Non-coking Coal Research Articles

Characteristics and potential of coal for coking coal in Meliat Formation, Tarakan Basin, Nunukan, North Kalimantan, Indonesia

Abstract Coking coal is coal that melts, expands, then reconsolidates during carbonization and can produce coke as an iron refining agent in blast furnaces. Characterization of the potential of coking coal in Indonesia is still being developed. The research was conducted to find out how the potential of coal in the Meliat Formation for coking coal. The purpose of this study was to determine the characteristics and potential of coking coal from coal has been mined at PT. Duta Tambang Rekayasa and it was included in that formation. The samples analyzed were 4 units and the sample was a blend of coal has been mined at seams E, F, and G. The result, all coal has high ash (> 10% adb), volatile matter (> 31% dmmf), sulphur (> 1% daf), H/C (0.88 - 1)(%daf), O/C (0.11 - 0.19)(%daf) and a low vitrinite reflectance (Rmax < 0.5), which indicates that the coal parameter does not match the requirements for coking coal. the low CSN test values (1 - 1.5) and GKCT (B and C type) are the keys to coal in this research including non-coking coal. This coal will produce poor quality coke because many substances will evaporate and do not have plastic properties.

Comparative study on reduction behaviors of low- and high-grade fired hematite iron ore pellets in coal

The reduction behaviors of fired Ramallakota (low-grade) and Bolani (high-grade) iron ore pellets were studied isothermally at temperatures of 1123, 1173 and 1223 K in non-coking coal. The degree of reduction progressed with the rise in reduction temperature and time. Ramallakota iron ore pellets exhibited relatively higher reduction rates than Bolani iron ore pellets reduced under identical conditions due to their higher porosity and gangue contents. Comparison of XRD patterns confirmed almost complete reduction in Ramallakota iron ore pellets at all the studied reduction temperatures in a much shorter period. Fayalite and hercynite formations were observed in both the types of reduced iron ore pellets with higher intensities in the pellets of Ramallakota iron ore. SEM images revealed relatively more growth of iron whiskers in reduced Bolani high-grade iron ore pellets. The apparent activation energy values for the reduction of studied iron ore pellets by coal were calculated to be in the range 14–20 kJmol−1, while pellets reduced in coal char under identical conditions exhibited relatively higher values owing to their slower reduction rates.

Utilizing a sustainable surfactant from Cucurbita pepo seeds for eco-friendly flotation of non-coking coal in sustainable energy applications

Utilizing a sustainable surfactant from Cucurbita pepo seeds for eco-friendly flotation of non-coking coal in sustainable energy applications

Three-Dimensional Evaluation of Internal Structure of Coke Made by Blending Non-coking Coal Using X-ray Computed Tomography

Three-Dimensional Evaluation of Internal Structure of Coke Made by Blending Non-coking Coal Using X-ray Computed Tomography

Influence of feed mineralogical characteristics on the reduction behavior of low-grade iron ores

Reduction roasting followed by magnetic separation has become a major beneficiation technique to utilize low and lean-grade iron ore resources. However, the fundamentals of the reduction nature of iron ore are complex and largely depend upon the mineralogical characteristics of the raw material. In order to ascertain the complexities involving the phase transformation and reducibility nature of iron ores, experiments were conducted on four mineralogically different iron ores such as crushed fines, slime, BHQ and BHJ samples to examine their responses in terms of recovery and their enrichment in Fe content. The representative samples of each class were undergone through identical experimental conditions (850 °C temperature, 30 min resident time, 10% non-coking coal used as reductant) and it was observed that the crushed fines and slime showed the highest degree of reducibility while the BHQ and BHJ samples responded moderately to the process. Mineralogical characterization of both BHQ and BHJ show the presence of hematite mineral phases in the non-magnetic fractions, indicating the necessity of higher reductant content as well as residence time than the crushed fines and slimes. In essence, the banded ores require a higher temperature and reducing environment than the hematite and goethite-rich feed materials for higher magnetite conversion. In addition, the advantages of reduction roasting followed by magnetic separation process over direct magnetic separation process is highlighted in detail.

