Fused chloride salt process

However, since the LMFR offers such an excellent opportunity for the application of cheap pyrometallurgical processing, this path has been explored quite extensively. In this section a fused chloride salt process for the remoi al of fission poisons is described. In following sections a fluoride volatility process and a noble fi.ssion product removal process are described. 

Lithium. Several processes for lithium [7439-93-2], Li, metal production have been developed. The Downs cell with LiCl—KCl electrolyte produces lithium ia much the same manner as sodium is produced. Lithium metal or lithium—aluminum alloy can be produced from a mixture of fused chloride salts (108). Granular Li metal has been produced electrochemically from lithium salts ia organic solvents (109) (see LiTHlUM AND LITHIUM compounds). 

About 75 percent of the caustic produced is concentrated. The remainder is used directly as alkaline cell liquor—as, for example, in the conversion of propylene to propylene oxide by the chlorhydrin process. Similarly, there is some chlorine produced by methods that do not produce caustic, as shown in Table 12.18. Fused chloride salt electrolysis produces chlorine in the manufacture of magnesium metal by the Dow process, and of sodium metal in the Downs cell. The only other process of note is the Kel-Chlor process. This process converts by-product HCl to chlorine by oxidation with NO2 through the intermediates NOCl and HNSO5. 

As is pointed out in Chapter 20, the easiest blanket to handle in the LMFR would be a 10 w/o thorium-bismuthide slurry in bismuth. Chemical processing of this blanket would be very similar to the core processes already described. The major problem consists in transferring the bred uranium and protactinium from the solid thorium bismuthide to the liquid bismuth phase, so that they can then be chemically processed. Two examples of proposed processes are shown in Fig. 22-11, which shows a process that can be used with the fused chloride salt FPS removal process, and in Fig. 24-19, which shows a flowsheet for a process to be used with the fluoride volatility process. 

The electrolysis Of fused alkali salts.—Many attempts have been made to prepare sodium directly by the electrolysis of the fused chloride, since that salt is by far the most abundant and the cheapest source of the metal. The high fusion temp. the strongly corrosive action of the molten chloride and the difficulty of separating the anodic and cathodic products, are the main difficulties which have been encountered in the production of sodium by the electrolysis of fused sodium chloride. Attention has been previously directed to C. E. Acker s process for the preparation of sodium, or rather a sodium-lead alloy, by the electrolysis of fused sodium chloride whereby sodium is produced at one electrode, and chlorine at the other but the process does not appear to have been commercially successful. In E. A. Ashcroft s abandoned process the fused chloride is electrolyzed in a double cell with a carbon anode, and a molten lead cathode. The molten lead-sodium alloy was transported to a second chamber, where it was made the anode in a bath of molten sodium hydroxide whereby sodium was deposited at the cathode. A. Matthiessen 12 electrolyzed a mixture of sodium chloride with half its weight of calcium chloride the addition of the chloride of the alkaline earth, said L. Grabau, hinders the formation of a subchloride. J. Stoerck recommended the addition of... 

Process control of fused chloride process. The object of the process described above is to remove 59 g of fission-product Zr and 238 g of FPS from the fuel per day, at the same time losing only 2 g of U. For this, careful control of the process is required. Continuous measurement of the U concentrations in the salt streams from columns 1 and 2 will be required. The U concentrations in these streams are good indicators of column operation, i.e., if the U concentrations are correct, those of the Zr and FPS should also be correct. Assuming constancy of fuel composition and all flow rates, the two operating variables affecting the process are. 

The energy will be divided about equally between beta and gamma radiation. For this fused chloride process, the heat release will, of course, depend on the poison concentrations, but will probably range from 100,000 to 500,000 Btu/(hr)(ft of salt). 

It was an adaptation of the Castner cell to sodium chloride for fused caustic electrolysis. A mixture of sodium chloride and other chlorides, molten at 620°C, was electroly2ed ia rectangular or oval cells heated only by the current. Several cells have been patented for the electrolysis of fused salt ia cells with molten lead cathodes (65). However, it is difficult to separate the lead from the sodium (see Electrochemical processing). 

Electrolytic Processes. The electrolytic procedures for both electrowinning and electrorefining beryUium have primarily involved electrolysis of the beryUium chloride [7787-47-5], BeCl2, in a variety of fused-salt baths. The chloride readUy hydrolyzes making the use of dry methods mandatory for its preparation (see Beryllium compounds). For both ecological and economic reasons there is no electrolyticaUy derived beryUium avaUable in the market-place. 

The first production of aluminum was by the chemical reduction of aluminum chloride with sodium. The electrolytic process, based on the fused salt electrolysis of alumina dissolved in cryolite, was independently developed in 1886 by C. M. Hall in America and P. L. Heroult in France. Soon afterwards a chemical process for producing pure alumina from bauxite, the commercial source of aluminum, was developed by Bayer and this led to the commercial production of aluminum by a combination of the Bayer and the Hall-Heroult processes. At present this is the main method which supplies all the world s needs in primary aluminum. However, a few other processes also have been developed for the production of the metal. On account of problems still waiting to be solved none of these alternative methods has seen commercial exploitation. 

Electrolysis processes have been known since Davy first isolated the metal in 1807. Electrolysis, however, suffers from certain disadvantages. A major problem involves miscibility of the metal with its fused salts. Because of this molten potassium chloride, unlike sodium chloride, cannot be used to produce the metal. Fused mixtures of potassium hydroxide and potassium carbonate... 

The general methods for the production of the alkali metals are (1) Electrolytic processes involving the electrolysis of (a) the fused hydroxide, or (b) a fused salt— chloride, nitrate, cyanide, etc. (2) Chemical processes involving the reduction of hydroxide, or carbonate, or other salt with carbon, metal carbide, iron, calcium, magnesium, aluminium, etc. W. Spring 5 claims to have reduced a little potassium chloride by passing hydrogen over the salt at a red heat. 

---