A method for analyzing environmental geochemical characteristics based on trace elements in coal

Abstract

The present invention relates to the field of coal trace element technology and discloses a method for analyzing the environmental geochemical characteristics of coal trace elements. The method comprises the following steps: S1: collecting coal seam map information at the current location and constructing a three-dimensional map model of the current location using Tableau software; S2: extracting sample sampling points on the constructed three-dimensional map model and calibrating the sample sampling point information; S3: collecting samples at locations corresponding to the extracted sample sampling points and pre-processing the collected samples. The method determines the sedimentary environment characteristics of the coal based on the δCe / δEu, U / Th, V / (V+Ni), Sr / Ba, B, and Sr / Cu indicators. Ba reflects the deposition mode, the Sr / Ba ratio determines the deposition environment, the Sr / Cu ratio determines the temperature and climate, and the V / (V+Ni), U / Th, δCe, and δCe / δEu reflect the oxidation environment. The coal sample information after detection and analysis is then combined with the collection site information and input into the constructed three-dimensional model, facilitating subsequent query of the coal sample information progress and providing research data for subsequent researchers.

Description

Technical Field

[0001] The present invention relates to the technical field of coal trace elements, and in particular to an environmental geochemical characteristic analysis method based on coal trace elements. Background Art

[0002] Compared to other fossil fuels, coal represents the world's most abundant and widely used fossil fuel reserves, and it is also the easiest energy source to develop and utilize. Throughout my country's industrialization, the coal industry has underpinned its economic development, benefiting both the nation and its people. It serves as a crucial strategic safeguard for my country's energy security and economic development. The sustainable utilization of coal resources is crucial to the nation's ecological security. my country boasts a vast territory and abundant resources, with coal covering an area of ​​5.5 million square kilometers and total coal reserves of 5.06 million tons. According to data from the World Energy Council, as of 2009, China's recoverable coal reserves were approximately 1.0387 million tons, making it the world's third-largest producer, accounting for approximately 14% of the world's total reserves. Coal resources are the primary energy source for China's energy consumption system. According to the China Statistical Yearbook, my country's total coal production in 2021 reached 2.93141 million tons. Coal resources account for approximately 95% of fossil energy and 67% of total primary energy production. my country consumes over half of the world's coal resources, making coal a dominant force in the future Chinese economy, a trend not expected to change over the next 50 years. Coal is a primary energy source in many developed and developing countries, despite the potential environmental and human health consequences of its mining, processing, combustion, and the waste generated after combustion. Recently, scientists have become increasingly interested in understanding the causes of these issues in order to more effectively utilize coal resources.

[0003] Among the coal quality parameters, trace elements in coal have a great impact on the environment, economy, technology and human health. Coal is a complex heterogeneous mixture composed of organic and inorganic components of different abundances and sources [6]. Although inorganic components usually only account for a small part of the coal composition, most of the problems related to coal are related to this part. Inorganic components come from three different types of components, including dissolved salts in coal pore water, inorganic elements combined with organic compounds (especially trace elements), and mineral compounds. Inorganic matter in coal, like organic matter, is a product of peat accumulation and coal stratification. The organic and inorganic components in coal not only contain geological information on the characteristics of the sedimentary environment and the formation of coal-bearing sequences, but also contain useful environmental information on the control of trace element pollution during coal mining, cleaning, combustion and utilization. Therefore, the analysis and study of the mineralogy, geochemistry and occurrence of elements in coal is particularly important. Summary of the Invention

[0004] In order to solve the technical problem of inconvenient research on the mineralogy, geochemistry and occurrence mode of elements in coal, the present invention provides an environmental geochemical characteristic analysis method based on trace elements in coal.

[0005] The present invention is implemented by the following technical solution: a method for analyzing environmental geochemical characteristics of coal trace elements, comprising the following steps:

[0006] S1 collects coal seam map information at the current location and uses Tableau software to build a 3D map model of the current location;

[0007] S2 extracts sample sampling points on the constructed three-dimensional map model and calibrates the sample collection point information;

[0008] S3 collects samples at the corresponding positions of the sample sampling points and pre-processes the collected samples;

[0009] S4 tests and analyzes the pre-treated samples and collects sample test information;

[0010] S5 performs coal quality and coal rock characteristic analysis based on the sample test information obtained;

[0011] S6 performs geochemical characteristic analysis of coal elements based on the sample test information obtained;

[0012] S7 performs coal deposition characteristic analysis based on the sample test information obtained from the test;

[0013] S8 integrates the sample analysis content with the sample collection point information and injects it into the three-dimensional map model.

[0014] As a further improvement of the above solution, the sample collection point information in step S2 includes sample name, sample coordinates and sample depth information.

[0015] As a further improvement of the above solution, the sample test information in step S4 includes basic physical and chemical property information, trace element information, major element information, mineral information, organic component information and occurrence state information of the sample coal.

[0016] As a further improvement of the above solution, the coal quality and coal rock characteristics in step S5 include coal quality characteristics, coal rock characteristics and coal mineral characteristics.

[0017] As a further improvement of the above solution, the coal element geochemical characteristics in step S6 include major element content characteristics, trace element content characteristics, rare earth element distribution characteristics and trace element occurrence state.

[0018] As a further improvement of the above solution, the coal deposition characteristics in step S7 include paleo-salinity characteristics, paleo-climate characteristics and paleo-redox environment characteristics.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention determines the sedimentary environment characteristics of coal based on the δCe / δEu, U / Th, V / (V+Ni), Sr / Ba, B, and Sr / Cu indicators. Ba reflects the sedimentary mode, the Sr / Ba ratio determines the sedimentary environment, Sr / Cu determines the temperature and climate, and V / (V+Ni), U / Th, δCe, and δCe / δEu reflect the oxidizing environment.

