Molten salt extraction

The pesticide industry generates many concentrated wastes that are considered hazardous wastes. These wastes must be detoxified, pretreated, or disposed of safely in approved facilities. Incineration is a common waste destruction method. Deep well injection is a common disposal method. Other technologies such as wet air oxidation, solvent extraction, molten-salt combustion, and microwave plasma destmction have been investigated for pesticide waste applications. 

Other potential technologies that can be applied to the treatment of concentrated wastes from pesticide manufacturing include wet air oxidation, solvent extraction, molten salt combustion, and microwave plasma destmction. 

The reactor is highly exothermic, and the data have been extracted as the molten salt being a hot stream. The basis of this is that it is assumed that the molten salt circuit is an essential feature of the reactor design. Thereafter, there is freedom within reason to choose how the molten salt is cooled. 

Figure 3 shows a flowsheet for plutonium processing at Rocky Flats. Impure plutonium metal is sent through a molten salt extraction (MSE) process to remove americium. The purified plutonium metal is sent to the foundry. Plutonium metal that does not meet foundry requirements is processed further, either through an aqueous or electrorefining process. The waste chloride salt from MSE is dissolved then the actinides are precipitated with carbonate and redissolved in 7f1 HN03 and finally, the plutonium is recovered by an anion exchange process. 

MSE Processing of High-Grade Plutonium Scrap. Americium is remove3 from plutonium in a liquid-liquid extraction process using molten salt (KC1, NaCl, MgCl2) and molten plutonium metal... 

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

Molten Salt Extraction. MSE has been used very successfully at Pocky Flats si nee 1967 to remove americium from plutonium ( 1, 2). 

Molten salt extraction residues are processed to recover plutonium by an aqueous precipitation process. The residues are dissolved in dilute HC1, the actinides are precipitated with potassium carbonate, and the precipitate redissolved in nitric acid (7M) to convert from a chloride to a nitrate system. The plutonium is then recovered from the 7M HNO3 by anion exchange and the effluent sent to waste or americium recovery. We are studying actinide (III) carbonate chemistry and looking at new... 

R. C. "Molten Salt Extraction of Americium from Molten Plutonium Metal," U.S. ERDA Rept. RFP-2365, Dow Chemical Co., Golden, Colorado, March 12, 1976. 

The following pages will describe several examples of pyrochemical processing as applied to the recycle of plutonium, and will briefly review the fundamental chemistry of these processes. We shall review the conversion of plutonium oxide to plutonium metal by the direct oxide reduction process (DOR),the removal of americium from metallic plutonium by molten salt extraction (MSE), and the purification of metallic... 

Early experimental work in electrorefining at Los Alamos by Mullins et-all ) demonstrated that americium could be partitioned between molten plutonium and a molten NaCl-KCl salt containing Pu+3 ions, and Knighton et-al(8), working at ANL on molten salt separation processes for fuel reprocessing, demonstrated that americium could be extracted from Mg-Zn-Pu-Am alloys with immiscible molten magnesium chloride salts. Work... 

Figure 10 shows in graphic form the utility of molten salt extractions for americium removal in one, two, and three stage extractions for various salt-to-metal extraction feeds. This graph demonstrates the impressive power of molten salt extraction systems for purification of plutonium from americium and related rare earth elements. 

The very chemically reactive plutonium hydride is usually decomposed in a vacuum-tight furnace capable of attaining a temperature of 700°C. Plutonium hydride that is decomposed under vacuum at temperatures below 400°C forms a very fine (<20y) metallic powder above 500°C the powder begins to sinter into a porous frit which melts at 640°C to form a consolidated metal ingot. This metal typically contains significant oxide slag but is suitable for feed to either molten salt extraction or electrorefining. 

Long, J.L. Perry, C.C. "The Molten Salt Extraction of Americium from Plutonium Metal", Nuc. Metal 15 p. 385 (1969). 

Knighton, J.B. Auge, R.G. Berry, J.W. "Molten Salt Extraction of Americium from Molten Plutonium Metal", Rocky Flats Plant report RFP-2365 (1976). 

Molten Salt Extraction. The metal from DOR and PuF4 reduction is impure and proceeds to the next step in the process sequence... 

Americium Extraction (more commonly referred to as Molten Salt Ex-or MSE). This process is specifically designed to reduce the americium content of the plutonium metal. (Am241 spontaneously grows into plutonium as a result of Pu241 decay.) When the impure metal contains more than 1000 ppm of americium, it is run through the MSE process. Otherwise, it bypasses the MSE step and proceeds directly to electrorefining. 

Molten Salt Extraction (MSE) - Salt Recovery. The salt residue from the americium extraction process is made up of NaCl, KC1, MgCl2, PuCl3, and AmCl3. A typical residue weighs approximately 2.0 kg and contains 200 g plutonium, 10-20 g americium, 50 g MgCl3 with the remaining equimolar NaCl-KCl. 

Molten Salt Extraction Salts Plutonium and Americium Recovery. We have demonstrated the ability to successfully strip the plutonium from the MSE salts. The resulting metal product now contains as much as 10% americium and as a result cannot be fed directly into the metal processing sequence. To use the plutonium we must remove the americium. 

Molten Salt Extraction and Electrorefining Salt Recycle. 

Chloride slagging process—See Molten salt extraction... 

See Molten salt extraction Slow neutron fission and isotopes... 

The alkali metals are the most violently reactive of all the metals. They are too easily oxidized to be found in the free state in nature and cannot be extracted from their compounds by ordinary chemical reducing agents. The pure metals are obtained by electrolysis of their molten salts, as in the electrolytic Downs process (Section 12.13) or, in the case of potassium, by exposing molten potassium chloride to sodium vapor ... 

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