Fe-S-P体系钙组元诱导活化-硫磷同步浮选分离机理研究

Asynchronous reverse flotation is the conventional method for the dephosphorization and desulfurization. However, the effects of dephosphorization and desulfurization are usually unsatisfactory. The main reason is that, required pH values of the pulp environment are different and activation conditions are restricted each other. In order to separate the sulphur and phosphorus minerals from the iron minerals effectively, an innovative beneficiation method is therefore developed. In the present project, magnetite, pyrite and apatite are served as the raw material, forming the Fe-S-P system. Density functional approach is employed to calculate the factors during oxidation reaction processing of pyrite, such as the oxidation reaction energy, electron transfer, density states, etc. Solution chemistry calculation is also conducted to study the effects of calcium ion, hypochlorite ion and oxygen concentration on the sulphur element transformation during the pyrite oxidation reaction processing. Calcium elements induced activation mechanism of four elements coupled with "Sulfur-oxygen-hypochlorite ion-calcium" in system of pyrite surface is studied through oxidation by increasing the oxygen concentrate and adding high concentrate of calcium hypochlorite. Meanwhile, the induced activation model of calcium elements in pyrite is established. Time of flight secondary ion mass spectroscopy (TOF-SIMS), X-ray photoelectron spectroscopy (XPS) and surface potential detection are employed to characterize surface properties of the induced activation of calcium elements in magnetite, pyrite and apatite, respectively. Meanwhile, the surfaces property differences of pyrite and apatite before and after the induced activation are analyzed. Adsorption capacities of mixed fatty acid sodium and contact angle of mineral surfaces are detected to investigate hydrophobicity differences of the magnetite, pyrite and apatite surfaces before and after the induced activation of calcium elements. Finally, factors affecting the processing of the induced activation of calcium elements are investigated through laboratory flotation test. Based on research results of the present project, the innovative prototype named "the synchronization flotation separation of sulphur and phosphorous in the Fe-S-P system by the induced activation of calcium element" can be formed. Moreover, the theoretical basis for practical applications of this innovative prototype can be obtained.

铁矿异步脱硫脱磷是常规的方法，但二者要求不同的pH值环境，活化条件互相制约，严重影响了脱硫脱磷的效果。本项目以Fe-S-P体系中磁铁矿、黄铁矿和磷灰石为研究对象，通过密度泛函计算分析影响黄铁矿表面硫组元氧化反应的分子轨道因素；通过溶液化学计算，研究Ca2+、ClO-和氧浓度对黄铁矿表面硫组分相转变的影响，通过充氧和高浓度次氯酸钙诱导活化方式，研究黄铁矿表面 “硫-氧-次氯酸根-钙”四元耦合诱导机制，建立黄铁矿表面钙组元诱导活化模型；通过TOF-SIMS、XPS和Zeta-电位检测等手段分析钙组元诱导活化前后矿物表面性质的差异；检测混合脂肪酸钠在矿物表面的吸附量和表面接触角，表征钙组元诱导活化前后矿物表面混合脂肪酸钠吸附层的疏水性差异，通过浮选实验，研究钙组元诱导活化的影响因素，形成高磷硫铁精矿“钙组元诱导活化—硫磷同步浮选分离”的新技术原型，并为该新技术原型的实际应用提供理论依据。

铁精矿提质降杂是实现国内铁矿山可持续发展的必经之路。铁矿异步脱硫脱磷是常规的方法，但二者要求不同的pH值环境，活化条件互相制约，严重影响了脱硫脱磷的效果。本项目以Fe-S-P体系中磁铁矿、黄铁矿和磷灰石为研究对象，开展了“钙组元诱导活化-硫磷同步浮选分离机理研究”。黄铁矿晶体表面多组元吸附的密度泛函计算结果表明：OH-和O2促进Ca2+在黄铁矿表面的吸附，Ca2+、CaCO3和 CaSO4是黄铁矿表面重要的钙活性质点。热力学和溶液化学计算结果表明：次酸酸钙和碳酸钠的协同效应促使黄铁矿表面硫、铁组元转化为硫酸钙、碳酸钙、赤铁矿（hematite）和羟基铁（Fe(OH)2）物种，这为黄铁矿表面钙活性质点的稳点罩盖和磷灰石表面钙活性质点的增加创造了重要条件。矿物表面特性研究结果表明：黄铁矿表面次氯酸钙诱导活化产物（FeOH+、Ca+、CaOH+和 CaSO+离子）的总吸附厚度约为41.72nm。次氯酸钙通过阻止了磷灰石表面的溶解和促进钙离子组分的吸附而增加磷灰石表面钙活性质点的密度。磁铁矿界面重构影响的研究结果表明：磁铁矿-黄铁矿-磷灰石三元溶液体系中Ca组元将优先吸附在黄铁矿和磷灰石表面，其对磁铁矿表面性质的影响较小。当混合脂肪酸捕收剂初始浓度为6×10-4mol/L时，黄铁矿、磷灰石和磁铁矿表面捕收剂的吸附量分别为146.1mg/L、144.4mg/L和5mg/L。不同矿物表面对捕收剂吸附的显著差异是实现黄铁矿、磷灰石与磁铁矿浮选分离的重要原因之一。添加次氯酸钙（200mg/L）可以强化黄铁矿、磷灰石矿物表面与混合脂肪酸钠的交互作用。浮选分离试验研究结果表明：以油酸酰胺与十二烷基苯磺酸钠复配物为捕收剂，淀粉和木质素磺酸钠复配物作抑制剂，在推荐的浮选试验条件下，对原矿含磷1.17%，含硫1.01%的磁铁矿精矿，最终获得精矿铁回收率80.45%，磷硫脱除率分别为71.45%和70.45%的良好指标。因此，在小型实验室中通过次氯酸钙诱导活化—硫磷同步浮选实现了磁铁矿与磷灰石、黄铁矿人工混合矿的分离，形成了高磷硫铁精矿“钙组元诱导活化—硫磷同步浮选分离”的新技术原型。并为该技术原型的实际应用提供理论依据。