Neodymium nitric acid solutions, nitrate

After removing cerium (and thorium), the nitric acid solution of rare earths is treated with ammonium nitrate. Lanthanum forms the least soluble double salt with ammonium nitrate, which may be removed from tbe solution by repeated crystallization. Neodymium is recovered from this solution as the double magnesium nitrate by continued fractionation. 

Table IX. pH Electrode Measurements on Neodymium Nitrate—Nitric Acid Solutions at Constant Total Ionic Strength (I)...

The leach liquor is first treated with a DEHPA solution to extract the heavy lanthanides, leaving the light elements in the raffinate. The loaded reagent is then stripped first with l.Smoldm nitric acid to remove the elements from neodymium to terbium, followed by 6moldm acid to separate yttrium and remaining heavy elements. Ytterbium and lutetium are only partially removed hence, a final strip with stronger acid, as mentioned earlier, or with 10% alkali is required before organic phase recycle. The main product from this flow sheet was yttrium, and the yttrium nitrate product was further extracted with a quaternary amine to produce a 99.999% product. 

Belair, S., Labet, A., Mariet, C., Dannus, P. 2005. Modeling of the extraction of nitric acid and neodymium nitrate from aqueous solutions over a wide range of activities by CMPO. Solvent Extr. Ion Exch. 23 (4) 481 199. 

Nd2Ni04+5 powder was prepared by nitrate-citrate route as described by Courty, et a1. (1973). Stoichiometric amounts of neodymium and nickel oxides were dissolved in diluted nitric acid. After addition of a large excess of citric acid, the solution was dehydrated and heated until self-combustion of the precipitate to obtain submicronic precursor particles (Boehm, 2005). The final annealing was performed at 1000°C for 12 hours to obtain a single crystalline phase. The particles were then ball milled to obtain an average grain size (d0 5) of about 0.8 pm. A terpineol-based slurry was prepared from this powder and this was deposited on the electrolyte by screen printing and then sintered at 1100°C for three hours in air (Lalanne, 2008). 

Neodymium carrier 10 mg Nd3+/mL. Dissolve 6.38 g of Nd203 in a beaker with 10 mL of concentrated nitric acid heat if necessary. Transfer solution to flask and dilute to 250 mL with de-ionized water. If neodymium nitrate or neodymium chloride is available, the carrier may be prepared from one of these salts, with the weight of salt recalculated to match the chemical formula. 

In this chapter the thermodynamic analysis of the Nd(N03)3-HN03-H20 system is presented. The determination of the activity and the activity coefficient of the free neodymium (III) ion and the development of an accurate model for the activity behavior of aqueous binary electrolyte solutions consisting of the neodymium nitrate and nitric acid are presented. 

The liquid-liquid extraction feed solutions were prepared by dilution of the neodymium nitrate stock solution with distilled water and nitric acid. These then were contacted with equal volumes of 1M HDEHP in separatory funnels, agitated for. 5 hr by a mechanical shaker, allowed to separate for. 5 hr, shaken another. 5 hr, then allowed to settle for 12 hr before the phases were separated carefully. A volumetric sample of the organic phase was back-extracted four times with an equal volume of 6M HN03. This solution was evaporated to dryness in order to remove the excess acid and then diluted to an appropriate concentration. The pH of this solution was adjusted to 3.0 to eliminate any hydrolysis effects... 

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