GB737468A - Preparation of urea-formaldehyde condensate fertiliser compositions - Google Patents

Abstract

Urea-formaldehyde condensates for use as fertilizers are prepared by mildly agitating at 20-65 DEG C. and pH 1-6 a mixture of 1 mol. formaldehyde, 1.5-4.5 mols. of urea and 20-80 mols. of water. The pH of the mixture is adjusted to at least 6 and the precipitated urea-formaldehyde condensate separated or the precipitated product is separated and its pH adjusted to at least 6. Formamide, acetamide or propionamide may be added as chain-stoppers. The amount of agitation is sufficient to prevent settling of precipitated solids and is such that the initial precipitate having a particle size of 2-6 microns agglomerates to an average particle size of 20-200 microns. Neutralization is preferably effected with a base, e.g. CaCO3 which will remove from the solution the anion of the acid, e.g. H2SO4 used to obtain the desired acidity for the condensation. The product, if desired after screening, is granulated by tumbling in 75-200 per cent of water and then dried. Starch or urea may be added as granulating agents. Reaction may be batchwise, continuous or semi-continuous. If desired separate streams of reactants may be led into a tubular reactor. Preferably the filtrate from the precipitated product is recycled with appropriate quantities of fresh reactants. The formaldehyde may be used as an aqueous solution or as paraformaldehyde, trioxane, hexamethylenetetramine, dimethylol urea or as methylol urea as disclosed in Specification 641,703. Formic acid in aqueous formaldehyde solutions may be sufficient to give the desired pH. The urea may be added as solid or in solution. The reaction may be performed in a vessel of wood, stainless steel, glass, enamel or stoneware. The vessel may be jacketed or an external heat exchanger may be provided. The products may be employed as such or admixed with fertilizer ingredients, e.g. nitrates, potassium salts or phosphates. Products formed with a relatively high mol. ratio of urea may be employed as feed supplements for cattle. The products have an insoluble nitrogen content of at least 60 per cent and an availability index of at least 45 per cent both according to tests defined in the Specification.ALSO:Urea-formaldehyde condensates for use as fertilizers are prepared by mildly agitating at 20-65 DEG C. and pH 1-6 a mixture of 1 mol. formaldehyde, 1.5-4.5 mols. of urea and 20-80 mols. of water. The pH of the mixture is adjusted to at least 6 and the precipitated urea-formaldehyde condensate separated or the precipitated product is separated and its pH adjusted to at least 6. Formamide, acetamide or propionamide may be added as chain-stoppers. The amount of agitation is sufficient to prevent settling of precipitated solids and is such that the initial precipitate having a particle size of 2-6 microns agglomerates to an average particle size of 20-200 microns. Neutralization is preferably effected with a base, e.g. CaCO3 which will remove from the solution the anion of the acid, e.g. H2SO4 used to obtain the desired acidity for the condensation. The product, if desired, after screening is granulated by tumbling in 75-200 per cent of water and then dried. Starch or urea may be added as granulating agents. Reaction may be batchwise, continuous, or semi-continuous. If desired separate streams of reactants may be led into a tubular reactor. Preferably the filtrate from the precipitated product is recycled with appropriate quantities of fresh reactants. The formaldehyde may be used as an aqueous solution or as paraformaldehyde, trioxane, hexamethylenetetramine, dimethylol urea or as methylol urea as disclosed in Specification 641,703. Formic acid in aqueous formaldehyde solution may be sufficient to give the desired pH. The urea may be added as solid or in solution. The reaction may be performed in a vessel of wood, stainless steel, glass, enamel or stoneware. The vessel may be jacketed or an external heat exchanger may be provided. The products may be employed as such or admixed with fertilizer ingredients, e.g. nitrates, potassium salts or phosphates. Products formed with a relatively high mol. ratio of urea may be employed as feed supplements for cattle. The products have an insoluble nitrogen content of at least 60 per cent and an availability index of at least 45 per cent both according to tests defined in the Specification.ALSO:A urea-formaldehyde condensate with an insoluble nitrogen content of at least 60 per cent and an availability index as defined in the Specification of at least 45 per cent (see Group IV (a)) is employed as a feed supplement for cattle or other ruminants. The products, which are preferably granulated by tumbling in water, may also be employed as fertilizers, if desired in admixture with any other known fertilizer compositions or ingredients, e.g. nitrates, potassium salts or phosphates.