Process for Preparing Ammonic Glyphosate Granules

Abstract

A process for preparing water-soluble granules of amnionic glyphosate comprising: a) addition of glyphosate acid to a Broensted base which supplies ammonium ions in a molar ratio base/acid comprised between 0.8 and 1.1; b) homogenization of the mixture prepared in a); c) addition of one or more surfactants in amounts in the range 5%-50% by weight based on the glyphosate acid; d) mixing of the mass prepared in c) for a time lower than about 10 minutes until obtaining an extrudable mass; e) extrusion of the mass obtained in d); f) drying until obtaining a granule having a residual moisture lower than 1%.

1 . A process for preparing water-soluble ammonic glyphosate granules comprising:
 a) addition of glyphosate acid, under wet cake form, to a solid Broensted base, which supplies ammonium ions, in amounts equal to a molar ratio base/acid between 0.8 and 1.1, preferably between 0.9 and 1.05, optionally in the presence of coformulating agents such as inert, antifoam agents;   b) homogenization of the mixture prepared in a);   c) addition of one or more liquid surfactants, in amounts in the range 5%-50% by weight, preferably 10%-40%, more preferably 12%-35% based on the glyphosate acid;   d) mixing of the mass prepared in c) for a time lower than about 10 minutes, preferably lower than about 5 minutes, more preferably comprised between about 30 seconds and 3 minutes, until obtaining an extrudable mass;   e) extrusion of the mass obtained in d);   f) drying until obtaining a granule having a residual moisture lower than 116, preferably lower than 0.5%.   
     
     
         2 . A process according to  claim 1 , wherein the Broensted base of step a) is selected from ammonium carbonate, bicarbonate, carbamate or mixtures thereof, optionally added of small amounts of antipacking agents as, for example, magnesium carbonate. 
     
     
         3 . A process according to  claim 2 , wherein the base is an equimolar mixture of ammonium carbonate, bicarbonate, carbamate. 
     
     
         4 . A process according to  claims 1 , wherein the inert agents of step a) are selected from ammonium sulphate, potassium sulphate, sodium sulphate, preferably ammonium sulphate. 
     
     
         5 . A process according to  claims 1 , wherein the antifoam agent is a silicone antifoam agent. 
     
     
         6 . A process according to  claims 1 , wherein the step b) takes place under mild stirring, preferably in a mixer working at a revolution number between 20 and 40 rpm. 
     
     
         7 . A process according to  claims 1 , wherein the surfactant addition of step c) takes place under mild stirring, preferably in a mixer working at a revolution number between 20 and 40 rpm. 
     
     
         8 . A process according to  claims 1 , wherein the surfactant is selected from solid or liquid surfactants at room temperature, preferably from alkanol amide, betaine derivative, ethoxylated-propoxylated block copolymer, glycerol ester, glycolic ester, imidazoline and its derivatives, lanolin and lecithin derivatives, tertiary and quaternary polyoxyalkylenalkyl amines, polyoxyalkylen alkylether, polyoxyalkylen alkyl aryl ether, polyoxyalkylen alkyl ester, alkoxylated and non alkoxylated sorbitan ester, alkyl glycoside, alkyl polyglycoside, alkyl sulphate, alkyl phosphate, sulphonated olefin, alkyl aryl sulphonate, polyoxyalkylen alkyl ether sulphate, polyoxyalkylen alkyl ether phosphate, sulphosuccinate derivative, taurate, vegetable oil sulphonate of a fat acid, of an alcohol, of an alcoholalkoxylate, of a fat acid ester, an aromatic derivative of a fat acid ester or mixtures thereof, amine derivatives of vegetable oils or of fat acids. 
     
     
         9 . A process according to  claims 1 , wherein the surfactant is ethoxylated tallow amine, having general formula
   R—N(CH 2 CH 2 O)H m (CH 2 CH 2 O)H n      
       with R=saturated alkyl chain having 16-18 carbon atoms. 
     
     
         10 . A process according to  claims 1 , wherein the step d) is carried out under stirring with a higher intensity than that of step c), preferably in a mixer, optionally equipped with chopper, working at a rate between about 80 and 120 rpm. 
     
     
         11 . A process according to  claim 10 , wherein the mixer choppers are used. 
     
     
         12 . A process according to  claims 1 , wherein the extrusion of step e) is carried out by low pressure extruders, preferably basket extruders. 
     
     
         13 . A process according to  claims 1 , wherein the drying of step f) is carried out in fluid bed dryers, preferably at temperatures in the range 70° C.-120° C., more preferably 80° C.-100° C. 
     
     
         14 . A process according to  claim 13 , wherein the time used for drying ranges from 10 to 15 minutes. 
     
     
         15 . Granules of monoammonic glyphosate obtainable by the process of  claims 1 . 
     
     
         16 . Granules according to  claim 15 , wherein the content of equivalent glyphosate acid is higher than or equal to 48% by weight. 
     
     
         17 . Granules according to  claims 15 , wherein the surfactant content is between 5% and 25% by weight. 
     
     
         18 . Granules according to  claims 15 , wherein the surfactant content is between 10% and 20% by weight.