Effect Of Mineral Matter Research Articles

Effect of mineral matter on product yield in supercritical water extraction of lignite at different temperatures

The effect of demineralization on conversion of Soma Lignite in supercritical water extraction was studied using a batch autoclave operated at 400, 450 and 500 °C under nitrogen atmosphere. The experiments were carried out to investigate the effect of mineral matter and temperature on gaseous, liquid, residue yield and composition of gaseous products. According to the results, main product in gaseous state is CO 2. Temperature is key factor affecting product distribution when compared the effect of minerals in lignite. As temperature was increased, yield of gas and solid residue increased, while yields of liquid decreased for raw and demineralized lignite samples. The removal of mineral matter caused to decrease the conversion for all lignite samples and to increase the carbon content of solid residue in supercritical water extraction.

Effects of Mineral Matter and Coal Blending on Gasification

Two Chinese coals were used for coal blending to study the effects of mineral matter and coal blending on gasification. The transformational behaviors of blending coals were studied with FactSage thermodynamic calculation. Most mineral matter was transformed into Ca aluminosilicates and mullite at high temperatures. High-temperature gasification was performed from 1100 to 1500 °C to examine the gasification behavior of blended chars. Considering the viscosity results of coal ash from blending coals, the melting ash was assumed to hinder the gasification reactions at high temperatures. The Fourier transform infrared (FTIR) spectrum indicated the existence of iron oxides, which was verified by FactSage, and iron oxides led to thermal carbon reactions that promoted the gasification reactions.

Gasification of waste biomass chars by carbon dioxide via thermogravimetry. Part I: Effect of mineral matter

A series of carbon dioxide gasification tests of waste biomass chars were performed in a thermogravimetric analysis system, at non-isothermal heating conditions. The effects of the inorganic constituents of the fuels on thermal conversion characteristics were examined. Reaction rates were determined by developing a power law model.The bulk of char gasification process occurred between 800 and 950°C. Maximum reaction rate and conversion were exhibited by waste paper char, due to its higher surface area.Inherent alkaline and alkaline earth carbonates and sulphates acted as catalysts, by increasing the reactivity of the fuels in carbon dioxide and causing their degradation to start at lower temperatures (60–75°C).The kinetic model fitted the experimental results accurately. Activation energy values and reaction order ranged from 180 to 370kJ/mol and 0.4 to 0.6, respectively, among the chars, indicating a chemically controlled process.

Effect of suspended mineral matter on production characteristics of bacterio- and phytoplankton

The effect was determined of organo-mineral detritus (OMD), one of the components of suspended mineral matter in aquatic ecosystems, on the production characteristics of bacterioplankton (bacterial production P b and destruction of organic matter R b, as well as bacterial growth efficiency BGE). The relation was determined between these parameters and the ratio of the content of suspended mineral matter M to the total organic carbon content (M/TOC). More active utilization of organic matter by bacterioplankton in the presence of OMD resulted in its positive effect on specific production characteristics of the phytoplankton.

Kinetic analysis of NO-Char reaction

Two Chinese coals were used to prepare chars in a flat flame flow reactor which can simulate the temperature and gas composition of a real pulverized coal combustion environment. Acid treatment on the YB and SH chars was applied to obtain demineralized chars. Kinetic characterization of NO-char reaction was performed by isothermal thermogravimetry in the temperature range of 973–1,573 K. Presence of catalytic metal matter can increase the reactivity of chars with NO, which indicates that the catalytic effects of inherent mineral matter play a significant role in the NO-char reaction. The discrete random pore model was applied to describe the NO-char reactions and obtain the intrinsic kinetics. The model can predict the data for all the chars at various temperatures well, but underestimate the reaction rates at high carbon conversions for the raw YB and SH chars, which can be attributed to the accumulation of metal catalyst on char surface.

EFFECT OF MINERAL MATTER ON PRODUCT YIELD AND COMPOSITION AT ISOTHERMAL PYROLYSIS OF TURKISH OIL SHALES

This study was aimed to investigate the effect of mineral matter of Goynuk oil shales (GOS) on pyrolysis and product evolution. Organic part was separated from mineral matter before pyrolysis in an isothermal pyrolysis reactor. In the demineralization step, carbonate, pyrite and silicates were removed from kerogen by using HCl, HNO 3 and HF, respectively. Thereafter all samples were pyrolized in an isothermal pyrolysis apparatus. The temperatures for pyrolysis experiments were 450, 500, 550, 600, 650 °C. Recoveries of volatiles and total hydrocarbons increased with increasing temperature. At pyrolysis of silicate-free oil shale (GOS-F), volatile hydrocarbon recovery (VHR) increased nearly by 10 wt.% as compared with VHR from raw oil shale sample (GOS-R) at each pyrolysis temperature. Carbon content of solid residue was also calculated. The effect of mineral content of oil shale on product yield and composition was determined by establishing carbon balance in the reactor. The amount of solid residue decreased as a function of demineralization degree. The pyrolysis reaction in the presence of silicate mineral showed the catalytic effect of silicate minerals aiding coking reactions, and carbon deposition decreased averagely by 20 wt.% in silicatefree oil shale compared with the value for GOS-R at each temperature.