[0021] 2. The present invention combines the coal sample information after detection and analysis with the collection site information and puts it into the constructed three-dimensional model, which facilitates subsequent progress query of the coal sample information and provides research data for subsequent researchers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The Tangjiahui coal mine map provided in Example 2 of the present invention;

[0023] Figure 2 A schematic diagram of the structure of the sampling coal seam provided by the present invention;

[0024] Figure 3 Schematic diagram of clay minerals and pyrite in coal determined by microscopic coal rock provided by the present invention;

[0025] Figure 4 This is the analysis result of the main minerals in coal using XRD and HighScorePlus software;

[0026] Figure 5 This is the result of ICP-MS testing of trace elements in the 6th coal and roof and floor plates of the Taiyuan Formation in Tangjiahui, Inner Mongolia.

[0027] Figure 6 It is a stacked bar chart showing the percentage of relative content of trace elements under different occurrence states;

[0028] Figure 7 This is the result of coal deposition environment characteristic analysis, where:

[0029] Figure 7 A is the result of Ba content analysis;

[0030] Figure 7 B is the Sr / Ba ratio analysis result diagram;

[0031] Figure 7 C is the Sr / Cu ratio analysis result diagram;

[0032] Figure 7 D is the V / (V+Ni) ratio analysis result diagram;

[0033] Figure 7 E is the U / Th ratio analysis result diagram. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0035] Example 1:

[0036] The present embodiment provides a method for analyzing environmental geochemical characteristics of coal trace elements, comprising the following steps:

[0037] S1 collects coal seam map information at the current location and uses Tableau software to build a 3D map model of the current location;

[0038] S2 extracts sample sampling points on the constructed three-dimensional map model and calibrates the sample collection point information, where the sample collection point information includes sample name, sample coordinates and sample depth information;

[0039] S3 collects samples at the corresponding positions of the sample sampling points and pre-processes the collected samples;

[0040] S4 tests and analyzes the pretreated sample to collect sample test information, wherein the sample test information includes basic physical and chemical property information, trace element information, major element information, mineral information, organic component information and occurrence state information of the sample coal;

[0041] S5 performs coal quality and coal rock characteristics analysis based on the sample test information obtained from the test, wherein the coal quality and coal rock characteristics include coal quality characteristics, coal rock characteristics and coal mineral characteristics;

[0042] S6 performs coal element geochemical characteristic analysis based on the sample test information obtained from the test, wherein the coal element geochemical characteristics include the content characteristics of major elements, the content characteristics of trace elements, the distribution characteristics of rare earth elements and the occurrence state of trace elements;

[0043] S7 analyzes coal deposition characteristics based on the sample test information obtained, wherein the coal deposition characteristics include paleo-salinity characteristics, paleo-climate characteristics, and paleo-redox environment characteristics;

[0044] S8 integrates the sample analysis content with the sample collection point information and injects it into the three-dimensional map model.

[0045] Example 2:

[0046] Coal seam map site selection

[0047] Taking Tangjiahui Coal Mine as an example, Tangjiahui Coal Mine is located in Inner Mongolia Autonomous Region, in the southwest of Zhungeer Coalfield in Ordos City. Figure 1 As shown, it is adjacent to the Heidaigou Coal Mine, specifically located about four kilometers northwest of Xuejiawan Town, Zhungeer Banner People's Government, with geographic coordinates: East longitude: 111°10′27″~111°14′34″, North latitude: 39°52′45″~39°57′22″. The Tangjiahui Coal Mine field is an irregular polygon with an area of ​​approximately 28.57km2. After importing the coal mine map information into Tableau software, Tableau software was used to construct a three-dimensional map model.

[0048] Example 3:

[0049] Sample collection

[0050] The coal seam sampled this time is the No. 6 coal seam of the Taiyuan Formation of Tangjiahui Coal Mine in Inner Mongolia. Figure 2 As shown, the Tangjiahui No. 6 coal seam is located in the upper third section of the Taiyuan Formation. The coal seam is remarkably thick, reaching 486 meters, and contains multiple layers of interbedded gangue, resulting in a complex structure. The thickness of this seam decreases gradually in the northern part of the Tangjiahui mining area compared to the central and southern parts, while the southern and central parts are well developed and thicker. The No. 6 coal seam is a stable, mineable coal seam in the Tangjiahui mining area, with mining occurring throughout the entire area.

[0051] According to "GB / T482-2008 Coal Sampling Methods," equidistant slot sampling was conducted in the 6th coal seam of the Taiyuan Formation in the Tangjiahui area of ​​Inner Mongolia. Each sampling point was spaced 1 meter apart. A total of 12 coal samples were collected, labeled TJH-1 to TJH-12 (abbreviated as T-1 to T-12) from top to bottom. One top and one bottom were labeled TJH-T and TJH-B, respectively, for a total of 14 samples. To prevent contamination from the external environment, the coal samples were placed in polyethylene plastic bags, which were then sealed with a cotton bag.

