Coal Geology

The rare earth elements (REE) possess a beneficial combination of chemical and physical properties, making them valuable for most advanced branches of engineering and technology. Alternative sources of REE are desirable due to limited reserves of conventional REE containing minerals over the world combined with disproportionate supply over demand in the commodity markets. This study investigated the occurrence of REE and carbon nanotubes (CNTs) in Cretaceous Nigerian coals for prospective industrial applications. Results show that the coals' crystalline mineral matter comprises quartz, kaolinite, and illite with minor quantities of feldspar, hematite, magnetite, calcite, dolomite, which indicate detrital mineral origins. Elemental relationships (such as Al 2 O 3 /TiO 2 , Cr/Th vs. Sc/Th, and Co/Th vs. La/Sc) suggest sediment-source regions with mafic, intermediate or felsic compositions. REE are either strongly fractionated or characterized by light-enrichment along with outlook coefficient (Coutl) values that suggest the coals are prospective substitute sources for REE and yttrium (REY) recovery. Several minerals including jarosite, goethite, epsomite, ferrohexahydrite, natrojarosite, rozenite, and gypsum were detected in trace amounts. REE mineral phases were not identified but only amorphous phases containing Ce, La, Nd, Th, Pr, Sm, Gd, Tb, Dy, Ho, and Hf. Maceral composition (high vitrinite), presence of ironcontaining minerals (hematite and magnetite), high carbon contents, reduced volatile matter and low ash content favoured the formation of naturally occurring multi-walled carbon nanotube (MWCNTs) structures in Maiganga (MGA) coal. Hence, the present study is the first scientific report on the naturally occurring REEs and MWC nanophases in Cretaceous coals from the Benue Trough.

New mapping at Anglesea coal mine, and coal resource and deep groundwater drilling have
provided new perspectives on the economically important Eastern View Group coal-bearing
sedimentary succession in the onshore Torquay Basin. In the Anglesea Syncline, the upper 35 m-thick
brown-coal seam of the Eastern View Group is overlain by a low-angle unconformity. Units overlying
the coal seams include high-energy, cross-cutting sand channels of the Boonah Formation and lower
energy channel and interchannel systems of the overlying Salt Creek and Anglesea Formations. The
mine section can be correlated from borehole data with the Eastern View Group and Demons Bluff
Group exposed in coastal cliff sections along the adjacent Anglesea to Torquay coast. Recently drilled
coal and groundwater exploration bores provide new data on the extent of the coal measures in
the Anglesea area, and details of the underlying Tertiary succession that include typical Otway Basin
units such as the Pember Mudstone and Pebble Point Formations. The stratigraphy below the coal
measures suggests that the Otway Ranges were not present during Palaeogene times. The rank of
the brown coals on and around the Otway Ranges is higher than any other Tertiary coals in onshore
Victoria, and they preserve similar patterns of rank distribution to the high-rank black coals in the
underlying Lower Cretaceous Otway Group. Evidence for large overburden thicknesses is lacking,
and the high ranks may have been augmented by higher than normal geothermal gradients in the
Early Tertiary. Comparisons between the observed depositional cycles, sequence–stratigraphic cycles,
and worldwide coastal onlap curves suggest that the observed disconformity boundaries are
sequence boundaries that provide a chronostratigraphic framework. Sequences present may include
TB4.1–4.5 in the overburden units, and TB 2.4–3.6 in the coal-bearing interval.

... pinned. And of course, apart from its stylistic virtues, Lost Mountain happens to be important." —John Jeremiah Sullivan, author of Blood Horses "Compelling, considered, and courageous. . . ... coal. "That's what it's all about," John said. ...

Keywords : Coal cores, Bhivakund block, Wardha Valley Coalfield, Central India The study of borehole coal cores involves visual separation of different bands present in the coal seams and its characterisation for qualitative and quantitative estimation of exploitable reserves of the coal block. The band wise study of the coal seams of Bhivkund block shows that the seams are inter-banded with coal and dirt bands viz. shaly-coal and carbonaceous shales of varying thicknesses interspersed with sporadic occurrences of shale, sandy shale and sandstones. The coal seam can be split into three sections and the dirt bands usually occur within the partings between these sections. Geochemical, proximate and ultimate analyses and gross calorific value of coal samples indicate that the coal is high in moisture (M%) content, variable ash content (Ash%), medium to high volatile, sub-hydrous and sub-bituminous in rank with variable sulphur contents. The coal is non-caking in nature and can be used for power generation and in local industries.

