Method for measuring quantity of elements in lithium ore by closed acid-soluble system

Abstract

The invention belongs to the technical field of geological sample analysis and detection, and particularly discloses a method for measuring the amount of each element of lithium ore in a closed acid-soluble system, and the method comprises the following steps: pretreating the lithium ore; the pretreated lithium ore is weighed and put into a closed sample dissolving device, hydrofluoric acid and purified nitric acid are sequentially added, and the closed sample dissolving device is closed; carrying out heat preservation on the closed sample dissolving device twice to obtain a test solution; and measuring the test solution by using an inductively coupled plasma mass spectrometer to obtain a working curve, and calculating the content of the analysis element in the sample solution by using the working curve. The method for determining the amount of each element in the lithium ore by adopting the closed acid-soluble system has the characteristics of simplicity in operation, high efficiency and good stability, realizes simultaneous determination of the amount of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium and rare earth elements in the large-batch lithium ore, and further provides a reference for determination of main trace elements in the lithium ore.

Description

Technical Field

[0001] This invention belongs to the field of geological sample analysis and testing technology, specifically relating to a method for determining the amount of various elements in lithium ore using a closed acid-soluble system. Background Technology

[0002] Lithium ore, as an emerging strategic resource, is an important mineral for responding to major international conflicts and ensuring national resource security. Currently, lithium is mainly used in controlled nuclear fusion, new energy batteries, and the nuclear industry. Especially under the current national framework of vigorously promoting new energy, lithium plays an irreplaceable role. With the deepening of the national new round of mineral exploration breakthroughs, mineral geological surveys, detailed surveys, and explorations have generated a large number of ore samples. There is an urgent need to establish a rapid, accurate, and efficient analytical method for determining the major elements and various associated elements in lithium ore, thereby guiding mineral exploration activities. This is of great significance.

[0003] Existing methods for the quantitative analysis of lithium, rubidium, cesium, and associated elements such as beryllium, strontium, niobium, tantalum, zirconium, hafnium, and rare earth elements in lithium ore have significant shortcomings. Lithium, rubidium, and cesium are mostly analyzed using atomic absorption spectrometry; zirconium and hafnium using X-ray fluorescence spectrometry; rare earth elements using inductively coupled plasma optical emission spectrometry (ICP-OES); beryllium using catalytic polarography; and niobium and tantalum using colorimetric methods. Each method requires separate operation for each element, making simultaneous multi-element determination impossible. Furthermore, these digestion techniques are not only cumbersome and limited to a single element, but also inefficient, consuming large amounts of acids and alkalis. Therefore, finding a pollution-free or low-pollution sample digestion technique that enables simultaneous multi-element determination in lithium ore is urgently needed.

[0004] The closed digestion method uses a small amount of acid and employs high temperature and pressure to raise the boiling point of the acid inside the vessel, thereby improving the sample decomposition ability and efficiency. However, existing closed digestion methods have shortcomings: some studies use high-pressure closed digestion methods optimized only for lithium; or in the determination of niobium and tantalum, aqua regia-tartaric acid extraction salt solution is added to achieve accurate determination of niobium and tantalum, but the addition of tartaric acid increases the viscosity of the test solution, leading to reduced stability of the sample measured by the instrument, thus affecting the precision of the determination.

[0005] Because existing closed acid dissolution methods for the simultaneous determination of Li, Rb, Cs, Be, Sr, Nb, Ta, Zr, Hf, and rare earth elements in lithium ore lack a unified and efficient technical solution regarding the digestion system, temperature, time, and selection of resolution acids, especially for incomplete dissolution of high-grade metamorphic lithium ores, the problem remains unresolved. Therefore, there is a need in this field to develop a closed acid dissolution system for determining the amounts of various elements in lithium ore that can effectively solve the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the amount of various elements in lithium ore using a closed acid-soluble system. This method is characterized by its simple operation, high efficiency, and good stability. It enables the simultaneous determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium, and rare earth elements in large batches of lithium ore, thereby providing a reference for the determination of major and trace elements in lithium ore.