[0052] Example 4:

[0053] Sample pretreatment

[0054] After collection, the coal samples were spread flat on A4 paper and placed in a room free of laboratory chemicals. After air-drying, debris was removed from the coal. A 20g sample was collected from each group using the quartering method. The coal samples were broken into small pieces using a geological hammer. The small pieces were then placed in a mortar and pestle and ground into a powder. Finally, the powder was passed through a 200-mesh nylon sieve to obtain a 0.075mm diameter coal powder. The powder was then placed in a labeled and sealed plastic bag for future use. The sample was then stored in a brown reagent bottle with a label for industrial analysis, total sulfur determination, and determination of trace elements. Another portion of the coal sample was used to prepare optical thin sections and optical slices. To ensure the accuracy of subsequent experimental tests and analyses, the coal sample pretreatment process required minimizing experimental error. Before reuse, the experimental instruments, including the geological hammer, agate hammer, mortar, pestle, and nylon sieve, were wiped with a cotton cloth dipped in anhydrous ethanol. The instruments were allowed to air-dry, and the pretreatment process was repeated for the next sample. After sample pretreatment, experimental tests and analyses were performed.

[0055] Example 5:

[0056] Sample testing and analysis

[0057] A. Basic physical and chemical properties of coal

[0058] Ash content (Ad), volatile matter (Vdaf), moisture (Mad) and calorific value (Qgr,d) were determined using an industrial analyzer in accordance with the "GB / T211-2008 Industrial Analysis Method for Coal" standard; the total sulfur content was determined using a WS-S101 automatic sulfur analyzer with reference to the "GB / T214-2007 Coulometric Titration Method" standard.

[0059] B trace elements

[0060] Determination of trace elements in coal samples: Grind the broken coal samples into 0.075 mm powdered coal, weigh 0.1 g of the powdered coal sample and place it in a crucible, add 10 mL of HCl, cover and let it stand for 24 hours, then add 26 mL of aqua regia (HNO3:HF:HCLO4=5:5:3) to a polytetrafluoroethylene crucible, place them on a hot plate (fume hood) in order for heating and digestion, and set the temperature to 180-220°C. During the heating process on the hot plate, continuously add aqua regia to ensure that the liquid in the crucible is not evaporated, and digest until the liquid in the crucible becomes transparent. Open the lid and allow the acid in the solution to evaporate naturally. When the solution in the crucible becomes transparent crystals, remove the crucible and let it stand to cool, then dilute to a 50 mL colorimetric tube with 1% HClO4 solution, and finally filter and store in a 10 mL centrifuge tube for testing. The digested coal samples were analyzed using an inductively coupled plasma mass spectrometer (Agilent 7500cx ICP-MS, Agilent, USA) to determine the trace elements C in the coal.

[0061] C. Constant elements

[0062] An appropriate amount of raw coal sample was taken, and after the raw coal sample was completely ashed at 815℃, the ash sample was pressed into tablets, and the content of major element oxides was determined using a ZSXPrimusⅡ X-ray fluorescence spectrometer (XRF).

[0063] D. Mineral Analysis

[0064] The ground coal sample was taken and tableted using a tablet press. The tablets were measured using a SmartLab 9kW X-ray diffractometer (XRD, Rigaku, Japan).

[0065] E. Organic component analysis

[0066] Coal rock identification was carried out according to the national standard "Classification of Microscopic Components of Bituminous Coal" (GB / T15588-2013). A research-grade stereo microscope (M165FC, Leica, Germany) was used to observe the morphological characteristics of microscopic coal rock components. The microscopic components of coal rock sections were observed and photographed under reflected light, and then differentiated and quantitatively counted.

[0067] F. Occurrence state analysis

[0068] The occurrence state of trace elements in coal was analyzed and studied by Tessier five-step continuous extraction method:

[0069] (1) Exchangeable state

[0070] Weigh 0.5g of ground coal sample and place it in a 50mL centrifuge tube. Add 10mL of 1.0mol / L magnesium chloride solution and shake well. Oscillate the sample at 200 rpm at 25°C for 2 hours. Then, centrifuge the sample at 4500 rpm. After 15 minutes, remove the supernatant and add approximately 10mL of deionized water to the residue. Continue centrifuging at 4500 rpm. After 15 minutes, remove the supernatant, dilute it to 100mL, and filter it through a 0.45μm filter into a 100mL sealed plastic bottle for ICP-MS analysis.

[0071] (2) Carbonate-bound state

[0072] Add 10 mL of 1.0 mol / L sodium acetate solution to the residue from the previous step and shake well. Adjust the shaker to 200 oscillations / min at 25°C for 5 hours. Remove the shaker and centrifuge at 4500 rpm. After 15 minutes, remove the supernatant and add approximately 10 mL of deionized water to the residue. Continue centrifuging at 4500 rpm. After 15 minutes, pour off the supernatant and dilute to 100 mL. Filter through a 0.45 μm filter membrane into a 100 mL sealed plastic bottle for ICP-MS analysis.

[0073] (3) Iron and manganese oxidation state

[0074] Add 20 mL of the hydroxylamine hydrochloride-hydrochloric acid mixture to the residue from the previous step and shake well. Adjust the shaker to 200 oscillations / min at 25°C for 6 hours. Remove the shaker and centrifuge at 4500 rpm. After 15 minutes, remove the supernatant and add approximately 10 mL of deionized water to the residue. Continue centrifuging at 4500 rpm. After 15 minutes, pour off the supernatant and dilute to 100 mL. Filter through a 0.45 μm filter membrane into a 100 mL sealed plastic bottle for ICP-MS analysis.

[0075] (4) Organically bound state

[0076] Add 3.0mL of HNO3 (0.02mol / L) and 5.0mL of H2O2 to the residue from the previous step and shake well. Adjust the temperature of the thermostatic water bath to 85°C and keep it in the water bath for 1.5 hours, shaking the reagent bottle every ten minutes. After the water bath, add 3.0mL of H2O2 to the reagent bottle and continue to keep it in the water bath for one hour, shaking the reagent bottle every ten minutes. Remove the reagent bottle and place it at room temperature. After cooling, add 2.5mL of ammonium acetate-nitric acid solution, dilute the sample to 25mL with deionized water, shake well, place it at room temperature, and centrifuge it at 4500r / min after ten hours. After fifteen minutes, the supernatant was removed, 10 mL of deionized water was added to the residue in the reagent bottle, and the mixture was centrifuged at 4500 r / min. After fifteen minutes, the supernatant was removed and the volume was adjusted to 100 mL. The supernatant was filtered through a 0.45 μm filter membrane into a 100 mL sealed plastic bottle for ICP-MS determination.

