H. O. Hofman
Published: 2017-04-16
Total Pages: 686
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Excerpt from Metallurgy of Lead The first discovery of argentiferous lead ore was made in 1863 in Little Cottonwood Canyon, Utah; the first smelting of such ores was carried on in 1865 at Argenta, Mont; in 1867 similar ores were found at White Pine, Nev., and smelting was begun at Oreana, Nev. In 1869 the mines of Eureka, Nev discovered in 1864, were opened up, and the treatment of ores was begun in the following year. Next came Utah, where smelteries were erected in 1870, followed by Colorado, which came into prominence in 1878. Later Idaho, New Mexico, and Arizona were added to the list. Colorado for many years was the largest producer of lead ores, but it has been outranked by Idaho and Utah since the exhaustion of the wonderful mines of Leadville after 1890; it furnishes at present only 6 - 7 per cent. Of the country's product, and this high figure is largely due to the central smelting works of Denver and Pueblo which treat more lead ore mined outside of the state than produced in it. The manner in which prehistoric people extracted lead from ore is unknown. If we recall that oxide and sulphide ores readily give up lead when heated with charcoal, we can imagine that the accidental discovery of this fact may have led to the most primitive furnace, a small pit dug into the ground and enclosed by stones to form a small shaft. If at first such furnaces were worked by natural draft, blast (reeds, bellows) must have been applied to produce the temperature required to form slag. The furnaces (cavity 30 in. Deep, side-walls 26 in. High, 2 tuyere-openings) found in Sinai in which copper ores were smelted about 4000 b.c.1 had this form; the furnaces of Laurium were similar. In early times low shaft furnaces with natural or forced draft formed the ap paratus, and charcoal the fuel. Agricola2 states that in 1556 the inhabitants of the present Austrian province of Carinthia used what may be called a closed stall with inclined bottom for treating galena; they kindled a wood fire and charged the ore upon it, whereupon lead was liberated and, trickling down the hearth, was collected in a basin. Similar contrivances, the Log-furnace and Ash-furnace, were used in smelting ores in the Mississippi valley about 1720. These were in operation until 1836, when the first Scotch ere-hearth was erected. Percy' states that in 1730 the ore-hearth was in operation in Derbyshire, England. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