Effect of mineral matter on the formation of NO X precursors during biomass pyrolysis

Formation of NO X precursors during pyrolysis of three typical kinds of biomass (wheat straw, rice straw and corn cob) was studied using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared (FTIR) spectrometer in argon atmosphere. Two pretreatment methods, including deionized water washing and acid washing were utilized to investigate the effect of included minerals on the distribution of nitrogen containing species during wheat straw pyrolysis. KOH and CaO were loaded onto the demineralized (dem) wheat straw to study the effect of excluded minerals on nitrogen release. The residues of the samples after pyrolysis were characterized by X-ray diffraction (XRD) analysis. The results show that different kinds of biomass have distinctive formation characteristics of N-containing species. HCN and HNCO are the main N-containing species for rice straw, while NH 3 and HCN are the main N-containing species for wheat straw and corn cob. The existence of minerals influences the formation of N-containing species during biomass pyrolysis. Both the included potassium and excluded potassium promote N-conversion to NH 3, HCN, NO and HNCO at lower temperature, but decrease the total yields of N-containing species. The included calcium decreases N-conversion to HCN, NH 3 and HNCO at lower temperature (<about 330 °C), while favors the total yields of N-containing species. However, the presence of added calcium restrains N-conversion to HCN, NH 3, NO and HNCO.

Effect of mineral matter on coal self-heating rate

Adiabatic self-heating tests have been conducted on subbituminous coal cores from the same seam profile, which cover a mineral matter content range of 11.2–71.1%. In all cases the heat release rate does not conform to an Arrhenius kinetic model, but can best be described by a third order polynomial. Assessment of the theoretical heat sink effect of the mineral matter in each of the tests reveals that the coal is less reactive than predicted using a simple energy conservation equation. There is an additional effect of the mineral matter in these cases that cannot be explained by heat sink alone. The disseminated mineral matter in the coal is therefore inhibiting the oxidation reaction due to physicochemical effects.

Role of activated carbon structural properties and surface chemistry in mercury adsorption

In this work the performance of activated carbons prepared from raw and demineralised lignite for gas-phase Hg° removal was evaluated. A two-stage activation procedure was used for the production of the activated samples. In order to study the effect of mineral matter on pore structure development and surface functionality of the activated carbons, a demineralisation procedure involving a three-stage acid treatment of coals, was used, prior to activation. Hg° adsorption tests were realized in laboratory-scale unit consisted of a fixed-bed reactor charged with the tested activated samples. The examined adsorbent properties that may affect removal capacity were the pore structure, the surface chemistry and the presence of sulphur on the surface of activated carbons. The obtained results revealed that activated carbons produced from demineralised lignite posses a high-developed micropore structure with increased total pore volume and BET surface area. These samples exhibit enhanced Hg° adsorptive capacity. In all cases, mercury removal efficiency increased by sulphur addition. Finally, the starting material properties and activation conditions affect the concentration and the type of the oxygen groups on activated carbon surface, that have been determined with TPD-MS experiments.

Effect of Mineral Matter on NO Reduction in Coal Reburning Process

The effect of mineral matter on the NO reduction efficiency during the coal reburning process was studied in an entrained flow reactor. Apart from the homogeneous reactions between hydrocarbon radicals and NO, the heterogeneous reaction between NO and char is also important in the coal reburning process. The discrepancy in NO reduction between two kinds of bituminous coals with similar volatile matter and inherent nitrogen contents was investigated. Shenhua coal enriched with Na, K, Ca, and Fe in ash has more than a 15% predominance over the Huainan coal. The mineral matters in the coal ash were studied by the demineralization and reimpregnation process. The original coal, demineralized coal, and impregnated coal were evaluated as reburning fuels. Results show that the mineral matter in the coal has great influence on the NO reduction efficiency during the coal reburning process. The additional mineral matter can greatly improve the NO reduction efficiency of the coal reburning process. The effective sequ...

