【作者】 刘维；

【导师】 唐谟堂；

【作者基本信息】 中南大学 ， 有色金属冶金， 2010， 博士

【摘要】 我国存在大量高碱性脉石型难处理低品位氧化铜矿资源,汤丹铜矿就是这类资源中规模最大、最具有代表性的难处理矿藏。采用酸性介质很难经济可行地处理该类矿物,为此国内外大量科研工作者针对性开发了氨性体系湿法提取工艺或者选冶结合工艺,但效果还不理想。为了大幅提高这类高碱性脉石氧化铜矿的浸出率,本研究采用Me(Ⅱ)-NH4Cl-NH3-H2O(MACA)浸出体系,对该体系中铜的相关固相化合物的热力学稳定区和其相互转化关系及溶解特性进行了研究,并对该体系中铜矿浸出动力学进行了深入研究,继而提出机械活化与氟化氢铵活化浸出高氧化率、高结合率的汤丹氧化铜矿的有效方法,探讨了其活化机理；采用LIX84-1从该体系浸出液中萃取回收铜,对LIX84-1与Cu(Ⅱ)-NH4Cl.NH3-H2O体系的萃取平衡、氨平衡、硫酸反萃平衡做了深入研究；此外本研究还探索了从Cu-NH3-Ethylenediamine-NH4Cl-H2O溶液中直接电积铜的工艺参数。基于质量平衡与电荷平衡构筑各含铜物种在Cu(Ⅱ)NH4Cl-NH3-H2O中的热力学模型,采用电算指数法对模型求解,确定了各含铜物种的溶解特性、各物种的热力学稳定区域以及相关物种之间的相互转化的热力学条件。验证试验终了固相的XRD图谱、各固相的平衡铜浓度与平衡pH值显示热力学预测是准确的。试样粒径减小、氨水和氯化铵浓度增大、液固比增大以及温度提高都有利于高氧化率、高结合率汤丹铜矿浸出速率和浸出率的提高；浸出过程可用收缩核模型描述,受灰分层扩散过程控制,浸出反应表观活化能为23.28kJ／mol。半经验动力学方程可表示为：通过对浸出前后矿样的工艺矿物学性能研究,发现矿样浸出率难以提高是因为被包裹结合氧化铜难浸出导致的。活化15min和30min可将表观反应活化能由未活化的24.13kJ／mol分别降低到15.40kJ／mol和14.76kJ／mol,浸出反应受扩散过程控制；粒度和X射线衍射分析表明,矿粒浸出性能的提高是比表面积提高与晶格畸变共同作用的结果；机械活化处理后结合氧化铜自由化非常明显,硫化铜在活化过程中也有所降低。在最佳普通磨浸工艺条件下浸出矿样,磨浸浸出率比搅拌浸出高出6.35%,磨浸具有一定的活化效果,但不显著。对结合氧化铜产生包裹作用的氧化铁、氧化铝及氧化硅等脉石成分都在NH3-NH4Cl-NH4HF2H2O体系中有一定溶解度；在最佳条件下氟化氢铵活化浸出渣计铜浸出率达到89.85%,氟化氢铵消耗量为32.7-42.5Kg·(t矿)-,浸出液中铁、铝、硅等的含量明显增高。动力学分析发现,氟化氢铵浓度分别为0mol.L-1、0.1mol.L-1、0.3mol.L-1和0.5mol.L-’时的表观反应活化能分别为24.13kJ／mol、21.44kJ／mol、32.68kJ／mol和33.51 kJ/mol,活化浸出过程受扩散控制。各浸出方案比较发现,采用氟化氢铵活化浸出渣计浸出率达到89.85%,就浸出率而言最具优势；添加次氯酸钙氧化浸出时浸出率比不加时高出3.16%；磨浸工艺浸出率相比常规搅拌浸出具有一定优势,但优势不是非常明显；由于阴离子半径较大,硫酸根和碳酸根在矿石内扩散比较困难,使得硫酸铵和碳酸氢铵与氨水组成的浸出体系的浸出率比氯化铵体系要低。绘制了LIX84-1从Cu(Ⅱ)-NH4Cl.NH3-H2O体系中萃取-洗涤-反萃过程平衡关系曲线,并根据平衡曲线确定浸出液萃取-洗涤-反萃过程的最佳工艺条件,在最佳条件条件下获得了超过97%的铜萃取回收率,反萃后液符合电解铜要求,洗涤液富集氨后可返回浸出循环使用。通过对Cu-NH3-Ethylenediamine-NH4Cl-H2O体系直接电积铜探索研究发现,要从铜浓度低于5g·L’溶液中直接电积获得板状阴极铜,除非电流密度低到50-100A.m-2以下；此外,该体系中电积电流效率很低,一般在80%以下,这都降低了该技术工业化利用的可能性。总之,热力学分析结论为确定该体系中铜浸出剂的成分提供了依据,对高碱性脉石型低品位氧化铜矿的有效利用具有重要意义。动力学与相关工艺研究,查清了高氧化率(>90%)、高结合率(>30%)氧化铜矿的浸出率难以提高的原因,并针对性提出了一些解决方案,为改善工艺指明了努力方向。弱酸性氯化铵溶液洗涤负铜有机相中氨方法的采用,为确保氨性体系萃取提铜创造了先决条件,使得电积过程不再被氨富集所困扰,并且实现了负铜有机相中共萃氨的有效回收。更多还原

