湿法浓磷酸自动反洗表面过滤净化技术研究及应用

介绍湿法浓磷酸自动反洗表面过滤净化装置的工作原理及具体的操作工艺,确定浓磷酸自动反洗表面过滤净化的最佳工艺条件为:过滤压力小于0.02 MPa,反冲周期12 min,反冲时间10 s,清洗周期18 h,稀硫酸溶液清洗时间1.5 h,清洗液w(H_2SO_4)12%,清洗液温度80℃,氢氧化钠溶液清洗时间1.5 h,清洗液w(NaOH)15%,清洗液温度70℃,同时清洗过程辅以蒸汽加热及压缩空气曝气。该工艺条件下,浓磷酸w(固)由4.5%降至0.8%以下,减少浓磷酸储罐投用量近1/4,缩短浓磷酸陈化周期近30%,减少带入磷复肥生产系统中的杂质沉淀量约为30 000 t/a,有效提高浓磷酸品质,稳定磷复肥产品质量。

Study and application of automatic backwashing surface filtration & purification technology for concentrated

The working principle and operation process of automatic backwashing surface filtration &purification plant are introduced, the optimum process conditions for the filtration & purification of concentrated phosphoric acid are as follows: the filtration pressure is less than 0.02 MPa,the recoil cycle of 12 min, the recoil time of 10 s, the cleaning cycle is 18 h, the cleaning time of dilute sulfuric acid solution is 1.5 h,the cleaning solution w(H2SO4) of 12% and the temperature of the cleaning fluid of 80 ℃,the cleaning time of sodium hydroxide solution of 1.5 h,the cleaning solution w(NaOH) of 15% and the temperature of the cleaning fluid of 70 ℃, and the cleaning process shall be supplemented with steam and compressed air aeration. Under the conditions,the solid content of the concentrated phosphoric acid is decreased from 4.5% to below 0.8%,reducing the concentration of concentrated phosphoric acid storage tank nearly 1/4,shortened the aging period of concentrated phosphoric acid standing nearly 30%,reducing the amount of impurity precipitation brought into the phosphate fertilizer production system about 30 kt/a, effectively improving the quality of raw materials of concentrated phosphoric acid,and the quality of phosphate compound fertilizer is more stable.