Trace Elements In Coal Research Articles

Study on the correlation between trace elements in coal and coal-forming plants: a case study

ABSTRACT For this study, coal samples were sourced from the Yan’an Formation (J2y), a middle Jurassic coal formation in the Northern Shaanxi province in China. We investigated the correlations between trace elements in coal and occurrence of coal-forming plants (CFPs) in an effort to determine the relationship between the abundance of CFPs and trace elements in the coal formation. Twenty-one trace elements (Be, B, P, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Mo, Ag, Cd, Ba, Hg, Tl, and Pb) in coal were determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The enrichment characteristics of trace elements in coal were performed by using concentration coefficient value. CFPs were identified and measured by analyzing spore-pollen in the coal samples. Correlation analyses between trace elements in coal and CFPs were conducted using the SPSS 21 software package. Our results indicated that the coal formation contains an enriched concentration of Cd, slightly enriched concentrations of Zn and Ag, low concentrations of V and Mo, normal concentrations of the other 16 trace elements. CFPs identified in the samples included 17 families (Cupressaceae, Cyatheaceae, Cycadaceae, Dicksoniaceae, Dipteridaceae, Ephedraceae, Equisetaceae, Ginkgoaceae, Gleicheniaceae, Lycopodiaceae, Lygodiaceae, Osmundaceae, Pinaceae, Pteridaceae, Podocarpaceae, Polypodiaceae, and Taxodiaceae). Polypodiaceae is the richest in Pteridophyta. Ginkgoaceae, Cycadaceae, and Podocarpaceae were richer in Spemaiophyla. Those with a correlation coefficient more than 0.5 were found between the following: (i) Be, Sr, and Equisetaceae; (ii) V, Ni, and Cu, and Polypodiaceae; (iii) P and Ginkgoaceae; and (iv) Ba, Pb, and Cupressaceae. Significant negative correlations were found between the following: (i) Ni, Cu, Ba, Pb, and Osmundaceae; (ii) Sr and Polypodiaceae; and (iii) Sr and Ginkgoaceae.

Spatial Macroscale Variability of the Role of Mineral Matter in Concentrating Some Trace Elements in Bituminous Coal in a Coal Basin—A Case Study from the Upper Silesian Coal Basin in Poland

As there are numerous claims that the mode of occurrence of trace elements in coal influences the quality of the substrates as well as the course and results of the coal preparation processes, it is necessary to analyse the differences in the mode of occurrence of the elements in coal within a coal basin or a coal deposit. With the use of concentration distribution functions and the Pearson correlation coefficient, it was concluded that (1) mineral matter plays a significant and nearly constant or constant role in concentrating V, Cr, Co, As, Rb, Sr, Ba, and Pb in coal; (2) organic matter plays a stable role in concentrating Sn; and (3) there are significant differences in the role of organic and mineral matter in concentrating Mn, Ni, Cu, Zn, Mo, Cd, and Sb in coal throughout the USCB (Upper Silesian Coal Basin). Moreover, there was observed a difference in the mode of occurrence of Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, and Sb in coal in the vertical profile of the USCB. At the same time, there were observed no differences and a stable significant role of mineral matter in concentrating V, As, Rb, Sr, Ba, and Pb in coal, while the role of the petrographic groups of the coal components in concentrating the elements in raw coal was differentiated. It is believed that the difference in the mode of occurrence of the trace elements in coal within coal seams and coal deposits is a geochemical regularity.

Chemical deactivation of Selective Catalytic Reduction catalyst: Investigating the influence and mechanism of SeO2 poisoning

Selenium (Se) is a major trace element in coal that can easily volatize and become part of flue gas during the combustion process. Currently, the interactions between SeO2 and Selective Catalytic Reduction (SCR) catalysts remain unclear. In this study, a field test at four coal-fired power plants found that the Se concentration at the SCR inlets were relatively high, with more than 95% present in its gaseous phase. To explore possible interactions between SeO2 and SCR catalyst, a V2O5-WO3/TiO2 (VWTi) catalyst was subjected to various degrees of in situ SeO2 poisoning. A positive correlation between the decreases in catalytic activity and N2 selectivity and an increasing amount of SeO2 deposition was observed. The decreases in NH3-adsorption capacity and strong acid sites activation ability were responsible for the loss in catalytic activity, while higher ratio of chemisorbed oxygen and stronger reducibility resulted in NH3 being oxidized to N2O and N2 selectivity loss. Based on these results, it is clear that SeO2 poisoning of SCR catalysts should be taken into consideration to ensure the reliable operation of SCR systems.

