Digestion method and detection method for coal gangue in coal gangue ICP-MS detection

Abstract

The invention relates to a digestion method and a detection method for coal gangue in coal gangue ICP-MS (inductively coupled plasma-mass spectrometry) detection, and aims to solve the problem that the accuracy of a detection result is relatively poor when lithium and gallium in the coal gangue are detected by ICP-MS. The digestion method comprises the following steps: mixing a coal gangue sample with a digestion solution, then carrying out first heating until brown gas disappears, and carrying out second heating until the brown gas disappears; then heating for the second time until the solution is clear and transparent, and adding dilute nitric acid to obtain a digested sample solution; according to the digestion method provided by the invention, the digestion process is specifically designed, the coal gangue can be digested without low-temperature ashing of the coal gangue, the volatilization loss of lithium and gallium in the low-temperature ashing process is avoided, and the content accuracy of trace lithium and gallium elements in the obtained coal gangue is high; and the method can also be used for analysis detection, content control and evaluation of other similar trace elements in the coal gangue.

Description

Technical Field

[0001] The invention relates to the field of coal gangue element analysis, and in particular to a coal gangue digestion method and a coal gangue detection method in coal gangue ICP-MS detection. Background Art

[0002] Coal gangue is a solid waste generated during coal mining and beneficiation, which contains trace elements of industrial grade, such as lithium, gallium and rare earth. In addition, coal gangue also contains a variety of trace harmful elements such as lead and arsenic. Therefore, accurate determination of trace elements is of great significance for the secondary utilization of coal gangue. However, the main minerals in coal gangue are difficult to decompose using common methods to detect trace elements, so it is quite difficult to detect the elements.

[0003] Although the prior art CN104849341A discloses a method for measuring the mercury content in coal gangue or fly ash, the method includes the following steps S1: digestion of the test sample; S2: electrochemical detection; S3: calculation of the mercury content. The method achieves good measurement results through unique process step operation and process parameter selection, has high accuracy and sensitivity, and provides a new measurement method for determining the content of such substances, which has good application value and prospects in industry and scientific research.

[0004] For example, CN111505106A discloses a method for determining the content of radioactive elements thorium and uranium in coal gangue, comprising the following steps: placing the coal gangue in a concentrated nitric acid-concentrated hydrofluoric acid-concentrated hydrogen peroxide system for closed microwave digestion, adding concentrated perchloric acid after digestion to heat on an acid remover to remove fluorine and silicon, heating the sample digestion solution until white smoke is emitted, adding nitric acid to dissolve salts after cooling, and dissolving with ultrapure water to obtain a test solution; preparing a series of standard solutions and internal standard solutions, and performing determination using an inductively coupled plasma mass spectrometer. In this scheme, hydrogen peroxide is added during microwave digestion, which significantly promotes the decomposition of fixed carbon in the sample and improves the dissolution effect of the elements to be measured, and the content of natural radioactive elements thorium and uranium in the coal gangue sample can be quickly determined.

[0005] Currently, the detection of trace elements and trace elements in coal gangue is usually carried out using ICP-AES (inductively coupled plasma atomic emission spectrometry) or ICP-MS (inductively coupled plasma mass spectrometry). However, when using ICP-AES and ICP-MS for digestion, there is still a problem of insufficient digestion of target elements such as lithium and gallium or the components of the digestion solution affecting the detection of lithium and gallium, resulting in inaccurate detection results. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a coal gangue digestion method and a detection method in coal gangue ICP-MS detection, so as to solve the problem of poor detection result accuracy when lithium and gallium in coal gangue are currently detected by ICP-MS.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for digesting coal gangue in coal gangue ICP-MS detection, the digestion method comprising:

[0009] The gangue sample is mixed with the digestion solution, and then heated for the first time until the brown gas disappears, and then the temperature is increased for the second heating until the solution is clear and transparent, and dilute nitric acid is added to obtain a digestion sample solution.

