San Francisco Paper - Roasting and Leaching Concentrator Slimes Tailings (with Discussion)

THrough the courtesy of Dr. James Douglas I am permitted to give a summary of some of the results obtained in leaching slimes tailings in a series of experiments conducted under my direction at Douglas, Ariz., during the past year. While the test run for which the data are given deals with a particular case, much of the work is general in its application and may therefore be of interest. This work was done upon the ores of the Burro Mountain Copper CO. A description of the geology of the district will be found in the paper by R. E. Somers published in this volume, p. 604. The mineral is pyrite and chalcocite very finely disseminated throughout the gangue and a characteristic of all the ores is the large amount of alumina present. A representative analysis of the particular ore under consideration would be about as follows: Cu, per cent..................... 2.35 S, per cent...................... 3.0 Ag, ounces per ton.............. 0.05 CaO, per cent.................. 0.5 Au............................ None K2O, per cent.................... 4.0 Fe, per cent..................... 1.50 SiO², per cent.................... 70.0 Alz²O³, per cent....................13.OO The leaching of the ore direct was early dismissed from consideration for the following reasons: 1. The ore would have to be quite finely crushed to liberate the mineral for leaching; concentrating after crushing would cost but a few cents a ton; and a higher total reeovery would result from leaching tailings rather than ore. 2. Rough concentration would yield a suitable material for roasting to make sulphur dioxide or sulphuric acid in connection with the leaching scheme. 3. Such a program put the question of cost vs. recovery on a basis where flotation and discarding of tailings were directly comparable. Concentrating experiments already available indicated that the tail-