Quantitative Study of Trace Elements in Coal and Coal Related Ashes using PIXE

ABSTRACT Trace element analysis of feed coal, fly ash and bottom ash samples acquired from NTPC, Visakhapatnam was done by Particle Induced X-ray emission (PIXE) method. Sixteen inorganic elements K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb were quantified. The enrichment and partition ratios were determined to understand the distribution and behavior of trace elements in coal and its residues. Enrichment factor for trace elements in ashes with respect to the concentration of Fe normalized relative to the earth’s continental crustal values was calculated to understand the effect of these elements on the environment. It was expected that the results of the present study may be useful in determining the coal combustion residue recovery potential and also help in reducing their potential impact on eco systems.

A comparison study of Singareni and Talcher coal samples through elemental analysis using PIXE technique

A comparative study of trace elements in Singareni and Talcher coals was carried out using Particle Induced X-ray Emission technique with a 3 MeV proton beam. Concentrations of sixteen elements, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr and Pb were obtained and compared with Clarke’s values to ascertain the enrichment factor for each. Pearson correlation and hierarchical cluster analyses were used to understand the relationship between the inorganic constituents of coal. It is anticipated that this study of trace elements in coals will be useful to protect environment and to regulate the emission of toxic elements during coal combustion and utilization.

Distribution characteristics and migration patterns of hazardous trace elements in coal combustion products of power plants

Trace elements in coal produce migration and enrichment after combustion, the enrichment and release of hazardous trace elements will cause effective harmful to human health and the environment. In this paper, the distribution characteristics and occurrence state of hazardous trace elements in coal combustion products were studied by measuring the concentration of harmful trace elements in coal, slag, coarse ash, fine and fly ash. The experimental study of step-by-step chemical extraction was carried out, the migration and transformation model of trace elements in coal combustion process was investigated. The results show that the trace elements are easily enriched in fine particles of coal ash. The occurrence state of elements in combustion products has changed obviously, and the concentration of residual state has increased for example aluminosilicates. According to the enrichment index REI (Relative Enrichment Index), hazardous elements can be classified into three categories: (I) The elements left in both solid waste slag and fly ash are Cr, Mn and Ni (REI > 0.85); (II) The elements left in solid waste are Be, Co, Cu, Zn, Cd, Ba, Pb and U (0.1 < REI < 0.85); (III) The elements mainly volatilized into the atmosphere are few, only Sb (REI < 0.1).

Concentration Levels of Industrially Valuable Trace Elements in Coals

The concentration levels of valuable (rare, rare-earth, noble, nonferrous, radioactive, etc.) metals in coals were studied for the preliminary assessment of their possible industrial importance. With consideration for the similarity of the composition of the mineral matrix of coal or coal ash to the trace-element composition of the industrial types of ores (silicates, sulfides, and placers), the use of the minimum industrial concentrations of elements was proposed for the above assessment of the trace elements of coal.

Distribution of Trace Elements in Brown Coals from the Amur River Region and in Their Submicron Fractions

It was established experimentally that the trace elements that are present in brown coal samples in low and ultra-low concentrations are concentrated in the finest fraction of the samples whose particle size is smaller than 1 μm (in a submicron fraction), which was separated using special nanotechnological techniques. A comparative analysis of the concentrations of chemical elements in the gross samples of coal and in the submicron fractions showed the special features of the distribution of trace elements in a coal matrix and prospects for the extraction of potentially valuable elements from coals.

Investigation of Environmental-Concern Trace Elements in Coal and Their Combustion Residues from Thermal Power Plants in Eastern India

The bituminous-to-sub-bituminous quality feed coals of thermal power plants contain several environmental-concern trace elements (As, Se, Ni, Cr, Zn, Pb, Cu, Cd, Co and Mn). During combustion, these elements are enriched or depleted in the major coal combustion residues (CCR, fly and bottom ash). The analyzed elements are classified into three different groups according to the estimated enrichment ratio and relative enrichment index. Class I contains the volatile elements As, Se, both of which are depleted in fly and bottom ash. Class II contains the semi-volatile elements Zn, Cu, Ni, Cr, Cd and Pb, which are more enriched in finer fly ash than coarse bottom ash. In contrast, the less volatile Class III elements Co and Mn are equally enriched in fly and bottom ash. The major CCR containing heavy load of these elements (about 1826 t/year) are gradually exposed to the different segments of environment such as air, water and soil. These elements may have a possibility to be bioavailable in the food chain, which may give harmful influence to the ecological receptors. As per risk assessment code, the analyzed elements As, Se, Cr and Ni have low-risk character, while rest of the elements Cd, Cu, Pb, Zn, Co and Mn are safe for the environment. Laboratory water leaching experiment of elements in fly ash and bottom ash shows that these combustion residues are non-hazardous and may be used in various sectors such as construction field, land filled materials, mine reclamation and also in agriculture field. An understanding of regular monitoring and skillful management for the disposal practice as well as environmentally safe utilization of combustion residues generated from thermal power plants is a crucial issue from public health viewpoint.

