Xinguo Zhuang

Geological controls on the mineral matter and trace elements of coals from the Fuxin basin, Liaoning Province, northeast China

Abstract This study summarizes the results of geological, petrographical, geochemical and mineralogical studies performed to determine the geological controls on coal quality of the Fuxin deposit, Liaoning Province, in northeast China. The study is focused on the Haizhou mine, which currently mines a coal-bearing clastic Lower Cretaceous series affected by a diabase intrusion. Three major coal seams are differentiated: the Taiping, the Middle and the Shunjawan. Fuxin coal is a high quality coal with low ash and sulphur contents (4.0 to 18.0% HTA and 0.3 to 0.8%S tot ) and high calorific value (5600 to 7500 cal/g, as received basis). Coal impurities (both major and trace elements) are at very low concentrations; only a high Mn concentration (up to 8600 ppm) was detected. The rank of Fuxin coal (mainly high volatile B-bituminous coal) is clearly influenced by the diabase intrusion, which has induced the formation of natural coke from coal. Natural coke surrounds the diabase dykes and sills with a thickness ranging from a few centimetres up to 1.5 m. In addition, a wide aureole made up of high volatile A-bituminous coal formed around the coke. The diabase intrusion was not a major source of elemental mobilization, Mn being the only element clearly enriched in the coal (by 1 to 2 orders of magnitude). However, major changes in major and trace element distribution (affinities) were induced in the coal by the intrusion. The geochemical study revealed that these changes were the consequence of the mobilization of organic-, sulphide- and carbonate-associated elements.

Mineralogy and geochemistry of coal from the Liupanshui mining district, Guizhou, south China

Abstract This study focuses on the geochemistry and mineralogy of 23 coal seams from the Shuicheng and Luizhi coal fields from the Late Permian Liupanshui coal mining district, in the west of Guizhou province in southern China. Coal rank ranges widely from high volatile bituminous to low volatile bituminous and anthracite. Major mineral phases present in the Liupanshui coal are kaolinite, quartz, pyrite, and calcite. Traces of other primary minerals are marcasite, gypsum, and dolomite. The Shuicheng coal usually has higher kaolinite and quartz contents than the Luizhi coal. Marcasite occurs indiscriminately in the different coal seams without a clear distribution pattern. The presence of other minerals, such as rutile, anatase, tourmaline, zircon, and phosphates, was also noted. The total sulphur content of Liupanshui coals is higher in the marine-influenced coal seams (up to 7.5% dry), and lower in the nonmarine-influenced coals (as low as 0.3%). In the Luizhi coal field, the coal is characterised by a high sulphur and iron content, whereas in the Shuicheng coal field, contents varied from low to high, depending on the coal seams. An inverse geochemical distribution was detected for the mean contents of Ca–Mn–Ge, with lower contents in the Luizhi coal field. The Liupanshui coals are characterised by relatively high contents of Mn, V, Cu, Li, Zr, Nb, Hf, Ta, Tl, Th, and U, when comparing with the usual concentration ranges in bituminous coals. Trace elements in coals from Liupanshui showed narrow variations in their concentrations among coal seams and coal. Three major trace element affinities (aluminium-silicates, sulphides, and carbonates) accounted for the occurrence and distribution of most of the elements studied were determined.

Petrology, mineralogy and geochemistry of the Permian and Triassic coals in the Leping area, Jiangxi Province, southeast China

Abstract Permian and Triassic coals from a series of mines in Jiangxi Province, China, exhibit a number of unusual geochemical, mineralogical, and petrographic characteristics. The high volatile bituminous Permian coals have high concentrations of the suberinite-like maceral “barkinite.” The origin, and even the distinct character, of “barkinite” are in dispute and, consequently, it has not been recognized as a distinct maceral by the International Committee for Coal and Organic Petrology (ICCP). The Permian bituminous coals have relatively high concentrations of pyrite and marcasite. Otherwise, detrital minerals dominate their geochemistry. The Triassic coals, all from one mine complex, have higher rank (a Permian coal is also mined). Most samples straddle the low volatile bituminous/semi-anthracite boundary. The one semi-anthracite-rank Permian coal shows signs of incipient coking. A Triassic coal in the same fault block is coked by an igneous intrusions found in the mine. The coals have, in general, been dolomitized. Aside from the geochemical imprint of the dolomitization, trace element associations suggesting a contribution from a detrital mineral assemblage dominate the coals.