Results from coal-exploration drilling in the onshore part of the Port Phillip Basin, Victoria, have established
stratigraphic and age correlations of the Lower Miocene Werribee Formation brown coal
deposits at Bacchus Marsh to similar brown coals at Altona. The coal deposits occur in a northwest–
southeast structural depression (the Parwan Trough) that appears to be a southeast continuation of
the Ballan Graben. Recent drilling for potential coal-bed methane in the trough has provided new
data on the deeper stratigraphy not penetrated by earlier drilling, including recognition of an Upper
Cretaceous to Eocene Yaloak Formation coal-bearing interval, similar to the Anglesea area, Ballan
Graben and Lal Lal Basin. Up to 200 m of coal-bearing sediment and minor volcanics underlie the
Miocene coal measures. A marine facies transition takes place between the Miocene coal swamps
of the Parwan Trough, through barrier sands west of Werribee, to carbonate facies near Geelong. To
the south beneath Port Phillip Bay, a similar transition probably occurs between coal swamps of the
Parwan Trough and fully marine carbonate environments of the contiguous Sorrento Graben. The
palaeogeographical reconstructions suggest a similar coal-to-carbonate facies transition as in the
adjacent onshore Gippsland Basin

New mapping at Anglesea coal mine, and coal resource and deep groundwater drilling have provided new perspectives on the economically important Eastern View Group coal-bearing sedimentary succession in the onshore Torquay Basin. In the Anglesea Syncline, the upper 35 m-thick brown-coal seam of the Eastern View Group is overlain by a low-angle unconformity. Units overlying the coal seams include high-energy, cross-cutting sand channels of the Boonah Formation and lower energy channel and interchannel systems of the overlying Salt Creek and Anglesea Formations. The mine section can be correlated from borehole data with the Eastern View Group and Demons Bluff Group exposed in coastal cliff sections along the adjacent Anglesea to Torquay coast. Recently drilled coal and groundwater exploration bores provide new data on the extent of the coal measures in the Anglesea area, and details of the underlying Tertiary succession that include typical Otway Basin units such as the Pember Mudstone and Pebble Point Formations. The stratigraphy below the coal measures suggests that the Otway Ranges were not present during Palaeogene times. The rank of the brown coals on and around the Otway Ranges is higher than any other Tertiary coals in onshore Victoria, and they preserve similar patterns of rank distribution to the high-rank black coals in the underlying Lower Cretaceous Otway Group. Evidence for large overburden thicknesses is lacking, and the high ranks may have been augmented by higher than normal geothermal gradients in the Early Tertiary. Comparisons between the observed depositional cycles, sequence–stratigraphic cycles, and worldwide coastal onlap curves suggest that the observed disconformity boundaries are sequence boundaries that provide a chronostratigraphic framework. Sequences present may include TB4.1–4.5 in the overburden units, and TB 2.4–3.6 in the coal-bearing interval.

Underground coal gasification (UCG) is a promising option for the future use of un-worked coal. UCG permits coal to be gasified in situ within the coal seam, via a matrix of wells. The coal is ignited and air is injected underground to sustain a fire, which is essentially used to “mine” the coal and produce a combustible synthetic gas which can be used for industrial heating, power generation or the manufacture of hydrogen, synthetic natural gas or diesel fuel. As compared with conventional mining and surface gasification, UCG promises lower capital/operating costs and also has other advantages, such as no human labor underground. In addition, UCG has the potential to be linked with carbon capture and sequestration. The increasing demand for energy, depletion of oil, and gas resources, and threat of global climate change have lead to growing interest in UCG throughout the world. The potential for UCG to access low grade, inaccessible coal resources and convert them commercially and competitively into syngas is enormous, with potential applications in power, fuel, and chemical production. This article reviews the literature on UCG and research contributions are reported UCG with main emphasis given to the chemical and physical characteristic of feedstock, process chemistry, gasifier designs, and operating conditions. This is done to provide a general background and allow the reader to understand the influence of operating variables on UCG. Thermodynamic studies of UCG with emphasis on gasifier operation optimization based on thermodynamics, biomass gasification reaction engineering and particularly recently developed kinetic models, advantages and the technical challenges for UCG, and finally, the future prospects for UCG technology are also reviewed.