A method for the separation of nitric acid from a mixture of nitric acid with one or more of phosphoric, sulphuric or hydrochloric acids, in which the nitric acid is selectively extracted from a first phase comprising the acid mixture into a second phase by an amine nitrate. The method may conveniently be carried into effect by treating an aqueous mixture of acids with kerosene containing tri-n-octylamine nitrate and a modifyier e.g. decanol following which the excess nitric acid is stripped from the kerosene phase by water or dilute nitric acid.
The disclosure describes the recovery of sulfuric acid from industrial liquors containing the same. A selective liquid-liquid extraction of said liquors is carried out under conditions producing an organic phase containing the sulfuric acid and an aqueous phase eventually containing impurities. The organic phase is treated with a base, such as gaseous NH.sub.3, in order to separate the sulfuric acid. This process is simple, non-polluting, and requires little energy.
The present invention provides a process for manufacture of potassium nitrate from potassium chloride and nitric acid. A source of potassium chloride may be screened and separated into fine and coarse fractions, or the screening may be eliminated and the source may be separated into equal coarse fractions. The coarse fraction, when screening has occurred, or one of the equal fractions, where no screening has occurred, is dissolved in a dilute solution of nitric acid prior to any reaction. Thereafter, either the fine fraction (if screening occurred) or the other equal fraction (if no screening occurred) reacts with the dilute nitric acid-potassium chloride solution and additional nitric acid having a concentration of about 60% at ambient temperature. The resulting solution may be crystallized with or without the prior separation of solid potassium nitrate. Nitric acid is recovered by solvents from a residual brine solution after crystallization. The recovered nitric acid is washed to provide a nitric acid solution having a concentration of 3% to 10% which is recycled for use at the beginning of the process to dissolve the coarse fraction of potassium chloride prior to the reaction stage.
A method of recovering concentrated sulfuric acid from the product obtained from the acid hydrolysis of a cellulose-containing material such a biomass. The method involves contacting the product with an extraction solvent comprising one or more of the C.sub.4 -C.sub.7 alcohols as the major component to separate the product into a sulfuric acid enriched phase. The sulfuric acid from this enriched phase is then separated and recovered by a further extraction procedure.