[0010] The digestion method provided by the present invention can digest coal gangue without low-temperature ashing of the coal gangue by specifically designing the digestion process, thereby avoiding the volatilization loss of lithium and gallium during the low-temperature ashing process, and the trace lithium and gallium content in the obtained coal gangue has high accuracy, and can also be used for analysis, detection, content control and evaluation of other similar trace elements in coal gangue.

[0011] As a preferred technical solution of the present invention, the coal gangue sample is a 200-mesh powder.

[0012] Preferably, the gangue sample is dried before being mixed with the digestion solution.

[0013] Preferably, the drying temperature is 80-100°C.

[0014] Preferably, the drying time is ≥12h.

[0015] As a preferred technical solution of the present invention, the solid-liquid ratio of the gangue sample to the digestion solution in the mixture is 1:(10-40) g / mL.

[0016] Preferably, the digestion solution comprises nitric acid, hydrofluoric acid and perchloric acid in a volume ratio of (3-6):(1-3):(1-3).

[0017] Preferably, the mass concentration of the nitric acid is 65-68%.

[0018] Preferably, the mass concentration of the hydrofluoric acid is ≥40%.

[0019] Preferably, the mass concentration of the perchloric acid is 70-72%.

[0020] As a preferred technical solution of the present invention, the first heating temperature is 170-230°C.

[0021] Preferably, the first heating time is 30-50 hours.

[0022] Preferably, during the first heating, 10-40 mL of digestion solution is added dropwise every 2-4 hours for each gram of coal gangue sample.

[0023] As a preferred technical solution of the present invention, the second heating temperature is 240-280°C.

[0024] Preferably, the second heating time is 12-15 hours.

[0025] Preferably, during the second heating, 5-20 mL of digestion solution is added dropwise every 1-3 h for each gram of coal gangue sample.

[0026] As a preferred technical solution of the present invention, the mass concentration of the dilute nitric acid is 10-12%.

[0027] Preferably, the liquid-to-solid ratio of the added amount of the dilute nitric acid to the coal gangue is (15-20) mL / g:1.

[0028] As a preferred technical solution of the present invention, the digestion method comprises:

[0029] The gangue sample is mixed with the digestion solution, and then heated for the first time until the brown gas disappears, and then heated for the second time until the solution is clear and transparent, and diluted nitric acid is added to obtain a digestion sample solution;

[0030] The gangue sample is a 200 mesh powder; the gangue sample is dried before being mixed with the digestion solution; the drying temperature is 80-100° C.; the drying time is ≥12 h; the solid-liquid ratio of the gangue sample to the digestion solution in the mixture is 1:(10-40) g / mL; the digestion solution comprises nitric acid, hydrofluoric acid and perchloric acid in a volume ratio of (3-6):(1-3):(1-3); the mass concentration of the nitric acid is 65-68%; the mass concentration of the hydrofluoric acid is ≥40%; the mass concentration of the perchloric acid is 70-72%; The temperature of the first heating is 170-230°C; the time of the first heating is 30-50h; in the first heating, 10-40mL of digestion solution is added every 2-4h for each gram of coal gangue sample; the temperature of the second heating is 240-280°C; the time of the second heating is 12-15h; in the second heating, 5-20mL of digestion solution is added every 1-3h for each gram of coal gangue sample; the mass concentration of the dilute nitric acid is 10-12%; the liquid-to-solid ratio of the added amount of the dilute nitric acid to the coal gangue (mL / g) is (15-20):1.

[0031] In a second aspect, the present invention provides a method for detecting lithium and gallium in coal gangue, the detection method comprising: using a digestion sample solution obtained by the digestion method according to any one of claims 1 to 7 as a sample solution in ICP-MS detection for detection.

[0032] As a preferred technical solution of the present invention, the detection method includes: drawing a standard working curve, sample detection and interference correction.

[0033] As a preferred technical solution of the present invention, the correlation coefficient between the element content and the corresponding spectral line intensity in the working curve obtained in the drawing of the standard working curve is ≥0.9999;

[0034] Preferably, the interference correction is to select heterogeneous isotopes of the interfering element for quantitative determination, calculate the interference coefficient according to the abundance ratio of the isotopes of the interfering element, and use a mathematical formula for correction.

