spectral interferences during ICP-MS analysis, enabling accurate determination of trace element content in complex matrices. This method is simple, easy to operate, and has broad practical application within this technical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Flow chart of the testing method of the present invention.

[0037] Figure 2 XRD spectrum of high-grade fluorite concentrate.

[0038] Figure 3 Standard curves of five harmful elements, Cu, Zn, As, Cd, and Pb, obtained using pure matrix standard solutions.

[0039] Figure 4 Standard curves of five harmful elements, Cu, Zn, As, Cd, and Pb, obtained from 500 μg / mL calcium matrix standard solution. DETAILED DESCRIPTION

[0040] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0041] The method for quantitatively determining trace harmful elements in various flotation products of rare polymetallic ores of the present invention comprises three parts: sample processing, preparation of complex matrix standard solution, and sample testing. The specific process is as follows:

[0042] Step 1: Filter, dry and grind the flotation product of the rare polymetallic ore to obtain a powder sample; the trace harmful elements in the powder sample are Cu, Zn, As, Cd and Pb.

[0043] Step 2: Weigh 0.1 g of powder sample into a polytetrafluoroethylene digestion tank, add 4 mL of aqua regia, and gently shake to mix the powder sample and aqua regia to obtain a sample to be digested. Simultaneously, prepare another blank sample 1 containing only 4 mL of aqua regia without the powder sample;

[0044] Step 3: Cover the polytetrafluoroethylene digestion tanks containing the sample to be digested and the blank sample 1 and place them in the digestion instrument. Heat them to 200 degrees and maintain for 3 hours. After heating is completed and naturally cooled, take out the digestion tank, open the lid and release the gas to obtain the sample digestion solution 1 and the blank sample 2.

[0045] Step 4: Transfer the sample digestion solution 1 and the blank sample 2 to a 100 mL volumetric flask, and use 2% ultrapure dilute nitric acid to make up the volume to obtain the sample digestion solution 2 and the blank sample 3; the 2% ultrapure dilute nitric acid is prepared by diluting ultrapure concentrated nitric acid with ultrapure water having a resistivity of ≥18 MΩ·cm.

[0046] Step 5: Perform XRD phase analysis on the powder sample obtained in step 1 to obtain the main mineral components in the powder sample;

[0047] Step 6: Based on the main minerals contained in the powder sample, purchase the corresponding high-purity standard substance, crush and grind it to obtain a -74μm fine-particle standard substance; after the standard substance is digested and diluted to a fixed volume, the element concentration in the standard substance digestion solution 1 is 1000μg / mL.

[0048] Step 7: Based on the chemical composition of the -74μm fine-grained standard material, calculate the mass of the fine-grained standard material required to obtain the cations in the main associated minerals of 0.1g powder sample;

[0049] Step 8: Digest the -74 μm fine particle standard material according to the method of steps 2 and 3, and dilute the volume to 100 mL with 2% ultrapure dilute nitric acid to obtain -74 μm standard material digestion solution 1 and blank sample 5;

[0050] Step 9: Use 2% ultrapure dilute nitric acid to dilute the harmful element stock solution in the pure matrix to prepare standard solutions 1 containing a concentration gradient of 10, 20, 50, 100, 200, and 500 μg / L of the harmful element; the volume of 2% dilute nitric acid required to prepare the standard solution 1 containing the harmful element concentration gradient is calculated according to the following formula:

[0051] (50-V k )*C b =50*C1

[0052] Where: V k is the volume of 2% dilute nitric acid required, C b is the concentration of harmful elements in the harmful element stock solution, here it is 10mg.L -1 ; C1 is the concentration of harmful elements in the prepared standard solution 1, 10, 20, 50, 100, 200 and 500 μg / L.

