Patent GB-887393-A (GB)
Title: Process of preventing the formation of emulsions
IPC: B01D11/02
Filed: 1959-09-01
Abstract: Emulsion formation is repressed in extraction systems wherein an organic solvent is contacted with an aqueous solution of an inorganic chemical, which solution also contains colloidal inorganic substances promoting emulsion formation, by adding to at least one of the aqueous and organic phases a free elemental carbonaceous material, such as vegetable charcoal, activated carbon, graphite, coke or bituminous or anthracite coal.  These materials are employed as powders of less than 100 mesh average particle size and are preferably added in the form of an aqueous suspension.  The invention is particularly applicable to aqueous solutions of uranyl, thorium and rare nitrates, ferric chloride, cerium oxide and sodium uranate, which also contain colloidal impurities such as silica, titanium, zircon, or monazite.  Organic solvents in such processes may be tributyl phosphate, ketones such as methyl isobutyl and diethyl ketone, methyl acetate or mesityl oxide.  Such solvents may be employed in the presence of aromatic or aliphatic hydrocarbon diluents.  According to Examples:- (1) a crude thorium oxide was treated with nitric acid and the resulting solution of nitrates was concentrated, sodium nitrate added thereto, and the free acidity brought to 0,4 molar.  The solution was treated with a mixture of tributyl phosphate and a petroleum aliphatic hydrocarbon solvent which contained active carbon, charcoal or graphite.  Emulsification was repressed by adding active carbon to the aqueous phase before mixing or by adding ground coke to the already mixed and emulsified phases, whereupon separation occurred.  (6) A ground uraniferous ore was treated with concentrated nitric acid and the system maintained at 95 DEG C. with stirring for one hour.  On dilution and cooling a semicolloidal suspension of high viscosity was formed; active carbon was added and the resulting mixture was extracted with tributyl phosphate in a petroleum hydrocarbon solvent; no emulsification occured.  (7) Crude sodium uranate was dissolved in nitric acid and the uranyl nitrate solution so formed was extracted with tributyl phosphate and an aliphatic petroleum hydrocarbon.  Emulsification occurred until a suspension of active carbon in water was added to the emulsion with agitation, whereupon separation of the two phases occurred.  (8) Crude ceric oxide was dissolved in nitric acid containing a minor amount of sodium chloride and after dilution the free acidity was brought to 1 molar.  Active carbon was added to a mixture of tributyl phosphate and petroleum hydrocarbon solvent which was then contacted with the cerium nitrated solution.  Emulsification was suppressed.  Alternatively, a suspension of vegetable carbon in water could be added to the emulsion after it had formed, in which case rapid agitation followed by slow agitation effects separation of the phases.  (9) A finely divided oxidic iron ore was treated with hydrochloric acid and the ferric chloride solution contained colloidal insoluble materials.  Free acidity was adjusted to 6 molar and the solution then treated with ethyl acetate containing active carbon.  The emulsion formed separated on cessation of agitation. Alternatively, an aqueous suspension of charcoal in water could be added to the emulsion after it had formed, thereby effecting de-emulsification.  (15) A crude sodium uranate solution was treated with diethylhexylamine and carbon was added to the emulsion as an aqueous suspension, whereupon the phases separated.  (16) An uraniumbearing zircon ore was finely ground, mixed with sodium carbonate and heated at 950 DEG C.  The mixture formed was suspended in water, reacted with nitric acid at 80 DEG C. and diluted.  The resultant mixture was agitated with dibutyl phosphate and benzene which contained carbon and the emulsion formed on agitation separated on standing.  Active carbon in aqueous suspension may also be added to the emulsion formed between the two phases.