Modes of Occurrence of Cr, Co, Ni, Cu, Cd, and Pb in the Main Coal Seams of Southwestern China’s Nantong Coalfield

The modes of occurrence of trace elements in coal reveal essential information about environmental impact during coal exploitation and utilization. Utilizing improvements on a recently published sequential leaching protocol, this study investigated the modes of occurrence of Cr, Co, Ni, Cu, Cd, and Pb (water-soluble, ion-exchangeable, carbonate-bound, sulfide-bound, organic-bound, and silicate-bound) in coal samples collected from the Nantong coalfield in southwestern China. Results suggest the improved method favorably affected the sequential leaching experiment. The ashing temperature did not exceed 390°C and did not damage the structure of the silicate minerals, facilitating the effective extraction of trace elements within the organic matter. The case study in the Nantong coalfield demonstrated that the water-soluble and ion-exchangeable fractions account for only a small portion of the six elements. Specifically, chromium exhibited affinities with carbonates and silicates. The percentages of different target fractions for cobalt varied significantly in different samples. Nickel was almost evenly distributed in the fractions of carbonates, sulfides, organic matter, and silicates. For cadmium, silicate was the main fraction, followed by sulfides. Lead predominantly appeared in carbonates and sulfides. The correlativity of different elements in the corresponding fractions revealed carbonates and sulfides as the primary carriers for all six elements, followed by silicates and organic matter. Overall, Cr, Co, Ni, and Cu exhibited very close relationships and similar distribution patterns in different coal samples. Organic-bound Cr, Co, and Ni were noticeable in the No. 4 and 6 coal seams, though they were not the dominant fractions. The affinity between Pb and Cd indicated they have similar modes of occurrence.

Modes of occurrence of ecotoxic elements in coal from the Upper Silesian Coal Basin, Poland

Optical microscopy, x-ray diffraction and selective x-ray fluorescence spectrometry, SEM/EDS and laser ablation-micro-ICP-AES have been used to study the minerals and the concentrations of 15 trace elements in coal from the Upper Silesian Coal Basin. Mineral matter has a significant impact on the contents of V, Cr, Co, Cu, As, Rb, Sr, Cd, Ba and Pb in coal and organic matter on the contents of Ni, Zn, Mo, Sn and Sb in coal. Contents of V, Cr, Cu, Rb, Sr and Ba are most probably dependent on clay minerals and those of V and Rb on both clay minerals and vitrinite. Organic matter and carbonate minerals likely determine contents of Mn, and mineral matter and vitrinite likely determine contents of Co and Pb are probably influenced by sulphides. The bulk of the V, Cr, Mn, Co, Ni, Cu, Rb, Sr, Mo, Sb and Ba in the coal is probably of syngenetic origin. In contrast, the contents of Zn, As, Cd and Pb and, to a degree, those of Mn, Ni, Mo and Sb are epigenetic. Analysis results in the micro-area of minerals from bituminous coal reveal that the greater the heterogeneity of disulphides and of their association with carbonates and the more this heterogeneity applies to epigenetic minerals, the higher the contents of Ca, Cr, Mn, Ni, Zn, Cd and Pb. Diagenetic carbonates have higher contents of Cr, Mn and Ni, and smaller contents of Ca, Zn, Cd and Pb than the epigenetic minerals. These characteristics can be important from an ecological perspective; they identify which mineral matter components are best removed from coal to make it more suitable for combustion and in chemical processing.

