Bismuth phosphate

The first successflil production method for the separation of Pu from U and its fission products was the bismuth phosphate process, based on the carrying of Pu by a precipitate of BiPO (126). That process has been superseded by Hquid-Hquid extraction (qv) and ion exchange (qv). In the Hquid-Hquid... 

Metaphosphoric acid may also be used it hydrolyses in warm acid solution forming phosphoric(V) acid. Thus bismuth may be precipitated as bismuth phosphate in a dense, crystalline form. 

Saturday, December 19, 1942. Today Thompson tested the use of bismuth phosphate as a carrier for 94 in its reduced state with rather encouraging results. Upon precipitating relatively high concentrations of bismuth (15-25 mg per 10 cc) as bismuth phosphate from 20% UNH solution, he finds the 94 to be carried to the extent of more than 85%. The bismuth phosphate precipitates are slow in forming and require digestion at temperatures of the order of 75°C. 

He finds that the bismuth phosphate precipitate is very dense and crystalline, which are desirable properties, and dissolves readily in HC1. 

In view of Thompson s results on the carrying of Pu+I by bismuth phosphate, Cunningham and Werner made an immediate test today to see whether it is carried at a ratio of Bi+3 Pu+1 of about 100 1. Their results indicate that under conditions similar to those of Thompson s experiment, the Pu+I> is carried to the extent of 98%. This was fast work and illustrates the pace at which our group is now working. They also made a test of the carrying of Pu+I> by hafnium phosphate at a ratio of Hf Pu of 100 1 and they find that about 90% of the Pu is carried. 

The reason for the ultramicrochemical test was to establish whether the bismuth phosphate would carry the plutonium at the concentrations that would exist at the Hanford extraction plant. This test was necessary because it did not seem logical that tripositive bismuth should be so efficient in carrying tetrapositive plutonium. In subsequent months there was much skepticism on this point and the ultramicrochemists were forced to make repeated tests to prove this point. Thompson soon showed that Pu(Vl) was not carried by bismuth phosphate, thus establishing that an oxidation-reduction cycle would be feasible. All the various parts of the bismuth-phosphate oxidation-reduction procedure, bulk reduction via cross-over to a rare earth fluoride oxidation-reduction step and final isolation by precipitation of plutonium (IV) peroxide were tested at the Hanford concentrations of... 

Irradiated Fuel A historically important and continuing mission at the Hanford site is to chemically process irradiated reactor fuel to recover and purify weapons-grade plutonium. Over the last 40 years, or so, several processes and plants— Bismuth Phosphate, REDOX, and PUREX—have been operated to accomplish this mission. Presently, only the Hanford PUREX Plant is operational, and although it has not been operated since the fall of 1972, it is scheduled to start up in the early 1980 s to process stored and currently produced Hanford -Reactor fuel. Of nine plutonium-production reactors built at the Hanford site, only the N-Reactor is still operating. 

The original method of phosphate preparation involved extracting the phosphate and reprecipitating it as a bismuth phosphate (Tudge 1960). Alternatively, it is precipitated as a silver phosphate (Wright and Hoering 1989) which involves fewer steps and, more importantly, silver phosphate is not hygroscopic (as is bismuth phosphate) which minimizes the potential for contamination by atmospheric water. 

Many other heterogeneous electrodes have been developed based on, e.g., calcium oxalate or stearate in paraffin, barium sulphate in paraffin or silicone-rubber, bismuth phosphate or iron(III) phosphate in silicone-rubber, caesium dodecamolybdophosphate in silicone-rubber and amminenickel nitrate in phenol-formaldehyde resin39 these permit the determination, respectively, of Ca and oxalate, Ba and sulphate, Bi or Fe(HI) and phosphate, Cs, Ni and nitrate, etc. 

Bismuthonium ylides, 4 34 Bismuth(III) oxide, 4 23-24 Bismuth oxide(l l), 4 23 Bismuth oxide(l 2), 4 23 Bismuth oxide(2 4), 4 23 Bismuth oxide(3 5), 4 23 Bismuth oxide(4 9), 4 23 Bismuth oxide halides, 4 23 Bismuth oxides, 4 23-24 Bismuth oxybromide, 4 23 Bismuth oxychloride, 4 23 physical properties of, 4 20t pigment used in makeups, 7 836t Bismuth oxyfluoride, 4 23 Bismuth oxyiodide, 4 23 Bismuth pentafluoride, 4 22 physical properties of, 4 20t Bismuth phosphate, 4 25... 

Crystal phases that contain phosphorus in addition to bismuth and molybdenum are not known. Phosphorus is probably present as bismuth phosphate. Remarkably, however, a fresh commercial catalyst seems to contain only a minor amount of the a-phase in spite of the Bi/Mo ratio which is close to 2/3 (Schuit [81]). 

Bismuth phosphates and various other bismuth salts (e.g. arsenate, basic sulfate, and titanate) are capable of producing benzene, as reported by Seiyama et al. [283]. A selectivity of 49% is reached with a combination 2Bi203 P205 at 500°C. Sakamoto etal. [271] varied the Bi/P ratio and stated that a 2/1 ratio gives the maximum selectivity. 

Bismuth phosphate has been investigated as a catalyst for aromatization of the four different butene isomers at 550°C. An optimal catalyst has an atomic ratio Bi/P = 2 (Sakamoto et al. [271]). Isobutene is converted at short contact times (r 0.3 sec) to dimers and to aromatics, with a selectivity of 29% each. n-Butenes give much lower yields. 

The oldest, most well-established chemical separation technique is precipitation. Because the amount of the radionuclide present may be very small, carriers are frequently used. The carrier is added in macroscopic quantities and ensures the radioactive species will be part of a kinetic and thermodynamic equilibrium system. Recovery of the carrier also serves as a measure of the yield of the separation. It is important that there is an isotopic exchange between the carrier and the radionuclide. There is the related phenomenon of co-precipitation wherein the radionuclide is incorporated into or adsorbed on the surface of a precipitate that does not involve an isotope of the radionuclide or isomorphously replaces one of the elements in the precipitate. Examples of this behavior are the sorption of radionuclides by Fe(OH)3 or the co-precipitation of the actinides with LaF3. Separation by precipitation is largely restricted to laboratory procedures and apart from the bismuth phosphate process used in World War II to purify Pu, has little commercial application. 

B. Pelletier,24 and C. M. Marx found that molten bismuth dissolves a little phosphorus, and W. Heintz, that when bismuth phosphate is heated in a current... 

Disodium hydrogen phosphate white, crystalline precipitate of bismuth phosphate ... 

In the first separation procedure operated in a technical scale, was separated as Pu(IV) from U and fission products by coprecipitation with BiP04 (bismuth phosphate process). Today, solvent extraction is applied, because it leads to higher decontamination factors and can be operated as a continuous process. 

The discovery of nuclear fission in 1938 proved the next driver in the development of coordination chemistry. Uranium-235 and plutonium-239 both undergo fission with slow neutrons, and can support neutron chain reactions, making them suitable for weaponization in the context of the Manhattan project. This rapidly drove the development of large-scale separation chemistry, as methods were developed to separate and purify these elements. While the first recovery processes employed precipitation methods (e.g., the bismuth phosphate cycle for plutonium isolation). 

Thompson, S.G. Seaborg, G.L. The first use of bismuth phosphate for separating plutonium from uranium and fission products. Prog. Nucl. Energy Ser. 3 1956, 1, 163. 

Traces of thorium have been co-precipitated from strongly acidic medium with barium sulphate [6]. After isolation with bismuth phosphate, thorium can be leached from the precipitate with (NH4)2C03 solution [7]. 

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