[0053] Step 10: Use ICP-MS to test the standard solution 1, the standard substance digestion solution 1 and the blank solution 5 in sequence using the internal standard method to obtain a standard curve of harmful elements in a simple matrix. The content C of harmful elements in the standard substance digestion solution 1 is obtained based on the standard curve of harmful elements in a simple matrix background. i , and then according to the harmful element content C i Calculate the harmful element content C of the solid sample in the standard substance ig ; The element selected for the internal standard method is 72 Ge, 115 In and 209 Bi. The content of harmful elements in the standard substance is calculated based on the standard curve of harmful elements in a simple matrix background. ig , the specific calculation formula is as follows:

[0054] Y=a*C i +b;Y=CPS i / CPS n ; C ig =F*C i *V / M

[0055] Where: C i is the concentration of harmful elements in the standard substance digestion solution 1; a and b are curve fitting parameters, obtained by fitting the harmful element standard curve; CPS i and CPS n are the CPS counts of harmful elements and corresponding internal standard elements, respectively; F is the dilution factor, which is 10 here; V is the solution volume, 50 mL; M is the sample mass, which is the mass of the standard material required to obtain 0.1 g of cations in the main associated minerals;

[0056] Step 11: Calculate the volume required to prepare the standard solution 2 with a concentration gradient based on the concentration of the harmful elements in the harmful element stock solution and the standard substance digestion solution 1;

[0057] Step 12: Use the standard substance digestion solution 1 prepared in step 9 to dilute the harmful element stock solution of the pure matrix, and prepare a standard solution 2 containing the harmful element with a concentration gradient of 10, 20, 50, 100, 200 and 500 μ; the volume required for preparing the standard solution 2 with a concentration gradient is calculated according to the following formula:

[0058] V b *C b +(50-V b )*C i =50*C2

[0059] Where: V b is the volume of the required harmful element stock solution, C b is the concentration of harmful elements in the harmful element stock solution, here it is 10mg.L -1 ; C i is the concentration of harmful elements in the standard substance digestion solution 1, C2 is the concentration of harmful elements in the prepared standard solution 2, 10, 20, 50, 100, 200 and 500 μg / L.

[0060] Step 13: Use ICP-MS to test the standard solution 2, sample digestion solution 2, and blank sample 3 using the internal standard method to obtain a standard curve for harmful elements in a complex matrix background. Calculate the trace element content in each flotation product of the rare polymetallic ore based on the standard curve. The formula for calculating the trace element content in each flotation product of the rare polymetallic ore is as follows:

[0061] Y y =a y *x iy +b y ; Y y =CPS iy / CPS ny ; C iy =x iy *V y / M y

[0062] Where: x iy is the concentration of harmful elements in standard solution 2; a y and b y is the curve fitting parameter, obtained by fitting the standard curve of harmful elements; CPS iy and CPS ny are the CPS counts of harmful elements and corresponding internal standard elements in standard solution 2; C iy is the mass concentration of harmful elements in the sample; V y The volume of sample digestion solution is 2, 100 mL; M y is the sample mass, 0.1 g.

[0063] Example: Taking the test of trace harmful elements Cu, Zn, As, Cd and Pb in high-precision fluorite flotation concentrate in a rare polymetallic ore flotation system as an example,

[0064] 1. Experimental instruments and utensils

[0065] Agilent ICP-MS 7900, X-ray diffractometer (D8 Advance), analytical balance, volumetric flasks, pipette, EDH-36 digester, polytetrafluoroethylene digestion tank, high-grade concentrated nitric acid, high-grade concentrated hydrochloric acid, ultrapure concentrated nitric acid, ultrapure water, and mixed standard solution stock solution.

[0066] 2. Experimental steps

[0067] Step 1: Sample collection and pretreatment: High-grade fluorite concentrate products are collected from the flotation system of rare metal ores, and dried, ground, and then dried to obtain a dry powder sample;

[0068] Step 2, sample digestion: Use an analytical balance to accurately weigh 0.1g of high-grade fluorite concentrate, place it in a polytetrafluoroethylene digestion tank, and add 4mL of aqua regia prepared by ultrapure hydrochloric acid and ultrapure concentrated nitric acid (volume ratio of 3:1); after the two are thoroughly mixed, cover it and place it in the digestion instrument; turn on the power and set the digestion parameters to a final temperature of 200 degrees and maintain it for 3h; after the digestion is completed, turn off the power and remove the digestion tank to cool naturally. After unscrewing the lid to release the gas, transfer the remaining liquid to a 100mL volumetric flask and add 2% ultrapure dilute nitric acid to make up the volume;

