Kinetic modelling and optimization of flotation process of electrum

The investigation of flotation as an alternative method to cyanide leaching of gold ores is significant in terms of economic and environmental aspects. In this study, a gold ore sample containing 4.79 ppm Au and 7.72 ppm Ag was used. Gold and silver were observed to be present as liberated electrum or associated with or within quartz, galena, and sphalerite. Initially, five-stage rougher flotation tests were conducted, and then three-stage scavenger circuits and four-stage cleaning flotation circuits were performed in order to obtain high-content gold concentrate and decrease losses of Au and Ag in tailings. As a result of tests, the flotation concentrate assayed as 437 ppm Au and 511 ppm Ag was obtained with recoveries of 76.3% and 58.5%, respectively. This study reveals that the concentrates ready for direct smelting without any additional process can be obtained with flotation. In order to determine kinetic characteristic of electrum in the sample, the tests were conducted using first-order model, first-order model with rectangular distribution of rate constants, second-order model and second-order model with rectangular distribution of rate constant. The second-order model was considered as most reasonable for fitting the recoveries of gold as a function of flotation time during the flotation process.