The effect of mineral matter on the physical and chemical activation of low rank coal and biomass materials

Abstract The effect of inorganic constituents on the thermal behaviour of low rank coals, as well as agricultural and forestry by-products, during pyrolysis and combustion processes was investigated. Selective demineralization of each fuel with acids was used. Raw and demineralized samples were analyzed for ash content and composition (mineralogical and chemical), surface area and porosity, as well as thermal conversion characteristics in inert and air atmospheres. Reactivity and kinetic experiments were performed by non-isothermal thermogravimetry, over the temperature range of 25–850 °C, at a heating rate of 10 °C/min and with a material particle size of −250 μm. The extent of mineral matter removal from the materials studied, ash composition and structural characteristics depended upon the type of the fuel and the method of acid treatment. Generally, calcium, magnesium, potassium and silicon minerals acted as inert materials, inhibiting the pyrolysis and combustion rates of the samples. However, they increased the sensitivity of the reactions, by lowering the peak temperatures. A first-order parallel reactions model for pyrolysis and a power low model for combustion fitted the experimental results accurately. Mineral matter had a small influence on the kinetic parameters of biomass samples, but appeared to hinder the overall process in the case of the coals.

Pyrolysis and combustion behaviour of coal–MBM blends

In the present work, thermogravimetric analysis was employed in order to investigate the behaviour of MBM and their blends with Greek brown coal, under pyrolysis and combustion conditions. MBM presented enhanced pyrolysis rates reflecting its high volatile and low ash contents compared to Greek brown coal. Increased conversion rates were observed when MBM was added in the brown coal sample. Significant interactions were detected between the two fuel blend components leading to significant deviations from the expected behaviour. The catalytic effect of mineral matter on the pyrolysis of MBM resulted in reaction rate decrease and DTG curve shift to lower temperatures for the demineralised MBM. Alterations in the combustion process due to the mineral matter were minimal when testing the blends. Interactions maintained during combustion and lower reactivity of MBM was achieved due to the reduced oxygen content.

Studies on the combustion behaviour of blends of Indian coals by TGA and Drop Tube Furnace

Combustion behaviour of blends of two Indian coals of same rank with wide variation in mineral matter content were studied using Thermogravimetric Analyzer (TGA) and Drop Tube Furnace (DTF). The characteristic TGA parameters determined from the burning profiles showed both additive and non-additive behaviour. The burnout temperature and peak temperature showed a linearly decreasing trend with the increasing proportion of the high ash coal. Deviation from the linear trend was observed in the case of the reactivity parameter. The high ash coal showed better TGA reactivity than the low ash coal. The higher TGA reactivity could arise from the combined effect of mineral matter and the nature and distribution of the macerals, particularly those of the inertinite group. The burnout in DTF showed a nonlinear effect. The burnout behaviour of the coals and their blend observed in DTF was not similar to that reflected in TGA. Coal blends with less than 50% of high ash coal showed better burnout than the individual coals.

Removal of pollutants from poor quality coals by pyrolysis

Combustion of poor quality coals and wastes is used today worldwide for energy production. However, this entails significant environmental risks due to the presence of polluting compounds in them, i. e. S, N, Hg, and Cl. In the complex environment of combustion these substances are forming conventional (i. e. SOx, NOx) and toxic (PCDD/Fs) pollutants, while, the highly toxic Hg is volatilized in the gas phase mainly as elemental mercury. Aiming to meet the recently adopted strict environmental standards, and the need of affordable in cost clean power production, a preventive fuels pre-treatment technique, based on low temperature carbonization, has been tested. Clean coals were produced from two poor quality Greek coals (Ptolemais and Megalopolis) and an Australian coal sample, in a lab-scale fixed bed reactor under helium atmosphere and ambient pressure. The effect of carbonization temperature (200-900 ?C) and residence time (5-120 minutes) on the properties of the chars, obtained after pyrolysis, was investigated. Special attention was paid to the removal of pollutants such as S, N, Hg, and Cl. To account for possible mineral matter effects, mainly on sulphur removal, tests were also performed with demineralized coal. Reactivity variation of produced clean coals was evaluated by performing non-isothermal combustion tests in a TA Q600 thermo gravimetric analyzer. Results showed that the low temperature carbonization technique might contribute to clean coal production by effectively removing the major part of the existing polluting compounds contained in coal. Therefore, depending on coal type, nitrogen, mercury, and chlorine abatement continuously increases with temperature, while sulphur removal seems to reach a plateau above 500-600 ?C. More-over, the prolongation of carbonization time above 20 minutes does not affect the elemental conversion of the pollutants and carbonization at 500-600 ?C for ~20 minutes may be considered sufficient for clean coal production from poor quality coals. Clean coal production at higher pyrolysis temperatures results in observed higher initial combustion temperature, mainly due to lower volatile content in produced chars.

