Abstract: The method for preparing hydrazodicarbonamide (HDCA) using biuret as a starting material is disclosed. The method comprises the steps of; obtaining metal monohalobiuret salt by reacting a biuret with a metal hypohalogen compound, or by reacting the biuret with a halogenating agent and a base; and reacting the obtained metal monohalobiuret salt with ammonia, wherein the hydrazodicarbonamide is produced in the presence of a catalyst including bromine or iodine atom and generating bromine or iodine ion during the reaction.

Abstract: The present invention relates to a method and apparatus for preparing hydrazodicarbonamide using urea as starting material economically and environmentally desirably. The apparatus includes a pyrolysis furnace to obtain biuret and ammonia by pyrolyzing urea; a recrystallization reactor to purify the biuret obtained from the pyrolysis furnace; a first reactor to obtain an metal monohalobiuret salt by reacting the biuret with metal hypohalogen compound or with halogen and base; a second reactor to synthesize the hydrazodicarbonamide by reacting the monohalobiuret metal salt with ammonia; and an ammonia evaporator to separate the excess ammonia from hydrazodicarbonamide and to supply the separated ammonia to an ammonia concentrator.

Abstract: A method for synthesizing hydrazodicarbonamide (HDCA) by a reaction of monohalobiuret metal salt having the formula 1 or 2, which is derived from biuret, and ammonia, wherein M is a metal and X is a halogen. The monohalobiuret metal salt is inexpensive and easy to synthesize and thus a great yield of HDCA can be obtained from the monohalobiuret metal salt at low cost.