钒页岩氧压酸浸过程中V与Fe的分离工艺研究

为了确定湖北某钒页岩氧压酸浸条件,以K_2SO_4为添加剂,对在氧压酸浸提V过程中K_2SO_4用量、硫酸的体积浓度、氧分压、浸出温度、浸出时间对V、Fe浸出率的影响进行了研究。结果表明,在K_2SO_4用量为7%、硫酸浓度为15%、浸出时间为5 h、氧分压为2.0 MPa、浸出温度为190℃条件下,V的浸出率为89.90%、Fe的浸出率仅为5.73%,较无K_2SO_4条件下V的浸出率提高,Fe的浸出率大幅降低。XRD、FTIR分析表明,K_2SO_4的介入能强化云母晶体结构的破坏,促进V的释放,提高了V浸出率;K+、SO2-4和Fe3+反应生成斜钾铁矾((KFe(SO4)2)沉淀,降低了Fe的浸出率,这是V与Fe有效分离的主要原因。因此,钒页岩氧压酸浸过程中适量添加K_2SO_4,不仅能提高V浸出率,而且能有效分离V与Fe,减少Fe对后续萃取工艺的不利影响。

Separation Process of Vanadium and Iron during Oxygen Pressure Acid Leaching of Vanadium Shale

In order to explore the conditions of oxygen pressure acid leaching for a vanadium shale in Hubei,with K₂SO₄ as additive,the influence of K₂SO₄ dosage，concentration of sulfuric acid，oxygen partial pressure,leaching temperature，and leaching time on leaching rate of vanadium and iron are investigated respectively during the extraction of Vanadium from black shale by oxygen pressure acid leaching.The results showed that under the conditions of K₂SO₄ dosage 7%，the concentration of H₂SO₄ 15%，leaching temperature 190 ℃ for 5h at 2.0 MPa，the leaching rate of vanadium was 89.90% while the leaching rate of iron was only 5.73%.Obviously,the leaching rate of vanadium is increased,and the leaching rate of iron is greatly reduced compared with the tests without K₂SO₄.XRD phase and FTIR analysis showed that the addition of K₂SO₄ intensified the crystal structure destruction of mica which can promote the release of vanadium and increase its leaching rate.Yavapaiite sediment (KFe(SO₄)₂) formed by the reaction of K₊，SO²⁺₄ and Fe³⁺ reduces the leaching rate of iron,that is the main reason for separating vanadium and iron.Therefore，in the oxygen pressure acid leaching process of vanadium shale，the proper addition of K₂SO₄ can increase the leaching rate of vanadium，and also effectively separate Vanadium and Iron，and reduce the negatively effects of Fe on the subsequent extraction process.