[0007] To achieve the above objectives, the present invention provides a method for determining the amounts of various elements in lithium ore using a closed acid-soluble system, comprising the following steps:

[0008] Step S1: Pre-treat the lithium ore;

[0009] First, dry the lithium ore at a constant temperature of 85-95℃ for 1.5-2 hours to remove surface adsorbed water, then raise the temperature to 110-115℃ and dry at a constant temperature for 0.5-1 hours to remove crystal water. After cooling, place it in a desiccator for later use to avoid secondary moisture absorption of the sample.

[0010] Step S2: Weigh the pretreated lithium ore into a sealed sample dissolving container, and add hydrofluoric acid and purified nitric acid in sequence, and then seal the sample dissolving container.

[0011] Since lithium ore is mostly concentrated in silicate rocks with relatively high silicon content, the digestion system with added hydrofluoric acid can destroy the silicon-oxygen lattice, allowing the rare metals encased in the lattice to dissolve completely. Furthermore, hydrofluoric acid reacts with silicon dioxide to form volatile silicon tetrafluoride, which can evaporate and escape during heating.

[0012] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0013] Step S4: Transfer the test solution to a plastic volumetric flask, bring the volume to the mark, shake well, and then use an inductively coupled plasma mass spectrometer to obtain the working curve. Use the working curve to calculate the content of the analyte in the sample solution.

[0014] Preferably, the sealed sample dissolution device includes a stainless steel outer shell and a polytetrafluoroethylene inner vessel; wherein, the stainless steel outer shell has a pressure resistance ≥10MPa and the polytetrafluoroethylene inner vessel has a temperature resistance ≥300℃;

[0015] Step S2 specifically involves weighing the pretreated lithium ore into a polytetrafluoroethylene inner container, adding hydrofluoric acid and purified nitric acid in sequence, letting it stand for 5-8 minutes to allow the reagents to fully pretreat the lithium ore, then covering the polytetrafluoroethylene inner container with a lid and sealing it with a stainless steel outer casing.

[0016] Preferably, in step S2, 0.04-0.12 g of pretreated lithium ore is weighed; 1.5-2 mL of hydrofluoric acid is added, wherein the mass fraction of hydrofluoric acid is 40%; and 0.8-1 mL of purified nitric acid is added, wherein the purity of the purified nitric acid is ≥99.999%.

[0017] Preferably, in step S2, when the Li2O content in the lithium ore is >5%, 0.04-0.08g of the pretreated lithium ore is weighed; when the Li2O content in the lithium ore is ≤5%, 0.08-0.12g of the pretreated lithium ore is weighed.

[0018] When the silicon content in the lithium ore is >20%, add 1.8-2 mL of hydrofluoric acid; when the silicon content in the lithium ore is ≤20%, add 1.5-1.8 mL of hydrofluoric acid.

[0019] Preferably, step S3 specifically involves:

[0020] Step S31: Place the sealed sample dissolving container into a constant temperature electric heating drying oven for the first heat preservation.

[0021] Step S32: After cooling, open the stainless steel outer casing, take out the polytetrafluoroethylene inner container, place it on a hot plate to evaporate to dryness until the solution volume is ≤0.5mL;

[0022] Step S33: Add nitric acid in sequence, evaporate to dryness, add nitric acid, evaporate to dryness, add aqua regia, cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0023] Step S34: After placing the sealed sample dissolving device into a constant temperature electric heating drying oven for a second heat preservation, wait for the sealed sample dissolving device to cool down.

[0024] Preferably, in step S3, if the lithium ore is of low-grade metamorphic rock type, the temperature of the first and second heat preservation is 180-200℃ and the heat preservation time is 24h; if the lithium ore is of high-grade metamorphic rock type, the temperature of the first and second heat preservation is 180-200℃ and the heat preservation time is >36h.

[0025] In step S32, the temperature of the heating plate is 200°C.

[0026] Preferably, in step S33, 0.8-1.2 mL of nitric acid is added twice, and 5-6 mL of aqua regia is added.

[0027] The volume ratio of 37% hydrochloric acid to 68% nitric acid in the aqua regia is 1:1.

[0028] Preferably, in step S4, the volume of the plastic volumetric flask is 50 mL;

[0029] During the determination process, all test solutions were added online with a rhodium internal standard solution at a concentration of 5-15 ng / mL.

