硫酸铵法硝酸磷肥生产高品质硫酸钙工艺研究

研究了昆阳磷矿的硝酸酸解液与硫酸铵反应制备硫酸钙的工艺条件，分别研究了硫酸铵用量、硫酸铵质量分数、温度、加料时间、反应时间对晶体大小和共晶磷含量的影响。确定了结晶过程适宜的工艺条件：硫酸铵用量为理论用量的110%、硫酸铵质量分数为30%、反应温度为90 ℃、加料时间为20 min、反应时间为2 h。在此工艺条件下得到磷质量分数为0.179%、氟质量分数为0.06%的半水和二水混合晶型的硫酸钙结晶，该硫酸钙具有晶体粗大整齐、过滤强度高的优点。

Study on producing process of high-quality calcium sulfate from nitric phosphate by ammonium sulfate method

The process conditions of the reaction between nitric acid acidolysis solution of Kunyang phosphorite and ammonium sulfate to produce calcium sulfate were studied.Effects of the amount of（NH₄）₂SO₄，mass fraction of（NH₄）₂SO₄，reaction temperature，feeding time，and reaction time on the size of crystal and the co-crystallized phosphorus content were investigated.The optimal process parameters of the reaction were obtained as follows: the amount of （NH₄）₂SO₄ was 110%，mass frac- tion of（NH₄）₂SO₄ was 30%，reaction temperature was 90 ℃，feeding time was 20 min，and reaction time was 2 h.Under those conditions，the crystal contained 0.179%（mass fraction）phosphorus and 0.06%（mass fraction） fluorine，in mixture form of calcium sulfate hemihydrate and calcium sulfate dihydrate was obtained，which had the advantages，such as uniform and bigger crystal shape and high filtration rate.