Abstract: The plant is provided with a first rotary reactor where the balls of urea cyanurate are formed and a second reactor where the pyrolysis takes place. The first reactor is provided with an internal helical fin and the second reactor is also rotary. At the exit thereof there is a communication tube placing it in communication with a solids separator vessel which receives an aqueous solution capable of reaching a working level, below which there is the access port of the tube to the vessel. The vessel is provided with a lower drain valve and an upper gas exhaust tube.

Abstract: The method uses a starting material which is a liquid mixture including a formaldehyde proportion between 48 to 55% by weight, a methanol proportion between 20 and 30% by weight and a water proportion between 32 and 15 wt %; the liquid mixture is obtained from a tapping which is effected from a plant for the continuous preparation of urea-formaldehyde resins and glues, immediately after having subjected the methanol to catalytic oxidation via air, condensation of the gases evolving from said catalytic oxidation and separation between condensed products and uncondensed gases. These solutions may be applied to formaldehyde reactions wherein it is of interest to reduce the amount of water present in conventional solutions and also to use the methanol for example as solvent for the final product obtained.