Macerals Characterization and Separation in Coal Processing
Summary
Coal macerals are the microscopic organic constituents that dictate the physicochemical behaviour of coal during utilisation and processing. Classified into vitrinite, inertinite and liptinite groups, macerals differ in reflectance, density, porosity and chemical functionality. Characterisation typically employs reflected-light microscopy, Raman spectroscopy and fluorescence imaging to quantify maceral composition and rank. These insights inform separation strategies that exploit contrasts in surface chemistry and mechanical strength. Conventional techniques such as dense medium separation and froth flotation remain central to selectively concentrating valuable maceral fractions. Innovations in pretreatment—cryogenic quenching, high-pressure grinding and electrostatic separation—enhance maceral liberation and reduce fine coal losses. Advanced image analysis and machine learning tools are increasingly applied to automate maceral identification and to optimise process control. By isolating specific maceral types, it is possible to produce tailored feedstocks for combustion, gasification and advanced carbon materials, while reducing mineral impurities and lowering carbon-intensive emissions. Globally, refining maceral-targeted separation supports more efficient resource use, enables value-added applications of low-rank coals and aligns coal processing with stringent environmental and sustainability goals.
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Macerals Characterization and Separation in Coal Processing publication trend
The graph below shows the total number of articles in macerals characterization and separation in coal processing across all publications each year (not limited to Nature Index journals).
Technical terms
Maceral: A microscopic organic component of coal distinguished by optical and chemical properties.
Vitrinite: A maceral group derived from woody plant tissue, characterised by moderate reflectance and high reactivity.
Inertinite: A maceral group formed under oxidising conditions, notable for high reflectance, density and low reactivity.
Liptinite: A group of hydrogen-rich macerals originating from spores and resins, exhibiting strong fluorescence.
Floation: A separation technique that exploits differences in surface hydrophobicity to float organic particles.
Dense medium separation: A gravity-based method that separates particles by density using a finely suspended heavy medium.
Petrographic analysis: The microscopic examination of coal to determine maceral composition, rank and textural features.
References
- Study on the Liberation of Organic Macerals in Coal by Liquid Nitrogen Quenching Pretreatment. Minerals (2020).
- Role of maceral groups in coal beneficiation: A short review. Physicochemical Problems of Mineral Processing (2024).
- Oily Bubble Flotation of Coal Macerals of Shendong Jurassic Coal. Minerals (2024).
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