Effect of secondary gas-phase reactions (SGR) in pyrolysis of carbon feedstocks for anisotropic carbon materials production – 3: Modifying non-coking coal tar through co-pyrolysis of coal with linear low-density polyethylene and high-impact polystyrene

This work focuses on co-pyrolysis experiments of Utah Sufco coal with linear low-density polyethylene (LLDPE) and high-impact polystyrene (HIPS). These two plastic types have differing pyrolysis chemistries and have different hydrogen transfer behavior. Similar to earlier work in this series of papers, controlled secondary gas-phase reactions during pyrolysis were used to induce cracking and condensation reactions among the pyrolytic tar species. Co-pyrolysis tests were performed with feed plastic percentages ranging from 10 to 20 wt % and pyrolysis SGR temperatures ranging from 800 to 900° C. Analyses of the intermediate tar products showed that oxygen contents and aromaticity were substantially different, depending on the plastic, and resulting pitch softening points and mesophase contents also varied greatly depending on the starting plastic feedstock used. Most of the synergies observed in the co-pyrolysis results were negative, except for the oxygen content. Oxygen contents were higher than expected when LLDPE was used, resulting in reactive pitches with softening points >350° C. On the other hand, oxygen contents were lower than expected when HIPS was used, resulting in less reactive pitches. Ultimately, only the HIPS/coal samples created at the SGR temperature of 900° C had reasonable softening points at or under 350° C, making them the only samples created in this work potentially suitable for mesophase pitch-based carbon fiber production. The success in creating fusible mesophase pitches from co-pyrolyzing HIPS with Utah Sufco coal is likely attributed to the fact that polystyrene is a stronger hydrogen acceptor rather than donor, which should facilitate more cracking rather than stabilizing tar oxygen functional groups, making the tar species ultimately less reactive during thermal conversion to mesophase pitch.

Analysis of self-reducing composites with different iron ore-carbon ratio

The use of self-reducing agglomerates with ferrous burden is considered a sustainable alternative for blast furnace reducing fuel consumption and increasing productivity of the equipment. In this work, self-reducing mixtures composed by different ratios of iron ore and carbon sources were evaluated concerning their reduction performance and the phases quantification. Non-coking coal (NCC) and petroleum coke (PC) were used as iron ore reducing agents and in different C:O molar ratio. Firstly, the reactivity to CO2 of each reductant was evaluated and then, thermogravimetric tests were carried out with the self-reducing mixtures in a non-isothermal regime and argon atmosphere up to 1300 °C. The phase contents were identified by X-ray diffractometry (XRD) and quantified via image analysis under an optical microscope. The thermogravimetric tests evidenced that the C:O molar ratio equal to 0.75, which is equivalent to 20% in mass of NCC and 15% in mass of PC in the mixture, achieved the highest reacted fraction. At lower reducing agent ratios, the greater content of metallic iron was obtained when PC was used in the mixture, indicating its better performance in comparison to the NCC. For both reducing agent, at 25% in mass of NCC or PC, a greater amount of carbonaceous particles was observed in the mixtures. It was evidenced that iron ore reduction happens through the formation of two main phases, fayalite and wustite. In addition, it was observed that the metallic iron presented a more porous morphology when NCC was used.

Assessment of Reduction Behaviour of Low-Grade Indian Hematite Iron Ore Pellets by Non-Coking Coal

Assessment of Reduction Behaviour of Low-Grade Indian Hematite Iron Ore Pellets by Non-Coking Coal

Optimization of direct reduction in tunnel furnace using different resources of ferrous oxides

Nowadays it is highly desired to maximize using of existing resource and recycle waste materials. The by-product of steel being hot rolled is mill scale that disposing of it as waste material has environmental effects. Therefore, the use of mill scale in iron production is economically and environmentally beneficial. In the current work, an attempt has been made to use mill scale and iron concentrate which are not applicable to pelletized, in the reduction process with tunnel kiln for iron manufacturing. Non-coking coal and limestone were utilized as reducing agents. The reluctant to ferrous oxide ratio was kept constant during the reduction tests. The reduction process was carried out in a crucible at 1150 °C. The analyses of the metal Fe content in the reduced samples show that the mill scale can be used successfully in the direct reduction process to produce sponge iron. In the rolling mill scale-iron pellet, iron concentrate-iron pellet, and iron concentrate-mill scale mixtures, the compositions 70MS-30IP, 70IC-30IP, and 70IC-30MS were optimum. The result of XRD and STA results revealed that the optimal heat treatment setting for reducing utilized ferrous oxide mixtures is 1150 °C for 1 h.

