GB712178A - Improvements in and relating to the production of nitrogenous fertilizers - Google Patents

Abstract

A urea-aldehyde condensate, for use as a fertilizer, is made by reacting urea and formaldehyde in aqueous solution of not more than 90 per cent. total concentration by weight and in the molar ratio of urea to formaldehyde of 1:1 to 2:1, in the absence of added condensation or buffer agents, at a temperature of 70 DEG to 110 DEG C. for a period of up to 40 minutes, whereby a thickened mixture is obtained which is solidified by further application of heat or by cooling and is then broken up to give particles of desired size which are dried at 130 DEG C. or below. The formaldehyde, e.g. as an aqueous solution or as paraformaldehyde, may be added to an aqueous solution of urea which may have an initial temperature of 110 DEG C., or solid urea may be added to an aqueous solution of formaldehyde. The formaldehyde solution may be pre-heated to 70 DEG C. before addition to the urea solution or before solid urea is added thereto. The thickened mixture may either be cooled and solidified in the reaction vessel or solidified by discharge therefrom on to a chilled or heated metal roll or plate; in the latter method hardening is accelerated by adding a little mineral acid, e.g. nitric acid, to the mixture before discharge from the reaction vessel. The dried product may be crushed to a powder, and the dried or crushed product may be granulated with the addition of moisture e.g. in amount of 20 per cent. by weight, and if desired with (a) an inert diluent such as anhydrite, gypsum or starch, e.g. in amounts equal to the weight of the powdered product, or (b) other fertilizers, such as ground ammonium sulphate, e.g. in amounts of 10 per cent. by weight of the powdered product. Examples are given.ALSO:A nitrogenous fertilizer comprises a dried or crushed urea-aldehyde condensate (see Group IV(a)) which may be granulated by the addition of moisture, e.g. in amount of 20 per cent by weight, and, if desired, with (a) an inert diluent such as anhydrite, gypsum or starch, e.g. in amount equal to the weight of the powdered condensate, or (b) other fertilizers such as ground ammonium sulphate, e.g. in amount of 10 per cent by weight of the powdered condensate.