A method for detecting gallium, vanadium and phosphorus in coal and gangue

Abstract

The present application belongs to the technical field of element analysis, and provides a detection method for measuring gallium, vanadium and phosphorus in coal and gangue, which adopts an HNO3-H2SO4-HF-H2O2 oxidation digestion system, can effectively remove organic matter in the coal and gangue samples and can completely digest silicon-containing minerals, and uses hydrochloric acid as a medium to resuspend the sample, prepare a sample solution to be measured, and establish an analysis method for measuring vanadium, phosphorus and gallium based on an acid dissolution and oxidation method pretreatment technology ICP-AES method. The method eliminates the ashing step of the coal sample in the traditional process, avoids the loss of volatile elements in the ashing process, effectively solves the problem that the above-mentioned three elements in the coal and gangue cannot be simultaneously pretreated and measured, simplifies the analysis process, improves the analysis efficiency, is convenient for data comparison, and is suitable for batch sample analysis with complex matrix and wide content range.

Description

Technical Field

[0001] This invention belongs to the field of elemental analysis technology, specifically relating to a method for determining gallium, vanadium, and phosphorus in coal and gangue. Background Technology

[0002] Coal and gangue belong to a special type of sedimentary organic rock, and their formation often involves the generation and enrichment of various trace elements. Among these, Ga and V, under specific geological and geochemical conditions, can form strategic coal-bearing metallic minerals and are considered beneficial trace elements, serving as important raw materials for the electronics, steel, and chemical industries. While phosphorus (P) content in coal is usually low, it enters the atmosphere, water bodies, and soil through various pathways during coal mining, transportation, and utilization, directly harming human health and causing environmental pollution and ecological damage. Furthermore, P from phosphorus-rich coal can cause brittleness in steel after entering coke, classifying it as a harmful trace element. Therefore, Ga, V, and P are essential parameters for coal quality evaluation and comprehensive coal utilization. MT / T 1090-2008, "Specification for Coal Quality Evaluation in Coal Resource Exploration," clearly stipulates the analytical testing ratios of Ga, V, and P in coal at each exploration stage. Accurate determination of Ga, V, and P content in coal and gangue provides crucial data support for assessing the development potential of metallic mineral resources and conducting ecological and environmental protection assessments.

[0003] Coal and gangue samples have high organic matter content. If the organic matter or carbonaceous substances are not completely decomposed during pretreatment, they can easily adsorb or encapsulate the target elements, leading to lower measurement results. Furthermore, undecomposed black residue may cause signal drift, sample introduction system blockage, or flameout during instrument analysis. Currently, the standard methods for determining Ga, V, and P are GB / T 8208-2007, GB / T 19226-2003, and GB / T 216-2003, respectively. All of these methods require high-temperature ashing at different temperatures, followed by multiple sample dissolutions and individual spectrophotometric determinations. These methods involve cumbersome ashing processes and complex operations, and the high-temperature process may lead to the volatilization loss of P, making it difficult to meet the high-efficiency analytical requirements for simultaneous determination of multiple elements in a single pretreatment. Reported methods for digesting coal and gangue include ashing-alkali fusion, ashing-acid dissolution, microwave digestion, and high-pressure closed acid dissolution. Among these methods, the alkali fusion method exhibits a significant matrix effect, often requiring sample separation and enrichment, making the process cumbersome. The ashing-acid dissolution method is prone to phosphorus loss or contamination. While high-pressure closed-loop acid dissolution and microwave digestion can avoid the loss of volatile elements during ashing, coal samples have complex compositions and high organic matter content; using only microwave digestion may result in incomplete extraction of some elements, affecting the accuracy of the results. Furthermore, microwave digestion requires strict temperature control, and the digestion vessel is prone to deformation or even explosion, posing a high risk and making it unsuitable for batch sample processing. The high-pressure closed-loop acid dissolution method also has a long process and is not suitable for large-scale sample processing. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for determining gallium, vanadium, and phosphorus in coal and gangue.