Insight into the key kinetic steps in the pyrolysis of coking and non-coking coals, characterization of the pyrolysis products

The chemical composition, structural and plastometric properties of different-ranked coals from Mongolia deposits were studied. The non-isothermal iso-conversion Ozawa–Flynn–Wall and Friedman model-free methods were used to assess kinetic parameters and to differentiate decomposition steps. Key peculiarities of the pyrolysis kinetics of brown and bituminous coals were revealed and discussed in terms of the composition and plastometric properties. Brown coal was shown to undergo three decomposition steps with ever increasing activation energy as temperature increased because of the decomposition of thermally more and more stable molecular fragments. The pyrolysis of bituminous coals occurred in four steps, the activation energy having extreme mode of temperature dependence. An important new finding was that the temperature range of the second, major pyrolysis step well corresponded to that between the softening and re-solidification temperatures according to Gieseler plastometry. The yield and composition of the pyrolysis products obtained under isothermal conditions were also characterized depending on coal rank and temperature, and the ways for qualified utilizations were offered.

Non-Coking coal as an additive to enhance properties of groundnut shell reinforced polypropylene composites

Groundnut shells (GNS) are renewable and sustainable sources that can reinforce polypropylene for composites intended for interior building and other applications. However, the hydrophilicity, low thermal and noise insulation of GNS reinforced polypropylene (PP) necessitate the use of additives to improve properties. In this work, non-coking bituminous coal was used as an additive to improve the properties of GNS-PP composites. Up to 30% of coal particles were included and the changes in tensile, flexural properties and noise and thermal insulation were studied. Morphological analysis showed limited interaction of coal with GNS or PP and consequently, there was only marginal improvement in the mechanical properties. However, moisture sorption of the composites decreased by 25% and the limited oxygen index increased to 27 from 24 without any coal. The presence of coal increases sound absorption and the noise absorption coefficient showed high absorption at specific frequencies. Coal is an abundantly available natural material which is suitable to improve the performance of composites.

Utilization of steel plant waste and by-products in reactive coke making

Coke is used in the blast furnace as a fuel. To produce the coke, metallurgical coals are blended in the coal blend. But the reserves of the coking coals are limited in India. Hence, there is a need to use the non-coking coals in the blast furnace. However, there is a limitation for use of non-coking coals in the coal blend for coke making. So, an attempt was made in this study to increase the amount of non-coking coals in the coal blends. In the present work, briquetting technique was used for producing briquettes having non-coking coal up to 40%, and rest is slightly coking coal along with reactive materials and binders. Those samples were compressed in a hydraulic press to form briquettes which were then carbonized. The strength and reactivity tests of those coal briquettes were carried out to determine the optimum addition proportion of reactive materials and binders. It was found that 10% of reactive material was optimum for briquette making. The use of coal tar pitch and petroleum pitch binders were also studied, and their optimum values were obtained as 3%. It was also found that coal briquettes comprising of LD (Linz-Donawitz) slag and iron oxide exhibited higher reactivity as compared to other reactive materials.

Natural gums as a novel, potent, and natural additive towards coke making: a preliminary feasibility study

ABSTRACT The present investigation entails delineating the implications of using a novel and naturally sourced additive for coke making. In particular, the focus of this study was to understand the extent to which such natural gums could induce plasticity and strength to non-coking coals without inclusion of any prime coking coal, emphasizing on the importance of thermal pre-treatment as an important parameter. Experimentally, the non-coking coal was pre-treated with xanthan gum (300°C for 1 h), followed by carbonization at 600°C for 1 h. Addition of water as an additive was deduced to be beneficial in enhancing the bulk density of the coal blend. The coal blend, including non-coking coal with natural gums (10–20%) and water (10 mL in 20 g scale), produced F grade coke when treated under low-temperature Gray King (LTGK) assay conditions at 600°C. A comparative XRD and Raman analysis of raw coal and coke demonstrated the presence of graphitic content in the resultant coke only. FTIR results showed the absence of small molecular fragments, thus substantiating semi-coke formation during the re-solidification stage. The present invention holds significant industrial viability toward production of coke from non-coking coal without inclusion of any prime coking coal.