[0077] (5) Residue state

[0078] The residue from the previous step was dried in an oven. Grind the dried residue and weigh 0.1 g for digestion using the same digestion method as for trace element determination. The volume was then adjusted to 100 mL for ICP-MS analysis.

[0079] Example 6:

[0080] Coal quality and coal rock characteristics

[0081] 1. Coal quality characteristics

[0082] According to GB / T15224-2010 Coal Quality Classification, MT / T850-2000 Coal Total Moisture Classification and MT / T849-2000 Coal Volatile Yield Classification, the moisture, volatile matter, ash, calorific value and total sulfur of Tangjiahui Taiyuan Formation 6 coal were analyzed. The moisture (Mad) content of the coal was between 6.85% and 10.52%, with an average moisture content of 7.87%, which is a low total moisture coal; the volatile matter (Vdaf) content was between 29.9% and 41.76%, with an average volatile matter content of 37. The ash content (Ad) ranges from 7.9% to 37.19%, with an average ash content of 20.98%, making it a medium-ash coal. The calorific value (Qgr,d) ranges from 20.88% to 32.93%, with an average calorific value of 27.43%, making it a high-calorific value coal. The average maximum reflectance (Rmax) of the vitrinite group ranges from 0.31 to 0.84, with an average of 0.54. The coal has a low degree of metamorphism and is a long flame coal, a type of bituminous coal with the lowest degree of metamorphism and weaker cohesion, as shown in Table 1.

[0083] Table 1 shows the coal quality analysis results of Tangjiahui 6 coal:

[0084]

[0085]

[0086] 2. Coal rock characteristics

[0087] According to the analysis of coal mine microscopic components, the vitrinite in Tangjiahui 6 coal is the main organic microscopic component, the inertinite content is lower than that of the vitrinite, and the exinite accounts for a small proportion, as shown in Table 2;

[0088] Table 2 shows the content of microscopic coal rock components in Tangjiahui Coal Mine:

[0089] sample Vitrinite Inertinite Exinite TJH-1 79.86％ 18.64％ 1.50％ TJH-2 51.77％ 36.14％ 12.08％ TJH-3 58.01％ 40.17％ 1.82％ TJH-4 30.24％ 64.91％ 4.85％ TJH-5 47.81％ 33.72％ 18.46％ TJH-6 34.31％ 62.55％ 3.14％ TJH-7 90.35％ 7.68％ 1.97％ TJH-8 55.62％ 30.47％ 13.91％ TJH-9 51.38％ 46.50％ 2.13％ TJH-10 62.41％ 37.59％ 0.00％ TJH-11 68.26％ 20.89％ 10.84％ TJH-12 82.23％ 14.91％ 2.86％ average value 59.35％ 34.51％ 6.13％ Minimum 30.24％ 7.68％ 0.00％ Maximum 90.35％ 64.91％ 18.46％

[0090] Characteristics of vitrinite in coal

[0091] In the 6th coal of Taiyuan Formation of Tangjiahui, Inner Mongolia, vitrinite accounts for 30.24% to 90.35% of the organic microscopic components, with an average content of 59.35%; it is mainly composed of homogeneous vitrinite (average content of 73.84%), followed by matrix vitrinite (average content of 24.49%), colloidal vitrinite (average content of 0.72%), and detrital vitrinite (average content of 0.94%), with a small amount of agglomerated vitrinite, as shown in Table 3.

[0092] Table 3 is the statistical content of microscopic coal rock components in Tangjiahui Coal Mine:

[0093]

[0094]

[0095] Characteristics of inertinite in coal

[0096] The inertin group of the 6th coal of the Taiyuan Formation of Tangjiahui, Inner Mongolia accounts for 7.68% to 64.91% of the organic microscopic components, with an average content of 34.51%. Among them, the content of semi-silky bodies is the highest (the average content is 50.15%), followed by silky bodies (the average content is 21.45%), the coarse-grained bodies are similar to the silky bodies (the average content is 20.88%), and it contains a small amount of detrital inertin bodies (the average content is 7.10%) and trace amounts of secretory bodies (the average content is 0.41%).

[0097] Characteristics of exinite in coal

[0098] In the 6th coal of Taiyuan Formation in Tangjiahui, Inner Mongolia, the exinite accounts for 0.00% to 18.46% of the organic microscopic components, with an average content of 6.13%. Among them, the cutinite content is the largest (average content is 83.50%), followed by the resin body content (average content is 13.87%), and the microspore content is relatively small (average content is 2.63%).

[0099] 3. Mineral characteristics of coal

[0100] Through microscopic coal rock determination, it was observed under a polarizing microscope that the coal of the Taiyuan Formation 6 of Tangjiahui, Inner Mongolia contains a large amount of clay minerals and a small amount of pyrite. The clay minerals are gray to gray-brown under reflected light, with an uneven surface and different distribution forms; the clay minerals are dispersed in the vitrinite, and some are filled in the inertinite (filled in the filamentous body cell cavity). The sulfide minerals in the Tangjiahui 6 coal are mainly pyrite, which appears yellow-white under reflected light, and some are whitish on the outside and yellow on the inside. They are usually roe-shaped, granular, irregular, and crack-filled, and are distributed in the vitrinite, such as Figure 3 shown.

