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(A) Vitrinite maceral altering into mesophase sphere and mosaics; (B) Mesophase spheres, mosaics and devolatilzation pores; (C) Natural coke groundmass with devolatilization pores and cracks; (D) Same field showing mesophase spheres mosaics and fine flow structure (E) Natural coke groundmass showing flow structure and vesicles; (F) Flow structures and mosaics of different sizes with prominent anisotropy, fine flow structure and mineral matter under crossed (Singh, et al., 2007).
Source publication
The effects of igneous intrusion on coal are observed in various parts of the world. It is found that igneous intrusions have altered the quality and characteristics, especially the coke ability of the coals. It has been estimated that a large quantity of heat affected (jhama) coal is reserved in the Jharia collieries of India. Nowadays, apart from...
Context in source publication
Context 1
... are matrix (groundmass) formed by total alteration of vitrinite and liptinite, macerals of the inertinite group with preserved structures and textures visible in the unaltered coal and new components, which are partly high-carbon material and partly mineral matter, formed due to the intrusion [1]. Figure 4 presents some micrographs of jhama coal taken from Jharia coal field. Fig. 3. Field photograph of jhama coal. ...
Citations
... A large amount (5,313 million tons) of thermally metamorphosed coal has been found in the Damodar Valley coalfields (Jharia) in India, which is about 2% of India's total coal deposits. The thermally altered coals are known by various names, such as geological coke or natural coke or cinder or Jhama coal (in India), etc. (Nag et al. 2009(Nag et al. , 2015. Natural coke is derived from coking coal under in-situ conditions due to intense magmatic-induced heat and overburden pressure (Kwiecińska and Petersen 2004;Singh et al 2007). ...
... This phenomenon is called weathering. The heat-altered coal of India is commonly termed Jhama coal or baked coking coal (Kwiecińska and Petersen 2004;Michalski et al. 1997;Nag et al. 2009Nag et al. , 2011Neil 2016;Singh et al 2007). Jhama coal has a composition of ash: 20-40%, volatile matter: 5-15%, fixed carbon: 60-70%, moisture: 0.6-2% with total carbon of 70-90% and below 0.4% sulfur (Nag et al. 2011;Singh, Sharma, and Singh 2008). ...
Magnetite ore pellets oxidize to hematite during their induration in a mild oxidizing atmosphere of strand which produces internal heat in the pellet and enhances diffusion bonding. Hematite ore pellet does not have such oxidation. Therefore, hematite pellets require a much higher induration temperature (>1300°C). To reduce the induration temperature requirement (maximum temperature of the strand) of hematite pellets, investigators have added several additives, namely, coke fines, coal fines, charcoal, anthracite, Jhama coal, blast furnace flue dust, etc. as carbon sources. Carbon in these materials oxidizes in the mild oxidizing atmosphere of the strand and provides in-situ exothermic heat which helps in the bonding of pellets. Investigators have also added lower iron oxides containing materials for this purpose, namely, magnetite ore, mill scale, and sludge which oxidize and provide diffusion bonding and exother-mic heat. However, each of the above materials has a different character of reaction based on its chemistry, particle size and shapes, surface morphology, distribution, and concentration. Therefore, they affect differently on the pellet properties. Several studies reported so far on the effects of each material, their optimum requirement, advantages, and disadvantages are discussed along with their comparative analysis. This will help identify the appropriate additive and their amount of requirement in hematite pellets.
... Following intrusion, a major change in the evacuation of volatile matter (VM) is observed that results in deposition of carbonaceous matter which is the reason heat affected coal has been generally observed to show an increase in ash and fixed carbon (Nag et al. 2011). Macroscopical observation revealed that Jhama coal is dull, hard and compact with its pores either empty or filled with mineral matter (Nag et al. 2009). A Jhama coal, also known as natural burnt coke has little VM which makes it non-combustible friendly (Singh et al. 2016). ...
... Having quite difficult washability characteristics due to uniform distribution of mineral matters in the partially carbonized coal matrix, its large scale application in coke making is a challenging issue (Chakladar et al. 2020). It was reported that Jhama coal had to undergo certain coal preparation practise to improve its quality as blend (Nag et al. 2009(Nag et al. , 2011. Total reserves of Jhama coal, in the Jharia coalfield alone currently stands at 5313 Mt. ...
Onsite mine fire generates large volumes of heat-affected coal in Jharia coalfields, India. Direct utilization of such heat-affected coal in thermal utilities is not feasible as such coal does not have the desirable volatile matter required for combustion. In the present work, experimental studies have been carried out to investigate the possible utilization of such heat-affected coal in thermal utilities by blending with other coal. Heat-affected coal (31% ash and 5300 kcal/kg GCV) collected from Jharia coalfield were blended with thermal coal (28% ash and 5650 kcal/kg GCV) in different ratios of 90:10, 80:20, 70:30 and 60:40 to identify the desirable blend ratio for burning of blended coal in thermal utilities. Burning characteristics of all the coals were carried out using TGA. Various combustion parameters such as ignition temperature, peak temperature, burnout temperature, ignition index, burnout index, combustion performance index, rate and heat intensity index of the combustion process and activation energy were evaluated to analyse the combustion process. Experimental and theoretical analysis shows the blend ratio of 90:10 can be used in place of only thermal coal in utilities to reduce the fuel cost.
... When the in situ bedrock was intruded the hot magma thermally altered the surrounding country rock and modifying the properties of the coal and thereby affecting its use, saleability and price. Heating coal drives off volatile matter and changes the coal's uses (Nag et al, 2009), for example low volatile coals have an increased calorific value (energy per unit of volume) but are difficult to ignite. The application of continued heat "burns" the coal and the ash content increases markedly. ...
Paper submitted for Technical Paper Competition, Parsons Brinckerhoff (Runner Up)
Magmatic intrusion of coal results in plethora of alterations in both chemical and physical properties. Such alterations affect both organic and inorganic components in coal in addition to surface chemistry modifications. Beneficiation processes largely depends on the surface chemistry of coals. Heat affected coals are challenging to beneficiate owing to their unique surface properties compared to bituminous coals. In our present work, we have successfully beneficiated heat altered coal from Jharia Coalfield, India, with 28% ash content. The proposed beneficiation process combining micronization and oil agglomeration could reduce the ash content to 10%, which is approximately 60% reduction from parent coal. The organic matter recovery has been around 80% for different particle sizes along with enhancement of volatile matter content from 7% in parent coal to nearly 27% in agglomerated clean coal.
Examples of anthropogenic pyrometamorphism are numerous and often closely analogous to natural pyrometamorphic processes and products. In this chapter, products and conditions of anthropogenic and biomass pyrometamorphism are described and include: bricks and ceramics derived from a variety of compositions; fused rocks associated with burning spoil heaps, in situ gasification; slags produced from non-metallic blast furnaces, iron ore smelting, surface burning, drilling and artificial fulgurites.
