拜耳法赤泥制备三聚磷酸铝

拜耳法赤泥经石灰石烧结改性、盐酸浸取及碱液处理等工序得到氢氧化铝干胶,再以氢氧化铝干胶和工业磷酸为原料,通过中和反应、缩合反应和水化反应合成三聚磷酸铝.经单因素条件实验和正交实验得到最佳工艺条件为:磷酸体积(mL)与氢氧化铝干胶质量(g)的比3,中和反应温度常温,缩合反应温度290℃,缩合反应时间4h.在最佳工艺条件下合成的试样中,Al2O3和P2O5的含量与工业三聚磷酸铝ATP-200相近,经IR分析,该试样即为三聚磷酸铝.盐雾试验结果表明合成的三聚磷酸铝的防腐性能达到ATP-200的性能指标.

Preparation of Aluminum Tripolyphosphate from Red Mud in Bayer Process

Red mud in Bayer process was treated by the processes of sintering with limestone,leaching with hydrochloric acid,reaction with alkaline liquor,and so on,to obtain dry aluminium hydroxide gel.Then the dry aluminium hydroxide gel and industrial grade phosphoric acid were used as raw materials to synthesize aluminum tripolyphosphate by neutralization,condensation and hydration reactions.The optimum process conditions obtained by single factor experiments and orthogonal experiments are as follows:ratio of phosphoric acid volume(mL)to dry aluminium hydroxide gel mass(g)3,room temperature for neutralization,condensation temperature 290 ℃,condensation time 4 h.Under these conditions,the contents of Al2O3 and P2O5 in the product are similar to those in industrial grade aluminum tripolyphosphate ATP-200.The IR analysis result also confirms that the product is aluminum tripolyphosphate.The results of salt spray test show that the anticorrosive property of the product can meet the standard of ATP-200.