Investigating the occurrences of valuable trace elements in African coals as potential byproducts of coal and coal combustion products

There is a growing attention in valuable trace elements (TEs) in coal and coal combustion products as they can potentially be future resources of valuable TEs. Therefore, understanding the mode of occurrences of valuable TEs in coal has several advantages for their economical and industrial extractions. Since there is limited information on the affinity of valuable TEs in the structure of African coals, this study explores correlations between conventional coal properties and concentration of vanadium, yttrium, gallium and lithium as valuable TEs for a wide range of African coal samples (139 samples) from South Africa, Botswana, Egypt, Tanzania, Nigeria and Zambia by statistical methods. Statistical assessments indicated that the concentrations of Y, V, Li and Ga for these countries are higher than their value in the world coal (on average). The outcomes of assessments showed that the Li, Ga and V are associated with the mineral matter fraction (inorganic affinity) of the coal where they have significant positive correlations with ash and Al (as a major element) and potentially clay minerals are their main bearing minerals. However, statistical explorations suggested that Y may have both the organic and inorganic occurrences in the African coal samples.

In seam variation of element-oxides and trace elements in coal from the eastern Ordos Basin, China

This paper investigated the mineralogical and geochemical compositions of the upper Pennsylvanian coal from Hedong Coalfield, in the eastern Ordos basin, China, using SEM, XRD, ICP-MS, ICP-CCT-MS, DMA-80 and ISE methods. The bituminous coal samples were collected form Nos. 3 and 4 Coal, which had low ash yield and were medium volatile, and had low sulfur content and low hazardous trace elements concentrations (Be, F, As, Hg, U and Pb). Maceral compositions were dominated by vitrinite (up to 90.2%), and to a lesser extent by inertinite and liptinite, all subgroups were detected in the coal samples. Minerals included quartz, clay minerals, sulfide and other oxide minerals. SiO2 and Al2O3 were the dominant major elements-oxides in both coal seams with much higher concentrations than in Chinese coal, while other major elements-oxides (Na2O, K2O, Fe2O3, MgO) had average values compared to Chinese coal. No. 3 Coal was enriched in Li and Zr, and No. 4 Coal was enriched in Li, Be, Cu, Se, and In. Elemental occurrence was studied using statistical methods, and Li, Rb, Zr, Cs, Ba, Hf, Tl, Pb, and Th were inorganic affinities, while F, V, Cr, Ga, Ni, As, In, Ta occurred as inorganic–organic affinities and Fe and S may have occurred in pyrite. Coal facies indicators (GI, TPI, GWI, and VI) plots suggested that the two coal seams were deposited in different environments: No. 3 Coal was deposited in a wet forest swamp, while No. 4 Coal was formed in a mesotrophic to ombrotrophic environment. The geochemistry of these coal samples (Al2O3/TiO2, TiO2/Zr, Zr/Sc and Th/Sc ratios) indicated that the coal samples sediment was sourced from intermediate and felsic igneous rocks.

Distribution of trace elements in coal and coal fly ash and their recovery with mineral processing practices: A review

Today coal is among the most important energy sources. In order to meet the world's energy demands, low-calorie lignite with a high ash content is generally used in the large capacity coal-fired thermal power plants. As a result of coal firing, wastes such as fly ash, slag, and flue gas are also produced. Subsequently, toxic trace elements within coal are transferred to wastes such as slag, fly ash, and flue gases. Large amounts of these, which are usually stored in collection ponds or stockpiles, are problematic in terms of environment. Although coal fly ash (CFA) has been utilized in construction and several other industries for decades, its current ratio of utilization is still quite limited. As an important fact, CFA also contains many valuable metals including germanium (Ge), gallium (Ga), vanadium (V), titanium (Ti), and aluminum (Al). In addtion, coal and CFA can be regarded as alternative sources of radioactive elements. Therefore, they also have a great potential in terms of the precious metals and trace elements they contain. In this study, the present literature on the distribution of trace elements in coal and coal ash during firing and ore preparation processes and their recovery possibilities with mineral processing practices are reviewed. While many research works on the subject clearly indicate that the large amounts of the ashes produced from firing of coal could be problematic in terms of environment, many studies and practices also show that coal combustion products also have a great potential in terms of the precious metals and trace elements.

