Mixed Chloride

Another method of purifying niobium is by distillation of the anhydrous mixed chlorides (29). Niobium and tantalum pentachlorides boil within about 15°C of one another which makes control of the process difficult. Additionally, process materials must withstand the corrosion effects of the chloride. The system must be kept meticulously anhydrous and air-free to avoid plugging resulting from the formation of niobium oxide trichloride, NbOQ. Distillation has been used commercially in the past. 

On the other hand, wet chlorination of refinery slimes has proven to be a rapid and simple method of obtaining high extractions of selenium from slimes. A simple wet chlorination flow sheet is shown in Figure 3. Slimes chlorination per se is not a simple deselenization operation, but rather a process wherein virtually all the constituents of slimes which form soluble chlorides report as a complex solution of mixed chlorides. Thus the use of wet chlorination requires a complete change in the process to recover the metal values in slimes. The first plant to use wet chlorination of slimes was started by Kennecott (Salt Lake City, Utah) in 1995. 

Hydrochloric acid digestion takes place at elevated temperatures and produces a solution of the mixed chlorides of cesium, aluminum, and other alkah metals separated from the sUiceous residue by filtration. The impure cesium chloride can be purified as cesium chloride double salts such as cesium antimony chloride [14590-08-0] 4CsCl SbCl, cesium iodine chloride [15605 2-2], CS2CI2I, or cesium hexachlorocerate [19153 4-7] Cs2[CeClg] (26). Such salts are recrystaUized and the purified double salts decomposed to cesium chloride by hydrolysis, or precipitated with hydrogen sulfide. Alternatively, solvent extraction of cesium chloride direct from the hydrochloric acid leach Hquor can be used. 

Mukherjee studied the gas phase equilibria and the kinetics of the possible chemical reactions in the pack-chromising of iron by the iodide process. One conclusion was that iodine-etching of the iron preceded chromis-ing also, not unexpectedly, the initial rate of chromising was controlled by transport of chromium iodide. Neiri and Vandenbulcke calculated, for the Al-Ni-Cr-Fe system, the partial pressures of chlorides and mixed chlorides in equilibrium with various alloys and phases, and so developed for pack aluminising a model of gaseous transport, solid-state transport, and equilibria at interfaces. 

In addition to the thermal CVD reactions described above, a glow discharge plasma at 480-650°C has been used to deposit HB2 from the mixed chlorides,... 

Mixed-Chloride-lodide Zirconium Cluster Phases with a 6 12-Metal Halide Ratio 63 5.3... 

Mixed Chloride-Iodide Zirconium Cluster Phases with a 6 18 Metal Halide Ratio -Products from Solid-state Reactions... 

Cerium(IV) oxidises tin(II) in aqueous sulphuric acid probably by a two-step path involving Sn(III). At low Sn(IV) concentrations and low sulphate concentration the reaction is second order, and the suggestion is made that the reactant species are Ce(S04)3 and SnS04. In mixed chloride-sulphate media the Ce(IV)- -Sn(II) reaction, in the presence of trioxalatocobaltate(III), produces an intermediate which consumes the Co(III) complex . This result is interpreted as being evidence for the presence of Sn(III) in the reacting system. 

The volatilities of both zirconium tetrachloride and hafnium tetrachloride are very similar to each other at normal operating temperatures, and their separation by a simple distillation or fractional distillation operation is not viable. However, when the mixed chloride vapor is contacted with an eutectic molten salt mixture of aluminum chloride and potassium chloride, zirconium chloride is preferentially absorbed. The vapor pressure difference between zirconium and hafnium tetrachlorides is greatly enhanced over the molten... 

Explosions sometimes resulted on opening sealed tubes in which complex mixed chloride salts of this compound had been prepared. There is no obvious source of pressure in the reaction mixture of tungsten hexachloride, sodium and aluminium chlorides and aluminium metal. 

Shell Deacon An improved version of the Deacon process for oxidizing hydrogen chloride to chlorine, using a catalyst containing the mixed chlorides of copper, potassium, and rare earths. Formerly operated in The Netherlands and still in operation in India. 

Mixed chlorides can also be used to produce intermetallics ... 

Gallium(III) chloride also combines with other metal chlorides such as CaCls or CrCls to form mixed chlorides that have halogen bridge structures i.e., Cl4Ta(-Cl)2. Many such compounds are volatile. 

Precious metals Mixed chloride solution (Au, Pt, Pd) 8-Hydroxyquinoline derivatives in aromatic solvent... 

---