Coal Petrography

Coal petrography is a microscopic technique used to determine a coal’s rank (degree of coalification) and type (amount and class of macerals). Producers and users of coal and coke rely on SGS, the 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.

Macerals in coal are analogous to minerals in igneous rocks and are determined by examining polished specimens of minus 20 mesh prepared coal. Rank is determined by measuring the percent light reflected by 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.

SGS petrographic experts are part of our global network of mineralogists and experts in microscopy, digital imaging and state-of-the-art automated mineralogical capabilities. Information gained through our analyses identifies:

• Optimum end-use and market potential for your coal
• Identification of contaminants in the original coal sample and any that might have been accidentally introduced during shipment
• Detection of oxidized coal
• Strength of coke samples
• Coal blend percentages
• Changes in the quality of your coal sample over time
• Determination of tar quality

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 reflective 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 and pictographic services to determine the percentage of each 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. Quinoline insoluble residues are solid carbon particles created in coal tars during carbonization that strongly affect the characteristics of products that are produced later.

Summary

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, as well as complete coke and by-product analysis using computer controlled DIS. 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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  Petrographic Analysis

  published 02/29/12

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