Chemical speciation and leaching characteristics of hazardous trace elements in coal and fly ash from coal-fired power plants

This work reports the chemical speciation and leaching characteristics of seven hazardous trace elements (HTEs, including Hg, As, Cr, Cd, Ba, Mn, and Pb) in the coal and fly ash samples collected from four coal-fired power plants in China. The physical structure and chemical composition of the fly ash were characterized by the scanning electron microscope (SEM) and the energy dispersive X-ray spectrometer (EDX). The chemical speciation of HTEs in the coal and fly ash was measured by the modified three-step sequential extraction method, proposed by the European Community Bureau of Reference (BCR). Leaching characteristics of HTEs in the fly ash were investigated by a single batch leaching test. The concentration of HTEs in solid and liquid samples was determined by the direct mercury analyzer DMA 80 (Hg in solid) and the inductively coupled plasma-mass spectrometry (ICP-MS). Results show that for the coal, concentration of Hg, As, Cr, Cd, Ba, Mn, and Pb is 0.06–0.22, 0.63–4.01, 8.91–13.09, 0.06–0.15, 108.67–229.21, 49.94–100.24 and 6.74–26.38 mg/kg, respectively. Mercury is mainly in the residual form while Cd and Ba are primarily in reducible form. Compared with other HTEs, manganese in water/acid soluble and exchangeable fraction has the large percentage. For the fly ash, the concentration of Hg, As, Cr, Cd, Ba, Mn and Pb is 0.17–1.26, 5.15–25.74, 43.25–64.61, 0.56–0.70, 777.05–970.70, 163.83–831.47 and 28.94–119.57 mg/kg, respectively. Mercury and chromium are mainly in the residual speciation. Arsenic and manganese in water/acid soluble and exchangeable form have high ratio with value of 7.27–58.60% and 6.14–62.27%, respectively. Cadmium and barium are primarily in the reducible form. Based on the risk assessment code, manganese in the coal can pose high or very high risk on the environment. Leaching concentration of Cr in some fly ash is higher than permissible limits and the pH value of leaching solution for the fly ash is alkaline. Considering huge fly ash production from coal combustion and complex landfill conditions, some suitable disposal measures to minimize the risk on the environment are needed.

Geochemistry of elements associated with Late Permian coal in the Zhongliangshan mine, Chongqing, Southwest China

The enrichment and geochemical significance of elements associated with Late Permian coals in Southwest China have always gained widespread interest in the field of coal geology. The present study focuses on the geochemical characterization of Late Permian coal in the Zhongliangshan mine. Twenty-three samples were collected from the K1a coal seam of the Zhongliangshan mine, and the major and trace elements in the coal were analyzed by using X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry. The composition of minerals in the Zhongliangshan coal, and the modes of occurrence of coal-associated elements, especially those with elevated contents, were studied through a combination of microscopic analyses, X-ray powder diffraction, and scanning electron microscope – energy dispersive X-ray spectrometer. The minerals in coal mainly consist of kaolinite, pyrite, calcite, and quartz, as well as small amount of gypsum and anatase. Compared with the average elemental concentrations in world coal, the Zhongliangshan coal is enriched in Cr, and slightly enriched in Li, U, Sr, V and Ag. Combining the correlation analysis and sequential chemical extraction experiments, it can be inferred that many trace elements in the Zhongliangshan coal have both inorganic and organic affinities. The elements Cr, Li, and V mainly occur in clay minerals, and also are related to organic matter in the coal. Uranium presents firstly in the organic and then silicate states. Strontium shows multiple modes of occurrence including carbonate, silicate, and exchangeable ion states, and Ag primarily occurs in sulfides followed by silicates. The terrigenous debris input from the Emeishan basalt is the major reason for the enrichment of above elements in the Zhongliangshan coal.

Mapping of Trace Elements in Coal and Ash Research Based on a Bibliometric Analysis Method Spanning 1971–2017

Coal is the most important fossil energy used in China. The environmental impact of trace elements released in coal combustion has become one of the hottest issues in recent years. Based on a software named CiteSpace, and social network analysis (SNA), a bibliometric analysis of research into trace elements in coal and ash field during 1971–2017 is presented with the information of authors, countries, institutions, journals, hot issues and research trends in the present study. The study results indicate that: (1) Shifeng Dai, Robert B Finkelman, Guijian Liu and James C Hower have a large number of publications with great influence. (2) China (29.8%) and USA (22.2%) have high productivity in total publications. China and the USA correlate closely in the cooperative web system. (3) China University of Mining and Technology and Chinese Academy of Sciences take the leading position in the quantity of publications among all research institutions. (4) Energy and fuels, engineering and environmental science are three disciplines with the most studies in this field. (5) International Journal of Coal Geology, Fuel, Energy and Fuels and Fuel Processing Technology are the top four journals with the most publications in this field. (6) The enrichment origin and modes of occurrence of trace elements are the mainstream research related to trace elements in coal and ash. The environmental problems caused by coal combustion have promoted the development of trace elements in coal research, and human health is getting more and more popular in recent years. The study findings provide a better understanding of features of trace elements in coal and ash research, which could be taken as a reference for future studies in this field.

