绿色环保技术浸出难处理金银矿石的试验与机理研究

【作者】 张艮林；

【导师】 童雄；

【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2003， 硕士

【摘要】 作为一种重要的非氰提金方法，硫代硫酸盐法浸出金银具有速度快、无毒、对杂质不敏感以及浸出指标高等优点，并日益受到人们的重视。但硫代硫酸盐法浸金仍然存在一些不可忽视的问题：①大多数浸出实践中都需加热，且温度区间较窄，在工业生产上难以有效控制。②硫代硫酸盐耗量大，成本高。因此，探讨常温常压下的优化浸金工艺以及如何尽量降低硫代硫酸盐的耗量是硫代硫酸盐法浸金工艺研究的重要内容，也是一个非常有意义的方向。 论文通过条件探索试验发现，在常温常压下，液固比、浸出时间、S₂O₃^2-浓度、SO₄^2-浓度、Cu²⁺浓度、SO₃^2-用量以及添加NH₃·H₂O与否都会影响金的浸出率。最后结合硫代硫酸盐法在技术和经济上的可行性，确定了最佳工艺参考条件：液固比3：1，pH=9.70，浸出时间4～6h，Na₂S₂O₃·5H₂O 65g／l(即0.262M S₂O₃^2-)，（NH₄）₂SO₄ 30g／l(即0.227M SO₄^2-)，Na₂SO₃ 30g／l(即0.238M SO₃^2-)，根据矿石含铜量多少适量添加甚至不加Cu²⁺，在保证总氨浓度不过量的情况下应适量添加NH₃·H₂O。 我们站在一个全新的角度，分别从模拟浸出环境和实际浸金过程两个方面比较全面地探索了硫代硫酸盐的消耗规律，研究了各种工艺参数如pH、搅拌速度、Cu²⁺和氨等对硫代硫酸盐稳定性的影响，也研究了添加不同药剂和几种金属离子对硫代硫酸盐的影响，最后探讨了浸出、置换和静置过程中硫代硫酸盐的消耗规律。 在前人研究的基础上，结合自己对试验现象和试验过程的掌握，论文进一步明确了硫代硫酸盐浸金的机理，对一些模糊的认识给出了相对明确的解释和分析，而且我们首次进行了硫代硫酸盐浸金过程的热力学判据的推导，认为只要所用氧化剂的氧化电位φ₁＞-0.128V，硫代硫酸盐浸金反应在热力学上就能够发生；同时也提出了硫代硫酸盐浸金的平衡常数判据：lgK₂₉₈^θ=16.935n（φ₁+0.128）。这些工作为今后硫代硫酸盐法浸金工艺和机理的进一步研究提供了非常有价值的参考。更多还原

【Abstract】 As an important method of gold extraction by free-cyanide reagents, the thiosulfate process has many virtues: being not poisonous, inaction to impurities, high speed and the better leaching rate, so the thiosulfate process is paid more and more attentions. But there are also several un-ignorable problems: ?it must be heated in most situations, and the temperature range is also very small, so it is not controlled validly. ?the consumption and the cost of the thiosulfate is very high. So, it’ s very important for thiosulfate leaching to optimize the technology at normal temperature and pressure and to decrease the thiosulfate consumption.The experiment shows that, at normal temperature and pressure, the ratio of liquid to solid, stirring speed, leaching time, pH, the concentration of S2O32-, SO42-, Cu2+ and SO32-, the adding quantity of NH3 H2O are the main factors affecting the gold leaching rate, Then the optimum operating conditions are obtained according to the feasibility of gold leaching with thiosulfate process in technological and economic performance: the ratio of liquid to solid is 3:1; pH=9.70; the leaching time is 4~6h; the concentrations of Na2S203 5H2O, (NH4)2SO4 and Na2SO3, are 65g/l (0. 262M S2O32-), 30g/l (0. 227M SO42-) and 30 g/1 (0. 238M SO32-) respectively; cupric ions are only needed for the materials without copper; when the total consumption of ammonia is not excessive, NH3 H2O can be added appropriately.From a new angle, the regularities of thiosulfate consumption are studied completely in simulative and actual situation respectively. Effects of pH, stirring speed, Cu2+ and ammonia on the stability of thiosulfate are investigated in order to find out the regularities of thiosulfate consumption. Then effects of adding different regents and metalion on the stability of thiosulfate are also studied. Consequently, the loss of thiosulfate during leaching, cementation laying up processes has been examined experimentally. The loss of thiosulfate is very low under well-controlled conditions.The paper discusses further the mechanism of leaching gold by thiosulfate, also gives relatively clear explains and analyses to some obscure recognitions. In the thesis, author has deduced the thermodynamic criterion of the gold thiosulfate leaching at first, and we have suggested that an oxidant will improve gold leaching proceed as long as the electric potential of an oxidant is over -0. 128V in the light of thermodynamics. The criterion of the equilibrium: lgK 298 =16.935n( +0.128) is also given. These studies of the technology and mechanism about leaching gold by thiosulfate present a valuable reference for the further research.更多还原