[0101] The main minerals in the coal were analyzed by XRD and HighScorePlus software. The main minerals in the coal of the Taiyuan Formation 6 of Tangjiahui, Inner Mongolia are kaolinite, boehmite, dickite, pyrite, pyrite and pyrite. Among them, pyrite is generally believed to come from coal seams related to marine sedimentary environments, such as Figure 4 shown.

[0102] Example 7:

[0103] 1. Geochemical characteristics of trace elements in coal

[0104] The major elements in coal are generally expressed as major element oxides. Major elements are important components of coal-forming minerals. Major elements in coal can indicate the coal-forming environment. The media Al2O3, Fe2O3, CaO, and SiO2 are the main major elements in the coal of Tangjiahui Taiyuan Formation 6. The content of major elements in coal is obtained by X-ray fluorescence spectrometer (XRF), as shown in Table 4. The table shows that the content of major elements in the raw coal sample is: Al2O3 (53.57%) > SiO2 (34.04%) > Fe2O3 (2.32%) > CaO (1.37%) > TiO2 (1.00%)>Na2O(0.33%)>MgO(0.27%)>K2O(0.21%), among which the contents of Al2O3, SiO2, CaO, Na2O, MgO, TiO2 and K2O are all higher than those in Chinese coal, while Fe2O3 is lower than that in Chinese coal; the mineral composition of coal ash is mainly Al2O3 and SiO2, among which Al2O3 and SiO2 account for 58.57% and 34.04% respectively, and the composition of coal seam ash belongs to Al2O3-SiO2-Fe2O3-CaO type, indicating that more terrestrial minerals were transported to the study area. Based on this, it is speculated that the minerals of the mineable coal seams in the study area are mainly quartz and clay minerals, and the clay minerals are kaolinite and boehmite; CaO and MgO in coal mainly come from carbonate minerals;

[0105] Table 4 shows the oxide content of major elements in Tangjiahui 6 coal:

[0106]

[0107]

[0108] SiO2 / Al2O3 ratio

[0109] The Al2O3 content in the 6th coal seam of the Taiyuan Formation in Tangjiahui, Inner Mongolia, ranges from 45.68% to 67.87%, with an average of 53.57%, significantly higher than the Al2O3 content of Chinese coal. The SiO2 content ranges from 7.92% to 46.47%, with an average of 34.04%, also significantly higher than the SiO2 content of Chinese coal. The SiO2 / Al2O3 ratio ranges from 0.12 to 1.00, with an average of 0.67. Generally speaking, Si4+ in coal is mainly found in quartz and clay minerals, while Al3+ is mainly found in clay minerals. A high SiO2 / Al2O3 ratio in coal reflects the presence of silicon-rich minerals (such as quartz), while a low SiO2 / Al2O3 ratio is an important reason for the presence of aluminum-rich minerals (gibbsite, boehmite, and diaspore) in coal. The average SiO2 / Al2O3 in the Tangjiahui 6 coal in Inner Mongolia is 0.67, while the average SiO2 / Al2O3 in Chinese coal is 1.42, which is lower than the average in Chinese coal. This shows that there is a large amount of free Al2O3 or minerals containing Al2O3 in the Taiyuan Formation 6 coal seam of Tangjiahui, Inner Mongolia, and the free SiO2 and its minerals are relatively low. From the XRD mineral characteristic analysis, it can be seen that there are a large amount of kaolinite and boehmite in the Tangjiahui coal seam in Inner Mongolia, while the quartz content is relatively low. This is mainly attributed to the enrichment of Al-containing boehmite and kaolinite in the coal, and the low quartz content, so the SiO2 / Al2O3 ratio in the coal seam is relatively low.

[0110] Al2O3 / TiO2 ratio

[0111] The Al2O3 / TiO2 ratio can be used to determine the nature of the source rock in the source area. When the ratio is between 3 and 8, it indicates that the source rock is basic rock; when the ratio is between 8 and 21, it indicates that the source rock is neutral rock; when the ratio is greater than 21, it indicates that the source rock is acidic rock. As shown in Table 4, the Al2O3 / TiO2 ratio of coal sample 6 from the Taiyuan Formation in Tangjiahui, Inner Mongolia ranges from 25.99 to 169.96, with an average of 74.56. When the average value is greater than 21, it is believed that the parent rock in the study area is mainly composed of acidic rock.

[0112] 2. Trace element content characteristics

[0113] The trace elements in the 6th coal and roof and floor plates of the Taiyuan Formation of Tangjiahui, Inner Mongolia were tested by ICP-MS. The results are as follows: Figure 5As shown. The enrichment coefficient is usually used to express the degree of trace element enrichment in coal. The enrichment coefficient (CC) is the value of the trace elements in the test sample coal divided by the trace element content in the world coal. The enrichment degree of trace elements in coal can be divided into 6 levels: depletion, normal, slightly enriched, enriched, highly enriched and abnormally enriched. The judgment criteria are as follows: depletion when the enrichment coefficient is less than 0.5, normal when the enrichment coefficient is between 0.5 and 2, slightly enriched when the enrichment coefficient is between 2 and 5, enriched when the enrichment coefficient is between 5 and 10, highly enriched when the enrichment coefficient is between 10 and 100, and abnormally enriched when the enrichment coefficient is greater than 100.

