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- Alemrajabi, Mahmood, 1989-, et al.
(författare)
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Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer
- 2016
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Ingår i: IMPC 2016 - 28th International Mineral Processing Congress. - : Canadian Institute of Mining, Metallurgy and Petroleum. - 9781926872292
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Konferensbidrag (refereegranskat)abstract
- In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate.
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| 2. |
- Alemrajabi, Mahmood, 1989-, et al.
(författare)
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Processing of a rare earth phosphate concentrate obtained in the nitrophosphate process of fertilizer production
- 2019
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Ingår i: Hydrometallurgy. - : Elsevier. - 0304-386X .- 1879-1158. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- In this study, different processes have been developed and applied to treat a rare earth phosphate concentrate obtained within the nitrophosphate process of fertilizer production. Methods to remove impurities such as Fe and Ca have been investigated as well as to separate the phosphorous and thereby facilitate dissolution of the rare earth elements (REE). These methods include thermal treatment with sodium hydroxide and sodium double sulphate precipitation with and without alkaline conversion, followed by selective dissolution in different acids. The proposed processes were compared and analyzed from the perspective of introducing an appropriate intermediate product for further individual REE separation. The results have shown that after thermal treatment with NaOH at 400 °C, the phosphorous can be removed from the rare earth phosphate concentrate by water leaching. Investigation of different REE phosphate concentrates demonstrated that mixed Ca and REE phases, e.g. REEmCan(PO4)3m+2n/3 and CaHPO4 are less likely to dephosphorize than REE(PO4).nH2O and FePO4.H2O under these conditions. The recovery of REE to a mild acidic solution is limited by the presence of remaining phosphate ions and by the formation of REE oxide phases during the thermal treatment. The results also show that a solution containing 40 g/L REE; free of phosphorous, calcium and iron can be obtained after reprecipitation of the rare earth phosphate concentrate as sodium rare earth double sulphates followed by alkaline conversion with sodium hydroxide and dissolution in nitric acid.
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| 3. |
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| 4. |
- Alemrajabi, Mahmood, 1989-
(författare)
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Recovery of Rare Earth Elements from an Apatite Concentrate
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rare earth elements (REE) are a group of 17 elements including lanthanides, yttrium and scandium; which are found in a variety of classes of minerals worldwide. The criticality of the application, lack of high grade and economically feasible REE resources and a monopolistic supply situation has raised significant attention in recovery of these metals from low grade ores and waste materials. In this thesis, the recovery of REE from an apatite concentrate, containing 0.5 mass% of REE, within the nitrophosphate route of fertilizer production has been investigated. Most of the REE (≥ 95%) content can be recovered into a phosphate precipitate with almost 30 mass% REE. Different processes have been developed to convert the REE phosphate precipitate into a more soluble form to obtain a solution suitable for further REE purification and individual separation. It has been shown that after reprecipitation of the REE phosphate concentrate as REE sodium double sulphate and then transformation into a REE hydroxide concentrate, a solution containing 45g/L REE free of Ca, Fe and P can be obtained. The results suggest that the apatite waste after processing of iron ore have the potential to be a very important source for REE in Europe and that the economy is strongly supported by the simultaneous extraction of phosphorous.The potential of using hollow fiber supported liquid membrane (HFSLM) extraction in individual and group separation of REE has been investigated. A hollow fiber supported liquid membrane plant in pilot scale has been operated according to the three main configurations: standard hollow fiber supported liquid membrane technology (HFSLM); hollow fiber renewal liquid membrane technology (HFRSLM) and emulsion pertraction technology (EPT). The standard HFSLM operation is more selective than HFRSLM and EPT, while higher metal transport rate is observed in EPT followed by HFRSLM and HFSLM. The HFRLM configuration helps to maintain the performance of the liquid membrane.
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| 5. |
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| 6. |
- Alemrajabi, Mahmood, 1989-, et al.
(författare)
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Separation of Rare-Earth Elements Using Supported Liquid Membrane Extraction in Pilot Scale
- 2022
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045.
