Study on the characteristics of mineral matter in Huainan coals by computer controlled scanning electron microscope (CCSEM)

The mineral features, ash composition, ash fusion temperature of Huainan coals were investigated by CCSEM, X-ray fluorescence (XRF) and JIS (Japan Industrial Standard) ash cone melting method respectively. The mineral matter is characterized by higher aluminosilicate clay minerals contents (more than 60% of the total mineral matter in coal) with quartz, which accounts for the higher ash flow temperatures, frequently higher than1 500℃. The contents of calcite and dolomite in Huainan coals range from 0.16% to about 11.57%. Another important non-silicate mineral matter, pyrite, ranges from 0.73% to 12.25%. Low amount of kaolinite-type clays and high amount of calcite and pyrite in the HN115 and XM coals are beneficial to ash melting. It is suggested that the high content of kaolinite in Huainan coals shows the high ash fusion temperature. CCSEM results also provide the size distribution of the minerals in Huainan coals. Generally, the mineral has bimodal size distribution in 6 Huainan coals.

Investigation of Organic Matter Extraction from Moroccan Oil Shale

This study focuses on investigating the effect of various solvents on the supercritical extraction of organic matter from Moroccan oil shales, with the goal of determining the optimal operating conditions that result in a high yield of high-quality oil rich in aromatic compounds. The results of this study demonstrate that the extraction yield and quality of the extracted oil heavily depend on the chosen operating conditions for supercritical or subcritical extraction of organic matter from oil shale. Additionally, the study found that phenol can effectively degrade oil shale and enable extraction of nearly all the organic matter, even under mild conditions (T = 390˚C, P = 1.2 MPa, Time = 2.5 h. Furthermore, the oils obtained through this extraction process are of high quality, with a rich content of maltenes, and a higher concentration of aromatic compounds and lower levels of sulfur than those obtained using other solvents.

Investigation of Organic Matter Extraction from Moroccan Oil Shale

This study focuses on investigating the effect of various solvents on the supercritical extraction of organic matter from Moroccan oil shales, with the goal of determining the optimal operating conditions that result in a high yield of high-quality oil rich in aromatic compounds. The results of this study demonstrate that the extraction yield and quality of the extracted oil heavily depend on the chosen operating conditions for supercritical or subcritical extraction of organic matter from oil shale. Additionally, the study found that phenol can effectively degrade oil shale and enable extraction of nearly all the organic matter, even under mild conditions (T = 390˚C, P = 1.2 MPa, Time = 2.5 h. Furthermore, the oils obtained through this extraction process are of high quality, with a rich content of maltenes, and a higher concentration of aromatic compounds and lower levels of sulfur than those obtained using other solvents.

Influence of coal blending on mineral transformation at high temperatures

Transformation of mineral matter is important for coal utilization at high temperatures.This is especially true for blended coal.XRD and FTIR were employed together to study the transformation of mineral matter at high temperature in blended coals.It was found that the concentration of catalytic minerals, namely iron oxides, increases with an increasing ratio of Shenfu coal, which could improve coal gasification.The transformation characteristics of the minerals in blended coals are not exactly predictable from the blend ratio.This was proved by comparing the iron oxide content to the blending ratio.The results from FTIR are comparable with those from XRD.FTIR is an effective method for examining variation in mineral matter.

Demineralization mechanism and influence of parameters on high ash Indian coal by chemical leaching of acid and alkali solution

The current research was investigated the mechanism of coal demineralization and the effect of leaching parameters on high ash coal and study the characterization of pre and post-treated coal. The two high ash Indian coal selected from Mahanadi Coalfield Limited, Odisha, pulverized to 375, 230 and 180 gm particle size were undergone simultaneous acid and alkali treatment at a different concentration, temperature and time. The percent demineralization was increased with decrease the size of the particle and rises with leaching parameters. The investigation suggested 180 μm particle size offers efficient demineralization for both coals at 30% NaOH and 30% H2SO4 concentration. The alkali leaching leads to obtaining the demineralization 46% and 42% whereas acid treatment resulted in 34% and 32% of the original coal samples. The extent of demineralization was improved the calorific value of coal. Besides, the degree of demineralization was proved from the FTIR, XRF and FESEM-EDX analysis results. FTIR analysis result showed that the peak intensity of mineral band decreased by the leaching effect and the degree of demineralization was significantly obtained to large extent by the X-ray Fluorescence spectrometer; which elucidates major minerals removed from coal by the leaching effect of acid and alkali solution.