Comparison of the R70 self-heating rate of New Zealand and Australian coals to Suggate rank parameter

Samples from New Zealand and Australia have been tested in an adiabatic oven to assess the effect of rank on the R 70 self-heating rate of coal. A non-linear relationship can be defined for coals from both countries using the revised Suggate rank ( S r) parameter. Subbituminous coals have the highest R 70 self-heating rate values, which are 20 times that of high volatile A bituminous coals on a dry mineral matter free basis (∼ 1 cf. 20 °C h − 1). However, the moderating effects of moisture and mineral matter can reduce this difference to only 2–3 times for coal in-situ.

Effect of mineral matter and phenol in supercritical extraction of oil shale with toluene

Tarfaya oil shale was subjected to supercritical toluene extraction. The experimental results obtained show clearly that the mineral matter and phenol have a significant effect on the yield and the composition of the obtained oil.

Effect of inorganic matter on reactivity and kinetics of coal pyrolysis

Two Chinese coals, Shenfu subbituminous coal and Huolingele lignite, were used to investigate the effect of mineral matter in coal on reactivity and kinetic characteristics of coal pyrolysis. The experiments were carried out by using thermogravimetry to check the pyrolysis behavior of raw coal, HCl/HF demineralized coal and demineralized coal with inorganic matter (CaO, K 2CO 3 and Al 2O 3) added, respectively. The results showed that inherent mineral in coal had no evident effect on the reactivity and kinetics of coal pyrolysis. CaO, K 2CO 3 and Al 2O 3 all had a catalytic effect on the reactivity of coal pyrolysis, their effects were closely related to temperature region and coal types. The pyrolysis process of all the samples studied can be described by three independent first order kinetic model. Addition of inorganic matter the activation energy decreased and the characteristic temperature of coal changed.

Controls on Methane Adsorption Capacity of Lower Cretaceous Coals from Northeastern British Columbia, Canada: Part 2—Effect of Temperature, Pressure, Maceral Composition, and Mineral Matter on Adsorption

The effect of temperature, pressure, maceral composition, and mineral matter on the methane adsorption of coals from the Gething Formation was examined. Data was compared with coals from the Gates Formation in the same area and with coals from Australia. Adsorption capacity in the Gething coals appears to be moderately to strongly affected by the vitrinite (and pseudovitrinite) content and mineral matter, which does not only have a diluting effect, but also acts negatively on gas adsorptive capacity. Another explanation for the high gas adsorption capacity in the Gething coals may be related to the presence of free gas, which is more common when coals are below equilibrium moisture in a gas-saturated stratigraphy. Both Gething and Gates coals show an increase in gas-holding capacity, with increasing pressure as a function of vitrinite/inertinite ratio. Such an increase is absent in coals from the Bulli Seam, Sydney Basin, Australia.

The influence of mineral matters in coal on NO-char reaction in the presence of SO 2

The effect of mineral matter in char on NO-char reaction in the presence of SO 2 was studied by temperature programmed reaction and isothermal experiments. Three coals with different ranks and their demineralized samples were pyrolyzed in N 2 at 900 °C to prepare the chars. Different kinds of metals were loaded on the demineralized chars to compare their catalytic effect on NO conversion during NO-char reaction. The results show that the effect of mineral matter is closely related to the content of catalytically active components. More catalytically active components in mineral matter in the char, higher catalytic activity for NO-char reaction. While the inert components, such as Al 2O 3 and Si 2O 3, will abate the NO conversion. Besides the catalytic effect of active mineral matter, the reactivity of the char is another important factor to affect the NO conversion during NO-char reaction. With increasing coal rank, the resultant char shows lower activity for reduction of NO. The effect of SO 2 on the NO-char reaction is changed with temperature. At higher temperatures NO conversion is further enhanced by the reaction of NO–SO 2 and the increase in the amount of active sites due to the release of SO 2 chemisorbed on the char surface.

Evaluation of Combustion Characteristics of Chinese High-Ash Coals

The combustion characteristics of four Chinese high-ash coals were evaluated by thermogravimetric and surface analysis. Changes in surface area and porosity during combustion were investigated with original (as-received) coals, coal samples before ignition, and chars after burnout. To understand the roles of various ash components, comparative experiments were carried out with as-received, de-ashed, and impregnated coals. SiO2, Al2O3, CaCO3, MgO, Na2CO3, TiO2, K2CO3, Fe2O3, FeS2, FeSO4(NH4)SO4·6H2O, and NH4Fe(SO4)2·12H2O at different concentrations were used as chemical additives impregnated into the de-ashed coals to investigate their influence on coal combustion. Most of these minerals inhibited coal ignitability; only K and Ca were found to promote coal ignition. Fe, Al, Na, and Ca were found to hinder both ignition and burnout of coal. Other ash components demonstrated variable effects on coal ignition and burnout with changing concentrations and species. A full understanding of the different effects of mineral matter is essential to achieve improved performance with high-ash coal applications.