[0030] When determining elements (Li, Na, K), a rhodium internal standard solution with a concentration of 5 ng / mL is added online; when determining elements (Cs, Rb, Be), a rhodium internal standard solution with a concentration of 15 ng / mL is added online, and a rhenium standard solution with a concentration of 2 ng / mL is added online as an auxiliary internal standard. This dual correction corrects for instrument drift and matrix effects, improving the accuracy of the determination.

[0031] The present invention employs the above-mentioned method for determining the amounts of various elements in lithium ore using a closed acid-soluble system, and its beneficial effects are as follows:

[0032] (1) The method of the present invention was used to determine the amount of each element in lithium ore, and the method was verified to have high accuracy and precision using national first-class standard materials: the relative standard deviation (RSD) was less than 13% (n=12) and the absolute value of the relative error was less than 12%.

[0033] (2) The present invention uses closed acid dissolution-inductively coupled plasma mass spectrometry to simultaneously determine the amounts of lithium (Li), rubidium (Rb), cesium (Cs), beryllium (Be), strontium (Sr), niobium (Nb), tantalum (Ta), zirconium (Zr), hafnium (Hf) and rare earth elements in lithium ore without the need for separate method operations, thereby improving the determination efficiency.

[0034] (3) The determination method in this invention has the characteristics of low chemical reagent consumption and low cost due to the use of closed sample dissolution, and is suitable for analyzing large batches and complex matrix lithium ore and rare metal samples.

[0035] (4) The determination method in this invention clearly states that the extended digestion condition for high-grade metamorphic lithium ore is to increase the dissolution time by more than 36 hours. Therefore, this invention covers different types of lithium ore samples and has strong practicality.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] Figure 1 This is a comparison of the results of different digestion times in an experimental example of the method for determining the amount of each element in lithium ore using a closed acid-dissolution system according to the present invention.

[0038] Figure 2 This is a comparative diagram of different extractants in an experimental example of the method for determining the amount of various elements in lithium ore using a closed acid-soluble system according to the present invention. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0041] The inductively coupled plasma mass spectrometer used in this invention is model iCAP Q (Thermoelectric Corporation, USA); the electronic balance is model CPA225D (Sartorius Scientific Instruments Co., Ltd.); the electric heating drying oven is model BGZ-240 (Shanghai Boxun Medical Biological Instruments Co., Ltd.); and the electric heating plate is model CTI462-30 (Tianjin Tuozhiming Experimental Instrument Technology Development Co., Ltd.).

[0042] The hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid used in this invention are all of superior purity (Chengdu Kelong Chemical Reagent Factory); the lithium ore is a national standard material using GBW07733, GBW07735, GBW07153, GBW07152, and GBW07184; among them, GBW07733 and GBW07735 were developed by the National Geological Experiment and Testing Center, and GBW07153, GBW07152, and GBW07184 were developed by the Shenyang Comprehensive Rock and Mineral Testing Center.

[0043] Example 1

[0044] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0045] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h using the national standard materials GBW07152 and GBW07733. Then, raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0046] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0047] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0048] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 24h.

[0049] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0050] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0051] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 24 hours. Allow the sealed sample container to cool down.

[0052] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0053] Example 2

[0054] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0055] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h using the national standard materials GBW07152 and GBW07733. Then, raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0056] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0057] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0058] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 200℃ and the heat preservation time is 24h.

[0059] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0060] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0061] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 200℃ for 24 hours. Allow the sealed sample container to cool down.

[0062] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0063] Comparative Example 1

[0064] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0065] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0066] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid, 1mL of purified nitric acid, and 1mL of sulfuric acid (HNO3-HF-H2SO4) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and then seal it with a stainless steel outer casing.

[0067] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0068] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 24h.

[0069] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0070] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0071] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 24 hours. Allow the sealed sample container to cool down.

[0072] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0073] Comparative Example 2

[0074] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0075] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0076] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid, 1mL of purified nitric acid, and 1mL of hydrochloric acid (HNO3-HF-HCl) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and then put it into a stainless steel outer casing for sealing.

[0077] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0078] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 24h.

[0079] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0080] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0081] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 24 hours. Allow the sealed sample container to cool down.

[0082] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0083] Comparative Example 3

[0084] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0085] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0086] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0087] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0088] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 200℃ and the heat preservation time is 24h.

[0089] Step S32: After cooling, open the stainless steel outer casing, take out the polytetrafluoroethylene inner can, and place it on a hot plate at a temperature of 140℃ to dry it.

