An Investigation Into Hydroxamic Acid and Amine Collectors for Enhanced Pyrochlore Flotation Efficiency
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Authors
Berin-Costain, Petra Linnea
Date
2024-09-05
Type
thesis
Language
eng
Keyword
Flotation , Hydroxamic acid , Niobium , Pyrochlore , Amine , Flotation reagent
Alternative Title
Abstract
Current large-scale niobium mineral beneficiation processes upgrade ores with a narrow range of mineralogical characteristics. These flowsheets are related by their use of cationic amine collectors to selectively float the niobium-bearing mineral pyrochlore under acidic conditions. Not only are niobium losses high due to the number of stages, but such processes are also not easily applied to finely disseminated, low grade ores. Hydroxamic acid (HA) collectors have been studied as part of a growing body of work on alternative pyrochlore beneficiation methods due to their resistance to slimes, strong transition metal chelation mechanisms, and ability to float pyrochlore at neutral pH. However, the high reagent doses reported in the literature have prevented HA collectors from seeing application in large scale operations. This work addresses the need for process development specific to finely disseminated pyrochlore bearing ores, which are currently considered untenable for upgrading. In this study, the effects of collector dissolution, air flow, pulp density, and HA dosage on rougher flotation performance were investigated. A concentrate with a grade of 6.1 % Nb2O5 and 94.5% niobium recovery was achieved from a single rougher flotation stage with a benzohydroxamic (BHA) acid collector. Furthermore, the BHA dosage was reduced from 5400 g/t to 2300 g/t with an increase in pulp density. It was found that BHA dosage could be further reduced to 1572 g/t with the addition of a cleaner stage, producing a concentrate grade of 7.8 % Nb2O5 with 84.5% niobium recovery. An amine cleaner flotation stage was studied to upgrade the rougher concentrate produced using BHA. For pyrochlore promotion, the pH needed to be lowered from 7.5 to 1.5. Despite the bulk gangue rejection in the rougher stage and a hydrochloric acid leach, the amine flotation suffered from significant buffering due to the presence of residual reactive calcites. Finally, a Central Composite Design was employed to model the effects of hydroxamic acid dosage, pulp density, and transformer oil dosage on Nb2O5 grade and recovery. The model, paired with UV visible spectroscopy analysis of the pulp filtrate has contributed to understanding hydroxamic acid’s potential to upgrade ores previously considered untenable.
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.