针对贵阳开磷化肥有限公司生产的湿法磷酸副产品萃余酸中金属阳离子含量较高、黏度大、管道输送困难等问题，对脱除萃余酸中杂质金属离子进行了探索。实验以活性炭为吸附剂、氟硅酸为化学沉淀剂，研究了吸附—化学法脱除萃余酸中杂质金属离子的最佳条件。实验结果表明：反应温度为45℃，过滤萃余酸清液与吸附剂、化学沉淀剂质量比为200：1：5时，过滤清液与活性炭反应10min(t₁)后，继续添加氟硅酸，反应时间t₂=30 min时，萃余酸中杂质金属离子脱除效果最佳，此时萃余酸MER值（磷酸中倍半氧化物的含量与五氧化二磷含量的比值）从15%～16%降到7%左右，达到生产精细磷酸盐的指标要求。
关键词: 吸附-化学法湿法磷酸 / 萃余酸 / 脱除 / 杂质金属离子 / 精细磷酸盐
Abstract:
In response to the issues of high metal cation content, high viscosity and difficulties in pipeline transport related to the by-product residual acid of wet-process phosphoric acid at Guiyang Kailin Fertiliser Co., Ltd., the paper explores to remove impurity metal ions from the residual acid. Using activated carbon as the adsorbent and fluorosilicic acid as the chemical precipitant, the study investigated the optimal conditions for the adsorption-chemical method to remove impurity metal ions from the residual acid. The experimental results indicate that the optimal removal effect of impurity metal ions from the raffinate acid is achieved when the reaction temperature is at 45℃, the mass ratio of filtered raffinate acid clear liquid to adsorbent to chemical precipitant is 200 : 1 : 5, after the reaction time (t₁) between filtered clear acid and activated carbon reaches 10 min, fluorosilicic acid is added to make the reaction time t₂ reach 30 min. At this point, the MER value of the raffinate acid (the content ratio between sesquioxides and phosphorus pentoxide in phosphoric acid) decreases from 15%～16% to approximately 7%, meeting the specification requirements for the production of high-purity phosphates.
Keywords: wet-process phosphoric acid / raffinate acid / removal / impurity metal ions / high-purity phosphates