Effects of rapid thermal alteration on coal: Geochemical and petrographic signatures in the Springfield (No. 5) Coal, Illinois Basin

An occurrence of coked bitumen, Raton Formation, Purgatoire River Valley, Colorado, U.S.A.

“…Conditions surrounding the intrusion event (maximum temperature attained, heating duration, heating rate, etc.) are not constrained and it is known that variations in these conditions can influence mosaic textures to some degree (e.g., Goodarzi and Murchison, 1978;Murchison, 2006;Rahman and Rimmer, 2014). However, despite the large number of studies on the petrography of intruded coals, there are no published examples of such a large discrepancy in resultant coke textures.…”

“…There has been some debate as to whether intruded coals always coke true to original coal rank. Compared to industrial coking conditions, those conditions associated with intrusion may result in slightly different mosaic textures (Goodarzi and Murchison, 1978;Rahman and Rimmer, 2014). In the laboratory, it has been shown that coke texture can be influenced by maximum temperature (Chaudhuri et al, 1997), heating rate (Goodarzi and Murchison, 1978;Murchison, 2006), heating duration (Brooks and Taylor, 1966;Goodarzi and Murchison, 1977;Sanada et al, 1973), and pressure (Bratek and Marsh, 1980;Chaudhuri et al, 1997;Murchison, 2006), all of which may be higher during natural coke formation.…”

“…In the laboratory, it has been shown that coke texture can be influenced by maximum temperature (Chaudhuri et al, 1997), heating rate (Goodarzi and Murchison, 1978;Murchison, 2006), heating duration (Brooks and Taylor, 1966;Goodarzi and Murchison, 1977;Sanada et al, 1973), and pressure (Bratek and Marsh, 1980;Chaudhuri et al, 1997;Murchison, 2006), all of which may be higher during natural coke formation. Therefore, there are instances where minor differences in resultant coke textures are seen in naturally formed cokes (Rahman and Rimmer, 2014) as well as multiple textures, perhaps due to multiple heating stages (Amijaya and Littke, 2006).…”

“…Coals can produce coke in nature when exposed to high temperatures associated with intrusions (via contact metamorphism) (Clegg, 1955;Cooper et al, 2007;Crelling and Dutcher, 1968;Dutcher et al, 1966;Fredericks et al, 1985;Ghosh, 1967;Rahman and Rimmer, 2014;Rimmer et al, 2009;Saghafi et al, 2008;Stewart et al, 2005). There has been some debate as to whether intruded coals always coke true to original coal rank.…”

Petrological and geochemical characteristics of Palaeogene low-rank coal on the Faroe Islands: Restricted effects of alteration by basaltic lava flows

“…The composition of coal can be affected by volcanic activity. Several authors have studied various properties of thermally altered coal from all over the world (Bussio and Roberts, 2016;Dai and Ren, 2007;Golab and Carr, 2004;Merritt, 1985;Rahman and Rimmer, 2014;Singh et al, 2007Singh et al, , 2008Wang et al, 2014;Ward et al, 1989;Yao and Liu, 2012). Ward et al (1989) categorized the layers around an igneous body into four zones: i) zone of porous cinder close to the contact; ii) zone of visibly banded cinder with remnants of the original lithotype stratification; iii) zone of heat-affected coal without porosity and other microscopic and macroscopic signs of coking; iv) zone of unaffected coal.…”