GB782371A - Improvements in fused salt baths for use in the electrodeposition of refractory metals - Google Patents

Abstract

782,371. Electrolytic production of refractory metals; fused halide salt electrolytes. HORIZONS TITANIUM CORPORATION. Dec. 10, 1954 [Dec. 14, 1953], No. 35818/54. Class 41. A fused salt bath for use in obtaining electrolytically one of the refractory metals titanium, zirconium, hafnium, niobium, vanadium, and tantalum is produced by fusing at least one halide salt of an alkali or alkaline earth metal in admixture with a carbide of the refractory metal, a carbide-monoxide mutual solid solution of the refractory metal, or the refractory metal in impure form, and introducing into the resultant mass chlorine, phosgene, or a mixture of carbon monoxide and chlorine until the refractory metal content has been converted to lower valency chlorides in solution in the fused salt. The process may be carried out batchwise in an apparatus comprising three vertically superimposed graphite crucibles disposed in a graphite container heated by the passage of current therethrough and surrounded by a metal shell. Argon is passed continuously through the container and after the removal of air a fused melt of sodium chloride, potassium fluotitanate, and titanium carbide or carbidemonoxide or impure metal is formed in the top crucible. Chlorine is then fed into the melt and thereafter the titanium chloride-containing melt is run off through a graphite needle valve in the bottom of the crucible into the middle crucible which incorporates a petroleum coke filter in its bottom. The filtered melt is received in the third crucible where it is electrolysed using a carbon anode to yield a cathodic deposit of titanium and anodic evolution of oxides of carbon (formed from oxygen impurities in the bath) and chlorine. A similar process for niobium is described. Alternatively the evolved chlorine may be used to chlorinate the refractory metal starting material and together with the spent salt bath may be used to give a cyclic process. Specifications 778,218 and 788,295 are referred to.