【作者】 龙怀中；

【导师】 柴立元；

【作者基本信息】 中南大学 ， 冶金工程， 2013， 博士

【摘要】 传统的铅氧化物制备方法要经历金属铅的冶炼和氧化物制备两个过程,流程长、成本高、环境污染严重。从环保及节约能源出发,开发方铅矿—软锰矿协同浸出直接制备铅、锰氧化物新工艺,以替代从铅金属—氧化铅的传统生产工艺具有很大的意义。本文针对从硫化铅矿物资源(即方铅矿精矿)直接制备PbO技术性问题,进行了如下研究：(1)浸出体系的选择和浸出机理的研究；(2)浸出的铅盐的转型与选择性除杂；(3)化学沉淀法制备细粒PbO粉体。通过“协同浸出—选择性除杂—化学合成”的技术路线达到制备PbO和Mn3O4的目的,主要的研究内容和结论如下：1)研究了氯化铵体系中方铅矿转化过程的浸出行为,Tafel曲线和EIS腐蚀电化学分析结果表明,浸出过程生成的钝化膜主要成分为PbCl2。研究了三氯化铁体系中方铅矿转化为可溶性铅盐的浸出过程,浸出过程中加入NaCl,加快了浸出反应速度。研究确定了FeCl3-NaCl-PbS溶液体系方铅矿与FeCl3反应的腐蚀原电池反应机理,NaCl的加入增大了Cl-离子的浓度,促使络合反应的发生,从而加快PbCl2的溶解,加速方铅矿表面反应的发生。2)在FeCl3-NaCl体系研究金属离子Pb2+在不同反应体系中各种组分间的复杂相互作用,及其存在形态、分布和有效控制机制。取得的主要研究结果如下：(1)氯化介质中方铅矿的溶液化学。对方铅矿固体表面的氯络合-溶解行为进行研究,计算考察颗粒表面固体反应产物(PbCl2)的生成与溶解,研究确定FeCl3-NaCl-PbS溶液体系中PbCl2形成及其与溶液相中Cl-结合发生氯络合反应的络合平衡关系。(2)氯化介质中方铅矿的腐蚀电化学。三氯化铁可将方铅矿氧化为可溶性的PbCl2铅盐,在浸出过程中可加入NaCl,使浸出反应生成的PbCl2进一步变成PbCl42-络离子,增大氯化铅在溶液中的溶解度,加快浸出反应速度。3)方铅矿—软锰矿协同浸出及研究,利用廉价的软锰矿作为氧化剂,与方铅矿同时浸出得到铅的化合物和锰的化合物,既解决了方铅矿的氧化剂的问题又解决了软锰矿还原浸出中还原剂的来源问题,又得到了Mn3O4。对方铅矿和软锰矿中铅和锰的浸出、浸出液的净化、硫酸铅的制备以及Mn3O4的制备进行了试验研究；采用电化学测试、配位计算、X—射线衍射、扫描电镜以及电子能谱等方法探讨其反应机理。方铅矿、软锰矿在盐酸溶液和NaCl溶液中的Tafle极化曲线及EIS图表明：电解质溶液中无NaCl时,方铅矿矿物电极在氧化过程中生成了表面膜层,该膜层阻碍方铅矿氧化反应的继续进行,降低了反应速率；配位体NaCl的加入能使方铅矿表面膜层的“阻力”大大降低,提高方铅矿的反应速率；盐酸浓度的变化,也有相似的现象。4)溶液化学研究结果表明,浸出过程中PbCl2主要以[PbCl4]2-配合物的形式存在于溶液中,pClop=0.04\[Cl-]T=0.92mol/L为PbCl2的转溶点,温度对氯化铅在氯化钠溶液中的溶解度影响明显,可以采用降温和稀释同时进行的方法使得浸出的氯化铅从浸出的溶液中析出,随温度降低,[Pb2+]Tmin点下降,是冷却结晶析出PbCl2晶体的化学原理。5)从方铅矿精矿浸出产物(PbCl2)制备PbSO4,然后采用化学沉淀法生成前驱体—碳酸铅(PbCO3)和碱式碳酸铅(2PbCO3·Pb(OH)2)的混合物,前驱体物质在不同的分解温度下可分别得到稳定的中间产物PbOx、Pb3O4和PbO。控制分解温度制备了超细、高纯的PbO功能粉体,所制得的PbO为黄色斜方晶系,且不含其它杂质峰,粉末颗粒呈片状,平均粒径为5μm。6)对方铅矿—软锰矿两矿浸出后,含锰溶液通过分离和净化。浸出液中铁的脱除方法如下,调节溶液的pH值为3.5-4.0利用溶液中未反应完的软锰矿将二价铁离子氧化为针铁矿以脱除。含锰溶液中铅离子、锌离子的脱除采用硫化法,脱除后溶液中的铅离子、锌离子浓度分别为7.73×10-7和1.28×10-6mol/L。含锰溶液中钙离子的脱除采用加入NH4F的方法,脱除后溶液中的钙离子浓度为0.11×10-5mol/L。进行了氧化制备Mn304工艺的试验研究,讨论了Mn3O4制备过程中的机理,通过X—衍射分析、热重分析及能谱分析也证明所制备样品的主要物相为Mn3O4。更多还原

