Investigation of monazite processing by fluoride-sulfate method

Monazite is a valuable source of rare earth elements (REE), but the concentrate is not currently processed in Russia. This is due to the lack of effective and cost-effective technologies, as well as radioecological problems that arise during its processing. This paper considered a method for processing monazite in three stages: at the first stage, the concentrate is fluorinated with ammonium bifluoride (AB), and at the second stage, the products are sulfated with hydrofluorination products to convert low - soluble REE fluorides into the form of soluble sulfates. In the third stage, was studying the possibility of deep purification of silicon and phosphorus obtained by calcination. Thermogravimetric analysis of the process of sulfatization of the monazite concentrate hydrofluorination product was performed. As a result of the study, optimal conditions for fluoridation were identified. It is found that the sulfatization of the monazite fluorination product can be carried out in two stages: at temperatures of 280-300 °C with silicon distillation and at a temperature of more than 400 °C for deep purification.

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