GB866856A - Improvements in the production of ballast-free potassium ammonium nitrate - Google Patents

Abstract

A ballast-free potassium ammonium nitrate is prepared by alternately treating a cationexchanger with an aqueous solution of potassium chloride and then regenerating the exchanger with aqueous nitric acid in a series of columns, in which a portion of the regeneration solution is withdrawn, whilst still incompletely reacted, from the effluent of each of the columns, combining the withdrawn portions, neutralising the combined solution with ammonia, and evaporating to obtain a solid product. The total solution withdrawn in one cycle is such that it contains an amount of potassium nitrate equivalent to the capacity of one column, and such an amount of nitric acid that, after neutralisation with ammonia, the product has the desired N:K2O ratio, preferably 1:1.4 to 1:1.5. The solution remaining after a portion has been withdrawn is replenished with nitric acid before being passed to the next column. In an example the cation exchanger employed is a nuclearly sulphonated styrene divinylbenzene copolymer. The statement of prior art refers to a manner of preparing potassium nitrate by treating an aqueous potassium chloride solution with a cation exchanger and regenerating the exchanger with aqueous nitric acid in a plurality of series-connected columns through which the potassium chloride or nitric acid are passed. At the end of each column the top fraction (i.e. that part of the issuing solution which contains practically no potassium ions in the case of the passage of potassium chloride through the exchanger when charged with hydrogen, or that which contains practically no hydrogen ions in the case of the passage of nitric acid through the exchanger when charged with potassium) is withdrawn from the cycle for further processing, while the remaining fraction of the solution is fed to the next column, together with an amount of fresh potassium chloride or nitric acid equivalent to the top fraction withdrawn.ALSO:A fertilizer consisting of a potassium ammonium nitrate and a phosphate may be prepared by alternately treating a cation exchanger with an aqueous potassium chloride solution and then regenerating the exchanger with aqueous nitric acid in a series of columns, in which a portion of the regeneration solution is withdrawn, whilst still incompletely reacted, from the effluent from each of the columns, combining the withdrawn portions, adding thereto phosphates, which are preferably water- or citrate-soluble, neutralising with ammonia, and evaporating to obtain a solid product.