[0005] A method for determining gallium, vanadium, and phosphorus in coal and gangue includes the following steps: An HNO3-H2SO4-HF-H2O2 oxidative digestion system was used to remove organic matter from the sample and digest silicon-containing minerals. Following this, hydrochloric acid was used as the medium for hydrochloric acid dissolution and oxidation treatment to obtain the test solution. The volume ratio of HNO3, H2SO4, HF, and H2O2 was 10~20:0.5~2:5~15:1~10; the mass-volume ratio of the sample to the HNO3 was 0.1g:10mL~20mL. The contents of vanadium, phosphorus, and gallium in the test solution were determined using the ICP-AES method.

[0006] This invention utilizes HNO3 and H2SO4 to decompose organic matter in coal and gangue, followed by complete decomposition of the sample using a mixed acid system composed of HF, HNO3, and H2SO4. After removing residual organic matter by adding H2O2, the sample is dissolved and oxidized with hydrochloric acid to prepare the test solution. By controlling the amounts of HNO3, H2SO4, HF, and H2O2 added, the digestion temperature, the selection of analytical lines, and the influence of interfering factors on the determination results, a novel method for the simultaneous determination of Ga, V, and P in coal and gangue using ICP-AES was established. This method facilitates result comparison and is suitable for batch sample analysis.

[0007] In another preferred embodiment, the specific process of obtaining the test liquid is as follows: The sample is moistened with ethanol, and then HNO3 is added and allowed to stand for 12-24 hours. HNO3 is the main oxidant used to decompose organic matter. The 12-24 hour standing time allows nitric acid to fully penetrate the sample, initially oxidizing and decomposing easily decomposed organic matter, and converting existing sulfides into sulfates, creating a stable and homogeneous reaction matrix for subsequent steps. This standing step is crucial for the complete digestion of complex solid samples.

[0008] Add H₂SO₄ and heat at 100℃~130℃ for 1-2 hours, then raise the temperature to 150℃~170℃ until brownish-yellow fumes are emitted, then stop heating and cool. H₂SO₄ is a strong dehydrating and carbonizing agent and serves as the high-temperature reaction medium. In this invention, sulfuric acid is heated at 100~130℃; its strong dehydrating properties cause the water in the sample to evaporate rapidly and carbonize the organic matter. The subsequent heating to 150~170℃ until brownish-yellow fumes are emitted indicates that the nitric acid oxidation reaction is still proceeding vigorously. At this stage, the high boiling point of sulfuric acid (~338℃) ensures that the system can continue the nitration / oxidation reaction at high temperatures, thoroughly destroying the skeletal structure of the organic matter. The timing of sulfuric acid addition and temperature control are crucial to ensuring that the organic matter is deeply destroyed rather than simply dissolved.

[0009] Add HF, heat to 100℃~120℃ and hold for 20min~40min, then heat to 200℃~250℃ for decomposition until no white fumes are emitted, then cool. HF is added after the sample has been treated with H2SO4 at high temperature and is in an inorganic residue state. First, at 100~120℃, HF reacts initially with silicates to form SiF4, then the temperature is raised to 200~250℃ until sulfuric acid fumes, ensuring complete reaction of HF and thorough removal of SiF4 and excess HF until no white fumes are emitted. This sequence avoids interference from fluorocarbons that may result from premature contact between HF and organic matter, and also prevents HF from inhibiting subsequent oxidation. The two-step temperature increase achieves efficient, safe, and complete removal of HF.

[0010] After adding H₂O₂ and heating at 120℃~180℃ for 15-25 minutes to completely evaporate the solution, HCl is added, and the mixture is heated to boiling to obtain a concentrated solution. After cooling, the solution is diluted to volume with water to obtain the digested test solution. After HF removal of silicon and acid, extremely stable tiny carbon particles or difficult-to-oxidize carbonaceous residues may remain in the system. Adding H₂O₂ and heating at 120~180℃ at this point allows the strong oxidizing hydroxyl radicals generated by its decomposition to effectively attack these residues, achieving complete removal of organic matter. This step, placed after HF, avoids potentially violent side reactions between H₂O₂ and HF, and concentrates its oxidizing power on the most stubborn residues. Finally, adding HCl and boiling aims to convert the metal oxides and salts formed after digestion, especially sulfates and fluorides, into soluble chlorides or chloride complexes, ensuring that all target elements, especially those that may form insoluble sulfates or fluorides, are completely transferred into the solution, avoiding loss due to precipitation.

