低品位氧化锌矿和高铁闪锌矿NH₃-（NH₄）₂SO₄体系浸出的研究

【作者】 凌江华；

【导师】 尹周澜；

【作者基本信息】 中南大学 ， 冶金物理化学， 2011， 硕士

【摘要】 锌以其良好的抗腐蚀性能和合金性能,在工业领域具有广泛的应用。近年来,我国锌冶炼工业发展迅速,国内锌精矿的消耗巨大。但由于锌精矿逐步消耗殆尽,导致锌冶炼原料供应紧张。为维持锌冶金工业的可持续发展,必须开发利用各种锌矿资源。我国西南地区蕴藏有丰富的锌矿资源,其中有很大一部分为高铁硫化矿和低品位氧化矿难以采用传统的锌冶炼工艺经济回收矿石中的有价金属。因此开发新的工艺来合理利用难处理锌矿势在必行。氨浸法具有能耗低、除杂简单、污染少、适应性强等优点,在处理复杂、低品位硫化矿和氧化矿时具有显著的技术优势和经济效益。本文以NH3-(NH4)2SO4氨性体系为浸出剂,通过采用不同的处理工艺,分别对兰坪低品位氧化锌矿和高铁闪锌矿进行了实验研究,考察了不同因素对浸出行为的影响。对低品位氧化锌矿进行了42L规模的实验室扩大试验,并探讨了机械球磨强化高铁闪锌矿氨性氧化浸出的作用机理。低品位氧化锌矿探索试验结果表明：pH值、总氨浓度、液固比是影响锌及杂质浸出的主要因素。在浸出剂总氨浓度为3 mol/L、pH为9.60、液固比为4、反应时间为4h的条件下,通过二段逆流浸出工艺对兰坪低品位氧化锌矿进行处理,锌的浸出率>90%,浸出液pH<9.0,能很好地满足萃取工序的要求。在氧化锌矿实验室扩大试验中,兰坪低品位氧化锌矿的总浸出率大于90%,浸出液中锌离子浓度约为13g/L,pH值为8.90-9.00,达到“氨浸-除杂-萃取-电积”工艺预先设定的技术指标。机械活化能够强化高铁闪锌矿的氧化浸出,活化时间、溶液pH值、氧化剂NaClO的用量、球磨气氛等因素对高铁闪锌矿的浸出都有影响。高铁闪锌矿在机械活化过程中颗粒粒径先降低后升高,晶格尺寸减少,晶格畸变率增加,晶体呈现出非晶态化。结合矿物粒径、晶格尺度和畸变率的变化趋势以及锌浸出率随球磨时间延长而不断增大的实验现象,认为当球磨时间较短时,在机械力的撞击、挤压下,矿物颗粒发生脆性破碎和塑性变形,高铁闪锌矿浸出率的提高是矿物比表面积增大和晶格畸变率增加共同作用的结果；当高铁闪锌矿在机械活化作用下比表面储能达到极限值后,矿物粒径不降反升,晶格缺陷与畸变成为促进矿物溶解浸出的主导因素。更多还原

【Abstract】 Zinc is widely used in industry for its good corrosion resistance property and alloy performance. The domestic consumption of zinc concentrates is tremendous with the rapid development of zinc smelting industry. Therefore, it is necessary to exploit all sorts of zinc resources to keep the sustainable and healthy development of zinc metallurgical industry. Resourceful zinc ores are found in southwest of China, a great part of which are high-iron sphalerite and low-grade zinc oxide ore. As a result, it is difficult to extract valuable metals economically by traditional smelting technology. Therefore, the development of new process to deal with the refractory zinc ore is imperative. Ammonia immersion method has significant technical advantages and economic benefits for its low energy consumption, simple purification, less pollution and strong adaptability.The leaching processes of low grade zinc oxide ore from Lanping and high-iron sphalerite in the system of NH3-(NH4)2SO4 have been studied in this paper. The effect of various factors on the leaching behaviors was investigated.42L-scale expanded experiment of low grade zinc oxide ore has been accomplished in laboratory. And the mechanism of mechanical activation during the ammoniacal oxidation leaching process of high-iron sphalerite was also studied.The leaching experimental results of low-grade zinc oxide ore showed that the main parameters for the leaching of zinc and impurities are pH, total ammonia concentration, and liquid/solid ratio. The optimum leaching conditions were found to be the total ammonia concentration 3 mol/L, pH 9.60, liquid/solid ratio 4, leaching time 4 h. More than 90% of zinc was extracted, and pH of lixivium was less than 9.0 in the two-stage counter-current process, which is satisfied with the requirement for the subsequent solvent extraction process. In the expanded experiment of low grade zinc oxide ore, the total leaching ratio exceeded 90%, the concentration of zinc and pH of lixivium were about 13 g/L and 8.90-9.00 respectively, which is suitable for the predetermined qualification of "ammonia leaching-purification-extraction-electro-winning" technique. The mechanical activation could accelerate the extraction of high-iron sphalerite. The activation time, pH of solution, dosage of NaClO, grinding atmosphere were the main factors to the leaching of high-iron sphalerite. With the increase of activation tine, the particle size of the ore grains decreases first and then increases, the lattice strain ratio rises, and the crystalline turns into amorphous during the process of mechanical activation. Combining the changing tendency of particle size, crystallite size and lattice strain with the experimental phenomena that the zinc leaching ratio increases gradually with the prolongation of activation time, it indicates that brittle crush and plastic deformation occurs with the mechanical grinding. The increase of zinc recovery ratio is attributed to the increase of the specific surface area and lattice disorder. When the stored energy of surface reaches the ultimate state, the particle size doesn’t decrease but increase, and the promotion of mineral dissolution is mainly determined by the lattice distortion.更多还原