Abstract
Abstract Rare earth (RE) and iron minerals in tailings exhibit fine embedded granularity and are closely associated with silicates, carbonates, and other lode minerals, which are difficult to be recycled. Studies of these tailings led to some new processes of ore dressing, involving grinding, RE flotation, strong magnetic separation, and positive iron flotation. In this closed circuit process, RE and iron minerals were separated after grinding, and the materials resulted from the flotation of small-sized RE and iron mineral particles were accurately controlled using a combination of inhibitors, dispersants, pH regulators, and collector agents. The ore dressing were ground to a fineness of 0.045 mm, which was a process accounting for 95.6% of the material. The amount of water glass, NXJ (a combination of sodium carbonate mixed with a fine mud dispersant), and BGH (hydroxamic acid collector, a combination of 3-carboxy-2-naphthylhydroxamic acid and C5-9 hydroxamic acid) used in the primary separation of RE were 2.4 kg/t, 2.5 kg/t, and 2.4 kg/t, respectively. The dosages of ammonium fluorosilicate and GXY (fatty acid collector, a combination of sodium oleate mixed with oxidized paraffin soap) used with iron coarse were 2.2 kg/t and 1.2 kg/t, respectively. The RE collectors achieved chemical separation of Ce, La, and other particles and formed stable five-membered cyclic chelates. Consequently, through the closed circuit experiment, the RE grade and recovery rate in the RE concentrate were improved to 50.3 and 61.6%, respectively. The total iron (TFe) grade and recovery rate in the TFe concentrate were improved to 64.0 and 30.0%, respectively, and other useful metals were also enriched; this process managed secondary recycling of RE and TFe possible, leading to improvements in resource utilization.
Highlights
Rare earth (RE) and iron minerals in tailings exhibit fine embedded granularity and are closely associated with silicates, carbonates, and other lode minerals, which are difficult to be recycled. Studies of these tailings led to some new processes of ore dressing, involving grinding, rare earth (RE) flotation, strong magnetic separation, and positive iron flotation
The Bayan Obo mine is a large-scale deposit mainly consisting of iron ore and rare earth (RE), and the quantity of its RE reserves ranks first in the world
The rare earth oxide accounted for 55.8% in the bastnaesite, while the rare earth oxide accounted for 44.2% in monazite
Summary
The Bayan Obo mine is a large-scale deposit mainly consisting of iron ore and rare earth (RE), and the quantity of its RE reserves ranks first in the world. Because of the applications of stage grinding and magnetic separation processes to iron ore dressings, the size distribution in the tailings is relatively large; this increases the difficulty in RE recovery. The RE in iron ore tailings is recycled with flotation processes using combinations of inhibitors such as water glass and 8# (Naphthalene hydroxamic acid) RE collector. Since it has been approved for production processes, the recovery rate for RE using this process is very low, and it is ineffective for recycling RE minerals found as fine particles. This study focuses on the processes for dressing RE tailings, the use of effective reagent regimens, the comprehensive recycling of RE and TFe, and the development of critical technical processes for effective utilization of fine grain, complex, and secondary RE and TFe resources
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