Patent GB-411587-A (GB)
Title: Improvements in the separation of mixtures of alkali metal nitrates with ammonium chloride
IPC: C01D9/10
Filed: 1933-01-28
Abstract: Salt mixtures composed of alkali metal nitrate and ammonium chloride are separated by subjecting the mixture to flotation in an aqueous medium containing a flotation agent.  The ammonium chloride passes into the froth and the alkali metal nitrate remains at the bottom of the flotation vessel.  The salt mixtures are preferably suspended in the mother liquids resulting from the double decomposition of alkali metal chloride with ammonium nitrate.  The flotation medium may be acid or alkaline, e.g. with ammonia.  The flotation agent may be the oils used in the flotation of ores and organic compounds which are either only collecting agents or only frothing agents or which possess both these properties, either alone or in admixture.  The production of froth may be effected by mechanical stirring, by the introduction of a diffused current of air or other gas under pressure, by the aid of currents of liquid, by means of vacuum or by spraying the liquid under treatment.  The destruction of the froth for recovering the ammonium chloride may be effected by spraying water or alkaline liquids thereon or by stirring slowly and heating. The process may be carried out in counter-current in several vessels, the alkali metal nitrate which has not been freed completely from ammonium chloride in the first vessel being conveyed to a second flotation vessel and the froth resulting from the second vessel after having removed the last portions of ammonium chloride being conveyed to the first vessel and then being caused to separate from the ammonium chloride in one or two treatments.  According to examples, (1) equimolecular proportions of sodium nitrate and ammonium chloride, obtained by the double decomposition of sodium chloride with ammonium nitrate is subjected to flotation in the liquor from the decomposition by adding oleic acid and cresol and stirring with air, the froth together with a part of the liquor being conveyed to a second chamber and slowly stirred while heating to 45 DEG  C. to separate ammonium chloride; (2) a conversion liquid, employed in circulation, has added to it potassium chloride and ammonium nitrate and is stirred for several hours at 20 DEG  C., or higher the mixture then being subjected to flotation as in example (1) to produce ammonium chloride and potassium nitrate and the mother liquor separated from the salts by centrifuging being employed for the conversion of further batches of the initial salts; (3) in carrying out the process of example (1), a viscus mineral oil such as a lubricating oil is employed as the flotation agent, the froth being stirred slowly at 60 DEG  C. in a second vessel in order to separate the ammonium chloride; (4) ammonium nitrate and sodium chloride are introduced into a liquor while stirring at 40 DEG  C., the product being subjected to flotation at ordinary temperature employing hempseed oil as the agent to produce ammonium chloride and sodium nitrate.ALSO:Salt mixtures composed of alkali metal nitrate and ammonium chloride are separated by subjecting the mixture to flotation in an aqueous medium containing a flotation agent.  The ammonium chloride passes into the froth and the alkali metal nitrate remains at the bottom of the flotation vessel.  The salt mixtures are preferably suspended in the mother liquids resulting from the double decomposition of alkali metal chloride with ammonium nitrate.  The flotation medium may be acid or alkaline, e.g. with ammonia.  The flotation agents may be the oils used in the flotation of ores and organic compounds which are either only collecting agents or only frothing agents or which posses both these properties, either alone or in admixture.  The production of froth may be effected by mechanical stirring, by the introduction of a diffused current of air or other gas under pressure, by the aid of currents of liquid, by means of vacuum or by spraying the liquid under treatment.  The destruction of the froth for recovering the ammonium chloride may be effected by spraying water or alkaline liquids thereon or by stirring slowly and heating. The process may be carried out in counter-current in several vessels, the alkali metal nitrate which has not been freed completely from ammonium chloride in the first vessel being conveyed to a second flotation vessel and the froth resulting from the second vessel after having removed the last portions of ammonium chloride being conveyed to the first vessel and then being caused to separate from the ammonium chloride in one or two treatments.  According to examples, (1) equimolecular proportions of sodium nitrate and ammonium chloride, obtained by the double decomposition of sodium chloride with ammonium nitrate is subjected to flotation in the liquor from the decomposition by adding oleic acid and cresol and stirring with air, the froth together with a part of the liquor being conveyed to a second chamber and slowly stirred while heating to 45 DEG  C. to separate ammonium chloride; (2) a conversion liquid, employed in circulation, has added to it potassium chloride and ammonium nitrate and is stirred for several hours at 20 DEG  C. or higher, the mixture then being subjected to flotation as in example (1) to produce ammonium chloride and potassium nitrate and the mother liquor separated from the salts by centrifuging being employed for the conversion of further batches of the initial salts; (3) in carrying out the process of example (1), a viscous mineral oil such as a lubricating oil is employed as the flotation agent, the froth being stirred slowly at 60 DEG  C. in a second vessel in order to separate the ammonium chloride; (4) ammonium nitrate and sodium chloride are introduced into a liquor while stirring at 40 DEG  C., the product being subjected to flotation at ordinary temperature employing hempseed oil as the agent to produce ammonium chloride and sodium nitrate.