Novel Study On Preparation Of Ammonium Polyphosphate By Industrial Mother Liquor Of Ammonium Phosphate

Ammonium polyphosphate,one of highly effective additive-type and intumescent flame retardant,is the nitrogen-phosphorus compound,creating a synergistic effect for flame retardant.Presently,the domestic industrial synthesis of ammonium polyphosphate with crystalline form??APP-??is mainly applied to the technical route with using the P₂O₅ as condensing agent and ammonium phosphate as raw material,while industrial mother liquor of ammonium phosphate as raw material and non-P₂O₅ as condensing agent to synthesize APP-?can further extend the way of synthesizing APP-?and make full use of the resources with industrial mother liquor of ammonium phosphate to enhance the high-value product and economic efficiency of enterprise and promote the optimization and upgrade of industrial structure and sustainable development of phosphorous chemical industry.The main research content of this article includes three parts.Firstly,preparation of monoammonium phosphate by industrial ammonium phosphate of mother liquor is studied.then,screening condensing agent to synthesized APP-?includes two processes:study on preparation of APP-?by melamine as condensing agent and by thiourea as condensing agent.Finally,several methods to synthesize APP-?are mutually compared by the several non-P₂O₅ as condensing agent,such as melamine and thiourea.Main conclusions are as follows.Industrial ammonium dihydrogen phosphate was obtained by industrial mother liquor of ammonium phosphate as raw materials after a series of steps to regulate pH value,filtrate,concentrate and crystallize were operated.The research result showed that the optimal process conditions were as follows.The reaction temperature was 80^°C,pH value was 4.1,relative density of concentration was 1.38,crystallization temperature was 20^°C and its corresponding time was 60 min.The obtained product under optimal conditions was characterized by XRD.It can be measured and all indexes were meetthe chemical industrial standard“Ammonium dihydrogen phosphate for industrial use HG/T 4133-2010”with?class.APP-?was obtained by monoammonium phosphate?MAP?as raw material and melamine?MEL?as condensing agent in the process of melting,foaming,solidification by passing ammonia and curing.The process to synthesize ammonium polyphosphate with crystalline form?showed that monoammonium phosphate and melamine had material mole ratio of 12:1,reaction temperature was 300^°C with flow rate 2 L/min of 6%wet ammonia,curing reaction time was 60 min after curing.The obtained product under optimal conditions was characterized by XRD and FT-IR,P₂O₅ and N content?wt%?and solubility of the product can meet the chemical industrial standard“Ammonium polyphosphate for industrial use HG/T 2770-2008”with?class.APP-?was obtained by ammonium dihydrogen phosphate?MAP?as raw material and thiourea?TU?as condensing agent in the process of melt,foaming,solidification and curing,respectively from the reaction temperature,reaction material ratio,ammonia atmosphere,curing reaction time of crystal conformation in a bid to explore its crystal effect in the preparation of ammonium polyphosphate.The process to synthesize APP-?showed that monoammonium phosphate and melamine had material mole ratio of 1:0.9,reaction temperature was 300^°C with flow rate 2 L/min of 6%wet ammonia,curing reaction time of crystal conformation was 60 min.The product was characterized by XRD and by FT-IR,P₂O₅ and N content?wt%?and solubility of obtained product under optimal conditions can meet the chemical industrial standard“Ammonium polyphosphate for industrial use HG/T 2770-2008”with?class.Several non-P₂O₅ as condensing agent,such as thiourea and melamine to synthesize APP–?have the extraordinarily similar process:melting,foaming,solidification and curing.The results are found by comparison that preparation of APP–?via different non-P₂O₅ condensing agents are different from the performance,hence on the basis of special material study various APP–?are valuble,useful and available so that the APP–?is more widely used in the field of flame retardant.