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Coal Petrography

Coal petrography is a microscopic technique used to determine a coal’s rank (degree of coalification) and type (amount and category of macerals).

Producers and users of coal and coke rely on SGS, an industry leader in coal petrology, for independent, globally recognized coal petrographic analysis. Accurate petrographic analysis is an important tool to evaluate bituminous coals and coal blends and their ability to produce blast furnace coke.

Coal petrography is performed by examining polished specimens of minus 20 mesh prepared coal. Rank is determined by measuring the percent reflectance of the maceral vitrinite. Type is determined using a point count procedure to obtain the volume percent of the various coal macerals, or fossilized plant remains. Petrographic analysis can also be used to determine whether contaminants are present in the coal and to detect oxidized coal in the sample.

Digital Imaging System (DIS)

SGS uses a Digital Imaging System (DIS) to determine the percentage of each coal in a blend or to compare changes in quality of individual coals or blends over time. This system consists of a Zeiss microscope and digital camera, a computer controlled motorized stage, and software to compile and analyze the data. The DIS gathers over 5 million reflectance values for a single coal and over 9 million for multi-seam coals or coal blends to generate a unique reflectogram for each sample. Cursors can be set to isolate the various ranks of coal in a blend and determine their corresponding percentages.

Coke and By-Product Petrography

SGS provides coke pictographic services to determine the percentage of each rank of coal in your blend, troubleshoot quality problems and to evaluate how coking operations impact your final product. In addition, we can evaluate by-product quinoline insoluble (QI) residues to determine coal tar quality.


A clear understanding of the characteristics of your coal blend is necessary to evaluate how coking operations will impact your final product. SGS provides a comprehensive range of coal, coke and by-product petrographic services in accordance with recognized global standards. Our experienced technicians will provide you with expert rank and type determination on your coal or coal blend as well as complete coke and by-product analysis. Leverage our depth and breadth of technical expertise in coal petrology and digital imaging to give you the competitive advantage you need to grow your business.

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  • SGS Argentina SA

Tronador 4890 - Piso 3°,


Buenos Aires, Argentina