有机硅烷对黄铁矿化学氧化的抑制性能及机理研究

发布时间：2018-02-13 14:41

  本文关键词： 有机硅烷 黄铁矿 表面钝化 酸性矿山废水　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：黄铁矿是最为常见的金属硫化物矿物,广泛存在于各种尾矿、废石堆和有价值的原矿中。在自然环境中,黄铁矿容易发生氧化反应导致酸性矿山废水(AMD)污染,进而威胁人类的健康安全。为了从源头上控制AMD的产生,本论文采用电化学技术和传统的化学浸取法相结合,筛选出合适的有机硅烷钝化剂,并探讨有机硅烷钝化黄铁矿的效果和机理,得到有价值的结果主要有:实验选用的三种有机硅烷钝化剂:氨丙基三甲氧基硅烷(APS)、乙烯基三甲氧基硅烷(VTMS)和巯丙基三甲氧基硅烷(PropS-SH)均能在一定程度上抑制黄铁矿电极的阳极反应。循环伏安(CV)、极化曲线(Tafel)和交流阻抗谱图(EIS)结果表明,经过有机硅烷钝化后的黄铁矿相对于黄铁矿原矿的表面电化学行为明显减弱,腐蚀电流密度减小,表面膜阻抗显著增大。说明所选择的三种有机硅烷均能够在黄铁矿表面进行包膜,从而有效的抑制黄铁矿的电化学行为。在化学浸取实验中,经APS、VTMS和PropS-SH钝化后的黄铁矿的总铁浸出抑制率分别为49.4%、71.4%和89.2%;硫酸根离子的浸出抑制率分别达到45.1%、69.1%和89.6%。电化学和化学浸取的实验结果表明APS、VTMS和PropS-SH钝化剂既能在一定程度上抑制黄铁矿的电化学氧化,还能阻碍或减缓黄铁矿的化学氧化,且都证明了三种有机硅烷对黄铁矿的钝化强度为:PropS-SHVTMSAPS。因此,通过电化学手段和化学浸取实验初步筛选出钝化效果最好的钝化剂为PropS-SH。为进一步确定PropS-SH处理黄铁矿的最佳钝化条件,本文研究包膜过程中不同因素对包膜后黄铁矿钝化效果的影响。结果表明,PropS-SH处理黄铁矿的最佳钝化条件为:硅烷浓度为10%;溶液pH为4.0;硅烷水解时间为4 h;硅烷水解温度为40℃。在最佳的钝化条件下,进行为期4个月的淋滤实验以评价钝化后黄铁矿的长期稳定性。实验结果显示,黄铁矿表面的PropS-SH钝化膜在一定时期内,有很好的抗氧化能力,能够阻隔黄铁矿与环境中的水、氧气及细菌的接触,减缓黄铁矿表面所发生的氧化反应,从而减少酸性废水的产生,有一定的实际应用价值。最后,本文采用粉末接触角法和自然吸水率法对PropS-SH钝化后的黄铁矿进行润湿性实验。结果表明:PropS-SH钝化后黄铁矿的接触角相对于黄铁矿原矿增大89.64°,表明其表面疏水性得到显著提高;自然吸水率实验表明PropS-SH钝化后黄铁矿的自然吸水率已不足0.01%。FT-IR和XPS分析结果显示,PropS-SH在黄铁矿表面钝化的机制是已经水解好的有机硅烷与黄铁矿表面的羟基发生交联反应,在黄铁矿表面形成Fe-O-Si化学键,而溶液中硅烷分子相互发生缩聚反应,生成以Si-O-Si为骨架的网状结构。
[Abstract]:Pyrite is the most common metallic sulphide mineral, widely found in various tailings, waste rock piles and valuable raw ores. In the natural environment, pyrite is prone to oxidize and lead to acid mine wastewater (AMD) pollution. In order to control the production of AMD from the source, this paper combines the electrochemical technology with the traditional chemical leaching method to screen the suitable organosilane passivating agent. The effect and mechanism of organosilane passivating pyrite are also discussed. The results are as follows: the three kinds of organosilane passivating agents used in the experiment, namely, aminopropyltrimethoxysilane, vinyltrimethoxy silane and mercapto trimethoxysilane propS-SH, can inhibit Huang Tie to a certain extent. Anodic reaction of ore electrodes. The results of cyclic voltammetry (CV), polarization curve (Tafel) and impedance spectroscopy (EIS) show that, The surface electrochemical behavior of pyrite passivated by organosilane was obviously weakened and the corrosion current density was decreased. The impedance of the surface film increases significantly. The results show that all of the three organosilanes selected can be coated on the surface of pyrite, which effectively inhibits the electrochemical behavior of pyrite. The total iron leaching inhibition rates of pyrite passivated by PropS-SH and PropS-SH were 49.4% and 89.2%, respectively, and the inhibition rates of sulphate ion leaching were 45.1% and 89.6%, respectively. The results of electrochemical and chemical leaching showed that PropS-SH passivator and APSV TMS could be used for a certain period of time. To inhibit the electrochemical oxidation of pyrite, It can also block or slow down the chemical oxidation of pyrite, and all of them prove that the passivation intensity of three kinds of organosilane to pyrite is 1: PropS-SHV TMSAPS. therefore, By electrochemical means and chemical leaching experiments, the best passivating agent is PropS-SH.The best passivation condition for pyrite treatment by PropS-SH is determined. The effect of different factors on the passivation effect of pyrite after coating was studied in this paper. The results show that the optimal passivation conditions for pyrite treated by PropS-SH are as follows: concentration of silane is 10; pH value of solution is 4.0; hydrolysis time of silane is 4 hours; water of silane is treated with water. The decomposition temperature is 40 鈩，

本文编号：1508398