柠檬酸对高硫尾砂氧化过程的抑制作用及其机理研究

Study on the Inhibitory Effect and Mechanism of Citric Acid on the Oxidation Process of High Sulfur Tailings

硫化矿石选矿后会产生含硫矿物的尾砂,人们常把硫含量超过8%的尾砂称作高硫尾砂,由于高硫尾砂中硫化物的氧化产生硫酸盐会导致充填体强度下降,因此不宜作为充填材料。有研究认为柠檬酸引起的缓凝反应,可提高高硫尾砂胶结充填体强度。本文通过氧化试验,测试滤液中的硫酸根离子浓度来评估硫化物氧化反应的程度。实验结果显示,柠檬酸的加入显著抑制了高硫尾砂中硫化物的氧化过程。分析得出柠檬酸对高硫尾砂具有抑制作用的原因可能是以下三个方面:(1)柠檬酸溶于水后会发生解离反应,生成的H^(+)抑制了氧化反应;(2)柠檬酸具有较强的还原性,可以产生额外的抗氧化自由基,从而抑制了高硫尾砂中硫化物氧化;(3)未参与还原反应的柠檬酸可以与高硫尾砂中的Fe(Ⅱ)发生络合反应,形成较为稳定的络合物。

After the beneficiation of sulfide ores,tailings containing sulfur-containing minerals will be produced.Tailings with sulfur content exceeding 8%are often referred to as high sulfur tailings.Due to the oxidation of sulfides in high sulfur tailings to produce sulfates,the strength of the filling material will decrease,so they are not suitable as filling materials.Some studies suggest that the retarding reaction caused by citric acid can improve the strength of high sulfur tailings cemented filling materials.This article evaluates the degree of sulfide oxidation reaction by testing the concentration of sulfate ions in the filtrate through oxidation experiments.The experimental results showed that the addition of citric acid significantly inhibited the oxidation process of sulfides in high sulfur tailings.The reason why citric acid has an inhibitory effect on high sulfur tailings may be due to the following three aspects:(1)Citric acid will undergo dissociation reaction after dissolving in water,and the generated H^(+)inhibits the oxidation reaction;(2)Citric acid has strong reducibility and can generate additional antioxidant free radicals,thereby inhibiting the oxidation of sulfides in high sulfur tailings;(3)Citric acid that did not participate in the reduction reaction can undergo complexation reaction with Fe(Ⅱ)in high sulfur tailings,forming a relatively stable complex.