Geochemical Characterization and Mineralogy of Babouri-Figuil Oil Shale,North-Cameroon

Organic geochemistry methods such as high temperature combustion, Rock-Eval pyrolysis and gas analysis were used to analyze oil shale from Babouri-Figuil Basin. Results show that the average content of organic matter is 36.25 %wt, while that of mineral matter is 63.75 %wt. The total organic carbon (TOC) is between 15.93 %wt and 26.82 %wt. The HI vs. Tmax diagram indicates an immature Type I kerogen. The average value of the oil potential (S2b) is 149.95 mg HC/g rock. The gases obtained by retort process are H2, CO2, CO and CnH2n, CnH2n+2. Finally, it emerges that, the organic matter of Babouri-Figuil shales was immature or has just reached the beginning of the oil window. The mineralogical study of Babouri-Figuil oil shale has been carried out by means of XRD (X-Ray Diffractometry) and XRF (X-Ray Fluorescence spectrometry). The results show that mineral matrix contains silica, carbonates, sulphates, oxides and clay minerals. Besides, compounds contain metals and metalloids like Fe, In, Ca. The main oxides are SiO2 (majority), CaO, Fe2O3, Al2O3, SO3, and K2O.

Formation,evolution,reconstruction of black shales and their influence on shale oil and gas resource

Black shales are important products of material cycling and energy exchange among the lithosphere,atmosphere,hydrosphere,and biosphere.They are widely distributed throughout geological history and provide essential energy and mineral resources for the development of human society.They also record the evolution process of the earth and improve the understanding of the earth.This review focuses on the diagenesis and formation mechanisms of black shales sedimentation,composition,evolution,and reconstruction,which have had a significant impact on the formation and enrichment of shale oil and gas.In terms of sedimentary environment,black shales can be classified into three types:Marine,terrestrial,and marine-terrestrial transitional facies.The formation processes include mechanisms such as eolian input,hypopycnal flow,gravity-driven and offshore bottom currents.From a geological perspective,the formation of black shales is often closely related to global or regional major geological events.The enrichment of organic matter is generally the result of the interaction and coupling of several factors such as primary productivity,water redox condition,and sedimentation rate.In terms of evolution,black shales have undergone diagenetic evolution of inorganic minerals,thermal evolution of organic matter and hydrocarbon generation,interactions between organic matter and inorganic minerals,and pore evolution.In terms of reconstruction,the effects of fold deformation,uplift and erosion,and fracturing have changed the stress state of black shale reservoirs,thereby having a significant impact on the pore structure.Fluid activity promotes the formation of veins,and have changed the material composition,stress structure,and reservoir properties of black shales.Regarding resource effects,the deposition of black shales is fundamental for shale oil and gas resources,the evolution of black shales promotes the shale oil and gas formation and storage,and the reconstruction of black shales would have caused the heterogeneous distribution of oil and gas in shales.Exploring the formation mechanisms and interactions of black shales at different scales is a key to in-depth research on shale formation and evolution,as well as the key to revealing the mechanism controlling shale oil and gas accumulation.The present records can reveal how these processes worked in geological history,and improve our understanding of the coupling mechanisms among regional geological events,black shales evolution,and shale oil and gas formation and enrichment.

Preservation of organic matter in soils of a climobiosequence in the Main Range of Peninsular Malaysia

Limited information is available about factors of soil organic carbon(SOC) preservation in soils along a climo-biosequence. The objective of this study was to evaluate the role of soil texture and mineralogy on preservation of SOC in the topsoil and subsoil along a climo-biosequence in the Main Range of Peninsular Malaysia. Soil samples from the A and B-horizons of four representative soil profiles were subjected to particle-size fractionation and mineralogical analyses including X-ray diffraction and selective dissolution. The proportion of SOC in the 250-2000 μm fraction(SOC associated with coarse sand) decreased while the proportion of SOC in the <53 μm fraction(SOC associated with clay and silt)increased with depth. This reflected the importance of the fine mineral fractions of the soil matrix for SOC storage in the subsoil. Close relationships between the content of SOC in the <53 μm fraction and the content of poorly crystalline Fe oxides [oxalate-extractable Fe(Fe_o) – pyrophosphate-extractable Fe(Fe_p)] and poorly crystalline inorganic forms of Al [oxalateextractable Al(Al_o) – pyrophosphate-extractable Al(Al_p)] in the B-horizon indicated the importance of poorly crystalline Fe oxides and poorly crystalline aluminosilicates for the preservation of SOC in the Bhorizon. The increasing trend of Fe_o-Fe_p and Al_o-Al_p over elevation suggest that the importance of poorly crystalline Fe oxides and poorly crystalline aluminosilicates for the preservation of SOC in the Bhorizon increased with increasing elevation. This study demonstrates that regardless of differences in climate and vegetation along the studied climobiosequence, preservation of SOC in the subsoil depends on clay mineralogy.