[0035] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0036] The digestion process provided by the present invention realizes efficient digestion of coal gangue by adopting a specific digestion solution and combining a specific digestion process. When the digested solution is subjected to ICP-MS detection, efficient and accurate detection of lithium and gallium can be realized, and the detection accuracy for lithium and gallium is good. The relative standard deviation of lithium element detection in coal gangue is ≤0.33%, and the relative standard deviation of gallium element detection is ≤0.29%. DETAILED DESCRIPTION

[0037] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0038] This embodiment provides a method for digesting coal gangue in coal gangue ICP-MS detection, which is used to achieve efficient dissolution of trace elements and trace elements such as lithium and gallium related components in coal gangue, as follows:

[0039] The gangue sample is mixed with the digestion solution, and then heated for the first time until the brown gas disappears, and then the temperature is increased for the second heating until the solution is clear and transparent, and dilute nitric acid is added to obtain a digestion sample solution.

[0040] Specifically, the coal gangue sample is a 200-mesh powder.

[0041] Specifically, the gangue sample is dried before being mixed with the digestion solution.

[0042] Specifically, the drying temperature is 80-100°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0043] Specifically, the drying time is ≥12h, for example, it can be 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 16h, 16.5h, 17h or 18h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] Specifically, the solid-liquid ratio of the gangue sample to the digestion solution in the mixture is g / mL 1:(10-40), for example, it can be 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30, 1:32, 1:34, 1:36, 1:38 or 1:40, etc., but is not limited to the listed values, and other unlisted values ​​within the range are equally applicable.

[0045] Specifically, the digestion solution includes nitric acid, hydrofluoric acid and perchloric acid in a volume ratio of (3-6):(1-3):(1-3), for example, it can be 3:1:1, 3:2:1, 3:3:1, 3:1:2, 3:1:3, 4:1:1, 4:1:2, 4:1:3, 4:2:1, 3:3:1, 5:1:1, 5:2:1, 5:3:1, 5:1:2, 5:1:3, 6:1:1, 6:2:1, 6:3:2, 6:1:2, 6:1:3, 3:2:2, 1:1:1 or 2:1:1, but is not limited to the listed values, and other unlisted values ​​within the range are equally applicable.

[0046] Specifically, the mass concentration of the nitric acid is 65-68%, for example, it can be 65%, 65.2%, 65.4%, 65.6%, 65.8%, 66%, 66.2%, 66.4%, 66.6%, 66.8%, 67%, 67.2%, 67.4%, 67.6%, 67.8% or 68%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] Specifically, the mass concentration of the hydrofluoric acid is ≥40%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] Specifically, the mass concentration of the perchloric acid is 70-72%, for example, it can be 70%, 70.1%, 70.2%, 70.3%, 70.4%, 70.5%, 70.6%, 70.7%, 70.8%, 70.9%, 71%, 71.1%, 71.2%, 71.3%, 71.4%, 71.5%, 71.6%, 71.7%, 71.8%, 71.9% or 72%, etc., but is not limited to the listed values, and other values ​​not listed within the range are equally applicable.

[0049] Specifically, the first heating temperature is 170-230°C, for example, it can be 170°C, 172°C, 174°C, 176°C, 178°C, 180°C, 182°C, 184°C, 186°C, 188°C, 190°C, 192°C, 194°C, 196°C, 198°C, 200°C, 202°C, 204°C, 206°C, 208°C, 210°C, 212°C, 214°C, 216°C, 218°C, 220°C, 222°C, 224°C, 226°C, 228°C or 230°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range are equally applicable.