An investigation on demineralization induced modifications in the macromolecular structure and its influence on the thermal behavior of coking and non-coking coal

Eight coking and non-coking coals have been studied by Wide Angle X-ray Scattering (WAXS), Fourier Transform Infrared Spectroscopy (FTIR), and TG/DTG (Thermogravimetry/Derivative Thermogravimetry) – DSC (Differential Scanning Calorimeter). The FTIR study shows that the demineralization treatment significantly influences –OH, aliphatic (–CH3, –CH2), aromatic (C=O), and aromatic nucleus (C=C) functional groups of the raw coals. The structural parameters like interlayer spacing (d002), crystallite size (Lc), lateral size (La), aromaticity (fa)XRD, and rank (I26/I20) are determined from WAXS. The WAXS results of demineralized coal show that d002 (range 3.75–3.51 Å) decreases, but (fa)XRD (range 0.69–0.88) increases with the increase of elemental carbon percentage (Cdaf) and rank of coals. The combustion and kinetic parameters of these coals have been evaluated by TG/DTG – DSC analysis. The ignition temperature (Ti), DTG Tpeak, DSC Tpeak, and burnout temperature (Tb) vary in the range of 338–410 °C, 475–551 °C, 490–555 °C, and 579–641 °C, respectively for demineralized coals however variations of these parameters for raw coals are 345–361 °C, 462–621 °C, 467–631 °C, and 560–675 °C, respectively. The TG/DTG – DSC and FTIR results show that demineralization influences the thermal behaviors and functional groups vis-à-vis structural moieties of coals.

Pilot test of low-rank coal pyrolysis coupled with gasification to hydrogen-rich gas for direct reduced iron: Process modeling, simulation and thermodynamic analysis

A Coal-Coke-Hydrogen-Iron (CCHI) system, low-rank coal pyrolysis coupled with gasification based on pilot test to hydrogen-rich gas for direct reduced iron (DRI), was proposed. The new process creatively proposes to blend the pyrolysis gas produced by pyrolysis of non-coking coal with the gasification gas produced by gasified coke to obtain the reducing gas that can meet the requirements of the DRI technology, addressing the problems of overcapacity in the coking industry and high carbon emissions in the steel industry. A strategy of partial cycle of top gas (rich in H2 and CO) from the shaft furnace is adopted to improve gas utilization and reduce carbon emissions, which is named as CCHI system with top gas cycle (CCHI-WTC) system. The key operation parameters and conditions such as steam/coke ratio, oxygen/coke ratio, reforming ratio and circulation ratio are optimized at 0.98, 0.43, 1.00 and 12.33 %, under which the energy consumption per unit product, exergy loss per unit product and greenhouse gas unit product emission of CCHI-WTC system can reach 15.13 GJ/t, 7.85 GJ/t and 761.50 kg/t, being reduced by 24.16 %, 20.14 % and 50.01 % compared to the traditional Coking-Blast furnace ironmaking process, respectively. This work provides a new low-rank coal application approach and breaks down the industry barriers of coal chemical industry and metallurgy.

Mineralogical Study of Low and Lean Grade Iron Ore Fines during Slow and Rapid Reduction Roasting

Abstract The present study focuses on the mineralogical aspects and roasting of iron ore (Fe: 55.4%) fines in both fixed bed and fluidized bed roaster. Goethite is the dominant mineral phase in this low-grade iron ore containing hematite, silica and alumina. Such ore was roasted at a constant temperature of 900°C, with non-coking coal of 20% at residence time ranging from 15 to 60 minutes at intervals 15-minute in the fixed bed and 2 to 8 minutes at intervals 2-minute in the fluidized bed reactor. Non-coking coal was utilized as a reductant in the reduction reaction. A high-grade iron ore concentrate was subsequently extracted using Low Intensity Magnetic Separation (LIMS) from the roasted ore. Phase changes in both cases were different due to the difference in the mechanism of reduction. In the fixed-bed reduction roasting phase, transformation occurs as Goethite – Hematite – Magnetite – Wustite, whereas in a fluidized bed, it has followed Goethite – Hematite – Magnetite – Maghemite route. The maghemite phase formed during the fast reduction process due to reoxidation of the reduced magnetite. The wustite phases are reported in the nonmagnetic fractions during LIMS, lowering the yield. On the other hand, the maghemite phase is reported to the magnetic portions. It has a simple cubic structure like magnetite, which increases the yield in the fast reduction roasting process. The results show that 65.85-grade iron ore can be obtained after 30 minutes of residence time with a recovery of 51.5% from the fixed bed and 62.17-grade iron ore can be obtained after 4 minutes of residence time with a recovery of 53.2 % from the fluidized bed.