[0011] In another preferred embodiment, if obvious black particles are still present during the heating process with added H2SO4, HNO3 is added, and heating continues until brownish-yellow fumes are emitted and no black particles remain.

[0012] In another preferred embodiment, the RF power of the ICP-AES method is 1150W, the cooling gas flow rate is 13L / min, the auxiliary gas flow rate is 0.5L / min, and the atomizing gas flow rate is 0.7L / min.

[0013] In another preferred embodiment, the processes of adding HNO3, H2SO4, and H2O2 are all carried out in a closed environment, while the process of adding HF is carried out in a non-closed environment.

[0014] In another preferred embodiment, in the ICP-AES method, the analytical spectral line of gallium is 294.364{114}nm, the analytical spectral line of vanadium is 292.402{115}nm, and the analytical spectral line of phosphorus is 214.914{457}nm.

[0015] In another preferred embodiment, the ICP-AES method has an injection pump speed of 50 r / min, a vertical observation height of 12 mm, an exposure time of 15 s, and an integration time of 15 s.

[0016] In another preferred embodiment, the sample is coal and gangue.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention employs an HNO3-H2SO4-HF-H2O2 oxidation digestion system, which effectively removes organic matter from coal and gangue samples and achieves complete decomposition of silicon-containing minerals. The resulting solution is then prepared by acid re-dissolution and extraction. An analytical method for simultaneous determination of Ga, V, and P using acid dissolution oxidation to remove organic matter, followed by ICP-AES, is established. This method eliminates the ashing step in traditional processes, avoiding the loss of volatile elements during ashing. It effectively solves the problem of simultaneous pretreatment and determination of Ga, V, and P in coal and gangue, simplifying the analytical process, improving analytical efficiency, facilitating data comparison, and is suitable for batch sample analysis with complex matrices and wide content ranges. It can provide reliable data support for the accurate and efficient assessment of Ga, V, and P content in coal-based resources. Using the t-test calculations of the method in this invention, the t-values ​​of the results and the results determined by national standards are all less than the critical value at a 95% confidence level, showing no significant difference, and the detection limit is as low as 0.29 μg / g.

[0018] The pretreatment method provided by this invention is simpler than traditional methods and avoids the problems of cumbersome traditional high-temperature ashing methods, the loss of some phosphorus due to high temperatures, and the impact on the accuracy of gallium, vanadium, and phosphorus analysis results. A detection method is established for the simultaneous determination of gallium, vanadium, and phosphorus in coal and gangue by acid dissolution and oxidation to remove organic matter, followed by inductively coupled plasma atomic emission spectrometry (ICP-AES). This solves the problem that current methods require gallium, vanadium, and phosphorus to be ashed at different temperatures and then measured separately using spectrophotometers, which is cumbersome, has high detection limits, and is prone to phosphorus volatilization loss due to high temperatures, making it impossible to achieve simultaneous determination of multiple elements in a single pretreatment. Attached Figure Description

[0019] Figure 1 This is the standard curve for Ga.

[0020] Figure 2 This is the standard curve for the V element.

[0021] Figure 3 This is the standard curve for element P.

[0022] Figure 4 The spectrum of Ga in GBW11115 solution is shown below the optimal analytical line.

[0023] Figure 5The spectrum of element V in GBW11115 test solution is shown below the optimal analytical line.

[0024] Figure 6 The spectrum of P element in GBW11115 test solution is shown below the optimal analytical line. Detailed Implementation

[0025] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0026] Instruments and equipment: iCAP 6300 inductively coupled plasma atomic emission spectrometer (Thermo Scientific); AL204 electronic balance (Mettler-Toledo Instruments (Shanghai) Co., Ltd.); SD46-1 temperature-controlled intelligent heating plate (Tianjin Tuozhiming Experimental Instrument Equipment Co., Ltd.); sample sieve: nylon material, 0.2 mm aperture.