[0050] Specifically, the first heating time is 30-50h, for example, it can be 30h, 31h, 32h, 33h, 34h, 35h, 36h, 37h, 38h, 39h, 40h, 41h, 42h, 43h, 44h, 45h, 46h, 47h, 48h, 49h or 50h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0051] Specifically, in the first heating, 10-40 mL of digestion solution is added dropwise every 2-4 h for each gram of coal gangue sample. For example, the interval time can be 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h or 4 h, etc., and 10-40 mL of digestion solution is added dropwise for each gram of coal gangue sample, such as 10 mL, 12 mL, 14 mL, 16 mL, 18 mL, 20 mL, 22 mL, 24 mL, 26 mL, 28 mL, 30 mL, 32 mL, 34 mL, 36 mL, 38 mL or 40 mL, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0052] Specifically, the second heating temperature is 240-280°C, for example, it can be 240°C, 242°C, 244°C, 246°C, 248°C, 250°C, 252°C, 254°C, 256°C, 258°C, 260°C, 262°C, 264°C, 266°C, 268°C, 270°C, 272°C, 274°C, 276°C, 278°C or 280°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0053] Specifically, the second heating time is 12-15h, for example, it can be 12h, 12.2h, 12.4h, 12.6h, 12.8h, 13h, 13.2h, 13.4h, 13.6h, 13.8h, 14h, 14.2h, 14.4h, 14.6h, 14.8h or 15h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] Specifically, in the second heating, 5-20 mL of digestion solution is added dropwise at intervals of 1-3 h per gram of gangue sample. For example, the interval time can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h, etc., and 5-20 mL of digestion solution is added dropwise for each gram of gangue sample, such as 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, 10 mL, 11 mL, 12 mL, 13 mL, 14 mL, 15 mL, 16 mL, 17 mL, 18 mL, 19 mL or 20 mL, etc., but are not limited to the listed values, and other values ​​not listed within the range are equally applicable.

[0055] Specifically, the mass concentration of the dilute nitric acid is 10-12%, for example, it can be 10%, 10.1%, 10.2%, 10.3%, 10.4%, 10.5%, 10.6%, 10.7%, 10.8%, 10.9%, 11%, 11.1%, 11.2%, 11.3%, 11.4%, 11.5%, 11.6%, 11.7%, 11.8%, 11.9% or 12%, etc., but is not limited to the listed values, and other values ​​not listed in the range are also applicable.

[0056] Specifically, the liquid-to-solid ratio of the added amount of dilute nitric acid to coal gangue mL / g is (15-20):1, for example, it can be 15:1, 15.5:1, 16:1, 16.5:1, 17:1, 17.5:1, 18:1, 18.5:1, 19:1, 19.5:1 or 20:1, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0057] Furthermore, the obtained digestion solution is used to detect lithium and gallium in the liquid phase by ICP-MS, which specifically includes: drawing a standard working curve, sample detection and interference correction.

[0058] Specifically, the correlation coefficient between the element content and the corresponding spectral line intensity in the working curve obtained in the drawing of the standard working curve is ≥0.9999.

[0059] Specifically, the interference correction is to select heterogeneous isotopes of interfering elements for quantitative determination, calculate the interference coefficient according to the abundance ratio of the isotopes of the interfering elements, and use a mathematical formula for correction.

[0060] The actual detection example for coal gangue is as follows:

[0061] Example 1

[0062] This embodiment provides a coal gangue sample digestion method and a specific ICP-MS detection process, which are as follows:

[0063] Ⅰ. Sample preparation: The gangue sample was crushed and dried in a forced air drying oven at 80°C for 12 hours, and then divided into five samples (referred to as sample 1, sample 2, sample 3, sample 4, and sample 5) after reduction. Each sample was digested and tested.

[0064] II. Sample digestion: Use an analytical balance to weigh 0.2 g of the dried sample and transfer it into a polytetrafluoroethylene crucible; prepare the digestion solution by taking 24 mL of 65% HNO 3 , 6 mL of 40% HF, 6 mL of 70% HClO 4 , mix well in a polytetrafluoroethylene beaker to obtain a digestion solution;

[0065] Add 2 mL of digestion solution to the sample and shake well. Cover and heat on a hot plate at 170°C for 40 h, adding 2 mL of digestion solution every 4 h. After the brown gas disappears, raise the temperature to 240°C and continue heating for 12 h, adding 1 mL of digestion solution every 2 h until the solution is clear and transparent.