Beneficiation of Clay-Rich High-LOI Low-Grade Iron Ore Fines: Assessment of Conventional Deep Beneficiation and Magnetization Roasting Using High-Ash Non-coking Coal

Beneficiation of Clay-Rich High-LOI Low-Grade Iron Ore Fines: Assessment of Conventional Deep Beneficiation and Magnetization Roasting Using High-Ash Non-coking Coal

Effect of secondary gas-phase reactions (SGR) in pyrolysis of carbon feedstocks for anisotropic carbon materials production – 1: Controlling SGR to modify intermediate coal tar species to improve pitch anisotropy

To meet the increasing demand for graphitizable carbon products, such as needle coke and carbon fiber, more carbon feedstocks capable of forming anisotropy should be utilized. Non-coking coals are widely available but are not typically suitable for producing anisotropic carbons due to lacking proper coal chemistry. This work used secondary gas-phase reactions (SGR) during coal pyrolysis to improve the coal tar chemistry of a non-coking coal for anisotropic carbon production. SGR pyrolysis temperatures and residence times were varied (T = 800–900°C and τ = 0–2.5 s), and analysis of the intermediate coal tar products showed that as these SGR pyrolysis conditions increased, the oxygen and aliphatic concentrations decreased, whereas aromatic contents and molecular weights increased. Without any SGR, microscopy of the thermally-treated coal tar pitch product revealed that the coal tar pitch was isotropic; however, upon using increased SGR pyrolysis conditions, the resulting coal tar pitch samples substantially increased in the percentage and quality of anisotropy formation. The products' analyses show clear trends of modified chemical properties in the intermediate coal tar and improved anisotropy results. Thus, the results presented in this work show that by controlling the SGR during pyrolysis of a non-coking coal, this approach can modify the coal tar chemistry towards a precursor more suitable for quality anisotropic carbon material production.

Evolution of Opencast Mines in the Raniganj Coalfield (India): An Assessment through Multi-temporal Satellite Data

Abstract Surface mining is the dominant driver of land use land cover (LULC) change in the Raniganj coalfield region in West Bengal, India. Owing to its multifaceted consequences on soil, water, and landholders, assessment of spatio-temporal changes in mining areas has become important. The oldest coal mine of India, Raniganj coalfield has been producing superior quality non-coking coal for the last 246 years. To reduce the cost per unit production of coal, the mining authority prefers the opencast method over underground mining. The mushrooming growth of opencast mines in this coalfield causing huge waste dumps, depletion of vegetated surface, changing slope and drainage pattern, soil erosion, and degradation of environmental quality. With this background, the present study examines the spatio-temporal changes and evolution of opencast mines using multi-temporal Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) datasets of 1991, 2001 and 2014. Further, the study assessed the dynamics of mining patches and their characteristics through spatial metrics analysis. The LULC maps reveal good agreement with in-situ observation as verified by overall accuracy (≥85%) and Kappa (≥0.75) statistics. The study showed that mining areas have increased rapidly during the period and the growth has occurred by depleting the forest, sparse vegetation, and agricultural land. It is also noteworthy that the rate of growth in mining areas was comparatively higher during 2001-2014 than in 1991-2001. The change of dynamics of LULC revealed that more than 70% of the active mines was excavated after 2001. It is also observed that patch parameters, i.e. area, perimeter, shape, and density of the mining patches have changed with time that certainly establishes the dynamic nature of mining patches. The unprecedented growth of mining areas during the last decade has been a serious matter of concern from the ecological perspective of the area.

Thermodynamic Analysis of Electric Arc Furnace Dust Reduction by Volatile Matter of Non-Coking Coal

Thermodynamic Analysis of Electric Arc Furnace Dust Reduction by Volatile Matter of Non-Coking Coal