【Abstract】 The preparation of electrode active material lead-sulfate and mangano-anganic-oxide from galena concentrate and pyrolusite using two-ores method was investigated.There are four main components in this research:the recover of lead and manganese, the purification of leaching solution, the preparation of the lead sulfate and the mangano-manganic oxide, and some discussions on the reaction mechanism by XRD, SEM, XPS, the electrochemistry test and complexing coordinate computation. More details are described as follows.Some factors which have effects on the lead recovery and the leaching reaction rate were explored and optimized. The reaction mechanism was studied by electrochemistry test, the complexing computation and microscopic examination. The results show that the formation of production S0membrane and the insolvent production lead-chloride membrane prevent the reaction between the galena and pyrolusite. Adding sodium-chloride at the very beginning of the reaction and adding hydrochloric acid twice during reaction will remarkably increase the recovery of lead and manganese.The iron in the leaching solution can be removed by the goethite method. The most appropriate pulp pH value was found out by the experiment. The concentration of the iron-ion, the lead-ion, the manganese-ion, the zinc-ion at the different pulp pH values were calculated by thermodynamics method, the computed results are consistent with the experimental conclusion.The influence of diluting the leaching solution with distilled water on the lead separating from the solution was researched. The complexing computation shows that the lead ion dissolves in the solution with different complex compound shapes at different temperatures and concentration of Cl-[Cl-]=1mol/L is the appropriate value of separating the lead chloride from the sodium-chloride solution. The atmospherics pressure vulcanization was used to remove heavy metal ions from the solution. The influence of the factors of vulcanization on the removing rate of the heavy metal ion was studied, and the most appropriate factors of vulcanization were found out. The analysis on the thermodynamics shows that the concentration of sulfur-ion is the key factors affecting the removing rate of the heavy metal ion at certain pulp pH value.The conditions of preparing the lead sulfate were studied. The experimental results show that the reaction time and the pulp pH value are the key factors affecting the purity and the average grain diameter of product. The XRD and SEM analyses on the composition and the appearance of product show that the purity of product is99.83%, the average grain diameter of product is250nm.The mangano-manganic oxide was prepared from the purified manganese chloride solution. The preparing conditions were researched by the single factor method and the orthogonal factor method, the most appropriate factors of preparing the mangano-manganic oxide were found out. The E-pH curves of Mn-O-H2O at60℃was drawn up by the thermo-dynamicsis calculation. In addition, the condition of the mangano-manganic-oxide stable existence was discussed based on the E-pH curves. Both the theoretical calculation and the experimental result show that the pulp pH value is the determining factor preparing the mangano-manganic-oxide pure phase. Also the pulp pH is the key factor increasing the produce rate. The XRD and XPS analyses on the product further show that the production is the pure phase mangano-manganic-oxide.更多还原