Testing new flotation reagents and process mineralogy study (ULiège)

Abstract

A laboratory-scale study was conducted with the purpose to replace a currently used secondary collector (promoter) at the Dundee Precious Metals Krumovgrad plant another that could achieve better flotation recovery of electrum and native gold from the ore. Different alternatives for secondary promoter coming from various suppliers have been tested to compare their performance with the reagent currently in use (Aero®238 Solvay) For the initial screening tests, 8 alternative promoters were compared based on concentrate mas pull and gold and silver grade and recovery. From these results, four promoters were selected to follow-up testing and more detail investigation using a factorial experimental design to find the optimal dosage and PAX/promoter ratio. Ultimately 3 promoters form the Hostaflot series from Clariant and one supplied by BASF have shown superior metallurgical performance than the basic combination. Physiochemical parameters (Eh, pH, DO and Temperature) have been monitored during the flotation tests to compare with the ones measured during the plant survey. Samples from the feed and tailings of the material have been submitted to automated mineralogy inspection to find out liberation degree of electrum grains, their morphology and chemical composition. Selected tailings from flotation have been also examined to find an explanation for gold lost during flotation. The performance of the promoters is discussed, and their dosage relationship with the concentrate mass pull, and the recoveries of Au, Ag and S.