Patent GB-373217-A (GB)
Title: Improvements in processes and apparatus for the production of chemical compounds or metals from raw materials
IPC: B01J19/20
Filed: 1931-02-16
Abstract: In a process of treating raw materials containing amphoteric metals such as aluminium, beryllium, tin, zinc, chromium, manganese, molybdenum, vanadium or tungsten and non-amphoteric metals such as iron, copper, nickel or cobalt for the production of the metals or of compounds thereof, the raw material is dissolved in hydrochloric acid, an alkali or alkaline earth chloride is added, and the solution is introduced into a reaction chamber wherein it is submitted to the action of sulphur oxides with simultaneous evaporation and calcination at an increasing temperature; the sulphates formed are decomposed, the resultant sulphur oxides remaining in the chamber reacting with freshly added material.  The alkali or alkalineearth salts of the amphoteric metal oxides and the oxides of the other metals are removed.  The former, if soluble, may be recovered from the mass by lixiviation with water, but if <PICT:0373217/III/1> insoluble, for example, in the case of calcium aluminate, the mass is leached with alkali carbonate.  In an example, clay roasted at 800 DEG  C. is dissolved in hydrochloric acid and filtered; sodium chloride is added, and preferably also, carbonaceous material such as sugar, glucose, dextrin, wood sugar, or molasses.  The reaction mixture as a foam is fed into a retort which may be vertical or inclined, but preferably as shown in the Figure, via pipe 56.  At the commencement of the process sodium sulphate is also added. Alternatively, sulphur oxides are introduced into the retort via pipe 58.  It is heated by burners 60, a temperature of 1000-1100 DEG  C. being maintained at this end.  The mixture is moved down the shaft by screw-conveyer 52.  Hydrochloric acid evolved escapes by pipe 57.  To ensure no loss of sulphur oxides, which circulate in the retort, partly in sulphate form, steam, or nitric acid, for example, in the form of saltpetre, and oxygen, air or steam may be introduced by pipe 58 to facilitate conversion of sulphur dioxide to sulphur trioxide. The converted mixture is conveyed by screws 64, 66 to vessel 67 wherein it is leached with water.  Pure alumina and caustic soda or soda, or cryolite may be obtained by stirring or by adding carbon dioxide or hydrofluoric acid to the solution filtered from the insoluble metal oxides.  In a modified form of charging apparatus, the reaction mixture passes down the hollow shaft of a reciprocating plunger disposed at the top of the retort and preferably of concave lower surface. Aluminous materials specified other than clay are bauxite, leucite, labradorite.  Potassium, calcium or magnesium if present are converted to aluminates.  The Specification as open to inspection under Sect. 91 (3) (a) comprises also the production in a similar manner of lithium compounds from petalite, lepidolite and mica, also the addition of manganese dioxide as an oxidizing agent to the reaction material, and also leaching of the mass containing sodium aluminate with an acid such as hydrochloric acid.  This subject-matter does not appear in the Specification as accepted.