[0027] Inductively coupled plasma atomic emission spectrometry (ICP-AES) possesses advantages such as high sensitivity, low detection limit, wide linear range, low interference, and suitability for simultaneous determination of multiple elements, and has been widely used for the determination of trace elements in geological samples. However, few studies have reported methods for directly weighing samples, using open-air acid dissolution and oxidation to remove organic matter, and then combining this with ICP-AES for the simultaneous determination of Ga, V, and P in coal and gangue. Therefore, establishing a simple, rapid, efficient method that can digest samples in a single step and achieve simultaneous determination of Ga, V, and P is of significant practical importance.

[0028] HNO3, a strong oxidizing agent, can destroy the organic matter in coal and gangue and dissolve most of the metal elements, allowing them to enter the solution. H2SO4, a high-boiling-point, highly oxidizing reagent, can react fully with the carbon matrix in coal and gangue, thus ensuring more complete sample dissolution. HF, when mixed with strong acids HNO3 and H2SO4 and heated, can completely destroy the stable silicate lattice, allowing the analyte elements to enter the solution. H2O2 itself has a certain oxidizing ability and can directly react with some easily oxidized organic compounds, thereby removing them. Therefore, this invention selects the HNO3-H2SO4-HF-H2O2 oxidative digestion system for the digestion of coal and gangue.

[0029] Common methods for removing large amounts of organic matter from coal and gangue include high-temperature incineration and strong oxidant decomposition. This invention uses a strong oxidant method to remove organic matter from coal. Specifically, the sample is weighed directly, and HNO3, which can destroy organic matter and form highly soluble nitrates with most of the metal elements in coal and gangue, is used as the oxidant. The sample is left to stand at room temperature for 12-24 hours, and then the oxidant H2SO4 is added to react at 100-160°C to destroy the organic matter, thereby reducing the impact of organic matter on the subsequent high-temperature digestion process. After the sample is evaporated to dryness, HF is added to form a mixed acid system with the remaining HNO3 and H2SO4. By controlling the temperature and heating for digestion, the quartz component in the coal or gangue can be volatilized and escaped as SiF4. The addition of H2SO4 can raise the temperature, making it easier to completely decompose the sample and remove the remaining HF. The addition of H2O2 can further completely oxidize the residual organic matter. To prevent samples such as gangue or those with low organic content from being difficult to completely dissolve in H2O2, hydrochloric acid is used for redissolution, ensuring complete dissolution of the sample in the test solution and thus guaranteeing a low blank value in the measurement results. Since H2O2 only introduces hydrogen and oxygen, it prevents the introduction of the analyte elements. Furthermore, this digestion system avoids the loss of phosphorus due to high-temperature ashing and the safety risks associated with using HClO4.

[0030] The volume ratio of HNO3, H2SO4, HF, and H2O2 should be 10~20:0.5~2:5~15:1~10. Insufficient reagent addition will result in incomplete decomposition of organic matter, and coal and gangue samples will be difficult to completely dissolve in the test solution, leading to lower results for the measured elements Ga, V, and P. Excessive reagent addition will prolong the dissolution time and reduce work efficiency.

[0031] The following is a detailed description of a method for determining gallium, vanadium, and phosphorus in coal and gangue.

[0032] The experiment was designed using an L(3³) orthogonal array. In this embodiment, two standard substances (GBW11139 and GSR-1) were used as samples to test the decomposition effect. The orthogonal experimental design table is shown in Table 1.

[0033] Table 1 Orthogonal Experimental Design Table Example 1 Accurately weigh 0.10 g (accurate to 0.0001 g) of sample into a 50 mL polytetrafluoroethylene (PTFE) beaker with a lid. Wet the sample with approximately 2 drops of anhydrous ethanol using a dropper, add 10 mL of HNO3, cover, and let stand overnight at 20°C. The next day, add 0.5 mL of H2SO4, cover, and place on a temperature-controlled hot plate, heating at 120°C for 1.5 h. Then raise the temperature to 160°C and continue heating until just beginning to emit brownish-yellow fumes. If obvious black particles remain in the beaker, indicating incomplete decomposition of organic matter, add 5 mL of HNO3 and heat again until brownish-yellow fumes are emitted. After cooling, add 5 mL of HF, leave the beaker uncovered, and continue heating to 110°C for 30 min, then raise the temperature to 220°C to decompose the sample until all white fumes are emitted.