[0090] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0091] Step S34: Place the sealed sample dissolving container into a constant temperature electric heating drying oven for a second heat preservation at 140℃ for 24 hours. Allow the sealed sample dissolving container to cool down.

[0092] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0093] Comparative Example 4

[0094] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0095] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h using the national standard materials GBW07152 and GBW07733. Then, raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0096] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0097] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0098] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 160℃ and the heat preservation time is 24h.

[0099] Step S32: After cooling, open the stainless steel outer casing, take out the polytetrafluoroethylene inner can, and place it on a hot plate at a temperature of 140℃ to dry it.

[0100] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0101] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 160℃ for 24 hours. Allow the sealed sample container to cool down.

[0102] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0103] Comparative Example 5

[0104] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0105] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0106] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0107] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0108] Step S31: Place the sealed sample dissolving container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 12h.

[0109] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0110] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0111] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 12 hours. Allow the sealed sample container to cool down.

[0112] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0113] Example 6

[0114] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0115] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h using the national standard materials GBW07152 and GBW07733. Then, raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0116] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0117] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0118] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 36h.

[0119] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0120] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0121] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 36 hours. Allow the sealed sample container to cool down.

[0122] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0123] Example 7

[0124] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0125] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0126] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0127] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0128] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 48h.

[0129] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0130] Step S33: Add 1 mL of nitric acid, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of aqua regia (1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0131] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 48 hours. Allow the sealed sample container to cool down.

[0132] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0133] Comparative Example 8

[0134] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0135] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0136] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0137] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0138] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 24h.

[0139] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0140] Step S33: Add 1 mL of nitric acid in sequence, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of hydrochloric acid (the volume ratio of hydrogen chloride to solvent is 1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0141] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 24 hours. Allow the sealed sample container to cool down.

[0142] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0143] Comparative Example 9

[0144] A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system includes the following steps:

[0145] Step S1: First, dry the lithium ore at a constant temperature of 90℃ for 1.5h, then raise the temperature to 110℃ and dry at a constant temperature for 1h. After cooling, place it in a desiccator for later use.

[0146] Step S2: Weigh 0.05g of pretreated lithium ore national standard materials GBW07152 and GBW07733 into a polytetrafluoroethylene inner container, add 2mL of hydrofluoric acid and 1mL of purified nitric acid (HNO3-HF) in sequence, let stand for 7min, cover the polytetrafluoroethylene inner container with the lid, and put it into a stainless steel outer casing for sealing.

[0147] Step S3: Incubate the sealed sample container twice to obtain the test solution;

[0148] Step S31: Place the sealed sample container into a constant temperature electric heating drying oven for the first heat preservation. The temperature of the first heat preservation is 180℃ and the heat preservation time is 24h.

[0149] Step S32: After cooling, open the stainless steel outer casing, remove the PTFE inner container, and place it on a hot plate at 200℃ to evaporate to dryness until the solution volume is ≤0.5mL.

[0150] Step S33: Add 1 mL of nitric acid in sequence, evaporate to dryness, add 1 mL of nitric acid, evaporate to dryness, add 5 mL of nitric acid (the volume ratio of concentrated nitric acid to solvent is 1:1), cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing.

[0151] Step S34: Place the sealed sample container into a constant temperature electric heating drying oven for a second heat preservation at 180℃ for 24 hours. Allow the sealed sample container to cool down.

[0152] Step S4: Transfer the test solution to a 50 mL plastic volumetric flask, dilute to the mark, and mix well. Analyze the solution using an inductively coupled plasma mass spectrometer (ICP-MS) to obtain the working curve. During the analysis, a 10 ng / mL rhodium internal standard solution was added online to all test solutions. The content of the analyte in the sample solution was calculated using the working curve.

[0153] Experimental Example

[0154] (I) The results of the determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium and rare earth elements in lithium ore in Example 1, Comparative Example 1 and Comparative Example 2 are compared, as shown in Table 1.

[0155] Table 1 Measurement Results

[0156]

[0157]

[0158] Note: Units marked with * are percentages.