[0066] Open the lid, drive off the remaining acid solution, stop heating, add 3mL of 11% dilute nitric acid, wait for the sample solution to cool to room temperature, transfer to a 100mL volumetric flask and dilute to the scale with ultrapure water for later use.

[0067] III. Preparation of standard solution: Take 1mL of 1000ug / L lithium and gallium standard stock solutions into a 1L volumetric flask, dilute to the mark with ultrapure water to obtain a standard solution with a lithium and gallium concentration of 1ppm. Take 1000ug / L rhodium standard stock solution and dilute it to 5ppb with ultrapure water as the internal standard solution. Prepare standard solutions with concentrations of 1ppb, 2ppb, 4ppb, 5ppb, 10ppb, 20ppb, 50ppb, 100ppb and 200ppb (the 0ppb standard solution is ultrapure water).

[0068] IV. Drawing a standard working curve: A set of 10 standard solutions with different concentrations (0 ppb, 1 ppb, 2 ppb, 4 ppb, 5 ppb, 10 ppb, 20 ppb, 50 ppb, 100 ppb, and 200 ppb) were obtained. The mass contents of lithium and gallium in the ten sets of solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS). A working curve of the relationship between the content and the spectral line intensity was drawn with the mass content of the element as the abscissa and the intensity of the spectral line determined by the element as the ordinate. The correlation coefficient between the lithium and gallium contents in the curve and the corresponding spectral line intensity was 0.9999.

[0069] V. Sample detection: Inductively coupled plasma mass spectrometer (ICP-MS) is used to measure the spectral line intensity of the element to be measured in the solution after dilution in step II. The lithium and gallium contents of the diluted sample can be obtained from the horizontal and vertical coordinates corresponding to the working curve. After calculation, the lithium and gallium contents in the actual sample are shown in Table 1.

[0070] Table 1

[0071]

[0072] VI Interference Correction: Selecting the Detection Isotopes of Lithium and Gallium 6 Li and 69 Ga, using isotopes 103 Rh is used as an internal standard element to eliminate non-mass spectrometric interference. The heterogeneous isotopes of interfering elements are selected for quantitative determination, and the interference coefficient is calculated based on the abundance ratio of the isotopes of the interfering elements. The mathematical formula is used for correction, and the instrument automatically deducts the mass spectrometric interference.

[0073] Example 2

[0074] The only difference from Example 1 is that no additional digestion solution is added during the first heating process during the digestion process, but the added digestion solution is directly added to the sample when mixed to ensure that the total amount of digestion solution remains unchanged.

[0075] The actual lithium and gallium contents in the samples after calculation are shown in Table 2.

[0076] Table 2

[0077]

[0078] Example 3

[0079] The only difference from Example 1 is that no additional digestion solution is added during the second heating process during the digestion process, but the added digestion solution is directly added to the sample when mixed to ensure that the total amount of digestion solution remains unchanged.

[0080] The actual lithium and gallium contents in the samples after calculation are shown in Table 3.

[0081] Table 3

[0082]

[0083] During the detection process of the above embodiment, the operating parameters of the inductively coupled plasma mass spectrometer are controlled as follows: RF power 1550W; cooling gas flow rate: 15.00L / min; auxiliary gas flow rate: 0.8L / min; nebulizer flow rate: 0.95L / min; argon: 0.5L / min; peristaltic pump speed: 999.98Hz; injection flushing time: 15s; integration time: short wave 25s, long wave 5s.

[0084] It can be seen from the results of the above embodiments that the digestion method provided by the present invention can digest coal gangue without low-temperature ashing of coal gangue by specifically designing the digestion process, thereby avoiding the volatilization loss of lithium and gallium during the low-temperature ashing process, and the trace lithium and gallium content in the obtained coal gangue is highly accurate, and can also be used for analysis, detection, content control and evaluation of other similar trace elements in coal gangue.

