International Journal of Mineral Processing, Vol.70, No.1-4, 67-82, 2003
Control of grinding conditions in the flotation of galena and its separation from pyrite
A specially designed mill which allowed the control of pH throughout grinding was used to study the effect of grinding conditions on galena flotation and galena separation from pyrite. The various reactions occurring on the mineral surface were investigated by a range of techniques, including OH(-) addition to maintain the grinding pH, ethlenediamine tetra acetic acid disodium salt (EDTA) extraction, X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements. Galena flotation and galena separation from pyrite were strongly dependent on the metal oxidation species produced on galena and pyrite surfaces under different grinding conditions. Iron oxidation species depressed both galena and pyrite flotation, while lead oxidation species activated pyrite but had little effect on galena. Optimum galena flotation and galena selectivity against pyrite were achieved by selecting grinding conditions that enabled lead and iron oxidation to be controlled. Aeration during grinding interfered with oxygen reduction occurring on the mineral acting as the cathode, as a result of galvanic interaction, and influenced the flotation of that cathodic mineral. Oxygen purging during grinding depressed galena flotation in single mineral experiments but increased galena selectivity against pyrite. (C) 2003 Elsevier Science B.V. All rights reserved.