Volatilization of mercury in coal during conventional and microwave drying and its potential guidance for environmental protection

During the thermal drying process of coal, the sufficient attention has been paid to the changes in the properties of coal before and after the drying process. However, the volatility characteristics of harmful trace elements in coal during the drying process are always neglected to date, whereas the volatilization of harmful trace elements not only has significant effects on the surrounding atmosphere environment but also influence the following utilization of dried coal. In this study, the volatility characteristics of both the moisture and mercury in the coal sample during conventional (electric blast oven) and microwave (microwave oven) drying processes were investigated. In addition, the changes in the surface properties of coal before and after the drying process were studied using X-ray photoelectron spectroscopy (XPS) analysis. The results show that the moisture content of coal decreases in non-line format (decreases slowly at the first and then quickly according to the drying time) in the conventional drying process, while it decreases in line format in the microwave drying. The microwave drying process needs much shorter time required to obtain the dried coal of a certain moisture content than the conventional drying process. Under the same volatilization rate of moisture, the volatilization rate of mercury in the microwave drying process is always greater than that in the conventional drying process. Nearly half or more (49.73% and 59.26%, respectively) of the mercury in the coal slime evaporates into the atmosphere after the drying processes. XPS results show the content of CC and CH groups on the coal surface increased, but the CO content decreased after the drying processes and the microwave drying process has a stronger ability to remove oxygen-containing functional groups than the conventional drying process.

Construction of Trace Element in Coal of China Database Management System: Based on WebGIS

The combination of geographic information system and mineral energy data management is helpful to promote the study of mineral energy and its ecological damage and environmental pollution caused by its development and utilization, which has important application value. The Trace Elements in Coal of China Database Management System (TECC) is established in this paper, applying the techniques of B/S three-layer structure, Oracle database, AJAX and WebGIS. TECC is the first database system which aims at managing the data of trace elements in coal in China. It includes data management and analysis module, document management module, trace elements in coal data maintenance module and authority management module. The data entry specification is put forward in the present study and the spatial data is included in TECC system. The system achieves the functions of data query, analysis, management, maintenance and map browsing, thematic map drawing as well as satellite video display, which lay the foundation for the analysis of large data of trace elements in coal. It is a practical platform for the acquisition, management, exchange and sharing of trace element research and geochemical research data of coal.

Electron probe microanalysis of major and trace elements in coals and their low-temperature ashes from the Wulantuga and Lincang Ge ore deposits, China

The world-class coal-hosted Ge ore deposits of Wulantuga (Inner Mongolia) and Lincang (Yunnan Province) in China display unusually high concentrations of some trace elements, including Be, Ge, As, Sb, Nb, W, and U. In coal, these elements may be associated with the macerals and/or with the inorganic fraction (e.g., minerals and amorphous phases). Distinguishing among different associations is important for practical applications, but still challenging. In this study, an in situ electron probe micro-analysis (EPMA) technique was applied in order to map the distribution of both light elements (C, O, and S) and selected trace elements (Wulantuga: Ge, W, and As; Lincang: Ge, W, As, and U) in the high-Ge lignite samples and their low-temperature ashes (LTAs). The EPMA detection limit was stable for these light and trace elements commonly associated with organic matter, so that reliable point analysis data were acquired for individual macerals. Additional mineralogical and geochemical data were obtained by petrographic microscopy, XRD, EDS, and ICP-MS analyses. WDS in situ element mapping and point analysis demonstrate that the huminite in the Wulantuga coal has a lower C content and higher O and S contents relative to inertinite, and Ge, As, and W show a preferential enrichment in huminite. Among the different huminite macerals in both the Wulantuga and Lincang coals, Ge, As, W, and U tend to occur in more compact huminites (ulminite or gelinite), and their abundances show mild to considerable variations across the compact huminites. The in situ concentrations of Ge and W display a direct correlation, suggesting their co-affiliation with organic matter. Elements such as Ge, W, and U have a considerable organic affinity, with a minor fraction associated with inorganic S-rich phases, such as iron sulfide/sulfate (e.g., pyrite and copiapite). Arsenic has a mixed affinity to organic matter and iron sulfide/sulfate. No Ge minerals have been detected in the LTAs, and Ge in the LTAs is likely to exist in an inorganically amorphous state. This study could provide new perspectives on the modes of occurrence of trace elements concerned in the coal-hosted germanium ore deposits in China.