[0159] As shown above, all three digestion systems meet the requirements of DZ / T 0130.3-2006 "Quality Management Standard for Geological and Mineral Laboratory Testing Part 3: Chemical Composition Analysis of Rock and Mineral Samples". However, in the NO3-HF-H2SO4 digestion system of Comparative Example 1, the relative deviations for lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, and hafnium were the smallest, but the rare earth element content was lower than the reference value. Due to the high boiling point of sulfuric acid, although the addition of sulfuric acid can increase the digestion temperature and provide ideal results for rare earth determination, sulfuric acid is difficult to volatilize. The temperature of sulfuric acid needs to reach 338℃ to effectively decompose the insoluble rare earth fluorides. Due to the temperature tolerance of the polytetrafluoroethylene (PTFE) sample dissolving vessel, the acid removal temperature cannot be increased, which will lead to hydrofluoric acid residue. This hydrofluoric acid reacts with rare earth elements to form insoluble fluoride precipitates, resulting in the rare earth element content being lower than the reference value.

[0160] The results obtained from the HNO3-HF-HCl digestion system in Comparative Example 2 and the HNO3-HF digestion system in Example 1 were not significantly different, although the addition of hydrochloric acid had a relatively small impact on the results. However, the method in Example 1 is more economical and simpler than the method in Comparative Example 2.

[0161] (II) The results of the determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium and rare earth elements in lithium ore were compared in Examples 1, 2, 3 and 4, as shown in Table 2.

[0162] Table 2 Measurement Results

[0163]

[0164] Note: Units marked with * are percentages.

[0165] As can be seen from the above, when the digestion temperature in Comparative Examples 3 and 4 is below 180℃, the test results of most elements in the standard material fluctuate greatly and the results are low, especially for tantalum and rare earth elements, which is due to incomplete sample digestion.

[0166] In Examples 1 and 2, when the digestion temperature was ≥180℃, the results of the standard substance determination were basically close to the accepted value, and the precision was good.

[0167] (III) The results of the determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium, and rare earth elements in lithium ore were compared with those of Example 1, Comparative Example 5, Comparative Example 6, and Comparative Example 7. Figure 1 As shown.

[0168] As the digestion time increases, the measured values ​​of the elements to be tested first increase and then remain stable. When the time is 24 hours as in Example 1, the measured values ​​are close to the theoretical values, and the relative error does not change much, which meets the requirements of DZ / T 0130.3-2006 "Quality Management Specifications for Geological and Mineral Laboratory Testing Part 3: Chemical Composition Analysis of Rock and Mineral Samples".

[0169] However, for high-grade metamorphic lithium ores, the dissolution time needs to be increased to more than 36 hours to ensure satisfactory analytical results for zirconium and hafnium.

[0170] (iv) The results of the determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium and rare earth elements in lithium ore were compared between Example 1, Comparative Example 8 and Comparative Example 9.

[0171] like Figure 2 As shown, in Comparative Example 8, when hydrochloric acid was used as the extractant, the contents of rubidium, cesium, tantalum, and rare earth elements were relatively low. In Comparative Example 9, when nitric acid was used as the extractant, the contents of lithium, rubidium, and cesium were relatively low.

[0172] In Example 1, when 50% aqua regia was used for extraction, the sample measurements were close to the values ​​identified by the standard substance, indicating good measurement stability. Because aqua regia has the coordinating effect of hydrochloric acid and the strong oxidizing property of nitric acid, poorly soluble and easily hydrolyzed elements are more easily extracted under the action of aqua regia.

[0173] (v) The national first-level standard materials GBW07152, GBW07184 and GBW07735 were measured by the determination method in Example 1. Each sample was analyzed in parallel 12 times, and the average value of the 12 tests was calculated. The precision of the method was examined by relative standard deviation (RSD) and the accuracy of the method was examined by relative error. The results are shown in Table 3.

[0174] Table 3 Precision and Accuracy Experiments

[0175]

[0176]

[0177] As shown in the table above, the precision of the three standard substances measured using the method in Example 1 is all less than 13% RSD and less than 12% absolute relative error. The actual measurement precision meets the requirements of DZT 0130-2006 "Quality Management Standard for Geological and Mineral Laboratory Testing".

