Recovery of rare earth elements from El-Sela effluent solutions

Abstract

Available online xxxKeywords: Rare earthsAmmonium hydroxide Uraniferous Hydrofluoric acid Oxalic acid a b s t r a c tThe study area of Gabal El Sela at Halaib environ is located at about 20 km west of Abu Ramad City, Egypt. An uraniferous ore material associated with REE was subjected to sulphuric acid leaching for the extraction of uranium mainly and REEs as a by-product.93.9% of U and 60% of REEs content were leached using À0.5 mm ground ore with 100 g/l sulfuric acid, acid/ore ratio of 2.0 and agitate for 6 h at 40 C. After uranium extraction, effluent solutions containing 135 ppm rare earths were treated with 30% ammonium hydroxide to pH of 9.3 to enhance the rare earth elements concentration. The precipitated cake was filtered then dried at 110 C. The dried cake containing 16.2% rare earth elements was dissolved by hydrochloric acid at pH 1.0. The rare earths precipitated cakes of 36.9, 45.7 and 48.7% REEs were recovered successfully from the chloride leach liquor of 900 ppm rare earths by using 5% v/v from 50% HF, 6% wt/v oxalic acid and 4.8% wt/v oxalic acid to chloride solution with heating for one hour which respectively. 73.5% REEs precipitated cake was achieved by double precipitation, firstly by hydrofluoric acid followed by oxalic acid precipitation.

Characteristics of Precipitation of Rare Earth Elements with Various Precipitants

“…In Figure 4a, the concentration of free REEs in solution in equilibrium with Re-sulfate precipitates is shown. In the construction of this figure, Equations (12) and (13) were used. Equation 12was used for pH 6 and 4, while Equation (13) was used for pH 2 and 1.…”

“…In addition, at pH 4, on the other hand, the concentration of sulfate ion is 2 × 10 −4 M, because of the added sulfate plus sulfate provided by sulfuric acid to adjust the pH of the solution. The same is also applicable for Figure 4d, in which case, Equations (14) and (15) were used instead of Equations (12) and (13).…”

“…Such pretreated ores are then subjected to the leaching process of REEs. The leach liquor is frequently subjected to the removal of impurities such as iron, calcium, uranium, and thorium by going through stage-wise precipitation using various compounds such as hydroxide, carbonate, sulfate, and oxalate [7][8][9][10][11][12][13]. After the removal of these impurities by chemical precipitation, REEs in solution are then subjected to precipitation using various precipitants, which in general takes place at pH above 3−4, since most of these impurities are precipitated at around these pHs.…”

Selection of an appropriate leaching method for light REEs from Esfordi flotation concentrate based on mineral characterization

“…IV). This could be attributed to the complexation of REEs with fluoride (Krishnamurthy and Gupta, 2004;Khawassek et al, 2015). Monazite-xenotime is not attacked by HNO 3 or HCl at low temperatures (Jordens, Cheng, and Waters, 2013).…”

Recovery of Neodymium as (Na, Nd)(SO4)2 from the Ferrous Fraction of a General WEEE Shredder Stream

“…The Na can be provided by either NaOH or Na 2 SO 4 . This precipitation reaction offers an alternative to the traditional oxalate precipitation, which is more expensive [17].…”