[0069] Step 3, preparation of blank solution 1: add 4 mL of aqua regia prepared by ultrapure hydrochloric acid and ultrapure concentrated nitric acid (volume ratio of 3:1) to a polytetrafluoroethylene digestion tank; cover the tank and place it in the digestion apparatus; turn on the power and set the digestion parameters to a final temperature of 200 degrees for 3 hours; after the digestion is completed, turn off the power and remove the digestion tank to cool naturally. After unscrewing the lid to release the gas, transfer the remaining liquid to a 200 mL volumetric flask and add 2% ultrapure dilute nitric acid to make up the volume;

[0070] Step 4: Sample phase composition analysis: Take 0.5g of high-grade fluorite concentrate and analyze its phase composition using XRD; the X-ray diffraction pattern of the sample is as follows: Figure 2 As shown, the main minerals of this sample are fluorite / CaF2;

[0071] Step 5. Digestion of standard substances of major minerals: Calcium carbonate was selected as the standard substance for preparing high-concentration matrix solution. It was calculated that 0.25 g of calcium carbonate was required to obtain 0.1 g of calcium element. The solution was accurately placed in a polytetrafluoroethylene digestion tank using an analytical balance, and 4 mL of aqua regia prepared by ultrapure hydrochloric acid and ultrapure concentrated nitric acid (volume ratio of 3:1) was added. After the two were thoroughly mixed, the digestion tank lid was added and placed in a digestion apparatus. The power was turned on and the digestion parameters were set to a final temperature of 200 degrees and maintained for 3 hours. After the digestion was completed, the power was turned off and the digestion tank was removed and cooled naturally. After unscrewing the lid to release the gas, the remaining liquid was transferred to a 20 mL volumetric flask and 2% ultrapure dilute nitric acid was added to the volume to obtain standard substance digestion solution 1.

[0072] Step 6, preparation of blank solution 2: add 4 mL of aqua regia prepared from ultrapure hydrochloric acid and ultrapure concentrated nitric acid (volume ratio of 3:1) to a polytetrafluoroethylene digestion tank; cover the digestion tank and place it in the digestion apparatus; turn on the power and set the digestion parameters to a final temperature of 200 degrees for 3 hours; after the digestion is completed, turn off the power and remove the digestion tank to cool naturally. After unscrewing the lid to release the gas, transfer the remaining liquid to a 100 mL volumetric flask and add 2% ultrapure dilute nitric acid to the volume to obtain standard substance digestion solution 1;

[0073] Step 7. Preparation of harmful element standard solution 1 in a simple matrix: Use a pipette to accurately weigh 0.5 mL, 2 mL, and 2.5 mL of a standard solution stock solution (10 mg / L) containing harmful elements (Cu, Zn, As, Cd, and Pb) into three clean 50 mL volumetric flasks, and add 2% ultrapure dilute nitric acid to the volume to obtain standard solutions with harmful element concentrations of 100 μg / L, 200 μg / L, and 500 μg / L; Use a pipette to accurately weigh 1 mL, 2 mL, and 5 mL of a standard solution with a harmful element concentration of 500 μg / L into three clean 50 mL volumetric flasks, and add 2% ultrapure dilute nitric acid to the volume to obtain standard solutions with harmful element concentrations of 10 μg / L, 20 μg / L, and 50 μg / L, respectively;