[0114] According to the enrichment coefficient, the trace element enrichment status of the 6th coal of Tangjiahui Taiyuan Formation in Inner Mongolia is as follows: Sc is depleted, with a content of 0.84-2.93μg / g and an average content of 1.78μg / g; Cs is enriched, with a content of 1.84-9.51μg / g and an average content of 6.21μg / g; Ge is enriched, with a content of 2.90-101.30μg / g and an average content of 19.76μg / g; Zr is enriched, with a content of 20.72-739.50μg / g and an average content of 269.36μg / g; B is enriched, with a content of 225.23-565.58μg / g and an average content of 354.74μg / g. g; slightly enriched in Sn, with a content between 1.01 and 5.77 μg / g and an average content of 2.57 μg / g; slightly enriched in Ga, with a content between 11.13 and 33.54 μg / g and an average content of 21.09 μg / g; slightly enriched in Hf, with a content between 0.09 and 15.93 μg / g and an average content of 5.28 μg / g; highly enriched in Ta, with a content between 2.86 and 3.64 μg / g and an average content of 2.96 μg / g; highly enriched in Li, with a content between 43.91 and 213.10 μg / g and an average content of 136.57 μg / g; W, Bi, Nb, Rb and Sr are at normal levels.

[0115] The rare earth element Ce is depleted, with a content between 3.57 and 7.42 μg / g and an average content of 5.19 μg / g; Nd is slightly enriched, with a content between 17.36 and 39.64 μg / g and an average content of 25.24 μg / g; Gd is enriched, with a content between 16.87 and 37.68 μg / g and an average content of 23.14 μg / g; Dy is enriched, with a content between 14.01 and 31.02 μg / g and an average content of 18.48 μg / g; Ho is enriched, with a content between 3.31 and 6.45 μg / g and an average content of 4.52 μg / g; Sm is highly enriched, with a content between 27.04 and 54.75 μg / g and an average content of 34.59 μg / g; Eu is highly enriched. The REE content of Tangjiahui 6 coal is highly enriched, with a content ranging from 6.08 to 12.35 μg / g, with an average of 9.54 μg / g. Tb is highly enriched, with a content ranging from 2.84 to 6.28 μg / g, with an average of 4.25 μg / g. Er is highly enriched, with a content ranging from 9.97 to 20.22 μg / g, with an average of 13.07 μg / g. Tm is highly enriched, with a content ranging from 3.19 to 5.97 μg / g, with an average of 4.23 μg / g. Yb is highly enriched, with a content ranging from 13.13 to 34.82 μg / g, with an average of 21.32 μg / g. Lu is highly enriched, with a content ranging from 4.33 to 8.21 μg / g, with an average of 5.73 μg / g. La, Pr, and Y are within normal levels. The overall rare earth element content of Tangjiahui 6 coal is highly enriched, with relatively high contents.

[0116] Tl, Cd, Th, Cl, Cu, Mo, As, U, Cr, F, Be, Hg, Mn, Ag, Ni, Pb, Ba, Se, Co, Sb, V and Zn are harmful trace elements in coal. The mineral content is slightly enriched in Pb, with a content of 17.54-56.96μg / g and an average of 31.74μg / g; slightly enriched in Th, with a content of 0.60-26.76μg / g and an average of 8.11μg / g; slightly enriched in Mo, with a content of 4.28-13.06μg / g and an average of 9.15μg / g; slightly enriched in Be, with a content of 1.54-5.79μg / g and an average of 3.34μg / g; slightly enriched in Cr, with a content of 14.35-170.80μg / g and an average of 55.11μg / g; slightly enriched in Ni, with a content of 18. The content of Se is between 79 and 35.34 μg / g, with an average content of 26.40 μg / g; Se is slightly enriched, with a content between 0.26 and 23.34 μg / g, with an average content of 5.75 μg / g; Ag is highly enriched, with a content between 0.22 and 3.93 μg / g, with an average content of 1.52 μg / g; Zn is highly enriched, with a content between 94.72 and 914.20 μg / g, with an average content of 278.05 μg / g; Cd is highly enriched, with a content between 0.48 and 5.92 μg / g, with an average content of 2.37 μg / g; Cu, V, U and Co are at normal levels, while Tl and Ba are relatively depleted.

[0117] The average Li content of the Taiyuan Formation 6 coal in Tangjiahui, Inner Mongolia is 136.57 μg / g. The lithium content of the Tangjiahui 6 coal seam is higher than the average value of the world's coal and China's coal, reaching a highly enriched level, exceeding the comprehensive utilization grade proposed by Sun (120 μg / g), and has certain economic utilization value.

[0118] 3. Distribution characteristics of rare earth elements

[0119] The rare earth element (REY) content of Tangjiahui 6 coal ranges from 141.67 μg / g to 272.96 μg / g, with an average of 191.23 μg / g, exceeding the global REY average of 68.47 μg / g. The REY content of Tangjiahui 6 coal samples is significantly higher than the global average. The REY content in the roof of the 6 coal is 250.03 μg / g, while the REY content in the floor is 246.22 μg / g, both exceeding the REY content in the upper crust (168.37 μg / g). The mass concentration of LREY in coal is 57.19μg / g~101.40μg / g, with an average concentration of 76.73μg / g; the mass concentration of MREY is 48.63μg / g~99.12μg / g, with an average concentration of 65.65μg / g; the mass concentration of HREY is 35.84μg / g~75.67μg / g, with an average concentration of 48.86μg / g.

[0120] Rare earth element (REE) enrichment in coal occurs in three types: L-type (light REY), M-type (medium REY), and H-type (heavy REY). Based on REE data and upper crustal element standardization, the LaN / LuN, LaN / SmN, and GdN / LuN values ​​for the six coals and their roof and floor plates were calculated. The (La / Lu)N values ​​for the six coals and their roof and floor plates are all less than 0.02, with an average of 0.01. This numerical analysis indicates that the Tangjiahui six coals belong to the heavy rare earth (H) distribution type, enriching in heavy rare earths in marine sedimentary environments and light rare earths in terrestrial sedimentary environments. The Tangjiahui six coals belong to the heavy rare earth (H) distribution type, indicating heavy rare earth enrichment, indicating their provenance was marine sediments.