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Tidskriftsartikel (refereegranskat)abstract
- The use of supported liquid membrane extraction for recovery and separation of rare-earth elements (REEs) has been investigated. Experiments have been carried out using the different configurations: (1) standard hollow fiber supported liquid membrane operation (HFSLM), (2) renewal liquid membrane operation (HFRLM), and (3) emulsion pertraction technology (EPT). The experiments were performed in pilot scale using a hollow fiber module with a mass transfer surface area of 8 m2. Synthetic feed solution was used with compositions based on a process for recovery of REE from an apatite concentrate. The total concentration of REE in the feed was varied from 1 to 22 mM REE and the pH was varied in the range 1.5–3.2. Di(2-ethylhexyl) phosphoric acid (D2HEPA) diluted in kerosene, 10% (v/v), was used as the organic membrane solution, and 3 M HCl was used as stripping solution. In supported liquid membrane extraction, the extraction performance is governed by both the kinetics of REE transport through the membrane and by thermodynamics. The effect of feed composition on the selectivity and transport of REE through the liquid membrane have been investigated. The results show that the liquid membrane is more selective toward the heavy REE at lower pH values and higher REE concentration. HFRLM shows a higher transport rate than HFSLM, while the HFSLM configuration gives a higher selectivity toward individual REE. The membrane performance in HFSLM configuration rapidly decays with time, while in the HFRLM and EPT configurations, the performance is much more stable. Possible mechanisms for decaying membrane performance are discussed, and gel formation is identified as being of significant importance. Gel formation is observed at an organic loading above ∼46% for Nd, 38% for Y, 46% for Dy, and 65% for Er. The work performed in this study serves as an initial step to demonstrate that HFRLM and EPT can provide stable operation and be feasible options for processing of REE liquors. A process flow diagram for the recovery of the REE, present in the apatite concentrate, in three fractions is proposed based on the results from this study.
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| 7. |
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| 8. |
- Korkmaz, Kivanc, et al.
(författare)
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Separation of Valuable Elements from NiMH Battery Leach Liquor via Antisolvent Precipitation
- 2020
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 234
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth elements (REE) have been selectively recovered from NiMH battery leach liquors by antisolvent precipitation. The active anode material was leached using sulfuric acid. The REE were then separated from the other elements by precipitation as sulfates after addition of either ethanol or 2-propanol (antisolvent). In a second step, Ni and Co are separated as sulfates by the same technique. The concentration of elements in different acid alcohol mixtures at 25 degrees C and -10 degrees C respectively are presented as a function of time after addition of the alcohol, and the optimum conditions for separation of the REE in pure form are presented. Under optimum conditions, 5.6 mol/L (Organic/Aqueous (O/A) volumetric ratio = 0.7) of 2-propanol at 25 degrees C, 82% of the REE have precipitated 3 h after addition of the antisolvent and the purity is 99.9%.
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| 9. |
- Korkmaz, Kivanc, et al.
(författare)
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Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel-Metal Hydride HEV Batteries
- 2018
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 8:12, s. 1062-
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the recovery of valuable metals from a Panasonic Prismatic Module 6.5 Ah NiMH 7.2 V plastic casing hybrid electric vehicle (HEV) battery has been investigated, processing the anode and cathode electrodes separately. The study focuses on the recovery of the most valuable compounds, i.e., nickel, cobalt and rare earth elements (REE). Most of the REE (La, Ce, Nd, Pr and Y) were found in the anode active material (33% by mass), whereas only a small amount of Y was found in the cathode material. The electrodes were leached in sulfuric acid and in hydrochloric acid, respectively, under different conditions. The results indicated that the dissolution kinetics of nickel could be slow as a result of slow dissolution kinetics of nickel oxide. At leaching in sulfuric acid, light rare earths were found to reprecipitate increasingly with increasing temperature and sulfuric acid concentration. Following the leaching, the separation of REE from the sulfuric acid leach liquor by precipitation as NaREE (SO4)(2)center dot H2O and from the hydrochloric acid leach solution as REE2 (C2O4)(3)center dot xH(2)O were investigated. By adding sodium ions, the REE could be precipitated as NaREE (SO4)2 center dot H2O with little loss of Co and Ni. By using a stoichiometric oxalic acid excess of 300%, the REE could be precipitated as oxalates while avoiding nickel and cobalt co-precipitation. By using nanofiltration it was possible to recover hydrochloric acid after leaching the anode material.
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