Speciation and sources of atmospheric aerosols in a highly industrialised emerging mega-city in Central China

Monitoring air quality in large urban agglomerations is the key to the prevention of air pollution-related problems in emerging mega-cities. The city of Wuhan is a highly industrialised city with >9 million inhabitants in Central China. Simultaneous PM10 sampling was performed during 1 year at one urban and one industrial site. Mean PM10 daily levels (156 microg m(-3) at the urban site and 197 microg m(-3) at the industrial hotspot) exceed the US-EPA or EU annual limit values by 3-4 times. A detailed study of daily speciation showed that the mean chemical composition of PM10 presents minimal differences between peak and low PM episodes. This implies that PM10 aerosols in the study area result from local emissions, and air quality management and abatement strategies in Wuhan should thus focus on local anthropogenic sources. The levels of some elements of environmental concern are relatively high (409-615 ngPb m(-3), 66-70 ngAs m(-3), 116-227 ngMn m(-3), 10-12 ngCd m(-3)) due to industrial, but also urban emissions. Principal component analysis identified a mineral source (probably cement and steel manufacture) and smelting as the main contributors to PM10 levels at the industrial site (34%), followed by a coal fired power plant (20%) and the anthropogenic regional background (16%). At the urban site the major PM10 source is a mixed coal combustion source (31%), followed by the anthropogenic regional background (28%) and traffic (16%).

Geological controls on the quality of coals from the West Shandong mining district, Eastern China

Abstract The basic coal quality parameters, coal petrology, mineralogy and geochemistry were investigated for coal seams 2, 3 and 4 (Permian Shanxi Formation) and 11, 12, 13 and 15 (Carboniferous Taiyuan Formation) of the Xinwen and Feicheng coal fields in the West Shandong mining district, East China. Rank parameters indicate a high volatile C to B bituminous rank for the Shandong coal. Coal from the Zhaizhen and Cha Zhuang mines is characterised by high vitrinite and low–middle inertinite and liptinite contents. Inertinite contents show an increase towards the top of the stratigraphic sequence from coal seams 15, 13 and 11 to coal seams 4 and 2. This trend may be related to a stratigraphic trend characterised by the evolution of relatively more reducing conditions of the synsedimentary coal forming environment in the early Taiyuan coals (marine-influenced lower delta plain) to more oxidising paleoenvironments of the Upper Shanxi coal seams (upper delta plain). Major mineral phases present in the Shandong coal are quartz, kaolinite, pyrite and calcite. Traces of other primary minerals (dolomite, ankerite, illite, opal, feldspars and marcasite) and weathering products (gypsum, melanterite and hematite) can be found in several coal seams. The Lower Permian coal seams (two to four) have a lower mineral content (8–14% ash db) than the Upper Carboniferous coal seams (15–37% ash db), owing to the lower proportions of quartz and sulphide mineral. The occurrence and distribution of the different minerals in the Shandong coal indicates a paragenetic sequence characterised by an early syngenetic stage (detrital minerals, framboidal, euhedral and massive cell-filling pyrite, ankerite, neomorphic quartz and kaolinite), middle and late syngenetic stages (radial and fibrous marcasite aggregates, massive pyrite) and an epigenetic stage (carbonates and sulphides as cleat filling). A clear differentiation exists between the Shanxi and the Taiyuan coal seams, based on the higher sulphide contents of the Taiyuan coal (3.3 to 6.2% S db) compared with the Shanxi coal (0.4 to 0.8% S db). This differentiation is related to marine influence on the depositional environment of coal seams 11 to 15, which has been reported by earlier studies. Vertical variations of the abundance of major and trace elements are discussed on the basis of this differentiation. An epigenetic external enrichment of Ge, Mo and U at the top of most of the coal seams is observed, and major and trace element affinities are deduced for the West Shandong coal.

Determination of elemental affinities by density fractionation of bulk coal samples from the Chongqing coal district, Southwestern China

Abstract The occurrence and distribution of major and trace elements have been investigated in two coal-bearing units in the Chonqing mining district (South China): the Late Permian and Late Triassic coals. The Late Permian coals have higher S contents than the Late Triassic coals due to the fixation of pyrite in marine-influenced coal-forming environments. The occurrence of pyrite accounts for the association of a large number of elements (Fe, S, As, Cd, Co, Cu, Mn, Mo, Ni, Pb, Sb, Se, and Zn) with sulphides, as deduced from the analysis of the density fractions. The marine influence is probably also responsible for the organic association of B. The REEs, Zr, Nb, and Hf, are enriched by a factor of 2–3 with respect to the highest levels fixed for the usual worldwide concentration ranges in coal for these elements. The content of these elements in the Late Permian coal is higher by a factor of 5–10 with respect to the Late Triassic coal. Furthermore, other elements, such as Cu, P, Th, U, V, and Y, are relatively enriched with respect to the common range values, with maximum values higher than the usual range or close to the maximum levels in coal. The content of these elements in the Late Permian coal is higher than the Late Triassic coal. These geochemical enrichments are the consequence of the occurrence, in relatively high levels, of phosphate minerals, such as apatite, xenotime, and monazite, as deduced from the study of the density fractions obtained from the bulk coal. The Late Triassic coal has a low sulphur content with a major organic affinity. The trace element contents are low when compared with worldwide ranges for coal. In this coal, the trace element distribution is governed by clay minerals, carbonate minerals, and to a lesser extent, by organic matter and sulphide minerals. Major differences found between late Permian and Triassic coals are probably related to the source rocks, given that the main source rock of the late Permian epicontinental marine basin is the Emeishan basalt formation, characterised by a high phosphate content.

