Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. Excerpt from book: Section 3be saved with more care, the richer or more valuable the ore is. The result of dressing within the mine gives four classes of rock, or less, according to circumstances. textit{First?Worthless material, either remaining in the mine to fill up excavations, or brought to the surface on the waste .heap. textit{Second? Rich ores, when circumstances require the separation under ground. textit{Third?Middle ores, to be dressed outside; and textit{Fourth?Smalls resulting from breaking. Sec. 5. Dressing of Ores Outside the Mine. On arriving at the surface, the ore is still intermixed with rock and gangue which could not be separated from it in the mine. Generally the ore is discharged on a level ground as close to the mine as possible, in order to save the transportation of waste rock. The principal object here is the continuation of dressing by ragging, spalling and cobbing; also washing and sizing. SEC. 6. Separation by Hammers. textit{A. The Bagging is performed by steel-headed ragging hammers, from and ix to eight pounds weight. In this operation, breaking the rock smaller, a part of it and of the gangue is rejected; the balance turned over to spalling, a further continuation of the same work. Although the ragging is only a preparatory breaking, the ragger must pay attention not only to the separation of worthless rock, but also to a rough classification of concentrating, smelting and amalgamating ore, and accordingly he delivers two or more classes to textit{B. The Spatting.?The ore is broken by the spaller to still smaller pieces, of such size as may be required, for crushing of concentrating ore, and for cobbing of the separated ore. The spalling is performed by hammers of cast steel, of about two pounds weight, on long handles. The poor part, separated by spalling. is designed for crushing...