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铜镍硫化矿表面氧化电化学研究

发布时间:2018-11-12 17:51
【摘要】:镍黄铁矿常与黄铜矿赋存,两者可浮性相近且表面都易氧化造成可浮性下降难以分选富集,而常规高碱抑镍浮选效果较差,在铜镍分离过程中部分镍矿物进入铜精矿中,造成镍精矿中镍铜比下降,镍回收率降低,因此对镍黄铁矿和黄铜矿的表面氧化过程和机制进行相关研究,对提高铜镍资源的利用率意义重大。本文考察了镍黄铁矿和黄铜矿在不同p H介质和捕收剂浓度条件下的表面氧化电化学作用机理,获得以下主要结论:(1)由镍黄铁矿和黄铜矿表面氧化的Eh-p H分析,推测出了硫化矿物表面氧化的发生趋势,结合无捕收剂体系下的循环伏安曲线研究可知,两种硫化矿表面氧化的程度决定了其表面性质和可浮性。适度氧化的氧化产物为疏水性的单质硫,硫化矿表现出良好的无捕收剂可浮性;深度氧化产物则为金属氢氧化物和金属硫酸盐等亲水性物质,硫化矿表面亲水。硫化矿表面易在高碱和高电位条件下发生深度氧化。(2)两种硫化矿无捕收剂体系下的Tafel曲线研究表明,p H值对两种硫化矿在体系中的腐蚀动力学参数均有影响,在相同p H值体系中,黄铜矿的腐蚀电位corrE更负移、腐蚀电流密度corri更大,说明黄铜矿更易发生腐蚀。(3)镍黄铁矿和黄铜矿在黄药捕收剂体系中的静电位和电化学测试表明,硫化矿在丁黄捕收剂中阳极反应为疏水性双黄药的氧化生成,且其氧化速率远远大于硫化矿自身的氧化速率,说明捕收剂的加入,大大增强了硫化矿物表面的氧化进程。浮选体系p H超过硫化矿浮选临界p H时,硫化矿强烈的自身氧化将占主导地位,此时矿物表面将覆盖金属氢氧化物、金属硫酸盐等亲水性氧化产物,阻滞捕收剂双黄药在矿物表面的形成,降低其表面疏水性。反之,在浮选临界p H以内,矿物表面双黄药的生成反应将占主导地位,生成的双黄药在矿物表面形成吸附,使矿物表面疏水。(4)硫化矿物的电化学动力学研究表明,捕收剂在矿物表面阳极氧化生成的疏水性双黄药分子层厚度差异使硫化矿物表面的亲疏水程度不同,进而影响硫化矿的可浮性。
[Abstract]:Nickel pyrite often occurs with chalcopyrite, both of which are similar in floatability and easy to be oxidized on the surface. It is difficult to separate and enrich floatability due to the decrease of floatability, but the effect of conventional high-alkali nickel suppression flotation is poor. During the separation of copper and nickel, some nickel minerals enter the copper concentrate. The ratio of nickel to copper in nickel concentrate decreases and the recovery rate of nickel decreases. Therefore, it is of great significance to study the surface oxidation process and mechanism of nickel pyrite and chalcopyrite in order to improve the utilization ratio of copper and nickel resources. In this paper, the electrochemical mechanism of surface oxidation of nickel pyrite and chalcopyrite in different pH medium and collector concentration is investigated. The main conclusions are as follows: (1) Eh-p H analysis of surface oxidation of nickel pyrite and chalcopyrite; The occurrence trend of surface oxidation of sulphide minerals was inferred and the surface properties and floatability of the two sulphide minerals were determined by the degree of oxidation in combination with the cyclic voltammetry curves in the system without collector. The oxidation product of moderate oxidation is hydrophobic simple sulfur, the sulphide ore shows good floatability without collector, and the deep oxidation product is hydrophilic substance such as metal hydroxide and metal sulfate, and the surface of sulphide ore is hydrophilic. The surface of sulphide ore is easily oxidized deeply under high alkali and high potential conditions. (2) the Tafel curves of the two kinds of sulphide ores without collector system show that the, p H value has influence on the corrosion kinetic parameters of the two sulphide ores in the system. In the same pH system, the corrosion potential (corrE) of chalcopyrite is more negative, and the corrosion current density (corri) is larger. (3) Electrostatic potential and electrochemical measurements of nickel pyrite and chalcopyrite in xanthate collector system showed that the anodic reaction of sulphide ore in butadiene collector resulted in hydrophobic double xanthate oxidation. The oxidation rate of sulphide minerals is much higher than that of sulphide minerals, which indicates that the addition of collector greatly enhances the oxidation process of sulphide minerals. When the flotation system pH exceeds the critical pH of sulphide flotation, the strong autooxidation of sulphide will dominate, and the surface of the mineral will be covered with hydrophilic oxidation products such as metal hydroxide, metal sulfate, etc. The formation of the collector dixanthate on the mineral surface was retarded and its hydrophobicity was reduced. On the contrary, within the flotation critical pH, the formation reaction of dixanthate on mineral surface will dominate, and the formed dixanthate adsorbs on the mineral surface, which makes the mineral surface hydrophobic. (4) the electrochemical kinetic study of sulphide minerals shows that, The hydrophobic dixanthate formed by anodic oxidation of the collector on the mineral surface has different hydrophobic degree, which affects the floatability of sulphide ore due to the difference of the molecular layer thickness of the hydrophobic double xanthate on the surface of the sulphide mineral.
【学位授予单位】:江西理工大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:TD923

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