Study On Solid Phase Preparation Of High Degree Of Polymerization Of Condensed Aluminum Phosphate And Its Application In Sodium Silicate Cement

High degree of polymerization of condensed aluminum phosphate is a kind of polyphosphoric acid aluminum salt which it’s degree of polymerization greater than3, and structurally different from the current market research and development of aluminum tripolyphosphate product. There have litter domestic study reports about synthesis process of high degree of polymerization of condensed aluminum phosphate and its performance, in order to development the products based on the rich bauxite resources in Guangxi. Therefore, it is necessary to carry out the research of synthesis and performance of high degree of polymerization of condensed aluminum phosphate. In this paper, high degree of polymerization of condensed aluminum phosphate was synthesized from ammonium dihydrogen phosphate and aluminum hydroxide as raw material, mainly study on synthesis process of high degree of polymerization of condensed aluminum phosphate by using solid state reaction and the application of it used in the sodium silicate cement as a curing agent. The main research conclusions are as follows:(1) Developed a new process of high degree of polymerization of condensed aluminum phosphate by using solid phase method, it is as follows: ammonium dihydrogen phosphate and aluminum hydroxide as raw material is able to get precursor by mixing, grinding, sieving, reaction and condensation, precursor after further condensation, hydration, drying, crushing, sieving to obtain a high degree of polymerization of condensed aluminum phosphate.(2) The single factor experiment and orthogonal experiment show that all factors on the influence of the content of precursor of aluminum tripolyphosphate was that:condensation temperature> n(NH4H2PO4)/n(Al(OH)3)> reaction temperature. And the optimum preparation process conditions were determined as follows:(NH4H2PO4)/n(Al(OH)3) is3.5, the reaction temperature is200℃, reaction time is5hours, condensation temperature is350℃, the preparation content of precursor of aluminum tripolyphosphate is83.67%.(3) In the best conditions of prepare high degree of polymerization of condensed aluminum phosphate, use aluminum tripolyphosphate content as indirect characterization index, discusses the further condensation temperature and further condensation time on the content of condensation aluminium phosphate in aluminum tripolyphosphate. The results show that the content of condensation aluminum tripolyphosphate was reduced along with the increase of temperature. The content of aluminum tripolyphosphate tend to be gentle after first decrease along with the increase of further condensation time. And the further condensation parameters were determined as follows:the further condensation temperature is below600℃, the further condensation time is3 hours.(4) Study the influence of high degree of polymerization of condensed aluminum phosphate to the sodium silicate cement. The result show that high content of high degree of polymerization of condensed aluminum phosphate as sodium silicate cement curing agent, the performance indicators can meet with the relevant requirements of the national standards, and the compressive strength of35.4MPa much larger than sodium fluosilicate as the compressive strength of the curing agent, so it can be used as a substitute for sodium fluosilicate.