The majority of coke produced in the world is consumed reducing iron ore in blast furnaces to produce molten iron. Coke strongly influences blast furnace productivity. Steel mills may perform coke tests to benchmark a particular coke against other cokes, to evaluate the quality of a blend, or to understand the quality of a new coal. Similarly, coal sellers my perform coke tests to demonstrate coke quality to coal buyers, to evaluate new deposits of coal or to test potential blends.
This document focuses on tests commonly used by coal sellers and buyers operating in the seaborne metallurgical coal markets.
Coal petrography is performed on a coal sample with a 1mm particle top-size that has been crushed in a particular way to produce a minimum of fines. This coal sample is mixed with a binder, such as acrylic resin, and the mixture is placed into a mold and allowed to set. Once the petrographic block is solid, it is removed from the mold and subsequently cut and polished to produce a surface that is free of scratches and relief. This is placed under a reflected light optical microscope to perform the analyses.
There are two standard coal petrographic analyses:
ALS also perform non-standard petrographic analyses:
To ensure ALS delivers reliable results, ALS' petrographers are evaluated and certificated by the International Committee for Coal and Organic Petrology (ICCP). The petrography unit is also accredited to ISO 17025 for maceral analysis according to AS 2856.2 and ISO 7404.3 and to vitrinite reflectance according to AS 2856.3 and ISO7404.5.
Coal petrography is not usually performed as a standalone test but rather as a component in a comprehensive testing program including pilot-scale coal carbonization tests. ALS has well-equipped laboratories capable of performing a broad range of coal analysis through an extensive coal laboratory network.
Materials submitted for analysis are retained free of charge for a limited time, starting from the day the final Certificate of Analysis is issued. Generally, reject material and bulk pulp samples (> 250g) are stored for 45 days, and pulp samples are stored for 90 days free of charge.
Part of the sample submittal form is dedicated to how you would like your samples to be dealt with after analysis. Options include disposal, storage or return of each fraction. Please ensure this part of the sample submittal form is filled out so that we can record this information in our system when samples are received.
For larger samples, ALS provides a pilot-scale coal preparation plant with the capability of processing between 1.5 and 20 tonnes of coal.MORE INFORMATION