[0121] The rare earth elements were calculated using the δCe and δEu anomaly calculation formulas. The δCe and δEu values ​​of Tangjiahui 6 coal and floor coal samples were calculated using the following formulas:

[0122] δEu=EuN / (0.5SmN+0.5GdN)(1)

[0123] δCe=CeN / (0.5LaN+0.5PrN)(2)

[0124] The δEu values ​​of the Tangjiahui 6 coal range from 1.28 to 2.29, with an average of 1.60. The δEu values ​​of the roof and floor are 1.48 and 1.39, respectively, indicating a significant positive Eu anomaly. Negative Ce anomalies are influenced by a marine environment. Based on the negative δCe trend, the Zhiluo Formation coal environment is generally an oxidizing one. The δCe values ​​of the Tangjiahui 6 coal range from 0.13 to 0.32, with an average of 0.19. The δCe values ​​of the roof and floor are 0.17 and 0.16, respectively, indicating that the Tangjiahui 6 coal and its roof and floor have significant negative Ce anomalies, indicating an oxidizing environment influenced by a marine environment. A redox coal-forming environment can lead to Eu anomalies, with stronger oxidizing conditions leading to more pronounced negative Eu anomalies. The δCe / δEu ratio is used to determine the redox environment during deposition. A ratio greater than 1 indicates a predominantly reducing environment, while a ratio less than 1 indicates an oxidizing environment. The δCe / δEu values ​​for the Tangjiahui 6 coal sample range from 0.07 to 0.20, with an average of 0.12, indicating an oxidizing environment in the Tangjiahui mining area. A comprehensive analysis of (La / Lu)N, δCe, and δCe / δEu indicates that the Tangjiahui 6 coal formed in an oxidizing environment influenced by a marine environment.

[0125] 4. Occurrence status of trace elements

[0126] The coal samples were chemically extracted step by step using the Tessier five-step extraction method to obtain exchangeable ion state, carbonate-bound state, iron-manganese oxide state, organic-bound state, and residue state respectively; and the content of trace elements in each occurrence state was determined. In order to intuitively display the relative content of trace elements in each occurrence state, a percentage stacked bar chart was drawn, as shown in the following figure: Figure 6 shown.

[0127] The test results of Tessier's five-step extraction method show that carbonate-bound, organic-bound and residual states are the most active among the five occurrence states in the Taiyuan Formation 6 coal of Tangjiahui, Inner Mongolia. Sc, Zn, Rb, Mo, Cd, Sb, Cs, Ba, Ta, W, Re and Tl mainly exist in carbonate-bound state, Fe, Be, V, Cu, Ga, Se, Zr, Nb, Hf, Th and U mainly exist in organic-bound state, Ge, Ag, B and Co mainly exist in carbonate-bound and organic-bound states, Li, Cr and As mainly exist in residual state, Sr and Ag exist in carbonate-bound, organic-bound and residual states, Sn mainly exists in organic-bound and residual states, Cr exists mainly in residual state, and Pb exists mainly in iron-manganese oxidation state.

[0128] A comprehensive analysis of the occurrence states of the rare earth elements (REEs) reveals that they exist primarily in carbonate-bound states (31%), organic-bound states (27%), and residual states (24%), with some existing in ferromanganese-oxidized states (16%) and a small amount in exchangeable states (2%). Eu, Sm, Pr, Tb, Ho, Tm, Yb, and Lu exist primarily in carbonate-bound states, Gd and Er primarily in carbonate-bound and organic-bound states, Nd primarily in residual states, ferromanganese-oxidized states, carbonate-bound states, and organic-bound states, Dy primarily in organic-bound and carbonate-bound states, Ce primarily in residual states and ferromanganese-oxidized states, La primarily in residual states, and Y primarily in organic-bound states.

[0129] The mass fraction of the carbonate-bound state is between 0-100%, wherein all the Re (100%) elements exist in the carbonate-bound state, while the Th and Be elements do not exist in the carbonate-bound state; the mass fraction of the exchangeable state is between 0-25.55%, wherein the exchangeable state of the Ta element accounts for 25.55%, and W, Re, Tl, Pb, Th, U, Be, Co, Cu, Ga, Se, Zr, Ag, Cd, and Cs do not exist in the exchangeable state; the mass fraction of the ferromanganese oxidation state is between 0-45.14%, wherein the ferromanganese oxidation state of the PBa element accounts for 45.14%, and Re and Sb do not exist in the ferromanganese oxidation state; the mass fraction of the organically bound state is between 0-86.15%, wherein the organically bound state of the Zr element accounts for 86.15%, and Re and Sb do not exist in the organically bound state; the mass fraction of the residual state is between 0-92.49%, wherein the residual state of the As element accounts for 92.49%, and W and Re do not exist in the residual state. Aluminosilicate minerals are usually in residual state. The aluminosilicate minerals of Tangjiahui 6 coal are mainly kaolinite and boehmite, indicating that Nd, Cr, Ce, La, Li, Cr and As are mainly contained in kaolinite and boehmite.

