New York City Paper - Combined Amalgamation and Concentration of Silver-Ores

It is well known that many so-called free-milling silver arcs are so classed more from their value necessitating a cheap process than from a real adaptability to raw amalgamation. Such low--grade ores, carrying more or less sulphurets, are more profitably treated by a cheap rapid process than by the more effective but costly process of roasting arid amalgamation. The tailings are sometimes crudely concentrated, or, after lying and becoming partially oxidized, are again worked in pans. Of late years, by the use of improved methods of concentration, many old low-grade tailings-piles have been reworked to a good profit; and in some improved mills arrangements are made to concentrate before or after amalgamation, thus making a single treatment in mill suffice. It is self-evident that on a low-grade ore a small increase in percentage saved is of no commercial advantage if accompanied by a material increase in cost, and therefore a cheap and continuous system of work is the real necessity, if a fair saving be effected. As an illustration of the possibilities of combined concentration and amalgamation on some ores, the following results of a working test at the New York Ore-Milling and Testing Works will be of some interest. The ore treated was a hard white quartz from Mexico, carrying a very small percentage of finely divided sulphurets, chiefly iron