Solid-Liquid Phase Equilibria For The Conversion Process Of Aluminum Hypophosphite Production

Sodium hypophosphite as raw materials, the use of the preparation of aluminum hypophosphite conversion reaction is an effective method to obtain aluminum hypophosphite flame retardant with high purity and specific size requirements.Improve the conversion rate and product purity is the main target of the method of process optimization.Conversion reactionIn of 6NaH2PO2+Al2(SO4)3= 2Al(H2PO2)3+3Na2SO4, In the process of reaction involving four binary system,four ternary system and an interactive quaternary system,to master the solid liquid equilibrium of these systems is the basis of process design, optimization and control. However, the lack of related to the phase diagram data.So this paper carried out Solid-Liquid Phase Equilibria for the Conversion Process of Aluminum Hypophosphite Production,which will enrich the basic data of salt-water system and guide Al(H2PO2)3 production.There is a very important significance.The classical methodology of’isothermal solubility equilibrium’was adopted to determine the SLE data of Al(H2PO2)3-Al2(SO4)3-H2O, Al(H2PO2)3-NaH2PO2-H2O, NaH2PO2-Na2SO4-H2O,Al2(SO4)3-Na2SO4-H2O and Na+,Al3+//SO42-,H2PO2-H2O at 50℃, and used the methods of XRD and wet slag to analyzed the composition of solid phase, and draw the phase diagram of the ternary system at 323.15K. The results proved that:(1) The method using alkali-soluble aluminum hypophosphite is easy to operate, and the measurement results are more stable and reliable.This method has been the industrial aluminum hypophosphite chemical industry standard adopted, program number is: 2013-1129T-HG. The solubility of aluminum hypophosphite decreases with the increase of temperature.(2) Al(H2PO2)3-A12(SO4)3-H2O ternary system belong to the phase diagram with doubles salt generated. There were four regions in the phase diagram,namely Al2(SO4)3-16H2O crystalline region,the crystallization of Al(H2PO2)3 area, Al(H2PO2)3-A12(SO4)3·16H2O crystalline region and unsaturated zone.(3) Al(H2PO2)3-NaH2PO2-H2O ternary system belongs to the simple system phase diagram. There were three regions in the phase diagram, namely the NaH2PO2-H2O crystalline region,crystalline region of Al(H2PO2)3 and unsaturated zone.(4) Al2(SO4)3-Na2SO4-H2O ternary system belong to the phase diagram with doubles salt generated. There were four regions in the phase diagram,namely A12(SO4)3-16H2O crystalline region,the crystallization of Na2SO4 area,NaAl(SO4)2·6H2O crystalline region and unsaturated zone.(5) NaH.2PO2-Na2SO4-H2O ternary system belongs to the simple system phase diagram. There were three regions in the phase diagram, namely the NaH2PO2·H2O crystalline region crystalline region of Na2SO4 and unsaturated zone.(6) Conversion reaction completion time with the temperature rise rapidly decreases, and above 70℃, reaction completion time is less than 1 hour.The reaction conversion rate increases with temperature rise, above 70℃, the reaction conversion rate of 95% or more.The interaction quaternary system Na+,Al3+//SO42-,H2PO2--H2O phase diagram obtained the Co-saturated lines of Na2SO4 and Al(H2PO2)3, Al(H2PO2)3 and NaAl(SO4)2, 3 and Al(H2PO2)3-Al(H2PO2)3·Al2(SO4)3 and A12(SO4)3.