Mining and Metallurgy Volume 31-36 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ...constructing the working-parts of steel and phosphor-bronze, it is possible to make briquettes dry enough to pass directly into a blastfurnace at the rate of 600 to 800 tons per day for each machine employed, at a cost of less than half that of the die-and-plunger system. XXIII. Chlorination. Chlorination is confined almost entirely to sulphide gold-ores carrying so little silver that its loss may be disregarded, and which require a preliminary roasting before treatment. The early methods of tank-leaching have all been superseded by barrel-chlorination, and in some of the latest plants chlorine is produced by electrolysis instead of by the decomposition of bleaching-powder with sulphuric acid. The largest plants operating under this system treat customores, and the stress of competition, together with the necessity of handling constantly increasing tonnages, has brought about great improvements in both machinery and methods. The most desirable features of this process of gold-extraction are the high percentage recoverable, and the rapidity with which clean-ups can be made, rendering it easy at all times to know exactly what results are being obtained. The largest plants operating under this system are situated in Colorado City, Colo., where two mills owned by one concern have an aggregate capacity of 800 tons per day. XXIV. Cyanidation. While the first patent for extracting gold from its ores by cyanide solutions was issued in 1867, it was not until McArthur and Forest took it up in 1889 that practical results of any value were obtained. Since that time the use of the process has increased by leaps and bounds in all of the principal gold-producing countries, and to-day it is the principal factor in the world's steadily increasing gold-production. Cyaniding ...