[0034] After cooling, add 1 mL of H₂O₂, cap, and heat on a 150°C hot plate for about 20 minutes. Remove the cap and evaporate the solution to near dryness. Add 5 mL of HCl, heat to boiling until the solution volume is reduced to 2–3 mL and becomes clear, then remove and cool. Transfer the solution to a 25 mL volumetric flask, dilute to the mark with water, shake well, and allow to stand until clear to obtain the digested test solution.

[0035] Example 2 The difference between this embodiment and Embodiment 1 is that the amount of HF added is adjusted to 10 mL and the amount of H2O2 added is 5 mL, while the rest of the process is the same as in Embodiment 1.

[0036] Example 3 The difference between this embodiment and Embodiment 1 is that the amount of HF added is adjusted to 15 mL and the amount of H2O2 added is 10 mL, while the rest of the process is the same as in Embodiment 1.

[0037] Example 4 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 1 mL, the amount of HF added is 10 mL, and the amount of H2O2 added is 1 mL. All other processes are the same as in Embodiment 1.

[0038] Example 5 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 1 mL, the amount of HF added is 15 mL, and the amount of H2O2 added is 5 mL. All other processes are the same as in Embodiment 1.

[0039] Example 6 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 1 mL, the amount of HF added is 5 mL, and the amount of H2O2 added is 10 mL. All other processes are the same as in Embodiment 1.

[0040] Example 7 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 2 mL, the amount of HF added is 15 mL, and the amount of H2O2 added is 1 mL. All other processes are the same as in Embodiment 1.

[0041] Example 8 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 2 mL, the amount of HF added is 5 mL, and the amount of H2O2 added is 5 mL. All other processes are the same as in Embodiment 1.

[0042] Example 9 The difference between this embodiment and Embodiment 1 is that the amount of H2SO4 added is adjusted to 2 mL, the amount of HF added is 10 mL, and the amount of H2O2 added is 10 mL. All other processes are the same as in Embodiment 1.

[0043] The contents of target elements Ga, V, and P in the digestion solution were detected by ICP-AES according to the working conditions in Table 2. The results are shown in Table 3 below.

[0044] Table 2 ICP-AES Operating Conditions Table 3. Experimental results of orthogonal experiments for GBW11139 and GSR-1 Table 4 Range Analysis of Orthogonal Experiments in GBW11139 Table 5 Range Analysis of GSR-1 Orthogonal Experiment Note: K is the sum of the results of the factorial experiments; k is the average of the experimental results.

[0045] Range analysis of the orthogonal experimental results for GBW11139 and GSR-1 (Tables 4 and 5) shows that for both the coal standard sample GBW11139 and the rock standard sample GSR-1 (used to simulate gangue with extremely low organic matter content), factor A, the volume of H2SO4, has the greatest influence. In actual testing of coal and gangue samples, due to their high organic matter content, it is necessary to ensure sufficient H2O2 addition to completely remove residual organic matter. The experimental results for GSR-1 indicate that when the HF addition is 10 mL or 15 mL, the measured values ​​of Ga, V, and P are consistent with the accepted values, indicating that 10 mL of HF is sufficient for complete sample decomposition. Therefore, considering the characteristics of both samples, the order of importance of the key acid reagents affecting the digestion effect is determined to be ABC, i.e., H2SO4 volume > H2O2 volume > HF volume.

[0046] Based on the analysis of k1, k2, and k3 values ​​of Ga, V, and P, and combined with visual observation of the clarity of the digestion solution: After adding H2O2 and heating GBW11139, the solutions from Examples 5, 6, 8, and 9 were visually pale yellow and clear, while the solutions from other examples were darker in color, less clear, and contained varying degrees of black particles. After adding H2O2 and heating GSR-1, the solutions from Examples 4, 5, 7, and 9 were visually pale yellow and clear, while the solutions from other examples showed varying degrees of precipitation. The determined optimal digestion condition combination was A2B2C2, i.e., 1 mL H2SO4, 5 mL H2O2, and 10 mL HF.

