Mineral Beneficiation - Radiotracer Studies of the Action of Dithiophosphate in the Selective Flotation of Galena and Sphalerite Using CuS04 and NaCN

DITHIOPHOSPHATE collectors are commonly used in the flotation of sulphide minerals. Studies of the interaction of a typical dithiophosphate collector with galena surfaces have been previously reported from these laboratories.'* These fundamental studies were carried out by employing phosphorus labeled radioactive dithiophosphate. Radioactivity determinations then could be used to measure readily and accurately the small concentrations of dithiophosphate that are present under conditions of flotation processes. Measurements were made on ground mineral, determining the amount sorbed indirectly from the concentrations in solution; and studies were also made with single crystals, determining the amount sorbed directly by counting the crystal surface. The rates, isotherms and reversibility characteristics of dithiophosphate sorption, the competition between phosphate and dithiophosphate for the mineral surface, and the exchange of sorbed dithiophosphate with dissolved dithiophosphate were studied. These studies have now been extended by sorption measurements in flotations with a Fagergren machine. For this work, the selective flotation of galena and sphalerite from quartz was chosen, using ammonium di-(sec-butyl) dithiophosphate as the collector, sodium cyanide as depressant for sphalerite, and copper sulphate as an activator for sphalerite. While the selective flotation of galena and sphalerite using a single dithiophosphate collector is not typical of flotation practice (two different collectors are generally used), it was found that a reasonably good separation could be obtained by using zinc sulphate with the sodium cyanide in the galena flotation and by cleaning the sphalerite concentrate or by carrying out the sphalerite flotation in an alkaline medium. Data of practical importance on the distribution of collector between the concentrates, tailings, and solutions were obtained, particularly with regard to the effect of copper sulphate and sodium cyanide. In addition to the selective flotation of galena and sphalerite from quartz, single flotations of galena-quartz and sphalerite-quartz mixtures were carried out, along with blank flotations on quartz alone. The present paper describes the results of these experiments. As in previous papers, the term sorption is used to designate uptake of collector by the mineral, without implication as to the nature of the processes involved. Experimental Materials: The mineral system was a ground synthetic mixture of galena, sphalerite, and quartz. The galena was from Galena, Kans., and contained 75 pct lead (theoretical 85.6 pct Pb for PbS); the sphalerite, from Ottowa County, Okla., contained 63 pct zinc (theoretical 67.2 pct Zn for ZnS); and the quartz from Klondike, Mo., analyzed as 99.97 pct SiO,. Sulphur labeled radioactive di-(sec-butyl) dithiophosphate was prepared from SS supplied by the Oak Ridge National Laboratory on allocation from the U. S. Atomic Energy Commission. The synthesis consisted of precipitating barium sulphate, reducing the barium sulphate to barium sulphide, acidifying to form hydrogen sulphide, and oxidizing the hydrogen sulphide with iodine to elemental sulphur.