MANUAL Published: 11 December 2014
MNL572013001106

Chapter 6 | Ultimate Analysis

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Ultimate analysis of coal and coke is defined in ASTM D3176 as the determination of the carbon, hydrogen, nitrogen, and sulfur in the material, as found in the gaseous products of its complete combustion, the determination ash in the material as a whole, and the estimation of oxygen by difference. The carbon determination includes that present in the organic coal substance and any carbon originally present as mineral carbonate. The hydrogen determination includes that in the organic materials in coal and in all water associated with the coal. All nitrogen determined is assumed to be part of the organic materials in coal. For practical reasons, sulfur is assumed to occur in three forms in coal: as organic sulfur compounds; as inorganic sulfides, which are mostly the iron sulfides pyrite and marcasite; and as inorganic sulfates. The total sulfur value is used for ultimate analysis.

Moisture is not by definition a part of the ultimate analysis of coal but must be determined so that the analytical values obtained can be converted to bases other than that of the analysis sample. In other words, analytical values may need to be converted to an as-received or a dry basis. When suitable corrections are made for the carbon, hydrogen, and sulfur derived from the inorganic material, and for conversion of ash to mineral matter, the ultimate analysis represents the elemental composition of the organic material in coal in terms of carbon, hydrogen, nitrogen, sulfur, and oxygen.

The current practice in most coal and fuel laboratories is to determine carbon, hydrogen, nitrogen, and sulfur using instrumental methods. The classical methods for determining these elements have been withdrawn from publication because of the lack of use. Several of the instrumental methods that are now used were developed using chemical information and procedures found in the classical methods. In the following sections the chemical processes used in the classical ASTM methods will be discussed to gain a better understanding of the current test methods.

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Developed by Committee: D05
Pages: 49–65
DOI: 10.1520/MNL572013001106
ISBN-EB: 978-0-8031-7063-6
ISBN-13: 978-0-8031-7062-9