[0074] Step 8. Test and calculation of harmful element content in standard substances: Start the ICP-MS, set the helium input flow rate of the collision reaction cell to 5 mL / min and maintain it for 15 minutes; ignite the plasma for preheating and complete the automatic tuning, and set the test parameters according to Table 1; after completing the batch task setting, use the internal standard method to test the blank solution, simple matrix standard solution, and standard substance digestion dilution solution in sequence, and perform the spike recovery test at the same time; obtain the standard curve of harmful elements (Cu, Zn, As, Cd, and Pb are marked with the selected isotopes on the left) under the simple matrix background, as shown in the figure. Figure 3 As shown in the figure, the standard curves of five harmful elements, Cu, Zn, As, Cd and Pb, are plotted with a small graph for each element. The content of harmful elements in high-purity standard substances is then calculated according to the following formula (Table 2):

[0075] Y=a*x i +b;Y=CPS i / CPS n ; C ig =F*x i *V / M

[0076] Where x i is the concentration of harmful elements in standard solution 1; a and b are obtained by fitting the standard curve of harmful elements; CPS i and CPS n are the CPS counts of harmful elements and corresponding internal standard elements in simple matrix standard solutions; C igis the mass concentration of harmful elements in high-purity standard substances; F is the dilution factor, which is 10 here; V is the solution volume, which is 50 mL here; M is the sample mass, which is 0.25 g here.

[0077]

[0078] Table 1 ICP-MS test parameters for harmful elements in standard substance dilutions

[0079] Table 2 Mass concentration of harmful elements in standard substances

[0080]

[0081] Step 9. Preparation of harmful element standard solution 2 in a complex matrix: Based on the mass concentration of harmful elements in the standard substance calculated in step 9, calculate that after 0.1g of the standard substance is digested and diluted to 100mL, the concentrations of harmful elements Cu, Zn, As, Cd and Pb are 0μg / L, 9.20μg / L, 2.20μg / L, 0.16μg / L and 3.18μg / L respectively; use a pipette to accurately weigh 2.5mL, 2.4562mL, 2.4896mL, 2.4992mL and 2.4848mL of the mother solution (10mg / L) of the standard solution containing harmful elements (Cu, Zn, As, Cd and Pb) to five clean 50mL bottles. In a volumetric flask, the standard substance digestion solution 1 prepared in step 6 was added to the volume to obtain a complex matrix single-label solution with a concentration of 500 μg / L of Cu, Zn, As, Cd and Pb; 1 mL, 0.9548 mL, 0.9892 mL, 0.9992 mL and 0.9844 mL of the standard solution mother solution (10 mg / L) containing harmful elements (Cu, Zn, As, Cd and Pb) were accurately weighed with a pipette into five clean 50 mL volumetric flasks, and the standard substance digestion solution 1 prepared in step 6 was added to the volume to obtain a complex matrix single-label solution with a concentration of 200 μg / L of Cu, Zn, As, Cd and Pb; 0.5 mL, 0.9892 mL, 0.9992 mL and 0.9844 mL of the standard solution mother solution (10 mg / L) containing harmful elements (Cu, Zn, As, Cd and Pb) were accurately weighed with a pipette respectively. 100 μg / L complex matrix single standard solution; 5 mL, 4.1564 mL, 4.8012 mL, 4.9856 mL and 4.7120 mL of 500 μg / L complex matrix single standard solution were accurately weighed into five clean 50 mL volumetric flasks, and the standard substance digestion solution 1 prepared in step 6 was added to the volume to obtain a complex matrix single standard solution with a concentration of Cu, Zn, As, Cd and Pb of 100 μg / L .... The standard substance digestion solution 1 prepared in step 6 was diluted to volume to obtain a complex matrix single-label solution with a concentration of 50 μg / L for Cu, Zn, As, Cd and Pb; 2 mL, 1.1002 mL, 1.7878 mL, 1.9846 mL and 1.6928 mL of 500 μg / L complex matrix single-label solution were accurately weighed into five clean 50 mL volumetric flasks, and the standard substance digestion solution 1 prepared in step 6 was added to the volume to obtain a complex matrix single-label solution with a concentration of 20 μg / L for Cu, Zn, As, Cd and Pb; 1 mL, 0.0815 mL, 0.7834 mL, 0.9844 mL and 0.6928 mL were accurately weighed respectively.Pour 6864 mL of the 500 μg / L complex matrix single-label solution into five clean 50 mL volumetric flasks. Add the standard substance digestion solution 1 prepared in step 6 to the volume to obtain a complex matrix single-label solution with a concentration of 10 μg / L for Cu, Zn, As, Cd, and Pb.

