磷石膏制备高纯硫酸钙的循环工艺

摘要

In order to efficiently utilize the abundant CaSO4 resource in phosphogypsum,the high purity calcium sulfate product was prepared by chemical reagent recycling technology with phosphogypsum as a raw material.Firstly,phosphogypsum was decomposed by NaOH solution,and the SO2-4 was separated to get Na2SO4 solution.Then Ca2+ was dissolved from remaining calcium slag by hydrochloric acid solution,and the acid-insoluble residue was removed to get CaCl2 solution.High purity calcium sulfate precipitation and hydrochloric acid solution were obtained by adding sulfuric acid solution into the CaCl2 solution.Hydrochloric acid solution could be recycled and used to dissolve Ca2+ from calcium slag.Sulfuric acid and sodium hydroxide solutions could be obtained by electrolysis of Na2SO4 solution.The final purity of calcium sulfate was 99.72%,and the recovery rate of CaSO4 was 85.99%.%为高效利用磷石膏中丰富的CaSO4资源,采用化学试剂循环利用工艺,以磷石膏为原料,制备了高纯度硫酸钙产品.首先用NaOH溶液分解磷石膏,将其中的SO2-4分离出来,得到Na2SO4溶液;余下的钙渣再用盐酸溶液溶解其中的Ca2+,除去酸不溶渣,得到CaCl2溶液;将硫酸溶液加到CaCl2溶液中,得到高纯度硫酸钙沉淀和盐酸溶液.盐酸溶液可循环用于溶解钙渣中的Ca2+.硫酸和氢氧化钠溶液则可通过电解Na2SO4溶液制得.最终得到的硫酸钙产品纯度可达99.72%,CaSO4回收率为85.99%.