[0047] Example 10 1. Preparation of the standard working solution series: First, the single-element standard stock solutions of Ga, V, and P were serially diluted with 10% (V / V) hydrochloric acid to prepare mixed standard working solutions with mass concentrations of 10 μg / mL and 100 μg / mL, respectively. Then, equal volumes of the above mixed standard working solutions were added to six 100 mL volumetric flasks, numbered S0, S1, S2, S3, S4, and S5, respectively, and diluted to the mark with 10% hydrochloric acid by mass. The solutions were then shaken well to prepare the standard working solution series. The mass concentrations of each element are shown in Table 6.

[0048] Table 6. Mass concentrations of each element in the standard solution series. 2. Calibration curve and detection limit Under the established ICP-AES operating conditions (see Table 2), a series of mixed standard solutions of Ga, V, and P were measured. Calibration curves were plotted with the mass concentration of each element on the x-axis and the corresponding emission spectral intensity on the y-axis (e.g., ...). Figures 1-3 According to HJ 168-2020 "Technical Guidelines for the Development of Standards for Environmental Monitoring Analytical Methods", seven parallel determinations were performed on the sample blank solution, and the standard deviation (s) of the determination results was used as the criterion. s The limit of detection (LOD) was calculated, and the limit of quantitation (LOQ) was calculated by multiplying the LOD by 4. The determination range, linear regression equation, correlation coefficient, LOD and LOQ results for each element are listed in Table 7.

[0049] Table 7 Calibration curves and detection limits 3. Precision test and comparison test Two coal samples (1# and 2#) and one gangue sample (3#) from the No. 3 mining area of ​​Taigemiao North District, Dongsheng Coalfield, Inner Mongolia Autonomous Region, were selected and compared with the current standard methods (GB / T 8208-2007, GB / T19226-2003 and GB / T 216-2003) using the method provided in this invention.

[0050] Accurately weigh 0.10 g (accurate to 0.0001 g) of sample into a 50 mL polytetrafluoroethylene (PTFE) beaker with a lid. Wet the sample with approximately 2 drops of anhydrous ethanol using a dropper, add 10 mL of HNO3, cover, and let stand overnight at 20°C. The next day, add 1 mL of H2SO4, cover, and place on a temperature-controlled hot plate, heating at 120°C for 1.5 h. Then raise the temperature to 160°C and continue heating until just beginning to emit brownish-yellow fumes. If obvious black particles remain in the beaker, indicating incomplete decomposition of organic matter, add 5 mL of HNO3 and heat again until brownish-yellow fumes are emitted. After cooling, add 10 mL of HF, leave the beaker uncovered, and continue heating to 110°C for 30 min, then raise the temperature to 220°C to decompose the sample until all white fumes are emitted.

[0051] After cooling, add 5 mL of H₂O₂, cap, and heat on a 150°C hot plate for approximately 20 minutes. Remove the cap and evaporate the solution to near dryness. Add 5 mL of HCl, heat to boiling until the solution volume remains at 2–3 mL and is clear, then remove and cool. Transfer the solution to a 25 mL volumetric flask, dilute to the mark with water, shake well, and allow to stand until clear before analysis. Prepare a blank sample solution for the experiment. Then, analyze the sample according to the instrument conditions in Table 2.

[0052] The results are shown in Table 8. A t-test was performed to calculate the difference between the results obtained from the two methods. t The values ​​are all less than the critical value at a confidence level of 95% (t). 0.05,7 = 2.447), indicating that there is no significant difference between the two methods.

[0053] Table 8 Comparison of measurement results for different digestion methods on actual samples. 4. Spectral line analysis and interference analysis Selecting appropriate analytical spectral lines is crucial to ensuring the accuracy of measurement results. This invention simultaneously measures the spectral lines of Ga, V, and P elements in calibration curves, blanks, and GBW11115 test solutions at different wavelengths. Figure 4 , Figure 5 and Figure 6As shown, by comparing the background profiles and intensity values ​​of each major spectral line, and based on the principles of low background, flat background position, no interfering small peaks, sufficient distance from adjacent spectral peaks, average background intensity consistent with the background at the spectral peak, moderate intensity, small interference and good stability, Ga (294.364{114}nm), V (292.402{115}nm), and P (214.914{457}nm) were finally selected as the analytical spectral lines for Ga, V, and P.

