Modern Copper Smelting Volume 7 (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. THE SAMPLING AND ASSAYING OF COPPER. The first step usually taken in the treatment of an ore of copper is to learn its value by determining the proportion of that metal that it contains. This process is called assaying, as distinguished from chemical analysis, which includes the further investigation as to the general composition of the ore. We shall confine our discussion in this place to assaying only. The assaying of any given parcel of ore is necessarily preceded by the process of sampling, by which we seek to obtain, within the compass of a few ounces, a correct representative of the entire quantity of ore, which may vary in amount from a few pounds to several thousand tons. With rich ores, it will lessen the chance of serious error in large transactions to divide the lot into parcels, of not over fifty tons each, and sample each of these lots by itself. The utmost care and vigilance in sampling and assaying should be required at every smelting works, both in the interest of the works and in that of the ore-seller. American conditions have encouraged the use of automatic devices for the sampling of ores and mattes, and although there is still a certain prejudice against them in some private works, I believe that they have been adopted by all public sampling works of any standing. Such works are constantly handling large quantities of rich and very varied material, and it is a matter of absolute necessity to them that their methods of sampling should be above suspicion, and free from the factor of "personal equation" that would be introduced by the employment of a reasoning agent to take the sample. Automatic samplers, constructed on correct principles, must necessarily attain absolute accuracy, and a sufficiently extended comparison of their ...