硝酸分解磷矿过程中碘的迁移分布规律

Migration and distribution of iodine in process of decomposing phosphate ore by nitric acid

硝酸分解磷矿是硝酸磷肥生产过程中重要的操作单元。研究了酸解时间为30~240 min、酸解温度为40~90℃、硝酸初始质量分数为40%~65%及酸矿质量比为1.15∶1~1.35∶1对磷矿中碘在气、液、固三相中迁移分布的影响。结果表明:硝酸分解磷矿过程中,碘以单质的形式迁移至气相中。随着酸解时间、酸解温度、硝酸初始浓度的增加,碘在气相中的分布率增大。然而,随着酸矿质量比的增加,气相中的碘呈现出先增加后减小的趋势。酸解时间和酸解温度对碘在气相中分布率的影响最大。当工艺参数控制在酸解温度为60℃、硝酸初始质量分数为55%、酸矿质量比为1.25∶1、酸解时间为120 min时,碘在气、液、固三相中分布率分别为65.21%、26.89%、7.91%。

Phosphate ore decomposed by nitric acid is an important operating unit in the process of nitrophosphate production.The effects of acid hydrolysis time of 30~240 min,temperature of 40~90℃,nitric acid initial mass fraction of 40%~65%and acid to phosphate ore mass ratio of 1.15∶1~1.35∶1 on the migration and distribution of iodine in phosphate ore for gas,liquid and solid phases were studied.The results showed that in the decomposition process of phosphate ore by nitric acid,iodine transferred to the gas phase in the form of elemental.The distribution rate of iodine in gas phase increased with the increase of acidolysis time,temperature and nitric acid initial concentration.However,with the increase of mass ratio of acid to phosphate ore,iodine in the gas phase first increased and then decreased.The distribution rate of iodine in gas phase was more affected by acid hydrolysis time and temperature than by other parameters.When the process parameters were controlled at the acidolysis temperature of 60℃,nitric acid initial mass fraction of 55%,acid to phosphate ore mass ratio of 1.25∶1 and acidolysis time of 120 min,the distribution rate of iodine in the gas phase was 65.21%,the distribution rate in the liquid phase was26.89%,and the distribution rate in the solid phase was 7.91%.