[0054] This invention employs an HNO3-H2SO4-HF-H2O2 oxidative digestion system, which effectively removes organic matter from coal and gangue samples and achieves complete decomposition of silicon-containing minerals. The resulting solution is then prepared by HCl extraction. A method for simultaneous determination of Ga, V, and P using acid dissolution oxidation to remove organic matter, followed by ICP-AES, has been established. This method eliminates the ashing step in traditional processes, avoiding the loss of volatile elements during ashing. It effectively solves the problem of simultaneous pretreatment and determination of these three elements in coal and gangue, simplifying the analytical process, improving analytical efficiency, facilitating data comparison, and is suitable for batch sample analysis with complex matrices and wide content ranges. It can provide reliable data support for the accurate and efficient assessment of Ga, V, and P content in coal-based resources.

[0055] Compared with traditional coal analysis methods, the oxidative acid dissolution pretreatment system used in this invention provides a technical reference for the simultaneous analysis of multiple trace and rare dispersed elements in coal and gangue. The method provided by this invention is simpler than traditional methods and avoids the problems of cumbersome processes and the loss of phosphorus due to high temperatures in traditional high-temperature ashing methods, which affect the accuracy of gallium, vanadium, and phosphorus analysis results. This invention establishes a method for simultaneously determining gallium, vanadium, and phosphorus in coal and gangue using inductively coupled plasma atomic emission spectrometry (ICP-AES) after acid dissolution and oxidation to remove organic matter. This solves the current problem that gallium, vanadium, and phosphorus require separate high-temperature ashing at different temperatures followed by separate spectrophotometric measurements, which is cumbersome, has high detection limits, and is prone to phosphorus volatilization loss due to high temperatures, making it impossible to achieve simultaneous determination of multiple elements in a single pretreatment.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining gallium, vanadium, and phosphorus in coal and gangue, characterized in that, Includes the following steps: An HNO3-H2SO4-HF-H2O2 oxidative digestion system was used to remove organic matter from the sample and digest silicon-containing minerals. Following this, hydrochloric acid was used as the medium for hydrochloric acid dissolution and oxidation treatment to obtain the test solution. The volume ratio of HNO3, H2SO4, HF, and H2O2 was 10~20:0.5~2:5~15:1~10; the mass-volume ratio of the sample to the HNO3 was 0.1g:10mL~20mL. The contents of vanadium, phosphorus, and gallium in the test solution were determined using the ICP-AES method.

2. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 1, characterized in that, The specific process for obtaining the test solution is as follows: The sample was moistened with ethanol, HNO3 was added and allowed to stand for 12-24 hours, then H2SO4 was added and heated at 100-130℃ for 1-2 hours. The temperature was then increased to 150-170℃ and the heating was stopped when brownish-yellow fumes were emitted. The sample was then cooled. After cooling, add HF, heat to 100℃~120℃ and hold for 20min~40min, then heat to 200℃~250℃ until no white smoke is emitted, and then cool. After cooling, add H2O2 and heat at 120℃~180℃ for 15min~25min. Then add HCl and heat to boiling to obtain a concentrated solution. After cooling, dilute to volume with water to obtain the digested test solution.

3. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 1, characterized in that, If obvious black particles are still present during the heating process after adding H2SO4, add HNO3 and heat until brownish-yellow fumes are emitted and no black particles remain.

4. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 3, characterized in that, The RF power of the ICP-AES method is 1150W, the cooling gas flow rate is 13L / min, the auxiliary gas flow rate is 0.5L / min, and the atomizing gas flow rate is 0.7L / min.

5. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 2, characterized in that, The processes of adding HNO3, H2SO4, and H2O2 are all carried out in a closed environment, while the process of adding HF is carried out in a non-closed environment.

6. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 1, characterized in that, In the ICP-AES method, the analytical spectral line for gallium is 294.364 nm, the analytical spectral line for vanadium is 292.402 nm, and the analytical spectral line for phosphorus is 214.914 nm.

7. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 1, characterized in that, The specific spectrometer parameters for the ICP-AES method are as follows: The injection pump speed was 50 r / min, the vertical observation height was 12 mm, the exposure time was 15 s, and the integration time was 15 s.

8. The method for determining gallium, vanadium, and phosphorus in coal and gangue according to claim 1, characterized in that, The sample is coal or gangue.

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