[0085] It is stated that the present invention uses the above embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0086] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0088] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for digesting coal gangue in coal gangue ICP-MS detection, characterized in that: The digestion method comprises: The gangue sample is mixed with the digestion solution, and then heated for the first time until the brown gas disappears, and then the temperature is increased for the second heating until the solution is clear and transparent, and dilute nitric acid is added to obtain a digestion sample solution.

2. The digestion method according to claim 1, wherein: The coal gangue sample is a 200 mesh powder; Preferably, the gangue sample is dried before being mixed with the digestion solution; Preferably, the drying temperature is 80-100°C; Preferably, the drying time is ≥12h.

3. The digestion method as claimed in claim 1 or 2, characterized in that: The solid-liquid ratio of the gangue sample to the digestion solution in the mixture is 1:(10-40) g / mL; Preferably, the digestion solution comprises nitric acid, hydrofluoric acid and perchloric acid in a volume ratio of (3-6):(1-3):(1-3); Preferably, the mass concentration of the nitric acid is 65-68%; Preferably, the mass concentration of the hydrofluoric acid is ≥40%; Preferably, the mass concentration of the perchloric acid is 70-72%.

4. The digestion method according to any one of claims 1 to 3, characterized in that: The first heating temperature is 170-230°C; Preferably, the first heating time is 30-50h; Preferably, during the first heating, 10-40 mL of digestion solution is added dropwise every 2-4 hours for each gram of coal gangue sample.

5. The digestion method according to any one of claims 1 to 4, characterized in that: The second heating temperature is 240-280°C; Preferably, the second heating time is 12-15h; Preferably, during the second heating, 5-20 mL of digestion solution is added dropwise every 1-3 h for each gram of coal gangue sample.

6. A digestion method as described in any one of claims 1 to 5, characterized in that, The mass concentration of the dilute nitric acid is 10-12%; Preferably, the liquid-to-solid ratio of the added amount of the dilute nitric acid to the coal gangue is (15-20) mL / g:

1.

7. The digestion method according to any one of claims 1 to 6, characterized in that: The digestion method comprises: The gangue sample is mixed with the digestion solution, and then heated for the first time until the brown gas disappears, and then heated for the second time until the solution is clear and transparent, and diluted nitric acid is added to obtain a digestion sample solution; The gangue sample is a 200 mesh powder; the gangue sample is dried before being mixed with the digestion solution; the drying temperature is 80-100° C.; the drying time is ≥12 h; the solid-liquid ratio of the gangue sample to the digestion solution in the mixture is 1:(10-40) g / mL; the digestion solution comprises nitric acid, hydrofluoric acid and perchloric acid in a volume ratio of (3-6):(1-3):(1-3); the mass concentration of the nitric acid is 65-68%; the mass concentration of the hydrofluoric acid is ≥40%; the mass concentration of the perchloric acid is 70-72%; The temperature of the first heating is 170-230°C; the time of the first heating is 30-50h; in the first heating, 10-40mL of digestion solution is added every 2-4h for each gram of coal gangue sample; the temperature of the second heating is 240-280°C; the time of the second heating is 12-15h; in the second heating, 5-20mL of digestion solution is added every 1-3h for each gram of coal gangue sample; the mass concentration of the dilute nitric acid is 10-12%; the liquid-to-solid ratio of the added amount of the dilute nitric acid to the coal gangue (mL / g) is (15-20):

1.

8. A method for detecting lithium and gallium in coal gangue, characterized in that: The detection method comprises: using the digested sample solution obtained by the digestion method according to any one of claims 1 to 7 as the sample solution in ICP-MS detection for detection.

9. The detection method according to claim 8, characterized in that: The detection method includes: drawing a standard working curve, sample detection and interference correction.

10. The detection method according to claim 9, characterized in that: The correlation coefficient between the element content and the corresponding spectral line intensity in the working curve obtained in the drawing of the standard working curve is ≥ 0.9999; Preferably, the interference correction is to select heterogeneous isotopes of the interfering element for quantitative determination, calculate the interference coefficient according to the abundance ratio of the isotopes of the interfering element, and use a mathematical formula for correction.

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