Flotation of Barite from Mountain Pass Carbonatite Ore
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Authors
Penaloza Araujo, Isabel
Issue Date
2023
Type
Thesis
Language
Keywords
Barite , Critical Minerals , Froth flotation , Metallurgy , Reagents
Alternative Title
Abstract
Over the years, the demand for critical minerals has been increasing due to the evolution of technology and essential needs of the United States’ economy and climate change goals. Mountain Pass is the richest deposit of rare earth elements (REEs) in the US, and is the only active rare earth mining and processing site in North America. This deposit is described as a carbonatite type REE deposit, alkaline igneous rock constituted by bastnaesite the major REE ore, associated with primarily gangue minerals such as barite, calcite and quartz.Barite plays an essential role in oil and gas industry as a weighting material in drillings muds. However, the mineral is currently treated as gangue during the Mountain Pass rare earth oxides (REO) process. Barite is present at a 15 % (v/v) on the feed (cyclone overflow) of the flotation process. Therefore, separating barite from the ore not only presents the opportunities to improve rare earth oxides (REO) concentrate quality, but the opportunity to be recovered as a by-product. This study presents a preliminary investigation to explore possible routes for the recovery of barite prior to the flotation of REOs, providing information on improving the subsequent flotation process at Mountain Pass. Tests were conducted with the REO flotation feed ores, with sodium dodecyl sulfate (SDS) as a collector for recovering barite. The investigation also studied the effects of a commercial modifier (depressant), water glass (WG), on the depressing of the gangue minerals. The results have shown that a dosage of 200 g/Ton of SDS recovered more than 80% of the barite (i.e., reported as BaO due to the analytical method using X-ray fluorescence (XRF)) after performing a 20-minute flotation at pH 9. A 5-minute flotation was enough to recover at least 60% of BaO, which was considered to be the target recovery for the present project. However, the recovery for REO was 67% at the end of the 20 minutes and around 30% on the first 5 minutes of the flotation, which was significantly higher than the target set for the REO at 4%. The other gangue minerals were also recovered to the barite concentrate, with calcite (i.e., reported as CaO) around 51% and quartz (i.e., reported as SiO2) 39% at the end of the 20 minutes of the flotation. WG was used at different dosages to prevent the recovery of gangue minerals during barite flotation, which from literature review is known to depress certain alkaline salt-type minerals in the presence of SDS. With the addition of WG at different dosages 750 µL, 1 mL, 1.5 mL, and 3 mL, the results show that the lowest recovery obtained for barite was by using 3 mL of WG where the flotation achieved a 32% BaO recovery after 20 minutes of flotation. However, the recovery of the REO, calcite and quartz stayed at around 25%. Based on the preliminary study, recommendations for future research in barite flotation from Mountain Pass carbonatite ore are provided. The results have shown that a dosage of 200 g/Ton of SDS recovers more than 80% of the barite (i.e., BaO) after performing a 20 minutes flotation at pH 9. A 5-minute flotation is enough to recover at least 60% of BaO with the highest grade, which was considered the target recovery of barite for the present project. However, the recovery for REO is 67% at the end of the 20 minutes and around 30% on the first 5 minutes of the flotation, which was significantly higher than the target set for the REO at 4%. The other gangue minerals were also recovered to the concentrate, showing a recovery of calcite of 51% and quartz of 39% at the end of the 20 minutes of flotation. WG was used at different dosages to prevent the recovery of gangue minerals during barite flotation, which from literature review is known to depress certain alkaline salt-type minerals in the presence of SDS. With the addition of 750ul, 1 mL, 1.5 mL, and 3 mL of WG, the results show that the lowest recovery obtained for barite was by using 3 mL of WG where the flotation achieved a 32% BaO recovery after 20 minutes of flotation. However, the recovery of the REO, calcite and quartz stay at around 25%. Based on the preliminary study, recommendations for further research in barite flotation from Mountain Pass carbonatite ore is provided.