Synthesis of merlinoite from Chinese coal fly ashes and its potential utilization as slow release K-fertilizer

This study focuses on the synthesis of merlinoite from Chinese coal fly ashes by KOH direct conversion method, with special emphasis on the application of synthetic merlinoite as fertilizer. These fly ashes were collected from two pulverized-coal combustion (PCC) power plants in Xinjiang, Northwest China. The synthesis results are influenced by fly ash characteristics and different synthesis conditions (KOH solution concentrations, activation temperature, time, and KOH/fly ash ratios). A high quality merlinoite-rich product was synthesized under optimal activation conditions (KOH concentration of 5M, activation temperature of 150°C, activation time of 8h and KOH/fly ash ratio of 2l/kg), with a cation exchange capacity (CEC) of 160cmolkg(-1). The synthetic merlinoite is proved to be an efficient slow release K-fertilizer for plant growth, indicating that it can be widely used for high-nutrient demanding crops growing in nutrient-limited soils and for large-area poor soil amendment in opencast coal mine areas around the power plants that will substantially grow with the increasing coal combustion in Xinjiang in the near future.

Mineralogical and geochemical composition of Middle Permian Lucaogou Formation in the southern Junggar Basin, China: implications for paleoenvironment, provenance, and tectonic setting

The mineralogy and geochemistry of the Middle Permian Lucaogou shale provide information regarding tectonic setting, depositional environment, sedimentary provenance, and chemical properties. The Lucaogou shale consists predominately of quartz and clay minerals with subsidiary feldspar. The mineralogical composition is enriched in SiO2, P2O5, CaO, and Na2O relative to post-Archean Australian shales (PAAS). The abundant free SiO2 and elevated CaO relative to PAAS have led to depletions of most of trace elements due to dilution effects. The chemical index of alteration (CIA) indicates that sediment-source region has undergone low to moderate chemical weathering. The index of compositional variability (ICV) suggests that the shales have low compositional maturity and are most likely dominated by first-cycle deposits. The dominance of plagioclase over K-feldspar in amounts and extrapolation of the analyzed shales back to the plagioclase-alkali feldspar line in the A-CN-K diagram indicate that the shales could have been derived from plagioclase-rich source rocks. The Al2O3/TiO2 ratio and chondrite-normalized rare earth element (REE) patterns display a derivation from felsic rocks. Tectonic setting discriminant diagrams and the chondrite-normalized REE patterns infer a continental island arc setting for sediment-source region. The redox-sensitive elemental ratios and paleosalinity indices reflect an anoxic mildly brackish-influenced to brackish-influenced paleoenvironment.

A review on the applications of coal combustion products in China

ABSTRACT Owing to the continuous high demand for energy, huge amounts of coals are consumed every year in China, giving rise to large volumes of coal combustion products (CCPs) from coal-fired power plants. Fly ash (FA), bottom ash (BA), boiler slag (BS), and flue gas desulphurization (FGD) gypsum are the primary CCPs generated. The disposal of these CCPs may occupy large areas of useful cultivated land, and cause serious environmental problems. However, these products might be also utilized as recoverable resources. Therefore, it is of economic and environmental significance to carry out research on the utilization of these CCPs. The present review first describes the physicochemical, mineralogical, and environmental geochemical properties of FA, slag, and FGD gypsum. Then the authors focus on the current and potential high value-added applications for these products in China. The utilization of FA for concrete and cement, soil amendment and fertilizer, in the ceramic industry, for catalysis, as adsorbents for the removal of flue gas, heavy metals, dyes and organic compounds, for zeolite and geopolymer synthesis, for recovery of valuable metals, and for recovery of unburned carbon and cenospheres, is discussed. The utilization of slag, such as reclamation of the burnable carbon, use in concrete, cement, and building materials, for roadway pavement and waste-water treatment, and for the production of acoustic barriers is reviewed as well. The current utilization of FGD gypsum includes use as a cement retarder, for the production of building plaster (β-hemihydrated gypsum) and calcium sulphate whiskers (α-hemihydrated gypsum), the production of fire-resistant panels, and use as a fertilizer and soil amendment agent. Furthermore, the possible influence of CCP properties on their utilization, and the advantages and disadvantages of various applications are discussed in this review. Finally, new directions for the future utilization prospects of CCPs in China are proposed.