不同pH值对磷矿废石磷素浸出特性影响的实验研究

采用EPA 1314pH酸碱预滴定实验和pH浸出实验,研究了pH对磷矿废石磷元素浸出特性的影响,以及磷矿废石的酸碱缓冲容量。实验结果表明:磷矿废石的碱缓冲容量小,pH从8.75上升到13.50消耗了0.1mmol/g的NaOH,磷矿废石酸的缓冲容量较大,pH从5.50到1.00,共消耗2.2mmol/g的H2SO4;浸提液的酸碱性是影响磷矿废石中磷元素浸出的重要参数,酸性条件下很大程度上促进了磷元素的浸出,随着H+离子浓度的增加,总磷浓度随之升高。相反在碱性条件下的反应过程中,OH-阻碍磷元素的浸出,消耗正磷酸根离子和羟基磷酸根离子,使其生成沉淀,有一定的固磷作用,为磷元素的固化提供了更多途径。

Effects of Different pH on Phosphorus Leaching Characteristics of Shukongping Phosphate Waste Rock

Impacts of pH on the phosphorus leaching behavior of phosphate waste rock and the buffer capacity in phosphate waste rock samples were studied by using EPA 1314 Pre-test titration test and acid digestion. Results show that the alkaline buffer capacity is larger than acid neutralizing capacity. It takes 0.1 mmol/g NaOH to increase pH from 8.75 to 13.50 while it takes 2.2 mmol/g H₂SO₄ to reduce pH from 5.50 to 1.00. The pH of leaching reagent is an important factor affectingleachability of phosphate waste rock. The phosphorus leaching is greatly promoted under acidic conditions and the total phosphorus concentration increases with increasingH⁺ concentration. On the contrary, OH^- blocks the leaching of phosphorus, consumes orthophosphoric ions and hydroxyl phosphate ions to generate precipitation and provides more applications for the curing of phosphorus.