【Abstract】 There is a large amount of low grade refractory copper oxide ore, of which the gangue is alkaline, exiting in our country. And Tang Dan copper ore is the most big and the typically one. It is very difficult to treat this kind of resoure with acidic lixiviants. In order to extract the copper from this kind of copper oxide ore, many hydrometallurgical processes or leaching-flotation combined processes with the ammonical solution as lixiviant are developed by the researchers. Though these research, it is became feasible to extract copper from the copper oxide ore of which the copper sulfides content is relatively high or the copper oxides content is relatively high but the bonded copper oxides is relatively low. However, because that the leaching rate is too low and the effect of flotation is also not very good, it is still very difficult to use the copper oxide ore of which the oxided rate is more than 90% and bonded rate is more than 30%. In this research, an attempt was made to solve this problem. The NH4Cl-NH3-H2O was used as the lixiviant in this research. The mechanical activating method and NH4HF2 activating method were proposed to strengthen the leaching process after the leaching thermodynamic and dynamic characteristic of the copper oxide ore in the NH4Cl-NH3-H2O solution is systemicly researched. LIX84-1 was used to extract copper from Cu-NH4Cl-NH3-H2O solution. The balance of extraction, ammonia co-extracting and stripping with H2SO4 was determined. The exploration test of directly electrowinning copper from Cu-NH3-Ethylenediamine-NH4Cl-H2O was also conducted in this research.Thermodynamic models were constructed based on both mass and charge balance. And the models were solved with exponential computation method. The dissolving characteristic, the stable area and condition converting to another phase of each phase were determined. The forecast by thermodynamic model was validated to be reliable by the X-ray diffraction patterns of the final solid, the equilibrium concentration of the copper and the equilibrium pH of each solid phases.It was found that the leaching speed and the final leaching rate of the sample was increasd by decreasing the particle size of the sample, increasing the ammonia and ammonium chloride concentration, rising the leaching temperature and liquid to solid rate. The leaching process could be described with the shrinking core model and diffusion through the’ash layer’ was the controlling step. The activation energy was calculated to be 23.279kJ/mol. A semi-empirical equation as following was also fitted to describle the leaching process:The process minerolagical performance of the samples before and after leaching was investigated. The reason why the leaching rate of the sample was so difficult to be improved could be ascribed to the bad leaching characteristic of the enwrapped bonded copper oxide.The apparent activation energy of the samples activated for 15min and 30min was depressed from the unactivated 24.13kJ/mol to 15.40kJ/mol and 14.76kJ/mol, respectively. The leaching process was controlled by the diffusion step through the’ash layer’. The improving of the leaching effect was the co-contribution of increase of both surface area and imperfection content. The phase analysis of the samples shows the bonded copper oxide was greatly released after the mechanical activating. When leaching the sample under the optimal condition, the leaching rate was 6.35% higher than the agitation leaching test. It is means that the milling-leaching prosess have some activation effort but the effort is very limited.Thermodynamic calculation shown that the gangue components of Fe2O3, Al2O3, SiO2 encompassing the bonded copper oxdies could be dissolved partly in the NH3-NH4Cl-NH4HF2-H2O solution. The copper leaching rate was attained 89.85% and the NH4HF2 consumption was about 32.7-42.5kg per ton ore after leaching the sample under the optimal condition. The concentration of Fe, Al and Si in the leached out solution was evidently increased. When the concention of NH4HF2 in solution is 0 mol·L-1、0.1mol·L-1、0.3mol·L-1 and 0.5mol·L-1, the activation energy of leaching process was analysized to be 24.13kJ/mol、21.44 kJ/mol、32.68 kJ/mol and 33.51 kJ/mol, respectively.When using LIX84-1 to extract copper from the leached-out solution after leaching the ore with the solution containing NH4Cl 3mol/L, NH3 2.5mol/L, the extracting-washing-stipping condition was selected according to the equillibrium curves to be:extracting steps 2, extracting A/O 1:1; washing steps 1, washing A/O 5:1; stripping steps 2, stripping A/O 1:2. The whole extracting effect was more than 97% and the stripping solution could be used to electrowinning copper.The exploration tests of directly eletrowinning copper from Cu-NH3-Ethylenediamine-NH4Cl-H2O solution shown that the electricity efficiency and cell voltage was complicatedly inflounced by each operation parameter. It was very difficult to eletrowinning well plated copper when the concentration of copper was lower than 5g·L-1 unless the electricity density was low to 50～100A·m-2. Most of the electricity efficiency was lower than 80% due to the inflounce of Cu(Ⅰ). All these limit the usage of this technology in the industry.Though all of these theoretical and technological study, the reason why leaching rate of the copper oxide ore of which the oxided rate was more than 90% and bonded rate was more than 30% was so difficult to be improved was checked. Some processes are also proposed to solve that problem, which providing a direction for the future work.更多还原