12 El Salvador (2) Guatemala (21 Haiti (51 Jamaica (2) Paraguay ( 1) Peru (1) n. a. n. a. -... n. a. n. ae 9 97 n. a. n. a. 4.2. n. a. n. a. 126 n. a. n. a.
A. SONE COAL BRIQUETTING TECHNIQUES MAKE COAL AN ATTRACTIVE FUEL-MOOD SUBSTITUTE BY CONVERTING IT INTO A SMOKELESS, COMPACT, STABLE, AND INEXPENSIVE FORM OF RIEL. <strong>Coal</strong> is often described <strong>as</strong> a 'tdirtyfl fuelr emitting smoke that is offensive <strong>and</strong> contai ni ng constituents that are harmful to human health. Moreover, sune raw coals are highly friable <strong>and</strong> are not e<strong>as</strong>ily h<strong>and</strong>led or distributed in their natural state. However, by briquetting <strong>and</strong> carbonizing when necessary, coal can be put into a relatively clean, compact, <strong>and</strong> stable <strong>for</strong>m <strong>for</strong> use. The resulting fuel is also not expensive. B. COAL BRIQUElTING HAS BEEN SHCWN WORLD-WIDE TO BE A TECHNCLGY CAPABLE OF USING COPL OF VARIOUS GkADES AND PRODUCING BRIQUETTES W IM DIFFERENT CHARACTERISTICS FOR DIFFERENT USES. <strong>Coal</strong> brlquetting is a process z~y which raw coal is compacted into uni <strong>for</strong>m, usual 1 y hard, <strong>and</strong> 1mpac:t- res1 stant aggl omerati ons, maki ng it more suitable <strong>for</strong> use? transport, <strong>and</strong>/or further processing. It h<strong>as</strong> been practiced <strong>for</strong> many years, at le<strong>as</strong>t since the beginning of this century.Cl21 It is also a technology that ha5 been researched worldwide, in such widely dlspersed places <strong>as</strong> Germany, USSR, Austral ia, Korea, India, <strong>and</strong> the United States. The wide extent of the research h<strong>as</strong> several re<strong>as</strong>ons. First, all coals are not a1 ike, <strong>and</strong> often research h<strong>as</strong> been aimed at developing aF" improved brfquetting process <strong>for</strong> a particular coal. Second, briquetting can be done with or without an additive (binder) to help in agglmerating <strong>and</strong> giving cohesive strength to the briquette. Much research h<strong>as</strong> gone into suitable binders, <strong>as</strong> well <strong>as</strong> into processes by which briquetting can be per<strong>for</strong>med without a binder. Third, same research h<strong>as</strong> been directed at improving the properties of the briquettes, such <strong>as</strong> maintaining ignitabil ity while keeping volatile matter low <strong>as</strong> well <strong>as</strong> reducing smoke <strong>and</strong> sulfur cmissians upon burning. It should be emph<strong>as</strong>ized that there is not just a single briquetting technologyr nor wen a set of two or three or a half dozen well-defined technologies <strong>for</strong> coal briquetting. Rather, a set of parameters <strong>for</strong> the briquetti ng of coal such <strong>as</strong> tc-mperature, pressure, pressing time, binderr type of coalp type of press, pretrealnent, etc., can be varied to produce unique briquetting processes. <strong>Coal</strong> briquetti ng can be per<strong>for</strong>med on 1 ump coal or on coal fjnesr the latter appl Ication often being an attempt to salvage an otherwise w<strong>as</strong>ted product of coal h<strong>and</strong>ling. The usual process of coal briquetting 1 3