Engineering and Mining Journal

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I have a ton of these, they date from the 1990s and they are in a pile 30 inches high. Here is a description of one of them: E&M (Engineering and Mining Journal) NOVEMBER 1990 VOLUME 191 NUMBER ELEVEN Contents Trona—a tale of two companies.....................20 Oldest and youngest expand aggressively, producing a mineral first used by the Egyptians over 6,000 years ago. Why are we content with ninety percent? ................26 Metallurgists accept 90% flotation recovery. Why? Gains to be made from extra recovery usually far exceed those from investment in added capacity. Minorca fluxed-pellet project.......................30 Major modifications do not have to be major headaches—in fact they can be done ahead of schedule and under budget. Salt from the pepper island........................33 Belts are a production lifeline—especially where output peaks at over 2,000 st/hr. Cover: While longwall is breaking into trona, boring machines—once thought obsolete in U.S. coal mines—have been revamped. They are very productive in the world's largest geologic source of natural soda ash. The 1,582 hp, 92-st, Eickhoff EDW-450/1100-L, double-ended, ranging-shearer (supplied with 4,160 v) is used on the only non-coal longwall in the United States. It is one of seven of this large model in use in the Western World [ one in Australia plus five on three faces in the Saar region of Germany]. Main articles: Escondida to be world's third-largest copper producer............. 11 The Klondike—Soviet style........................... 12 A golden career and challenges in South Africa................. 13 Bolivian investment law passed after three years................ 13 Calendar............5 Exploration roundup ......9 This month in mining.....11 This month in coal .....16A Coal equipment.......16G Markets............17 Advertiser index Operating ideas ....... 43 Suppliers news........ 46 Product development..... 48 New products ........ 52 People............ 55 Bulletins ........... 56