[0178] Therefore, the present invention employs the above-mentioned method for determining the amount of various elements in lithium ore using a closed acid-soluble system. This method is characterized by its simple operation, high efficiency, and good stability, and enables the simultaneous determination of the amounts of lithium, rubidium, cesium, beryllium, strontium, niobium, tantalum, zirconium, hafnium, and rare earth elements in a large batch of lithium ore, thereby providing a reference for the determination of major and trace elements in lithium ore.

[0179] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for determining the amounts of various elements in lithium ore using a closed acid-soluble system, characterized in that, Includes the following steps: Step S1: Pre-treat the lithium ore; First, dry the lithium ore at a constant temperature of 85-95℃ for 1.5-2 hours, then raise the temperature to 110-115℃ and dry it at a constant temperature for 0.5-1 hour. After cooling, place it in a desiccator for later use. Step S2: Weigh the pretreated lithium ore into a sealed sample dissolving container, and add hydrofluoric acid and purified nitric acid in sequence, and then seal the sample dissolving container. Step S3: Incubate the sealed sample container twice to obtain the test solution; Step S4: Transfer the test solution to a plastic volumetric flask, bring the volume to the mark, shake well, and then use an inductively coupled plasma mass spectrometer to obtain the working curve. Use the working curve to calculate the content of the analyte in the sample solution.

2. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 1, characterized in that: The sealed sample dissolution apparatus includes a stainless steel outer shell and a polytetrafluoroethylene inner vessel; wherein, the stainless steel outer shell has a pressure resistance ≥10MPa and the polytetrafluoroethylene inner vessel has a temperature resistance ≥300℃. Step S2 specifically involves weighing the pretreated lithium ore into a polytetrafluoroethylene inner container, adding hydrofluoric acid and purified nitric acid in sequence, letting it stand for 5-8 minutes, covering the polytetrafluoroethylene inner container with its lid, and then sealing it with a stainless steel outer casing.

3. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 2, characterized in that: In step S2, 0.04-0.12 g of pretreated lithium ore is weighed; 1.5-2 mL of hydrofluoric acid is added, wherein the mass fraction of hydrofluoric acid is 40%; and 0.8-1 mL of purified nitric acid is added, wherein the purity of the purified nitric acid is ≥99.999%.

4. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 3, characterized in that: In step S2, when the Li2O content in the lithium ore is >5%, weigh 0.04-0.08g of the pretreated lithium ore; when the Li2O content in the lithium ore is ≤5%, weigh 0.08-0.12g of the pretreated lithium ore. When the silicon content in the lithium ore is >20%, add 1.8-2 mL of hydrofluoric acid; when the silicon content in the lithium ore is ≤20%, add 1.5-1.8 mL of hydrofluoric acid.

5. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 2, characterized in that: Step S3 specifically involves: Step S31: Place the sealed sample dissolving container into a constant temperature electric heating drying oven for the first heat preservation. Step S32: After cooling, open the stainless steel outer casing, take out the polytetrafluoroethylene inner container, place it on a hot plate to evaporate to dryness until the solution volume is ≤0.5mL; Step S33: Add nitric acid in sequence, evaporate to dryness, add nitric acid, evaporate to dryness, add aqua regia, cover the polytetrafluoroethylene inner can with the lid, and put the polytetrafluoroethylene inner can back into the stainless steel outer can for sealing. Step S34: After placing the sealed sample dissolving device into a constant temperature electric heating drying oven for a second heat preservation, wait for the sealed sample dissolving device to cool down.

6. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 5, characterized in that: In step S3, if the lithium ore is of low-grade metamorphic rock type, the temperature of the first and second heat preservation is 180-200℃ and the heat preservation time is 24h; if the lithium ore is of high-grade metamorphic rock type, the temperature of the first and second heat preservation is 180-200℃ and the heat preservation time is >36h. In step S32, the temperature of the heating plate is 200°C.

7. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 5, characterized in that: In step S33, 0.8-1.2 mL of nitric acid is added twice, and 5-6 mL of aqua regia is added. The volume ratio of 37% hydrochloric acid to 68% nitric acid in the aqua regia is 1:

1.

8. The method for determining the amounts of various elements in lithium ore using a closed acid-soluble system according to claim 1, characterized in that: In step S4, the volume of the plastic volumetric flask is 50 mL; During the determination process, all test solutions were added online with a rhodium internal standard solution at a concentration of 5-15 ng / mL.

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