INTERNATIONAL ISO STANDARD 157 Secondedition 1996-06-01 Coal --- Determination of forms of sulfur Charbon Determination de la teneur en differentes formes de soufre ISO Referencenumber ISO157:1996(E) No reproduction or networking permitted without license from IHS Not for Resale ISO 157:1996(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies).The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be rep- non-governmental, in liaison with IsO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (lEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 157 was prepared by Technical Committee ISO/TC 27. Solid mineral fuels, Subcommittee SC 5, Methods of analysis. This second edition cancels and replaces the first edition (ISO 157:1975), of which it constitutes a technical revision. Annex A of this International Standard is for information only ISO1996 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in anyform orby any means,electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case postale 56 CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii ional Organization for Standardizatior Noreproductionornetworkingpemitedwithout licensefromIHS Not for Resale @ IsO ISO157:1996(E) Introduction For many purposes, a knowledge of the total sulfur content of a coal is sufficient, but for certain work it is also necessary to know how the suifur is distributed between the coal substance and the mineral matter. In particular, such information may be required in connection with coal classi- fication and cleaning. Sulfur is usually present in coal in three forms, viz: a) sulfate sulfur, i.e. the sulfur present in the form of inorganic sulfates; (g pyritic sulfur, i.e. the sulfur present in the form of pyrites and marca- site; organic sulfur, i.e. the sulfur present in the form of organic sulfur compounds. ili Nrouctinwokinmitewithutlefrom Not for Resale