Wendel Rodrigues, Wagner Silva, Pierre Fernandes, Pedro Gonzaga, and Ronaldo Fonseca, Clariant, describe how using a new reagent suite can reduce the negative effects of aluminosilicate minerals on gold flotation.
A
s a result of declining sulfide orebody quality, low grade and complex ores that were previously not economically feasible, such as transitional ores and former tailings, are now being considered for processing. The beneficiation of these ores is hindered by the presence of aluminosilicates – such as: kaolinite, chlorite, biotite, amphiboles, and montmorillonite. The various deleterious effects of aluminosilicates on flotation froth have been reported by numerous research studies, which show the aluminosilicate content influences on mining, operations, and processing of ores.1,2,3,4,5,6,7,8,9 Aluminosilicates affect mineral processing in grinding, froth flotation, thickening, dewatering, and in the final
disposal stages. The presence of aluminosilicates results in changes in slurry rheology. In flotation, aluminosilicates trigger a wide variety of problems, such as: increased reagent consumption by fine particles; low quality concentrate, due to silicate gangue entrainment; and recovery losses, possibly as a result of the formation of slime coating on air-bubbles or on mineral surfaces. In addition, aluminosilicate particles cause the flocculation phenomenon in the froth zone of flotation cells.4,10,11 On the other hand, gold and sulfide particles frequently occur as fine-grained inclusions (< 5 µm) in silicates, which do not present a satisfactory flotation performance with sulfhydryl collectors – such as xanthate, dithiophosphate,
global mining review // May/June 2021
53