Dissimilatory iron reduction contributes to anaerobic mineralization of sediment in a shallow transboundary lake

Dissimilatory iron reduction(DIR)coupled with carbon cycling is increasingly being recognized as an influential process in freshwater wetland soils and sediments.The role of DIR in organic matter(OM)mineralization,however,is still largely unknown in lake sediment environments.In this study,we clarified rates and pathways of OM mineralization in two shallow lakes with seasonal hydrological connectivity and different eutrophic situations.We found that in comparison with the domination of DIR(55%)for OM mineralization in Lake Xiaoxingkai,the contribution of methanogenesis was much higher(68%)in its connected lake(Lake Xingkai).The differences in rates and pathways of sediment OM mineralization between the two lakes were attributed to higher concentrations of carbonate associated iron oxides(Fecarb)in Lake Xiaoxingkai compared to Lake Xingkai(P=0.002),due to better deposition mixing,more contributions of terrigenous detrital materials,and higher OM content in Lake Xiaoxingkai.Results of structural equation modeling showed that Fecarb and total iron content(TFe)regulated 25%of DIR in Lake Xiaoxingkai and 76%in Lake Xingkai,accompanied by a negative effect of TFe on methanogenesis in Lake Xingkai.The relative abundance and diversity of Fe-reducing bacteria were significantly different between the two lakes,and showed a weak effect on sediment OM mineralization.Our findings emphasize the role of iron minerals and geochemical characterizations in regulating rates and pathways of OM mineralization,and deepen the understanding of carbon cycling in lake sediments.

Limited impacts of occasional tillage on dry aggregate size distribution and soil carbon and nitrogen fractions in semi-arid drylands

Tillage management that minimizes the frequency and intensity of soil disturbance can increase soil carbon(C)and nitrogen(N)sequestration and improve the resilience of dryland cropping systems,yet the impact of occasional disturbance on soil aggregate formation and the soil organic carbon(SOC)storage within aggregates has not been studied well.We evaluated the effect of four tillage management practices on soil dry aggregate size distribution,aggregate-protected C and N,mineral-associated organic matter carbon(MAOM-C),particulate organic matter carbon(POM-C),and corn(Zea mays L.)and sorghum(Sorghum bicolor(L.)Moench)yields in a semi-arid dryland cropping system.Treatments included conventional tillage(CT),strip-tillage(ST),no-tillage(NT),and occasional tillage(OT)management in a corn-sorghum rotation.Soil macro-aggregates were 51-54%greater under ST,NT,and OT,while small and micro-aggregates were greater in CT.Conventional tillage reduced soil aggregate-associated C by 28-31%in macro-aggregates and 47-53%in small aggregates at 26 months(M)sampling compared to ST,NT,and OT.In clay+silt fraction,CT had 14-16%,21-26%,and 36-43%less SOC at 7,14,and 26M samplings,respectively,than ST,NT,and OT.Aggregate associated N was generally similar under ST,NT,and OT,which was greater on average than CT.Soil MOAM-C and POM-C under ST,NT,and OT were generally greater than respective SOC fractions under CT at 19 and 26 M after OT implementation.Corn and sorghum yields were similar among tillage systems in 2020,but greater under ST,NT,and OT than CT in 2021.Our results suggest that while frequent intensive tillage can lower SOC and N storage,a single stubble mulch occasional tillage after several years of NT does not lead to soil C and N losses and soil structural instability in semi-arid drylands.

Crystallization and viscosity-temperature characteristics during co-gasification of industrial sludge and coal

Co-gasification of industrial sludge(IS)and coal was an effective approach to achieve harmless and sustainable utilization of IS.The long-term and stable operation of a co-gasification largely depends on fluidity of coal-ash slag.Herein,the effects of IS addition on the crystallization and viscosity of Shuangmazao(SMZ)coal were investigated by means of high temperature stage coupled with an optical microscope(HTSOM),a scanning electron microscopy coupled with an energy dispersive Xray spectrometry(SEM-EDS),X-ray diffraction(XRD),a Fourier transform infrared spectrometer(FTIR),and FactSage software.The results showed that when the proportion of IS was less than 60%,with the addition of IS,the slag existed in an amorphous form.This was due to the high content of SiO_(2) and Al_(2)O_(3) in SMZ ash and blended ash,which had a high glass-forming ability(GFA).The slag formed at a high temperature had a higher polymerization degree and viscosity,which led to a decrease in the migration ability between ions,and ultimately made the slag difficult to crystallize during the cooling.When the proportion of IS was higher than 60%,the addition of IS increased the CaO and FeO content in the system.As network modifiers,CaO and FeO could provide O^(2−)at a high temperature,which reacted with silicate network structure and continuously destroyed the complexity of network structure,thus reducing the polymerization degree and viscosity of slag.At this time,the migration ability between ions was enhanced,and needle-shaped/rod-shaped crystals were precipitated during the cooling process.Finally,the viscosity calculated by simulation and Einstein-Roscoe empirical formula demonstrated that the addition of IS could significantly improve the fluidity of coal ash and meet the requirements of the liquid slag-tapping gasifier.The purpose of this work was to provide theoretical support for slag flow mechanisms during the gasifier slagging-tapping process and the resource treatment of industrial solid waste.