[0130] Example 8:

[0131] Coal deposition environment characteristics

[0132] 1. Paleosalinity characteristics

[0133] Paleosalinity refers to the degree of salinity in sediments. There are many geochemical indicators for analyzing paleosalinity. The paleosalinity of Tangjiahui 6 coal is determined by studying the Ba content and the Sr / Ba ratio. The Ba content of Tangjiahui Taiyuan Formation 6 coal in Inner Mongolia ranges from 225.23 μg / g to 565.58 μg / g. Figure 7 As shown in A, the average value is 354.74 μg / g, and the Ba content is greater than 110 μg / g. The overall sedimentary environment is saline water. The Sr / Ba ratio of the 6 coal in the Taiyuan Formation of Tangjiahui, Inner Mongolia is 0.25-4.99. Figure 7As shown in Figure B, the average value is 1.61. The Sr / Ba ratio in the coal gradually decreases from bottom to top. Among them, the ratios of samples TJH-9 to TJH-12 are 0.25, 0.72, 0.77 and 0.64, all of which are less than 1, indicating that they were formed in a brackish water sedimentary environment. The Sr / Ba ratios of the remaining coal samples are all greater than 1, indicating a marine sedimentary environment. Therefore, the Tangjiahui 6 coal belongs to a marine sedimentary environment. According to the Ba content analysis above, the mining area belongs to a brackish water sedimentary environment. Combined with the Sr / Ba ratio analysis, the study area is a marine sedimentary environment, indicating that the coal-forming environment in the study area was influenced by the marine brackish water sedimentary environment.

[0134] 2. Paleoclimate

[0135] The Sr / Cu ratio of the 6th coal of the Tangjiahui Taiyuan Formation in Inner Mongolia is 0.95-7.60. Figure 7 As shown in Figure C, the average value is 3.48, showing a downward trend from bottom to top, followed by an increase, a decrease, and then an increase. The Sr / Cu ratio indicates that the Tangjiahui coal mine was primarily formed during a humid climate. During the deposition of the Taiyuan Formation, there was a period of drought, followed by a transition to a warm and humid climate.

[0136] The CaO / (MgO×Al2O3) ratio can reflect the relative temperature. The average CaO / (MgO×Al2O3) ratio of the Tangjiahui Taiyuan Formation 6 coal is 0.0866.

[0137] 3. Ancient redox environment

[0138] In the paleo-redox environment, the V / (Ni+V) ratio between 0.83 and 1 indicates a tranquil marine environment, the ratio between 0.57 and 0.83 indicates an anoxic environment, the ratio between 0.46 and 0.57 indicates an oxidizing environment, and the ratio less than 0.46 indicates a more oxidizing environment. The V / (V+Ni) ratio of the Tangjiahui 6 coal is between 0.43 and 0.58. Figure 7 As shown in D, the average value is 0.51, and the overall value ranges from 0.46 to 0.57, reflecting that the water environment in the study area was an oxidizing environment during the coal-forming period.

[0139] The U / Th ratio can also reflect the redox characteristics. When the U / Th ratio is less than 0.75, it indicates that the sedimentary water body is in an oxidizing environment; when the U / Th ratio is between 0.75 and 1.2, the sedimentary water body is in a weakly oxidizing environment; when the U / Th ratio is greater than 1.2, the sedimentary water body is in an anoxic environment

[108] . The U / Th ratio of the 6th coal of the Taiyuan Formation of Tangjiahui, Inner Mongolia is between 0.01 and 3.06. Figure 7As shown in Figure E, the average value is 0.70, and the overall value is less than 0.75, reflecting that the water environment in the study area was generally oxidizing during the coal-forming period. The δCe and δCe / δEu ratios also indicate that the water environment in which the Tangjiahui 6 coal formed was oxidizing. Comprehensive analysis shows that the water environment in which the Tangjiahui 6 coal formed was oxidizing.

[0140] This application first determines the sedimentary environment characteristics of coal based on the δCe / δEu, U / Th, V / (V+Ni), Sr / Ba, B, and Sr / Cu indicators. Ba reflects the sedimentation method, the Sr / Ba ratio determines the sedimentary environment, Sr / Cu determines the temperature and climate, and V / (V+Ni), U / Th, δCe and δCe / δEu reflect the oxidation environment. Subsequently, the coal sample information after detection and analysis is combined with the collection site information and put into the constructed three-dimensional model to facilitate subsequent inquiries on the progress of the coal sample information and provide research data for subsequent researchers.

[0141] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A method for analyzing environmental geochemical characteristics of coal trace elements, characterized in that: The following steps are involved: S1 collects coal seam map information at the current location and uses Tableau software to build a 3D map model of the current location; S2 extracts sample sampling points on the constructed three-dimensional map model and calibrates the sample collection point information; S3 collects samples at the corresponding positions of the sample sampling points and pre-processes the collected samples; S4 tests and analyzes the pre-treated samples and collects sample test information; S5 performs coal quality and coal rock characteristic analysis based on the sample test information obtained; S6 performs geochemical characteristic analysis of coal elements based on the sample test information obtained; S7 performs coal deposition characteristic analysis based on the sample test information obtained from the test; S8 integrates the sample analysis content with the sample collection point information and injects it into the 3D map model; The sample collection point information in step S2 includes sample name, sample coordinates and sample depth information; The sample test information in step S4 includes basic physical and chemical property information, trace element information, major element information, mineral information, organic component information and occurrence state information of the sample coal; The coal quality and coal rock characteristics in step S5 include coal quality characteristics, coal rock characteristics and coal mineral characteristics; The coal element geochemical characteristics in step S6 include the content characteristics of major elements, the content characteristics of trace elements, the distribution characteristics of rare earth elements and the occurrence state of trace elements; The coal deposition characteristics in step S7 include paleo-salinity characteristics, paleo-climate characteristics and paleo-redox environment characteristics.

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