锌氨浸出液的深度净化及模拟电解液中有机物的脱除研究

【作者】 李建；

【导师】 陈启元；

【作者基本信息】 中南大学 ， 物理化学， 2011， 硕士

【摘要】 随着我国硫化锌矿资源的不断枯竭以及锌矿石品位大幅度地降低,对低品位氧化矿的开发和利用成了人们关心的问题。我国云南兰坪氧化铅锌矿资源丰富,是迄今国内探明储量最大的矿床。但该矿石氧化程度深,碱性脉石含量高,矿石中矿物组成复杂,矿物品种多。采用常规的酸浸工艺难以经济高效地处理,因此采用“氨浸-萃取-电积”工艺处理兰坪低品位氧化锌矿是解决问题的关键。锌的电积过程中无机杂质离子和有机物的存在都会降低电流效率,增大能耗,使电锌变脆,甚至出现烧板现象,不利于得到高品质电锌。因此电解之前锌氨浸出液需要深度净化,锌电解液需要脱除有机物。本文目的是研究杂质离子相对量、锌粉添加量、净化温度、净化时间、锌氨浸出液pH及总氨浓度等因素对净化效果的影响。同时研究有机物浓度对锌电积过程的影响,比较几种吸附树脂对电解液中有机物的吸附性能及重复利用性能,以期找到一种吸附效果好且能重复利用的吸附剂。结果表明：总氨浓度对净化效果基本无影响；杂质离子相对量、锌粉添加量、净化时间、净化温度及锌氨浸出液pH是影响净化效果的主要因素；当浸出液中铜镉摩尔比小于0.2或约为0.5时,有利于浸出液的深度净化除镉和铜,当浸出液中镍镉摩尔比小于0.07或约为0.40时,有利于浸出液的深度净化除镉和镍,而钴离子的存在不利于浸出液的深度净化。当合金锌粉添加量为2g/L,净化时间为1h,净化温度为35℃,锌氨浸出液pH为9.03时,通过锌粉的一段净化,得到了含Cu≤50μg/L, Cd≤300μg/L, Co≤100μg/L, Ni≤100μg/LPb≤40μg/L的净化液,满足锌电积要求。本文还分析了酸性条件和氨性条件下锌粉除钴的差别,发现酸性条件下析氢速度大于钴的析出速度,而氨性条件下析氢速度则明显小于钴的析出速度。在锌的电积过程中,有机物的存在不仅降低了电流效率,而且严重影响了锌的外观形貌。通过与活性炭比较,发现SD300型树脂不仅吸附有机物能力强,而且具有优良的重复利用性能,经过5次重复吸附后吸附率仍在65%左右。更多还原

【Abstract】 With the daily exhaustion of the resources of zinc sulfide ore and sharp decrease of grade of zinc ore, the development and utilization of low-grade zinc oxide ore become imperative. The mineral deposit of Lanping region in Yunnan Province is the largest low-grade zinc oxide ore deposit in China. But the oxidation of the ore is complete, the content of alkality gangue is high, the mineral composition is complex, which has various mineral species. It is hard to treat economically and efficiently if conventional acid leaching process is adopted. Therefore, "ammonia leaching-extraction-electrowinning" process is undoubtedly better than acid leaching process for zinc oxide ore with high-alkality gangue.The presence of inorganic and organic impurities markedly decreace the current efficiency and increase energy consumption, embrittle the cathode zinc, and even plate-burning appears in the electrowinning of zinc hydrometallurgy, which is not beneficial to the production of high grade zinc. Therefore, the zinc ammoniacal leaching solution should be deeply purified and organics in the electrolyte must be removed before the electrowinning. this study was to explore the effects of relative amount of metallic impurities, dosage of zinc dust, purification time, purification temperature, pH and total ammonia concentration of zinc ammoniacal leaching solution on the purification of this zinc ammoniacal leaching solution. meanwhile, the effect of the concentration of organics on the zinc electrowinning was studied and the adsorption property and reusage property were compared among several kinds of absorption resins in the hope of seeking for a sorbent with excellent adsorption property and reusage property.The results indicated that total ammonia concentration of the zinc ammoniacal leaching solution had little effect on the cementation and the relative amount of metallic impurities, dosage of zinc dust, purification time, purification temperature and pH of the zinc ammoniacal leaching solution were the main factors which influenced the cementation. Maintaining copper-cadmium mole ratio of approximate 0.5 or less than 0.2 were beneficial to the cementation of cadmium and copper, and maintaining nickel-cadmium mole ratio of approximate 0.40 or less than 0.07 were also beneficial to the cementation of cadmium and nickel. Nevertheless, the presence of cobalt was bad for the cementation of cadmium and cobalt. All metallic impurities can be brought down to acceptable levels under optimized conditions of zinc dust dosage:2g/L, purification time: lh, purification temperature:35℃, pH of the zinc ammoniacal leaching solution: 9.03.The purified solution obtained by one-stage purification which contained Cu≤50μg/L, Cd≤300μg/L, Co≤100μg/L, Ni≤100μg/L Pb≤40μg/L met the requirements of zinc electrowinning. The difference of cementation of cobalt between acidic and ammoniacal medium was also analysed, and it was found that the difficulty of cobalt removal in acidic medium was owing to the greater velocity of hydrogen evolution; on the contrary, the velocity of hydrogen evolution was less obviously than the reduction rate of cobalt in ammoniacal medium. The presence of organics not only decreaced the current efficiency, but also badly changed the deposit morphology and orientation. Compared with active carbon, SD300 showed excellent adsorption property and reusage property, and the adsorption efficiency was maintained about 65% after adsorbing five times.更多还原