[0082] Step 10, test and calculation of harmful element content in high-grade fluorite concentrate: start ICP-MS, set the helium input flow rate of the collision reaction cell to 5 mL / min and maintain it for 15 min; after igniting the plasma preheating and completing the automatic tuning, set the test parameters according to Table 2; after completing the batch task setting, use the internal standard method to test the blank solution, complex matrix standard solution and high-grade fluorite concentrate digestion solution in sequence, and perform the spike recovery experiment at the same time; obtain the standard curve of harmful elements in the complex matrix background, such as Figure 4 As shown in the figure, the standard curves of five harmful elements, Cu, Zn, As, Cd and Pb, are plotted, with a small graph for each element. The content of harmful elements in high-grade fluorite concentrate is then calculated according to the following formula (see Table 3):

[0083] Y y =a y *x iy +b y ; Y y =CPS iy / CPS ny ; C iy =x iy *V y / M y

[0084] Where x iy is the concentration of harmful elements in the solution prepared in step 2; a y and b y Obtained by fitting the standard curve of harmful elements; CPS iy and CPS ny are the CPS counts of harmful elements and corresponding internal standard elements in complex matrix standard solutions; C iy is the mass concentration of harmful elements in high-grade fluorite concentrate; V y is the volume of the solution, here it is 100mL; M y is the sample mass, which is 0.1 g here.

[0085] Table 3 Mass concentration of harmful elements in high-grade fluorite concentrate

[0086]

Claims

1. A method for quantitatively determining trace harmful elements in the flotation products of rare polymetallic ores, characterized by: It includes three parts: sample processing, preparation of complex matrix standard solution and sample testing. The specific process includes: Step 1: Filter, dry and grind the flotation product of the rare metal ore to obtain a powder sample; Step 2: Weigh 0.1 g of powder sample into a polytetrafluoroethylene digestion tank, add 4 mL of aqua regia, and gently shake to mix the powder sample and aqua regia to obtain a sample to be digested. Simultaneously, prepare another blank sample 1 containing only 4 mL of aqua regia without the powder sample; Step 3: Cover the polytetrafluoroethylene digestion tanks containing the sample to be digested and the blank sample 1 and place them in the digestion instrument. Heat them to 200 degrees and maintain for 3 hours. After heating is completed and naturally cooled, take out the digestion tank, open the lid and release the gas to obtain the sample digestion solution 1 and the blank sample 2. Step 4: Transfer the sample digestion solution 1 and blank sample 2 to a 100 mL volumetric flask and dilute to volume with 2% ultrapure dilute nitric acid to obtain sample digestion solution 2 and blank sample 3; Step 5: Perform XRD phase analysis on the powder sample obtained in step 1 to obtain the main mineral components in the powder sample; Step 6: Based on the main minerals contained in the powder sample, purchase the corresponding high-purity standard material, crush and grind it to obtain -74μm fine-grained standard material; Step 7: Based on the chemical composition of the -74μm fine-grained standard material, calculate the mass of the fine-grained standard material required to obtain the cations in the main associated minerals of 0.1g powder sample; Step 8: Digest the -74 μm fine particle standard material according to the method of steps 2-4, and dilute the volume to 100 mL with 2% ultrapure dilute nitric acid to obtain -74 μm standard material digestion solution 1 and blank sample 4; Step 9: Use 2% ultrapure dilute nitric acid to dilute the harmful element stock solution in the pure matrix to prepare standard solutions 1 containing a concentration gradient of 10, 20, 50, 100, 200 and 500 μg / L of harmful elements; Step 10: Use ICP-MS to test the standard solution 1, the standard substance digestion solution 1 and the blank solution 4 in sequence using the internal standard method to obtain a standard curve of harmful elements in a simple matrix. The content C of harmful elements in the standard substance digestion solution 1 is obtained based on the standard curve of harmful elements in a simple matrix background. i , and then according to the harmful element content C i Calculate the harmful element content C of the solid sample in the standard substance ig ; Step 11: Calculate the volume required to prepare the standard solution 2 with a concentration gradient based on the concentration of the harmful elements in the harmful element stock solution and the standard substance digestion solution 1; Step 12: dilute the harmful element stock solution of the pure matrix with the standard substance digestion solution 1 prepared in step 8, and prepare a standard solution 2 containing the harmful element with a concentration gradient of 10, 20, 50, 100, 200 and 500 μg / L; Step 13: Use ICP-MS to test the standard solution 2, sample digestion solution 2 and blank sample 3 using the internal standard method to obtain a standard curve of harmful elements in a complex matrix background, and calculate the trace element content in each flotation product of the rare polymetallic ore based on the standard curve.

2. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1, characterized in that: The 2% ultrapure dilute nitric acid is prepared by diluting ultrapure concentrated nitric acid with ultrapure water having a resistivity of ≥18 MΩ·cm.

3. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1, characterized in that: The trace harmful elements in the powder sample are Cu, Zn, As, Cd and Pb.

4. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1 is characterized in that: The elements selected for the internal standard method are 72 Ge, 115 In and 209 Bi.

5. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1 is characterized in that: After the standard substance is digested and diluted to a fixed volume, the element concentration in the standard substance digestion solution 1 is 1000 μg / mL.

6. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1 is characterized in that: In step nine, the volume of 2% dilute nitric acid required for preparing the standard solution 1 containing the concentration gradient of harmful elements is calculated according to the following formula: (50- V k )*C b =50*C1 Where: V k is the required volume of 2% dilute nitric acid, C b is the concentration of harmful elements in the harmful element stock solution, here it is 10mg.L -1 ; C1 is the concentration of harmful elements in the prepared standard solution 1, 10, 20, 50, 100, 200 and 500 μg / L.

7. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1, wherein: step 10 The content of harmful elements in the standard substance C is calculated based on the standard curve of harmful elements in a simple matrix background. ig , the specific calculation formula is as follows: Y=a*C i +b; Y=CPS i / CPS n ; C ig =F* C i *V / M Where: C i is the concentration of harmful elements in the standard substance digestion solution 1; a and b are curve fitting parameters, obtained by fitting the harmful element standard curve; CPS i and CPS n are the CPS counts of harmful elements and corresponding internal standard elements, respectively; F is the dilution factor; V is the solution volume, 50 mL; M is the sample mass, that is, the mass of the standard substance required to obtain 0.1 g of cations in the main associated minerals.

8. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1, characterized in that: In step 12, the volume required for preparing the standard solution 2 with a concentration gradient is calculated according to the following formula: V b *C b +(50- V b )*C i =50*C2 Where: V b is the volume of the required harmful element stock solution, C b is the concentration of harmful elements in the harmful element stock solution, here is 10mg.L -1 ; C i is the concentration of harmful elements in the standard substance digestion solution 1, C2 is the concentration of harmful elements in the prepared standard solution 2, 10, 20, 50, 100, 200 and 500 μg / L.

9. The method for quantitatively determining trace harmful elements in each flotation product of a rare polymetallic ore according to claim 1, characterized in that: In step 13, the formula for calculating the trace element content in each flotation product of the rare polymetallic ore is as follows: Y y =a y *x iy +b y ; Y y =CPS iy / CPS ny ; C iy =x iy *V y / M y Where: x iy is the concentration of harmful elements in standard solution 2; a y and b y is the curve fitting parameter, obtained by fitting the standard curve of harmful elements; CPS iy and CPS ny are the CPS counts of harmful elements and corresponding internal standard elements in standard solution 2; C iy is the mass concentration of harmful elements in the sample; V y The volume of sample digestion solution is 2, 100 mL; M y is the sample mass, 0.1 g.

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